As filed with the Securities and Exchange Commission on September 2, 2005

Registration No.             

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form S-2

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

BIOTIME, INC.

(Exact name of Registrant as specified in charter)

Copies of all communications, including all communications sent

to the agent for service, should be sent to:

RICHARD S. SOROKO, ESQ.

Lippenberger, Thompson, Welch, Soroko & Gilbert LLP

201 Tamal Vista Blvd.

Corte Madera, California 94925

Tel. (415) 927-5200

     Approximate date of commencement of proposed sale to the public: As soon as practicable after this Registration Statement becomes effective.

     If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933 check the following box.    x 

     If the registrant elects to deliver its latest annual report to security holders, or a complete and legible facsimile thereof, pursuant to Item 11(a)(1) of this Form, check the following box.    o

     If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

     If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

     If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

     If delivery of the prospectus is expected to be made pursuant to Rule 434, please check the following box.    o

CALCULATION OF REGISTRATION FEE

     The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, or until the Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

PROSPECTUS

BIOTIME, INC.

3,574,290 Units Issuable Upon the Exercise of Subscription Rights

1,787,145 Units Issuable to Fill Excess Over-Subscriptions

5,361,435 Common Shares Issuable Upon Exercise of Warrants

Each Unit Consists of One Common Share and One Warrant

        BioTime, Inc. (“BioTime”) is issuing new securities called “rights.” You will receive one right for each BioTime common share you owned as of the close of business on                     , 2005, the record date.

      A group of private investors (the “Guarantors”) have agreed to purchase units that remain unsold at the conclusion of the rights offer. The purchase obligation of the Guarantors is limited to a maximum of $1,787,145.

      The common shares and warrants are quoted on the OTC Bulletin Board (“OTCBB”) under the symbol BTIM and BTIMW, respectively. The rights will be transferable and we expect that prices for the rights will be quoted on the OTCBB under the symbol BTIMR. The units themselves will not be quoted or traded. Instead, the warrants and common shares issuable upon the exercise of the rights will be immediately tradeable apart from the units.

      These securities involve a high degree of risk and should be purchased only by persons who can afford the loss of their entire investment. See “Risk Factors” on page 6.

       Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is                     , 2005.

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TABLE OF CONTENTS

PROSPECTUS SUMMARY
THE RIGHTS OFFER
USE OF PROCEEDS
DESCRIPTION OF SECURITIES
RESALE OF SHARES AND WARRANTS
LEGAL MATTERS
EXPERTS
ADDITIONAL INFORMATION ABOUT BIOTIME
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE
ADDITIONAL INFORMATION
APPENDIX B
PART II.
SIGNATURES
EXHIBIT INDEX
EXHIBIT 1
EXHIBIT 4.4
EXHIBIT 4.5
EXHIBIT 4.7
EXHIBIT 4.8
EXHIBIT 5.1
EXHIBIT 23.1

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Table of Contents

	•	Costs of conducting additional clinical trials of BioTime products;
	•	Costs associated with seeking regulatory approval of our products;
	•	Continued research and product development; and
	•	General and administrative expenses.

Securities Offered		The rights will entitle you to subscribe for and purchase one “unit” for every five rights you hold. Each “unit” will consist of one new common share and one warrant to purchase an additional common share.
		Each warrant entitles the holder to purchase one common share at a price of $2.00 per share. The number of common shares and the exercise price will be proportionally adjusted in the event of a stock split, stock dividend, combination or similar recapitalization of the common shares. The warrants will expire on October      , 2010 and may not be exercised after that date.
		BioTime may redeem the warrants by paying $.05 per warrant if the closing price of the common shares on a national securities exchange or the Nasdaq Stock Market exceeds 200% of the exercise price of the warrants for any 20 consecutive trading days. BioTime will give the warrant holders 20 days written notice of the redemption, setting the redemption date, and the warrant holders may exercise the warrants prior to the redemption date. The warrants may not be exercised after the last business day prior to the redemption date.
Common Shares Outstanding		17,871,450
Common Shares Offered		3,574,290 through the exercise of the rights
		1,787,145 to fill excess over-subscriptions
		5,361,435 through the exercise of warrants(1)

Warrants Offered		3,574,290 through the exercise of rights
		1,787,145 to fill excess over-subscriptions
		600,000 issuable as a fee to the Guarantors
Subscription Price		The subscription price per unit is $0.50.
Over-Subscription Privilege		Shareholders who fully exercise the rights initially issued to them will be entitled to the additional privilege of subscribing for and purchasing any units not acquired by other holders of rights. See “The Rights Offer — Over-Subscription Privilege.”
Distribution of Rights		The rights will be evidenced by subscription certificates which will be mailed to shareholders other than foreign shareholders whose record addresses are outside the United States. A copy of the subscription certificate can be found in Appendix A of this prospectus.
		If your BioTime shares were held in the name of Cede & Co. as nominee for The Depository Trust Company, or in the name of any other depository or nominee, on the record date, you will also receive rights. You should contact your broker-dealer or other financial institution that holds your common shares in order to exercise, sell, or transfer your rights.
How to Exercise Rights		The rights will be evidenced by subscription certificates, which will be distributed to shareholders. You may exercise your rights by completing the subscription certificate and delivering it, together with payment of the subscription price, to the subscription agent, American Stock Transfer & Trust Company, 6201 15th Avenue, Brooklyn, New York 11219 or at 59 Maiden Lane, New York, New York 10038 if you deliver your certificate and payment by hand. Payment may be made either by check drawn on a United States bank or by wire transfer, as explained under “The Rights Offer — Payment for Units.” Rights must be exercised no later than the expiration date. You may not rescind a purchase after exercising your rights. If your subscription certificate is not available for tender on the expiration date, you may still exercise your rights by following the guaranteed delivery procedures described under “The Rights Offer — Payment for Units.”
Sale of Rights		The rights are transferable until the last business day prior to the expiration date. A business day is a day on which the prices of securities are quoted on the OTCBB. The prices for the rights are expected to be quoted on the OTCBB. Trading of the rights will be conducted through the last business day prior to the expiration date. Any commissions in connection with the sale of rights will be paid by the selling rights holder. BioTime and the subscription agent cannot assure that a market for the rights will develop, or the prices at which rights may be sold if a market does develop.
Foreign Restrictions		Subscription certificates will not be mailed to shareholders whose addresses of record are outside the United States. The rights will be held by the subscription agent for foreign shareholders’ accounts until instructions are received to exercise, sell or transfer the rights. If no instructions are received by 5:00 p.m., New York time on

		, 2005, which is three business days prior to the expiration date, the subscription agent will use its best efforts to sell the rights of foreign shareholders. The net proceeds, if any, from such a sale will be paid to the foreign shareholders on a prorata basis. See “The Rights Offer — Foreign Shareholders.”
Important Dates to Remember		Record Date:                     , 2005
		Expiration Date:                     , 2005
		Last Date of Guaranteed Delivery:                     2005
Amendment, Extension or Termination of the Rights Offer		BioTime may, in its sole discretion: (a) terminate the rights offer prior to delivery of the units for which rights holders have subscribed; (b) extend the expiration date to a later date; (c) change the record date prior to the distribution of the rights to shareholders; or (d) amend or modify the terms of the rights offer.

(1)	This amount is the number of common shares that will be issuable upon the exercise of warrants if the all of the rights are exercised and the rights offer is fully over-subscribed. An additional 600,000 common shares may be issued if the warrants issuable as a fee to the Guarantors are exercised.

RISK FACTORS

      An investment in the units involves a high degree of risk. You should purchase the units only if you can afford to lose your entire investment. Before deciding to purchase any of the units offered by this prospectus, you should consider the following factors which could materially adversely affect the proposed operations and prospects of BioTime and the value of an investment in BioTime. There may be other factors that are not mentioned here or of which we are not presently aware that could also affect BioTime’s operations.

      Our ability to generate operating revenue depends upon our success in developing and marketing our products. We may not succeed in marketing our products and we may not receive sufficient revenues from product sales to meet our operating expenses or to earn a profit. In this regard, sales of Hextend to date have not been sufficient to generate an amount of royalties or licensing fees sufficient to cover our operating expenses. Factors that affect the marketing of our products include the following:

      Our net losses for the fiscal years ended December 31, 2002, 2003, and 2004 were $2,844,900, $1,742,100, and $3,085,300, respectively, and we incurred a loss of $1,169,324 for the six months ended June 30, 2005. We have incurred a net loss of $39,637,000 since the inception of our company in 1990. Our ability to generate sufficient operating revenue to earn a profit depends upon our success in developing and marketing or licensing our products and technology for medical use.

      We plan to continue to incur substantial research, product development, and regulatory expenses, and we will need to raise additional capital to pay operating expenses until we are able to generate sufficient revenues from product sales, royalties, and license fees. We have not received an amount of royalties and licensing fees from the sale of Hextend sufficient to cover our operating expenses. As of June 30, 2005, we had $588,540 of cash and cash equivalents on hand. At our current rate of spending, our cash on hand, reimbursable product development fees receivable from Summit, and anticipated royalties from Hospira, will allow us to operate through March 2006. The amount and pace of research and development work that we can do or sponsor, and our ability to commence and complete clinical trials required to obtain FDA and foreign regulatory approval of our products, depends upon the amount of money we have. We plan to spend at least $1,000,000 on clinical trials of PentaLyte. The costs of clinical trials and future research work are not presently determinable due to many factors, including the inherent uncertainty of those costs and the uncertainty as to the timing, source, and amount of capital that will become available for those projects. We have already curtailed the pace of our product development efforts due to the limited amount of funds available, and we may have to postpone further laboratory and clinical studies, unless our cash resources increase through a growth in revenues or additional equity investment or borrowing. Although we will continue to seek licensing fees from pharmaceutical companies for licenses to manufacture and market our products abroad, it is likely that additional sales of equity or debt securities will be required to meet our short-term capital needs. Sales of additional equity securities could result in the dilution of the interests of present shareholders. We may not be able to raise a sufficient amount of additional funds to permit us to develop and market our products. Unless we are able to generate sufficient revenue or raise additional funds when needed, it is likely that we will be unable to continue our planned activities, even if we are making progress with our research and development projects.

      We presently do not have adequate facilities or resources to manufacture our products and the ingredients used in our products. We plan to enter into arrangements with pharmaceutical companies for the production and marketing of our products. Hospira has an exclusive license to manufacture and market Hextend in the United States and Canada, and CJ has an exclusive license to manufacture and market Hextend and PentaLyte in Korea. Hospira’s obligation to pay royalties on sales of Hextend will expire in the United States or Canada when all patents protecting Hextend in the applicable country expire and any third party obtains certain regulatory approvals to market a generic equivalent product in that country. Our current patents will begin to expire in 2019. CJ’s obligation to pay royalties on sales of Hextend and PentaLyte, respectively, will expire when the patents protecting those products in South Korea expire. Although a number of other pharmaceutical companies have expressed their interest in obtaining licenses to manufacture and market our products in other countries, we might not be successful in negotiating other licensing arrangements. If licensing or manufacturing arrangements cannot be made on acceptable terms, we will have to construct or acquire our own manufacturing facilities and establish our own marketing organization, which would entail significant expenditures of time and money.

      During 2003, we lost our Chairman and Chief Executive Officer, Paul Segall, who passed away in June. Following the passing of Dr. Segall, we formed the Office of the President, a three-person executive “office” comprised of the three remaining founders: Dr. Hal Sternberg, Dr. Harold Waitz, and Judith Segall. The Office of the President is charged with assuming those executive duties previously attended to by Dr. Segall. We believe that the Office of the President has provided a smooth management transition without entailing additional operating costs. So long as the Office of the President meets our needs, we will defer appointing a new chief executive officer until our cash flow improves and we have sufficient capital to finance the additional executive compensation expenses. It is not possible to determine what impact, if any, this will have on our operations. Scientific concerns, such as product development and laboratory research, will continue to be addressed primarily by Dr. Sternberg, the Vice-President of Research, who worked very closely with Dr. Segall for many years on all matters of scientific importance and strategy.

      The loss of the services of any of our other executive officers could have a material adverse effect on us. We do not presently have long-term employment agreements with any of our executive officers because our present financial situation precludes us from making long-term compensation commitments in amounts commensurate with prevailing salaries of executive officers of similar companies in the San Francisco Bay Area. This may also limit our ability to engage a new Chief Executive Officer.

Risks Related to Our Industry

      We will face certain risks arising from regulatory, legal, and economic factors that affect our business and the business of other pharmaceutical development companies. Because we are a small company with limited revenues and limited capital resources, we may be less able to bear the financial impact of these risks than larger companies that have substantial income and available capital.

      The products that we develop cannot be sold until the FDA and corresponding foreign regulatory authorities approve the products for medical use. Hextend has been approved for use in the United States, Canada and Korea only. We are conducting a Phase II clinical trial of PentaLyte to demonstrate that PentaLyte can be used safely and effectively as a plasma volume expander in surgery.

      The need to obtain regulatory approval to market a new product means that:

      We have patents in the United States, Canada, several countries of the European Union, Australia, Israel, Russia, South Africa, South Korea, Japan, China, Hong Kong, Taiwan and Singapore, and have filed patent applications in other foreign countries for certain products, including Hextend, HetaCool, and PentaLyte. We might not be able to obtain any additional patents, and any patents that we do obtain might not be comprehensive enough to provide us with meaningful patent protection. Also, there will always be a risk that our competitors might be able to successfully challenge the validity or enforceability of any patent issued to us. The costs required to uphold the validity and prevent infringement of any patent issued to us could be substantial, and we might not have the resources available to defend our patent rights.

      Success in selling our products may depend in part on the extent to which health insurance companies, HMOs, and government health administration authorities such as Medicare and Medicaid will pay for the cost of the products and related treatment. Presently, most health insurance plans and HMOs will pay for Hextend when it is used in a surgical procedure that is covered by the plan. However, until we actually introduce a new product into the medical market place we will not know with certainty whether adequate health insurance, HMO, and government coverage will be available to permit the product to be sold at a price high enough for us to generate a profit. In some foreign countries, pricing or profitability of health care products is subject to government control which may result in low prices for our products. In the United States, there have been a number of federal and state proposals to implement similar government controls, and new proposals are likely to be made in the future.

Risks Pertaining to Our Common Shares

      Before purchasing BioTime common shares or warrants, investors should consider the price volatility of our shares and warrants and the fact that we do not pay dividends.

      The market price of BioTime shares and warrants, like that of the shares of many biotechnology companies, has been highly volatile. The price of BioTime shares and warrants may rise rapidly in response to certain events, such as the commencement of clinical trials of an experimental new drug, even though the outcome of those trials and the likelihood of ultimate FDA approval remain uncertain. Similarly, prices of BioTime shares and warrants may fall rapidly in response to certain events such as unfavorable results of clinical trials or a delay or failure to obtain FDA approval. The failure of our earnings to meet analysts’ expectations could result in a significant rapid decline in the market price of our common shares and warrants. In addition, the stock market has experienced and continues to experience extreme price and volume fluctuations which have affected the market price of the equity securities of many biotechnology companies and which have often been unrelated to the operating performance of these companies. Broad market fluctuations, as well as general economic and political conditions, may adversely affect the market price of the common shares and warrants.

      The common shares and warrants are subject to the so-called penny stock rules that impose restrictive sales practice requirements on broker-dealers who sell penny stocks to persons other than established customers and accredited investors. An accredited investor generally is a person who has a net worth in excess of $1,000,000 or individual annual income exceeding $200,000, or joint annual income with a spouse exceeding $300,000. For transactions covered by this rule, the broker-dealer must make a special suitability determination for the purchaser and must have received the purchaser’s written consent to the transaction prior to sale.

This means that delisting could affect the ability of shareholders to sell their common shares and warrants in the secondary market.

      The Securities and Exchange Commission (the “Commission”) has adopted regulations that define a penny stock to be any equity security that has a market price of less than $5.00 per share or an exercise price of less than $5.00 per share, subject to certain exceptions. If a transaction involving a penny stock is not exempt from the Commission’s rule, a broker-dealer must deliver a disclosure schedule relating to the penny stock market to the investor prior to a transaction. The broker-dealer also must disclose the commissions payable to both the broker-dealer and the registered representative, current quotations for the penny stock, and, if the broker-dealer is the sole market-maker, the broker-dealer must disclose this fact and the broker-dealer’s presumed control over the market. Finally, monthly statements must be sent disclosing recent price information for the penny stock held in the customer’s account and information on the limited market in penny stocks.

      We do not pay cash dividends on our common shares. For the foreseeable future we anticipate that any earnings generated in our business will be used to finance the growth of BioTime and will not be paid out as dividends to our shareholders. This means that our stock may not be a suitable investment for anyone who needs to earn income from their investments.

