QuickLinks -- Click here to rapidly navigate through this document

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549


FORM 8-A

FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
PURSUANT TO SECTION 12(b) OR (g) OF THE
SECURITIES EXCHANGE ACT OF 1934


MACROPORE BIOSURGERY, INC.
(Exact name of registrant as specified in its charter)

Delaware   33-0827593
(State or other jurisdiction of incorporation)   (I.R.S. Employer Identification No.)

6740 Top Gun Street
San Diego, California 92121
(Address of principal executive offices and zip code)

Securities to be registered pursuant to Section 12(b) of the Act:

Title of each class
to be so registered

  Name of each exchange on which
each class is to be registered

Not applicable    

Securities to be registered pursuant to Section 12(g) of the Act:

Preferred Share Purchase Rights
Pursuant to Rights Agreement
(Title of Class)




Item 1.    Description of Securities to be Registered.     

        On May 28, 2003, the Board of Directors (the "Board") of MacroPore Biosurgery, Inc. (the "Corporation") declared a dividend distribution of one preferred share purchase right (a "Right") for each outstanding share of Common Stock, par value $0.001 (the "Common Stock"), of the Corporation. The dividend is payable to the stockholders of record on June 10, 2003 (the "Record Date") with respect to shares of Common Stock issued thereafter until the Distribution Date (as defined below) and, in certain circumstances, with respect to shares of Common Stock issued after the Distribution Date. Except as set forth below, each Right, when it becomes exercisable, entitles the registered holder to purchase from the Corporation one one-thousandth (1/1000th) of a share of Series RP Preferred Stock of the Corporation, $0.001 par value per share (the "Preferred Stock"), at a price of $25.00 per one one-thousandth (1/1000th) of a share of Preferred Stock (the "Purchase Price"), subject to adjustment. The description and terms of the Rights are set forth in a Rights Agreement (the "Rights Agreement") between the Corporation and Computershare Trust Company, Inc., as Rights Agent (the "Rights Agent"), dated as of May 29, 2003.

        Initially, the Rights will be attached to certificates representing shares of Common Stock then outstanding, and no separate certificates representing the Rights ("Right Certificates") will be distributed. The Rights will separate from the Common Stock upon the earlier to occur of (i) a person or group of affiliated or associated persons having acquired, without the prior approval of the Board, beneficial ownership of 15% or more of the outstanding shares of Common Stock or (ii) 10 days, or such later date as the Board may determine, following the commencement of or announcement of an intention to make, a tender offer or exchange offer the consummation of which would result in a person or group of affiliated or associated persons becoming an Acquiring Person (as hereinafter defined) except pursuant to a Permitted Offer (as hereinafter defined) (the "Distribution Date"). A person or group whose acquisitions of shares of Common Stock cause a Distribution Date pursuant to clause (i) above is an "Acquiring Person," with certain exceptions as set forth in the Rights Agreement. The date that a person or group is first publicly announced to have become such by the Corporation or such Acquiring Person is the "Shares Acquisition Date."

        The Rights Agreement provides that, until the Distribution Date, the Rights will be transferred with and only with the associated shares of Common Stock. Until the Distribution Date (or earlier redemption or expiration of the Rights), new Common Stock certificates issued after the Record Date upon transfer or new issuance of shares of Common Stock will contain a notation incorporating the Rights Agreement by reference. Until the Distribution Date (or earlier redemption or expiration of the Rights), the surrender for transfer of any certificates for shares of Common Stock outstanding as of the Record Date, even without attaching thereto such notation or a copy of the Summary of Rights attached to the Rights Agreement as Exhibit C, will also constitute the transfer of the Rights associated with the shares of Common Stock represented by such certificate. As soon as practicable following the Distribution Date, Right Certificates will be mailed to the holders of record of shares of the Common Stock as of the Close of Business (as defined in the Rights Agreement) on the Distribution Date (and to each initial record holder of certain shares of Common Stock issued after the Distribution Date), and such separate Right Certificates alone will evidence the Rights.

        The Rights are not exercisable until the Distribution Date and will expire at the close of business on May 29, 2013, unless earlier redeemed by the Corporation as described below.

        In the event that any person becomes an Acquiring Person (except pursuant to a tender or exchange offer which is for all outstanding shares of Common Stock at a price and on terms which a majority of certain members of the Board determines to be adequate and in the best interests of the Corporation, its stockholders and other relevant constituencies, other than such Acquiring Person, its affiliates and associates (a "Permitted Offer")), each holder of a Right will thereafter have the right (the "Flip-In Right") to receive upon exercise the number of shares of Common Stock (or, in certain

2



circumstances, of one one-thousandths (1/1000ths) of a share of Preferred Stock or other securities of the Corporation) having a value (immediately prior to such triggering event) equal to two times the then-applicable Purchase Price of the Right. Notwithstanding the foregoing, following the occurrence of the event described above, all Rights that are, or (under certain circumstances specified in the Rights Agreement) were, beneficially owned by any Acquiring Person or any affiliate or associate thereof will be null and void. The Board has the option, at any time after any person becomes an Acquiring Person, to exchange all or part of the then-exercisable Rights (excluding those that have become void, as described in the immediately preceding sentence) for shares of Common Stock, at an exchange ratio determined by dividing the then-applicable Purchase Price by the then-current market price per share of Common Stock as determined in accordance with the Rights Agreement. However, this option generally terminates if any person becomes the beneficial owner of 50% or more of the Common Stock.

        In the event that, at any time following the Shares Acquisition Date, (i) the Corporation is acquired in a merger or other business combination transaction in which the holders of all of the outstanding shares of Common Stock immediately prior to the consummation of the transaction are not the holders of all of the surviving corporation's voting power, or (ii) more than 50% of the Corporation's assets or earning power is sold or transferred, in either case with or to (x) an Acquiring Person or any affiliate or associate thereof or (y) any other person in which such Acquiring Person, affiliate or associate has an interest or any person acting on behalf of or in concert with such Acquiring Person, affiliate or associate, or (z) if, in such transaction, all holders of shares of Common Stock are not treated alike, any other person, then each holder of a Right (except Rights which previously have been voided as set forth above) shall thereafter have the right (the "Flip-Over Right") to receive, upon exercise, common shares of the acquiring company (or, in certain circumstances, its parent) having a value equal to two times the exercise price of the Right. The holder of a Right will continue to have the Flip-Over Right whether or not such holder exercises or surrenders the Flip-In Right.

