STOCK PURCHASE COMMITMENT AGREEMENT
                          (Series F Preferred Stock)


                                    between

                           AASTROM BIOSCIENCES, INC.


                                      and


                            COBE LABORATORIES, INC.



                               October 29, 1996
<PAGE>
 
                               TABLE OF CONTENTS
                               -----------------

                                                                            Page
                                                                            ----

1.  Definitions..............................................................  1

2.  Commitment to Purchase Shares............................................  3

3.  Closing..................................................................  3

4.  Representations and Warranties of the Purchaser..........................  4

5.  Representations and Warranties of the Company............................  6
     5.1.   Organization, Qualifications and Corporate Power.................  6
     5.2.   Authorization of Agreement.......................................  7
     5.3.   Validity.........................................................  7
     5.4.   Authorized Capital Stock.........................................  8
     5.5.   Litigation.......................................................  8
     5.6.   Financial Statements.............................................  9
     5.7.   No Convictions...................................................  9
     5.8.   Brokers..........................................................  9
     5.9.   Subsidiaries.....................................................  9
     5.10.  Directors and Officers...........................................  9
     5.11.  No Material Adverse Change....................................... 10
     5.12.  Taxes............................................................ 10
     5.13.  Employee Benefit Plans........................................... 10
     5.14.  Title to Properties.............................................. 11
     5.15.  Leasehold Interests.............................................. 11
     5.16.  Insurance........................................................ 11
     5.17.  Other Agreements................................................. 11
     5.18.  Patents, Trademarks, Etc......................................... 12
     5.19.  Proprietary Information of Third Parties......................... 12
     5.20.  Compliance With Law.............................................. 13
     5.21.  Loans and Advances............................................... 14
     5.22.  Assumptions, Guaranties, Etc. of Indebtedness of Other Persons... 14
     5.23.  Governmental Approvals........................................... 14
     5.24.  Disclosure....................................................... 14
     5.25.  Offering of Shares............................................... 15
     5.26.  Transactions With Affiliates..................................... 15

6.  Covenants of the Company................................................. 15
     6.1.   Ordinary Course of Business...................................... 15

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<PAGE>
 
      6.2.   Updated Information............................................  15
      6.3.   Board of Directors Seat........................................  15

7.   Stock Registration Rights..............................................  15

9.   Information Rights.....................................................  16

10.  Company's Put Right....................................................  16

11.  Purchaser's Preemptive Rights..........................................  16

13.  General Provisions.....................................................  16
      13.1.  Irrevocability; Binding Effect.................................  16
      13.2.  Modification...................................................  17
      13.3.  Notices........................................................  17
      13.4.  Assignability..................................................  17
      13.5.  Applicable Law.................................................  17
      13.6.  Confidentiality................................................  17
      13.7.  Entirety.......................................................  17
      13.8.  Survival.......................................................  18
      13.9.  Expenses.......................................................  18
      13.10. Construction...................................................  18
      13.11. Severability...................................................  18
      13.12. Counterparts...................................................  19
 

EXHIBITS:

 A        Amended and Restated Articles of Incorporation

 B        Opinion of Legal Counsel to the Company



SCHEDULES:

 5.5      Litigation

 6.4      Stock Schedule

                                      ii
<PAGE>
 
                      STOCK PURCHASE COMMITMENT AGREEMENT
                          (Series F Preferred Stock)



     This Agreement is entered into as of October 29, 1996, by and between
Aastrom Biosciences, Inc., a Michigan corporation (the "Company"), and Cobe
Laboratories, Inc., a Colorado corporation (the "Purchaser"), with respect to
the factual recitals set forth below.

     Certain terms used in this Agreement are defined in Section 1 of this
Agreement.

                                   RECITALS

     A.   The Company and the Purchaser previously entered into that certain
Stock Purchase Agreement dated as of October 22, 1993 (the "1993 Stock Purchase
Agreement"), pursuant to which the Purchaser purchased 10,000 shares of the
Company's Series C preferred stock.  Pursuant to Section 5.05 of the 1993 Stock
Purchase Agreement, the Company has a "put right" which obligates the Purchaser
to purchase up to $5 million of additional capital stock in the Company, under
the terms and provisions set forth therein (the "Company's Put Right").
Pursuant to Section 5.04 of the 1993 Stock Purchase Agreement, the Company
granted to the Purchaser certain preemptive rights to purchase additional shares
of the Company's capital stock when the Company has its initial public offering
("IPO") of stock registered with the Securities and Exchange Commission or
another equity financing (the "Purchaser's Preemptive Rights").

     B.   The Company has prepared Amended and Restated Articles of
Incorporation, a copy of which is attached hereto as Exhibit A (the "Amended
Articles"), which create 833,333 shares of Series F preferred stock (the
"Shares") having rights, privileges and preferences as set forth in the Amended
Articles.

     WHEREFORE, the parties hereto mutually agree as follows:

1.   Definitions.

          "1993 Stock Purchase Agreement" is defined in Recital A hereof.

          "Advisors" is defined in Section 4.4 hereof.

          "Amended Articles" is defined in Recital B hereof.

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<PAGE>
 
          "Closing" is defined in Sections 3.1 and 3.2 hereof.

          "Common Stock" is defined in Section 4.1 hereof.

          "Company's Put Right" is defined in Recital A hereof.

          "Conversion Shares" is defined in Section 4.1 hereof.

          "Disclosure Statement" is defined in Section 4.3 hereof.

          "Financial Statements" is defined in Section 4.3 hereof.

          "Investors' Rights Agreement is defined in Section 7 hereof.

          "IPO" is defined in Recital A hereof.

          "Most Recent Financial Statements" is defined in Section 4.3 hereof.

          "Notice to Purchase" is defined in Section 2.3 hereof.