      A registration statement under the Securities Act of 1933, as amended, must be in effect in order for warrant holders to exercise their warrants. This means that we will have to periodically update our registration statement and prospectus by filing post-effective amendments and by filing our annual report on Form 10-K, our quarterly reports on Form 10-Q, and current reports on Form 8-K as required under the Securities Exchange Act of 1934, as amended. We intend to use our best efforts to keep our registration statement effective. However, if we are unable to do so for any reason, warrant holders would not be able to exercise their warrants, even if the market price of our common shares was then greater than the exercise price. Most states will also require us to obtain a permit, issued through an application for registration or qualification, and to maintain that permit in effect in order for warrant holders in the state to exercise their warrants.

THE RIGHTS OFFER

Issuance of Rights

      We are issuing rights to subscribe for units consisting of common shares and warrants. The rights will be issued to shareholders who owned BioTime shares as of the close of business on                     , 2005, which has been set as the record date. Beneficial owners of shares held in the name of Cede & Co. as nominee for The Depository Trust Company, or in the name of any other depository or nominee, on the record date will also receive rights. Each shareholder will be issued one transferable right for each common share owned on the record date. No fractional rights will be issued. The rights entitle the holders to acquire one common share and one warrant for each five rights held by paying the subscription price. Any shareholder who is issued fewer than five rights may subscribe for one unit at the subscription price. The rights will be evidenced by subscription certificates (see Appendix A) which will be mailed to shareholders other than foreign shareholders whose record addresses are outside the United States. The United States includes the fifty states, the District of Columbia, U.S. territories and possessions.

      The rights issued to foreign shareholders will be held by the subscription agent for their accounts until instructions are received to exercise (if permissible under applicable foreign or state securities laws), sell, or transfer those rights. If no instructions have been received by 12:00 noon, New York City time, three business days prior to the expiration date, the subscription agent will use its best efforts to sell the rights of those foreign

shareholders in the over-the counter market. The net proceeds from the sale of those rights will be paid to the foreign shareholders. See “Sale of Rights.”

      Any common shares acquired by officers, directors and other persons who are “affiliates” of BioTime, as that term is defined under the Securities Act of 1933, may only be sold in accordance with Rule 144 under the Securities Act or pursuant to an effective registration statement under the Securities Act. In general, under Rule 144, as currently in effect, an “affiliate” of BioTime is entitled to sell, within any three-month period, a number of shares that does not exceed the greater of 1% of the then-outstanding common shares or the average weekly reported trading volume of the common shares during the four calendar weeks preceding such sale. Sales under Rule 144 are also subject to certain restrictions on the manner of sale, to notice requirements and to the availability of current public information about BioTime.

Purpose of the Rights Offer

      The Board of Directors of BioTime has determined that it is necessary for BioTime to raise additional capital at this time to finance its operations, including:

      Until we begin to receive sufficient revenues from product sales and licensing fees from Hospira and CJ or other companies that may obtain a license to sell our products, we will have to finance our operations with our cash on hand, the funds received from shareholders who exercise their rights, and any additional capital raised through other sales of equity securities.

      The rights offer provides an opportunity for us to raise additional capital without diluting the ownership interests of existing shareholders who exercise their rights. Shareholders who exercise their rights will be able to purchase BioTime shares at a price below market, without incurring broker’s commissions. Generally, shareholders who exercise their rights in full will be able to maintain their prorata share of BioTime’s outstanding common shares. However, shareholders will experience some dilution to their percentage interests in BioTime by virtue of the warrants issuable to the Guarantors. In this regard, we will issue 600,000 warrants to the Guarantors as compensation under the Standby Purchase Agreement. Also, if the rights offer is oversubscribed and BioTime issues additional common shares and warrants to fill over-subscriptions, shareholders who do not purchase their prorata portion of those additional shares and warrants through the over-subscription privilege would experience a reduction in their percentage interests in BioTime’s outstanding shares. Similarly, shareholders who do not exercise their warrants in full could experience a reduction of their percentage interests in BioTime’s outstanding shares if other warrant holders exercise their warrants. The distribution of the rights to shareholders will also afford those shareholders who choose not to exercise their rights the potential of receiving a cash payment upon the sale of their rights. Therefore, the receipt of rights by shareholders who choose not to exercise their rights may be viewed as compensation for the possible dilution of their interest in BioTime.

      We considered other financing alternatives, including a private placement or underwritten public offering of newly issued shares. Those alternatives would have entailed the payment of commissions and fees to broker-dealers in an amount greater than the $132,000 of cash fees we will pay the Guarantors. A private placement or underwritten public offering would also have been more dilutive to BioTime shareholders because all of the shares could have been sold to new investors. In the case of a private placement, the sale would probably have been made at a discount to market. In contrast, the sale of shares through the rights and warrants will permit BioTime to incur lower transaction fees in raising capital and will permit the shareholders who exercise their rights and warrants to enjoy the price discount that might otherwise have been realized by new investors. During December 2003 and January 2004, January and February 1997, and February and March 1999,

BioTime conducted similar subscription rights offers that were over-subscribed, leading BioTime to conclude that the rights offer might be a better alternative to the other sources of financing.

      In determining the subscription price of the rights we considered the financial condition of BioTime, the price range at which BioTime common shares have traded during recent weeks, the volatility of the price of the common shares, the discounts to the market price and additional broker-dealer or underwriting costs that we would likely have to incur if we were to sell shares in a private placement or an underwritten public offering, and the discounts we allowed in our two previous rights offers. We determined that the subscription price is fair to us and to our shareholders in that it allows our shareholders to realize the economic benefits that might otherwise have been offered to new investors and broker-dealers, while providing us with approximately the same amount of net capital that we would have received through alternative financing arrangements.

      The factors that we considered in determining the subscription price of the rights were also considered in determining the exercise price of the warrants. The warrants are intended to serve as a future source of new capital that we can receive without additional broker-dealer, underwriting, and other transactional costs. We adjusted the price to a premium over the current and recent market price of the common shares to reduce the dilution that will result when the warrants are exercised. Dilution will result from the exercise of the warrants because warrant holders will not exercise the warrants unless the market price of our common shares is greater than the exercise price of the warrants. To further limit future dilution, we made the warrants redeemable when the market price of the common shares exceeds 200% of the exercise price for 20 consecutive trading days. We also felt that the warrants will provide an extra incentive for our shareholders to exercise their rights and to continue to participate as equity holders in our company. The exercise price of the new warrants is the same as the exercise price of the warrants we issued through our last subscription rights offer.

The Subscription Price

      The subscription price for the units to be issued pursuant to the rights offer is $0.50. We announced the rights offer on                     , 2005. The high and low bid price of the common shares on the OTCBB on                     , 2005 and                     , 2005 was $          and $          , respectively.

Expiration of the Rights Offer

      The rights offer will expire at 5:00 p.m., New York City time, on                     , 2005, the expiration date. Rights will expire on the expiration date and may not be exercised after that date.

Exercise of Rights

      In order to exercise your rights you must do all of the following:

      You should send your signed subscription certificates, accompanied by payment of the subscription price, to American Stock Transfer & Trust Company, the subscription agent, by one of the methods described below:

      (1) By hand:

      (2) By mail, express mail or overnight courier:

      (3) By facsimile (telecopier):

      You should confirm that your facsimile has been received by contacting the subscription agent by telephone at 1-877-248-6417, or outside the United States, (718) 921-8317 and ask for Shareholder Relations. If you deliver your subscription certificate by telecopier, you must send the original subscription certificate to the subscription agent by mail or hand delivery.

Do not send subscription certificates to BioTime.

      If your BioTime shares were held in the name of Cede & Co. as nominee for The Depository Trust Company, or in the name of any other depository or nominee, on the record date, you should contact your broker-dealer or other financial institution that holds your common shares in order to exercise, sell, or transfer your rights.

      A subscription will be deemed accepted by the subscription agent when payment, together with a properly completed and executed subscription certificate, is received by the subscription agent at its Reorganization Department.

      If you are issued fewer than five rights, you may subscribe for one full unit. Fractional shares and fractional warrants will not be issued. If after exercising your rights you are left with fewer than five rights, you will not be able to exercise the remaining rights.

      If you do not indicate the number of rights you are exercising, or if you do not deliver full payment of the subscription price for the number of units that you indicate you are subscribing for, then you will be deemed to have exercised rights to purchase the maximum number of units determined by dividing the total subscription price you paid by the subscription price per unit.

      If you submit payment for more units than may be purchased through the regular exercise of your rights, your excess payment will be deemed to be a subscription payment for additional units through the over-subscription privilege. The number of additional units that you will be deemed to have subscribed for in the over-subscription privilege will be determined by dividing the amount of the excess payment by the subscription price per unit.

      All questions concerning the timeliness, validity, form and eligibility of any exercise of rights or subscriptions pursuant to the over-subscription privilege will be determined by BioTime. BioTime’s determination will be final and binding. BioTime in its sole discretion may waive any defect or irregularity, or may permit any defect or irregularity to be corrected, within such time as BioTime may determine. BioTime may reject, in whole or in part, the purported exercise of any right or any subscription pursuant to the over-

subscription privilege. Neither BioTime nor the subscription agent will be under any duty or obligation to give any notification or to permit the cure of any defect or irregularity in connection with the submission of any subscription certificate, the exercise or attempt to exercise any right or the over-subscription privilege, or the payment of the subscription price. Subscriptions through the exercise of rights or the over-subscription privilege will not be deemed to have been received or accepted by BioTime until all irregularities or defects have been waived by BioTime or cured to the satisfaction of, and within the time allotted by, BioTime in its sole discretion.

Over-Subscription Privilege

      The over-subscription privilege may allow shareholders to acquire more units than the number issuable upon the exercise of the rights issued to them. By exercising the over-subscription privilege, shareholders who have exercised all exercisable rights issued to them may purchase any units that are left over by shareholders who fail to exercise their rights.

      The over-subscription privilege may only be exercised by shareholders who were shareholders on the record date and who exercise all of the rights they received from BioTime. Any person who purchases rights and who was not a shareholder on the record date may not exercise the over-subscription privilege. Shareholders such as broker-dealers, banks, and other professional intermediaries who hold shares on behalf of clients may participate in the over-subscription privilege for the client if the client fully exercises all rights attributable to him.

      If you are eligible to exercise the over-subscription privilege and you wish to do so, you should indicate on the subscription certificate how many units you are willing to acquire through the over-subscription privilege. If sufficient units remain unsold, all over-subscriptions will be honored in full.

      If you were a shareholder on the record date and you wish to exercise the over-subscription privilege through The Depository Trust Corporation, you must properly execute and deliver to the subscription agent a DTC Participant Over-Subscription Form, together with payment of the subscription price for the number of units that you wish to purchase through the over-subscription privilege. Copies of the DTC Participant Over-Subscription Form may be obtained from the subscription agent. Your properly executed DTC Participant Over-Subscription Form and payment must be received by the subscription agent at or prior to 5:00 p.m., New York City time on the expiration date.

      If subscriptions for units through the over-subscription privilege exceed the initial 3,574,290 units being offered by BioTime through the exercise of the rights, BioTime may issue up to 1,787,145 additional units to fill all or a portion of the excess over-subscriptions. The issuance of units to fill excess over-subscriptions may dilute the percentage ownership interests of other shareholders.

      BioTime will not be obligated to issue any units to fill excess over-subscriptions, but it may do so in its sole and absolute discretion. BioTime reserves the right to limit the number of units issued to fill an excess over-subscription from any single shareholder or from shareholders that are known or believed by BioTime to be under common control or acting as a group for the purpose of acquiring units.

      Subject to the right of BioTime to limit the number of units issuable to any shareholder, if the rights offer is over-subscribed so that over-subscriptions cannot be filled in full, the available units will be allocated among those who over-subscribe based on the number of rights originally issued to them, so that the number of units issued to shareholders who subscribe through the over-subscription privilege will generally be in proportion to the number of common shares owned by them on the record date. The percentage of remaining units each over-subscribing shareholder may acquire may be rounded up or down to result in delivery of whole units. The allocation process may involve a series of allocations in order to assure that the total number of units available for over-subscriptions is distributed on a prorata basis. If you are not allocated the full amount of units that you subscribe for pursuant to the over-subscription privilege, you will receive a refund of the subscription price you paid for units that are not allocated to and purchased by you. The refund will be made by a check mailed by the subscription agent.

Payment for Units

      If you wish to exercise your rights or to acquire units pursuant to the over-subscription privilege, you may choose between the following methods of payment:

      1. You may send to the subscription agent full payment for all of the units you wish to acquire, including any additional units that you desire to acquire through the over-subscription privilege, if you are entitled to exercise the over-subscription privilege. Make sure that your payment is accompanied by your completed and signed subscription certificate. The payment and properly completed and executed subscription certificate must be received by the subscription agent no later than 5:00 p.m., New York City time, on the expiration date. The subscription agent will deposit all checks received by it for the purchase of units into a segregated interest-bearing account of BioTime pending proration and distribution of units. The interest earned on the account will belong to BioTime.

      To be accepted, your payment must be made in the following manner:

      Wire transfers should be directed to American Stock Transfer & Trust Company, Subscription Agent, JP Morgan Chase Bank WIRE CLEARING ACCOUNT ABA #021000021, Account 323-212069, Attention: Reorg. Dept.

      2. Alternatively, a subscription will be accepted by the subscription agent if, prior to 5:00 p.m., New York City time, on the expiration date, the subscription agent has received (1) payment of the full subscription price in the manner described above for the units subscribed for, including any additional units subscribed for pursuant to the over-subscription privilege, and (2) a notice of guaranteed delivery by facsimile telecopy or otherwise from a bank, a trust company, or a New York Stock Exchange member guaranteeing delivery of a properly completed and executed subscription certificate. The notice of guaranteed delivery and payment in full of the subscription price must be received by the subscription agent before 5:00 p.m., New York City time, on the expiration date. The subscription agent will not honor a notice of guaranteed delivery unless full payment for the units is received by subscription agent by the expiration date and a properly completed and executed subscription certificate is received by the subscription agent by the close of business on the third business day after the expiration date.

      You will not be allowed to rescind your purchase after the subscription agent has received a properly executed subscription certificate or a notice of guaranteed delivery and payment either by means of a wire transfer, check or money order.

      Nominees who hold common shares for the account of others, such as brokers, trustees or depositories for securities, should notify the respective beneficial owners of the common shares as soon as possible to ascertain the beneficial owners’ intentions and to obtain instructions with respect to the rights. If the beneficial owner so instructs, the nominee should complete the subscription certificate and submit it to the subscription agent with the proper payment. In addition, beneficial owners of common shares or rights held through a nominee should contact the nominee and request the nominee to effect transactions in accordance with the beneficial owner’s instructions.

Sale of Rights

      The rights are transferable until the last business day prior to the expiration date. Assuming a market for the rights develops, the rights may be purchased and sold through usual brokerage channels. Although no assurance can be given that a market for the rights will develop, trading in the rights may be conducted until and including the close of trading on the last business day prior to the expiration date.

      You may transfer some or all the rights evidenced by your subscription certificate by following these instructions and the instructions on the back of your subscription certificate. If you wish to transfer all of your rights, you need only sign your subscription certificate and deliver it to the subscription agent. If you wish to transfer some but not all of your rights, you must also deliver to the subscription agent a subscription certificate properly endorsed for transfer with instructions to register the portion of the rights evidenced by the subscription certificate in the name of the transferee and to issue a new subscription certificate to the transferee evidencing the number of rights transferred. In that event, a new subscription certificate evidencing the balance of the rights will be issued to you or, if you so instruct, to an additional transferee.

      If you wish to transfer all or a portion of your rights, you should allow sufficient time prior to the expiration date for (1) the transfer instructions to be received and processed by the subscription agent; (2) a new subscription certificate to be issued and transmitted to the transferee or transferees with respect to transferred rights, and to you with respect to retained rights, if any; and (3) the rights evidenced by the new subscription certificate to be exercised or sold by the recipients. BioTime and the subscription agent shall have no liability to a transferee or transferor of rights if subscription certificates are not received in time for exercise or sale prior to the expiration date.

      BioTime anticipates that the rights will be eligible for transfer through the facilities of The Depository Trust Company.

      Except for the fees charged by the subscription agent, which will be paid by BioTime, all commissions, fees and other expenses, including brokerage commissions and transfer taxes, incurred in connection with the purchase, sale or exercise of rights will be for the account of the transferor of the rights, and none of those commissions, fees or expenses will be paid by BioTime or the subscription agent.

Amendment, Extension or Termination of the Rights Offer

      BioTime reserves the right, in its sole discretion, to: (a) terminate the rights offer prior to delivery of the units for which rights holders have subscribed; (b) extend the expiration date for up to 21 days; (c) change the record date prior to distribution of the rights to shareholders; or (d) amend or modify the terms of the rights offer. If BioTime amends the terms of the rights offer, an amended prospectus will be distributed to each holder of record of rights and to each person who previously exercised any of their rights. An extension of the expiration date for up to 21 days will not be deemed an amendment or modification of the rights offer. If you exercised your rights prior to the amendment or within four business days after the mailing of the amended prospectus, you will be given the opportunity to confirm the exercise of your rights by executing and delivering a consent form.