        The Purchase Price payable, and the number of shares of Preferred Stock, shares of Common Stock or other securities issuable, upon exercise of the Rights are subject to adjustment from time to time to prevent dilution (i) in the event of a stock dividend on, or a subdivision, combination or reclassification of, the Preferred Stock, (ii) upon the grant to holders of shares of the Preferred Stock of certain rights or warrants to subscribe for or purchase shares of Preferred Stock at a price, or securities convertible into Preferred Stock with a conversion price, less than the then current market price of the Preferred Stock or (iii) upon the distribution to holders of shares of the Preferred Stock of evidences of indebtedness or assets (excluding regular quarterly cash dividends) or of subscription rights or warrants (other than those referred to above).

        The number of outstanding Rights and the number of one one-thousandths (1/1000ths) of a share of Preferred Stock issuable upon exercise of each Right are also subject to adjustment in the event of a stock split of the Common Stock or a stock dividend on the Common Stock payable in Common Stock or subdivisions, consolidations or combinations of the Common Stock occurring, in any such case, prior to the Distribution Date.

        With certain exceptions, no adjustment in the Purchase Price will be required until cumulative adjustments require an adjustment of at least 1% in such Purchase Price.

        At any time prior to the earlier to occur of (i) a person becoming an Acquiring Person or (ii) the expiration of the Rights, and under certain other circumstances, the Corporation may redeem the Rights in whole, but not in part, at a price (payable in cash or, at the Corporation's election, in Common Stock) of $0.001 per Right (the "Redemption Price"), which redemption shall be effective upon the action of the Board. Additionally, following the Shares Acquisition Date, the Corporation may redeem the then outstanding Rights in whole, but not in part, at the Redemption Price, provided that such redemption is in connection with a merger or other business combination transaction or

3



series of transactions involving the Corporation in which all holders of shares of Common Stock are treated alike but not involving an Acquiring Person or its affiliates or associates.

        Other than those provisions relating to the rights, duties and obligations of the Rights Agent and certain principal economic terms of the Rights, all of the provisions of the Rights Agreement may be amended by the Board prior to the Distribution Date. After the Distribution Date, the provisions of the Rights Agreement may be amended by the Board in order to cure any ambiguity, defect or inconsistency, to make changes that do not adversely affect the interests of holders of Rights (excluding the interests of any Acquiring Person), or, subject to certain limitations, to shorten or lengthen any time period under the Rights Agreement.

        Until a Right is exercised, the holder thereof, as such, will have no rights as a stockholder of the Corporation, including, without limitation, the right to vote or to receive dividends. While the distribution of the Rights will not be taxable to stockholders of the Corporation, stockholders may, depending upon the circumstances, recognize taxable income should the Rights become exercisable or upon the occurrence of certain events thereafter.

        This summary description of the Rights does not purport to be complete and is qualified in its entirety by reference to the Rights Agreement, which is hereby incorporated herein by reference.

        As of May 28, 2003, there were 14,546,099 shares of Common Stock outstanding. Each share of Common Stock outstanding on the Record Date will receive one Right. As long as the Rights are attached to the shares of Common Stock, the Corporation will issue one Right with each new share of Common Stock so that all such shares will have attached rights.

        The Rights have certain anti-takeover effects. The Rights will cause substantial dilution to a person or group that attempts to acquire the Corporation without conditioning the offer on the Rights being redeemed or a substantial number of Rights being acquired. However, the Rights should not interfere with any tender offer or merger approved by the Corporation (other than with an Acquiring Person) because the Rights do not become exercisable in the event of a Permitted Offer or other acquisition exempted by the Board.

        Attached hereto as Exhibit 4.1 and incorporated herein by reference are copies of the Rights Agreement and the exhibits thereto, as follows: Exhibit A—Form of Certificate of Designation, Preferences and Rights of Series RP Preferred Stock of MacroPore Biosurgery, Inc.; Exhibit B—Form of Right Certificate; and Exhibit C—Summary of Rights to Purchase Series RP Preferred Stock. The foregoing description of the Rights is qualified in its entirety by reference to the Rights Agreement and such exhibits thereto.

Item 2.    Exhibits.     


[REST OF PAGE INTENTIONALLY LEFT BLANK]

4



SIGNATURE

        Pursuant to the requirements of Section 12 of the Securities Exchange Act of 1934, the registrant has duly caused this registration statement to be signed on its behalf by the undersigned, thereto duly authorized.

    MACROPORE BIOSURGERY, INC.

 

 

By:

 

/s/  
CHRISTOPHER J. CALHOUN      
    Name:   Christopher J. Calhoun
    Title:   President / Chief Executive Officer

Date: May 29, 2003

5




EXHIBIT INDEX

Exhibit
  Description
4.1   Rights Agreement, dated as of May 29, 2003, between MacroPore Biosurgery, Inc. and Computershare Trust Company, Inc. as Rights Agent, which includes: as Exhibit A thereto, the Form of Certificate of Designation, Preferences and Rights of Series RP Preferred Stock of MacroPore Biosurgery, Inc.; as Exhibit B thereto, the Form of Right Certificate; and, as Exhibit C thereto, the Summary of Rights to Purchase Series RP Preferred Stock.



QuickLinks

SIGNATURE
EXHIBIT INDEX

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 4.1



MACROPORE BIOSURGERY, INC.

and

COMPUTERSHARE TRUST COMPANY, INC., AS RIGHTS AGENT

RIGHTS AGREEMENT

DATED AS OF MAY 29, 2003



TABLE OF CONTENTS

1.   Certain Definitions.   1

2.

 

Appointment of Rights Agent.

 

4

3.

 

Issuance of Right Certificates.

 

5

4.

 

Form of Right Certificate.

 

6

5.

 

Countersignature and Registration.

 

7

6.

 

Transfer, Split-Up, Combination and Exchange of Right Certificates; Mutilated, Destroyed, Lost or Stolen Right Certificates.

 

7

7.

 

Exercise of Rights; Purchase Price; Expiration Date of Rights.

 

8

8.

 

Cancellation and Destruction of Right Certificates.

 

10

9.

 

Reservation and Availability of Preferred Stock.

 

10

10.

 

Preferred Stock Record Date.

 

11

11.

 

Adjustment of Purchase Price, Number and Kind of Shares or Number of Rights.

 

11

12.

 

Certificate of Adjusted Purchase Price or Number of Shares.

 

17

13.

 

Consolidation, Merger or Sale or Transfer of Assets or Earning Power.

 

17

14.

