Warrant Agreement

WARRANT AGREEMENT, dated as of May 13, 2009, between  BioTime, Inc., a California corporation (the “Company”), and the each registered holder of a Warrant described herein (a “Holder”).

Section 1.            Issuance of Warrants; Term of Warrants .  The Company is issuing and delivering the common share purchase warrants described herein (“Warrants”) to the purchasers of “Units” under certain Stock and Warrant Purchase Agreements.  Each Unit consists of one common share, no par value, and one Warrrant.  The Warrants shall be represented by a certificate in substantially the form of Exhibit A hereto.  Subject to the terms of this Agreement, a Holder of any of such 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 October 31, 2010 (the “Expiration Date”), to purchase from the Company, at the Warrant Price (as defined herein) then in effect, the number of fully paid and nonassessable common shares, no par value, of the Company (“Warrant Shares”) determined as provided in this Agreement and specified in such Warrant.

Section 2.            Form of Warrant .  The text of the Warrants and of the Purchase Form shall be substantially as set forth in Exhibit A attached 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 hereinafter provided.  The Warrants shall be executed on behalf of the Company by its Chief Executive Officer, 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, provided, however, that the signature of any such officers must be manual until such time as a warrant agent is appointed.

2.1        Signatures; Date of Warrants .  Warrants bearing the manual or facsimile signatures of individuals who were at any time the proper officers of the Company shall bind the Company, notwithstanding that such individuals or any one of them shall have ceased to hold such offices prior to the delivery of such Warrants or did not hold such offices on the date of this Agreement.  In the event that the Company shall appoint a warrant agent to act on its behalf in connection with the division, transfer, exchange or exercise of Warrants, the Warrants issued after the date of such appointment shall be dated as of the date of countersignature thereof by the warrant agent upon division, exchange, substitution or transfer.  Until such time as the Company shall appoint a warrant agent, Warrants shall be dated as of the date of execution thereof by the Company either upon initial issuance or upon division, exchange, substitution or transfer.

2.2        Countersignature of Warrants .  In the event that the Company shall appoint a warrant agent to act on its behalf in connection with the division, transfer, exchange or exercise of Warrants, the Warrants issued after the date of such appointment shall be countersigned by the warrant agent (or any successor to the warrant agent then acting as warrant agent) and shall not be valid for any purpose unless so countersigned.  Warrants may be countersigned, however, by the warrant agent (or by its successor as warrant agent hereunder) and may be delivered by the warrant agent, notwithstanding that the persons whose manual or facsimile signatures appear thereon as proper officers of the Company shall have ceased to be such officers at the time of such countersignature, issuance or delivery.  The warrant agent (if so appointed) shall, upon written

instructions of the  President, Chief Executive Officer, an Executive or Senior Vice President,  or the Chief Financial Officer of the Company, countersign, issue and deliver the Warrants and shall countersign and deliver Warrants as otherwise provided in this Agreement.

Section 3.            Exercise of Warrants; Listing .

               3.1          Exercise of Warrants .  A Warrant may be exercised upon surrender of the certificate or certificates evidencing the Warrants to be exercised, together with the form of election to purchase on the reverse thereof duly filled in and signed, which signature shall be guaranteed by  a financial institution that is a participant in a recognized signature guarantee program, to the Company at its principal office (or if appointed, the principal office of the warrant agent) and upon payment of the Warrant Price (as defined in and determined in accordance with the provisions of Section 4 and Section 10) to the Company (or if appointed, to the warrant agent for the account of the Company), for the number of Warrant Shares in respect of which such Warrants are then exercised.  Payment of the aggregate Warrant Price (defined in Section 4  herein) shall be made by bank wire transfer to the account of the Company, or in cash, or by certified or bank cashier’s check.

(a)           Subject to Section 5, upon the surrender of the Warrant and payment of the Warrant Price as aforesaid, the Company (or if appointed, the warrant agent) shall promptly cause to be issued and delivered to or upon the written order of the Holder and in such name or names as the Holder may designate, a certificate or certificates for the number of full Warrant Shares so purchased upon the exercise of such Warrant, together with cash, as provided in Section 12, in respect of any fractional Warrant Shares otherwise issuable upon such surrender.  Such certificate or certificates shall be deemed to have been issued and any person so designated to be named therein shall be deemed to have become a holder of record of such Warrant Shares as of the date of the surrender of such Warrants and payment of the Warrant Price, as aforesaid.  The rights of purchase represented by the Warrant shall be exercisable, at the election of the Holder thereof, either in full or from time to time in part and, in the event that a certificate evidencing the Warrant is exercised in respect of less than all of the Warrant Shares purchasable on such exercise at any time prior to the date of expiration of the Warrant, a new certificate evidencing the unexercised portion of the Warrant will be issued, and the warrant agent (if so appointed) is hereby irrevocably authorized to countersign and to deliver the required new Warrant certificate or certificates pursuant to the provisions of this Section 3 and Section 2.2, and the Company, whenever required by the warrant agent (if appointed), will supply the warrant agent with Warrant certificates duly executed on behalf of the Company for such purpose.