      If you exercise rights before or within four days after mailing of an amended prospectus relating to an amendment of the rights offer and you fail to deliver, in a proper and timely manner, a properly executed consent form, you will be deemed to have rejected the amended terms of the rights offer and you will be deemed to have elected to revoke in full the exercise of your rights and the over-subscription privilege. If your exercise of rights is so revoked, the full amount of the subscription price you paid will be returned to you.

      If your executed subscription certificate is received by the subscription agent more than four days after the mailing of an amended prospectus, you will be deemed to have accepted the amended terms of the rights offer in connection with the exercise of your rights and the over-subscription privilege.

      If we extend the expiration date for more than 21 days, or we materially amend any other terms of the rights offer, we will file a post-effective amendment to the registration statement with the Securities and Exchange Commission and we will distribute an amendment to the prospectus to holders of record of the

rights specifying the new expiration date. In that case we will promptly return the subscription price you paid, except to the extent that we have already issued your units, and you will be given the opportunity to reconfirm your subscription in the manner described above with respect to amendments of the terms of the rights offer.

      If BioTime elects to terminate the rights offer before delivering the units for which you subscribed, the subscription price you paid will be returned to you promptly by mail. Except for the obligation to return the subscription price you paid when you attempted to exercise your rights, neither BioTime nor the subscription agent will have any obligation or liability to you in the event of an amendment or termination of the rights offer.

Delivery of Share and Warrant Certificates

      Certificates representing the common shares and warrants you purchase by exercising your rights will be delivered to you as soon as practicable after your rights have been validly exercised and full payment for the units has been received and cleared. Certificates representing common shares and warrants you purchase pursuant to the over-subscription privilege will be delivered to you as soon as practicable after the expiration date and after all allocations have been affected. It is expected that the certificates will be available for delivery five business days following the expiration date.

Subscription Agent

      The subscription agent is American Stock Transfer & Trust Company, which will receive for its administrative, processing, invoicing and other services as subscription agent, a fee estimated to be $25,000, and reimbursement for all out-of-pocket expenses related to the rights offer. The subscription agent is also BioTime’s transfer agent and registrar. Questions regarding the subscription certificates should be directed to American Stock Transfer & Trust Company, Reorganization Department, 6201 15^th Avenue, Brooklyn, New York, 11219; telephone (718) 921-8317 or toll free in the United States 877-248-6417. Shareholders may also consult their brokers or nominees.

Federal Income Tax Consequences

      The U.S. Federal income tax consequences to holders of common shares with respect to the rights offer will be as follows:

      1. The distribution of rights will not result in taxable income nor will the holder realize taxable income as a result of the exercise of rights.

      2. The basis of a right will be (a) to a holder of common shares to whom it is issued, and who exercises or sells the right (1) zero, if the market value of the right immediately after issuance is less than 15% of the market value of the common share with regard to which it is issued, unless the holder elects, by filing a statement with his timely filed federal income tax return for the year in which the rights are received, to allocate the basis of the common share between the right and the common share based on their respective market values immediately after the right is issued, and (2) a portion of the basis in the common share based upon the respective values of the common share and the right immediately after the right is issued, if the market value of the right immediately after issuance is 15% or more of the market value of the common share with respect to which it is issued; (b) zero, to a holder of common shares to whom it is issued and who allows the right to expire; and (c) the cost to acquire the right, to anyone who purchases a right in the market.

      3. The holding period of a right received by a holder of a common share includes the holding period of the common share.

      4. Any gain or loss on the sale of a right will be treated as a capital gain or loss if the right is a capital asset in the hands of the seller. A capital gain or loss will be long-term or short-term, depending on how long the right has been held, in accordance with paragraph 3 above. A right issued with regard to a common share will be a capital asset in the hands of the person to whom it is issued if the common share was a capital asset in the hands of that person. If a right is allowed to expire, there will be no loss realized unless the right had been acquired by purchase, in which case there will be a loss equal to the basis of the right.

      5. If a right is exercised by the holder of common shares, the basis of the common share and warrant received will include the basis allocated to the right and the amount paid upon exercise of the right.

      6. If a right is exercised, the holding period of the common share and warrant acquired begins on the date the right is exercised.

      7. Gain recognized by a non-U.S. shareholder on the sale of a right will be taxed in the same manner as gain recognized on the sale of common shares.

      Proceeds from the sale of a right may be subject to withholding of U.S. taxes at the rate of 31% unless the seller’s certified U.S. taxpayer identification number or certificate regarding foreign status is on file with the subscription agent and the seller is not otherwise subject to U.S. backup withholding. The 31% withholding tax is not an additional tax. Any amount withheld may be credited against the seller’s U.S. federal income tax liability.

      The foregoing discussion of the applicable federal income tax law does not include any state or local tax consequences of this transaction. Shareholders and other rights holders should consult their tax advisers concerning the tax consequences of the rights offer.

Special Considerations

      As a result of the terms of the rights offer, shareholders who do not fully exercise their rights should expect that they will, at the completion of the rights offer, own a smaller proportional interest in BioTime than would otherwise be the case.

Standby Guaranty

      The Guarantors have entered into a Standby Purchase Agreement under which they have agreed to purchase any units that remain unsold at the termination of the rights offer, excluding units that have been authorized to be sold to fill excess over-subscriptions. The Guarantors’ obligations are limited to $1,787,145 (3,574,290 units). The obligation to purchase units is pro rata, based on the maximum purchase obligations of each of the Guarantors.

      We have agreed to pay the Guarantors a cash fee in the amount of $132,000, to pay up to $15,000 of the fees and expenses of the Guarantors’ counsel, and to issue to the Guarantors a warrant to purchase 600,000 common shares. The warrants issuable to the Guarantors will be on the same terms as the warrants contained in the units offered to shareholders through the rights. The fees and warrants will be allocated among the Guarantors in the ratio of their respective standby purchase commitments.

      We have registered for sale under the Securities Act of 1933, as amended, the warrants and the common shares issuable upon the exercise of the warrants issued to the Guarantors, and we have agreed to register for resale by them any common shares and warrants they may acquire through their standby purchase commitments. We have agreed to indemnify the Guarantors from certain liabilities, including liabilities arising under the Securities Act.

      The following table shows the maximum amount of the standby purchase commitments of the Guarantors:

Alfred D. Kingsley and Broadwood Partners, LP beneficially owns more than 5% of the outstanding common shares of BioTime. Mr. Kingsley is a general partner of Greenhouse Partners, LP, which is the general partner of Greenway Partners, LP. Cyndel & Co., Inc. and its affiliates could become the beneficial owners of more than 5% of the common shares by acquiring shares and warrants as Guarantors or through the exercise of rights in the rights offer.

USE OF PROCEEDS

      The net cash proceeds received by BioTime from the sale of the 3,574,290 units in the rights offer are estimated to be $          , after deducting the expenses of the offer of approximately $          , without taking into account any common shares that may be sold through the exercise of warrants. An additional $893,573 of cash proceeds may be received through the sale of up to 1,787,145 units to fill excess over-subscriptions. BioTime intends to use the net proceeds of the rights offer as shown in the following table. The minimum amount of proceeds reflects the proceeds from the sale of 3,574,290 units in the rights offer only, and the maximum amount also includes proceeds from the sale of 1,787,145 units to fill excess over-subscriptions.

      Clinical Trials of PentaLyte. Up to $          of the proceeds allocated to research and development will be used to finance clinical testing and FDA application of PentaLyte and the preparation of a New Drug Application to the FDA. We are presently conducting a Phase II clinical trial of PentaLyte to treat hypovolemia in cardiac surgery. We have spent more than $2,400,000 in direct costs, not including certain consultant fees, patent costs, regulatory costs, and overhead expenses, through June 30, 2005 developing PentaLyte. If Hospira obtains a license to manufacture and market PentaLyte under our License Agreement with them, they would reimburse us for our costs incurred in developing PentaLyte. Hospira’s decision whether to license PentaLyte would follow the completion of our Phase II trial.

      Working Capital. We intend to apply the balance of the proceeds of the rights offer to research and development and general corporate purposes. We will have broad discretion with respect to the use of proceeds retained as working capital. The proceeds allocated to research and development may be used to finance additional clinical trials of Hextend, initial clinical trials of HetaCool, and laboratory testing of other products we are developing. When laboratory testing of a product has been completed, a portion of the proceeds allocated to research and development may also be used to commence clinical trials of that product. We may also use a portion of the proceeds to fund the cost of seeking regulatory approval of our products. The proceeds may be used to defray overhead expenses and for future opportunities and contingencies that may arise. We expect that our general and administrative expenses will increase as we achieve progress in developing products and bringing them to market. For example, a portion of the proceeds allocated to working capital may be used to pay the salaries, benefits and fees to employees and consultants who assist in the preparation of applications to the FDA and foreign regulatory agencies and patent applications. Proceeds allocated to working capital also may be reallocated to research and development and may be used to pay the costs of clinical trials of our products.

      New Product Lines and Technologies. We are considering a number of opportunities to enter new fields of research for the development of medical products that may complement our current products or may allow us to enter new market segments. We may use a portion of the proceeds allocated to working capital for the research and development of new product lines and technologies which may include fields of research different from those we have undertaken in the past. We may conduct this research ourselves or in collaboration with others.

      The foregoing represents only an estimate of the allocation of the net proceeds of the rights offer based upon the current state of our product development program. The development of new medical products and

technologies often involves complications, delays and costs that cannot be predicted, and may cause us to make a reallocation of proceeds among the categories shown above or to other uses. We may need to raise additional capital after the rights offer to pay operating expenses until such time as we are able to generate sufficient revenues from product sales, royalties, and license fees.

      Until used, the net proceeds of the rights offer will be invested in certificates of deposit, United States government securities or other high quality, short-term interest-bearing investments.

DESCRIPTION OF SECURITIES

Subscription Rights

      The rights will entitle the holders to subscribe for and purchase for the subscription price one unit for every five rights owned. Each unit will consist of one BioTime common share and one warrant to purchase one common share. The subscription price is $0.50 per unit. Holders of the common shares will receive one right for each BioTime common share owned as of the close of business on the record date. The rights will expire at 5:00 p.m. New York City time on                     , 2005. We may extend the expiration date for up to 21 days. More detailed information about how to exercise the rights can be found in this prospectus under “The Rights Offer — Exercise of Rights” and “The Rights Offer — Payment for Units.”

      Rights holders who exercise all of the rights originally issued to them may also be able to purchase any units that are left over by shareholders who fail to exercise their rights. BioTime may also issue up to 1,787,145 additional units at the subscription price of $0.50 per unit, for a total of $893,573, to fill excess over-subscriptions. Further information on over-subscriptions can be found in this prospectus under “The Rights Offer — Over-Subscription Privilege.”

Units

      Each unit will consist of one new common share and one warrant to purchase an additional common share.

Common Shares

      BioTime’s Articles of Incorporation currently authorize the issuance of up to 40,000,000 common shares, no par value, of which 17,871,450 shares were outstanding at August 15, 2005 and held by 5,509 persons based upon the share position listings for the common shares. Each holder of record is entitled to one vote for each outstanding common share owned by him on every matter properly submitted to the shareholders for their vote.

      Subject to the dividend rights of holders of any of the preferred shares that may be issued from time to time, holders of common shares are entitled to any dividend declared by the Board of Directors out of funds legally available for that purpose. BioTime has not paid any cash dividends on its common shares, and it is unlikely that any cash dividends will be declared or paid on any common shares in the foreseeable future. Instead, BioTime plans to retain our cash for use in financing our future operations and growth.

      Subject to the prior payment of the liquidation preference to holders of any preferred shares that may be issued, holders of common shares are entitled to receive on a prorata basis all remaining assets of BioTime available for distribution to the holders of common shares in the event of the liquidation, dissolution, or winding up of BioTime. Holders of common shares do not have any preemptive rights to become subscribers or purchasers of additional shares of any class of BioTime’s capital stock.

Preferred Shares

      BioTime’s Articles of Incorporation currently authorize the issuance of up to 1,000,000 preferred shares, no par value. We may issue preferred shares in one or more series, at any time, with such rights, preferences, privileges and restrictions as the Board of Directors may determine, all without further action of our

shareholders. Any series of preferred shares which may be authorized by the Board of Directors in the future may be senior to and have greater rights and preferences than the common shares. There are no preferred shares presently outstanding and we have no present plan, arrangement or commitment to issue any preferred shares.

Warrants

      Each warrant entitles the holder to purchase one common share at a price of $2.00 per share. The number of common shares and exercise price will be proportionally adjusted in the event of a stock split, stock dividend, combination or similar recapitalization of the common shares. The warrants will expire on October      , 2010 and may not be exercised after that date.

      Warrants may be exercised in whole or in part by presentation of a warrant certificate to the warrant agent and payment of the exercise price. The purchase form on the reverse side of the warrant must be signed by the warrant holder and the warrant holder’s signature must be guaranteed by a financial institution that is a participant in a recognized signature guarantee program. Payment of the exercise price of the warrants must be made in cash or by certified or bank cashier’s check or wire transfer. If your warrants are held in the name of Cede & Co. as nominee for The Depository Trust Company, or in the name of any other depository or nominee, you should contact your broker-dealer or other financial institution that holds your warrants in order to exercise them.

      BioTime may redeem the warrants by paying $.05 per warrant if the closing price of the common shares on a national securities exchange or the Nasdaq Stock Market exceeds 200% of the exercise price of the warrants for any 20 consecutive trading days ending not more than 20 days before the Company sends a notice of redemption to the warrant holders (the “Trigger Period”). We will give the warrant holders at least 20 days written notice of the redemption, setting the redemption date, and the warrant holders may exercise the warrants prior to the redemption date. The warrants may not be exercised after the last business day prior to the redemption date.

      The redemption date will abate, and the notice of redemption will be of no effect, if the closing price or average bid price of BioTime common share does not equal or exceed 120% of the exercise price of the warrants on the redemption date and each of the five trading days immediately preceding the redemption date. However, BioTime will have the right to redeem the warrants at a future date if the market price of the common shares again exceeds 200% of the exercise price for 20 consecutive trading days, as described above. In addition, BioTime may not redeem the warrants unless a registration statement with respect to the warrants and underlying common shares is effective under the Securities Act during the Trigger Period and during the 20 day period ending on the redemption date.

      In connection with a rights offer completed during January 2004, BioTime issued warrants having the same terms as the warrants offered as part of the units through this prospectus, except that the warrants previously issued are scheduled to expire on January 14, 2007. Upon the completion of this rights offer, BioTime will amend the expiration date of its outstanding warrants so that they will expire on October      , 2010.

Transfer Agent, Warrant Agent, and Registrar

      The transfer agent, warrant agent, and registrar for the common shares and warrants is American Stock Transfer and Trust Company, 6201 15^th Avenue, Brooklyn, New York 10038.

RESALE OF SHARES AND WARRANTS

      The Guarantors have advised us that they may hold for investment purposes any common shares and warrants they acquire, or they may sell common shares and warrants from time at prevailing market prices, or at prices related to the prevailing market price, or in privately negotiated transactions. They also may sell common shares in connection with the exercise of their warrants or they may hold those shares for investment purposes and sell them at later date.

      The Guarantors will bear all broker-dealer commissions payable in connection with the sale of their common shares and warrants. Broker-dealers who acquire common shares or warrants from the Guarantors as principals may resell the shares and warrants from time to time in the over-the-counter market, or in negotiated transactions at prevailing market prices, or at negotiated prices, and may receive usual and customary commissions from the purchasers of the shares and warrants.

      The Guarantors have advised us that during the time that they may be engaged in a distribution of their common shares and warrants they will (a) not engage in any stabilization activity in connection with BioTime securities, (b) cause to be furnished to each broker through whom their shares or warrants may be offered the number of copies of this prospectus required by the broker, and (c) not bid for or purchase any BioTime securities or rights to acquire BioTime securities, or attempt to induce any person to do so, other than as permitted under the Securities Exchange Act of 1934, as amended. The Guarantors and any broker-dealers who participate in the sale of their common shares and warrants are deemed to be “underwriters” as defined in the Securities Act. Any commissions paid or any discounts or concessions allowed to any broker-dealers in connection with the sale of the common shares and warrants, and any profits received on the resale of any shares and warrants purchased by broker-dealers as principals, may be deemed to be underwriting discounts and commissions under the Securities Act.

LEGAL MATTERS

      The validity of the rights, common shares, and warrants will be passed upon for BioTime by Lippenberger, Thompson, Welch, Soroko & Gilbert LLP, San Francisco and Corte Madera, California.

