1





THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), OR UNDER THE SECURITIES LAW OF ANY STATE.
THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE AND
MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE ACT AND THE
APPLICABLE STATE SECURITIES LAWS, PURSUANT TO REGISTRATION OR EXEMPTION
THEREFROM.  THE ISSUER OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL
(WHICH MAY BE COMPANY COUNSEL) IN FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER
TO THE EFFECT THAT ANY PROPOSED TRANSFER OR RESALE IS IN COMPLIANCE WITH THE
ACT AND ANY APPLICABLE STATE SECURITIES LAWS.



                                  WARRANT TO PURCHASE STOCK         WARRANT NO. WE-3
                                                                                ----
                       
Corporation:              BIOSTAR, INC. a Delaware corporation

Number of Shares:         85,714

Class of Stock:           Series E Preferred

Initial Exercise Price:   $1.75 per share

Issue Date:               September 15, 1995

Expiration Date:          September 14, 2001


         THIS WARRANT CERTIFIES THAT, for the agreed upon value of $100.00,
SILICON VALLEY BANK ("HOLDER") is entitled to purchase the number of fully paid
and nonassessable shares of the class of securities (the "SHARES") of the
corporation (the "COMPANY") at the initial exercise price per Share (the
"WARRANT PRICE") all as set forth above and as adjusted pursuant to Article 2
of this Warrant, subject to the provisions and upon the terms and conditions
set forth of this Warrant.

                                   ARTICLE 1



                                   EXERCISE.

     1.1         METHOD OF EXERCISE.  Holder may exercise this Warrant by
delivering a duly executed Notice of Exercise in substantially the form
attached as Appendix 1 to the principal office of the Company.  Unless Holder
is exercising the conversion right set forth in Section 1.2, Holder shall also
deliver to the Company a check for the aggregate Warrant Price for the Shares
being purchased.

     1.2         CONVERSION RIGHT.  In lieu of exercising this Warrant as
specified in Section 1.1, Holder may from time to time convert this Warrant, in
whole or in part, into a number of Shares determined by dividing (a) the
aggregate fair market value of the Shares or other securities otherwise
issuable upon exercise of this Warrant minus the aggregate Warrant Price of
such Shares by (b) the fair market value of one Share.  The fair market value
of the Shares shall be determined pursuant Section 1.4.

     1.3         [INTENTIONALLY DELETED]
   2
     1.4         FAIR MARKET VALUE.  If the Shares are traded in a public
market, the fair market value of the Shares shall be the closing price of the
Shares (or the closing price of the Company's stock into which the Shares are
convertible) reported for the business day immediately before Holder delivers
its Notice of Exercise to the Company.  If the Shares are not traded in a
public market, the Board of Directors of the Company shall determine fair
market value in its reasonable good faith judgment.  The foregoing
notwithstanding, if Holder advises the Board of Directors in writing that
Holder disagrees with such determination, then the Company and Holder shall
promptly agree upon a reputable investment banking firm to undertake such
valuation.  If the valuation of such investment banking firm is greater than
that determined by the Board of Directors, then all fees and expenses of such
investment banking firm shall be paid by the Company.  In all other
circumstances, such fees and expenses shall be paid by Holder.

     1.5         DELIVERY OF CERTIFICATE AND NEW WARRANT.  Promptly after
Holder exercises or converts this Warrant, the Company shall deliver to Holder
certificates for the Shares acquired and, if this Warrant has not been fully
exercised or converted and has not expired, a new Warrant representing the
Shares not so acquired.

     1.6         REPLACEMENT OF WARRANTS.  On receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and, in the case of loss, theft or destruction, on delivery of an
indemnity agreement reasonably satisfactory in form and amount to the Company
or, in the case of mutilation, or surrender and cancellation of this Warrant,
the Company at its expense shall execute and deliver, in lieu of this Warrant,
a new warrant of like tenor.

     1.7         REPURCHASE ON SALE, MERGER, OR CONSOLIDATION OF THE COMPANY.

          1.7.1  "ACQUISITION".  For the purpose of this Warrant, "ACQUISITION"
means any sale, license, or other disposition of all or substantially all of
the assets of the Company, or any reorganization, consolidation, or merger of
the Company where the holders of the Company's securities before the
transaction beneficially own less than 50% of the outstanding voting securities
of the surviving entity after the transaction.