3.2            Listing of Shares on Securities Exchange; Exchange Act Registration .  The Company will promptly use commercially reasonable efforts to cause the Warrant Shares to be listed, subject to official notice of issuance, on all national securities exchanges on which the Common Stock is listed and whose rules and regulations require such listing, as soon as possible following the date hereof.  The Company will promptly notify the Holders in the event that the Company plans to register the Warrants with the Securities and Exchange Commission under the Securities Exchange Act of 1934, as amended (the “Exchange Act”).

Section 4.            Warrant Price .  Subject to any adjustments required by Section 10, the price per share at which Warrant Shares shall be purchasable upon exercise of a Warrant (as to any particular Warrant, the “Warrant Price”) shall be Two Dollars ($2.00) per share.

Section 5.            Payment of Taxes .  The Company will pay all documentary stamp taxes, if any, attributable to the initial issuance of Warrant Shares upon the exercise of Warrants; provided, however, that the Company shall not be required to pay any tax or taxes which may be payable in respect of any transfer involved in the issue or delivery of any Warrant or certificates for Warrant Shares in a name other than that of the registered Holder of such Warrants.

Section 6.            Redemption of Warrants.

              6.1          Right to Redeem . The Warrants may be redeemed by the Company, at its election, at any time if (a) a registration statement that includes the Warrants and Warrant Shares is then effective under the Securities Act of 1933, as amended, and (b) the closing price of the Common Stock of the Company on a national securities exchange or the Nasdaq Stock Market equals or exceeds 200% of the Warrant Price for any fifteen (15) consecutive trading days ending not more than thirty (30) days prior to the date of the notice given pursuant to Section 6.2.

6.2         Notice of Redemption .  Notice of proposed redemption of the Warrants shall be sent by or on behalf of the Company, by first class mail, postage prepaid, to the Holders of record of the Warrants at the addresses of such Holders appearing in the records of the Company or the warrant agent, if any.  Such notice shall be sent not less than twenty (20) days prior to the date fixed by the Company for redemption (the “Redemption Date”).  Such notice shall notify the Holder of the Warrants that the Company will redeem the Warrants, and shall state (i) the date of redemption, (ii) the redemption price, (iii) the place or places at which the redemption price shall be paid upon presentation and surrender of the Warrants, and (iv) the name and address of the warrant agent, if any, and the name and address of any bank or trust company appointed by the Company to receive and disburse the redemption price.

6.3         Effect of Redemption .  From and after the Redemption Date, the Warrants shall no longer be deemed outstanding and all rights of the Holder of the Warrants shall cease and terminate, except for the right of the registered Holder to receive payment of the redemption price of one cent ($0.01) per Warrant Share upon presentation and surrender of the Warrants.

6.4         Abatement of Redemption .  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 of the Company, as applicable under Section 6.1, does not equal or exceed 120% of the Warrant Price on the Redemption Date and each of the five trading days immediately preceding the Redemption Date, but the Company shall have the right to redeem the Warrants at a future date if the conditions set forth in Section 6.1 are subsequently met and a new notice setting a new Redemption Date is sent to Warrant holders as provided in Section 6.2.

Section 7.            Transferability of Warrants .

7.1         Registration .  Each Warrant shall be numbered and shall be registered on the books of the Company (the “Warrant Register”) as issued.  The Company and the warrant agent (if appointed) shall be entitled to treat the Holder of any Warrant as the owner in fact thereof for all purposes and shall not be bound to recognize any equitable or other claim or interest in such Warrant on the part of any other person, and shall not be liable for any registration of transfer of any Warrant which is registered or to be registered in the name of a fiduciary or the nominee of a fiduciary upon the instruction of such fiduciary, unless made with the actual knowledge that a fiduciary or nominee is committing a breach of trust in requesting such registration or transfer, or with such knowledge of such facts that its participation therein amounts to bad faith.

7.2         Restrictions on Exercise and Transfer .  The Warrants may not be exercised, sold, pledged, hypothecated, transferred or assigned, in whole or in part, unless a registration statement under the Securities Act of 1933, as amended (the “Act”), and under any applicable state securities laws is effective therefor or, an exemption from such registration is then available.  Any exercise, sale, pledge, hypothecation, transfer, or assignment in violation of the foregoing restriction shall be deemed null and void and of no binding effect.  The Company shall be entitled to obtain, as a condition precedent to its issuance of any certificates representing Warrant Shares or any other securities issuable upon any exercise of a Warrant, a letter or other instrument from the Holder containing such covenants, representations or warranties by such Holder as reasonably deemed necessary by Company to effect compliance by the Company with the requirements of applicable federal and/or state securities laws.

7.3         Transfer .  Subject to Section 7.2, the Warrants shall be transferable only on the Warrant Register upon delivery thereof duly endorsed by the Holder or by his duly authorized attorney or representative, or accompanied by proper evidence of succession, assignment or authority to transfer, which endorsement shall be guaranteed by a  financial institution that is a participant in a recognized signature guarantee program.  In all cases of transfer by an attorney, the original power of attorney, duly approved, or a copy thereof, duly certified, shall be deposited and remain with the Company (or the warrant agent, if appointed).  In case of transfer by executors, administrators, guardians or other legal representatives, duly authenticated evidence of their authority shall be produced, and may be required to be deposited and remain with the Company (or the warrant agent, if appointed) in its discretion.  Upon any registration of transfer, the Company shall execute and deliver (or if appointed, the warrant agent shall countersign and deliver) a new Warrant or Warrants to the persons entitled thereto.