EXPERTS

      The financial statements incorporated by reference in this prospectus have been audited by BDO Seidman, LLP, independent certified public accountants, to the extent and for the periods set forth in their report incorporated herein by reference, and are incorporated herein in reliance upon such report given upon the authority of said firm as experts in accounting and auditing.

ADDITIONAL INFORMATION ABOUT BIOTIME

      This prospectus is accompanied by a copy of our Annual Report on Form 10-K for the year ended December 31, 2004 and our Quarterly Report on Form 10-Q for the three months ended June 30, 2005, which contain important information about us.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

      BioTime’s Annual Report on Form 10-K for the fiscal year ended December 31, 2004, Quarterly Reports on Form 10-Q for the three months ended March 31, 2005 and for the three months ended June 30, 2005, Current Reports on From 8-K filed with the Securities and Exchange Commission on April 1, 2005, April 27, 2005, June 17, 2005, and July 6, 2005, and all other reports filed by BioTime pursuant to Sections 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act of 1934, as amended, since the end of the fiscal year covered by such Form 10-K are hereby incorporated into this prospectus by reference. Descriptions of the common shares and warrants contained in Registration Statements on Form 8-A filed under the Securities Exchange Act of 1934, as amended, are also incorporated into this prospectus by reference. BioTime will provide without charge to each person, including any beneficial owner, to whom a prospectus is delivered, upon written or oral request of such person, a copy of any and all of the information that has been incorporated by reference but not delivered with this prospectus. Such requests may be addressed to the Secretary of BioTime at 6211 Hollis Street, Emeryville, California 94608; Telephone: (510) 350-2940.

      BioTime is subject to the informational requirements of the Securities Exchange Act of 1934, as amended, and in accordance therewith files quarterly, annual, and current reports and proxy statements and other information with the Securities and Exchange Commission. The public may read and copy any materials

BioTime files with Securities and Exchange Commission at the Commission’s Public Reference Room at 450 Fifth Street, N.W., Washington, D.C. 20549. The public may obtain information on the operation of the Public Reference Room by calling the Commission at 1-800-SEC-0330.

      The Commission maintains an Internet site that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the Commission. The address of such site is http://www.sec.gov.

ADDITIONAL INFORMATION

      BioTime has filed with the Securities and Exchange Commission, 450 Fifth Street, N.W., Washington, D.C. a registration statement on Form S-2 under the Securities Act of 1933, as amended, for the registration of the securities offered hereby. This prospectus, which is part of the registration statement, does not contain all of the information contained in the registration statement. For further information with respect to BioTime and the securities offered hereby, reference is made to the registration statement, including the exhibits thereto, which may be inspected, without charge, at the Office of the Securities and Exchange Commission, or copies of which may be obtained from the Commission in Washington, D.C. upon payment of the requisite fees. Statements contained in this prospectus as to the content of any contract or other document referred to are not necessarily complete. In each instance reference is made to the copy of the contract or other document filed as an exhibit to the registration statement, and each such statement is qualified in all respects by reference to the exhibit.

APPENDIX A

Expiration Date                     , 2005

THIS SUBSCRIPTION CERTIFICATE MAY BE USED TO SUBSCRIBE FOR UNITS OR MAY BE ASSIGNED OR SOLD. FULL INSTRUCTIONS APPEAR ON THE BACK OF THIS SUBSCRIPTION CERTIFICATE.

REGISTERED OWNER:

The registered owner of this Subscription Certificate, named above, or assignee, is entitled to the number of rights to subscribe for units consisting of one common share, no par value, and one warrant to purchase one common share of BioTime, Inc. shown above, in the ratio of one unit for each five rights held, and upon the terms and conditions and at the price for each unit specified in the Prospectus dated                     , 2005.

DATE: 

 

 2005

BIOTIME, INC.

SECRETARY

Countersigned: American Stock Transfer & Trust Company (Brooklyn, N.Y.) Subscription Agent

Authorized Signature

If you exercise fewer than all the rights represented by this Subscription Certificate, the subscription agent will issue a new Subscription Certificate representing the balance of the unexercised rights, provided that the subscription agent has received your properly completed and executed Subscription Certificate and payment prior to 5:00 p.m., New York time, on                     , 2005. No new Subscription Certificates will be issued after that date.

IMPORTANT: Complete appropriate form on reverse

BIOTIME, INC.

VICE PRESIDENT; MEMBER, OFFICE OF

THE PRESIDENT

Expiration Date:                    , 2005

PLEASE COMPLETE ALL APPLICABLE INFORMATION

TO SELL: If I have checked either the box on line C or the box on line D, I authorize the sale of Rights by the subscription agent according to the procedures described in the Prospectus. The check for the proceeds of sale will be mailed to the address of record.

Please check below:

Signature of Subscriber(s)/Seller(s):                                    

Please provide your telephone number: Day (     )                                         Evening (     )                              

Social Security Number or Tax ID Number:                                                   

SECTION II: TO TRANSFER RIGHTS: (except pursuant to C and D above)

For value received,                    of the Rights represented by this Subscription Certificate are assigned to

The signature(s) must correspond with the name(s) as written upon the face of this Subscription Certificate, in every particular, without alteration.

IMPORTANT: For transfer, a signature guarantee must be provided by an eligible financial institution which is a participant in a recognized signature guarantee program.

SIGNATURE GUARANTEED BY:

PROCEEDS FROM THE SALE OF RIGHTS MAY BE SUBJECT TO WITHHOLDING OF U.S. TAXES UNLESS THE SELLER’S CERTIFIED U.S. TAXPAYER IDENTIFICATION NUMBER (OR CERTIFICATION REGARD-ING FOREIGN STATUS) IS ON FILE WITH THE SUBSCRIPTION AGENT AND THE SELLER IS NOT OTHERWISE SUBJECT TO U.S. BACKUP WITHHOLDING.

APPENDIX B

[Form of Notice of Guaranteed Delivery]

NOTICE OF GUARANTEED DELIVERY OF SUBSCRIPTION RIGHTS AND

THE SUBSCRIPTION PRICE FOR UNITS OF BIOTIME, INC.

SUBSCRIBED FOR IN THE RIGHTS OFFER

      As set forth in the Prospectus under “The Rights Offer — Payment for Units,” this form or one substantially equivalent may be used as a means of effecting subscription for all units of BioTime, Inc. subscribed for in the rights offer. Such form may be delivered by hand or sent by facsimile transmission, overnight courier or mail to the Subscription Agent.

The Subscription Agent is:

American Stock Transfer & Trust Company

DELIVERY OF THIS INSTRUMENT TO AN ADDRESS, OR TRANSMISSION OF

INSTRUCTIONS VIA A TELECOPY OR FACSIMILE NUMBER, OTHER THAN ASSET FORTH ABOVE, DOES NOT CONSTITUTE A VALID DELIVERY

      The New York Stock Exchange member firm or bank or trust company which completes this form must communicate the guarantee and the number of units subscribed for to the Subscription Agent and must deliver this Notice of Guaranteed Delivery guaranteeing delivery of a properly completed and executed Subscription Certificate (which certificate must then be delivered by the close of business on the third business day after the expiration date, as defined in the Prospectus) to the Subscription Agent prior to 5:00 p.m., New York time, on the expiration date (                    , 2005, unless extended). Failure to do so will result in a forfeiture of the rights.

GUARANTEE

      The undersigned, a member firm of the New York Stock Exchange or a bank or trust company, guarantees delivery to the Subscription Agent by the close of business (5:00 p.m., New York time) on the third business day after the expiration date (                    , 2005, unless extended) of a properly completed and executed Subscription Certificate as subscription for such units as indicated herein or in the Subscription Certificate.

      Please note that if you are guaranteeing for over-subscription Units, and are a DTC participant, you must also execute and forward to American Stock Transfer & Trust Company a Nominee Holder Over-Subscription Exercise Form.

   PLEASE NOTE THAT IF YOU ARE GUARANTEEING FOR OVER-SUBSCRIPTION UNITS AND ARE A DTC PARTICIPANT, YOU MUST ALSO EXECUTE AND FORWARD TO THE SUBSCRIPTION AGENT A NOMINEE HOLDER OVER-SUBSCRIPTION EXERCISE FORM.

APPENDIX C

[Form of Nominee Holder Over-Subscription Exercise Form]

BIOTIME, INC. RIGHTS OFFER NOMINEE HOLDER OVER-SUBSCRIPTION

EXERCISE FORM PLEASE COMPLETE ALL APPLICABLE INFORMATION

      THIS FORM IS TO BE USED ONLY BY NOMINEE HOLDERS TO EXERCISE THE OVER-SUBSCRIPTION PRIVILEGE IN RESPECT OF RIGHTS THAT WERE EXERCISED AND DELIVERED THROUGH THE FACILITIES OF A COMMON DEPOSITORY. ALL OTHER EXERCISES OF OVER-SUBSCRIPTION PRIVILEGES MUST BE EFFECTED BY THE DELIVERY OF THE SUBSCRIPTION CERTIFICATES.

      THE TERMS AND CONDITIONS OF THE RIGHTS OFFER ARE SET FORTH IN BIOTIME’S PROSPECTUS DATED                     , 2005 (THE “PROSPECTUS”) AND ARE INCORPORATED HEREIN BY REFERENCE. COPIES OF THE PROSPECTUS ARE AVAILABLE UPON REQUEST FROM BIOTIME.

      VOID UNLESS RECEIVED BY THE SUBSCRIPTION AGENT WITH PAYMENT IN FULL BY 5:00 P.M., NEW YORK TIME, ON                     , 2005, UNLESS EXTENDED BY BIOTIME (THE “EXPIRATION DATE”).

      1. The undersigned hereby certifies to the Subscription Agent that it is a participant in [Name of Depository] (the “Depository”) and that it has either (i) exercised all of the rights and delivered such exercised rights to the Subscription Agent by means of transfer to the Depository Account of BioTime, Inc., or (ii) delivered to the Subscription Agent a Notice of Guaranteed Delivery in respect of the exercise of the rights and will deliver the rights called for in such Notice of Guaranteed Delivery to the Subscription Agent by means of transfer to such Depository Account of BioTime, Inc.

      2. The undersigned hereby exercises the over-subscription privilege to purchase, to the extent available, units and certifies to the Subscription Agent that such over-subscription privilege is being exercised for the account or accounts of persons (which may include the undersigned) on whose behalf all rights have been exercised.(*)

      3. The undersigned understands that payment of the subscription price of $0.50 per unit for each unit subscribed for pursuant to the over-subscription privilege must be received by the Subscription Agent at or before 5:00 p.m., New York time, on the Expiration Date, and represents that such payment, in the aggregate amount of $           either (check appropriate box):

BIOTIME, INC. BENEFICIAL OWNER CERTIFICATION

      The undersigned, a bank, broker or other nominee holder of rights (“Rights”) to purchase Units of BioTime, Inc. (“BioTime”) pursuant to the Rights Offer described and provided for in BioTime’s Prospectus dated                     , 2005 (the “Prospectus”) hereby certifies to BioTime and to American Stock Transfer & Trust Company, as Subscription Agent for such Rights Offer, that for each numbered line filled in below the undersigned has exercised, on behalf of the beneficial owner thereof (which may be the undersigned), the number of Rights specified on such line, and such beneficial owner wishes to subscribe for the purchase of additional Units pursuant to the over-subscription privilege (as defined in the Prospectus), in the amount set forth in the third column of such line:

          No dealer, salesperson or other person has been authorized in connection with this offering to give any information or to make any representations other than those contained in this Prospectus. This Prospectus does not constitute an offer or a solicitation in any jurisdiction to any person to whom it is unlawful to make such an offer or solicitation. Neither the delivery of this Prospectus nor any sale made hereunder shall, under any circumstances, create an implication that there has been no change in the circumstances of BioTime or the facts herein set forth since the date hereof.

TABLE OF CONTENTS

BIOTIME, INC.

3,574,290 Units Issuable Upon the

Exercise of Subscription Rights

1,787,145 Units Issuable to Fill

Excess Over-Subscriptions

5,361,435 Common Shares Issuable

Upon Exercise of Warrants

Each Unit Consists of One

Common Share and One Warrant

PROSPECTUS

                    , 2005

PART II.

INFORMATION NOT REQUIRED IN PROSPECTUS

      The estimated expenses of the Registrant in connection with the issuance and distribution of the securities being registered hereby are as follows:

      Section 317 of the California Corporations Code permits indemnification of directors, officers, employees and other agents of corporations under certain conditions and subject to certain limitations. In addition, Section 204(a)(10) of the California Corporations Code permits a corporation to provide, in its articles of incorporation, that directors shall not have liability to the corporation or its shareholders for monetary damages for breach of fiduciary duty, subject to certain prescribed exceptions. Article Four of the Articles of Incorporation of the Registrant contains provisions for the indemnification of directors, officers, employees and other agents within the limitations permitted by Section 317 and for the limitation on the personal liability of directors permitted by Section 204(b)(10), subject to the exceptions required thereby.

      Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers, and controlling persons of the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than payment by the Registrant of expenses incurred or paid by a director, officer or controlling person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the Registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by final adjudication of such issue.

      The undersigned registrant hereby undertakes:

      The undersigned undertakes that:

SIGNATURES

      Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-2 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Emeryville, State of California on September 1, 2005.

      Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

EXHIBIT INDEX

Exhibit 1

STAND-BY PURCHASE AGREEMENT

September 1, 2005

BioTime, Inc.

6121 Hollis Street

Emeryville, California 94608

      BioTime, Inc., a California corporation (the “Company”) and each of the persons named on Schedule I (the “Guarantors”) hereby agree as follows:

      1.     Rights Offer.

      1.1     Subscription Rights. The Company will distribute to the holders of its common shares, no par value subscription rights (“Rights”) entitling each holder to subscribe for and purchase one “Unit” for every three Rights held (the “Rights Offer”). Each “Unit” will consist of one new common share (the “Shares”) and one warrant to purchase an additional common share (the “Warrants”). The subscription price per Unit payable upon the exercise of the Rights shall be $0.50 (the “Subscription Price”).

      (a) Each person who is a holder of record of common shares on the record date fixed by the Company will receive one Right for each common share owned on the record date. Beneficial owners of common shares held in the name of Cede & Co. as nominee for The Depository Trust Company, or in the name of any other depository or nominee, on the record date, will also receive Rights. The Rights will expire at 5:00 p.m. New York City time twenty-one days after the commencement of the Rights Offer or on such later date as the Company may determine (the “Expiration Date”).

      1.2     Over-Subscription Privilege. Shareholders who fully exercise the Rights initially issued to them will be entitled to the additional privilege of subscribing for and purchasing any Units not acquired by other holders of Rights (the “Over-Subscription Privilege”). The terms and conditions of the Over-Subscription Privilege are more fully set forth in the Prospectus included as a part of the Registration Statement (as defined below). The Company may also issue and sell additional Units to fill excess over-subscriptions after all of the Rights are exercised through the primary subscription or through the over-subscription privilege (“Excess Over-Subscription Units”).

      1.3     Warrants. Each full Warrant will entitle the holder to purchase one common share at a price of $2.00 per share. The Warrants will expire during October 2010, and may not be exercised after that date. The Company may redeem the Warrants in accordance with the provisions of the Warrant Agreement by paying $.05 per Warrant if the closing price of the common shares on a national securities exchange or the Nasdaq Stock Market exceeds 200% of the exercise price of the Warrants for any 20 consecutive trading days. The Warrants may not be exercised after the last business day prior to the redemption date.

      1.4     Purchase of Units. Each Guarantor agrees to purchase from the Company in accordance with the terms and conditions of this Agreement, an amount of Units that remain unsold through the exercise of the Rights and the over-subscription privilege determined by dividing the amount of such Guarantor’s Purchase Commitment shown on Schedule I by the Subscription Price. Payment of the Subscription Price for the Units purchased by Guarantors shall be made by tendering to the Company cash in the principal amount of the aggregate Subscription Price to be paid.

      (a) If the aggregate Subscription Price of all Units that the Guarantors are required to purchase is less than $1,781,450, the Guarantors shall purchase their respective pro rata share of the Units to be purchased. A Guarantor’s pro rata share shall be the Guarantor’s Purchase Commitment divided by $1,781,450. The Guarantors will have no right or obligation to purchase Excess Over-Subscription Units. The Guarantors shall not be required to purchase a fractional Unit and no fractional Units shall be issued.

      (b) A Guarantor may assign some or all of their rights to purchase Units to one or more persons who are not parties to this Agreement, provided that (a) the Registration Statement (as defined below) is effective under the Securities Act (as defined below), (b) the assignor delivers to the assignee a current Prospectus (as defined below) at the time of the assignment, and (c) the assignee is not a member of the NASD or registered as a broker or dealer under the Securities Exchange Act of 1934, as amended. No such assignment shall relieve a Guarantor of his or her obligations under this Agreement.