          "Prospectus" is defined in Section 4.3 hereof.

          "Purchaser's Preemptive Right" is defined in Recital A hereof.

          "Qualifying Financing" means any one of the following:

               a.  the Company entering into (or completing) a term sheet
agreement (or other agreement) with investors or an underwriter by December 1,
1997, which provides for: (i) a scheduled closing by February 1, 1998, (ii) a
public sale (i.e., an IPO) or private sale of equity securities of the Company,
the gross proceeds from which equity sale is to aggregate to at least $10
million, (iii) the proceeds of the sale are not designated by the investor for
specified limited purposes, (iv) the price per share for the sale is set by
mutual agreement between the Company and investors who invest at least $1
million, and (v) the sale of equity securities actually is consummated by
February 1, 1998; or

               b.  the Company entering into (or completing) a term sheet
agreement (or other agreement) by December 1, 1997 for the merger or sale of the
Company at a value of at least $85 million, with (i) a scheduled closing for the
merger or sale to be by February 1, 1998, and (ii) the merger or sale actually
being consummated by February 1, 1998; or

               c.  the Company's Board of Directors adopting an Operational Plan
for the Company to continue its operations in the ordinary course of business

                                       2
<PAGE>
 
through December 31, 1998, funded by the Company's own cash flow and other
resources, without requiring outside equity or debt investment in the Company,
and with said Operational Plan being consistent with the intent of the annual
Product Development Plan ("PDP") that is part of the Distribution Agreement
between the Company and the Purchaser.

          "Securities Act" is defined in Section 4.1 hereof.

          "Shares" is defined in Recital B hereof.

          2.  Commitment to Purchase Shares.

              2.1.  The Purchaser hereby commits to purchase from the Company up
to 833,333 shares of Series F preferred stock, at $6.00 per share, for an
aggregate of up to $5 million cash purchase price, in accordance with the
Company's Notice to Purchase and the terms of this Agreement.

              2.2.  If the Company elects to sell any shares of Series F
preferred stock to the Purchaser, in accordance with the terms of this
Agreement, the Company shall give to the Purchaser a written notice (the "Notice
to Purchase") which specifies the number of shares of Series F preferred stock
which the Company is calling upon the Purchaser to purchase, and the scheduled
date for the closing of said purchase. The Notice to Purchase may be given any
time up through September 1, 1997, and shall specify a Closing date for
consummating the purchase to be not less than 90 days after the Notice to
Purchase is delivered to the Purchaser.

              2.3.  The Company may give to the Purchaser not more than two
Notices to Purchase, such that the Purchaser is required to purchase the Shares
in not more than two increments. Each increment shall be for not less than $1
million worth of the Shares, and the first increment may be for as much as $5
million worth of the Shares.

              2.4.  Upon the Company completing an IPO, the Purchaser's
obligation to purchase additional shares of Series F preferred stock will
terminate.

          3.  Closing.

              3.1.  At each closing (the "Closing") for the purchase and sale of
an increment of the Shares pursuant to this Agreement, the parties shall execute
and deliver all necessary documents to consummate the Closing as specified by
this Agreement, and the Purchaser shall pay the full purchase price for the
Shares specified in the Notice to Purchase, with payment by wire transfer to the
Company's offices in Ann Arbor, Michigan.

                                       3
<PAGE>
 
              3.2.  At the Closing, to be held at the Company's offices in Ann
Arbor, Michigan, the Company shall deliver to the Purchaser (a) a stock
certificate representing the Shares purchased, (b) a copy of the Amended
Articles, evidencing filing with the Corporations and Securities Bureau of the
Department of Commerce of the State of Michigan, (c) a certificate signed by the
Secretary of the Company evidencing that the necessary actions by the Company's
Board of Directors and shareholders have been taken to approve the
authorization, issuance and sale of the Shares pursuant to this Agreement, (d)
an opinion of legal counsel to the Company substantially in the form attached
hereto as Exhibit B, which opinion shall be addressed to the Purchaser and dated
the date of the Closing, and (e) a certificate signed by the President of the
Company confirming that the representations and warranties of the Company
contained in this Agreement remain true and correct in all material respects at
and as of the Closing, and that all of the covenants and agreements of the
Company contained in this Agreement and required to be performed on or prior to
the Closing shall have been performed in all material respects.

          4.  Representations and Warranties of the Purchaser. In order to
induce the Company to sell the Shares to the Purchaser, the Purchaser hereby
acknowledges, represents, warrants and agrees as follows:

              4.1.  None of the Shares of Series F Stock are (and the shares of
common stock, no par value ("Common Stock") issuable upon conversion thereof
("Conversion Shares") will not be) registered under the Securities Act of 1933
(as amended, the "Securities Act") or any state securities laws. The Purchaser
understands that the sale of the Shares is intended to be exempt from
registration under Section 4(2) of the Securities Act and/or the provisions of
Regulation D promulgated thereunder, based, in part, upon the representations,
warranties and agreements contained in this Agreement.

              4.2.  Neither the Securities and Exchange Commission nor any state
securities commission has approved any of the Shares or passed upon or endorsed
the merits of this transaction.

              4.3.  Prior to its execution of this Agreement, the Purchaser has
received from the Company (i) the draft Registration Statement on Form S-1 for
the Company dated August, 1996, together with a supplemental update thereto
dated October 3, 1996 (collectively called the "Disclosure Statement"), (ii) a
copy of the Amended Articles, for the purpose of creating the Series F Stock,
and (iii) the audited financial statements of the Company for the year ended
June 30, 1996, and the unaudited financial statements of the Company for the
month ended September 30, 1996 (the "Most Recent Financial Statements")
(collectively, the "Financial Statements").