 

Fractional Rights and Fractional Shares.

 

19

15.

 

Rights of Action.

 

20

16.

 

Agreement of Right Holders.

 

21

17.

 

Right Certificate Holder Not Deemed a Stockholder.

 

21

18.

 

Concerning the Rights Agent.

 

22

19.

 

Merger or Consolidation or Change of Name of Rights Agent.

 

22

20.

 

Duties of Rights Agent.

 

23

21.

 

Change of Rights Agent.

 

25

22.

 

Issuance of New Right Certificates.

 

25

23.

 

Redemption and Termination.

 

26

24.

 

Notice of Certain Events.

 

27

25.

 

Miscellaneous.

 

28

26.

 

Exchange.

 

29

Exhibit A—Form of Certificate of Designation, Preferences and Rights of Series RP Preferred Stock

 

A-1

Exhibit B—Form of Right Certificate

 

B-1

Exhibit C—Form of Summary of Rights

 

C-1

i


RIGHTS AGREEMENT

        This RIGHTS AGREEMENT (the "Agreement") is made effective as of 5:00 p.m. San Diego time on the 29th day of May, 2003 by and between MacroPore Biosurgery, Inc., a Delaware corporation (the "Corporation"), and Computershare Trust Company, Inc., a Colorado corporation (the "Rights Agent"), with respect to the following facts and circumstances.

        A.    The Board of Directors of the Corporation (the "Board") has authorized and declared a dividend of one preferred share purchase right (a "Right") for each share of Common Stock (as hereinafter defined) of the Corporation outstanding at the Close of Business (as hereinafter defined) on June 10, 2003 (the "Record Date"), each Right representing the right to purchase one one-thousandth (1/1000th) of a share of Preferred Stock (as hereinafter defined), upon the terms and subject to the conditions herein set forth.

        B.    The Board of Directors of the Corporation has further authorized and directed the issuance of one Right with respect to each share of Common Stock that shall become outstanding between the Record Date and the earliest of the Distribution Date, the Redemption Date or the Final Expiration Date (as such terms are hereinafter defined); provided, however, that Rights may be issued with respect to shares of Common Stock that shall become outstanding after the Distribution Date and prior to the earlier of the Redemption Date and the Final Expiration Date in accordance with the provisions of Section 22 of this Agreement.

        NOW, THEREFORE, in consideration of the foregoing and the mutual agreements herein set forth, the parties hereby agree as follows:

        1.    Certain Definitions.    

        For purposes of this Agreement, the following terms have the meanings indicated:


2


3


        2.    Appointment of Rights Agent.    

4


        3.    Issuance of Right Certificates.    

5


        4.    Form of Right Certificate.    

6


        5.    Countersignature and Registration.    

        6.    Transfer, Split-Up, Combination and Exchange of Right Certificates; Mutilated, Destroyed, Lost or Stolen Right Certificates.    

7


        7.    Exercise of Rights; Purchase Price; Expiration Date of Rights.    

8


9


        8.    Cancellation and Destruction of Right Certificates.    

        All Right Certificates surrendered for the purpose of exercise, transfer, split up, combination or exchange shall, if surrendered to the Corporation or to any of its agents, be delivered to the Rights Agent for cancellation or in cancelled form, or, if surrendered to the Rights Agent, shall be cancelled by it, and no Right Certificates shall be issued in lieu thereof except as expressly permitted by the provisions of this Rights Agreement. The Corporation shall deliver to the Rights Agent for cancellation and retirement, and the Rights Agent shall so cancel and retire, any other Right Certificate purchased or acquired by the Corporation otherwise than upon the exercise thereof. The Rights Agent shall deliver all cancelled Right Certificates to the Corporation, or shall, at the written request of the Corporation, destroy such cancelled Right Certificates, and in such case shall deliver a certificate of destruction thereof to the Corporation.

        9.    Reservation and Availability of Preferred Stock.    

10


        10.    Preferred Stock Record Date.    

        Each Person in whose name any certificate for shares of Preferred Stock (or shares of Common Stock and/or other securities, as the case may be) is issued upon the exercise of Rights shall for all purposes be deemed to have become the holder of record of the shares of Preferred Stock (or shares of Common Stock and/or other securities, as the case may be) represented thereby on, and such certificate shall be dated, the date upon which the Right Certificate evidencing such Rights was duly surrendered and payment of the Purchase Price (and any applicable taxes and governmental charges) was made; provided, however, that, if the date of such surrender and payment is a date upon which the shares of Preferred Stock (or shares of Common Stock and/or other securities, as the case may be) transfer books of the Corporation are closed, such person shall be deemed to have become the record holder of such shares on, and such certificate shall be dated, the next succeeding Business Day on which the shares of Preferred Stock (or shares of Common Stock and/or other securities, as the case may be) transfer books of the Corporation are open.

        11.    Adjustment of Purchase Price, Number and Kind of Shares or Number of Rights.    

        The Purchase Price, the number and kind of shares covered by each Right and the number of Rights outstanding are subject to adjustment from time to time as provided in this Section 11.

11


12


13


14


15


16


        12.    Certificate of Adjusted Purchase Price or Number of Shares.    

        Whenever an adjustment is made as provided in Section 11 or Section 13 hereof, the Corporation shall promptly (a) prepare a certificate setting forth such adjustment and a brief, reasonably detailed statement of the facts, computations and methodology accounting for such adjustment, (b) file with the Rights Agent and with each transfer agent for the Common Stock and the Preferred Stock a copy of such certificate and (c) mail a brief summary thereof to each holder of a Right Certificate in accordance with Section 25.1 hereof. The Rights Agent shall be fully protected in relying on any such certificate and on any adjustment therein contained and shall have no duty with respect to, and shall not be deemed to have knowledge of, such adjustment unless and until it shall have received such certificate.

        13.    Consolidation, Merger or Sale or Transfer of Assets or Earning Power.    

17


18


        14.    Fractional Rights and Fractional Shares.    

19


        15.    Rights of Action.    

        All rights of action in respect of this Agreement, excepting the rights of action given to the Rights Agent under Section 18 hereof, are vested in the respective registered holders of the Right Certificates (and, prior to the Distribution Date, the registered holders of shares of the Common Stock); and any registered holder of any Right Certificate (or, prior to the Distribution Date, of shares of the Common Stock), without the consent of the Rights Agent or of the holder of any other Right Certificate (or, prior to the Distribution Date, of shares of the Common Stock), may, in such registered holder's own behalf and for such registered holder's own benefit, enforce, and may institute and maintain any suit, action or proceeding against the Corporation to enforce, or otherwise act in respect of, such registered holder's right to exercise the Rights evidenced by such Right Certificate in the manner provided in

20



such Right Certificate and in this Agreement. Without limiting the foregoing or any remedies available to the holders of Rights, it is specifically acknowledged that the holders of Rights would not have an adequate remedy at law for any breach of this Agreement and will be entitled to specific performance of the obligations under, and injunctive relief against actual or threatened violations of the obligations of any Person subject to, this Agreement. Nothing in this Section 15 is intended to modify or limit the authority of the Board of Directors under Section 25.3.