      1.5     Escrow of Funds By Guarantors. To secure their respective obligations under this Agreement, the Guarantors shall enter into an escrow agreement with the Company and American Stock Transfer & Trust Company or an other financial institution approved by the Company and the Guarantors, as escrow agent, and shall deposit with the escrow agent an amount of good funds equal to the total amount of the Guarantor’s Purchase Commitment. On the Closing Date (as defined below) the escrow agent shall pay to the Company from funds held in escrow an amount equal to the total Subscription Price required to be paid by the Guarantors to purchase Units under this Agreement, net of the Guarantors’ respective share of the Guarantors’ Fee (as defined below).

      1.6     Registration Statement. The Company will prepare and file with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended, and the rules and regulations of the Commission thereunder (collectively, the “Securities Act”), a registration statement including a prospectus, relating to the Rights, Units, Shares, Warrants, and Warrant Shares. Such registration statement, as amended at the time it becomes effective, is referred to herein as the “Registration Statement.” The term “Prospectus” means the prospectus in the form first delivered to holders of record who receive Rights in the Rights Offer. Any reference in this Agreement to the Registration Statement or the Prospectus shall be deemed to refer to and include the documents incorporated by reference therein pursuant to Item 12 of Form S-2 under the Securities Act, as of the effective date of the Registration Statement or the date of the Prospectus, as the case may be, and any reference to “amend”, “amendment” or “supplement” with respect to the Registration Statement, or the Prospectus shall be deemed to refer to and include any documents filed after such date under the Securities Exchange Act of 1934, as amended, and the rules and regulations of the Commission thereunder (collectively, the “Exchange Act”) that are deemed to be incorporated by reference therein. Unless the context otherwise requires, the term “Warrants” means the Warrants issued as part of the Units and the Standby Guaranty Warrants issuable to the Guarantors under this Agreement. The term “Warrant Shares” means the common shares issuable upon the exercise of the Warrants. Capitalized terms used but not defined herein shall have the meanings given to such terms in the Registration Statement and the Prospectus.

      1.7     No Stabilization. The Guarantors will not (a) take, directly or indirectly, any action to, or that could reasonably be expected to, cause or result in any stabilization or manipulation of the price of the Units or Company common shares or warrants, or (b) bid for or purchase any BioTime securities or rights to acquire BioTime securities, or attempt to induce any person do so, other than as permitted under the Securities Exchange Act of 1934, as amended.. The Guarantors will cause to be furnished to each broker through whom their Shares, Warrants or Warrant Shares may be offered the number of copies of this prospectus required by the broker.

      2.     Representations and Warranties. The Company hereby represents and warrants to the Guarantors that:

      2.1     Corporate Organization. The Company is a corporation duly organized, validly existing and in good standing under the laws of its state of incorporation, and has the requisite corporate power and authority to own or lease its properties and to carry on its business as now being conducted. The Company is duly qualified as a foreign corporation to do business and is in good standing in every jurisdiction in which the property owned or leased by it or the nature of the business conducted by it makes such qualification necessary, except to the extent that the failure to be so qualified or in good standing would not have, individually or in the aggregate, a Material Adverse Effect. For purposes of this Agreement, “Material Adverse Effect” shall mean any material adverse effect on the business, operations, conditions (financial or otherwise), assets, results of operations or prospects of that entity individually or of the Company.

      2.2     Capitalization; Organizational Documents.

      (a) The authorized capital stock of the Company will consist immediately prior to the Closing of 40,000,000 common shares, no par value, of which 17,871,450 shares are issued and outstanding as of the date of this Agreement, and 1,000,000 preferred shares, of which no shares are issued and outstanding. All of the outstanding common shares have been duly and validly issued and are fully paid and nonassessable. Except as contemplated by the Registration Statement or as disclosed in the Company’s Form 10-K for the fiscal year ended December 31, 2004, or its Form 10-Q for the fiscal quarter ended June 30, 2005, as of the date of this Agreement, there are no outstanding options, warrants, scrip, rights to subscribe to, calls or commitments of any character whatsoever relating to, or securities or rights convertible into, any shares of capital stock of the Company, or contracts, commitments, understandings or arrangements by which the Company is or may become bound to issue additional shares of capital stock other than options that may be granted from time to time by the Company under its 2002 Stock Option Plan, as amended. Except for the Rights, when and as distributed by the Company, there are no preemptive rights or rights of first refusal or similar rights which are binding on the Company permitting any person to subscribe for or purchase from the Company shares of its capital stock pursuant to any provision of law, the Articles of Incorporation or the Company’s Bylaws or by agreement or otherwise.

      (b) Upon issuance of the Units and payment of the Subscription Price in accordance with the terms of this Agreement, the Shares so issued will be duly authorized, validly issued, fully paid and nonassessable, and free and clear of any restrictions on transfer preemptive rights other than any transfer restrictions under the Securities Act and applicable state securities or Blue Sky laws, and the Warrants will constitute the binding obligations of the Company, enforceable in accordance with their terms. When issued as provided in this Agreement, the Standby Guaranty Warrants will constitute the binding obligations of the Company, enforceable in accordance with their terms. When issued upon the exercise of the Warrants, the Warrant Shares shall be duly authorized, validly issued, fully paid and nonassessable, and free and clear of any restrictions on transfer preemptive rights other than any transfer restrictions under the Securities Act and applicable state securities or Blue Sky laws.

      2.3     Authorization; Enforcement. (a) The Company has the requisite corporate power and authority to enter into and perform its obligations under this Agreement and to issue, sell and perform its obligations with respect to the Rights, Units, Shares, Warrants, and Warrant Shares (b) the execution and delivery of this Agreement by the Company and the consummation of the transactions contemplated hereby have been duly authorized by the Company’s Board of Directors or a committee thereof and no further consent or authorization is required by the Company, its Board of Directors or its stockholders, and (c) this Agreement has been duly executed and delivered by the Company. No other corporate proceedings on the part of the Company are necessary to approve and authorize the execution and delivery of this Agreement and the issuance of the Rights, and the Shares and Warrants comprising the Units, the Standby Guaranty Warrants, and the Warrant Shares. This Agreement constitutes the valid and binding agreement of the Company enforceable against the Company in accordance with its terms, except as such enforceability may be limited by general principles of equity or applicable bankruptcy, insolvency, reorganization, moratorium, liquidation or similar laws relating to, or affecting generally, the enforcement of creditors’ rights and remedies, and except as enforcement of indemnification provisions may be limited under the Securities Act and applicable state securities or Blue Sky laws.

      2.4     No Conflicts. The execution, delivery and performance of this Agreement by the Company, and the consummation of the transactions contemplated hereby will not (a) result in a violation of the Articles of Incorporation or Bylaws of the Company, or (b) violate or conflict with, or result in a breach of, any provision of, or constitute a default (or an event which with notice or lapse of time or both would become a default) under, or give to others any rights of termination, amendment, acceleration or cancellation of, any note, bond, mortgage, agreement, license indenture or instrument to which the Company is a party, or result in the creation of any lien on or against any of the properties of the Company, or result in a violation of any statute, law, rule, regulation, writ, injunction, order, judgment or decree applicable to the Company or by which any property or asset of the Company is bound or affected, except where such violation, conflict, breach or other consequence would not have a Material Adverse Effect. Except as disclosed in the Registration Statement,

including any reports (“Exchange Act Reports”) filed under the Exchange Act incorporated by reference in the Registration Statement, the Company is not in violation of any term of or in default under its Articles of Incorporation or Bylaws or in violation of any material term of, or in default under, any material contract, agreement, mortgage, indebtedness, indenture, instrument, judgment, decree or order or any statute, rule or regulation applicable to the Company. Except as specifically contemplated by this Agreement, the Company is not required to obtain any consent, authorization or order of, or make any filing or registration with, any court or governmental or regulatory or self-regulatory agency in order for it to execute, deliver or perform any of its obligations under or contemplated by this Agreement in accordance with the terms hereof, other than (i) the Registration Statement and filings pursuant to state securities laws in connection with the distribution of the Rights, sale of the Units, exercise of the Warrants and resale of any Units and Warrant Shares acquired by the Guarantors, and (ii) filings, if any, required by the NASD. All consents, authorizations, orders, filings and registrations that the Company is required to obtain pursuant to the preceding sentence will have been obtained or effected on or prior to the date hereof.

      2.5     Exchange Act Reports; Financial Statements. (a) The Company has filed on a timely basis all Exchange Act Reports required to be filed under the Exchange Act. None of the Exchange Act Reports incorporated by reference in the Registration Statement, at the time they were filed (except those Exchange Act Reports that were subsequently amended), contained any untrue statement of a material fact or omitted to state a material fact required to be stated therein or necessary in order to make the statements therein, in light of the circumstances under which they were made, not misleading. As of their respective dates, the financial statements of the Company included in the Exchange Act Reports incorporated by reference in the Registration Statement complied as to form in all material respects with applicable accounting requirements and the published rules and regulations of the Commission or other applicable rules and regulations with respect thereto. Such financial statements have been prepared in accordance with generally accepted accounting principles applied on a consistent basis during the periods involved (except (a) as may be otherwise indicated in such financial statements or the notes thereto, or (b) in the case of unaudited interim statements, to the extent they may exclude footnotes or may be condensed or summary statements) and fairly present in all material respects the financial position of the Company as of the dates thereof and the results of its operations and cash flows for the periods then ended (subject, in the case of unaudited statements, to normal year-end audit adjustments).

      (b) Except as set forth in the Exchange Act Reports or in the Registration Statement, the Company has incurred no material liabilities of any kind, whether accrued, absolute, contingent or otherwise or entered into any material transactions except in the ordinary course of business. The other historical financial and statistical information with respect to the Company included in the Registration Statement present fairly in all material respects the information shown therein on a basis consistent with the audited and unaudited financial statements of the Company included in the Exchange Act Reports incorporated by reference in the Registration Statement. The Company does not know of any facts, circumstances or conditions materially adversely affecting its operations, earnings or prospects which have not been fully disclosed in the Registration Statement, including the Exchange Act Reports incorporated by reference in the Registration Statement.

      (c) BDO Seidman, LLP who have expressed their opinions with respect to the audited financial statements which form a part of the Company’s Annual Report on Form 10-K, as amended, incorporated in the Registration Statement, are independent accountants as required by the Securities Act and the rules and regulations thereunder.

      2.6     Litigation. All lawsuits and arbitrations proceedings known by the Company to be pending or threatened against the Company that would have a Material Adverse Effect on the Company are disclosed in the Exchange Act Reports. There is no action, suit, proceeding or investigation known to the Company that questions the validity of this Agreement or the right of the Company to execute, deliver and perform its obligations under this Agreement.

      2.7     Intellectual Property. The Company owns, or has the contractual right to use, sell or license all intellectual property necessary or required for the conduct of its business as presently conducted and as proposed to be conducted, including, without limitation, all trade secrets, processes, source code, licenses,

trademarks, service marks, trade names, logos, brands, copyrights, patents, franchises, domain names and permits. The Company has not received any communications alleging that the Company has violated or, by conducting its business presently conducted or as proposed to be conducted, violates or will violate any intellectual property rights of any other person or entity.

      2.8     Title to Property and Assets. The Company has good and marketable title to, or, in the case of leases and licenses, has valid and subsisting leasehold interests or licenses in, all of its properties and assets (whether real or personal, tangible or intangible) free and clear of any liens or other encumbrances, except for liens or other encumbrances that do not, individually or in the aggregate, have a Material Adverse Effect. With respect to property leased by the Company, the Company has a valid leasehold interest in such property pursuant to leases which are in full force and effect, and the Company is in compliance in all material respects with the provisions of such leases.

      2.9     Compliance with Laws. To the best of the Company’s knowledge, the Company is and has been in compliance in all material respects with all laws, rules, regulations, orders, judgments or decrees that are applicable to the Company, the conduct of its business as presently conducted, and the ownership of its property and assets (including, without limitation, all Environmental Laws (as defined below) and laws related to occupational safety, health, wage and hour, and employment discrimination), except where such violation or violations do not have a Material Adverse Effect. “Environmental Laws” means all federal, state, local and foreign laws, ordinances, treaties, rules, regulations, guidelines and permit conditions relating to contamination or pollution of the environment (including ambient air, surface water, ground water, land surface or subsurface strata) or the protection of human health and worker safety, including, without limitation, laws and regulations relating to transportation, storage, use, manufacture, disposal or release of, or exposure of employees or others to, Hazardous Materials (as defined below) or emissions, discharges, releases or threatened releases of Hazardous Materials. “Hazardous Materials” means any substance that has been designated by any governmental entity or by applicable Environmental Laws to be radioactive, toxic, hazardous or otherwise a danger to health or the environment, including, without limitation, PCBs, asbestos, petroleum, urea formaldehyde and all substances listed as hazardous substances pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as amended, or defined as a hazardous waste pursuant to the Resource Conservation and Recovery Act of 1976, as amended, and the regulations promulgated pursuant to Environmental Laws, but excluding office and janitorial supplies maintained in accordance with Environmental Laws.

      2.10     Licenses and Permits. The Company has obtained and maintains all federal, state, local and foreign licenses, permits, consents, approvals, registrations, authorizations and qualifications required to be maintained in connection with the operations of the Company as presently conducted, the lack of which could have a Material Adverse Effect, provided, that in the ordinary course of business, the Company will have to obtain applicable regulatory approvals required to market its products or new clinical uses of Company products. The Company is not in default in any material respect under any of such licenses, permits, consents, approvals, registrations, authorizations and qualifications.

      2.11     Related Entities. The Company does not presently own or control, directly or indirectly, any interest in any other subsidiary, corporation, association or other business entity. The Company is not a party to any joint venture, partnership or similar arrangement.

      2.12     Changes. Since June 30, 2005, the Company has operated its business in the ordinary course of business and, to the knowledge of the Company, there has not been, or the Company has not (as the case may be):

      2.13     Employee Benefit Plans. All “employee benefit plans,” as such term is defined in the Employee Retirement Income Security Act of 1974, as amended (“ERISA”), to which the Company has any liability or obligation, contingent or otherwise, comply in all material respects and have been maintained and administered in material compliance with ERISA, the Internal Revenue Code of 1986, as amended (the “Code”), and all other statutes, orders and governmental rules and regulations applicable to such employee benefit plans. The Company has not incurred any liability pursuant to ERISA or the penalty or excise tax provisions of the Code relating to employee benefit plans (as defined in ERISA), and no event, transaction or condition has occurred or exists that could reasonably be expected to result in the incurrence of any such liability by the Company, or in the imposition of any lien on any of the rights, properties or assets of the Company pursuant to ERISA or to such penalty or excise tax provisions of the Code. The Company does not maintain or contribute to, and has not maintained or contributed to, any “multiemployer plan,” as such term is defined in ERISA.

      2.14     Taxes. The Company has timely filed all tax returns and reports (federal, state and local) required to be filed and these returns and reports are true and correct in all material respects. The Company has paid all taxes and other assessments shown to be due on such returns or reports. Neither the Internal Revenue Service nor any state or local taxing authority has, during the past three (3) years, examined or informed the Company that it is in the process of examining any such tax returns and reports. The provision for taxes of the Company, as shown on the financial statements included in the most recent Exchange Act Report, is adequate for taxes due or accrued as of the date thereof and since that date the Company has provided adequate accruals in accordance with generally accepted accounting principals in its financial statements for any taxes incurred that have not been paid, whether or not shown as being due on any tax returns.

      2.15     Insurance. The Company has in full force and effect fire, casualty and liability insurance policies, with extended coverage, sufficient in amount (subject to reasonable deductibles) to allow the Company to replace any of its properties that might be damaged or destroyed to the extent and in the manner customary for companies in similar business similarly situated.

      2.16     Employees. (a) The Company does not have any collective bargaining agreements with any of its employees. There is no labor union organizing activity pending or, to the Company’s knowledge, threatened with respect to the Company. To the Company’s knowledge, no officer or key employee intends to terminate their employment with the Company, nor does the Company have a present intention to terminate the employment of any of the foregoing. All material employment arrangements existing or proposed to exist with the Company’s officers have been fully disclosed in the Registration Statement.

      (b) To the knowledge of the Company, if any existing full-time employee identified in the Registration Statement has entered into any non-competition, non-disclosure, confidentiality or other similar agreement with any party other than the Company, such employee is neither in violation thereof nor is expected to be in violation thereof as a result of the business conducted or expected to be conducted by the Company as described in the Registration Statement or such person’s performance of his obligations to the Company; and the Company has not received notice that any consultant or scientific advisor of the Company is in violation of any non-competition, non-disclosure, confidentiality or similar agreement.