                                       4
<PAGE>
 
              4.4.  The Purchaser acknowledges that all documents, records and
books pertaining to the investment in the Shares, including the Disclosure
Statement, have been made available for inspection by the Purchaser, or by its
attorney, accountant, purchaser representative and/or tax advisor (collectively,
the "Advisors") and that the Purchaser and/or its Advisors have completed such
review as they deem to be necessary to make the decision to purchase the Shares.

              4.5.  The Purchaser has reviewed the merits and risks of an
investment in the Shares. The Purchaser and the Advisors have had a reasonable
opportunity to ask questions of and receive answers from members of management
of the Company concerning the offer and sale of the Shares and all such
questions have been answered to the full satisfaction of the Purchaser.

              4.6.  In evaluating the suitability of an investment in the
Shares, the Purchaser has not relied upon any representation or other
information (oral or written) other than as contained in documents or answers to
questions so furnished to the Purchaser or its Advisors by the Company.

              4.7.  No oral or written representations have been made or oral or
written information furnished to the Purchaser or its Advisors in connection
with this Agreement which were in any way inconsistent with the information
provided to the Purchaser or its Advisors, including the Disclosure Statement.

              4.8.  The Purchaser, together with the Advisors, have such
knowledge and experience in financial, tax and business matters so as to enable
each of them to utilize the information made available to each of them in
connection with the purchase of the Shares to evaluate the merits and risks of
an investment in the Shares and to make an informed investment decision with
respect thereto.

              4.9.  The Purchaser is not relying on the Company with respect to
the tax and other economic considerations of an investment in the Shares, and
the Purchaser has relied on the advice, or has consulted with, only its own
Advisors concerning tax matters.

              4.10. The Purchaser is acquiring the Shares solely for its own
account, for investment, and not with a view to or for subdivision, resale or
distribution, in whole or in part, and no other person has or will have a direct
or indirect beneficial interest in the Shares, other than for any partner or
shareholder owners of the Purchaser, if any.

                                       5
<PAGE>
 
              4.11.  The Purchaser must bear the economic risk of the investment
indefinitely because none of the Shares of Series F Stock (or Conversion Shares)
may be sold, hypothecated or otherwise disposed of unless (i) subsequently
registered under the Securities Act and applicable state securities laws, or
(ii) an exemption from registration is available at that time. Legends shall be
placed on the Shares (and the Conversion Shares) to the effect that they have
not been registered under the Securities Act or applicable state securities laws
and appropriate notations thereon will be made in the Company's stock books.

              4.12.  The Purchaser has adequate means of providing for the
Purchaser's current financial needs and foreseeable contingencies and the
Purchaser accepts the fact that an investment in the Shares will not be liquid.

              4.13.  The Purchaser is aware that an investment in the Shares
involves a number of very significant risks and, in particular, acknowledges
that the Company is in the development stage. The Purchaser understands that the
risks associated with an investment in the Shares could result in, and the
Purchaser can sustain, a complete loss of its investment.

              4.14.  The Purchaser is an "accredited investor" as such term is
defined in the regulations promulgated under the Securities Act.

              4.15.  The Purchaser represents that it has full power and
authority to execute and deliver this Agreement and all other related agreements
and certificates and to carry out the provisions hereof and thereof and to
purchase and hold the Shares, and this Agreement is a legal, valid and binding
obligation of the Purchaser. The execution and delivery of this Agreement will
not violate or be in conflict with any order, judgment, injunction, agreement or
controlling document to which the Purchaser is a party or by which it is bound.

              4.16.  The Purchaser represents to the Company that the
information contained herein may be relied upon by the Company in determining
the availability of an exemption from registration under federal and state
securities laws. The Purchaser further represents and warrants that it will
notify the Company immediately upon the occurrence of any material change to the
information contained herein occurring prior to the Company's issuance of the
Shares.

              4.17.  The Purchaser is unaware of, and in no way relying on, any
form of general solicitation or general advertising in connection with the offer
and sale of the Shares.

              4.18.  The Purchaser agrees that the Shares may not be sold,
mortgaged, pledged, hypothecated or otherwise transferred unless the Shares are

                                       6
<PAGE>
 
registered under the Securities Act and applicable state securities laws or are
exempt from registration thereunder; and that the certificate evidencing the
Shares will contain a customary Securities Act legend with respect to the
foregoing transfer restriction.

          5.  Representations and Warranties of the Company. The Company
represents and warrants to the Purchaser that:

              5.1.  Organization, Qualifications and Corporate Power. The
Company is a corporation duly incorporated, validly existing and in good
standing under the laws of the State of Michigan and is duly licensed or
qualified to transact business as a foreign corporation and is in good standing
in each other jurisdiction in which the nature of the business transacted by it
or the character of the properties owned or leased by it requires such licensing
or qualification. The Company has the corporate power and authority to own and
hold its properties and to carry on its business as now conducted and as
proposed to be conducted, to execute, deliver and perform this Agreement, to
issue, sell and deliver the Series F Stock, and to issue and deliver the
Conversion Shares as provided in the Amended Articles.