        16.    Agreement of Right Holders.    

        Every holder of a Right, by accepting the same, consents and agrees with the Corporation and the Rights Agent and with every other holder of a Right that:

        17.    Right Certificate Holder Not Deemed a Stockholder.    

        No holder, as such, of any Right Certificate shall be entitled to vote, receive dividends or be deemed for any purpose the holder of shares of the Preferred Stock or any other securities of the Corporation that may at any time be issuable on the exercise of the Rights represented thereby, nor shall anything contained herein or in any Right Certificate be construed to confer upon the holder of any Right Certificate, as such, any of the rights of a stockholder of the Corporation or any right to vote for the election of directors or upon any matter submitted to stockholders at any meeting thereof, or to give or withhold consent to any corporate action, or to receive notice of meetings or other actions affecting stockholders (except as provided in Section 24 hereof), or to receive dividends or other distributions or to exercise any preemptive or subscription rights, or otherwise, until the Right or Rights evidenced by such Right Certificate shall have been exercised in accordance with the provisions hereof.

21



        18.    Concerning the Rights Agent.    

        19.    Merger or Consolidation or Change of Name of Rights Agent.    

22


        20.    Duties of Rights Agent.    

23


24


        21.    Change of Rights Agent.    

        The Rights Agent or any successor Rights Agent may resign and be discharged from its duties under this Agreement upon thirty (30) days' notice in writing mailed to the Corporation and to each transfer agent of the Common Stock or Preferred Stock by registered or certified mail, and, at the expense of the Corporation, to the holders of the Right Certificates by first-class mail. The Corporation may remove the Rights Agent or any successor Rights Agent upon sixty (60) days' notice in writing, mailed to the Rights Agent or successor Rights Agent, as the case may be, and to each transfer agent of the Common Stock or Preferred Stock by registered or certified mail, and to holders of the Right Certificates by first-class mail. If the Rights Agent shall resign or be removed or shall otherwise become incapable of acting, the Corporation shall appoint a successor to the Rights Agent. If the Corporation shall fail to make such appointment within a period of sixty (60) days after giving notice of such removal or after it has been notified in writing of such resignation or incapacity by the resigning or incapacitated Rights Agent or by the holder of a Right Certificate (who shall, with such notice, submit his Right Certificate for inspection by the Corporation), then the registered holder of any Right Certificate may apply to any court of competent jurisdiction for the appointment of a new Rights Agent. Any successor Rights Agent, whether appointed by the Corporation or by such a court, shall be (i) a Person organized and doing business under the laws of the United States or of any of the States of New York, New Jersey, Colorado or California (or of any other state of the United States so long as such Person is authorized to do business in any of the States of New York, New Jersey, Colorado or California), in good standing, having an office in any of such States, which is subject to supervision or examination by federal or state authority and which (or the parent corporation of which) has at the time of its appointment as Rights Agent a combined capital and surplus of at least $50,000,000 or (ii) an affiliate of such Person. After appointment, the successor Rights Agent shall be vested with the same powers, rights, duties and responsibilities as if it had been originally named as Rights Agent without further act or deed; but the predecessor Rights Agent shall deliver and transfer to the successor Rights Agent any property at the time held by it hereunder, and execute and deliver any further assurance, conveyance, act or deed necessary for the purpose. In case at the time such successor Rights Agent shall succeed to the agency created by this Agreement, any of the Right Certificates shall have been countersigned but not delivered, any such successor Rights Agent may adopt the countersignature of a predecessor Rights Agent and deliver such Right Certificates so countersigned; and in case at that time any of the Right Certificates shall not have been countersigned, any successor Rights Agent may countersign such Right Certificates either in the name of the predecessor or in the name of the successor Rights Agent; and in all such cases such Right Certificates shall have the full force provided in the Right Certificates and in this Agreement. Not later than the effective date of any such appointment, the Corporation shall file notice thereof in writing with the predecessor Rights Agent and each transfer agent of the Common Stock or Preferred Stock, and mail a notice thereof in writing to the registered holders of the Right Certificates. Failure to give any notice provided for in this Section 21, however, or any defect therein, shall not affect the legality or validity of the resignation or removal of the Rights Agent or the appointment of the successor Rights Agent, as the case may be.

        22.    Issuance of New Right Certificates.    

25


        23.    Redemption and Termination.    

26


        24.    Notice of Certain Events.    

27


        25.    Miscellaneous.    

28


        26.    Exchange.    

29


[REST OF PAGE INTENTIONALLY LEFT BLANK]

30


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

    MACROPORE BIOSURGERY, INC.
Attest:        

 

 

By:

 

/s/  
CHRISTOPHER J. CALHOUN      
    Name:   Christopher J. Calhoun
    Title:   President, Chief Executive Officer

 

 

COMPUTERSHARE TRUST COMPANY, INC.,
    as Rights Agent

 

 

By:

 

/s/  
THERESA HENSHAW      
    Name:   Theresa Henshaw
    Title:   Trust Officer / OPS Manager

 

 

COMPUTERSHARE TRUST COMPANY, INC.

 

 

By:

 

/s/  
K. GWINN      
    Name:   K. Gwinn
    Title:   V.P.

Exhibit A

Certificate of Designation, Preferences and
Rights of Series RP Preferred Stock

of

MacroPore Biosurgery, Inc.

(Pursuant to § 151 of the Delaware General Corporation Law)

        I, Jonathan E. Soneff, Secretary of MacroPore Biosurgery, Inc. (the "Corporation"), a corporation organized and existing under the General Corporation Law of the State of Delaware, in accordance with the provisions of Section 103 thereof, DO HEREBY CERTIFY:

        That pursuant to the authority conferred upon the Board of Directors of the Corporation by the Restated Certificate of Incorporation of the Corporation, the said Board of Directors on May 28, 2003, adopted the following resolutions creating a series of 9,500 shares of Preferred Stock designated as Series RP Preferred Stock.