          1.7.2  ASSUMPTION OF WARRANT.  Upon the closing of any Acquisition,
this Warrant shall be exercisable for the same securities, cash, and property
as would be payable for the Shares issuable upon exercise of the unexercised
portion of this Warrant as if such Shares were outstanding on the record date
for the Acquisition and subsequent closing.  The Warrant Price shall be
adjusted accordingly.

          1.7.3  [INTENTIONALLY DELETED]

                                   ARTICLE 2

                           ADJUSTMENTS TO THE SHARES.

     2.1         STOCK DIVIDENDS, SPLITS, ETC.  If the Company declares or pays
a dividend on its common stock (or the Shares if the Shares are securities
other than common stock) payable in common stock, or other securities,
subdivides the outstanding common stock into a greater amount of common stock,
or, if the Shares are securities other than common stock, subdivides





                                       2.
   3
the Shares in a transaction that increases the amount of common stock into
which the Shares are convertible, then upon exercise of this Warrant, for each
Share acquired, Holder shall receive, without cost to Holder, the total number
and kind of securities to which Holder would have been entitled had Holder
owned the Shares of record as of the date the dividend or subdivision occurred.

     2.2         RECLASSIFICATION, EXCHANGE OR SUBSTITUTION.  Upon any
reclassification, exchange, substitution, or other event that results in a
change of the number and/or class of the securities issuable upon exercise or
conversion of this Warrant, Holder shall be entitled to receive, upon exercise
or conversion of this Warrant, the number and kind of securities and property
that Holder would have received for the Shares if this Warrant had been
exercised immediately before such reclassification, exchange, substitution, or
other event.  Such an event shall include any automatic conversion of the
outstanding or issuable securities of the Company of the same class or series
as the Shares to common stock pursuant to the terms of the Company's Articles
of Incorporation upon the closing of a registered public offering of the
Company's common stock.  The Company or its successor shall promptly issue to
Holder a new Warrant for such new securities or other property.  The new
Warrant shall provide for adjustments which shall be as nearly equivalent as
may be practicable to the adjustments provided for in this Article 2 including,
without limitation, adjustments to the Warrant Price and to the number of
securities or property issuable upon exercise of the new Warrant.  The
provisions of this Section 2.2 shall similarly apply to successive
reclassifications, exchanges, substitutions, or other events.

     2.3         ADJUSTMENTS FOR COMBINATIONS, ETC.  If the outstanding Shares
are combined or consolidated, by reclassification or otherwise, into a lesser
number of shares, the Warrant Price shall be proportionately increased.

     2.4         ADJUSTMENTS FOR DILUTING ISSUANCES.  The Warrant Price and the
number of Shares issuable upon exercise of this Warrant or, if the Shares are
Preferred Stock, the number of shares of common stock issuable upon conversion
of the Shares, shall be subject to adjustment, from time to time in the manner
set forth on Exhibit A in the event of Diluting Issuances (as defined on
Exhibit A).

     2.5         NO IMPAIRMENT.  The Company shall not, by amendment of its
Articles of Incorporation or through a reorganization, transfer of assets,
consolidation, merger, dissolution, issue, or sale of securities or any other
voluntary action, avoid or seek to avoid the observance or performance of any
of the terms to be observed or performed under this Warrant by the Company, but
shall at all times in good faith assist in carrying out of all the provisions
of this Article 2 and in taking all such action as may be necessary or
appropriate to protect Holder's rights under this Article against impairment.
If the Company takes any action affecting the Shares or its common stock other
than as described above that adversely affects Holder's rights under this
Warrant, the Warrant Price shall be adjusted downward and the number of Shares
issuable upon exercise of this Warrant shall be adjusted upward in such a
manner that the aggregate Warrant Price of this Warrant is unchanged.

     2.6         FRACTIONAL SHARES.  No fractional Shares shall be issuable
upon exercise or conversion of the Warrant and the number of Shares to be
issued shall be rounded down to the





                                       3.
   4
nearest whole Share.  If a fractional share interest arises upon any exercise
or conversion of the Warrant, the Company shall eliminate such fractional share
interest by paying Holder amount computed by multiplying the fractional
interest by the fair market value of a full Share.