              5.2. Authorization of Agreement.

                   a.  The execution and delivery by the Company of this
Agreement, the performance by the Company of its obligations hereunder, the
issuance, sale and delivery of the Series F Stock and the issuance and delivery
of the Conversion Shares have been duly authorized by all requisite corporate
action and will not violate any provision of law, any order of any court or
other agency of government, the Amended Articles or the Bylaws of the Company
(the "Bylaws"), or any provision of any indenture, agreement or other instrument
to which the Company or any of its properties or assets is bound, or conflict
with, result in a breach of or constitute (with due notice or lapse of time or
both) a default under any such indenture, agreement or other instrument, or
result in the creation or imposition of any lien, charge, restriction, claim or
encumbrance of any nature whatsoever upon any of the properties or assets of the
Company.

                   b.  The Series F Stock has been duly authorized and, when
issued in accordance with this Agreement, will be validly issued, fully paid and
nonassessable shares of the Company with no personal liability attaching to the
ownership thereof and will be free and clear of all liens, charges,
restrictions, claims and encumbrances imposed by or through the Company except
as set forth herein. The Conversion Shares have been duly reserved for issuance
upon conversion of the Series F Stock and, when so issued, will be duly
authorized, validly issued, fully paid and nonassessable shares of Common Stock
with no personal liability attaching to the ownership thereof and, so long as
the Series F

                                       7
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Stock tendered for conversion is free and clear of liens or encumbrances, will
be free and clear of all liens, charges, restrictions, claims and encumbrances
imposed by or through the Company except as set forth herein. Neither the
issuance, sale or delivery of the Series F Stock nor the issuance or delivery of
the Conversion Shares is subject to any preemptive right of stockholders of the
Company or to any right of first refusal or other right in favor of any person
which right has not been waived.

              5.3.  Validity. This Agreement has been duly executed and
delivered by the Company and constitutes the legal, valid and binding obligation
of the Company, enforceable in accordance with its terms.

              5.4.  Authorized Capital Stock. The authorized capital stock of
the Company consists of 12,200,000 shares of Preferred Stock, and 21,500,000
shares of Common Stock. Immediately prior to the Closing, 2,829,735 shares of
Common Stock and 9,451,766 shares of Preferred Stock will be validly issued and
outstanding, fully paid and nonassessable with no personal liability attaching
to the ownership thereof. The stockholders of record and holders of
subscriptions, warrants, options, convertible securities, and other rights
(contingent or other), if any, to purchase or otherwise acquire equity
securities of the Company prior to the Closing Date and the number of shares of
Common Stock and the number of such subscriptions, warrants, options,
convertible securities, and other such rights, if any, held by each, are as set
forth in the Disclosure Statement and/or in Schedule 6.4 attached hereto. The
designations, powers, preferences, rights, qualifications, limitations and
restrictions in respect of each class of authorized capital stock of the Company
are as set forth in the Amended Articles, a copy of which has previously been
delivered to the Purchaser, and all such designations, powers, preferences,
rights, qualifications, limitations and restrictions are valid, binding and
enforceable and in accordance with all applicable laws. Except as set forth in
the attached Schedule 6.4 or in the Disclosure Statement, (a) no person owns of
record or is known to the Company to own beneficially any share of Common Stock,
(b) no subscription, warrant, option, convertible security, or other right
(contingent or other) to purchase or otherwise acquire equity securities of the
Company is authorized or outstanding and (c) there is no commitment by the
Company to issue shares, subscriptions, warrants, options, convertible
securities, or other such rights or to distribute to holders of any of its
equity securities any evidence of indebtedness or asset. Except as provided for
in the Amended Articles or as set forth herein, the Company has no obligation
(contingent or other) to purchase, redeem or otherwise acquire any of its equity
securities or any interest therein or to pay any dividend or make any other
distribution in respect thereof. Except as set forth herein or in the Disclosure
Statement, there are no voting trusts or agreements, stockholders agreements,
pledge agreements, buy-sell agreements, rights of first refusal, preemptive
rights or proxies relating to any securities of the Company (whether or

                                       8
<PAGE>
 
not the Company is a party thereto). All of the outstanding securities of the
Company were issued in compliance with all applicable Federal and state
securities laws.

              5.5.  Litigation.

                    Except as disclosed in Schedule 5.5 delivered to the
Purchaser, there is no (a) action, suit, claim, proceeding or investigation
pending or, to the best of the Company's knowledge, threatened against or
affecting the Company or its directors, officers, or management, at law or in
equity, or before or by any Federal, state, municipal or other governmental
department, commission, board, bureau, agency or instrumentality, domestic or
foreign, (b) arbitration proceeding relating to the Company pending under
collective bargaining agreements or otherwise or (c) governmental inquiry
pending or, to the best of the Company's knowledge, threatened against or
affecting the Company (including without limitation any inquiry as to the
qualification of the Company to hold or receive any license or permit), and, to
the best knowledge of the Company, there is no basis for any of the foregoing.
Without waiving any applicable attorney-client privilege, the Company has not
received any opinion or memorandum or legal advice from legal counsel to the
effect that it is exposed, from a legal standpoint, to any liability or
disadvantage which may be material to its business, prospects, financial
condition, operations, property or affairs. To the best knowledge of the
Company, the Company is not in default with respect to any order, writ,
injunction or decree known to or served upon the Company of any court or of any
Federal, state, municipal or other governmental department, commission, board,
bureau, agency or instrumentality, domestic or foreign.

              5.6.  Financial Statements. The Company has furnished to the
Purchaser the Financial Statements. The Financial Statements are true and
correct in all material respects and have been prepared in accordance with
generally accepted accounting principles. The balance sheets included in the
respective Financial Statements accurately reflect the financial condition and
all assets and liabilities of the Company at the times referred to therein. The
statements of income and cash flows accurately reflect the operations of the
Company for the periods referred to therein. There are no undisclosed
liabilities in the Financial Statements.

              5.7.  No Convictions. To the best of the knowledge of the Company,
during the past ten (10) years, none of the directors, officers, or management
of the Company have been arrested or convicted of any material crime, including
any felony (whether material or not), have been indicted, have been bankrupt nor
have any of them been restricted in any way from bidding on contracts with the
government of the United States.

                                       9
<PAGE>
 
              5.8.  Brokers. The Company has no knowledge of any brokerage or
finders fee due in conjunction with the transactions contemplated by this
Agreement.

              5.9.  Subsidiaries. The Company has no subsidiaries. The Company
does not (a) own of record or beneficially, directly or indirectly: (1) any
shares of capital stock or securities convertible into capital stock of any
corporation; or (2) any participating interest in any partnership, joint venture
or other non-corporate business enterprise; or (b) control, directly or
indirectly, any other entity.

              5.10. Directors and Officers. The Disclosure Statement sets forth
the names of the directors and officers of the Company, together with the title
of each such person.

              5.11. No Material Adverse Change. Since the date of the Most
Recent Financial Statements, (a) there has been no material adverse change in
the assets, liabilities or financial condition of the Company from that
reflected in the Most Recent Financial Statements, except for changes in the
ordinary course of business, and (b) none of the business, prospects,
operations, property or affairs of the Company has been materially adversely
affected by any occurrence or development, individually or in the aggregate,
whether or not insured against.

              5.12. Taxes. The Company has filed all tax returns, Federal,
state, county and local, required to be filed by it, and the Company has paid
all taxes shown to be due by such returns as well as all other taxes,
assessments and governmental charges which have become due or payable, including
without limitation all taxes which the Company is obligated to withhold from
amounts owing to employees, creditors and third parties. All such taxes with
respect to which the Company has become obligated pursuant to elections made by
the Company in accordance with generally accepted practice have been paid and
adequate reserves have been established for all taxes accrued but not yet
payable. The Federal income tax returns of the Company have never been audited
by the Internal Revenue Service. No deficiency assessment with respect to or
proposed adjustment of the Company's Federal, state, county or local taxes is
pending or, to the best of the Company's knowledge, threatened. There is no tax
lien, whether imposed by any Federal, state, county or local taxing authority,
outstanding against the assets, properties or business of the Company. Neither
the Company nor, to the Company's knowledge, any of its stockholders, has ever
filed consent pursuant to Section 341(f) of the Code, relating to collapsible
corporations.

              5.13. Employee Benefit Plans. To the knowledge of the Company,
each of the Company's employee benefit plans (and each related trust or
insurance contract) complies in form and in operation in all respects with the

                                      10
<PAGE>
 
applicable requirements of the Employee Retirement Income Security Act of 1974
and the Internal Revenue Code of 1986, as amended. To the knowledge of the
Company, all required reports and descriptions have been filed or distributed
appropriately with respect to each employee benefit plan. There have been no
prohibited transactions with respect to any employee benefit plan. No fiduciary
has any liability for breach of fiduciary duty or any other failure to act or
comply in connection with the administration or investment of the assets of any
employee benefit plans. No charge, complaint, action, suit, proceeding, hearing,
investigation, claim, or demand with respect to the administration or the
investment of the assets of any employee benefit plan (other than routine claims
for benefits) is pending or, to the Company's knowledge, threatened. The Company
and its directors and officers (and employees with responsibility for employee
benefits matters) have no knowledge of any basis for any such charge, complaint,
action, suit, proceeding, hearing, investigation, claim, or demand.

              5.14.  Title to Properties. The Company has good and marketable
title to its properties and assets reflected in the Financial Statements or
acquired by it since the date of the Financial Statements (other than for
equipment leased pursuant to financing leases, and other than properties and
assets disposed of in the ordinary course of business since the date of the
Financial Statements), and all such properties and assets are free and clear of
mortgages, pledges, security interests, liens, charges, claims, restrictions and
other encumbrances, except for equipment financing leases, and for liens to
secure payment of obligations reflected in the Financial Statements and for
current taxes not yet due and payable, and minor imperfections of title, if any,
not material in nature or amount and not materially detracting from the value or
impairing the use of the property subject thereto or impairing the operations or
proposed operations of the Company.

              5.15.  Leasehold Interests. Each lease or agreement to which the
Company is a party under which it is a lessee of any property, real or personal
is a valid and enforceable agreement without any material default of the Company
thereunder and, to the best of the Company's knowledge, without any default by
the Company of any material term thereunder; the Company has not been notified
of any default and has no reason to believe that it is in default of any term
thereunder. To the best of the Company's knowledge, no other party to any such
lease or agreement is in default of a material term thereunder. No event has
occurred and is continuing which, with due notice or lapse of time or both,
would constitute a default or event of default by the Company under any such
lease or agreement or, to the best of the Company's knowledge, by any other
party thereto. The Company's possession of such property has not been disturbed
and, to the best of the Company's knowledge, no claim has been asserted against
the Company adverse to its rights in such leasehold interests.

                                      11
<PAGE>
 
              5.16.  Insurance. The Company maintains as to its properties and
business, with financially sound and reputable insurers, insurance against such
casualties and contingencies and of such types and in such amounts as is
customary for companies similarly situated.

              5.17.  Other Agreements. With respect to each material contract to
which the Company is a party, the Company and, to the best of the Company's
knowledge, each other party thereto, have in all material respects performed all
the obligations required to be performed by them to date, have received no
notice of default and are not in default (with due notice or lapse of time or
both) under any material lease, agreement or contract now in effect to which the
Company is a party or by which it or its property may be bound. The Company has
no present expectation or intention of not fully performing all its obligations
under each such material lease, contract or other agreement and the Company has
no knowledge of any breach or anticipated breach by the other party to any
contract or commitment to which the Company is a party.

              5.18.  Patents, Trademarks, Etc.

                     a.  The Disclosure Statement describes all material
patents, patent rights, patent applications, trademarks, trademark applications,
service marks, service mark applications, trade names and copyrights, and all
material applications for such which are in the process of being prepared, owned
by or registered in the name of the Company, or of which the Company is a
licensor or licensee or in which the Company has any right, and in each case a
brief description of the nature of such right. The Disclosure Statement contains
an accurate and complete description of all material licenses. The Company is in
compliance in all material respects with each of such licenses. The Company owns
or possesses adequate licenses or other rights to use all patents, patent
applications, trademarks, trademark applications, service marks, service mark
applications, trade names, copyrights, manufacturing processes, formulae, trade
secrets and know how (collectively, "Intellectual Property") necessary to the
conduct of its business as conducted, and no claim is pending or, to the best of
the Company's knowledge, threatened to the effect that the operations of the
Company infringe upon or conflict with the asserted rights of any other person
under any Intellectual Property, and, to the best knowledge of the Company,
there is no basis for any such claim (whether or not pending or threatened). No
claim is pending or threatened to the effect that any such Intellectual Property
owned or licensed by the Company, or which the Company otherwise has the right
to use, is invalid or unenforceable by the Company, or that the Company is not
in compliance with any term or condition of a license, and there is no basis for
any such claim (whether or not pending or threatened). The Company has not
granted or assigned to any other person or entity any right to manufacture, have
manufactured, assemble or sell the products or proposed products or to provide

                                      12
<PAGE>
 
the services or proposed services of the Company except as set forth in the
Disclosure Statement.

                     b.  The Company has taken reasonable security measures to
protect the secrecy, confidentiality, and value of the Company's trade secrets;
any of their employees and any other persons who, either alone or in concert
with others, developed, invented, discovered, derived, programmed, or designed
these secrets, or who have knowledge of or access to information relating to
them, have entered into agreements protecting the confidentiality thereof.
 
              5.19.  Proprietary Information of Third Parties. To the best of
the Company's knowledge, no third party has claimed or has reason to claim that
any person employed by or affiliated with the Company has (a) violated or may be
violating any of the terms or conditions of his employment, non-competition or
nondisclosure agreement with such third party, (b) disclosed or may be
disclosing or utilized or may be utilizing any trade secret or proprietary
information or documentation of such third party or (c) interfered or may be
interfering in the employment relationship between such third party and any of
its present or former employees. No third party has requested information from
the Company which suggests that such a claim might be contemplated. To the best
of the Company's knowledge, no person employed by or affiliated with the Company
has employed or proposes to employ any trade secret or any information or
documentation proprietary to any former employer, and to the best of the
Company's knowledge, no person employed by or affiliated with the Company has
violated any confidential relationship which such person may have had with any
third party, in connection with the development, manufacture or sale of any
product or proposed product or the development or sale of any service or
proposed service of the Company, and the Company has no reason to believe there
will be any such employment or violation. To the best of the Company's
knowledge, none of the execution or delivery of this Agreement, or the carrying
on of the business of the Company as officers, employees or agents by any
officer, director or key employee of the Company, or the conduct or proposed
conduct of the business of the Company, will conflict with or result in a breach
of the terms, conditions or provisions of or constitute a default under any
contract, covenant or instrument under which any such person is obligated.

              5.20.  Compliance With Law. To the best of the Company's
knowledge, the Company has complied with all laws, rules, regulations and orders
applicable to its business, operations, properties, assets, products and
services, the violation of which would have a material adverse effect upon the
Company, and the Company has all necessary permits, licenses and other
authorizations required to conduct its business as it is now conducted. To the
best of the Company's knowledge, there is no existing law, rule, regulation or
order, and the
                                       13
<PAGE>
 
Company after due inquiry is not aware of any proposed law, rule, regulation or
order, whether Federal or state, which would prohibit or restrict the Company
from, or otherwise materially adversely affect the Company in, conducting its
business, in which it is now conducting business or in which it proposes to
conduct business, other than the customary governmental approvals required for
medical products. Without limiting the foregoing in any manner, to the best of
the Company's knowledge, the Company has complied in all material respects with
all applicable laws relating to the employment of labor, including provisions
relating to wages, hours, equal opportunity, collective bargaining and the
payment of Social Security and other taxes, with the Employee Retirement Income
Security Act of 1974, as amended, with the Occupational Health and Safety Act,
and with the Americans With Disabilities Act. To the best of the Company's
knowledge, the Company is in full compliance with the Immigration Reform and
Control Act of 1986, as amended, and all key employees who are not United States
citizens are currently authorized under United States immigration laws to hold
United States employment and will continue to have such employment authorization
throughout the term of the Series F Stock investment, and are otherwise in
compliance with United States immigration laws.

              5.21.  Loans and Advances. The Company does not have any
outstanding loans or advances to any person and is not obligated to make any
such loans or advances, except as reflected on the Financial Statements, and
except, in each case, for advances to employees of the Company in respect of
reimbursable business expenses anticipated to be incurred by them in connection
with their performance of services for the Company. In the near future, the
Company expects to borrow funds from the State Treasurer of the State of
Michigan pursuant to a pending convertible loan commitment, as described in
Section 12 hereof.

              5.22.  Assumptions, Guaranties, Etc. of Indebtedness of Other
Persons. Except as disclosed in the Financial Statements, the Company has not
assumed, guaranteed, endorsed or otherwise become directly or contingently
liable on any indebtedness of any other person (including, without limitation,
liability by way of agreement, contingent or otherwise, to purchase, to provide
funds for payment, to supply funds to or otherwise invest in the debtor, or
otherwise to assure the creditor against loss), except for guaranties by
endorsement of negotiable instruments for deposit or collection in the ordinary
course of business.

                                      14
<PAGE>
 
              5.23.  Governmental Approvals. Subject to the accuracy of the
representations and warranties of the Purchaser set forth in Section 4, no
registration or filing with, or consent or approval of or other action by, any
Federal, state or other governmental agency or instrumentality is or will be
necessary for the valid execution, delivery and performance by the Company of
this Agreement, the issuance, sale and delivery of the Series F Stock or, upon
conversion of the Series F Stock, the issuance and delivery of the Conversion
Shares, other than (a) filings pursuant to state securities laws (all of which
filings have been or will be made by the Company) in connection with the sale of
the Series F Stock and (b) with respect to the Registration Rights as set forth
in Section 7 hereof, the registration of the shares covered thereby with the
Commission and filings pursuant to state securities laws.

              5.24.  Disclosure. The Company's Disclosure Statement, contains
only true and accurate facts and representations, and does not contain any
untrue information and does not omit any material fact necessary to make the
statements contained therein not misleading. Neither this Agreement, nor any
Schedule or Exhibit to this Agreement, contains an untrue statement of a
material fact or omits a material fact necessary to make the statements
contained herein or therein not misleading. None of the statements, documents,
certificates or other items prepared or supplied by the Company with respect to
the transactions contemplated hereby contains an untrue statement of a material
fact or omits a material fact necessary to make the statements contained therein
not misleading. As of the date hereof, no facts have come to the attention of
the Company which would, in its opinion, require the Company to revise or
amplify the Disclosure Statement.

              5.25.  Offering of Shares. This Agreement is being made by the
Company pursuant to an exemption from the registration requirements of the
Securities Act.

              5.26.  Transactions With Affiliates. Except as set forth in the
Disclosure Statement, no director, officer, employee or stockholder of the
Company, or member of the family of any such person, or any corporation,
partnership, trust or other entity in which any such person, or any member of
the family of any such person, has a substantial interest in or is an officer,
director, trustee, partner or holder of more than 5% of the outstanding capital
stock thereof, is a party to any transaction with the Company, including any
contract, agreement or other arrangement providing for the employment of,
furnishing of services by, rental of real or personal property from or otherwise
requiring payments to any such person or firm.

                                      15
<PAGE>
 
          6.  Covenants of the Company.

              6.1.  Ordinary Course of Business. From the date hereof through
the last Closing under this Agreement, the Company shall continue to operate the
Company's business in the ordinary course, expecting only for any extraordinary
activity as may be approved by the Company's Board of Directors.

              6.2.  Updated Information. From the date hereof through the last
Closing under this Agreement, the Company shall promptly inform the Purchaser of
any new facts or circumstances which come to the attention of the Company and
which are likely to have any material adverse effect on the Company or which
constitute any material adverse variation from the representations made by the
Company herein.

              6.3.  Board of Directors Seat. From the date hereof and continuing
so long as the Purchaser owns at least 15% of the issued and outstanding common
stock of the Company (calculated on the basis of all preferred stock being
converted into common stock pursuant to the conversion formula set forth in the
Company's Restated Articles of Incorporation), the Company will use reasonable
and good faith efforts to cause to be elected as a member of the Company's Board
of Directors one person nominated by the Purchaser; provided that the Board of
Directors determines in the exercise of its fiduciary duties that the
Purchaser's nominee is qualified to serve on the Board. If the Board so
determines that the nominee is not qualified, then the Purchaser may make
further nominations until the Board determines that the nominee is qualified.

          7.  Stock Registration Rights. The Shares shall be entitled to the
benefits and subject to the terms of the stock registration rights provisions as
set forth in Sections 2.4 through 2.14, inclusive, of the Company's Amended and
Restated Investors' Rights Agreement dated as of April 7, 1992, as amended (the
"Investors' Rights Agreement"), a copy of which has been furnished to the
Purchaser.

          8.  Market Stand-off Restriction. The Purchaser (and any other holders
of the Shares) shall abide by the 180-day "market stand-off" restriction on the
sale of the Shares following the Company's public stock offering, as applicable
to all other holders of the Company's preferred stock, and/or as required by the
Investors' Rights Agreement.

          9.  Information Rights. The holder(s) of the Shares shall be entitled
to receive the Company's information and financial statements as specified in
Sections 3.1 through 3.7, inclusive, of the Investors' Rights Agreement.

                                      16
<PAGE>
 
          10.  Company's Put Right. To the extent that the Purchaser purchases
shares of Series F preferred stock pursuant to this Agreement, the Purchaser's
obligations under the Company's Put Right (as specified in Section 5.05 of the
1993 Stock Purchase Agreement) shall be reduced on a dollar for dollar basis.
For example, if the Purchaser purchases $1 million of Series F preferred stock
pursuant to the terms of this Agreement, then the Purchaser's obligation under
the Company's Put Right shall be reduced from $5 million to $4 million.

          11.  Purchaser's Preemptive Rights. To the extent that the Purchaser
purchases shares of Series F preferred stock pursuant to this Agreement, the
shares of Series F Preferred Stock purchased by the Purchaser will be excluded
from the determination of the Purchaser's percentage ownership of the Company
for purposes of calculating the Purchaser's Preemptive Rights (as granted
pursuant to Section 5.04 of the 1993 Stock Purchase Agreement).

          12.  Condition. The Purchaser's obligations under this Agreement are
conditional upon the Company also entering into a Convertible Loan Commitment
Agreement with the State Treasurer of the State of Michigan for $5,000,000, in
substantially the same form and substance as was approved by the Company's Board
of Directors in September 1996.

          13.  General Provisions.

               13.1.  Irrevocability; Binding Effect. The Purchaser hereby
acknowledges and agrees that the commitment hereunder is irrevocable by the
Purchaser, except as required by applicable law, and that this Agreement shall
be binding upon and inure to the benefit of the parties and their respective
successors, legal representatives, and permitted assigns.

               13.2.  Modification. This Agreement shall not be modified or
waived except by an instrument in writing signed by the party against whom any
such modification or waiver is sought.

               13.3.  Notices. A notice or other communication required or
permitted to be given hereunder shall be in writing and shall be given by any
means, including without limitation, mail, express delivery service, or
facsimile. Any notice or other communication shall be deemed given at the time
it is received at the party's address set forth on the signature page of this
Agreement, or at such other address as the party shall have furnished in writing
in accordance with the provisions of this Section 13.3.

               13.4.  Assignability. This Agreement and the rights, interests
and obligations hereunder are not transferable or assignable by the Purchaser,

                                      17
<PAGE>
 
except to an affiliate of the Purchaser who qualifies as an "accredited
investor," and the Purchaser further agrees that the transfer or assignment of
the Shares shall be made only in accordance with all applicable laws.

               13.5.  Applicable Law. This Agreement shall be governed by and
construed in accordance with the internal laws of the state of Michigan without
regard to its conflicts of laws principles.

               13.6.  Confidentiality. The Purchaser acknowledges and agrees
that any information or data it has acquired from or about the Company,
including the information contained in the Disclosure Statement and the
Financial Statements, but excluding any information which was in the public
domain, was received in confidence. The Purchaser agrees not to divulge,
communicate or disclose, except as may be required by law or for the performance
of this Agreement, or use to the detriment of the Company or for the benefit of
any other person or persons, or misuse in any way, any confidential information
of the Company, including any scientific, technical, trade or business secrets
of the Company and any scientific, technical, trade or business materials that
are treated by the Company as confidential or proprietary, including, but not
limited to, ideas, discoveries, inventions, developments and improvements
belonging to the Company and confidential information obtained by or given to
the Company about or belonging to third parties.

               13.7.  Entirety. This Agreement, together with the Exhibits,
Schedules and other documents referenced herein, constitutes the entire
agreement between the Purchaser and the Company with respect to the purchase and
sale of the Series F Shares, and supersedes all prior oral or written agreements
and understandings, if any, relating thereto. The terms and provisions of this
Agreement may be waived, or consent for the departure therefrom granted, only by
a written document executed by the party entitled to the benefits of such terms
or provisions.

               13.8.  Survival. The Purchaser's representations and warranties
made in this Agreement shall survive the execution and delivery hereof and of
the Shares.

               13.9.  Expenses. Each of the parties hereto shall pay its own
fees and expenses (including the fees of any attorneys, accountants, appraisers
or others engaged by such party) in connection with this Agreement and the
transactions contemplated hereby whether or not the transactions contemplated
hereby are consummated.

               13.10.  Construction. All pronouns and any variations thereof
used herein shall be deemed to be to the masculine, feminine, neuter, singular
or

                                      18
<PAGE>
 
plural as the identity of the person or persons referred to may require.
Paragraph titles are for descriptive purposes only and shall not control or
alter the meaning of this Agreement as set forth in the text.

               13.11.  Severability. Each provision of this Agreement shall be
considered separable and if for any reason any provision or provisions hereof
are determined to be invalid or contrary to applicable law, such invalidity
shall not impair the operation of or affect the remaining portions of this
Agreement, so long as the material economic benefits remain enforceable.

                                      19
<PAGE>
 
               13.12.  Counterparts. This Agreement may be executed in one or
more counterparts each of which shall be deemed an original, but all of which
shall together constitute one and the same instrument. Signatures may be
transmitted by facsimile.

     IN WITNESS WHEREOF, the parties have executed and delivered this Agreement
as of the date set forth on the first page of this Agreement.

                                 COMPANY:

                                     Aastrom Biosciences, Inc.,
                                     a Michigan corporation
                                     Domino's Farms, Lobby L
                                     24 Frank Lloyd Wright Drive
                                     Ann Arbor, MI 48105
                                     Fax: 313/930-5546


 
                                     By:    /s/ R. Douglas Armstrong
                                         ---------------------------
                                         R. Douglas Armstrong, Ph.D.,
                                     President



                                 PURCHASER:

                                     Cobe Laboratories, Inc.,
                                     a Colorado corporation
                                     1185 Oak Street
                                     Lakewood, CO 80215
                                     Fax: 303/230-4195

                                     By:  /s/  Edward C. Wood
                                        ----------------------

                                       20
<PAGE>
 
                                 SCHEDULE 5.5


                                  Litigation


     1.   R. M. Schwartz.  The Company has written letters to a former employee,
Richard M. Schwartz, Ph.D. and Dr. Schwartz's new employer, SyStemix, (i)
reminding them of Dr. Schwartz's duty to maintain strict confidentiality as to
the Company's trade secrets; and (ii) asking if there has been any breach of
this confidentiality obligation; and (iii) commenting that a new invention by
Systemix's appears to be derived from the Company's trade secrets.  Systemix and
Dr. Schwartz have denied any use of the Company's trade secrets.  The Company
has reserved its rights in this matter, but does not presently contemplate
pursuing this potential claim in the near future.

     2.   Sundberg-Ferar.  The Company has commenced an arbitration proceeding
against Sundberg-Ferar ("S-F") for what the Company asserts to be a breach by S-
F of the contractual obligations of S-F to not solicit away from the Company's
employment its employees.  This arbitration is for the Company to seek damages
recovery from S-F, although if the Company is not successful in this
arbitration, then S-F may seek to recover its attorney's fees incurred in
defending the arbitration proceedings.

                                      21
<PAGE>
 
                                 SCHEDULE  6.4


                                Stock Schedule



                    



                        Shares Issued and Outstanding    Shares Authorized
                                                   
Preferred Stock
Series A                          2,500,000                  2,500,000
Series B                          3,030,000                  3,030,000
Series C                             10,000                     10,000
Series D                          2,500,001                  3,000,000
Series E                          1,617,647                  1,617,647
Series F                           *833,333                    833,333
Undesignated                          ---                    1,209,020

     Subtotals:                  10,490,981                 12,200,000


Common Stock                      2,829,735                 21,500,000


*  Shares to be sold to Cobe Laboratories, Inc., pursuant to this Agreement.

                                      22

Source: OneCLE Business Contracts.