        RESOLVED, that pursuant to the authority granted to and vested in the Board of Directors of the Corporation in accordance with the provisions of the Restated Certificate of Incorporation of the Corporation, the Board of Directors hereby creates a series of Series RP Preferred Stock, with a par value of $0.001 per share, of the Corporation and hereby states the designation and number of shares, and fixes the relative rights, preferences and limitations thereof as follows (the following provisions being intended to operate in addition to any other provisions of said Restated Certificate of Incorporation applicable to any series of Preferred Stock):

Series RP Preferred Stock

        Section 1.    Designation, Par Value and Amount.    The shares of such series shall be designated as "Series RP Preferred Stock" (hereinafter referred to as "Series RP Preferred Stock"), the shares of such series shall be with par value of $0.001 per share, and the number of shares constituting such series shall be 9,500; provided, however, that, if more than a total of 9,500 shares of Series RP Preferred Stock shall be issuable upon the exercise of Rights (the "Rights") issued pursuant to the Rights Agreement, dated as of May 29, 2003, between the Corporation and Computershare Trust Company, Inc., as Rights Agent (as amended from time to time, the "Rights Agreement"), the Board of Directors of the Corporation shall direct by resolution or resolutions that a certificate be properly executed, acknowledged and filed providing for the total number of shares of Series RP Preferred Stock authorized to be issued to be increased (to the extent that the Restated Certificate of Incorporation then permits) to the largest number of whole shares (rounded up to the nearest whole number) issuable upon exercise of the Rights.

        Section 2.    Dividends and Distributions.    

A-1


        Section 3.    Voting Rights.    The holders of shares of Series RP Preferred Stock shall have the following voting rights:

A-2


        Section 4.    Certain Restrictions.    

A-3


        Section 5.    Reacquired Shares.    Any shares of Series RP Preferred Stock purchased or otherwise acquired by the Corporation in any manner whatsoever shall be retired and cancelled promptly after the acquisition thereof. All such shares shall upon their cancellation become authorized but unissued shares of Preferred Stock and may be reissued as part of a new series of Preferred Stock subject to the conditions and restrictions on issuance set forth herein, in the Certificate of Incorporation, in any other Certificate of Amendment creating a series of Preferred Stock or as otherwise required by law.

        Section 6.    Liquidation, Dissolution or Winding Up.    

A-4


        Section 7.    Consolidation, Merger, etc.    In case the Corporation shall enter into any consolidation, merger, combination or other transaction in which the shares of Common Stock are exchanged for or changed into other stock or securities, cash and/or any other property, then in any such case the shares of Series RP Preferred Stock shall at the same time be similarly exchanged or changed in an amount per share equal to the Adjustment Number (as appropriately adjusted as set forth in Section 6.3 to reflect such events as stock splits, stock dividends and recapitalizations with respect to the Common Stock) times the aggregate amount of stock, securities, cash and/or any other property (payable in kind), as the case may be, into which or for which each share of Common Stock is changed or exchanged.

        Section 8.    No Redemption.    The shares of Series RP Preferred Stock shall not be redeemable.

        Section 9.    Ranking.    The Series RP Preferred Stock shall rank junior to all other series of the Corporation's Preferred Stock as to the payment of dividends and the distribution of assets, unless the terms of any such other series shall provide otherwise.

        Section 10.    Amendment.    The Restated Certificate of Incorporation of the Corporation shall not be further amended in any manner that would materially alter or change the powers, preferences or special rights of the Series RP Preferred Stock so as to affect them adversely without the affirmative vote of the holders of a majority or more of the outstanding shares of Series RP Preferred Stock, voting separately as a class.

        Section 11.    Fractional Shares.    Series RP Preferred Stock may be issued in fractions of a share which shall entitle the holder, in proportion to such holder's fractional shares, to exercise voting rights, receive dividends, participate in distributions and have the benefit of all other rights of holders of Series RP Preferred Stock.

A-5


        RESOLVED, that the proper officers of the Corporation be, and each of them hereby is, authorized to execute a Certificate of Designation with respect to the Series RP Preferred Stock pursuant to Section 151 of the General Corporation Law of the State of Delaware and to take all appropriate action to cause such Certificate to become effective, including, but not limited to, the filing and recording of such Certificate with and/or by the Secretary of State of the State of Delaware.

[REST OF PAGE INTENTIONALLY LEFT BLANK]

A-6


        IN WITNESS WHEREOF, I have executed and subscribed to this Certificate and do affirm the foregoing as true under penalty of perjury this 29th day of May, 2003.

    By:   /s/  JONATHAN E. SONEFF      
    Name:   Jonathan E. Soneff
    Title:   Secretary

A-7


Exhibit B

Form of Right Certificate

Certificate No. RP-       
  Rights

Right Certificate

MACROPORE BIOSURGERY, INC.

        This certifies that                        , or registered assigns, is the registered owner of the number of Rights set forth above, each of which entitles the owner thereof, subject to the terms, provisions and conditions of the Rights Agreement, dated as of May 29, 2003 (the "Rights Agreement"), between MacroPore Biosurgery, Inc., a Delaware corporation (the "Corporation"), and Computershare Trust Company, Inc., a Colorado corporation, (the "Rights Agent") to purchase from the Corporation at any time after the Distribution Date (as such term is defined in the Rights Agreement) and prior to 5:00 P.M., California time, on May 29, 2013, unless the Rights evidenced hereby shall have been previously redeemed by the Corporation, at the principal office or offices of the Rights Agent designated for such purpose, or at the office of its successor as Rights Agent, one one-thousandth (1/1000th) of a fully paid non-assessable share of Series RP Preferred Stock (the "Preferred Stock") of the Corporation, at a purchase price of $25.00 per one one-thousandth (1/1000th) of a share of Preferred Stock (the "Purchase Price"), upon presentation and surrender of this Right Certificate with the Form of Election to Purchase duly executed. The number of Rights evidenced by this Right Certificate (and the number of one one-thousandths (1/1000ths) of a share of Preferred Stock that may be purchased upon exercise hereof) set forth above, and the Purchase Price set forth above, are the number and Purchase Price as of June 10, 2003, based on the Preferred Stock as constituted at such date.