      2.17     Material Contracts. All contracts, agreements, instruments, leases, licenses, arrangements and understandings to which the Company therein is a party or by which it may be bound required to be filed as exhibits to the Exchange Act Reports included in the Registration Statement or incorporated by reference therein have been so filed (the “Material Contracts”). The Material Contracts that have been filed as exhibits are complete and correct copies of the contracts, agreements, instruments, leases, licenses, arrangement, understanding or other documents of which they purport to be copies, except for portions of certain documents that were redacted under the Commission’s regulations pertaining to confidential treatment. The Material Contracts are valid and in full force and effect as to the Company, and, to the Company’s knowledge, to the other parties thereto. Except as otherwise disclosed herein or in the Exchange Act Reports, the Company is not in violation of, or default under (and there does not exist any event or condition which, after notice or lapse of time or both, would constitute such a default under), the Material Contracts, except to the extent that such violations or defaults, individually or in the aggregate, could not reasonably be expected to (a) affect the validity of this Agreement, (b) have a Material Adverse Effect, or (c) impair the ability of the Company to perform fully on a timely basis any material obligation which the Company has or will have under this Agreement. To the Company’s knowledge, except as set forth in the Exchange Act Reports, none of the other parties to any Material Contract are in violation of or default under any Material Contract in any material respect. The Company has not received any notice of cancellation or any written communication threatening cancellation of any Material Contract by any other party thereto.

      2.18     Customers and Suppliers. Except as set forth in the Exchange Act Reports, no customer or supplier that was material to the Company during the previous twenty-four (24) months has terminated, materially reduced or threatened to terminate or material reduce its purchases from or provision of products or services to the Company.

      2.19     Registration Statement and Prospectus. No order suspending the effectiveness of the Registration Statement has been issued by the Commission and no proceeding for that purpose has been initiated or threatened by the Commission. As of the applicable effective date of the Registration Statement and any amendment thereto, the Registration Statement complied, and will comply in all material respects, with the Securities Act, and did not and will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein not misleading; and as of the applicable filing date of the Prospectus and any amendment or supplement thereto and as of the Closing Date, the Prospectus will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided that the Company makes no

representation and warranty with respect to any statements or omissions made in reliance upon and in conformity with any Guarantor’s Information (as defined below).

      2.20     Transfer Taxes. On the Closing Date, all stock transfer or other taxes (other than income taxes) which are required to be paid in connection with the sale and transfer of the Units to be sold to the Guarantors hereunder will be, or will have been, fully paid or provided for by the Company and all laws imposing such taxes will be or will have been complied with.

      2.21     Contributions. The Company has not directly or indirectly, (i) made any unlawful contribution to any candidate for public office, or failed to disclose fully where required by law any contribution in violation of law, or (ii) made any payment to any federal or state governmental officer or official, or other person charged with similar public or quasi-public duties, other than payments required or permitted by the laws of the United States or any jurisdiction thereof.

      2.22     Investment Company. The Company is not an “investment company” or an “affiliated person” of, or “promoter” for an investment company, within the meaning of the Investment Company Act of 1940, as amended.

      2.23     Related Party Transactions. No transaction has occurred between or among the Company and its affiliates, officers or directors or any affiliate or affiliates of any such officer or director that is required to be described in the Company’s Exchange Act Reports that is not so described.

      2.24     Books, Records; and Financial Controls. The books, records and accounts of the Company accurately and fairly reflect, in reasonable detail, the transactions in, and dispositions of, the assets of, liabilities of, and the results of operations of, the Company, all to the extent required by generally accepted accounting principles. The Company maintains a system of internal accounting controls sufficient to provide reasonable assurances that (i) transactions are executed in accordance with management’s general or specific authorizations, (ii) transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles and to maintain asset accountability, (iii) access to assets is permitted only in accordance with management’s general or specific authorization and (iv) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences.

      3.     Cooperation with and Compensation of the Guarantors.

      3.1     Cooperation. The Company will cooperate with the Guarantors by making available to them such information as may be requested in making a reasonable investigation of the Company and its affairs and shall provide access to such employees as shall be reasonably requested. All non-public information provided by the Company to the Guarantors will be considered as confidential information and shall be maintained as such by the Guarantors, except as required by law, until the same becomes known to the public through no fault of the Guarantors.

      3.2     Fee. For the agreement of the Guarantors to purchase Units, if any, that remain unsold in the Rights Offer, on the Closing Date the Company shall pay to the Guarantors a fee in the amount of One Hundred Thirty-Two Thousand Dollars ($132,000) in cash (the “Guarantors’ Fee”), and shall issue to the Guarantors warrants, in the form attached as Exhibit A (the “Standby Guaranty Warrants”) to purchase 600,000 common shares at an exercise price per share of $2.00.

      (a) The Guarantors’ Fee and the Standby Guaranty Warrants shall be allocated among the Guarantors pro rata according to the ratio that each Guarantor’s Purchase Commitment bears to the total Purchase Commitments of all of the Guarantors as a group.

      (b) Payment of the Guarantor’s Fee will be made by wire transfer of good funds to such accounts as the respective payees may designate by written notice to the Company. The Guarantors’ Fee shall be paid, and the Standby Guaranty Warrants shall be issued, on the Closing Date even if the Rights Offer is fully subscribed such that the Guarantors purchase no Units under this Agreement.

      3.3     No Stabilization. The Company will not take, directly or indirectly, any action designed to or that could reasonably be expected to cause or result in any stabilization or manipulation of the price of its common shares.

      4.     Closing Procedures. Payment for the Units that remain unsold in the Rights Offer shall be made by delivering to the Company by 10:00 A.M. New York City time on the fifth business day after the Expiration Date, or at such other time on the same or such other date thereafter as the Guarantors and the Company may agree upon in writing (the “Closing Date”) cash, in the amount of the Subscription Price to be paid by Guarantors. The time and date of such payment for the Units is referred to herein as the “Closing Date.” Certificates evidencing the Shares and Warrants purchased shall be delivered or shall be available for delivery to the Guarantors at the offices of American Stock Transfer &Trust Company (the “Transfer Agent”) on the Closing Date, and, except for the Standby Guaranty Warrants, shall be so delivered upon confirmation of the payment of the Subscription Price. Such Shares and Warrants shall be registered in such names and in such denominations as the purchasers shall request in writing, or if so requested by the purchasers Shares and Warrants other than the Standby Guaranty Warrants may be registered by book-entry delivery through the facilities of The Depository Trust Company (“DTC”). All requests concerning the registration and denomination of certificates evidencing Shares and Warrants shall be delivered to the Company and the Transfer Agent not later than two full business days prior to the Closing Date, with any transfer taxes payable in connection with the sale of the Shares and Warrants duly paid by the purchasers. The certificates for the Shares and Warrants, unless delivered by book-entry through the facilities of DTC, will be made available for inspection by the Guarantors at the office of the Transfer Agent on the business day prior to the Closing Date. Any transfer taxes payable in connection with the issuance of Shares and Warrants in the name of a designee or assignee of a Guarantor shall be paid by such designee, assignee, or Guarantor.

      5.     Further Covenants. The Company hereby covenants and agrees that:

      5.1     Effectiveness of the Registration Statement. If not already effective, the Company will use its reasonable best efforts to cause the Registration Statement to become effective at the earliest possible time and, if required, will file the final Prospectus with the Commission within the time periods specified by Rule 424(b) and Rule 430A under the Securities Act and to file promptly all reports and any definitive proxy or information statements required to be filed by the Company with the Commission pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act subsequent to the date of the Prospectus and for so long as the delivery of a prospectus is required in connection with the Rights Offer or the offer or sale of the Units, Standby Guaranty Warrants, and Warrant Shares by the Guarantors; and the Company will furnish copies of the Prospectus to the Guarantors in New York City concurrent with the distribution of the Prospectus to Company shareholders who receive Rights.

      5.2     Delivery of Copies of Prospectus. The Company will deliver, at the expense of the Company, to the Guarantors during the applicable prospectus delivery period under the Securities Act, as many copies of the Prospectus (including all amendments and supplements thereto and documents incorporated by reference therein) as the Guarantors may reasonably request. The term “prospectus delivery period” means the period of time after the first date of the public offering of the Rights as a prospectus relating to the Rights and Units is required by law to be delivered in connection with sales of the Units (or the Shares and Warrants) by the Company or by the Guarantors.

      5.3     Amendments or Supplements. Before filing any amendment or supplement to the Registration Statement or the Prospectus, whether before or after the time that the Registration Statement becomes effective, the Company will furnish to the Guarantors a copy of the proposed amendment or supplement for review and will not file any such proposed amendment or supplement to which they reasonably object.

      5.4     Notice to the Guarantors. The Company will advise the Guarantors Holders promptly (i) if not already effective, when the Registration Statement has become effective; (ii) when any amendment to the Registration Statement has been filed or becomes effective; (iii) when any supplement to the Prospectus or any amendment to the Prospectus has been filed; (iv) of any request by the Commission for any amendment to the Registration Statement or any amendment or supplement to the Prospectus or the receipt of any comments from the Commission relating to the Registration Statement or any other request by the

Commission for any additional information; (v) of the issuance by the Commission of any order suspending the effectiveness of the Registration Statement or preventing or suspending the use of the Prospectus or the initiation or threatening of any proceeding for that purpose; (vi) of the occurrence of any event within the prospectus delivery period as a result of which the Prospectus as then amended or supplemented would include any untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances existing when the Prospectus is delivered to a purchaser, not misleading; and (vii) of the receipt by the Company of any notice with respect to any suspension of the qualification of the Rights and Units for offer and sale in any jurisdiction or the initiation or threatening of any proceeding for such purpose; and the Company will use its reasonable best efforts to prevent the issuance of any such order suspending the effectiveness of the Registration Statement, preventing or suspending the use of the Prospectus or suspending any such qualification of the Rights, Units, Shares or Warrants, and, if any such order is issued, will use its reasonable best efforts to obtain as soon as possible the withdrawal thereof.

      5.5     Ongoing Compliance of the Prospectus. If during the prospectus delivery period (i) any event shall occur or condition shall exist as a result of which the Prospectus as then amended or supplemented would include an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances existing when the Prospectus is delivered to a purchaser, not misleading or (ii) it is necessary to amend or supplement the Prospectus to comply with law, the Company will immediately notify the Guarantors thereof and forthwith prepare and file with the Commission and furnish to the Guarantors such amendments or supplements to the Prospectus as may be necessary so that the statements in the Prospectus as so amended or supplemented will not, in the light of the circumstances existing when the Prospectus is delivered to a purchaser, be misleading or so that the Prospectus will comply with law.

      5.6     Blue Sky Compliance. The Company will use its reasonable best efforts to qualify the Rights, Units, Standby Guaranty Warrants, and Warrant Shares for offer and sale under the securities or Blue Sky laws of such jurisdictions as the Guarantors shall reasonably request and will continue such qualifications in effect so long as required for the Guarantors to (a) sell the Shares, Warrants, and Standby Guaranty Warrants acquired under this Agreement, or (b) to exercise such Warrants and Standby Guaranty Warrants and sell the Warrant Shares; provided that the Company shall not be required to file any general consent to service of process other than a form U-2.

      5.7     Expenses. The Company shall pay all expenses incurred in connection with the preparation and printing of all necessary offering documents and instruments related to the Rights Offer and the issuance of the Units and Warrant Shares and will also pay the Company’s own expenses for accounting fees, legal fees and other costs involved with the Rights Offer. The Company will provide at its own expense such quantities of the Prospectus and other documents and instruments relating to the Rights Offer as the Guarantors may request. In addition, the Company will pay all reasonable filing fees, costs and legal fees for Blue Sky services and related filings and expenses of counsel with respect to Blue Sky qualifications.

      5.8     Registration of Shares and Warrants. The Company will include the Standby Guaranty Warrants and Warrant Shares issuable upon the exercise of the Standby Guaranty Warrants in the Registration Statement. The Company will use its reasonable best efforts to file such post-effective amendments to the Registration Statement as may be required to keep the Registration Statement in effect so as to permit the Guarantors to (a) exercise the Standby Guaranty Warrants and sell any Warrant Shares issued upon such exercise, (b) exercise any Warrants purchased under this Agreement and sell any Warrant Shares issued upon such exercise, and (c) sell any Units purchased pursuant to this Agreement. The Company will provide the Guarantors with copies of a current Prospectus required to fulfill the Guarantors’ prospectus delivery requirement in connection with the sale of the common shares issued upon the exercise of the Standby Guaranty Warrants and Shares and Warrants comprising any Units purchased pursuant to this Agreement.

      6.     Conditions of Obligations of the Guarantors. The obligations of the Guarantors to purchase the Units are subject to the fulfillment, on or before the Closing Date, of the following additional conditions.

      6.1     Registration Compliance; No Stop Order. The Registration Statement (or a post-effective amendment if required to be filed under the Securities Act) shall have become effective, no order suspending the

effectiveness of the Registration Statement shall be in effect, and no proceeding for such purpose shall be pending before or threatened by the Commission; the Prospectus shall have been timely filed with the Commission under the Securities Act and all requests by the Commission for additional information shall have been complied with.

      6.2     Representations and Warranties Correct. The representations and warranties of the Company shall be true and correct in all material respects when made and on the Closing Date as though made on and as of the Closing Date.

      6.3     Performance of Covenants. The Company shall have performed and complied in all material respects with all agreements, covenants and conditions required to be performed and complied with by it under this Agreement on or before the Closing Date.

      6.4     Capitalization. Immediately prior to the Closing Date, the Company will have an authorized capitalization and issued and outstanding securities consistent with the description in the Registration Statement.

      6.5     Officer’s Certificate. The Guarantors shall have received a certificate of an executive officer and of the Company, dated as of the Closing Date, certifying the fulfillment of the conditions set forth in this Section 6.

      6.6     Good Standing; Resolutions. The Company shall have delivered to the Guarantors (i) a good standing certificate from the Secretary of State of its jurisdiction of incorporation, and (ii) certified resolutions of the Company’s Board of Directors approving this Agreement and the transactions contemplated by this Agreement.

      6.7     Fees and Warrants. The Company shall have (i) paid the Guarantors’ Fee, and (ii) delivered to the Guarantors the Standby Guaranty Warrants.

      6.8     Corporate Proceedings. All proceedings taken at or prior to the Closing Date in connection with the authorization, issuance and sale of the Units will be reasonably satisfactory in form and substance to the Guarantors.

      6.9     Opinion of Counsel. The Guarantors shall have received an opinion of the Company’s counsel substantially in the form attached as Exhibit B.

      6.10     Delivery of Shares and Warrants. The Guarantors shall have received the certificates (or confirmation of book entry) evidencing any Shares and Warrants purchased by them, against payment of the Subscription Price.

      7.     Indemnification.

      7.1     Indemnification by the Company. The Company agrees to indemnify and hold harmless the Guarantors and each of their respective affiliates, directors and officers and each person, if any, who controls a Guarantor within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act from and against any and all losses, claims, damages and liabilities (including, without limitation, legal fees and other expenses incurred in connection with any suit, action or proceeding or any claim asserted, as such fees and expenses are incurred), joint or several, that arise out of, or are based upon, any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement or the Prospectus (or any amendment or supplement thereto), or caused by any omission or alleged omission to state therein a material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading, except insofar as such losses, claims, damages or liabilities arise out of, or are based upon, any untrue statement or omission or alleged untrue statement or omission made in reliance upon and in conformity with any information relating to the Guarantors furnished to the Company or approved by any Guarantor; provided, that the foregoing indemnity with respect to any Prospectus shall not inure to the benefit of the a Guarantor (or any affiliate of a Guarantor that assists a Guarantor in the sale of Shares and Warrants), or any person controlling any Guarantor, if a copy of the Prospectus (as then amended or supplemented) was not sent or given by or on behalf of the Guarantor to each

purchaser of Shares or Warrants asserting such losses, claims, damages or liabilities, at or prior to the written confirmation of the sale of the Shares and Warrants to such person, unless such failure to send or give a copy of the Prospectus is the result of noncompliance by the Company with Section 5.1 or 5.2 of this Agreement.

      7.2     Indemnification of the Company. Each Guarantor agrees to indemnify and hold harmless the Company, the Company’s directors, Company officers who signed the Registration Statement, each other Guarantor, and each person, if any, who controls the Company or another Guarantor within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act to the same extent as the indemnity set forth in Section 7.1 above, but only with respect to any losses, claims, damages or liabilities that arise out of, or are based upon, any untrue statement or omission or alleged untrue statement or omission made in reliance upon and in conformity with any written information relating to the Guarantor furnished to the Company or approved by the Guarantor for use in the Registration Statement and the Prospectus or any amendment or supplement thereto (“Guarantor’s Information”).