     2.7         CERTIFICATE AS TO ADJUSTMENT.  Holder shall be entitled to the
same rights with respect to notices regarding adjustments as provided to the
holders of Series E Preferred Stock as set forth in the Company's Restated
Certificate of Incorporation.

     2.8         NO RIGHTS AS SHAREHOLDERS.  This Warrant does not entitled
Holder to any voting rights or other rights as a stockholder of the Company
prior to the exercise of the Holder's rights to purchase Preferred Stock as
provided for herein.

                                   ARTICLE 3

                 REPRESENTATIONS AND COVENANTS OF THE COMPANY.

     3.1         REPRESENTATIONS AND WARRANTIES.  The Company hereby represents
and warrants to the Holder as follows:

               (a)        The initial Warrant Price referenced on the first
page of this Warrant is not greater than (i) the price per share at which the
Shares were last issued in an arms-length transaction in which at least
$500,000 of the Shares were sold and (ii) the fair market value of the Shares
as of the date of this Warrant.

               (b)        All Shares which may be issued upon the exercise of
the purchase right represented by this Warrant, and all securities, if any,
issuable upon conversion of the Shares, shall, upon issuance, be duly
authorized, validly issued, fully paid and nonassessable, and free of any liens
and encumbrances except for restrictions on transfer provided for herein or
under applicable federal and state securities laws.

     3.2         NOTICE OF CERTAIN EVENTS.  If the Company proposes at any time
(a) to declare any dividend or distribution upon its common stock, whether in
cash, property, stock, or other securities and whether or not a regular cash
dividend; (b) to offer for subscription pro rata to the holders of any class or
series of its stock any additional shares of stock of any class or series or
other rights; (c) to effect any reclassification or recapitalization of common
stock; (d) to merge or consolidate with or into any other corporation, or sell,
lease, license, or convey all or substantially all of its assets, or to
liquidate, dissolve or wind up; or (e) offer holders of registration rights the
opportunity to participate in an underwritten public offering of the company's
securities for cash, then, in connection with each such event, the Company
shall give Holder (1) at least 20 days prior written notice of the date on
which a record will be taken for such dividend, distribution, or subscription
rights (and specifying the date on which the holders of common stock will be
entitled thereto) or for determining rights to vote, if any, in respect of the
matters referred to in (c) and (d) above; (2) in the case of the matters
referred to in (c) and (d) above at least 20 days prior written notice of the
date when the same will take place (and specifying the date on which the
holders of common stock will be entitled to exchange their common stock for
securities or other property deliverable upon the occurrence of such event);





                                       4.
   5
and (3) in the case of the matter referred to in (e) above, the same notice as
is given to the holders of such registration rights.

     3.3         INFORMATION RIGHTS.  So long as the Holder holds this Warrant
and/or any of the Shares, the Company shall deliver to the Holder promptly
after mailing, copies of all notices or other written communications to the
shareholders of the Company.

     3.4         REGISTRATION UNDER SECURITIES ACT OF 1933, AS AMENDED.  The
Company agrees that the Shares or, if the Shares are convertible into common
stock of the Company, such common stock, shall be subject to the registration
rights set forth on Exhibit B, if attached.

                                   ARTICLE 4

                    REPRESENTATIONS AND COVENANTS OF HOLDER.

         This Warrant has been entered into by the Company in reliance upon the
following representations and covenants of Holder, which by its acceptance
hereof the Holder hereby confirms:

     4.1         INVESTMENT PURPOSE.  The right to acquire Preferred Stock or
the Preferred Stock issuable upon exercise of Holder's rights contained herein
will be acquired for investment and not with a view to the sale or distribution
of any part thereof, and the Holder has no present intention of selling or
engaging in any public distribution of the same except pursuant to a
registration or exemption.

     4.2         PRIVATE ISSUE.  Holder understands (i) that the Preferred
Stock issuable upon exercise of the Warrantholder's rights contained herein is
not registered under the 1933 Act or qualified under applicable state
securities law on the ground that the issuance contemplated by this Warrant
Agreement will be exempt from the registration and qualifications requirements
thereof, and (ii) that the Company's reliance on such exemption is predicated
on the representations set forth in this Section 4.

     4.3         FINANCIAL RISK.  Holder has such knowledge and experience in
financial and business matters as to be capable of evaluating the merits and
risks of its investment and has the ability to bear the economic risks of its
investment.

     4.4         RISK OF NO REGISTRATION.  Holder understands that if the
Company does not register with the Securities and Exchange Commission pursuant
to Section 12 of the 1933 Act, or file reports pursuant to Section 15(d) of the
Securities Exchange Act of 1934 (the "1934 ACT"), or if a registration
statement covering the securities under the 1933 Act is not in effect when it
desires to sell (i) the rights to purchase Preferred Stock pursuant to this
Warrant Agreement, or (ii) the Preferred Stock issuable upon exercise of the
right to purchase, it may be required to hold such securities for an indefinite
period.  The Holder also understands that any sale of the rights of the Holder
to purchase Preferred Stock which might be made by it in reliance upon Rule 144
under the 1933 Act may be made only in accordance with the terms and conditions
of that Rule.

     4.5         ACCREDITED INVESTOR.  Holder is an "ACCREDITED INVESTOR"
within the meaning of Rule 501 of Regulation D under the Act, as presently in
effect.





                                       5.
   6
                                   ARTICLE 5

                                 MISCELLANEOUS.

     5.1         TERM; NOTICE OF EXPIRATION.  This Warrant is exercisable, in
whole or in part, at any time and from time to time on or before the Expiration
Date set forth above or, if sooner, the date that is three years after the date
that the Company sells its shares in a registered public offering under the
Securities Act of 1933, as amended.

     5.2         LEGENDS.  This Warrant and the Shares (and the securities
issuable, directly or indirectly, upon conversion of the Shares, if any) shall
be imprinted with a legend in substantially the following form:

         THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
         SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR UNDER THE
         SECURITIES LAW OF ANY STATE.  THESE SECURITIES ARE SUBJECT TO
         RESTRICTIONS ON TRANSFERABILITY AND RESALE AND MAY NOT BE TRANSFERRED
         OR RESOLD EXCEPT AS PERMITTED UNDER THE ACT AND THE APPLICABLE STATE
         SECURITIES LAWS, PURSUANT TO REGISTRATION OR EXEMPTION THEREFROM.  THE
         ISSUER OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL (WHICH
         MAY BE COMPANY COUNSEL) IN FORM AND SUBSTANCE SATISFACTORY TO THE
         ISSUER TO THE EFFECT THAT ANY PROPOSED TRANSFER OR RESALE IS IN
         COMPLIANCE WITH THE ACT AND ANY APPLICABLE STATE SECURITIES LAWS.

     5.3         COMPLIANCE WITH SECURITIES LAWS ON TRANSFER.  This Warrant and
the Shares issuable upon exercise this Warrant (and the securities issuable,
directly or indirectly, upon conversion of the Shares, if any) may not be
transferred or assigned in whole or in part without compliance with applicable
federal and state securities laws by the transferor and the transferee
(including, without limitation, the delivery of investment representation
letters and legal opinions reasonably satisfactory to the Company, as
reasonably requested by the Company).  The Company shall not require Holder to
provide an opinion of counsel if the transfer is to an affiliate of Holder,
provided such affiliate makes the representations and warranties as are
included in Article 4 above, or if there is no material question as to the
availability of current information as referenced in Rule 144 (c), Holder
represents that it has complied with Rule 144(d) and (e) in reasonable detail,
the selling broker represents that it has complied with Rule 144(f), and the
Company is provided with a copy of Holder's notice of proposed sale.

     5.4         TRANSFER PROCEDURE.  Subject to the provisions of Section 4.2,
Holder may transfer all or part of this Warrant or the Shares issuable upon
exercise of this Warrant (or the securities issuable, directly or indirectly,
upon conversion of the Shares, if any) by giving the Company notice of the
portion of the Warrant being transferred setting forth the name, address and
taxpayer identification number of the transferee and surrendering this Warrant
to the Company for reissuance to the transferee(s) (and Holder if applicable).
Unless the Company is filing financial information with the SEC pursuant to the
Securities Exchange Act of 1934, the





                                       6.
   7
Company shall have the right to refuse to transfer any portion of this Warrant
to any person who directly competes with the Company.

     5.5         NOTICES.  All notices and other communications from the
Company to the Holder, or vice versa, shall be deemed delivered and effective
when given personally or mailed by first-class registered or certified mail,
postage prepaid, at such address as may have been furnished to the Company or
the Holder, as the case may be, in writing by the Company or such holder from
time to time.

     5.6         WAIVER.  This Warrant and any term hereof may be changed,
waived, discharged or terminated only by an instrument in writing signed by the
party against which enforcement of such change, waiver; discharge or
termination is sought.

     5.7         ATTORNEYS FEES.  In the event of any dispute between the
parties concerning the terms and provisions of this Warrant, the party
prevailing in such dispute shall be entitled to collect from the other party
all costs incurred in such dispute, including reasonable attorneys' fees.

     5.8         GOVERNING LAW.  This Warrant shall be governed by and
construed in accordance with the laws of the State of California, without
giving effect to its principles regarding conflicts of law.

                             
                              COMPANY:
                             
                              BIOSTAR, INC.
                             
                              By:    /s/ Teresa W. Ayers                    
                                   -----------------------------------------
                             
                              Name:    Teresa W. Ayers                   
                                     ------------------------------------
                             
                                                    (Print)
                             
                             Title:  Vice President
                             
                              By:    /s/ Teresa W. Ayers                    
                                   -----------------------------------------
                             
                              Name:    Teresa W. Ayers                   
                                     ------------------------------------
                             
                                                    (Print)
                             
                              Title:  Chief Financial Officer, Secretary





                                       7.
   8
                                   APPENDIX 1

                               NOTICE OF EXERCISE

     1.  The undersigned hereby elects to purchase __________ shares of the
Common/Series __________ Preferred [STRIKE ONE] Stock of __________________
pursuant to the terms of the attached Warrant, and tenders herewith payment of
the purchase price of such shares in full.

     1.  The undersigned hereby elects to convert the attached Warrant into
Shares in the manner specified in the Warrant.  This conversion is exercised
with respect to ______________ of the Shares covered by the Warrant.

     [STRIKE PARAGRAPH THAT DOES NOT APPLY.]

     2.  Please issue a certificate or certificates representing said shares in
the name of the undersigned or in such other name as is specified below:


                              ------------------------
                                   (Name)

                              ------------------------

                              ------------------------
                                   (Address)

     3.  The undersigned represents it is acquiring the shares solely for its
own account and not as a nominee for any other party and not with a view toward
the resale or distribution thereof except in compliance with applicable
securities laws.

                              ---------------------------------------
                              (Signature)

- ------------------
(Date)





                                       1.
   9
                                   EXHIBIT A

                            ANTI-DILUTION PROVISIONS
                  (FOR PREFERRED STOCK WARRANTS WITH EXISTING
                           ANTI-DILUTION PROTECTION)

     In the event of the issuance (a "DILUTING ISSUANCE") by the Company, after
the Issue Date of the Warrant, of securities at a price per share less than the
Warrant Price, then the number of shares of common stock issuable upon
conversion of the Shares shall be adjusted in accordance with those provisions
(the "PROVISIONS") of the Company's Articles (Certificate) of Incorporation
which apply to Diluting Issuances.

     Under no circumstances shall the aggregate Warrant Price payable by the
Holder upon exercise of the Warrant increase as a result of any adjustment
arising from a Diluting Issuance.





                                       1.
   10
                                   EXHIBIT B

                              REGISTRATION RIGHTS

     The Shares (if common stock), or the common stock issuable upon conversion
of the Shares, shall be deemed "REGISTRABLE SECURITIES" or otherwise entitled
to "PIGGY BACK" registration rights in accordance with the terms of the
following agreement (the "AGREEMENT") between the Company and its investor(s):

          Amended and Restated Investor Rights Agreement, dated as of
                           November 14, 1994 between
              the Company and certain shareholders of the Company     

     The Company agrees that no amendments will be made to the Agreement which
would have an adverse impact on Holder's registration rights thereunder without
the consent of Holder.  By acceptance of the Warrant to which this Exhibit B is
attached, Holder shall be deemed to be a party to the Agreement.

     If no Agreement exists, then the Company and the Holder shall enter into
Holder's standard form of Registration Rights Agreement as in effect on the
Issue Date of the Warrant.





                                       1.