        Upon the occurrence of a Section 11.1.2 Event (as such term is defined in the Rights Agreement), if the Rights evidenced by this Right Certificate are beneficially owned by (i) an Acquiring Person or an Affiliate or Associate of an Acquiring Person, (ii) a transferee of an Acquiring Person (or of any Affiliate or Associate thereof) who becomes a transferee after the Acquiring Person becomes such, or (iii) a transferee of an Acquiring Person (or of an Affiliate or Associate thereof) who becomes a transferee prior to or concurrently with the Acquiring Person becoming such and receives such Rights pursuant to either (A) a transfer (whether or not for consideration) from the Acquiring Person (or from any Affiliate or Associate thereof) to holders of equity interests in such Acquiring Person or to any Person with whom the Acquiring Person has a continuing agreement, arrangement or understanding regarding the transferred Rights or (B) a transfer that the Board of Directors of the Corporation has determined is part of a plan, arrangement or understanding that has as a primary purpose or effect the avoidance of Section 7.6 of the Rights Agreement, shall become null and void without any further action and no holder hereof shall have any rights whatsoever with respect to such Rights, whether under any provision of the Rights Agreement or otherwise.

        As provided in the Rights Agreement, the Purchase Price and the number of one one-thousandths (1/1000ths) of a share of Preferred Stock or other securities that may be purchased upon the exercise of the Rights evidenced by this Right Certificate are subject to modification and adjustment upon the happening of certain events, including Triggering Events (as such term is defined in the Rights Agreement).

B-1



        This Right Certificate is subject to all of the terms, covenants and restrictions of the Rights Agreement, which terms, covenants and restrictions are hereby incorporated herein by reference and made a part hereof and to which Rights Agreement reference is hereby made for a full description of the rights, limitations of rights, obligations, duties and immunities hereunder of the Rights Agent, the Corporation and the holders of the Right Certificates, which limitations of rights include the temporary suspension of the exercisability of such Rights under the specific circumstances set forth in the Rights Agreement. Copies of the Rights Agreement are on file at the principal executive offices of the Corporation and the office of the Rights Agent.

        This Right Certificate, with or without other Right Certificates, upon surrender at the designated office of the Rights Agent, may be exchanged for another Right Certificate or Right Certificates of like tenor and date evidencing Rights entitling the holder to purchase a like aggregate number of shares of Preferred Stock or other securities as the Rights evidenced by the Right Certificate or Right Certificates surrendered shall have entitled such holder to purchase. If this Right Certificate shall be exercised in part, the holder shall be entitled to receive upon surrender hereof another Right Certificate or Right Certificates for the number of whole Rights not exercised.

        Subject to the provisions of the Rights Agreement, the Rights evidenced by this Certificate may be redeemed by the Corporation at a redemption price of $0.001 per Right (subject to adjustment as provided in the Rights Agreement) payable in cash.

        No fractional shares of Preferred Stock will be issued upon the exercise of any Right or Rights evidenced hereby (other than fractions that are one one-thousandth (1/1000th) or integral multiples of one one-thousandth (1/1000th) of a share of Preferred Stock, which may, at the election of the Corporation, be evidenced by depository receipts), but in lieu thereof a cash payment will be made, as provided in the Rights Agreement.

        No holder of this Right Certificate shall be entitled to vote or receive dividends or be deemed for any purpose the holder of shares of the Preferred Stock or of any other securities of the Corporation that may at any time be issuable on the exercise hereof, nor shall anything contained in the Rights Agreement or herein be construed to confer upon the holder hereof, as such, any of the rights of a stockholder of the Corporation or any right to vote for the election of directors or upon any matter submitted to stockholders at any meeting thereof, or to give or withhold consent to any corporate action, or to receive notice of meetings or other actions affecting stockholders (except as provided in the Rights Agreement), or to receive dividends or other distributions or to exercise any preemptive or subscription rights, or otherwise, until the Right or Rights evidenced by this Right Certificate shall have been exercised as provided in the Rights Agreement.

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

B-2



        WITNESS the facsimile signature of the proper officers of the Corporation and its corporate seal. Dated as of                        ,             .

[SEAL]
ATTEST:
  MACROPORE BIOSURGERY, INC.

By

 

    


 

By

 

    


Name

 

    


 

Name

 

    


Title

 

    


 

Title

 

    


Countersigned:

 

 

 

 

COMPUTERSHARE TRUST COMPANY, INC.

By

 

    


 

 

 

 

Name

 

    


 

 

 

 

Title

 

    


 

 

 

 

B-3


Form of Reverse Side of Right Certificate

FORM OF ASSIGNMENT

        FOR VALUE RECEIVED                                                 hereby sells, assigns and transfers unto

    
(Please print name and address of transferee)
    
this Right Certificate, together with all right, title and interest therein, and does hereby irrevocably constitute and appoint                        Attorney-in-Fact, to transfer the within Right Certificate on the books of the within-named Corporation, with full power of substitution.

Dated:

 

                        ,            

 

 
   
 
Signature

 

 

 

 

 
Signature Guaranteed:    

    


 

 

        Signatures must be guaranteed by an "Eligible Guarantor Institution" as defined in Rule 17Ad-15 (or any successor rule or regulation) promulgated pursuant to the Securities Exchange Act of 1934, as amended (this term means, in general, banks, stock brokers, savings and loan associations, and credit unions, in each case with membership in an approved signature guarantee medallion program).

        The undersigned hereby certifies that (1) the Rights evidenced by this Right Certificate are not being sold, assigned or transferred by or on behalf of a Person who is or was an Acquiring Person or an Affiliate or Associate thereof (as such terms are defined in the Rights Agreement), (2) this Right Certificate is not being sold, assigned or transferred to or on behalf of any such Acquiring Person, Affiliate or Associate, and (3) after due inquiry and to the best knowledge of the undersigned, the undersigned did not acquire the Rights evidenced by this Right Certificate from any Person who is or was an Acquiring Person or an Affiliate or Associate thereof (as such terms are defined in the Rights Agreement).

        
Signature

Form of Reverse Side of Right Certificate—continued

FORM OF ELECTION TO PURCHASE

To the Rights Agent:

        The undersigned hereby irrevocably elects to exercise                        Rights represented by this Right Certificate to purchase the shares of Preferred Stock, shares of Common Stock or other securities issuable upon the exercise of such Rights and requests that certificates for such shares of Preferred Stock, shares of Common Stock or other securities be issued in the name of:

Please insert social security number
or other identifying number       
    
(Please print name and address)

        If such number of Rights shall not be all the Rights evidenced by this Right Certificate, a new Right Certificate for the balance remaining of such Rights shall be registered in the name of and delivered to:

Please insert social security number
or other identifying number       
    
(Please print name and address)

Dated:

 

                        ,            

 

 
   
 
Signature

 

 

 

 

 
Signature Guaranteed:    

    


 

 

        Signatures must be guaranteed by an "Eligible Guarantor Institution" as defined in Rule 17Ad-15 (or any successor rule or regulation) promulgated pursuant to the Securities Exchange Act of 1934, as amended (this term means, in general, banks, stock brokers, savings and loan associations, and credit unions, in each case with membership in an approved signature guarantee medallion program).


Form of Reverse Side of Right Certificate—continued

        The undersigned hereby certifies that (1) the Rights evidenced by this Right Certificate are not being exercised by or on behalf of a Person who is or was an Acquiring Person or an Affiliate or Associate thereof (as such terms are defined in the Rights Agreement), (2) this Right Certificate is not being sold, assigned or transferred by or on behalf of any such Acquiring Person, Affiliate or Associate, and (3) after due inquiry and to the best knowledge of the undersigned, the undersigned did not acquire the Rights evidenced by this Right Certificate from any Person who is or was an Acquiring Person or an Affiliate or Associate thereof (as such terms are defined in the Rights Agreement).

        
Signature

 

 

Notice

        The signature on the foregoing Forms of Assignment and Election and certificates must conform to the name as written upon the face of this Right Certificate in every particular, without alteration or enlargement or any change whatsoever.

        In the event the certification set forth above in the Form of Assignment or the Form of Election to Purchase, as the case may be, is not completed, the Corporation and the Rights Agent will deem the Beneficial Owner of the Rights evidenced by this Right Certificate to be an Acquiring Person or an Affiliate or Associate thereof (as such terms are defined in the Right Agreement) and such Assignment or Election to Purchase will not be honored.



Exhibit C

MACROPORE BIOSURGERY, INC.
6740 Top Gun Street
San Diego, California 92121

SUMMARY OF RIGHTS TO PURCHASE
SERIES RP PREFERRED SHARES

        On May 28, 2003, the Board of Directors (the "Board") of MacroPore Biosurgery, Inc. (the "Corporation") declared a dividend distribution of one preferred share purchase right (a "Right") for each outstanding share of Common Stock (the "Common Stock") of the Corporation. The dividend is payable to the stockholders of record on June 10, 2003 (the "Record Date"), and with respect to shares of Common Stock issued thereafter until the Distribution Date (as defined below) and, in certain circumstances, with respect to shares of Common Stock issued after the Distribution Date. Except as set forth below, each Right, when it becomes exercisable, entitles the registered holder to purchase from the Corporation one one-thousandth (1/1000th) of a share of Series RP Preferred Stock, $0.001 par value per share (the "Preferred Stock"), of the Corporation at a price of $25.00 per one one-thousandth (1/1000th) of a share of Preferred Stock (the "Purchase Price"), subject to adjustment. The description and terms of the Rights are set forth in a Rights Agreement (the "Rights Agreement") between the Corporation and Computershare Trust Company, Inc., as Rights Agent (the "Rights Agent"), dated as of May 29, 2003.

        Initially, the Rights will be attached to all certificates representing shares of Common Stock then outstanding, and no separate certificates representing the Rights ("Right Certificates") will be distributed. The Rights will separate from the Common Stock upon the earliest to occur of (i) a person or group of affiliated or associated persons having acquired, without the prior approval of the Corporation's Board of Directors, beneficial ownership of 15% or more of the outstanding shares of Common Stock (except pursuant to a Permitted Offer, as hereinafter defined) or (ii) 10 days (or such later date as the Board may determine) following the commencement of, or announcement of an intention to make, a tender offer or exchange offer the consummation of which would result in a person or group of affiliated or associated persons becoming an Acquiring Person (as hereinafter defined) (the "Distribution Date"). A person or group whose acquisitions of shares of Common Stock cause a Distribution Date pursuant to clause (i) above is an "Acquiring Person," with certain exceptions as set forth in the Rights Agreement. The date that a person or group is first publicly announced to have become such by the Corporation or such Acquiring Person is the "Shares Acquisition Date."

        The Rights Agreement provides that, until the Distribution Date, the Rights will be transferred with and only with the associated shares of Common Stock. Until the Distribution Date (or earlier redemption or expiration of the Rights), new Common Stock certificates issued after the Record Date upon transfer or new issuance of shares of Common Stock will contain a notation incorporating the Rights Agreement by reference. Until the Distribution Date (or earlier redemption or expiration of the Rights), the surrender for transfer of any certificates for shares of Common Stock outstanding as of the Record Date, even without such notation or a copy of this

        Summary of Rights being attached thereto, will also constitute the transfer of the Rights associated with the shares of Common Stock represented by such certificate. As soon as practicable following the Distribution Date, Right Certificates will be mailed to the holders of record of the shares of Common Stock as of the Close of Business (as defined in the Rights Agreement) on the Distribution Date (and to each initial record holder of certain shares of Common Stock issued after the Distribution Date), and such separate Right Certificates alone will evidence the Rights.

        The Rights are not exercisable until the Distribution Date and will expire at the close of business on May 29, 2013, unless earlier redeemed by the Corporation as described below.

C-1



        In the event that any person becomes an Acquiring Person (except pursuant to a tender or exchange offer which is for all outstanding shares of Common Stock at a price and on terms which a majority of certain members of the Board determines to be adequate and in the best interests of the Corporation, its stockholders and other relevant constituencies, other than such Acquiring Person, its affiliates and associates (a "Permitted Offer")), each holder of a Right will thereafter have the right (the "Flip-In Right") to receive, upon exercise, the number of shares of Common Stock (or, in certain circumstances, of one one-thousandths (1/1000ths) of a share of Preferred Stock or other securities of the Corporation) having a value (immediately prior to such triggering event) equal to two times the exercise price of the Right. Notwithstanding the foregoing, following the occurrence of the event described above, all Rights that are, or (under certain circumstances specified in the Rights Agreement) were, beneficially owned by any Acquiring Person or any affiliate or associate thereof will be null and void. The Board has the option, at any time after any person becomes an Acquiring Person, to exchange all or part of the then-exercisable Rights (excluding those that have become void, as described in the immediately preceding sentence) for shares of Common Stock, at an exchange ratio determined by dividing the then-applicable Purchase Price by the then-current market price per share of Common Stock as determined in accordance with the Rights Agreement. However, this option generally terminates if any person becomes the beneficial owner of 50% or more of the Common Stock.