      7.3     Notice and Procedures. If any suit, action, proceeding (including any governmental or regulatory investigation), claim or demand shall be brought or asserted against any person in respect of which indemnification may be sought pursuant to the preceding paragraphs of this Section 7, such person (the “Indemnified Person”) shall promptly notify the person against whom such indemnification may be sought (the “Indemnifying Person”) in writing; provided that the failure to notify the Indemnifying Person shall not relieve it from any liability that it may have under this Section 7 except to the extent that it has been materially prejudiced (through the forfeiture of substantive rights or defenses) by such failure. If any such proceeding shall be brought or asserted against an Indemnified Person and it shall have notified the Indemnifying Person thereof, the Indemnifying Person shall retain counsel reasonably satisfactory to the Indemnified Person to represent the Indemnified Person and any others entitled to indemnification pursuant to this Section 7 that the Indemnifying Person may designate in such proceeding and shall pay the fees and expenses of such counsel related to such proceeding, as incurred. In any such proceeding, any Indemnified Person shall have the right to retain its own counsel, but the fees and expenses of such counsel shall be at the expense of such Indemnified Person unless (i) the Indemnifying Person and the Indemnified Person shall have mutually agreed to the contrary; (ii) the Indemnifying Person has failed within a reasonable time to retain counsel reasonably satisfactory to the Indemnified Person; (iii) the Indemnified Person shall have reasonably concluded that there may be legal defenses available to it that are different from or in addition to those available to the Indemnifying Person who is also a named party in such proceeding, or for other reasons representation of both parties by the same counsel would be inappropriate due to actual or potential conflicts of interest between them. It is understood and agreed that the Indemnifying Person shall not, in connection with any proceeding or related proceeding in the same jurisdiction, be liable for the fees and expenses of more than one separate firm for all Indemnified Persons, and that all such fees and expenses shall be paid or reimbursed as they are incurred. An Indemnifying Person shall not be liable for any settlement of any proceeding effected without its written consent, but if settled with such consent or if there be a final judgment for the plaintiff, the Indemnifying Person agrees to indemnify each Indemnified Person from and against any loss or liability by reason of such settlement or judgment. No Indemnifying Person shall, without the written consent of the Indemnified Person, effect any settlement of any pending or threatened proceeding in respect of which any Indemnified Person is or could have been a party and indemnification could have been sought hereunder by such Indemnified Person, unless such settlement (x) includes an unconditional release of such Indemnified Person, in form and substance reasonably satisfactory to such Indemnified Person, from all liability on claims that are the subject matter of such proceeding and (y) does not include any statement as to or any admission of fault, culpability or a failure to act by or on behalf of any Indemnified Person.

      7.4     Contribution. If the indemnification provided for in this Agreement is unavailable to an Indemnified Person or insufficient in respect of any losses, claims, damages or liabilities referred to therein, then each Indemnifying Person under, in lieu of indemnifying each Indemnified Person under this Agreement, shall contribute to the amount paid or payable by such Indemnified Person as a result of such losses, claims, damages or liabilities (i) in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and the Guarantors on the other from the offering of the Units or (ii) if the allocation provided by clause (i) is not permitted by applicable law, in such proportion as is appropriate to

reflect not only the relative benefits referred to in clause (i) but also the relative fault of the Company on the one hand and the Guarantors on the other in connection with the statements or omissions that resulted in such losses, claims, damages or liabilities, as well as any other relevant equitable considerations. The relative benefits received by the Company on the one hand and the Guarantors on the other shall be deemed to be in the same respective proportions as the net proceeds (before deducting expenses) received by the Company from the sale of the Units to the Guarantors, the Guarantors’ Fee, and the Guarantors’ discount bear to the aggregate Subscription Price of the Units purchased by the Guarantors under this Agreement. For the purpose of this Agreement the Guarantors’ discount shall be the excess, if any, of the market value of the Shares and Warrants purchased by the Guarantors on the Closing Date over the Subscription Price. The relative fault of the Company on the one hand and the Guarantors on the other shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company or by the Guarantors and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission.

      7.5     Limitation on Liability. The Company and the Guarantors agree that it would not be just and equitable if contribution pursuant to this Section 7 were determined by pro rata allocation or by any other method of allocation that does not take account of the equitable considerations referred to in Section 7.4 above. The amount paid or payable by an Indemnified Person as a result of the losses, claims, damages and liabilities referred to in Section 7.4 above shall be deemed to include, subject to the limitations set forth above, any legal or other expenses incurred by such Indemnified Person in connection with any such action or claim. Notwithstanding the provisions of this Section 7, in no event shall any Guarantor be required to contribute any amount in excess of the amount by which the total Guarantors’ Fee and Guarantors’ discounts received by the Guarantor with respect to the purchase Units exceeds the amount of any damages that the Guarantor has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation.

      7.6     Non-Exclusive Remedies. The remedies provided for in this Section 7 are not exclusive and shall not limit any rights or remedies which may otherwise be available to any Indemnified Person at law or in equity.

      8.     Termination.

      8.1     In addition to the other circumstances permitting termination set forth elsewhere in this Agreement (if any), this Agreement may be terminated by the Guarantors at any time prior to the Closing Date in the event that (i) any of the representations or warranties of the Company contained herein shall prove to have been false or misleading in any material respect when made, (ii) the Company shall have failed to perform any of its material obligations hereunder, (iii) the Company shall have terminated the Rights Offer prior to the Expiration Date, or (iv) there shall occur any event not occasioned by or arising out of or in connection with any breach or failure hereunder on the part of the Guarantors which would cause the offer or sale of the Units to the Guarantors as contemplated by this Agreement to violate the Securities Act or any applicable state securities or Blue Sky law. In the event of any such termination the Guarantors shall not be entitled to receive the Guarantors’ Fee and shall only be entitled to receive, as their exclusive remedy, one-half of the Standby Guaranty Warrants that they would have received had this Agreement not been so terminated; provided, that if the Guarantors terminate this Agreement under clause (i) or (ii) of this paragraph, the Guarantors, in the aggregate, shall also be entitled to receive, an amount equal to the documented out-of-pocket expenses incurred by the Guarantors in connection with this Agreement, not to exceed $15,000; provided, however, that a Guarantor shall not be entitled to receive any Guaranty Warrants or other fees or expense reimbursements if the Guarantor is in breach or default under this Agreement.

      8.2     The Rights Offer and this Agreement may be terminated by the Company at any time prior to the Expiration Date for any reason. In the event of any such termination the Guarantors shall not be entitled to receive the Guarantors’ Fee and shall only be entitled to receive, as their exclusive remedy, one-half of the

Standby Guaranty Warrants hat they would have received had this Agreement not been so terminated; provided, that if the Company terminates the Rights Offer prior to the Expiration Date, or if at the time the Company terminates this Agreement (i) any of the representations or warranties of the Company contained herein shall prove to have been false or misleading in any material respect when made, or (ii) the Company shall have failed to perform any of its material obligations hereunder, the Guarantors, in the aggregate, shall be also entitled to receive an amount equal to the documented out-of-pocket expenses incurred by the Guarantors in connection with this Agreement, not to exceed $15,000; provided, however, that a Guarantor shall not be entitled to receive any Guaranty Warrants or other fees if the Guarantor is in breach or default under this Agreement.

      9.     Survival.

      9.1     The obligations of the parties to pay any costs and expenses under this Agreement and to provide indemnification and contribution as provided herein shall survive any termination of this Agreement.

      9.2     The respective indemnities, agreements, representations, warranties and other statements of the Company set forth in or made pursuant to this Agreement will remain in full force and effect, regardless of any investigation made by or on behalf of, and regardless of any access to information by, the Company or the Guarantors, or any of their officers or directors or any controlling person thereof, and will survive the sale of the Shares.

      10.     Notices. All communications hereunder will be in writing and, except as otherwise expressly provided herein or after notice by one party to the other of a change of address, if sent to the Guarantors, will be mailed, delivered or telefaxed and confirmed to them at the addresses shown on Schedule  I, and if sent to the Company, will be mailed, delivered or telefaxed and confirmed to BioTime, Inc., 6121 Hollis Street, Emeryville, CA 94608 Attn Judith Segall, Vice President and Secretary, Facsimile No. (510) 845-7914, with a copy to Lippenberger, Thompson, Welch, Soroko & Gilbert LLP: 201 Tamal Vista Boulevard, Corte Madera, CA 94925, Attn: Richard Soroko, Esq., Facsimile No. (415) 927-5210.

      11.     Governing Law. This Agreement shall be governed by and construed in accordance with the laws of the State of California.

      12.     Counterparts. This Agreement may be signed in counterparts (which may include counterparts delivered by any standard form of telecommunication), each of which shall be an original and all of which together shall constitute one and the same instrument.

      13.     Amendments or Waivers. No amendment or waiver of any provision of this Agreement, nor any consent or approval to any departure therefrom, shall in any event be effective unless the same shall be in writing and signed by the parties hereto.

      14.     Headings. The headings herein are included for convenience of reference only and are not intended to be part of, or to affect the meaning or interpretation of, this Agreement.

      15.     Several Obligations. The obligations of the Guarantors under this Agreement are their respective several obligations, and are not joint and several obligations. No Guarantor shall be liable for the breach or default of any provision of this Agreement by another Guarantor.

      If the foregoing is in accordance with your understanding, please indicate your acceptance of this Agreement by signing in the space provided below.

SCHEDULE I

GUARANTOR PURCHASE COMMITMENTS

Exhibit 4.4

Expiration Date                     , 2005

THIS SUBSCRIPTION CERTIFICATE MAY BE USED TO SUBSCRIBE FOR UNITS OR MAY BE ASSIGNED OR SOLD. FULL INSTRUCTIONS APPEAR ON THE BACK OF THIS SUBSCRIPTION CERTIFICATE.

REGISTERED OWNER:

The registered owner of this Subscription Certificate, named above, or assignee, is entitled to the number of rights to subscribe for units consisting of one common share, no par value, and one warrant to purchase one common share of BioTime, Inc. shown above, in the ratio of one unit for each five rights held, and upon the terms and conditions and at the price for each unit specified in the Prospectus dated                     , 2005.

DATE: 

 

 2005

BIOTIME, INC.

SECRETARY

Countersigned: American Stock Transfer & Trust Company (Brooklyn, N.Y.) Subscription Agent

Authorized Signature

If you exercise fewer than all the rights represented by this Subscription Certificate, the subscription agent will issue a new Subscription Certificate representing the balance of the unexercised rights, provided that the subscription agent has received your properly completed and executed Subscription Certificate and payment prior to 5:00 p.m., New York time, on                     , 2005. No new Subscription Certificates will be issued after that date.

IMPORTANT: Complete appropriate form on reverse

BIOTIME, INC.

VICE PRESIDENT; MEMBER, OFFICE OF

THE PRESIDENT

Expiration Date:                    , 2005

PLEASE COMPLETE ALL APPLICABLE INFORMATION

TO SELL: If I have checked either the box on line C or the box on line D, I authorize the sale of Rights by the subscription agent according to the procedures described in the Prospectus. The check for the proceeds of sale will be mailed to the address of record.

Please check below:

Signature of Subscriber(s)/Seller(s):                                    

Please provide your telephone number Day (     )                                         Evening (     )                              

Social Security Number or Tax ID Number:                                                   

SECTION II: TO TRANSFER RIGHTS: (except pursuant to C and D above)

For value received,                    of the Rights represented by this Subscription Certificate are assigned to

The signature(s) must correspond with the name(s) as written upon the face of this Subscription Certificate, in every particular, without alteration.

IMPORTANT: For transfer, a signature guarantee must be provided by an eligible financial institution which is a participant in a recognized signature guarantee program.

SIGNATURE GUARANTEED BY:

PROCEEDS FROM THE SALE OF RIGHTS MAY BE SUBJECT TO WITHHOLDING OF U.S. TAXES UNLESS THE SELLER’S CERTIFIED U.S. TAXPAYER IDENTIFICATION NUMBER (OR CERTIFICATION REGARDING FOREIGN STATUS) IS ON FILE WITH THE SUBSCRIPTION AGENT AND THE SELLER IS NOT OTHERWISE SUBJECT TO U.S. BACKUP WITHHOLDING.

Exhibit 4.5

VOID AFTER 5:00 P.M. NEW YORK TIME,                     , 2010

[Insert number of Shares]

Shares of Common Stock

BIOTIME, INC.

COMMON STOCK PURCHASE WARRANTS

      This certifies that, for value received, [Insert name of Holder] or registered assigns (the “Holder”), is entitled to purchase from BioTime, Inc. a California corporation (the “Company”), at a purchase price per share [Insert Warrant Price determined pursuant to Sections 4 and 10 of the Warrant Agreement] (the “Warrant Price”), the number of its Common Shares, no par value per share (the “Common Stock”), shown above. The number of shares purchasable upon exercise of the Common Stock Purchase Warrants (the “Warrants”) and the Warrant Price are subject to adjustment from time to time as set forth in the Warrant Agreement referred to below. Outstanding Warrants not exercised prior to 5:00 p.m., New York time, on                     , 2010 shall thereafter be void.

      Subject to restriction specified in the Warrant Agreement, Warrants may be exercised in whole or in part by presentation of this Warrant Certificate with the Purchase Form on the reverse side hereof duly executed, which signature shall be guaranteed by a financial institution that is a participant in a recognized signature guarantee program., and simultaneous payment of the Warrant Price (or as otherwise set forth in Section 10.5 of the Warrant Agreement) at the principal office of the Warrant Agent. Payment of the Warrant Price shall be made in cash or by certified or bank cashier’s check in such amount as provided in Section 3 of the Warrant Agreement. As provided in the Warrant Agreement, the Warrant Price and the number or kind of shares which may be purchased upon the exercise of the Warrant evidenced by this Warrant Certificate are, upon the happening of certain events, subject to modification and adjustment.

      The Warrants evidenced by this Warrant Certificate may be redeemed by the Company, at its election, at any time if the closing price of the Common Stock on a national securities exchange (including the Nasdaq Stock Market National Market System), or the average bid price as quoted in Nasdaq Stock Market if the Common Stock is not listed on a national securities exchange, equals or exceeds 200% of the Warrant Price for any twenty (20) consecutive trading days ending not more than twenty (20) days prior to the date of the notice given pursuant to Section 6.2 of the Warrant Agreement. From and after the date specified by the Company for redemption of the Warrants (the “Redemption Date”), the Warrants evidenced by this Warrant Certificate shall no longer be deemed outstanding and all rights of the Holder of this Warrant Certificate shall cease and terminate, except for the right of the registered Holder to receive payment of the redemption price of five cents ($0.05) per Warrant Share upon presentation and surrender of this Warrant Certificate. The Redemption Date shall abate, and the notice of redemption shall be of no effect, if the closing price or average bid price of the Common Stock, as applicable under Section 6.1 of the Warrant Agreement, does not equal or exceed 120% of the Warrant Price on the Redemption Date and the five trading days immediately preceding the Redemption Date, but the right Company shall have the right to redeem the Warrants at a future date if the conditions set forth in Section 6.1 of the Warrant Agreement are subsequently met and a new notice setting a new Redemption Date is sent to Warrant holders.

      This Warrant Certificate is issued under and in accordance with a Warrant Agreement dated as of December 9, 2003, as amended                     , 2005, between the Company and the Warrant Agent named therein, and is subject to the terms and provisions contained in the Warrant Agreement, to all of which the Holder of this Warrant Certificate by acceptance of this Warrant Certificate consents. A copy of the Warrant Agreement may be obtained by the Holder hereof upon written request to the Company.

      Upon any partial exercise of the Warrant evidenced by this Warrant Certificate, there shall be issued to the Holder hereof a new Warrant Certificate in respect of the shares of Common Stock as to which the Warrant evidenced by this Warrant Certificate shall not have been exercised. This Warrant Certificate may be exchanged at the office of the Warrant Agent by surrender of this Warrant Certificate properly endorsed either separately or in combination with one or more other Warrant Certificates for one or more new Warrant Certificates evidencing the right of the Holder thereof to purchase the aggregate number of shares as were purchasable on exercise of the Warrants evidenced by the Warrant Certificate or Certificates exchanged. No fractional shares will be issued upon the exercise of any Warrant, but the Company will pay the cash value thereof determined as provided in the Warrant Agreement. This Warrant Certificate is transferable at the office of the Warrant Agent in the manner and subject to the limitations set forth in the Warrant Agreement.

      The Holder hereof may be treated by the Company, the Warrant Agent and all other persons dealing with this Warrant Certificate as the absolute owner hereof for any purpose and as the person entitled to exercise the rights represented hereby, or to the transfer hereof on the books of the Company, any notice to the contrary notwithstanding, and until such transfer on such books, the Company and the Warrant Agent may treat the Holder hereof as the owner for all purposes.

      Neither the Warrant nor this Warrant Certificate entitles any Holder to any of the rights of a stockholder of the Company.