Section 8.            Exchange of Warrant Certificates .  Each Warrant certificate may be exchanged, at the option of the Holder thereof, for another Warrant certificate or Warrant certificates in different denominations entitling the Holder or Holders thereof to purchase a like aggregate number of Warrant Shares as the certificate or certificates surrendered then entitle each Holder to purchase.  Any Holder desiring to exchange a Warrant certificate or certificates shall make such request in writing delivered to the Company at its principal office (or, if a warrant agent is appointed, the warrant agent at its principal office) and shall surrender, properly endorsed, the certificate or

certificates to be so exchanged.  Thereupon, the Company (or, if appointed, the warrant agent) shall execute and deliver to the person entitled thereto a new Warrant certificate or certificates, as the case may be, as so requested, in such name or names as such Holder shall designate.

Section 9.            Mutilated or Missing Warrants .  In case any of the certificates evidencing the Warrants shall be mutilated, lost, stolen or destroyed, the Company may in its discretion issue and deliver (and, if appointed, the warrant agent shall countersign and deliver) in exchange and substitution for and upon cancellation of the mutilated Warrant certificate, or in lieu of and substitution for the Warrant certificate lost, stolen or destroyed, a new Warrant certificate of like tenor, but only upon receipt of evidence reasonably satisfactory to the Company and the warrant agent (if so appointed) of such loss, theft or destruction of such Warrant and an indemnity or bond, if requested, also reasonably satisfactory to them.  An applicant for such a substitute Warrant certificate shall also comply with such other reasonable regulations and pay such other reasonable charges as the Company (or the warrant agent, if so appointed) may prescribe.

Section 10.         Adjustment of Warrant Price and Number of Warrant Shares .  The number and kind of securities purchasable upon the exercise of each Warrant and the Warrant Price shall be subject to adjustment from time to time upon the happening of certain events, as hereinafter defined.

10.1      Adjustments .  The number of Warrant Shares purchasable upon the exercise of each Warrant and the Warrant Price shall be subject to adjustment as follows:

(a)           In the event that the Company shall (i) pay a dividend in shares of Common Stock or make a distribution in shares of Common Stock, (ii) subdivide its outstanding shares of Common Stock, (iii) combine its outstanding shares of Common Stock into a smaller number of shares of Common Stock or (iv) reclassify or change (including a change to the right to receive, or a change into, as the case may be (other than with respect to a merger or consolidation pursuant to the exercise of appraisal rights), shares of stock, other securities, property, cash or any combination thereof) its Common Stock (including any such reclassification or change in connection with a consolidation or merger in which the Company is the surviving corporation), the number of Warrant Shares purchasable upon exercise of each Warrant immediately prior thereto shall be adjusted so that the Holder of each Warrant shall be entitled to receive the kind and number of Warrant Shares or other securities of the Company or other property which he would have owned or have been entitled to receive after the happening of any of the events described above, had such Warrant been exercised immediately prior to the happening of such event or any record date with respect thereto.  An adjustment made pursuant to this paragraph (a) shall become effective immediately after the effective date of such event retroactive to the record date, if any, for such event.

(b)           In case the Company shall issue rights, options or warrants to all holders of its outstanding Common Stock, without any charge to such holders, entitling them to subscribe for or purchase shares of Common Stock at a price per share which is lower at the record date mentioned below than the then current market price per share of Common Stock (as defined in paragraph (d) below), the number of Warrant Shares thereafter purchasable upon the exercise of each

Warrant shall be determined by multiplying the number of Warrant Shares theretofore purchasable upon exercise of each Warrant by a fraction, of which the numerator shall be the number of shares of Common Stock outstanding on the date of issuance of such rights, options or warrants plus the number of additional shares of Common Stock offered for subscription or purchase in connection with such rights, options or warrants, and of which the denominator shall be the number of shares of Common Stock outstanding on the date of issuance of such rights, options or warrants plus the number of shares which the aggregate offering price of the total number of shares of Common Stock so offered would purchase at the current market price per share of Common Stock at such record date.  Such adjustment shall be made whenever such rights, options or warrants are issued, and shall become effective immediately after the record date for the determination of stockholders entitled to receive such rights, options or warrants.

(c)           In case the Company shall distribute to all holders of its shares of Common Stock, (including any distribution made in connection with a merger in which the Company is the surviving corporation), evidences of its indebtedness or assets (excluding cash, dividends or distributions payable out of consolidated earnings or earned surplus and dividends or distributions referred to in paragraph (a) above) or rights, options or warrants, or convertible or exchangeable securities containing the right to subscribe for or purchase shares of Common Stock (excluding those referred to in paragraph (b) above), then in each case the number of Warrant Shares thereafter purchasable upon the exercise of each Warrant shall be determined by multiplying the number of Warrant Shares theretofore