        In the event that, at any time following the Shares Acquisition Date, (i) the Corporation is acquired in a merger or other business combination transaction in which the holders of all of the outstanding shares of Common Stock immediately prior to the consummation of the transaction are not the holders of all of the surviving corporation's voting power, or (ii) more than 50% of the Corporation's assets or earning power is sold or transferred, in either case with or to (x) an Acquiring Person or any affiliate or associate thereof or (y) any other person in which such Acquiring Person, affiliate or associate has an interest or any person acting on behalf of or in concert with such Acquiring Person, affiliate or associate, or (z) if, in such transaction, all holders of shares of Common Stock are not treated alike, any other person, then each holder of a Right (except Rights which previously have been voided as set forth above) shall thereafter have the right (the "Flip-Over Right") to receive, upon exercise, common shares of the acquiring company (or, in certain circumstances, its parent), having a value equal to two times the exercise price of the Right. The holder of a Right will continue to have the Flip-Over Right whether or not such holder exercises or surrenders the Flip-In Right. The Purchase Price payable, and the number of shares of Preferred Stock, shares of Common Stock or other securities issuable, upon exercise of the Rights are subject to adjustment from time to time to prevent dilution (i) in the event of a stock dividend on, or a subdivision, combination or reclassification of, the Preferred Stock, (ii) upon the grant to holders of shares of the Preferred Stock of certain rights or warrants to subscribe for or purchase Preferred Stock at a price, or securities convertible into Preferred Stock with a conversion price, less than the then current market price of the Preferred Stock or (iii) upon the distribution to holders of shares of the Preferred Stock of evidences of indebtedness or assets (excluding regular quarterly cash dividends) or of subscription rights or warrants (other than those referred to above).

        The number of outstanding Rights and the number of one one-thousandths (1/1000ths) of a share of Preferred Stock issuable upon exercise of each Right are also subject to adjustment in the event of a stock split of the Common Stock or a stock dividend on the Common Stock payable in Common Stock or subdivisions, consolidations or combinations of the Common Stock occurring, in any such case, prior to the Distribution Date.

        Preferred Stock purchasable upon exercise of the Rights will not be redeemable. Each share of Preferred Stock will be entitled to a minimum preferential quarterly dividend payment of $1.00 per share but, if greater, will be entitled to an aggregate dividend per share of 1,000 times the dividend declared per share of Common Stock. In the event of liquidation, the holders of shares of the

C-2



Preferred Stock will be entitled to a minimum preferential liquidation payment per share in an amount equal to the greater of $25.00 or 1,000 times the payment made per share of Common Stock plus an amount equal to accrued and unpaid dividends and distributions thereon, whether or not declared, to the date of such payment (the "Series RP Liquidation Preference"); thereafter, and after the holders of shares of the Common Stock receive a liquidation payment of an amount equal to the quotient obtained by dividing the Series RP Liquidation Preference by 1,000 (subject to certain adjustments for stock splits, stock dividends and recapitalizations with respect to the Common Stock), the holders of shares of the Preferred Stock and the holders of the Common Stock will share the remaining assets in the ratio of 1,000 to 1 (as adjusted) for each share of Preferred Stock and Common Stock so held, respectively. Finally, in the event of any merger, consolidation or other transaction in which shares of Common Stock are exchanged, each share of Preferred Stock will be entitled to receive 1,000 times the amount received per share of Common Stock. These rights are protected by customary antidilution provisions. In the event that the amount of accrued and unpaid dividends on the Preferred Stock is equivalent to six full quarterly dividends or more, the holders of shares of the Preferred Stock shall have the right, voting as a class, to elect two directors in addition to the directors elected by the holders of shares of the Common Stock until all cumulative dividends on the Preferred Stock have been paid or set apart for payment through the last quarterly dividend payment date. No fractional shares of Preferred Stock will be issued (other than fractions which are one one-thousandth (1/1000th) or integral multiples of one one-thousandth (1/1000th) of a share of Preferred Stock, which may, at the election of the Corporation, be evidenced by depositary receipts) and in lieu thereof, an adjustment in cash will be made based on the market price of the Preferred Stock on the last trading day prior to the date of exercise. With certain exceptions, no adjustment in the Purchase Price will be required until cumulative adjustments require an adjustment of at least 1% in such Purchase Price.

        At any time prior to the earlier to occur of (i) a person becoming an Acquiring Person or (ii) the expiration of the Rights, and under certain other circumstances, the Corporation may redeem the Rights in whole, but not in part, at a price (payable in cash or, at the Corporation's election, in Common Stock) of $0.001 per Right (the "Redemption Price"), which redemption shall be effective upon the action of the Board. Additionally, following the Shares Acquisition Date, the Corporation may redeem the then outstanding Rights in whole, but not in part, at the Redemption Price, provided that such redemption is in connection with a merger or other business combination transaction or series of transactions involving the Corporation in which all holders of shares of Common Stock are treated alike but not involving an Acquiring Person or its affiliates or associates.

        Other than those provisions relating to the rights, duties and obligations of the Rights Agent and certain principal economic terms of the Rights, all of the provisions of the Rights Agreement may be amended by the Board of Directors of the Corporation prior to the Distribution Date. After the Distribution Date, the provisions of the Rights Agreement may be amended by the Board of Directors of the Corporation in order to cure any ambiguity, defect or inconsistency, to make changes that do not adversely affect the interests of holders of Rights (excluding the interests of any Acquiring Person), or, subject to certain limitations, to shorten or lengthen any time period under the Rights Agreement.

        Until a Right is exercised, the holder thereof, as such, will have no rights as a stockholder of the Corporation, including, without limitation, the right to vote or to receive dividends. While the distribution of the Rights will not be taxable to stockholders of the Corporation, stockholders may, depending upon the circumstances, recognize taxable income should the Rights become exercisable or upon the occurrence of certain events thereafter.

        A copy of the Rights Agreement has been filed with the Securities and Exchange Commission as an Exhibit to a Registration Statement on Form 8-A. A copy of the Rights Agreement is available free of charge from the Corporation. This summary description of the Rights does not purport to be complete and is qualified in its entirety by reference to the Rights Agreement, which is hereby incorporated herein by reference.

C-3





QuickLinks

MACROPORE BIOSURGERY, INC. and COMPUTERSHARE TRUST COMPANY, INC., AS RIGHTS AGENT RIGHTS AGREEMENT DATED AS OF MAY 29, 2003