      This Warrant Certificate shall not be valid or obligatory for any purpose until it shall have been countersigned by the Warrant Agent.*

DATED:

PURCHASE FORM

(To be executed upon exercise of Warrant)

To BioTime, Inc.:

      The undersigned hereby irrevocably elects to exercise the right of purchase represented by the within Warrant Certificate for, and to purchase thereunder,                      shares of Common Stock, as provided for therein, and tenders herewith payment of the Warrant Price in full in the form of cash or a certified or bank cashier’s check.

      Please issue a certificate or certificates for such shares of Common Stock in the name of, and pay any cash for any fractional share to:

(Please Print Name)

(Please Print Address)

(Social Security Number or

Other Taxpayer Identification Number)

(Signature)

And, if said number of shares shall not be all the shares purchasable under the within Warrant Certificate, a new Warrant Certificate is to be issued in the name of said undersigned for the balance remaining of the share purchasable thereunder less any fraction of a share paid in cash.

ASSIGNMENT

(To be executed only upon assignment of Warrant Certificate)

      For value received,                     hereby sells, assigns and transfers unto                     the within Warrant Certificate, together with all right, title and interest therein, and does hereby irrevocably constitute and appoint                     attorney, to transfer said Warrant Certificate on the books of the within-named Company, with full power of substitution in the premises.

Dated: 

 

Exhibit 4.7

Amendment of Warrant Agreement

Dated as of                     , 2005

      THIS AMENDMENT OF WARRANT AGREEMENT, dated as of                           , 2005, between BioTime, Inc., a California corporation (the “Company”), and American Stock Transfer & Trust Company (“Warrant Agent”) for the benefit of each registered holder of a Warrant described herein (“Holder”) amends that certain Warrant Agreement dated December 9, 2003 (the “Agreement”). The Company has previously issued 2,780,150 common share purchase warrants (the “Original Warrants”) governed by the Agreement. The Company proposes to issue additional common share purchase warrants (the “Additional Warrants”) to purchase up to an aggregate of 5,961,435 of its common shares, no par value (the “Common Stock”) as follows: (a) up to 3,574,290 upon the exercise of subscription rights (the “Rights”); (b) up to an additional 1,787,145 Warrants through the sale of up to 1,787,145 Units to fill excess over-subscriptions of Rights, and (c) 600,000 Warrants to certain persons named as Guarantors pursuant to a Standby Purchase Agreement between such persons and the Company (the “Standby Guaranty Warrants”). Each Unit will be comprised of one share of Common Stock and one Warrant. Each Right will entitle the holder thereof to purchase one “Unit” for every five (5) Rights held.

      In consideration of the foregoing and for the purpose of defining the terms and provisions of the Warrants and the respective rights and obligations thereunder of the Company and each Holder, the Company agrees that the Agreement is amended by as follows:

      Section 1. Issuance of Additional Warrants; Term of Additional Warrants.

      1.1     The Company is issuing and delivering to each person who purchases Units a Warrant to purchase a number of Warrant Shares equal to the number of Units purchased by such purchaser.

      1.2     The Company is issuing and delivering to the Guarantors under the Standby Guaranty Agreement an aggregate of 600,000 Standby Guaranty Warrants.

      Section 2. Warrants Covered by this Agreement. As used in the Agreement, as amended hereby, the term “Warrants” refers to all Warrants, including the Original Warrants, the Standby Guaranty Warrants, and the other Additional Warrants. The Original Warrants, the Standby Guaranty Warrants and the other Additional Warrants are identical in all respects. The shares of Common Stock issuable upon exercise of the Warrants are referred to herein as the “Warrant Shares.”

      Section 3. Expiration Date of Warrants. Subject to the terms of this Agreement, as amended hereby, a Holder of any Warrant (including any Warrants into which a Warrant may be divided) shall have the right, which may be exercised at any time prior to 5:00 p.m., New York Time on                     , 2010 (the “Expiration Date”), to purchase from the Company the number of fully paid and nonassessable Warrant Shares which the Holder may at the time be entitled to purchase upon exercise of any of such Warrant. So long as the Warrants are listed for trading on any national securities exchange, the Company will not extend the Expiration Date without first giving such securities exchange notice of such extension within the time required by the exchange, but in no event less than twenty (20) days prior notice.

      Section 4. Form of Warrant. The Warrants shall be represented by a certificate in substantially the form of Exhibit A hereto. The price per Warrant Share and the number of Warrant Shares issuable upon exercise of each Warrant are subject to adjustment upon the occurrence of certain events, all as provided in the Agreement. The Warrants shall be executed on behalf of the Company by its Chairman of the Board, President or one of its Vice Presidents, under its corporate seal reproduced thereon attested by its Secretary or any Assistant Secretary. The signature of any such officers on the Warrants may be manual or facsimile. Any Holder of a Warrant Certificate evidencing an Original Warrant may exchange the same at the office of the Warrant Agent for a Warrant Certificate in substantially the form of Exhibit A by surrender of the Original Warrant Certificate properly endorsed either separately or in combination with one or more other Warrant Certificates for one or more new Warrant Certificates evidencing the right of the Holder thereof to purchase the aggregate number of shares as were purchasable on exercise of the Warrants evidenced by the Warrant Certificate or Certificates exchanged.

      Section 5. Notices; Principal Office. Any notice pursuant to the Agreement, as amended hereby, by the Company or by any Holder to the Warrant Agent, or by the Warrant Agent or by any Holder to the Company, shall be in writing and shall be delivered in person, or mailed first class, postage prepaid (a) to the

Company, at its office, Attention: Secretary or (b) to the Warrant Agent, at its offices as designated at the time the Warrant Agent is appointed. The address of the principal office of the Company is 6121 Hollis Street, Emeryville, California 94608. Any notice mailed pursuant to the Agreement, as amended hereby, by the Company or the Warrant Agent to the Holders shall be in writing and shall be mailed first class, postage prepaid, or otherwise delivered, to such Holders at their respective addresses on the books of the Company or the Warrant Agent, as the case may be. Each party hereto and any Holder may from time to time change the address to which notices to it are to be delivered or mailed hereunder by notice to the other party.

      Section 6. Effect of Amendment. Except as amended hereby, all provisions of the Agreement shall remain in full force and effect.

      IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly executed, all as of the day and year first above written.

Name: Judith Segall

Exhibit A

VOID AFTER 5:00 P.M. NEW YORK TIME,                     , 2010

[Insert number of Shares]

Shares of Common Stock

BIOTIME, INC.

COMMON STOCK PURCHASE WARRANTS

      This certifies that, for value received, [Insert name of Holder] or registered assigns (the “Holder”), is entitled to purchase from BioTime, Inc. a California corporation (the “Company”), at a purchase price per share [Insert Warrant Price determined pursuant to Sections 4 and 10 of the Warrant Agreement] (the “Warrant Price”), the number of its Common Shares, no par value per share (the “Common Stock”), shown above. The number of shares purchasable upon exercise of the Common Stock Purchase Warrants (the “Warrants”) and the Warrant Price are subject to adjustment from time to time as set forth in the Warrant Agreement referred to below. Outstanding Warrants not exercised prior to 5:00 p.m., New York time, on                     , 2010 shall thereafter be void.

      Subject to restriction specified in the Warrant Agreement, Warrants may be exercised in whole or in part by presentation of this Warrant Certificate with the Purchase Form on the reverse side hereof duly executed, which signature shall be guaranteed by a financial institution that is a participant in a recognized signature guarantee program., and simultaneous payment of the Warrant Price (or as otherwise set forth in Section 10 of the Warrant Agreement) at the principal office of the Warrant Agent. Payment of the Warrant Price shall be made in cash or by certified or bank cashier’s check in such amount as provided in Section 3 of the Warrant Agreement. As provided in the Warrant Agreement, the Warrant Price and the number or kind of shares which may be purchased upon the exercise of the Warrant evidenced by this Warrant Certificate are, upon the happening of certain events, subject to modification and adjustment.

      The Warrants evidenced by this Warrant Certificate may be redeemed by the Company, at its election, at any time if the closing price of the Common Stock on a national securities exchange (including the Nasdaq Stock Market National Market System), or the average bid price as quoted in Nasdaq Stock Market if the Common Stock is not listed on a national securities exchange, equals or exceeds 200% of the Warrant Price for any twenty (20) consecutive trading days ending not more than twenty (20) days prior to the date of the notice given pursuant to Section 6.2 of the Warrant Agreement. From and after the date specified by the Company for redemption of the Warrants (the “Redemption Date”), the Warrants evidenced by this Warrant Certificate shall no longer be deemed outstanding and all rights of the Holder of this Warrant Certificate shall cease and terminate, except for the right of the registered Holder to receive payment of the redemption price of five cents ($0.05) per Warrant Share upon presentation and surrender of this Warrant Certificate. The Redemption Date shall abate, and the notice of redemption shall be of no effect, if the closing price or average bid price of the Common Stock, as applicable under Section 6.1 of the Warrant Agreement, does not equal or exceed 120% of the Warrant Price on the Redemption Date and the five trading days immediately preceding the Redemption Date, but the right Company shall have the right to redeem the Warrants at a future date if the conditions set forth in Section 6.1 of the Warrant Agreement are subsequently met and a new notice setting a new Redemption Date is sent to Warrant holders.

      This Warrant Certificate is issued under and in accordance with a Warrant Agreement dated as of December 9, 2003, as amended                     , 2005, between the Company and the Warrant Agent named therein, and is subject to the terms and provisions contained in the Warrant Agreement, to all of which the Holder of this Warrant Certificate by acceptance of this Warrant Certificate consents. A copy of the Warrant Agreement, as amended, may be obtained by the Holder hereof upon written request to the Company.

      Upon any partial exercise of the Warrants evidenced by this Warrant Certificate, there shall be issued to the Holder hereof a new Warrant Certificate in respect of the shares of Common Stock as to which the Warrants evidenced by this Warrant Certificate shall not have been exercised. This Warrant Certificate may be exchanged at the office of the Warrant Agent by surrender of this Warrant Certificate properly endorsed either separately or in combination with one or more other Warrant Certificates for one or more new Warrant Certificates evidencing the right of the Holder thereof to purchase the aggregate number of shares as were purchasable on exercise of the Warrants evidenced by the Warrant Certificate or Certificates exchanged. No fractional shares will be issued upon the exercise of any Warrant, but the Company will pay the cash value thereof determined as provided in the Warrant Agreement, as amended. This Warrant Certificate is transferable at the office of the Warrant Agent in the manner and subject to the limitations set forth in the Warrant Agreement, as amended.

      The Holder hereof may be treated by the Company, the Warrant Agent and all other persons dealing with this Warrant Certificate as the absolute owner hereof for any purpose and as the person entitled to exercise the rights represented hereby, or to the transfer hereof on the books of the Company, any notice to the contrary notwithstanding, and until such transfer on such books, the Company and the Warrant Agent may treat the Holder hereof as the owner for all purposes.

      Neither the Warrants nor this Warrant Certificate entitle any Holder to any of the rights of a stockholder of the Company.

      This Warrant Certificate shall not be valid or obligatory for any purpose until it shall have been countersigned by the Warrant Agent.*

DATED:

PURCHASE FORM

(To be executed upon exercise of Warrant)

To BioTime, Inc.:

      The undersigned hereby irrevocably elects to exercise the right of purchase represented by the within Warrant Certificate for, and to purchase thereunder,                      shares of Common Stock, as provided for therein, and tenders herewith payment of the Warrant Price in full in the form of cash or a certified or bank cashier’s check.

      Please issue a certificate or certificates for such shares of Common Stock in the name of, and pay any cash for any fractional share to:

(Please Print Name)

(Please Print Address)

(Social Security Number or

Other Taxpayer Identification Number)

(Signature)

And, if said number of shares shall not be all the shares purchasable under the within Warrant Certificate, a new Warrant Certificate is to be issued in the name of said undersigned for the balance remaining of the share purchasable thereunder less any fraction of a share paid in cash.

ASSIGNMENT

(To be executed only upon assignment of Warrant Certificate)

      For value received,                     hereby sells, assigns and transfers unto                     the within Warrant Certificate, together with all right, title and interest therein, and does hereby irrevocably constitute and appoint                     attorney, to transfer said Warrant Certificate on the books of the within-named Company, with full power of substitution in the premises.

Dated: 

 

Exhibit 4.8

VOID AFTER 5:00 P.M. NEW YORK TIME,                     , 2010

[Insert number of Shares]

Shares of Common Stock

BIOTIME, INC.

COMMON STOCK PURCHASE WARRANTS

      This certifies that, for value received, [Insert name of Holder] or registered assigns (the “Holder”), is entitled to purchase from BioTime, Inc. a California corporation (the “Company”), at a purchase price per share [Insert Warrant Price determined pursuant to Sections 4 and 10 of the Warrant Agreement] (the “Warrant Price”), the number of its Common Shares, no par value per share (the “Common Stock”), shown above. The number of shares purchasable upon exercise of the Common Stock Purchase Warrants (the “Warrants”) and the Warrant Price are subject to adjustment from time to time as set forth in the Warrant Agreement referred to below. Outstanding Warrants not exercised prior to 5:00 p.m., New York time, on                     , 2010 shall thereafter be void.

      Subject to restriction specified in the Warrant Agreement, Warrants may be exercised in whole or in part by presentation of this Warrant Certificate with the Purchase Form on the reverse side hereof duly executed, which signature shall be guaranteed by a financial institution that is a participant in a recognized signature guarantee program, and simultaneous payment of the Warrant Price (or as otherwise set forth in Section 10.5 of the Warrant Agreement) at the principal office of the Warrant Agent. Payment of the Warrant Price shall be made in cash or by certified or bank cashier’s check in such amount as provided in Section 3 of the Warrant Agreement. As provided in the Warrant Agreement, the Warrant Price and the number or kind of shares which may be purchased upon the exercise of the Warrant evidenced by this Warrant Certificate are, upon the happening of certain events, subject to modification and adjustment.

      This Warrant Certificate is issued under and in accordance with a Warrant Agreement dated as of December 9, 2003, as amended                     , 2005, between the Company and the Warrant Agent named therein, and is subject to the terms and provisions contained in the Warrant Agreement, to all of which the Holder of this Warrant Certificate by acceptance of this Warrant Certificate consents. A copy of the Warrant Agreement may be obtained by the Holder hereof upon written request to the Company.

      Upon any partial exercise of the Warrant evidenced by this Warrant Certificate, there shall be issued to the Holder hereof a new Warrant Certificate in respect of the shares of Common Stock as to which the Warrant evidenced by this Warrant Certificate shall not have been exercised. This Warrant Certificate may be exchanged at the office of the Warrant Agent by surrender of this Warrant Certificate properly endorsed either separately or in combination with one or more other Warrant Certificates for one or more new Warrant Certificates evidencing the right of the Holder thereof to purchase the aggregate number of shares as were purchasable on exercise of the Warrants evidenced by the Warrant Certificate or Certificates exchanged. No fractional shares will be issued upon the exercise of any Warrant, but the Company will pay the cash value thereof determined as provided in the Warrant Agreement. This Warrant Certificate is transferable at the office of the Warrant Agent in the manner and subject to the limitations set forth in the Warrant Agreement.

      The Holder hereof may be treated by the Company, the Warrant Agent and all other persons dealing with this Warrant Certificate as the absolute owner hereof for any purpose and as the person entitled to exercise the rights represented hereby, or to the transfer hereof on the books of the Company, any notice to the contrary notwithstanding, and until such transfer on such books, the Company and the Warrant Agent may treat the Holder hereof as the owner for all purposes.

      Neither the Warrant nor this Warrant Certificate entitles any Holder to any of the rights of a stockholder of the Company.

      This Warrant Certificate shall not be valid or obligatory for any purpose until it shall have been countersigned by the Warrant Agent.*

DATED:

PURCHASE FORM

(To be executed upon exercise of Warrant)

To BioTime, Inc.:

      The undersigned hereby irrevocably elects to exercise the right of purchase represented by the within Warrant Certificate for, and to purchase thereunder,                      shares of Common Stock, as provided for therein, and tenders herewith payment of the Warrant Price in full in the form of cash or a certified or bank cashier’s check.

      Please issue a certificate or certificates for such shares of Common Stock in the name of, and pay any cash for any fractional share to:

(Please Print Name)

(Please Print Address)

(Social Security Number or

Other Taxpayer Identification Number)

(Signature)

And, if said number of shares shall not be all the shares purchasable under the within Warrant Certificate, a new Warrant Certificate is to be issued in the name of said undersigned for the balance remaining of the share purchasable thereunder less any fraction of a share paid in cash.

ASSIGNMENT

(To be executed only upon assignment of Warrant Certificate)

      For value received,                     hereby sells, assigns and transfers unto                     the within Warrant Certificate, together with all right, title and interest therein, and does hereby irrevocably constitute and appoint                     attorney, to transfer said Warrant Certificate on the books of the within-named Company, with full power of substitution in the premises.

Dated: