<PAGE>

                                                                  EXECUTION COPY

================================================================================

                                                                   EXHIBIT 10.13

                            STOCK PURCHASE AGREEMENT

                         Dated as of September 30, 2003

                                      among

                                 VIACELL, INC.,
                             KOURION THERAPEUTICS AG

                                       and

                            THE SELLERS PARTY HERETO

================================================================================
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

                                TABLE OF CONTENTS

<TABLE>
<S>                                                                                   <C>
1.  DEFINITIONS; CERTAIN RULES OF CONSTRUCTION.........................................1
2.  PURCHASE AND SALE OF SHARES.......................................................11
            2.1.  Purchase and Sale of Shares.........................................11
            2.2.  Escrowed Shares.....................................................12
            2.3.  Contingent Shares...................................................13
            2.4.  Milestone Payments..................................................14
            2.5.  The Closing.........................................................15
            2.6.  Closing Deliveries..................................................15
            2.7.  Purchase Price Adjustment...........................................16
3.  REPRESENTATIONS AND WARRANTIES RELATING TO THE COMPANY............................16
            3.1.  Capitalization and Ownership........................................16
            3.2.  Corporate Organization..............................................17
            3.3.  Financial Statements................................................17
            3.4.  Absence of Certain Developments.....................................18
            3.5.  Powers and Authority................................................19
            3.6.  No Breaches, Violations or Consents.................................19
            3.7.  Title to and Condition of the Assets................................19
            3.8.  No Claims or Litigation.............................................19
            3.9.  Contracts...........................................................20
            3.10.  Intellectual Property..............................................20
            3.11.  Insurance..........................................................21
            3.12.  Bank Accounts and Powers of Attorney...............................22
            3.13.  Affiliated Transactions............................................22
            3.14.  Employees and Agents...............................................22
            3.15.  Employee Benefit Plans.............................................22
            3.16.  Tax Returns and Payments...........................................22
            3.17.  Disclosures........................................................23
            3.18.  Debt ..............................................................23
            3.19.  Real Property......................................................23
            3.20.  Environmental Matters..............................................23
            3.21.  Illegal Payments, etc..............................................24
            3.22.  Brokers' Fees......................................................24
            3.23.  Company Assets.....................................................24
            3.24.  Closing Date Net Working Capital Statement.........................24
4.  REPRESENTATIONS AND WARRANTIES RELATING TO THE SELLERS............................24
            4.1.  Authorization.......................................................25
            4.2.  No Violation or Approval............................................25
            4.3.  Title to Shares.....................................................25
            4.4.  Qualification of the Sellers........................................26
            4.5.  Restrictive Legends.................................................26
            4.6.  Brokers' Fees.......................................................27
5.  REPRESENTATIONS AND WARRANTIES OF VIACELL.........................................27
            5.1.  Organization and Standing...........................................27
            5.2.  ViaCell Subsidiaries................................................28
</TABLE>

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                                                        Stock Purchase Agreement
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<TABLE>
<S>                                                                                   <C>
            5.3.  Authority to Execute and Perform Agreements.........................28
            5.4.  Capitalization and Title to Shares..................................28
            5.5.  Financial Statements................................................29
            5.6.  No Material Adverse Change..........................................30
            5.7.  Tax Matters.........................................................31
            5.8.  Compliance with Laws................................................33
            5.9.  Consents; No Breach.................................................33
            5.10.  Actions and Proceedings............................................34
            5.11.  Contracts and Other Agreements.....................................34
            5.12.  Title to Properties; Absence of Liens and Encumbrances.............36
            5.13.  Condition and Sufficiency of Assets................................37
            5.14.  Intellectual Property..............................................37
            5.15.  Absence of Undisclosed Liabilities.................................38
            5.16.  Commercial Relationships...........................................38
            5.17.  Employee Benefit Plans.............................................38
            5.18.  Employee Relations.................................................39
            5.19.  Insurance..........................................................39
            5.20.  Environmental Compliance...........................................39
            5.21.  Bank Accounts and Powers of Attorney...............................40
            5.22.  Brokerage..........................................................40
            5.23.  Investment Company Act.............................................40
            5.24.  Full Disclosure....................................................40
            5.25.  Financial..........................................................41
6.  COVENANTS OF THE COMPANY AND THE SELLERS..........................................41
            6.1.  Closing ............................................................41
            6.2.  Expenses ...........................................................41
            6.3.  Sellers' Release....................................................41
            6.4.  Confidentiality.....................................................41
            6.5.  Further Assurances; Obligation to Satisfy Closing Conditions........42
7.  COVENANTS OF VIACELL..............................................................42
            7.1.  Financing...........................................................42
            7.2.  Company Employee Retention..........................................42
            7.3.  New Company Employment Contracts....................................42
            7.4.  Consultancy Arrangements............................................42
            7.5.  Advisory Board Position.............................................43
            7.6.  USSC Technology Committee...........................................43
            7.7.  European Operations.................................................43
            7.8.  Milestones..........................................................43
            7.9.  Institutional Obligations...........................................44
            7.10.  Change of Control..................................................44
8.  CONDITIONS TO VIACELL'S OBLIGATIONS AT THE CLOSING................................44
            8.1.  Representations and Warranties......................................44
            8.2.  Performance.........................................................44
            8.3.  Stock and Option Certificates.......................................44
            8.4.  Qualifications......................................................45
            8.5.  Absence of Litigation...............................................45
</TABLE>

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<TABLE>
<S>                                                                                   <C>
            8.6.  Legal Opinion.......................................................45
            8.7.  Consents, etc.......................................................45
            8.8.  Stockholder Approval................................................45
            8.9.  Proceedings and Documents...........................................45
            8.10.  Ancillary Agreements...............................................45
            8.11.  Financing..........................................................45
            8.12.  No Material Adverse Change.........................................45
            8.13.  Compliance Certificate.............................................45
            8.14.  Initial Budget.....................................................46
            8.15.  Company Employee Contracts.........................................46
            8.16.  Resignations.......................................................46
            8.17.  Supporting Documents...............................................46
            8.18.  Net Working Capital................................................46
9.  CONDITIONS TO THE COMPANY AND THE SELLERS' OBLIGATIONS AT THE CLOSING.............46
            9.1.  Representations and Warranties......................................46
            9.2.  Performance.........................................................47
            9.3.  Qualifications......................................................47
            9.4.  Absence of Litigation...............................................47
            9.5.  Legal Opinion.......................................................47
            9.6.  Consents, etc.......................................................47
            9.7.  Proceedings and Documents...........................................47
            9.8.  Note Escrow Agreement...............................................47
            9.9.  Series I Agreements.................................................47
            9.10.  Ancillary Agreements...............................................47
            9.11.  No Material Adverse Change.........................................47
            9.12.  Stock Certificates.................................................47
            9.13.  Compliance Certificate.............................................48
            9.14.  Financing..........................................................48
            9.15.  Initial Budget.....................................................48
            9.16.  Supporting Documents...............................................48
10.  TERMINATION......................................................................48
            10.1.  Termination of Agreement...........................................48
            10.2.  Effect of Termination..............................................49
11.  INDEMNIFICATION..................................................................49
            11.1.  Indemnification by the Sellers.....................................49
            11.2.  Time for Claims....................................................50
            11.3.  Third Party Claims.................................................51
            11.4.  No Circular Recovery...............................................52
            11.5.  Indemnity Escrow; Calculation of Several Liability.................53
            11.6.  Offset ............................................................54
            11.7.  Consequential Damages..............................................54
            11.8.  Knowledge and Investigation........................................54
            11.9.  Remedies Cumulative................................................54
            11.10.  Exclusive Remedy..................................................54
12.  MISCELLANEOUS....................................................................55
</TABLE>

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                                                        Stock Purchase Agreement
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<TABLE>
<S>                                                                                   <C>
            12.1.  Notices ...........................................................55
            12.2.  Succession and Assignment; No Third-Party Beneficiary..............56
            12.3.  Consent of Sellers.................................................56
            12.4.  Amendments and Waivers.............................................56
            12.5.  Provisions Concerning Sellers' Representative......................56
            12.6.  Entire Agreement...................................................57
            12.7.  Schedules; Listed Documents, etc...................................57
            12.8.  Counterparts.......................................................58
            12.9.  Severability.......................................................58
            12.10.  Headings..........................................................58
            12.11.  Governing Law.....................................................58
            12.12.  Dispute Resolution; Forum.........................................58
            12.13.  Specific Performance..............................................59
</TABLE>

                                      -iv-
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                                                        Stock Purchase Agreement
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                                    EXHIBITS

Exhibit A         Form of Notes
Exhibit B         Form of Escrow Agreement
Exhibit C         Form of Opinion by Company Counsel
Exhibit D         Form of Compliance Certificate
Exhibit E         Form of Opinion by ViaCell Counsel
Exhibit F         Initial Budget
Exhibit G         Closing Date Net Working Capital Statement/Net Working
                  Capital Accounting Principles

Exhibit H         Form of Assignment
Exhibit I         Form of Employment Agreement
Exhibit J         Series I Agreements
Exhibit K         Form of Note Escrow Agreement
Exhibit L         Transaction Fee Statement

                                    SCHEDULES

Schedule 1            Series A Sellers
Schedule 2            Common Sellers
Schedule 3            Escrowed Shares
Schedule 4            Company Options
Schedule 5            Contingent Shares
Schedule 6            Percentage Ownership
Schedule 3.1          Capitalization and Ownership
Schedule 3.3          Company Financial Statements
Schedule 3.4          Absence of Certain Developments
Schedule 3.5          Powers and Authority
Schedule 3.6          No Breaches, Violations or Consents
Schedule 3.7          Title to Assets
Schedule 3.9          Contracts
Schedule 3.10         Intellectual Property
Schedule 3.11         Insurance
Schedule 3.12         Bank Accounts and Powers of Attorney
Schedule 3.13         Transactions with Affiliates
Schedule 3.14         Employees and Agents
Schedule 3.15         Company Plans
Schedule 3.18         Debt
Schedule 3.19         Real Property
Schedule 3.22         Brokers
Schedule 4.2          Seller Consents
Schedule 4.6          Seller Brokers
Schedule 5.2          ViaCell Subsidiaries
Schedule 5.4          Capitalization of ViaCell
Schedule 5.5          ViaCell Financial Statements
Schedule 5.6          Material Adverse Changes

                                      -v-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

Schedule 5.7          ViaCell Tax Matters
Schedule 5.8          ViaCell Environmental Matters
Schedule 5.9          ViaCell Consents
Schedule 5.10         ViaCell Actions and Proceedings
Schedule 5.11         ViaCell Contracts
Schedule 5.12         ViaCell Real Property
Schedule 5.14         ViaCell Intellectual Property
Schedule 5.17         ViaCell Benefit Plans
Schedule 5.19         ViaCell Insurance
Schedule 5.21         ViaCell Bank Accounts and Powers of Attorney
Schedule 6.3          Seller Release

                                      -vi-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

                            STOCK PURCHASE AGREEMENT

         THIS STOCK PURCHASE AGREEMENT dated as of September 30, 2003 (as
amended or otherwise modified, the "Agreement") by and among ViaCell, Inc., a
Delaware corporation ("ViaCell" or "Buyer"), Kourion Therapeutics AG, a German
corporation (the "Company"), and the shareholders of the Company signatory
hereto (each a "Seller" and, collectively, the "Sellers").

                                    RECITALS

         WHEREAS, the Sellers are the record and beneficial owners of all of the
outstanding shares of capital stock of the Company (collectively, the "Shares"),
consisting of Series A Preference shares, no par value, of the Company (the
"Series A Shares") and Common Shares, no par value, of the Company (the "Common
Shares");

         WHEREAS, certain Sellers own and desire to sell all of the outstanding
Series A Shares to ViaCell, and the remaining Sellers, as well as the Series A
Sellers, own and desire to sell all of the outstanding Common Shares to ViaCell;

         WHEREAS, upon the sale of such Series A Shares and Common Shares to
ViaCell, ViaCell will own all of the outstanding equity interests in the
Company;

         WHEREAS, ViaCell desires to purchase the Series A Shares and the Common
Shares from the Sellers on the terms and subject to the conditions set forth in
this Agreement.

                                    AGREEMENT

         NOW THEREFORE, in consideration of the premises and mutual promises
herein made, and in consideration of the representations, warranties and
covenants herein contained, ViaCell, the Company and the Sellers hereby agree as
follows:

         1. DEFINITIONS; CERTAIN RULES OF CONSTRUCTION.

         As used herein, the following terms will have the following meanings:

        "Action" means any claim, action, cause of action or suit (whether in
contract or tort or otherwise), litigation (whether at law or in equity, whether
civil or criminal), controversy, assessment, arbitration, investigation,
hearing, charge, complaint, demand, notice or proceeding to, from, by or before
any Governmental Authority.

        "Affiliate" means, with respect to any specified Person at any time, (a)
each Person directly or indirectly controlling, controlled by or under direct or
indirect common control with such specified Person at such time, (b) each Person
who is at such time an officer or director of, or direct or indirect beneficial
holder of at least 20% of any class of the Equity Interests of, such specified
Person, (c) each Person that is managed by a common group of executive officers
and/or directors as such specified Person, (d) the Members of the Immediate
Family (i) of each officer, director or holder described in clause (b) and (ii)
if such specified Person is an
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

individual, of such specified Person and (e) each Person of which such specified
Person or an Affiliate (as defined in clauses (a) through (d)) thereof will,
directly or indirectly, beneficially own at least 20% of any class of Equity
Interests at such time.

        "Agreement" is defined in the Preamble.

        "Ancillary Agreements" means (i) the Notes, (ii) the Escrow Agreement,
(iii) any employment or consulting agreements with the Company or ViaCell in
effect following the Closing, and (iv) any other agreements as disclosed herein
that are necessary for the consummation of the Contemplated Transactions.

        "Assets" means assets held for or used in connection with and/or
necessary for the current and currently proposed operation of the Company.

        "Assignment" is defined in Section 2.6.1.

        "Audited Financial Statements" is defined in Section 3.3.1.

        "Business" means the businesses conducted by the Company and proposed to
be conducted by the Company.

        "Business Day" means any weekday other than a weekday on which banks in
Germany are authorized or required to be closed.

        "Buyer" is defined in the Preamble.

        "Cap" is defined in Section 11.1.2.

        "Cash Payment" is defined in Section 2.6.6.

        "Change of Control" shall mean an event in which (i) ViaCell consummates
a merger or consolidation with any other entity, other than a merger or
consolidation which would result in the voting securities of ViaCell outstanding
immediately prior thereto to represent (either by remaining outstanding or by
being converted into voting securities of the surviving entity) more than 50% of
the combined voting power of the voting securities of ViaCell or such surviving
entity outstanding immediately after such merger or consolidation; (ii) ViaCell
consummates the sale or disposition of all or substantially all of its assets;
(iii) more than fifty percent (50%) of the outstanding capital stock of ViaCell
is transferred to a third party in a single transaction or series of related
transactions; (iv) ViaCell consummates a liquidation or other liquidating sale;
or (v) ViaCell consummates a merger or consolidation in which it is not the
surviving company and which is not otherwise described in clause (i).

        "Closing" is defined in Section 2.5.

        "Closing Date" is defined in Section 2.5.

        "Closing Date Net Working Capital Statement" means the written
statement, prepared in accordance with GAAP and the methodology agreed upon by
the Buyer and the Company as set

                                      -2-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

forth on Exhibit G hereto setting forth in reasonable detail the Company's
determination of Net Working Capital as of the Closing Date.

        "Code" means the U.S. Internal Revenue Code of 1986.

        "Common Shares" is defined in the Preamble.

        "Common Sellers" are the holders of 100% of the Common Shares, as set
forth on Schedule 2 to this Agreement.

        "Company" is defined in the Preamble.

        "Company's Knowledge" means the actual knowledge of the Company,
including the officers of the Company and such other employees of the Company
who would be reasonably expected to have knowledge of the matter in question.

        "Company Option Holder" means a Person entitled to receive a Company
Option as set forth on Schedule 4 hereto.

        "Company Options" means the options to purchase any capital stock of the
Company pursuant to the Company's stock option plan.

        "Company Plans" is defined in Section 3.15.

        "Company Technology" is defined in Section 3.10.1.

        "Compensation" means, with respect to any Person, all salaries,
compensation, remuneration, bonuses or benefits of any kind or character
whatever (including issuances or grants of Equity Interests), made directly or
indirectly by the Company to such Person or Affiliates of such Person.

        "Contemplated Transactions" means, collectively, the transactions
contemplated by this Agreement, including (a) the sale and purchase of the
Shares, and (b) the execution, delivery and performance of the Ancillary
Agreements.

        "Contingent Common Stock" is defined in Section 2.3.1.

        "Contingent Shares" is defined in Section 2.3.

        "Contracts" is defined in Section 3.9.

        "Contractual Obligation" means, with respect to any Person, any
contract, agreement, deed, mortgage, lease, license, commitment, promise,
undertaking, arrangement or understanding, whether written or oral and whether
express or implied, or other document or instrument (including any document or
instrument evidencing or otherwise relating to any Debt) to which or by which
such Person is a party or otherwise subject or bound or to which or by which any
property, business, operation or right of such Person is subject or bound.

                                      -3-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

        "Debt" means, with respect to any Person, all obligations (including all
obligations in respect of principal, accrued interest, penalties, fees and
premiums) of such Person (a) for borrowed money (including overdraft
facilities), (b) evidenced by notes, bonds, debentures or similar Contractual
Obligations, (c) for the deferred purchase price of property, goods or services
(other than trade payables or accruals incurred in the Ordinary Course of
Business), (d) under capital leases (in accordance with GAAP), (e) in respect of
letters of credit and bankers' acceptances, (f) for Contractual Obligations
relating to interest rate protection, swap agreements and collar agreements and
(g) in the nature of Guarantees of the obligations described in clauses (a)
through (f) above of any other Person.

        "Dispute" is defined in Section 12.12.1.

        "Encumbrance" means any charge, claim, community or other marital
property interest, condition, equitable interest, lien, license, option, pledge,
security interest, mortgage, right of way, easement, encroachment, servitude,
right of first offer or first refusal, buy/sell agreement and any other
restriction or covenant with respect to, or condition governing the use,
construction, voting (in the case of any security or equity interest), transfer,
receipt of income or exercise of any other attribute of ownership.

        "Enforceable" means, with respect to any Contractual Obligation stated
to be Enforceable by or against any Person, that such Contractual Obligation is
a legal, valid and binding obligation of such Person enforceable by or against
such Person in accordance with its terms, except to the extent that enforcement
of the rights and remedies created thereby is subject to bankruptcy, insolvency,
reorganization, moratorium and other similar laws of general application
affecting the rights and remedies of creditors and to general principles of
equity (regardless of whether enforceability is considered in a proceeding in
equity or at law).

        "Environmental Laws" means any Legal Requirement relating to (a)
releases or threatened releases of Hazardous Substances, (b) pollution or
protection of public health or the environment or worker safety or health or (c)
the manufacture, handling, transport, use, treatment, storage, or disposal of
Hazardous Substances.

        "Equity Interests" means (a) any capital stock, share, partnership or
membership interest, unit of participation or other similar interest (however
designated) in any Person and (b) any option, warrant, purchase right,
conversion right, exchange rights or other Contractual Obligation which would
entitle any Person to acquire any such interest in such Person or otherwise
entitle any Person to share in the equity, profit, earnings, losses or gains of
such Person (including stock appreciation, phantom stock, profit participation
or other similar rights).

        "Escrow Agent" is defined in Section 2.2.

        "Escrow Agreement" is defined in Section 2.2.

        "Escrow Proportionate Share" is defined in Section 2.2.

        "Escrowed Common Stock" is defined in Section 2.2.1.

        "Escrowed Shares" is defined in Section 2.2.

                                      -4-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

        "Facilities" means any buildings, plants, improvements or structures
located on the Real Property.

        "FDA" shall mean the United States Food and Drug Administration.

        "Financial Statements" is defined in Section 3.3.1.

        "Financing" means the Series J financing of ViaCell, as described in
Section 8.11 of this Agreement, which is a condition to the closing of the
Contemplated Transactions.

        "GAAP" means, in the case of ViaCell, generally accepted accounting
principles in the United States, or, in the case of the Company, the German
equivalent ("Grundsatze ordnungsgema(beta)er Buchfuhrung"), in each case as in
effect from time to time.

        "Government Order" means any order, writ, judgment, injunction, decree,
stipulation, ruling, determination or award entered by or with any Governmental
Authority.

        "Governmental Authority" means any United States federal, state or local
or any foreign government, or political subdivision thereof, or any
multinational organization or authority or any authority, agency or commission
entitled to exercise any administrative, executive, judicial, legislative,
police, regulatory or taxing authority or power, any court or tribunal (or any
department, bureau or division thereof), or any arbitrator or arbitral body.

        "Guarantee" means, with respect to any Person, (a) any guarantee of the
payment or performance of, or any contingent obligation in respect of, any Debt
or other Liability of any other Person, (b) any other arrangement whereby credit
is extended to any obligor (other than such Person) on the basis of any promise
or undertaking of such Person (i) to pay the Debt or other Liability of such
obligor, (ii) to purchase any obligation owed by such obligor, (iii) to purchase
or lease assets under circumstances that are designed to enable such obligor to
discharge one or more of its obligations or (iv) to maintain the capital,
working capital, solvency or general financial condition of such obligor and (c)
any liability as a general partner of a partnership or as a venturer in a joint
venture in respect of Debt or other obligations of such partnership or venture.

        "Hazardous Substance" is defined in Section 3.20.

        "Indemnity Claim" means a claim for indemnity under Section 11.

        "Indemnified Party" means, with respect to any Indemnity Claim, the
party asserting such claim under Section 11.1.

        "Indemnifying Party" means, with respect to any Indemnity Claims, the
party against whom such claim is asserted.

        "Initial Budget" means the projected budget for the business of the
Company following the Closing (including provisions for the continuation of the
Company's research and development operations and the launching of European cord
blood banking), attached hereto as Exhibit F,

                                      -5-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

which will take effect on the Closing Date, and will be revised from time to
time in ViaCell's reasonable business judgment.

         "Insurance Policies" is defined in Section 3.11.

         "Intellectual Property" means the entire right, title and interest in
and to all proprietary rights of every kind and nature, including all rights and
interests pertaining to or deriving from:

                  (a) patents, copyrights, mask work rights, technology,
         know-how, processes, trade secrets, algorithms, inventions, works,
         proprietary data, databases, formulae, research and development data
         and computer software or firmware;

                  (b) trademarks, trade names, service marks, service names,
         brands, trade dress and logos, and the goodwill and activities
         associated therewith;

                  (c) domain names, rights of privacy and publicity, moral
         rights, and proprietary rights of any kind or nature, however
         denominated, throughout the world in all media now known or hereafter
         created;

                  (d) any and all registrations, applications, recordings,
         licenses, common-law rights and Contractual Obligations relating to any
         of the foregoing; and

                  (e) all Actions and rights to sue at law or in equity for any
         past or future infringement or other impairment of any of the
         foregoing, including the right to receive all proceeds and damages
         therefrom, and all rights to obtain renewals, continuations, divisions
         or other extensions of legal protections pertaining thereto.

         "Legal Requirement" means any United States federal, state or local or
foreign law, statute, standard, ordinance, code, rule, regulation, resolution or
promulgation, or any Governmental Order, or any license, franchise, permit or
similar right granted under any of the foregoing, or any similar provision
having the force or effect of law.

         "Liability" means, with respect to any Person, any liability or
obligation of such Person whether known or unknown, whether asserted or
unasserted, whether determined, determinable or otherwise, whether absolute or
contingent, whether accrued or unaccrued, whether liquidated or unliquidated,
whether incurred or consequential, whether due or to become due and whether or
not required under GAAP to be accrued on the financial statements of such
Person.

         "Licenses" is defined in Section 3.10.5.

         "Losses" is defined in Section 11.1.1.

         "MSAB" means Medical and Scientific Advisory Board of ViaCell, as
further described in Section 7.5.

         "Material Adverse Effect" means any change in, or effect on, the
business, operations, assets, prospects or condition (financial or otherwise) of
a Person which, when considered either individually or in the aggregate together
with all other adverse changes or effects with respect to

                                      -6-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

which such phrase is used in this Agreement, is, or is reasonably likely to be,
materially adverse to the business, operations, assets, prospects or condition
(financial or otherwise) of such Person and its Subsidiaries, taken as a whole,
other than changes, effects or circumstances (i) that are the result of factors
generally affecting the industry in which the Person operates or (ii) that are
attributable to the performance of this Agreement or the consummation of the
Contemplated Transactions.

         "Members of the Immediate Family" means, with respect to any
individual, (a) such Person's spouse, (b) each parent, brother, sister or child
of such Person or such Person's spouse, (c) the spouse of any Person described
in clause (b) above, (d) each child of any Person described in clauses (a), (b)
or (c) above, (e) each trust created solely for the benefit of one or more of
the Persons described in clauses (a) through (d) above and (f) each custodian or
guardian of any property of one or more of the Persons described in clauses (a)
through (e) above in his capacity as such custodian or guardian.

         "Milestones" is defined in Section 2.4.

         "Milestone Payments" is defined in Section 2.4.

         "Monthly Financials" means the monthly unaudited financial statements
of the Company in the form customarily prepared by management for internal use
for each complete month after the Most Recent Balance Sheet Date.

         "Most Recent Balance Sheet Date" is defined in Section 3.3.1.

         "MPM Sellers" means, collectively, MPM Founders LLC, MPM BioVentures II
QP L.P., MPM BioVentures GmbH & Co. Parallel-Beteiligungs KG, MPM BioVentures II
L.P., and MPM Asset Management Investors 2001 BVII LLC.

         "Net Working Capital" means current assets minus current liabilities,
determined in accordance with GAAP and the methodology described on Exhibit G.

         "Net Working Capital Shortfall" is defined in Section 2.7.

         "Net Working Capital Target" means Net Working Capital of the Company
of at least $5.2 million.

         "Note Escrow Agreement" means the escrow agreement executed by ViaCell
in conjunction with the Notes pursuant to which ViaCell will deposit $4.2
million with an escrow agent for the term of the Notes.

         "Notes" is defined in Section 2.1.1.

         "Ordinary Course of Business" means an action taken by any Person in
the ordinary course of such Person's business which is consistent with the past
customs and practices of such Person (including past practice with respect to
quantity, amount, magnitude and frequency, standard employment and payroll
policies and past practice with respect to management of working

                                      -7-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

capital) which is taken in the ordinary course of the normal day-to-day
operations of such Person.

         "Organizational Documents" means, with respect to any Person (other
than an individual), (a) the certificate or articles of incorporation or
organization and any joint venture, limited liability company, operating or
partnership agreement and other similar documents adopted or filed in connection
with the creation, formation or organization of such Person and (b) all by-laws,
voting agreements and similar documents, instruments or agreements relating to
the organization or governance of such Person, in each case, as amended or
supplemented.

         "OSHA" is defined in Section 5.8.

         "Percentage Ownership" means the percentage ownership of each Seller as
set forth on Schedule 6 hereto.

         "Person" means any individual or corporation, association, partnership,
limited liability company, joint venture, joint stock or other company, business
trust, trust, organization, Governmental Authority or other entity of any kind.

         "Phase I Study" shall have the meaning ascribed to it in Title 21 of
the United States Code of Federal Regulations, Section 312.21(a) and shall also
be conducted following Good Clinical Practice (GCP) Guidelines established by
the International Conference on Harmonisation of Technical Requirements for
Registration of Pharmaceuticals for Human Use (ICH, Guideline E6, GCP:
Consolidated Guideline, 1 May 1996).

         "Phase II Study" shall mean a well-controlled clinical study that also
has the meaning ascribed to it in Title 21 of the United States Code of Federal
Regulations, Section 312.21(b) and shall also be conducted following GCP
Guidelines established by the ICH (Guideline E6, GCP: Consolidated Guideline, 1
May 1996).

         "Phase III Study" shall mean a well-controlled clinical study that also
has the meaning ascribed to it in Title 21 of the United States Code of Federal
Regulations, Section 312.21(c) and shall also be conducted following GCP
Guidelines established by the ICH (Guideline E6, GCP: Consolidated Guideline, 1
May 1996).

         "Plan Sponsor" is defined in Section 5.17.

         "Plans" is defined in Section 5.17.

         "Predecessor" means, with respect to the Company (a) any Person that
has ever merged with or into the Company, (b) any Person a majority of whose
capital stock (or similar outstanding ownership interests) or Equity Interests
has ever been acquired by the Company, (c) any Person all or substantially all
of whose assets has ever been acquired by the Company, and (d) any prior names
of the Company or any Person described in clauses (a) through (c).

         "Product" or "Products" shall mean each product manufactured, sold,
leased, licensed, delivered or installed by the Company, including any USSC
Company Product.

                                      -8-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

        "Proprietary Rights" is defined in Section 5.14.

        "Purchase Price Deduction" is defined in Section 2.7.

        "Qualified Public Offering" shall mean a firm commitment underwritten
public offering of the common stock of ViaCell at a price per share of at least
$9.70 (as appropriately adjusted to reflect any conversion of preferred stock
into common stock, any stock splits or combinations, or any declaration of
dividends or distributions or other similar recapitalization) in which the net
proceeds received by ViaCell equal or exceed $50 million.

        "Real Property" is defined in Section 3.19.1.

        "Real Property Leases" is defined in Section 3.19.1.

        "Representative" means, with respect to any Person, any director,
officer, employee, agent, consultant, advisor, or other representative of such
Person, including legal counsel, accountants, and financial advisors.

        "Securities Act" means the Securities Act of 1933.

        "Seller" and "Sellers" are defined in the Preamble.

        "Sellers' Representative" means Dr. Stephan Wnendt, as representative
for the Sellers.

        "Series A Shares" is defined in the Preamble.

        "Series A Sellers" means the holders of 100% of the Series A Shares as
set forth on Schedule 1 to this Agreement.

        "Series I Agreements" means (i) the Fourth Amended and Restated
Stockholders Agreement of ViaCell, (ii) the Fourth Amended and Restated
Registration Rights Agreement of ViaCell, and (iii) the Third Amended and
Restated Investors' Rights Agreement of ViaCell, as amended from time to time
including in connection with the Financing attached hereto as Exhibit J.

        "Series I Stock" is defined in Section 2.1.1.

        "Shares" is defined in the recitals to this Agreement.

        "Subsidiary" means, with respect to any specified person, any other
Person of which such specified Person will, at the time, directly or indirectly
through one or more Subsidiaries, (a) own at least 50% of the outstanding
capital stock (or other shares of beneficial interest) entitled to vote
generally, (b) hold at least 50% of the partnership, limited liability company,
joint venture or similar interests or (c) be a general partner, managing member
or joint venturer.

        "Tax" or "Taxes" means (a) any and all federal, state, local, or foreign
income, gross receipts, license, payroll, employment, excise, severance, stamp,
occupation, premium, windfall profits, environmental, customs duties, capital
stock, franchise, profits, withholding, social security (or similar, including
FICA), unemployment, disability, real property, personal property,

                                      -9-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

sales, use, transfer, registration, value added, alternative or add-on minimum,
estimated, or other tax of any kind or any charge of any kind in the nature of
(or similar to) taxes whatsoever, including any interest, penalty, or addition
thereto, whether disputed or not and (b) any liability for the payment of any
amounts of the type described in clause (a) of this definition as a result of
being a member of an affiliated, consolidated, combined or unitary group for any
period, as a result of any tax sharing or tax allocation agreement, arrangement
or understanding, or as a result of being liable for another person's taxes as a
transferee or successor, by contract or otherwise.

         "Tax Return" means any return, declaration, report, claim for refund or
information return or statement relating to Taxes, including any schedule or
attachment thereto, and including any amendment thereof.

         "Technology" means all inventions, works, discoveries, innovations,
know-how, information (including ideas, research and development, know-how,
formulas, compositions, processes and techniques, data, designs, drawings,
specifications, customer and supplier lists, pricing and cost information,
business and marketing plans and proposals, documentation and manuals), computer
software, firmware, computer hardware, integrated circuits and integrated
circuit masks, electronic, electrical and mechanical equipment and all other
forms of technology, including improvements, modifications, works in process,
derivatives or changes, whether tangible or intangible, embodied in any form,
whether or not protectible or protected by patent, copyright, mask work right,
trade secret law or otherwise, and all documents and other materials recording
any of the foregoing.

         "Termination Date" is defined in Section 10.1.

         "Third Party Claim" is defined in Section 11.3.1.

         "Total Purchase Price" is defined in Section 2.1.

         "Transaction Expenses" is defined in Section 6.2.

         "Transaction Fee Proportionate Share" is defined in Section 2.6.6.

         "Transaction Fee Statement" means the written statement of Transaction
Expenses of the Company and the Sellers as set forth on Exhibit L, to be
delivered by the Company in connection with the Closing.

         "Unaudited Financial Statements" is defined in Section 3.3.1.

         "U.S. Sellers" means, collectively, the MPM Sellers (except for MPM
BioVentures GmbH & Co. Parallel-Beteiligungs KG) and Phillip Coelho.

         "USSC" means Unrestricted Somatic Stem Cell.

         "USSC Company Product" is defined in Section 2.4.

         "ViaCell Balance Sheet" is defined in Section 5.5.

                                      -10-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

        "ViaCell Balance Sheet Date" is defined in Section 5.5.

        "ViaCell Common Stock" means shares of the common stock, par value $0.01
per share, of ViaCell.

        "ViaCell Financial Statements" is defined in Section 5.5.

        "ViaCell Indemnified Person" is defined in Section 11.1.1.

        "ViaCell Option Plan" is defined in Section 7.2.

        "ViaCell Permits" is defined in Section 5.8.

        "ViaCell Subsidiary" is defined in Section 5.2.

Except as otherwise explicitly specified to the contrary, (a) references to a
Section, Article, Exhibit or Schedule means a Section or Article of, or Schedule
or Exhibit to this Agreement, unless another agreement is specified, (b) the
word "including" will be construed as "including without limitation," (c)
references to a particular statute or regulation include all rules and
regulations thereunder and any predecessor or successor statute, rules or
regulation, in each case as amended or otherwise modified from time to time, (d)
words in the singular or plural form include the plural and singular form,
respectively and (e) references to a particular Person include such Person's
successors and assigns to the extent not prohibited by this Agreement.

         2. PURCHASE AND SALE OF SHARES.

                  2.1. Purchase and Sale of Shares. Upon the terms and
         conditions set forth herein, each Seller hereby sells, conveys,
         transfers, assigns, grants and delivers to ViaCell, and ViaCell hereby
         purchases, acquires and accepts from each Seller, subject to the terms
         and conditions of the Company's Articles of Association, all right,
         title, and interest in and to the Shares held by such Seller, free and
         clear of all liabilities, obligations, pledges, security interests,
         liens, contractual commitments, claims, defenses, setoffs, equities,
         encumbrances or charges in consideration of the issuance of the Notes
         and the number of shares of ViaCell capital stock as specified below
         (including the shares described in Sections 2.2 and 2.3 below, but not
         Section 2.4, the "Total Purchase Price").

                  2.1.1. Series A Shares. At the Closing, the Series A Sellers
         will sell, assign and transfer to ViaCell, and ViaCell will purchase
         and acquire from the Series A Sellers, 100% of the outstanding Series A
         Shares. Each Series A Seller will sell to ViaCell all of the Series A
         Shares owned by such Series A Seller, the specific number of which is
         set forth opposite each Series A Seller's name on Schedule 1. The
         initial consideration for the sale and transfer of the Series A Shares
         will consist of (i) promissory notes issued by ViaCell in the original
         aggregate principal amount of $14 million in the form attached hereto
         as Exhibit A in favor of the Series A Sellers in the denominations set
         forth opposite each Series A Seller's name on Schedule 1 (the "Notes"),
         and (ii) such number of shares of Series I Convertible Preferred Stock
         of ViaCell, par value $0.01 per share (the "Series I Stock"), as set
         forth opposite each Series A Seller's name on Schedule 1.

                                      -11-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

                  2.1.2. Common Shares. At the Closing, the Common Sellers will
         sell, assign and transfer to ViaCell, and ViaCell will purchase and
         acquire from the Common Sellers, 100% of the outstanding Common Shares.
         Each Common Seller will sell to ViaCell all of the Common Shares owned
         by such Common Seller, the specific number of which is set forth
         opposite such Common Seller's name on Schedule 2. The initial
         consideration for the sale and transfer of the Common Shares will
         consist of the number of shares of Series I Stock set forth opposite
         each Common Seller's name on Schedule 2.

         2.2. Escrowed Shares. As additional initial consideration, on the
Closing Date, ViaCell will issue 241,481 shares of Series I Stock (as such
number of shares may be reduced pursuant to Section 2.7 and, after the Closing,
pursuant to Section 11.5, the "Escrowed Shares") and these shares will be
deposited in escrow with Dr. Norbert Zimmermann, as escrow agent (the "Escrow
Agent") for the benefit of the Sellers (other than the MPM Sellers) pursuant to
the Escrow Agreement in the form attached hereto as Exhibit B (the "Escrow
Agreement"). All Escrowed Shares held by the Escrow Agent will be released to
the Sellers (other than the MPM Sellers) pro rata based on the proportionate
share of each Seller (other than the MPM Sellers) set forth on Schedule 3 hereto
(the "Escrow Proportionate Share") (and also as set forth in Exhibit 1 to the
Escrow Agreement), in accordance with the following provisions.

                  2.2.1. Release upon a Qualified Public Offering. Unless sooner
         released pursuant to Section 2.2.2 or returned to ViaCell pursuant to
         Section 2.2.3, the Escrow Agent will release the Escrowed Shares
         immediately following the closing of a Qualified Public Offering that
         occurs prior to the third anniversary of the Closing Date. The released
         Escrowed Shares will be exchanged by the Escrow Agent for the number of
         shares of ViaCell Common Stock into which the Escrowed Shares are then
         convertible (the "Escrowed Common Stock") within five (5) Business Days
         of the closing of the Qualified Public Offering. The Escrow Agent will
         then deliver the Escrowed Common Stock to each Seller (other than the
         MPM Sellers) in accordance with the terms of the Escrow Agreement
         (except for such Escrowed Shares that are subject to a disputed
         indemnification claim pursuant to the terms of the Escrow Agreement)
         and the Escrow Agreement shall thereupon terminate in accordance with
         its terms.

                  2.2.2. Release upon a Change of Control. Unless sooner
         released pursuant to Section 2.2.1 or returned to ViaCell pursuant to
         Section 2.2.3, the Escrow Agent will release and deliver the Escrowed
         Shares to each Seller (other than the MPM Sellers) in accordance with
         the terms of the Escrow Agreement upon the closing of a Change of
         Control as defined in clauses (i), (ii), (iii) and (iv) of the "Change
         of Control" definition set forth herein (but excluding an event
         described in clause (iv) which occurs solely in connection with a
         corporate reorganization), but not upon the closing of an event
         described in clause (v) of such definition) that occurs prior to the
         third anniversary of the Closing Date. In the event that the holders of
         Series I Stock are entitled to receive cash, securities or other
         property in exchange for the shares of Series I Stock pursuant to such
         Change of Control, the Escrow Agent will exchange the Escrowed Shares
         for such equivalent cash, securities or property to which the holder of
         the Escrowed Shares is entitled pursuant to such Change of Control and
         shall deliver the same to each Seller (other than the MPM Sellers) in
         accordance with the terms of the Escrow Agreement

                                      -12-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

         (except for such Escrowed Shares that are subject to a disputed
         indemnification claim pursuant to the terms of the Escrow Agreement)
         and the Escrow Agreement shall thereupon terminate in accordance with
         its terms.

                  2.2.3. Termination. Unless earlier terminated pursuant to
         Section 2.2.1 or 2.2.2, the escrow described in this Section will
         terminate on the third anniversary of the Closing Date, and the Escrow
         Agent will return the Escrowed Shares to ViaCell in accordance with the
         terms of the Escrow Agreement, the Escrow Agreement shall thereupon
         terminate in accordance with its terms, and the Sellers will have no
         further rights in respect of the Escrowed Shares.

         2.3. Contingent Shares. As additional initial consideration, ViaCell
will issue 289,256 shares of Series I Stock to the MPM Sellers (as such number
of shares may be reduced pursuant to Section 2.7 and, after the Closing,
pursuant to Section 11.5, and increased pursuant to the last sentence of Section
2.3.2, the "Contingent Shares") pro rata as set forth on Schedule 5 hereto in
accordance with the following provisions.

                  2.3.1. Issue of Contingent Shares upon a Qualified Public
         Offering. Unless sooner issued pursuant to Section 2.3.2, ViaCell will
         issue the Contingent Shares to the MPM Sellers immediately following
         the closing of a Qualified Public Offering that occurs prior to the
         third anniversary of the Closing Date. The issued Contingent Shares
         will be exchanged by ViaCell for the number of shares of ViaCell Common
         Stock into which the Contingent Shares are then convertible (the
         "Contingent Common Stock") within five (5) Business Days of the closing
         of the Qualified Public Offering (except for such Contingent Shares
         that are subject to a disputed indemnification claim).

                  2.3.2. Issue of Contingent Shares upon a Change of Control.
         Unless sooner issued pursuant to Section 2.3.1, ViaCell will issue the
         Contingent Shares to the MPM Sellers promptly upon the closing of a
         Change of Control as defined in clauses (i), (ii), (iii) and (iv) of
         the "Change of Control" definition as set forth herein (but excluding
         an event described in clause (iv) which occurs solely in connection
         with a corporate reorganization) but not upon closing of an event as
         described in clause (v) of such definition) that occurs prior to the
         third anniversary of the Closing Date. In the event that the holders of
         Series I Stock are entitled to receive cash, securities or other
         property in exchange for the shares of Series I Stock pursuant to such
         Change of Control, ViaCell will, in lieu of the Contingent Shares,
         issue such equivalent cash, securities or property to which the holder
         of the Contingent Shares is entitled (except for such Contingent Shares
         that are subject to a disputed indemnification claim) pursuant to such
         Change of Control, and shall deliver the same to each MPM Seller. In
         addition, in the event that the Contingent Shares are issued pursuant
         to this Section 2.3.2, ViaCell will issue to the MPM Sellers an
         additional number of shares of Series I Stock equal to eight percent
         (8%) of the initial number of such Contingent Shares compounded
         annually from the Closing Date to the date of such issuance.

                  2.3.3. Termination of Obligation to Issue Contingent Shares.
         Unless earlier delivered pursuant to Section 2.3.1 or 2.3.2, the
         obligation of ViaCell to issue the

                                      -13-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

         Contingent Shares to the MPM Sellers will terminate on the third
         anniversary of the Closing Date.

         2.4. Milestone Payments. As additional consideration for the Shares,
ViaCell will make the following payments or issue the following additional
shares of Series I Stock (the "Milestone Payments") to the Sellers within thirty
(30) days following the achievement of the milestones described below (the
"Milestones") relating to USSC product candidates in development by the Company
prior to the Closing Date (each, a "USSC Company Product"). Such Milestone
Payments will be paid to each Seller pro rata based on each Seller's Percentage
Ownership as set forth on Schedule 6 hereto in cash, or, at the election of each
Seller, in shares of Series I Stock, which shares are deemed for purposes of
this Section to have a value of $8.00 per share; provided that, if ViaCell shall
have completed an initial public offering prior to the time a Milestone Payment
is due to the Sellers and a Seller elects to receive shares instead of cash, the
Milestone Payment will be paid in shares of ViaCell Common Stock in lieu of the
issuance of Series I Stock, based on the then current market price of such stock
(calculated as the average closing price of the ViaCell Common Stock on the
principal market on which it is then traded for the ten (10) days preceding and
the ten (10) days following the achievement of the Milestone). In any event, no
Milestone Payment will be paid more than once, regardless of the number of times
such Milestone is achieved.

         2.4.1. Phase II Milestone Payments.

                  (a) $3.0 million, upon the receipt by ViaCell or any ViaCell
         Subsidiary (including the Company) by December 31, 2006 of final,
         audited clinical trial data that are determined to be positive outcome
         data for a cardiac indication from a well-controlled Phase II Study
         regarding a USSC Company Product (the date of such determination being
         deemed to be the date of achievement of the Milestone, provided that
         the Milestone shall be deemed to have been met if the data is received
         before December 31, 2006, regardless of the date of such
         determination).

                  (b) $3.0 million, upon the receipt by ViaCell or any ViaCell
         Subsidiary (including the Company) by June 30, 2007 of final, audited
         clinical trial data that are determined to be positive outcome data for
         a non-cardiac indication from a well-controlled Phase II Study
         regarding a USSC Company Product (the date of such determination being
         deemed to be the date of achievement of the Milestone, provided that
         the Milestone shall be deemed to have been met if the data is received
         before June 30, 2007, regardless of the date of such determination).

For purposes of this Section, the term "positive outcome data" shall mean data
obtained from a well-controlled Phase II Study, which demonstrate a reasonably
acceptable safety profile and which provide reasonable evidence of clinical
efficacy, and which support either (i) the immediate submission of a marketing
authorization application, or (ii) the initiation of a Phase III Study following
consultation and agreement with applicable regulatory authorities.

         2.4.2. Product Approval Milestone Payments.

                                      -14-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

                  (a) $3.0 million, upon the receipt by ViaCell or any ViaCell
         Subsidiary (including the Company) of all required regulatory approvals
         (including pricing and reimbursement approval, if required) by December
         31, 2011 to market a USSC Company Product for a cardiac indication in
         both the United States and the European Union.

                  (b) $3.0 million, upon the receipt by ViaCell or any ViaCell
         Subsidiary (including the Company) of all required regulatory approvals
         (including pricing and reimbursement approval, if required) by December
         31, 2012 to market a USSC Company Product for a non-cardiac indication
         in both the United States and the European Union.

         2.5. The Closing. The closing (the "Closing") with respect to the
Contemplated Transactions will take place at the offices of Ropes & Gray LLP,
One International Place, Boston, Massachusetts, on _____________, 2003 (the
"Closing Date") or at such other place and on such other date as the parties may
agree in writing.

         2.6. Closing Deliveries.

                  2.6.1. Series A Shares. At the Closing (i) ViaCell shall
         deliver to the Series A Sellers (a) the Notes, and (b) a certificate or
         certificates representing the number of shares of Series I Stock set
         forth opposite each Series A Seller's name on Schedule 1, and (ii) the
         Series A Sellers will assign to ViaCell the number of Series A Shares
         set forth opposite each Series A Seller's name on Schedule 1, in a form
         of Assignment attached hereto as Exhibit H (the "Assignment") and shall
         deliver to ViaCell the Assignment.

                  2.6.2. Common Shares. At the Closing (i) ViaCell shall deliver
         to each Common Seller a certificate for the number of shares of Series
         I Stock set forth opposite each Common Seller's name on Schedule 2, and
         (ii) each Common Seller will assign to ViaCell the number of Common
         Shares set forth opposite each Common Seller's name on Schedule 2 in a
         form of Assignment attached hereto as Exhibit H and shall deliver to
         ViaCell the Assignment.

                  2.6.3. Series I Agreements and Legends. The Sellers will, at
         or prior to the Closing, execute and become party to all Series I
         Agreements or amendments thereto, and each share of Series I Stock
         received by the Sellers will bear restrictive legends as described in
         Section 4.5 hereof.

                  2.6.4. Escrowed Shares. At the Closing, ViaCell shall deliver
         the Escrowed Shares to the Escrow Agent as specified in Section 2.2.

                  2.6.5. Share Register. At the Closing and subject to the
         delivery of the forms of Assignment in accordance with Sections 2.6.1
         and 2.6.2 hereunder, the Company shall deliver to ViaCell an updated
         excerpt of the share register of the Company stating that ViaCell is
         the holder of all Shares of the Company.

                  2.6.6. Cash Transfer. At the Closing, ViaCell will deliver
         cash in the amount set forth in the Transaction Fee Statement (the
         "Cash Payment") to the Company for the

                                      -15-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

                  benefit of the Sellers pro rata based on each Seller's
                  Percentage Ownership as set forth on Schedule 6 hereto (the
                  "Transaction Fee Proportionate Share"). The total amount of
                  the Cash Payment will be subtracted from the Total Purchase
                  Price as set forth in Section 2.7. Following the Closing, the
                  Company will use the Cash Payment to pay the Transaction
                  Expenses set forth on the Transaction Fee Statement, including
                  brokers' fees.

                  2.7. Purchase Price Adjustment. If the Net Working Capital of
         the Company (as set forth on the Closing Date Net Working Capital
         Statement) is less than the Net Working Capital Target, then the Buyer
         will subtract an amount equal to such shortfall (the "Net Working
         Capital Shortfall") and the total amount of Transaction Expenses set
         forth on the Transaction Fee Statement (collectively, the "Purchase
         Price Deduction") from the Total Purchase Price payable to the Sellers.
         The Purchase Price Deduction will be subtracted from the Total Purchase
         Price in the following manner, based on the value of the Series I
         Shares at $8.00 per share:

                           (i) 18.75% of the total Purchase Price Deduction will
                  be subtracted pro rata from (a) the total amount of Escrowed
                  Shares held by the Escrow Agent pursuant to Section 2.2 and
                  (b) the total amount of Contingent Shares; and

                           (ii) 81.25% of the total Purchase Price Deduction
                  will be subtracted from total amount of shares of Series I
                  Stock paid to the Series A Sellers and the Common Sellers
                  pursuant to Section 2.1, of which 48.55% of such shares will
                  be subtracted from the number of shares issuable to the Series
                  A Sellers and the remainder of such shares subtracted from the
                  number of shares otherwise issuable to the Common Sellers pro
                  rata in accordance with Schedule 3 hereto.

                  Schedules 1, 2, 3, 4 and 5 will reflect the number of shares
         of Series I Stock to be issued pursuant to this Agreement both before
         and after the adjustments required by this Section 2.7.

                  2.8. Remainder. Any amounts remaining from the cash
         transferred to the Company pursuant to Section 2.6.6 after payment in
         full or settlement of the Transaction Expenses as set forth in the
         Transaction Fee Statement, shall be distributed to the Sellers pro rata
         based on each Seller's Transaction Fee Proportionate Share.

         3. REPRESENTATIONS AND WARRANTIES RELATING TO THE COMPANY.

         The Company hereby makes the following representations and warranties
to ViaCell, each of which is complete and correct as of the execution of this
Agreement and on and as of the Closing Date:

                  3.1. Capitalization and Ownership. The Shares constitute all
         of the issued and outstanding shares of capital stock of the Company
         and, except as set forth in Schedule 3.1, no person or entity has any
         other right, title or interest in the Company or any profits, earnings,
         gains or losses with respect thereto. All of such Shares are duly
         authorized, validly issued, fully paid and non-assessable and are owned
         of record by the Sellers in the respective amounts indicated next to
         each Sellers name on Schedule 1 and Schedule 2 hereto. No share

                                      -16-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

         certificates ("Aktienurkunde") and no interim shares certificates
         ("Zwischenscheine") have been issued for any of the Shares. Except as
         set forth in Schedule 3.1, there are no agreements, arrangements or
         commitments (other than this Agreement) to which the Company is a party
         or is otherwise bound (i) relating to the acquisition, exchange,
         conversion or disposition of any of the Shares or any other equity
         interest in the Company; (ii) under which the Company is or may be
         obligated to issue any equity interests in the Company or options to
         purchase equity interests in the Company; or (iii) relating to the
         repurchase or redemption of any of the Shares of the Company. There are
         no outstanding options, warrants or other rights to subscribe for or
         purchase any equity interest in the Company. All previously granted
         outstanding options of the Company have been exercised or cancelled.

                  3.2. Corporate Organization. The Company is a corporation duly
         and validly existing under the laws of Germany, with full power and
         authority under such laws, as amended from time to time, and its
         Articles of Association to own or lease its properties and to conduct
         its business in the manner and in the places where such properties are
         owned or leased or such business is currently conducted. The copy of
         the Company's Articles of Association, as amended to date and
         heretofore delivered to ViaCell's counsel, is complete and correct, and
         no amendment thereto is pending. The Company is duly qualified to do
         business under the laws of each jurisdiction in which its current
         business, or the ownership or leasing of its properties, requires such
         qualification. The Company has no Subsidiaries, and does not own any
         equity or other proprietary interest in any other corporation,
         partnership, joint venture or other entity of any nature whatsoever.
         None of the outstanding Shares was issued in violation of applicable
         securities laws.

                  3.3. Financial Statements.

                           3.3.1. Attached hereto as Schedule 3.3 are the
                  following financial statements: (i) the unaudited balance
                  sheet, income statement and statement of cash flows of the
                  Company at and for the period ended June 30, 2003 (the
                  "Unaudited Financial Statements"); and (ii) the audited
                  balance sheet, income statement and statement of cash flows of
                  the Company as of December 31, 2002 (the "Most Recent Balance
                  Sheet Date") (the "Audited Financial Statements" and, together
                  with the Unaudited Financial Statements, the "Financial
                  Statements"). The Financial Statements (i) are accurate and
                  complete in all material respects; (ii) were prepared in
                  accordance with GAAP consistently applied throughout the
                  periods indicated; (iii) are consistent with the books and
                  records of the Company; and (iv) fairly set forth the results
                  of operations and financial condition of the Company for the
                  periods, and as of the dates, indicated.

                           3.3.2. Except as set forth in Schedule 3.3, the
                  Company does not as of the date hereof have any liabilities or
                  obligations of any nature, whether absolute, accrued, known,
                  unknown, contingent or otherwise, except to the extent
                  disclosed in the Financial Statements or incurred in the
                  Ordinary Course of Business since June 30, 2003 or incurred
                  with ViaCell's consent. The Company pays its bills and
                  liabilities in the Ordinary Course of Business.

                                      -17-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

                  3.4. Absence of Certain Developments. Since June 30, 2003, the
         Business has been conducted in the Ordinary Course of Business and,
         except for the matters disclosed in Schedule 3.4:

                           (a) the Company has not (i) amended its
                  Organizational Documents, (ii) amended any term of its
                  outstanding Equity Interests or other securities or (iii)
                  issued, sold, granted, or otherwise disposed of, its Equity
                  Interests or other securities;

                           (b) the Company has not become liable in respect of
                  any Guarantee or has incurred, assumed or otherwise become
                  liable in respect of any Debt, except for borrowings in the
                  Ordinary Course of Business;

                           (c) the Company has not permitted any of its Assets
                  to become subject to an Encumbrance;

                           (d) the Company has not (i) made any declaration,
                  setting aside or payment of any dividend or other distribution
                  with respect to, or any repurchase, redemption or other
                  acquisition of, any of its capital stock or other Equity
                  Interests or (ii) entered into, or performed, any transaction
                  with, or for the benefit of, any Seller or any Affiliate of
                  any Seller (other than payments made to officers, directors
                  and employees in the Ordinary Course of Business);

                           (e) there has been no material loss, destruction,
                  damage or eminent domain taking (in each case, whether or not
                  insured) affecting the Business or any material Asset;

                           (f) the Company has not increased the Compensation
                  payable or paid, whether conditionally or otherwise, to (i)
                  any employee, consultant or agent other than in the Ordinary
                  Course of Business, (ii) any director or officer or (iii) any
                  Seller or any Affiliate of any Seller;

                           (g) the Company has not entered into any Contractual
                  Obligation other than in the Ordinary Course of Business,
                  providing for the employment or consultancy of any Person on a
                  full-time, part-time, consulting or other basis or otherwise
                  providing Compensation or other benefits to any officer,
                  director, employee or consultant;

                           (h) the Company has not made any change in its
                  methods of accounting or accounting practices (including with
                  respect to reserves);

                           (i) the Company has not made, changed or revoked any
                  material Tax election, elected or changed any method of
                  accounting for Tax purposes, settled any Action in respect of
                  Taxes or entered into any Contractual Obligation in respect of
                  Taxes with any Governmental Authority;

                           (j) the Company has not terminated or closed any
                  Facility, business or operation;

                           (k) the Company has not adopted any Company Plan or,
                  except in accordance with terms thereof as in effect on the
                  Most Recent Balance Sheet Date, increased any benefits under
                  any Company Plan;

                                      -18-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

                           (l) the Company has not written up or written down
                  any of its material Assets or revalued its inventory except as
                  within the Ordinary Course of Business and as required by law;

                           (m) the Company has not entered into any Contractual
                  Obligation to do any of the things referred to elsewhere in
                  this Section 3.4; and

                           (n) no event or circumstance has occurred which has
                  had, or is reasonably likely to have, a Material Adverse
                  Effect.

                  3.5. Powers and Authority. The Company has all requisite legal
         capacity, power and authority (including full corporate power and
         authority) to own and operate the assets of the Company and to carry on
         the Business. The execution, delivery and performance of this Agreement
         and each agreement, document and instrument to be executed and
         delivered pursuant to, or as contemplated by, this Agreement have been
         duly authorized by all necessary action of the Company and no other
         action on the part of the Company is required in connection therewith.
         The Company is not in violation of, and has not violated, any
         instrument, permit, decree, order, statute, ordinance or governmental
         regulation except for those violations which do not have a Material
         Adverse Effect. Except as set forth on Schedule 3.5, the Company has in
         force all governmental permits, licenses and authorizations necessary
         to conduct the Business.

                  3.6. No Breaches, Violations or Consents. Neither the
         execution and delivery of this Agreement nor the compliance with the
         terms and provisions of this Agreement (a) conflicts with or results in
         a breach of any of the terms, conditions or provisions of any contract
         or other instrument to which the Company is a party or by which the
         Company may be bound or constitutes a default thereunder; (b) results
         in the creation or imposition of any Encumbrance upon or gives to
         others any interest or rights in or with respect to any of the Shares
         or Assets; (c) violates any law, statute, or regulation of any
         Governmental Authority; or (d) otherwise impacts in any manner upon the
         rights of the Company under any of the Contracts, except as set forth
         on Schedule 3.6. No approval, consent, waiver, authorization or other
         order of, and no declaration, filing, registration, qualification or
         recording with, any Governmental Authority is required to be made by or
         on behalf of the Company in connection with the execution, delivery or
         performance of this Agreement and the transactions contemplated hereby.

                  3.7. Title to and Condition of the Assets. The Company has
         good and marketable title to the Assets and the Business owned by the
         Company free and clear of all Encumbrances except as set forth on
         Schedule 3.7. All of the tangible personal property used by the Company
         in connection with the operation of the Business is included among the
         Assets owned or leased by the Company unless specified in Schedule 3.7,
         and the tangible personal property used by the Company is in working
         condition sufficient to continue to operate the Business in the
         ordinary course.

                  3.8. No Claims or Litigation. There is no litigation,
         judicial, administrative or arbitral action, proceeding, governmental
         investigation or claim pending or, to the Company's Knowledge,
         threatened that questions the validity of this Agreement or any action
         taken or to

                                      -19-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

         be taken by the Sellers in connection with this Agreement or that
         relates to the Company, the Assets or the Business. There is no
         judgment, order, injunction, decree or award outstanding (whether
         rendered by a court, administrative agency or arbitrator), against the
         Company.

                  3.9. Contracts. The contracts listed on Schedule 3.9 (the
         "Contracts") consist of all contracts, agreements, or other
         arrangements of any nature, whether written or oral, to which the
         Company is a party and which are necessary for the conduct of the
         Business and which require, in the aggregate, annual payments in excess
         of $20,000, including without limitation all contracts with customers
         of the Company, all Contracts relating to the license of Intellectual
         Property, the grant of any funds to the Company or the terms of any
         employment or consulting arrangement with any individual. All such
         Contracts are, and immediately after giving effect to the Closing
         hereunder and the consummation of the Contemplated Transactions will
         be, in full force and effect, and neither the Company nor, to the
         Company's Knowledge, any other party thereto is in default nor has any
         event occurred which with notice or lapse of time would constitute a
         default in respect of any of the terms or provisions thereof. The
         Company has not breached any conditions of its grants of funding. There
         are no disputes or disagreements pending or, to the Company's
         Knowledge, threatened between the Company and any other party under any
         of the Contracts, and, to the Company's Knowledge, there is no basis
         for any such dispute or disagreement. True and correct copies of all of
         the Contracts have been delivered to counsel for ViaCell.

                  3.10. Intellectual Property.

                           3.10.1. The Company is the sole owner of and has the
                  right to use all technology as set forth in Schedule 3.10. The
                  "Company Technology" is all Technology used in connection with
                  the Business and any and all Intellectual Property in such
                  Technology.

                           3.10.2. Neither the Company nor any Predecessor (a)
                  has to the Company's Knowledge interfered with, infringed
                  upon, misappropriated, or otherwise come into conflict with
                  any Intellectual Property rights of third parties or (b) has
                  received any charge, complaint, claim, demand, or notice
                  alleging any such interference, infringement,
                  misappropriation, or violation (including any claim that a
                  Person must license or refrain from using any Intellectual
                  Property rights of any third party in connection with the
                  conduct of the Business or the use of the Company Technology).
                  To the Company's Knowledge, no third party has interfered
                  with, infringed upon, misappropriated, or otherwise come into
                  conflict with any Company Technology.

                           3.10.3. Schedule 3.10 identifies (a) all registered
                  Intellectual Property which has been issued to the Company or
                  is used by the Company in the Business, (b) each pending
                  application for registration which the Company has made with
                  respect to any Company Technology, (c) each Contractual
                  Obligation which the Company or any Seller has granted to any
                  third party with respect to any of (a) or (b) above and (d)
                  each Contractual Obligation which the Company or any Seller
                  has granted to any third party with respect to Company
                  Technology that is not included in (a) or (b) above. True,
                  accurate and complete copies of all such registrations,
                  applications and Contractual Obligations, in each case, as
                  amended, or otherwise modified and in effect, have been made
                  available to ViaCell, as well as true, accurate and complete
                  copies of all other written documentation

                                      -20-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

                  evidencing ownership and prosecution (if applicable) of each
                  such item. Schedule 3.10 also identifies each trade name,
                  trade dress and unregistered trademark or service mark used by
                  the Company or in connection with the Business or the Company
                  Technology.

                  3.10.4. With respect to each item of Company Technology:

                           (a) the Company possesses all right, title, and
                  interest in and to such item, free and clear of any
                  Encumbrance except as disclosed on Schedule 3.10;

                           (b) such item is not subject to any outstanding
                  Government Order, and no Action is pending or threatened,
                  which challenges the legality, validity, enforceability, use
                  or ownership of such item; and

                           (c) except as disclosed on Schedule 3.10, the Company
                  has not agreed and does not have a Contractual Obligation to
                  indemnify any Person for or against any interference,
                  infringement, misappropriation or other conflict with respect
                  to such item.

                  3.10.5. Schedule 3.10 identifies each item of Company
         Technology that any Person besides the Company owns and that is used by
         the Company in the Business pursuant to any license, sublicense or
         other Contractual Obligation (the "Licenses"). Except as disclosed on
         Schedule 3.10, there are no royalties for the use of any such Company
         Technology. The Company has made available to ViaCell true, accurate
         and complete copies of all of the Licenses, in each case, as amended or
         otherwise modified and in effect. With respect to each such item
         identified on Schedule 3.10: (a) such item is not subject to any
         outstanding Government Order, and no Action is pending or threatened
         which challenges the legality, validity or enforceability of such item
         and (b) none of the Sellers or the Company has granted any sublicense
         or similar right with respect to any License covering such item.

                  3.10.6. Except as set forth in Schedule 3.10, all current and
         former employees and contractors of the Company who contributed to the
         Company Technology in any way have executed enforceable Contractual
         Obligations that assign to the Company all the respective rights,
         including Intellectual Property, to any inventions, improvements,
         discoveries or information relating to the Business.

                  3.10.7. None of the Company Technology constitutes or is
         dependent on any open source computer code, and none of the Company
         Technology is subject to any License or other Contractual Obligation
         that would require the Company to divulge to any Person any source code
         or trade secret that is part of the Company Technology.

         3.11. Insurance. Schedule 3.11 is an accurate and complete list of all
insurance policies of the Company which relate to the Business (the "Insurance
Policies"). The Company has delivered to ViaCell true copies of all of the
Insurance Policies. The Company has taken all required action to maintain all of
the Insurance Policies in effect following the Closing, and has paid all
premiums due thereon in a timely manner. There are no claims currently

                                      -21-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

pending under any of the Insurance Policies, and, to the Company's Knowledge, no
basis for any such claims.

         3.12. Bank Accounts and Powers of Attorney. Schedule 3.12 sets forth an
accurate and complete list of (a) all bank accounts of the Company, together
with the names of all authorized signatories thereon; and (b) all powers of
attorney currently in effect for the Company.

         3.13. Affiliated Transactions. Except as set forth in Schedule 3.13,
the Company is not bound or party to any contract, commitment or understanding
with any of the Sellers, any manager or officer of the Company or any of its
affiliates or any member of such Seller's, manager's or officer's family or any
of their respective affiliates and none of the Sellers, any managers or officers
of the Company or any of its affiliates or any members of such Seller's,
manager's or officer's family or any of their respective affiliates owns or
otherwise has any rights to or interest in any asset, tangible or intangible,
which is used in the Business.

         3.14. Employees and Agents. Schedule 3.14 is an accurate and complete
list of all employees and contractors of the Company. The Company currently has
20 full time employees. To the Company's Knowledge, no executive, key employee
or group of employees has made any plans to terminate employment with the
Company. The Company is in compliance with all applicable labor and employment
laws and regulations, including, without limitation, laws prohibiting
discrimination and sexual harassment. The Company has no works council in place.
The Company has delivered to ViaCell a schedule which indicates, as to each
employee, (a) current salary, bonus, commissions and any other compensation; (b)
length of employment with the Company; and (c) most recent date and amount of
compensation increase, and such information is true and complete in all material
respects. The Company has delivered to ViaCell true and correct copies of all
agreements with employees of the Company.

         3.15. Employee Benefit Plans. Schedule 3.15 contains a description of
all employee benefit plans, superannuation plans, policies, practices and
arrangements of the Company (collectively, the "Company Plans"), including,
without limitation, pension, retirement, disability, sick leave, medical, dental
and other health insurance, life insurance, severance, stock options, deferred
compensation and vacation, and the Company has delivered to ViaCell true and
complete copies of all such Company Plans. All of the Company Plans are in
compliance with and have been administered in accordance with applicable law.

         3.16. Tax Returns and Payments. All tax returns and reports (including
but not limited to all laws imposing or relating to income tax, fringe benefits
tax, sales tax, goods and services tax, payroll tax, land tax, water and
municipal rates and stamp and customs duties) of the Company required to be
filed on or before the date hereof have been duly and timely filed on or before
such date or any properly extended date, and all taxes, assessments, fees,
interest, penalties and other governmental charges (collectively, "Taxes") upon
the Company, the Assets or the Business which are due and payable, other than
those which are presently payable without penalty or interest and which are
included in the Financial Statements, have been paid. As of the date hereof,
there are no tax liens on any of the Assets, and there is no basis for the
assertion of any such tax liens. There are no actions or

                                      -22-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

proceedings currently pending or, to the Company's Knowledge, threatened by any
taxing authority against the Company.

         3.17. Disclosures. No representation or warranty or other statement of
the Company contained in this Agreement and no statement of the Company
contained in (i) any Schedule to this Agreement, (ii) any instrument of transfer
or certificate required to be delivered pursuant to this Agreement, or (iii) the
documents required to be delivered pursuant to Section 8.3.3, Section 8.16 and
Section 8.18 of this Agreement, contains any untrue statement of a material
fact, and this Agreement does not omit to state a material fact necessary to
make the statements herein not misleading.

         3.18. Debt. The Company has no Liabilities in respect of Debt except as
set forth on Schedule 3.18. For each item of Debt, Schedule 3.18 correctly sets
forth the debtor, the principal amount of the Debt as of the date of this
Agreement, the creditor, the maturity date, and the collateral, if any, securing
the Debt. The Company has no Liability in respect of a Guarantee of any
Liability of any other Person.

         3.19. Real Property.

                  3.19.1. The Company maintains a base of operations in
         Langenfeld, Germany. The Company does not own any real property.
         Schedule 3.19 describes each leasehold interest in real property
         leased, subleased by, licensed or with respect to which a right to use
         or occupy has been granted to or by the Company (the "Real Property"),
         and specifies the lessor(s) of such leased property, and identifies
         each lease or any other Contractual Obligation under which such
         property is leased (the "Real Property Leases"). Except as described on
         Schedule 3.19 there are no written or oral subleases, licenses,
         concessions, occupancy agreements or other Contractual Obligations
         granting to any other Person the right of use or occupancy of the Real
         Property and there is no Person (other than the Company and any
         lessor(s) of leased Real Property) in possession of the leased Real
         Property. With respect to each Real Property Lease that is a sublease,
         to the Company's Knowledge, the representations and warranties set
         forth in Sections 3.19.2 and are true and correct with respect to the
         underlying lease.

                  3.19.2. The Real Property Leases do not impose material
         restrictions on any portion of the Business other than radius or use
         restrictions described on Schedule 3.19 that do not materially
         interfere with the Business. The Company is not obligated to pay any
         leasing or brokerage commission as a result of the Contemplated
         Transactions. There is no pending or, to the Company's Knowledge,
         threatened eminent domain taking or similar governmental taking
         affecting any of the Real Property. The Company has delivered to
         ViaCell true, correct and complete copies of the Real Property Leases
         including all amendments, modifications, notices or memoranda of lease
         thereto and all estoppel certificates or subordinations,
         non-disturbance and attornment agreements related thereto.

         3.20. Environmental Matters. The Company and its Predecessors are, and
have been, in compliance with all Environmental Laws. There has been no release
or threatened release of any pollutant, petroleum or any fraction thereof,
contaminant or toxic or hazardous material

                                      -23-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

         (including toxic mold), substance or waste (each a "Hazardous
         Substance") on, upon, into or from any site currently or heretofore
         owned, leased or otherwise used by the Company or a Predecessor in
         connection with or resulting from the conduct of the Company's
         Business. The Company does not use any underground storage tanks, PCBs
         (polychlorinated biphenyls) or PCB-containing equipment and does not
         store any hazardous waste, except in compliance with Environmental
         Laws.

                  3.21. Illegal Payments, etc. In the conduct of the Business,
         neither the Company nor, to the Company's Knowledge, any of its
         directors, officers, employees or agents, has (a) directly or
         indirectly, given, or agreed to give, any illegal gift, contribution,
         payment or similar benefit to any supplier, customer, governmental
         official or employee or other Person who was, is or may be in a
         position to help or hinder the Company (or assist in connection with
         any actual or proposed transaction) or made, or agreed to make, any
         illegal contribution, or reimbursed any illegal political gift or
         contribution made by any other Person, to any candidate for federal,
         state, local or foreign public office or (b) established or maintained
         any unrecorded fund or asset or made any false entries on any books or
         records for any purpose.

                  3.22. Brokers' Fees. Except as set forth in Schedule 3.22, the
         Company does not have any liability or obligation to pay any fees or
         commissions to any broker, finder or agent with respect to the
         transactions contemplated by this Agreement.

                  3.23. Company Assets. The Company's Assets include the
         following:

                           (i) an undrawn entitlement to receive research grants
                  in the amount of up to E3.0 million which remains to be
                  disbursed to the Company subject only to the conditions set
                  forth in the grant notice of the Forschungsinstitut Julich
                  GmbH dated May 21, 2002 and the letter of the
                  Forschungsinstitut Julich GmbH dated August 15, 2003 of which
                  the Company has delivered a true copy to ViaCell's counsel;

                           (ii) USSC Company Product candidates for orthopedic
                  indications in the pre-clinical research stage;

                           (iii) USSC Company Product candidates for
                  non-orthopedic (including cardiac) indications in the
                  pre-clinical research stage; and

                           (iv) all Intellectual Property rights related to the
                  USSC Company Products necessary for the full research and
                  development of the products described in (ii) and (iii) above
                  as currently conducted.

                  3.24. Closing Date Net Working Capital Statement. As of the
         Closing Date, the Closing Date Net Working Capital Statement delivered
         to ViaCell is true and correct in all respects.

         4. REPRESENTATIONS AND WARRANTIES RELATING TO THE SELLERS.

         Each Seller hereby severally, and not jointly, makes the following
representations and warranties to ViaCell (but only with respect to such Seller
and the Shares owned by such Seller),

                                      -24-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

each of which is complete and correct as of the execution of this Agreement and
on and as of the Closing Date:

                  4.1. Authorization. Each Seller has the requisite power and
         authority to enter into, execute, deliver and perform this Agreement
         and to consummate the transactions contemplated hereby. This Agreement
         has been duly executed and delivered by such Seller and constitutes the
         legal, valid and binding obligation of such Seller, enforceable against
         such Seller in accordance with its terms, except as the enforcement
         hereof may be limited by (i) applicable bankruptcy, insolvency,
         fraudulent transfer, reorganization, moratorium or other similar laws
         of general applicability relating to or affecting creditors' rights
         generally or (ii) general principles of equity, including those
         limiting the availability of specific performance, injunctive relief
         and other equitable remedies and those providing for equitable
         defenses.

                  4.2. No Violation or Approval. The execution, delivery and
         performance by such Seller of this Agreement and the consummation by
         such Seller of the transactions contemplated hereby will not result in
         a breach or violation of, or a default under, (a) any statute
         applicable to such Seller; (b) any agreement to which such Seller is a
         party or by which such Seller or any of such Seller's Shares is bound;
         or (c) any order, judgment, decree, rule or regulation of any court or
         any Governmental Authority having jurisdiction over such Seller or any
         of such Seller's Shares. Except as set forth on Schedule 4.2, no
         consent, approval, order or authorization of, or negotiation,
         declaration or filing with, any Governmental Authority or entity or any
         other party is required in connection with the execution, delivery or
         performance by such Seller of this Agreement or the consummation by
         such Seller of any of the transactions contemplated hereby.

                  4.3. Title to Shares. Each Seller is the sole legal and
         beneficial owner of, and has good and marketable title to, the number
         of Shares set forth opposite such Seller's name on Schedule 1 and
         Schedule 2, free and clear of any Encumbrance, except (i) restrictions
         on transfer under applicable securities laws and (ii) restrictions on
         transfer contained in any agreements containing transfer restrictions
         to which such Seller is a party as of the Closing Date, which are all
         duly waived by such Seller in accordance with Section 12.3. Such Seller
         does not own any Share, capital stock or right to acquire capital stock
         in the Company, other than those set forth opposite such Seller's name
         on Schedule 1 and Schedule 2. No share certificates ("Aktienurkunde")
         and no interim share certificates ("Zwischenscheine") have been issued
         for any of such Seller's Shares. Such Seller is not party to any
         option, warrant, purchase right or other contract or commitment that
         requires such Seller to sell, transfer or otherwise dispose of any
         capital stock of the Company, except for this Agreement. Such Seller
         has sole voting power and sole power to issue instructions with respect
         to voting, sole power of disposition, sole power of exercise or
         conversion and the sole power to demand appraisal rights, in each case
         with respect to all of the Shares set forth opposite such Seller's name
         on Schedule 1 and Schedule 2. Such Seller has full right, power and
         authority to enter into this Agreement and to sell, transfer and
         deliver the Shares set forth opposite such Seller's name on Schedule 1
         and Schedule 2, and upon assignment of such Shares to ViaCell at
         Closing, ViaCell will acquire good and marketable title to such Shares
         free of any Encumbrances, except (i) restrictions on transfer under
         applicable securities laws and (ii) restrictions on transfer contained
         in any agreements containing transfer restrictions to which

                                      -25-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

         such Seller is a party as of the Closing Date, which are all duly
         waived by such Seller in accordance with Section 12.3.

                  4.4. Qualification of the Sellers. Each Seller represents and
         warrants, with respect to itself and not with respect to any other
         Seller, that: (a) such Seller is acquiring the Series I Stock for such
         Seller's own account and not with a view to or for resale in connection
         with any distribution thereof within the meaning of Section 2(11) of
         the United States Securities Act of 1933, as amended (the "Securities
         Act"); (b) such Seller understands that such shares have not been
         registered under the Securities Act or any state securities laws by
         reason of specified exemptions from the registration provisions of the
         Securities Act which depend upon, among other things, the bona fide
         nature of his or its investment intent as expressed herein; (c) such
         Seller is an "accredited investor" within the meaning of Rule 501 of
         the Securities Act; (d) such Seller is able to bear the economic risk
         of investment in such shares and is experienced and has such knowledge
         and experience in financial and business matters that he or it is
         capable of evaluating the risks and merits of the transactions
         contemplated by this Agreement; and (e) such Seller acknowledges that
         such shares will bear a legend, such as the one specified in Section
         4.5 below, restricting transfer unless (i) the transfer is exempt from
         the registration requirements of the Securities Act and an opinion of
         counsel reasonably satisfactory to ViaCell that such transfer is exempt
         therefrom is delivered to ViaCell, or (ii) the transfer is made
         pursuant to an effective registration statement under the Securities
         Act. In addition, each Seller, other than the U.S. Sellers, represents
         and warrants, with respect to itself and not with respect to any other
         Seller, that: (a) such Seller is not a "U.S. Person" (as such term is
         defined in Rule 902(k) of Regulation S under the Securities Act) and is
         not acquiring the shares issuable pursuant to this Agreement for the
         account or benefit of a U.S. Person; (b) each Seller acknowledges that
         the shares issuable pursuant to this Agreement may not be sold,
         transferred, or otherwise disposed of except in accordance with the
         provisions of Regulation S of the Securities Act (Rules 901 through
         905), or pursuant to registration under the Securities Act or pursuant
         to an available exemption from registration under the Securities Act;
         and (c) each Seller agrees not to engage in hedging transactions with
         regard to the shares issuable pursuant to this Agreement unless in
         compliance with the Securities Act.

                  4.5. Restrictive Legends.

                           4.5.1. Each Seller, other than each U.S. Seller,
                  acknowledges that the certificates evidencing the Series I
                  Stock may bear substantially the following legends:

                                    (a) "THESE SECURITIES HAVE NOT BEEN
                           REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
                           AMENDED (THE "ACT"). THEY MAY NOT BE SOLD, OFFERED
                           FOR SALE, PLEDGED OR HYPOTHECATED EXCEPT (i) PURSUANT
                           TO THE PROVISIONS OF REGULATION S UNDER THE ACT, (ii)
                           PURSUANT TO A REGISTRATION STATEMENT IN EFFECT WITH
                           RESPECT TO THE SECURITIES UNDER THE ACT OR (iii) IN A
                           TRANSACTION WHICH IS EXEMPT FROM THE REGISTRATION
                           REQUIREMENTS OF THE ACT AS CONFIRMED IN AN OPINION OF
                           COUNSEL SATISFACTORY TO VIACELL (SUCH OPINION WILL
                           NOT BE REQUIRED IF THE SECURITIES ARE SOLD PURSUANT
                           TO RULE 144(k) OR RULE 144A OF THE ACT). HEDGING

                                      -26-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

                           TRANSACTIONS INVOLVING THESE SECURITIES MAY NOT BE
                           CONDUCTED UNLESS IN COMPLIANCE WITH THE ACT"; and

                                    (b) Any legends required by the Series I
                           Agreements.

                           4.5.2. Each U.S. Seller acknowledges that the
                  certificates evidencing the Series I Stock may bear
                  substantially the following legends:

                                    (a) "THESE SECURITIES HAVE NOT BEEN
                           REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
                           AMENDED (THE "ACT"). THEY MAY NOT BE SOLD, OFFERED
                           FOR SALE, PLEDGED OR HYPOTHECATED EXCEPT (i) PURSUANT
                           TO A REGISTRATION STATEMENT IN EFFECT WITH RESPECT TO
                           THE SECURITIES UNDER THE ACT OR (ii) IN A TRANSACTION
                           WHICH IS EXEMPT FROM THE REGISTRATION REQUIREMENTS OF
                           THE ACT AS CONFIRMED IN AN OPINION OF COUNSEL
                           SATISFACTORY TO VIACELL (SUCH OPINION WILL NOT BE
                           REQUIRED IF THE SECURITIES ARE SOLD PURSUANT TO RULE
                           144(k) OR RULE 144A OF THE ACT); and

                                    (b) Any legends required by the Series I
                           Agreements.

                  4.6. Brokers' Fees. Except as set forth in Schedule 4.6, each
         Seller represents and warrants that it has no liability or obligation
         to pay any fees or commissions to any broker, finder or agent with
         respect to the transactions contemplated by this Agreement.

         5. REPRESENTATIONS AND WARRANTIES OF VIACELL.

         ViaCell hereby makes the following representations and warranties to
the Sellers, each of which is complete and correct as of the execution of this
Agreement and on and as of the Closing Date:

                  5.1. Organization and Standing.

                                    (a) ViaCell and each of its Subsidiaries is
                           a corporation duly organized, validly existing and in
                           good standing under the laws of its jurisdiction of
                           organization and has full corporate power and
                           authority to own, lease and operate its assets,
                           properties and business and to carry on its business
                           as it is now being conducted. ViaCell and each of its
                           Subsidiaries is duly qualified to transact business
                           as a foreign corporation and is in good standing in
                           all jurisdictions in which such qualification is
                           required by law except for jurisdictions in which the
                           failure to so qualify could not reasonably be
                           expected to have a Material Adverse Effect.

                                    (b) ViaCell has previously provided to the
                           Sellers true and complete copies of its Certificate
                           of Incorporation and By Laws as presently in effect,
                           and ViaCell is not in default in the performance,
                           observation or fulfillment of any of such documents.
                           The minute books of ViaCell made available to the
                           Sellers contain true and complete records of all
                           meetings and consents in lieu of meetings of the
                           Board of Directors (and any committees thereof) and
                           of the stockholders of ViaCell since the time of
                           ViaCell's incorporation and accurately reflect all
                           transactions referred to in such

                                      -27-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

                           minutes and consents in lieu of meetings. The stock
                           books of ViaCell are true and complete.

                  5.2. ViaCell Subsidiaries. Schedule 5.2 sets forth all of
         ViaCell's Subsidiaries (the "ViaCell Subsidiaries"), the jurisdiction
         in which each is organized or incorporated, and each jurisdiction in
         which it is qualified or otherwise authorized to do business. Other
         than the ViaCell Subsidiaries, ViaCell has no other Subsidiaries and
         does not own or control, directly or indirectly, any shares of capital
         stock of any other corporation or any interest in any partnership,
         joint venture or other non corporate business enterprise. ViaCell owns
         all of the outstanding capital stock of each ViaCell Subsidiary.

                  5.3. Authority to Execute and Perform Agreements. ViaCell has
         the full corporate power and authority to enter into, execute and
         deliver this Agreement and all Ancillary Agreements and to perform
         fully its obligations hereunder and thereunder. The execution and
         delivery of this Agreement and the Ancillary Agreements, and the
         consummation of the transactions contemplated hereby and thereby have
         been duly authorized by the Board of Directors and the stockholders of
         ViaCell. No other action on the part of ViaCell is necessary to
         consummate the transactions contemplated hereby. This Agreement and the
         Ancillary Agreements have been duly executed and delivered by ViaCell
         and, assuming the due authorization, execution and delivery of this
         Agreement and the Ancillary Agreements by the other parties thereto,
         this Agreement and the Ancillary Agreements constitute valid and
         binding obligations of ViaCell, enforceable against it in accordance
         with their terms, subject to bankruptcy, insolvency, fraudulent
         transfer, reorganization, moratorium and similar laws of general
         applicability relating to or affecting creditors' rights and to general
         principles of equity.

                  5.4. Capitalization and Title to Shares.

                                    (a) Before giving effect to the Contemplated
                           Transactions and the Financing, the authorized
                           capital stock of ViaCell consists of (i) 80,000,000
                           shares of ViaCell Common Stock, of which 2,634,299
                           shares are issued and outstanding, and 6,410,000
                           shares are reserved for issuance pursuant to
                           outstanding options and warrants, and (ii) 28,325,000
                           shares of Preferred Stock, $.01 par value per share,
                           100,000 shares of which have been designated as
                           Series A Preferred Stock, $.01 par value per share
                           (the "Series A Stock"), all of which are issued and
                           outstanding; 82,857 shares of which have been
                           designated as Series B Preferred Stock, $.01 par
                           value per share (the "Series B Stock"), all of which
                           are issued or outstanding; 919,220 shares of which
                           have been designated as Series C Preferred Stock,
                           $.01 par value per share (the "Series C Stock"), all
                           of which are issued and outstanding; 1,500,000 shares
                           of which have been designated as Series D Preferred
                           Stock, $.01 par value per share (the "Series D
                           Stock"), all of which are issued and outstanding;
                           1,983,334 shares of which have been designated as
                           Series E Preferred Stock, $.01 par value per share
                           (the "Series E Stock"), all of which are issued and
                           outstanding; 2,666,666 shares of which have been
                           designated as Series F Stock, $.01 par value per
                           share (the "Series F Stock"), all of which are issued
                           and outstanding; 3,666,667 of which have been
                           designated as Series G Stock, $.01 par value per
                           share (the "Series G Stock"), all of which are issued
                           and outstanding; 7,577,334 shares of which have been
                           designated
                                      -28-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

                           as Series H Preferred Stock, $.01 par value per share
                           (the "Series H Stock"), all of which are issued and
                           outstanding; 5,575,000 shares of Series I Stock,
                           2,075,000 of which are issued and outstanding; and
                           3,750,000 shares of which have been designated as
                           Series J Preferred Stock, $.01 par value per share
                           (the "Series J Stock"), of which 1,440,000 shares are
                           issued and outstanding. All of the issued and
                           outstanding shares of ViaCell's Common Stock, Series
                           A Stock, Series B Stock, Series C Stock, Series D
                           Stock, Series E Stock, Series F Stock, Series G
                           Stock, Series H Stock and Series I Stock are duly
                           authorized and are validly issued, fully paid, and
                           nonassessable. Since January 1, 2001, ViaCell has not
                           made repurchases or redemptions of shares of its
                           capital stock. All the issued and outstanding shares
                           of capital stock of ViaCell have been offered, issued
                           and sold by ViaCell in compliance with applicable
                           federal and state securities laws. Schedule 5.4 sets
                           forth a true and complete list of (A) each
                           stockholder of ViaCell showing the number of shares
                           of ViaCell Common Stock, Preferred Stock, or other
                           securities of ViaCell held by each such stockholder
                           as of the date hereof and (B) each holder of options
                           and warrants to acquire ViaCell Common Stock with
                           vesting schedules and exercise prices.

                                    (b) Except for the outstanding Preferred
                           Stock, and options and warrants described in 5.4(a)
                           above, and except as set forth on Schedule 5.4, there
                           are not, as of the date hereof, any other shares of
                           capital stock of ViaCell authorized or outstanding or
                           any subscriptions, options, conversion or exchange
                           rights, warrants, repurchase or redemption
                           agreements, or other agreements, claims or
                           commitments of any nature whatsoever obligating
                           ViaCell or any ViaCell Subsidiary to issue, transfer,
                           deliver or sell, or cause to be issued, transferred,
                           delivered, sold, repurchased or redeemed, additional
                           shares of the capital stock or other securities of
                           ViaCell or any ViaCell Subsidiary or obligating
                           ViaCell or any ViaCell Subsidiary to grant, extend or
                           enter into any such agreement. Except as provided in
                           this Agreement, the Ancillary Agreements and the
                           Series I Agreements, neither ViaCell nor any ViaCell
                           Subsidiary has any stockholder agreements, voting
                           trusts, proxies or other agreements, instruments,
                           including bonds, debentures, notes or other
                           obligations, or understandings with respect to the
                           voting of the capital stock of ViaCell or the ViaCell
                           Subsidiaries.

                                    (c) The issuance and delivery of the Series
                           I Stock hereunder, and the issuance and delivery of
                           the shares of Common Stock issuable upon conversion
                           of such Series I Stock, have been duly authorized by
                           all necessary corporate action on the part of
                           ViaCell, and all such shares have been duly reserved
                           for issuance. The Series I Stock when so issued and
                           delivered against payment therefor in accordance with
                           the provisions of this Agreement and the shares of
                           Common Stock issuable upon conversion of the Series I
                           Stock when issued upon such conversion issued in
                           connection with such Series I Stock will be duly and
                           validly issued, fully paid and non-assessable.

                  5.5. Financial Statements. The audited balance sheet of
         ViaCell as at December 31, 2002, and the related combined statement of
         operations for the fiscal year then ended, and the unaudited combined
         balance sheet of ViaCell as of June 30, 2003 and related statements of
         operations for the period then ended, all of which are included on
         Schedule 5.5, fairly present

                                      -29-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

         the financial condition and results of operations of ViaCell as of the
         dates thereof and for the period then ended in accordance with GAAP,
         consistently applied throughout the periods covered thereby, except to
         the extent otherwise disclosed in such financial statements or on
         Schedule 5.5. The foregoing financial statements of ViaCell are
         sometimes herein called the "ViaCell Financial Statements," the balance
         sheet of ViaCell as at June 30, 2003, is sometimes herein called the
         "ViaCell Balance Sheet" and June 30, 2003 is sometimes herein called
         the "ViaCell Balance Sheet Date."

                  5.6. No Material Adverse Change. Since the ViaCell Balance
         Sheet Date, there have been no changes in the assets, properties,
         business, operations or condition (financial or otherwise) of ViaCell
         or any ViaCell Subsidiary which either individually or in the aggregate
         is reasonably likely to have a Material Adverse Effect, nor does
         ViaCell or any ViaCell Subsidiary know of any such change that is
         threatened, nor has there been any damage, destruction or loss
         materially and adversely affecting the assets, properties, business,
         operations or condition (financial or otherwise) of ViaCell or any
         ViaCell Subsidiary, whether or not covered by insurance; and

                           (a) except as set forth on Schedule 5.6 or in
                  connection with the Contemplated Transactions or the
                  Financing, since the ViaCell Balance Sheet Date neither
                  ViaCell nor any ViaCell Subsidiary has:

                                    (i) incurred any indebtedness for borrowed
                           money;

                                    (ii) declared or paid any dividend or
                           declared or made any other distribution of any kind
                           to its stockholders, or made any direct or indirect
                           redemption, retirement, purchase or other acquisition
                           of any shares of its capital stock;

                                    (iii) made any loan or advance to any of its
                           stockholders, officers, directors, employees,
                           consultants, agents or other representatives (other
                           than travel advances made in the Ordinary Course of
                           Business), or made any other loan or advance
                           otherwise than in the Ordinary Course of Business;

                                    (iv) made any payment or commitment to pay
                           any severance or termination pay to any of its
                           officers, directors, employees, consultants, agents
                           or other representatives, other than payments to, or
                           commitments to pay, persons made in the Ordinary
                           Course of Business;

                                    (v) except in the Ordinary Course of
                           Business: entered into any lease (as lessor or
                           lessee); sold, abandoned or made any other
                           disposition of any of its assets or properties;
                           granted or suffered any lien or other encumbrance on
                           any of its assets or properties; entered into or
                           amended any contract or other agreement to which it
                           is a party, or by or to which it or its assets or
                           properties are bound or subject, or pursuant to which
                           it agrees to indemnify any party or to refrain from
                           competing with any party;

                                      -30-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

                                    (vi) except for inventory or equipment
                           acquired in the Ordinary Course of Business, made any
                           acquisition of all or any part of the assets,
                           properties, capital stock or business of any other
                           person;

                                    (vii) incurred any contingent liability as a
                           guarantor or otherwise with respect to the
                           obligations of others or cancelled any material debt
                           or claim owing to, or waived any material right of,
                           ViaCell or any ViaCell Subsidiary;

                                    (viii) incurred any damage, destruction or
                           loss, whether or not covered by insurance, materially
                           and adversely affecting the properties, assets or
                           business of ViaCell;

                                    (ix) made any change in accounting methods
                           or practices, credit practices or collection policies
                           used by ViaCell or any ViaCell Subsidiary; or

                                    (x) made any commitment, understanding or
                           agreement (through any officer or employee thereof)
                           to do any of the things described in the preceding
                           clauses (i) through (ix) (other than this Agreement).

                           (b) Since the ViaCell Balance Sheet Date, ViaCell and
                  each of the ViaCell Subsidiaries have conducted its business
                  only in the ordinary course and consistently with its prior
                  practices.

         5.7. Tax Matters.

                           (a) All Tax Returns required to be filed on or before
                  the date hereof by or with respect to ViaCell and the ViaCell
                  Subsidiaries have been filed within the time and in the manner
                  prescribed by law. All such Tax Returns are true, correct, and
                  complete, and all Taxes owed by ViaCell or the ViaCell
                  Subsidiaries, whether or not shown on any Tax Return, have
                  been paid. ViaCell and each of the ViaCell Subsidiaries file
                  Tax Returns in all jurisdictions where they are required to so
                  file, and no claim has ever been made in writing to ViaCell or
                  any ViaCell Subsidiary by any taxing authority in any other
                  jurisdiction that ViaCell or any ViaCell Subsidiary is or may
                  be subject to taxation by that jurisdiction.

                           (b) There are no liens or other encumbrances with
                  respect to Taxes upon any of the assets or properties of
                  ViaCell or any ViaCell Subsidiary, other than with respect to
                  Taxes not yet due and payable.

                           (c) To the knowledge of ViaCell, no audit is
                  currently pending with respect to any Tax Return of ViaCell or
                  any ViaCell Subsidiary, nor is ViaCell or its officers or
                  directors aware of any information which has caused or should
                  reasonably cause them to believe that an audit by any tax
                  authority may be forthcoming. No deficiency for any Taxes has
                  been proposed in writing against ViaCell or any ViaCell
                  Subsidiary, which deficiency has not been paid in full or
                  otherwise resolved. No issue relating to ViaCell or the
                  ViaCell Subsidiaries or involving any Tax for which ViaCell or
                  any ViaCell Subsidiary was liable has been resolved in favor
                  of any taxing authority in any audit or examination which, by
                  application of the same principles, could

                                      -31-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

                  reasonably be expected to result in a deficiency for Taxes of
                  ViaCell or any ViaCell Subsidiary for any subsequent period.

                           (d) None of ViaCell's Tax Returns for taxable periods
                  ended on or after December 31, 1998 have been audited or are
                  currently the subject of audit. Except as set forth on
                  Schedule 5.7, there are no outstanding agreements, waivers or
                  arrangements extending the statutory period of limitation
                  applicable to any claim for, or the period for the collection
                  or assessment of, Taxes due from or with respect to ViaCell or
                  any ViaCell Subsidiary for any taxable period, no power of
                  attorney granted by or with respect to ViaCell or any ViaCell
                  Subsidiary relating to Taxes is currently in force, and no
                  extension of time for filing any Tax Return required to be
                  filed by or on behalf of ViaCell or any ViaCell Subsidiary is
                  in force.

                           (e) The unpaid Taxes of ViaCell and each ViaCell
                  Subsidiary for all taxable periods (or portions thereof)
                  ending on or prior to the Closing Date did not, as of the
                  ViaCell Balance Sheet Date, exceed the reserve for Tax
                  liability (rather than any reserve for deferred Taxes
                  established to reflect timing differences between book and Tax
                  income) set forth on the face of the ViaCell Balance Sheet
                  (rather than in any notes thereof).

                           (f) Neither ViaCell nor any ViaCell Subsidiary is a
                  "consenting corporation" within the meaning of Section 341(f)
                  of the Code, and no consent to the application of Section
                  341(f)(2) of the Code (or any predecessor provision) has been
                  made or filed by or with respect to ViaCell or any ViaCell
                  Subsidiary or any of their assets or properties. None of the
                  assets or properties of ViaCell or any ViaCell Subsidiary are
                  or will be required to be treated as being (i) owned by any
                  other person pursuant to the provisions of section 168(f)(8)
                  of the Internal Revenue Code of 1954, as amended and in effect
                  immediately before the enactment of the Tax Reform Act of
                  1986, or (ii) tax-exempt use property within the meaning of
                  section 168(h)(1) of the Code. Neither ViaCell nor any ViaCell
                  Subsidiary has agreed, or is required, to make any adjustment
                  under Section 481(a) of the Code by reason of a change in
                  accounting method or otherwise.

                           (g) Neither ViaCell nor any ViaCell Subsidiary has
                  been and is currently in violation (or, with or without notice
                  or lapse of time or both, would be in violation) of any
                  applicable law or regulation relating to the payment,
                  collection, or withholding of Taxes, and the remittance
                  thereof, and all withholding and payroll Tax requirements
                  required to be complied with by ViaCell or the ViaCell
                  Subsidiary up to and including the date hereof have been
                  satisfied.

                           (h) Neither ViaCell nor any ViaCell Subsidiary is or
                  has ever been (i) included in any consolidated, combined, or
                  unitary Tax Return or (ii) a party to or bound by, nor does it
                  have or has it ever had any obligation under, any Tax sharing
                  agreement or similar contract or arrangement. Neither ViaCell
                  nor any ViaCell Subsidiary has any liability for the Taxes of
                  any other person under Treasury Regulation Section 1.1502-6
                  (or any similar provision of state, local, or foreign law), as
                  a transferee or successor, by contract, or otherwise.

                                      -32-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

            (i) Neither ViaCell nor any ViaCell Subsidiary is a party to any
         contract or agreement, plan, or arrangement concerning any person that,
         individually or collectively with other similar arrangements, could
         reasonably be expected to give rise to the payment of any amount that
         would not be deductible by ViaCell by reason of Section 280G of the
         Code.

            (j) ViaCell and the ViaCell Subsidiaries are domestic corporations
         within the meaning of Section 7701(a)(4) of the Code.

      5.8.  Compliance with Laws.

            (a) Neither ViaCell nor any ViaCell Subsidiary is in violation of
         any order, judgment, injunction, award or decree binding upon it.
         Neither ViaCell nor any ViaCell Subsidiary is in violation of any (i)
         federal, state or local law, ordinance or regulation of any
         governmental or regulatory body applicable to its business or assets,
         including without limitation, regulations and requirements of any state
         or other department of public health, the FDA and the Occupational
         Safety and Health Administration ("OSHA"), and (ii) laws, ordinances,
         regulations and other requirements respecting public health, labor,
         employment and employment practices, terms and conditions of employment
         and wages and hours, or relating to the uses of its assets, including,
         without limitation, laws relating to emissions, discharges, releases of
         Hazardous Substances, as defined in Section 3.20 (including, without
         limitation, ambient air, surface water, ground water or land), or
         otherwise relating to the manufacture, processing, distribution, use,
         treatment, storage, disposal, transport or handling of Hazardous
         Substances. Neither ViaCell nor any ViaCell Subsidiary has ever
         received notice of any citation, fine or penalty imposed or asserted
         against ViaCell or any ViaCell Subsidiary for any such violation or
         alleged violation.

            (b) Except as disclosed on Schedule 5.8, ViaCell and the ViaCell
         Subsidiaries have all the licenses, permits, franchises, orders or
         approvals of any federal, state, local or foreign governmental or
         regulatory body, including, but not limited to, licenses issued by
         state or other departments of public health, the FDA, the OSHA, or
         otherwise relating to employment, health or environmental matters
         (collectively, the "ViaCell Permits") material to the conduct of their
         businesses as currently conducted or as reasonably expected to be
         conducted. The ViaCell Permits are in full force and effect; any
         applications for renewal necessary to maintain any ViaCell Permit in
         effect have been filed; and no proceeding is pending, or to the best
         knowledge of ViaCell, threatened to revoke or limit any ViaCell Permit.

      5.9. Consents; No Breach. All consents, permits, authorizations and
   approvals from any person pursuant to applicable law or contracts or other
   agreements with ViaCell or any ViaCell Subsidiary, that are required in
   connection with the performance of ViaCell's obligations under this
   Agreement, are set forth on Schedule 5.9. The execution, delivery and
   performance of this Agreement and the consummation of the transactions
   contemplated hereby and thereby will not (a) violate any provision of the
   Certificate of Incorporation or By-laws of ViaCell; (b) except as set forth
   on Schedule 5.9, violate, conflict with or result in the breach of any of the
   terms or conditions of, result in modification of the effect of, or give


                                      -33-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

   any other contracting party the right to terminate, or constitute (or with
   notice or lapse of time or both constitute) a default under, any instrument,
   contract or other agreement to which ViaCell or any ViaCell Subsidiary is a
   party or to which it or any of its assets or properties may be bound or
   subject; (c) violate any order, judgment, injunction, award or decree of any
   court, arbitrator or governmental or regulatory body against, or binding
   upon, ViaCell or upon the securities, properties, assets or business of
   ViaCell; (d) violate any statute, law or regulation of any jurisdiction as
   such statute, law or regulation relates to ViaCell or to the securities,
   properties, assets or business of ViaCell; (e) violate any ViaCell Permit;
   (f) except as set forth on Schedule 5.9, require the approval or consent of
   any foreign, federal, state, local or other governmental or regulatory body
   or the approval or consent of any other person; or (g) result in the creation
   of any lien or other encumbrance on the assets or properties of ViaCell.

      5.10. Actions and Proceedings. Except as disclosed in Schedule 5.10, there
   are no outstanding orders, judgments, injunctions, awards or decrees of any
   court, governmental or regulatory body or arbitration tribunal against or
   involving ViaCell or any ViaCell Subsidiary or any of their securities,
   assets, or properties. Except as disclosed in Schedule 5.10, there are no
   actions, suits or claims or legal, administrative or arbitration proceedings,
   as to which ViaCell or any ViaCell Subsidiary has been served, or
   investigations (whether or not the defense thereof or liabilities in respect
   thereof are covered by insurance) pending or, to the best knowledge of
   ViaCell, threatened against ViaCell or any ViaCell Subsidiary or involving
   any of their securities, assets or properties. To the knowledge of ViaCell,
   there is no fact, event or circumstance that could reasonably be expected to
   give rise to any suit, action, claim, investigation or proceeding that
   individually or in the aggregate, could reasonably be expected to have a
   Material Adverse Effect or materially interfere with ViaCell's ability to
   consummate the transactions contemplated hereby.

      5.11. Contracts and Other Agreements. Schedule 5.11 sets forth all of the
   following contracts and other agreements to which ViaCell or any ViaCell
   Subsidiary is currently a party or by or to which it or its assets or
   properties are bound or subject (and under which it has current or future
   rights or obligations) and which are material to the operation or value of
   ViaCell and the ViaCell Subsidiaries taken as a whole, including without
   limitation:

            (a) contracts and other agreements with any current or former
         officer, director, stockholder, employee, consultant, agent or other
         representative of ViaCell or any ViaCell Subsidiary and contracts and
         other agreements for the payment of fees or other consideration to any
         entity in which any officer or director of ViaCell or any ViaCell
         Subsidiary has an interest;

            (b) contracts and other agreements with any labor union or
         association representing any employee of ViaCell or any ViaCell
         Subsidiary or otherwise providing for any form of collective
         bargaining;

            (c) contracts and other agreements for the purchase or sale of
         materials, supplies, equipment, merchandise or services that contain an
         escalation, renegotiation or redetermination clause or that obligate
         ViaCell or any ViaCell Subsidiary to


                                      -34-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

         purchase all or substantially all of its requirements of a particular
         product from a supplier, or for periodic minimum purchases of a
         particular product from a supplier;

            (d) contracts and other agreements for the sale of any of the assets
         or properties of ViaCell or any ViaCell Subsidiary other than in the
         Ordinary Course of Business or for the grant to any person of any
         options, rights of first refusal, or preferential or similar rights to
         purchase any of such assets or properties;

            (e)  partnership or joint venture agreements;

            (f) contracts or other agreements under which ViaCell or any ViaCell
         Subsidiary agrees to indemnify any party or to share the tax liability
         of any party;

            (g) contracts, options and other agreements for the purchase of any
         asset, tangible or intangible calling for an aggregate purchase price
         or payments in any one year of more than $100,000 in any one case (or
         in the aggregate, in the case of any related series of contracts and
         other agreements);

            (h) contracts and other agreements that cannot by their terms be
         canceled by ViaCell or any ViaCell Subsidiary and any successor or
         assignee of ViaCell or any ViaCell Subsidiary without liability,
         premium or penalty on no less than thirty days notice;

            (i)  contracts and other agreements with customers or
         suppliers for the sharing of fees, the rebating of charges or
         other similar arrangements;

            (j) contracts and other agreements containing obligations or
         liabilities of any kind to holders of the securities of ViaCell as such
         (including, without limitation, an obligation to register any of such
         securities under any federal or state securities laws);

            (k) contracts and other agreements containing covenants of ViaCell
         or any ViaCell Subsidiary not to compete in any line of business or
         with any person or covenants of any other person not to compete with
         ViaCell or any ViaCell Subsidiary in any line of business;

            (l) contracts and other agreements relating to the acquisition by
         ViaCell or any ViaCell Subsidiary of any operating business or the
         capital stock of any other person;

            (m) contracts and other agreements requiring the payment to any
         person of a commission or fee, including contracts or other agreements
         with consultants which provide for aggregate payments in excess of
         $100,000;

            (n) contracts, indentures, mortgages, promissory notes, loan
         agreements, guaranties, security agreements, pledge agreements, and
         other agreements relating to the borrowing of money or securing any
         such liability;

            (o)  distributorship or licensing agreements;


                                      -35-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

            (p) contracts under which ViaCell or the ViaCell Subsidiary will
         acquire or has acquired ownership of, or license to, intangible
         property, including software (other than software licensed by ViaCell
         as an end user for less than $100,000 and not distributed by it);

            (q) leases, subleases or other agreements under which ViaCell or the
         ViaCell Subsidiary is lessor or lessee of any real property; or

            (r) any other material contract or other agreement whether or not
         made in the Ordinary Course of Business the breach of which would have
         or may have a Material Adverse Effect.

    To the extent requested by the Sellers, ViaCell has made available to the
Sellers true and complete copies of all of the contracts and other agreements
(and all amendments, waivers or other modifications thereto) set forth on
Schedule 5.11. All of the contracts and other agreements listed on Schedule 5.11
are valid, in full force and effect, binding upon ViaCell or the applicable
ViaCell Subsidiary, and to the knowledge of ViaCell, binding upon the other
parties thereto in accordance with their terms, except where the failure to be
valid, binding, in full force and effect would not have a Material Adverse
Effect. ViaCell or the ViaCell Subsidiary has satisfied in all material respects
or provided for in all material respects all of its liabilities and obligations
thereunder which are presently required to be satisfied or provided for, and is
not in default under any of them, except where the failure to so satisfy or
provide or not be in default would not have a Material Adverse Effect. To the
knowledge of ViaCell, no other party to any such contract or other agreement is
in material default thereunder, nor, to the best knowledge of ViaCell, does any
condition exist that with notice or lapse of time or both would constitute a
default thereunder, except for defaults that would not, singly or in the
aggregate, have a Material Adverse Effect.

      5.12. Title to Properties; Absence of Liens and Encumbrances.

            (a) Neither ViaCell nor any ViaCell Subsidiary owns any real
         property or any buildings or other structures nor does it have options
         or any contractual obligations to purchase or acquire any interest in
         real property. Schedule 5.12 sets forth all real property leases to
         which each of ViaCell and the ViaCell Subsidiaries is a party and each
         amendment thereto. All such current leases are in full force and
         effect, are valid and effective in accordance with their respective
         terms, and there is not, under any of such leases, any existing default
         or event of default (or event which with notice or lapse of time, or
         both, would constitute a default) that would give rise to a claim in an
         amount greater than $20,000.

            (b) ViaCell and each ViaCell Subsidiary owns outright and has good
         and valid title to, or, in the case of leased properties and assets,
         valid leasehold interests in all of its tangible properties and assets,
         real, personal and mixed, used or held for use in its business,
         including, without limitation, all of the assets and properties
         reflected on the ViaCell Balance Sheet, and such properties and assets,
         as well as all other properties and assets of ViaCell or the ViaCell
         Subsidiaries, whether tangible or intangible, are free and clear of any
         mortgage, pledge, security interest, claim, lien, or other


                                      -36-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

         encumbrance, except for (a) assets and properties disposed of, or
         subject to purchase or sales orders, in the ordinary course of business
         since the applicable ViaCell Balance Sheet Date; (b) liens or other
         encumbrances securing the claims of materialmen, carriers, landlords
         and like persons, all of which are not yet due and payable, or (c)
         purchase money liens, all such claims, liens, or other encumbrances of
         which are set forth on Schedule 5.12.

      5.13. Condition and Sufficiency of Assets. The buildings, plants,
   structures, equipment, furniture, leasehold improvements, fixtures, vehicles,
   any related capitalized items and other tangible property material to the
   business of ViaCell and each ViaCell Subsidiary are structurally sound, are
   in good operating condition and repair, ordinary wear and tear excepted, and
   are adequate for the uses to which they are being put, and none of such
   buildings, plants, structures, equipment, furniture, leasehold improvements,
   fixtures, vehicles are in need of maintenance or repairs except for ordinary
   routine maintenance and repairs. The buildings, plants, structures,
   equipment, furniture, leasehold improvements, fixtures, vehicles of ViaCell
   and each ViaCell Subsidiary are sufficient for the continued operation of the
   business of ViaCell and each ViaCell Subsidiary after the Closing in
   substantially the same manner as conducted on the date of the Closing.
   Neither ViaCell nor any ViaCell Subsidiary has received notice that any of
   such property is in violation of any existing law or any building, zoning,
   health, safety or other ordinance, code or regulation.

      5.14. Intellectual Property. Schedule 5.14 sets forth all of the patents,
   trademarks, service marks trade names, trade secrets, franchises, inventions
   and copyrights, all information regarding the registration of any of the
   foregoing, and all licenses relating to any of the foregoing (collectively,
   the "Proprietary Rights") of ViaCell and each ViaCell Subsidiary that are
   material to their businesses as presently conducted or as contemplated to be
   conducted. Schedule 5.14 sets forth a list of all intellectual property,
   including but not limited to patents and licenses that may, to the knowledge
   of ViaCell, be required to commercialize ViaCell's and each ViaCell
   Subsidiary's current projects under research and development. Except as set
   forth on Schedule 5.14, ViaCell and each ViaCell Subsidiary owns, is licensed
   to use or otherwise has the full legal right to use all of their Proprietary
   Rights. Neither ViaCell nor any ViaCell Subsidiary has received any written
   notices of infringement by ViaCell or any ViaCell Subsidiary of any
   Proprietary Rights of others. To the knowledge of ViaCell, none of the
   present activities of ViaCell or any ViaCell Subsidiary, or their respective
   products or assets infringe on any Proprietary Rights of others; and ViaCell
   is not aware of any infringement or violation by others of its or any of its
   Subsidiaries' Proprietary Rights. ViaCell and each ViaCell Subsidiary has the
   unencumbered right to use all trade secrets, customer lists, procedures,
   processes, and other information required for its services or its business as
   presently conducted. ViaCell and each ViaCell Subsidiary has taken
   commercially reasonable steps to establish and preserve the ownership of its
   Proprietary Rights. All key employees of ViaCell and each ViaCell Subsidiary
   have entered into an agreement with respect to confidentiality,
   non-competition and inventions. ViaCell is not aware of any violation of the
   confidentiality of its or any of its Subsidiaries' Proprietary Rights. To the
   best knowledge of ViaCell, neither ViaCell nor any ViaCell Subsidiary is
   making unauthorized use of any confidential information or trade secrets of
   any person, including without limitation any former employer of any past or
   present employees of ViaCell or any ViaCell Subsidiary. To the best knowledge
   of ViaCell,


                                      -37-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

   its employees do not have any agreements or arrangements with former
   employers currently in effect relating to confidential information or trade
   secrets of such employers. To the best knowledge of ViaCell, none of the
   activities of the employees of ViaCell on behalf of ViaCell or any ViaCell
   Subsidiary violate any valid and enforceable agreements or arrangements that
   any such employees have with former employers.

      5.15. Absence of Undisclosed Liabilities. As of the ViaCell Balance Sheet
   Date, neither ViaCell nor any ViaCell Subsidiary had any liabilities of any
   nature, whether accrued, absolute, contingent or otherwise (including,
   without limitation, liabilities as guarantor or otherwise with respect to
   obligations of others or material liabilities for taxes due or then accrued
   or to become due), that would be required under GAAP to be shown or disclosed
   on the ViaCell Balance Sheet that were not fully and adequately reflected or
   reserved against on the ViaCell Balance Sheet. Neither ViaCell nor any
   ViaCell Subsidiary has any such liabilities other than liabilities (a) fully
   and adequately reflected or reserved against on the ViaCell Balance Sheet,
   and (b) incurred since the ViaCell Balance Sheet Date in the Ordinary Course
   of Business.

      5.16. Commercial Relationships. The relationships of ViaCell and its
   Subsidiaries with their suppliers, distributors, collaborators and licensors
   are generally good commercial working relationships. No such entity has
   canceled or otherwise terminated its relationship with ViaCell or any ViaCell
   Subsidiary (except in the course of the natural expiration of any contracts
   governing such relationship) or has, during the last twelve months,
   materially altered its relationship with ViaCell or any ViaCell Subsidiary.
   Neither ViaCell nor any ViaCell Subsidiary knows of any plan or intention of
   any such entity, and has not received any written threat or notice from any
   such entity, to terminate, cancel or otherwise materially and adversely
   modify its relationship with ViaCell or any ViaCell Subsidiary nor to
   decrease materially or limit its services, supplies or materials to ViaCell
   or any ViaCell Subsidiary or its usage, or purchase of the services or
   products of ViaCell or any ViaCell Subsidiary except in the course of the
   natural expiration of any contracts governing such relationship.

      5.17. Employee Benefit Plans. Schedule 5.17 sets forth a correct and
   complete list of all pension, profit sharing, retirement, deferred
   compensation, welfare, insurance, disability, bonus, vacation pay, severance
   pay and similar plans, programs or arrangements, including without limitation
   all employee benefit plans as defined in Section 3(3) of ERISA with respect
   to which ViaCell is the "Plan Sponsor" within the meaning of Section 3(16)(B)
   of ERISA, or in which ViaCell participates (the "Plans"). ViaCell has never
   maintained or contributed to a defined benefit pension plan that is subject
   to Title IV of ERISA. ViaCell has never maintained or contributed to any
   "multiemployer plan" as defined in Section 4001(a)(3) of ERISA, and ViaCell
   has not incurred any material liability under Sections 4062, 4063 or 4201 of
   ERISA. Each Plan which is intended to be qualified under Section 401(a) or
   501(c)(9) of the Code has received a favorable determination letter from the
   Internal Revenue Service. Each Plan has been administered in all material
   respects in accordance with the terms of such Plan and the provisions of any
   and all applicable statutes, orders or governmental rules or regulations,
   including without limitation ERISA and the Code. To the knowledge of ViaCell,
   nothing has been done or omitted to be done with respect to any Plan which is
   intended to comply with Section 401(a) of the Code that would adversely
   affect the qualified status of such Plan or result in any material liability
   on the part


                                      -38-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

   of ViaCell including, without limitation, under Title I of ERISA or Section
   4975 of the Code. All material reports, returns, notices and documents
   required to be filed with respect to all the Plans, including without
   limitation annual reports on Form 5500, have been timely filed. All
   contributions required by law or the terms of any Plan have been made. All
   claims for welfare benefits incurred by employees of ViaCell on or before the
   Closing are or will be fully covered by third-party insurance policies or
   programs. Except for continuation of health coverage to the extent required
   under Section 4980B of the Code, applicable state law or as otherwise set
   forth in this Agreement, there are no obligations under any Plan providing
   health or other welfare benefits after termination of employment. For
   purposes of this Section 5.17, references to ViaCell include ViaCell and each
   ViaCell Subsidiary and its ERISA Affiliates. An "ERISA Affiliate" of ViaCell
   means any trade or business (whether or not incorporated) that together with
   ViaCell would have been deemed a "single employer" within the meaning of
   Section 4001(b) of ERISA or Section 414(m) of the Code at any time within the
   five-year period ending on the date of the Closing.

      5.18. Employee Relations. As of June 30, 2003, ViaCell and the ViaCell
   Subsidiaries collectively employed an aggregate of approximately 229
   full-time equivalent employees and generally enjoy a good employer-employee
   relationship with its employees. True and complete information relating to
   the key employees of ViaCell (including name and title) for the last two
   years has been made available to the Sellers. None of such key employees has
   given, as of the date hereof, formal notice of an intention to leave
   ViaCell's employ before or after the Closing. ViaCell is not delinquent in
   payments to any of its respective employees or consultants for any wages,
   salaries, commissions, bonuses or other direct compensation for any services
   performed by such party to the date hereof or amounts required to be
   reimbursed to such employees. Upon termination of the employment of any said
   employees, ViaCell will not by reason of anything done prior to the Closing
   be liable to any of said employees or consultants for severance pay or any
   other payments (other than accrued salary, vacation or sick pay in accordance
   with ViaCell's normal policies and reasonable compensation if termination
   occurs other than following notice).

      5.19. Insurance. Schedule 5.19 sets forth a list of all policies or
   binders of fire, liability, product liability, workmen's compensation,
   vehicular, directors and officers and other insurance held by or on behalf of
   ViaCell and each ViaCell Subsidiary. Such policies and binders are in full
   force and effect, are reasonably believed to be adequate for the business
   engaged in by ViaCell and each ViaCell Subsidiary and are in conformity with
   the requirements of all leases to which ViaCell or any ViaCell Subsidiary is
   a party and to the best knowledge of ViaCell, are valid and enforceable in
   accordance with their terms. Neither ViaCell nor any ViaCell Subsidiary is in
   default with respect to any provision contained in any such policy or binder
   nor has ViaCell or any ViaCell Subsidiary failed to give any notice or
   present any claim under any such policy or binder in due and timely fashion.
   There are no outstanding unpaid claims under any such policy or binder.
   Neither ViaCell nor any ViaCell Subsidiary has received notice of
   cancellation or non renewal of any such policy or binder.

      5.20. Environmental Compliance. ViaCell and each ViaCell Subsidiary (a) is
   presently in material compliance with all federal, state, and local
   environmental and health and safety laws, rules, regulations, ordinances,
   guidelines, codes, orders, approvals, and bylaws and similar items applicable
   to its business and properties; (b) has not generated, manufactured,


                                      -39-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

   used, refined, transported, treated, stored, handled, disposed of,
   transferred, produced, or processed any pollutant, biomedical waste, toxic
   substance, hazardous waste, hazardous substance, hazardous material, oil, or
   petroleum product as defined under any Environmental Law, other than ordinary
   household cleaning and other similar products, and has no knowledge of the
   release or threat of release of any Hazardous Substances from its products,
   properties or facilities except in compliance with law; (c) has not (i)
   entered into or been subject to any consent decree, compliance order, or
   administrative order with respect to any environmental or health or safety
   matter relating to its business or any of its properties or facilities, (ii)
   received written notice under the citizen suit provision of any Environmental
   Law in connection with its business or any of its properties or facilities,
   (iii) received any request for information, written notice, demand letter,
   administrative inquiry, or formal or informal complaint or claim with respect
   to any environmental or health or safety matter relating to its business or
   any of its properties or facilities; or (iv) been subject to or threatened
   with any governmental or citizen enforcement action with respect to any
   environmental or health and safety matter relating to its business or any of
   its properties or facilities, and to the best knowledge of ViaCell, has no
   reason to believe that any matters described in (i) (iv) above will be
   forthcoming. No lien has been imposed on any of the properties or facilities
   of ViaCell or any ViaCell Subsidiary by any governmental agency in connection
   with the presence of any Hazardous Substances.

      5.21. Bank Accounts and Powers of Attorney. Schedule 5.21 identifies all
   bank accounts used in connection with the operations of ViaCell and each
   ViaCell Subsidiary whether or not such accounts are held in the name of
   ViaCell or a ViaCell Subsidiary, lists the respective signatories therefor
   and lists the names of all persons holding a power of attorney from ViaCell
   and a summary statement of the terms thereof. Except as set forth on Schedule
   5.21, neither ViaCell nor any ViaCell Subsidiary has granted powers of
   attorney to any person or entity.

      5.22. Brokerage. No broker, finder, agent or similar intermediary has
   acted on behalf of ViaCell in connection with this Agreement or the
   Contemplated Transactions, and there are no brokerage commissions, finders'
   fees or similar fees or commissions payable in connection therewith based on
   any agreement, arrangement or understanding with ViaCell, or any action taken
   by it.

      5.23. Investment Company Act.  ViaCell is not an "investment
   company," or a company "controlled" by an "investment," within the
   meaning of the Investment Company Act of 1940, as amended.

      5.24. Full Disclosure. The representations and warranties of ViaCell
   contained in this Agreement (including, without limitation, the Schedules
   hereto), the Ancillary Agreements and any other agreement, certificate or
   document furnished by or on behalf of ViaCell pursuant to this Agreement do
   not contain any untrue statement of a material fact, or when taken as a
   whole, omit to state a material fact necessary in order to make such
   representations, warranties and statements not misleading. There is no fact
   known to ViaCell that has not been disclosed to the Sellers in this Agreement
   and the Schedules hereto or other documents, certificates or statements
   furnished to the Company hereto that materially


                                      -40-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

   adversely affects, or (in the reasonable business judgment of ViaCell based
   on facts of which it has knowledge) is reasonably likely to have a Material
   Adverse Effect.

      5.25. Financial. As of March 31, 2003, ViaCell had cash of $29.5 million.

   6.   COVENANTS OF THE COMPANY AND THE SELLERS.

      6.1. Closing. The Company and the Sellers, as the case may be, will take
   all of the actions and deliver all the various certificates, documents and
   instruments described in Section 8 as being performed or delivered by the
   Company or the Sellers, respectively.

      6.2. Expenses. With respect to the costs and expenses (including legal,
   accounting, consulting, advisory and brokerage) incurred in connection with
   the Contemplated Transactions (the "Transaction Expenses"), ViaCell, the
   Company and the Sellers shall each bear their own expenses incurred in
   connection with the negotiation, execution and performance of this Agreement
   and the Ancillary Agreements, provided, however, that the Transaction
   Expenses listed in the Transaction Fee Statement as expenses of the Sellers
   shall be borne by the Sellers and paid by the Company as such Seller's agent
   pursuant to Section 2.6.6.

      6.3. Sellers' Release. Except as set forth in Schedule 6.3, effective as
   of the Closing, each Seller hereby releases, remises and forever discharges
   any and all rights and claims that it has had, now has or might now have
   against the Company.

      6.4. Confidentiality.

         6.4.1. Confidentiality of the Sellers. Each Seller acknowledges that
      the success of the Company after the Closing depends upon the continued
      preservation of the confidentiality of certain information possessed by
      such Seller, that the preservation of the confidentiality of such
      information by such Seller is an essential premise of the bargain between
      the Sellers and ViaCell, and that ViaCell would be unwilling to enter into
      this Agreement in the absence of this Section 6.4.1 Accordingly, each
      Seller hereby agrees with ViaCell that such Seller and its Representatives
      will not, and that such Seller will cause its Affiliates not to, at any
      time on or after the Closing Date, directly or indirectly, without the
      prior written consent of ViaCell, disclose or use, any confidential or
      proprietary information involving or relating to the Business or the
      Company or the business of ViaCell; provided, however, that the
      information subject to the foregoing provisions of this sentence will not
      include any information generally available to, or known by, the public
      (other than as a result of disclosure in violation hereof); and provided,
      further, that the provisions of this Section 6.4.1 will not prohibit any
      retention of copies of records or disclosure (a) required by any
      applicable Legal Requirement so long as reasonable prior notice is given
      of such disclosure and a reasonable opportunity is afforded to contest the
      same or (b) made in connection with the enforcement of any right or remedy
      relating to this Agreement or the Contemplated Transactions. The Sellers
      agree that they will be responsible for any breach or violation of the
      provisions of this Section 6.4.1 by any of their Representatives.


                                      -41-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

      6.5. Further Assurances; Obligation to Satisfy Closing Conditions. From
   and after the Closing Date, upon the request of ViaCell, the Company and the
   Sellers will do, execute, acknowledge and deliver all such further acts,
   assurances, deeds, assignments, transfers, conveyances and other instruments
   and papers as may be reasonably required or appropriate or as may be
   reasonably requested by ViaCell to carry out the Contemplated Transactions.
   No Seller will take any action that is designed or intended to have the
   effect of discouraging any lessor, licensor, supplier, distributor, customer
   or employee of the Company or other Person with whom the Company has a
   relationship from maintaining the same relationship with the Company after
   the Closing as it maintained prior to the Closing. Each Seller will refer all
   customer inquiries relating to the Business to ViaCell, or the Company, as
   appropriate, from and after the Closing. Each party, after the date of
   execution of this Agreement until the Closing Date, will use best efforts to
   cause all closing conditions as specified in Sections 8 and 9 of this
   Agreement to be satisfied as soon as practicable.

   7.   COVENANTS OF VIACELL.

      7.1. Financing. ViaCell will use its best efforts to complete the
   Financing prior to the Closing Date on the basis of the Series J Agreements
   delivered in draft form to the Company prior to the date of this Agreement.

      7.2. Company Employee Retention. All employment agreements to which the
   Company is a party will remain in effect in accordance with their terms
   following the Closing. All employees of the Company will be eligible,
   following the Closing, to participate in the ViaCell 1998 Amended and
   Restated Equity Incentive Plan (the "ViaCell Option Plan") at the discretion
   of the Board of Directors of ViaCell. Following the Closing, for purposes of
   participation in the ViaCell Option Plan and other benefit plans, ViaCell
   will treat service by all current Company employees as service with ViaCell
   for the same length of time.

      7.3. New Company Employment Contracts. The Company and/or ViaCell will
   offer Christian van den Bos, Jurgen Peter, and Dr. Stephen Wnendt new
   employment agreements in the form attached hereto as Exhibit I with the
   Company or ViaCell providing salary, bonus, employee benefits and equity
   participation commensurate with their existing positions and functions and
   consistent with ViaCell's employment policies generally, all in accordance
   with applicable German law.

         7.3.1. Dr. Stephan Wnendt. In addition to Dr. Wnendt's new employment
      contract with the Company or ViaCell, after the Closing, ViaCell will
      appoint Dr. Wnendt to its executive management team to serve at the
      discretion of ViaCell's Board of Directors for such period of time that
      Dr. Wnendt remains an employee of the Company or ViaCell.

      7.4. Consultancy Arrangements. The consultancy arrangements between the
   Company and each of Professor Peter Wernet, Dr. Gesine Kogler, Dr. Johannes
   Fischer and Professor R. Krauspe will remain in effect following the Closing
   in accordance with their terms.


                                      -42-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

         7.4.1. Professor Wernet. In the event that, within three years of the
      Closing, (a) ViaCell does not complete a Qualified Public Offering or (b)
      a Change of Control does not occur, ViaCell will at that time offer
      Professor Wernet a full-time employment position in a capacity
      commensurate with his experience and scientific expertise, upon terms and
      conditions to be agreed upon by the parties; provided that, ViaCell shall
      not have an obligation to offer Professor Wernet full time employment if
      he has at any time been in breach of his consultancy agreement with the
      Company or ViaCell. In addition, following the Closing, Professor Wernet
      will become an advisor to ViaCell's executive management team.

      7.5. Advisory Board Position. Following the Closing, ViaCell will appoint
   Professor Wernet as co-chairman of its general Medical and Scientific
   Advisory Board ("MSAB") for a term in accordance with ViaCell's standard
   agreement. Dr. Wernet will be compensated on the same terms and conditions as
   the current chairman of the ViaCell's MSAB.

      7.6. USSC Technology Committee. Following the Closing, ViaCell will
   establish a "USSC Technology Committee" consisting of certain designated
   employees of ViaCell, including Professor Wernet and Dr. Stephan Wnendt. Such
   committee will monitor ViaCell's future activities related to the research
   and development of USSC-based products, and will make, at least
   semi-annually, recommendations to ViaCell's executive management team
   concerning the commercial and scientific viability of such USSC Company
   Products. ViaCell may terminate the activities of the USSC Technology
   Committee at any time following the Closing Date as it may determine in its
   reasonable business judgment, provided that the Committee shall not be
   terminated while the USSC Company Products are being actively developed and
   the Milestones can be achieved.

      7.7. European Operations. Subject to the provisions of this Section, after
   the Closing and through the second anniversary thereof, ViaCell will continue
   the Company's operations at its current facility in Langenfeld, Germany. To
   the extent practicable, ViaCell will utilize such facilities as the
   headquarters for ViaCell's business activities in Europe for both private
   umbilical cord blood banking and research and development in therapeutic
   applications of stem cell technologies. Notwithstanding the foregoing,
   ViaCell may, in its prudent business judgment, decide whether and at what
   level to continue the Company's current operations in Langenfeld, Germany.
   Should such European operations be discontinued by ViaCell, ViaCell will
   continue the current research and development of any USCC Company Products
   for purposes of achieving the Milestones to the extent required by Section
   7.8 at any location deemed suitable by ViaCell.

      7.8. Milestones. ViaCell will use its best efforts commensurate with the
   value of the USSC Company Programs in light of the other activities being
   conducted by ViaCell, including the provision of funds, to achieve the
   Milestones, subject to any reasonable determination by ViaCell, after due
   consideration of the recommendation of the USSC Technology Committee, that
   the development programs of the USSC Company Products should be suspended or
   discontinued for a business or scientific reason, including without
   limitation ViaCell's prioritization of its research and development programs
   and its research and development budget.


                                      -43-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

      7.9. Institutional Obligations. Following the Closing, ViaCell will assume
   the Company's financial obligations to the Heinrich Heine University of
   Dusseldorf.

      7.10. Change of Control. No Change of Control transaction of ViaCell shall
   be effective unless the successor to ViaCell assumes the obligations of
   ViaCell in connection with the Contemplated Transactions and under this
   Agreement; provided, however, that Section 7.2, Section 7.3, Section 7.4 and
   Section 7.5 shall all terminate upon a Change of Control.

   8.   CONDITIONS TO VIACELL'S OBLIGATIONS AT THE CLOSING.

    The obligations of ViaCell to consummate the Closing are subject to the
fulfillment of each of the following conditions unless waived by ViaCell in
accordance with Section 12.3:

      8.1. Representations and Warranties. The representations and warranties of
   the Company and the Sellers contained in this Agreement and in any document,
   instrument or certificate delivered hereunder (a) that are not qualified by
   materiality or Material Adverse Effect will be true and correct in all
   material respects at and as of the Closing with the same force and effect as
   if made as of the Closing, and (b) that are qualified by materiality or
   Material Adverse Effect will be true and correct in all respects at and as of
   the Closing with the same force and effect as if made as of the Closing, in
   each case, other than representations and warranties that expressly speak
   only as of a specific date or time, which will be true and correct as of such
   specified date or time.

      8.2. Performance. The Company and each Seller will have performed and
   complied in all material respects, with all agreements, obligations and
   covenants contained in this Agreement that are required to be performed or
   complied with by them at or prior to the Closing.

      8.3. Stock and Option Certificates.

         8.3.1. Series A Shares. The Series A Sellers will have delivered to
      ViaCell certificates evidencing the assignment of all of the Series A
      Shares substantially in the form of Assignment attached hereto as Exhibit
      H.

         8.3.2. Common Shares. The Common Sellers will have delivered to ViaCell
      certificates evidencing the assignment of all of the Common Shares
      substantially in the form of Assignment attached hereto as Exhibit H.

         8.3.3. Company Options. The Company Option Holders will have delivered
      to ViaCell waivers of any entitlement to receive Company Options.

         8.3.4. Series I Agreements. The Sellers will, prior to or at the
      Closing, have executed and become parties to all of the Series I
      Agreements or amendments thereto.

         8.3.5. Share Register. The Company will have delivered to ViaCell an
      updated excerpt of the share register of the Company stating that ViaCell
      is the holder of all Shares of the Company.


                                      -44-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

      8.4. Qualifications. No provision of any applicable Legal Requirement and
   no Government Order will prohibit the consummation of any of the Contemplated
   Transactions.

      8.5. Absence of Litigation. No Action will be pending or threatened in
   writing which may result in a Governmental Order (nor will there be any
   Governmental Order in effect) (a) which would prevent consummation of any of
   the Contemplated Transactions, (b) which would result in any of the
   Contemplated Transactions being rescinded following consummation, (c) which
   would limit or otherwise adversely affect the right of ViaCell to own the
   Shares (including the right to vote the Shares), to control the Company, or
   to operate all or any material portion of either the Business or Assets of
   the Company or of the business or assets of ViaCell or any of its Affiliates
   or (d) would compel ViaCell or any of its Affiliates to dispose of all or any
   material portion of either the Business or Assets of the Company or the
   business or assets of ViaCell or any of its Affiliates.

      8.6. Legal Opinion. ViaCell will have received from Sernetz-Schafer,
   counsel to the Company (or other counsel reasonably acceptable to ViaCell),
   its opinion with respect to the Contemplated Transactions, which opinion will
   be in the form attached hereto as Exhibit C.

      8.7. Consents, etc. All actions by (including any authorization, consent
   or approval) or in respect of (including notice to), or filings with, any
   Governmental Authority or other Person that are required to consummate the
   Contemplated Transactions, as disclosed in Schedule 3.6, Schedule 4.2 and
   Schedule 5.9 or as otherwise required by law, will have been obtained or
   made, in a manner reasonably satisfactory in form and substance to ViaCell,
   and no such authorization, consent or approval will have been revoked.

      8.8. Stockholder Approval. ViaCell will have received the consents of its
   stockholders required to consummate the Contemplated Transactions.

      8.9. Proceedings and Documents. All corporate and other proceedings in
   connection with the Contemplated Transactions and all documents incident
   thereto will be reasonably satisfactory in form and substance to ViaCell and
   its counsel, and they will have received all such counterpart original and
   certified or other copies of such documents as they may reasonably request.

      8.10. Ancillary Agreements.  Each of the Ancillary Agreements will
   have been executed and delivered to ViaCell by each of the other
   parties thereto.

      8.11. Financing.  ViaCell will have closed on an offering of not
   less than $10 million in new equity capital to be received in cash
   pursuant to the private placement of its Series J Convertible Preferred
   Stock at a price of at least $8 per share.

      8.12. No Material Adverse Change.  Since June 30, 2003, there will
   have occurred no events nor will there exist circumstances that have
   resulted in a Material Adverse Effect on the Company.

      8.13. Compliance Certificate.  The Company will have delivered to
   ViaCell a certificate substantially in the form of Exhibit D.


                                      -45-
<PAGE>
      8.14. Initial Budget. The Initial Budget attached hereto as Exhibit F will
   have been completed, approved and adopted by ViaCell.

      8.15. Company Employee Contracts. Dr. Wnendt, Jurgen Peter and Dr.
   Christian van den Bos will have executed employment agreements with the
   Company or ViaCell in the form attached hereto as Exhibit I.

      8.16. Resignations. ViaCell shall have received letters of resignation
   from each current member of the Company's Supervisory Board, effective upon
   the Closing.

      8.17. Supporting Documents. ViaCell shall have received the following:

            (a) Certified excerpt of the Commercial Register of the Company
         issued at most five (5) days prior to Closing;

            (b) Copies of the resolution of the Supervisory Board of the Company
         ("Aufsichtsrat") notified by the Managing Director of the Company,
         authorizing and approving the assignment of the Shares pursuant to
         Article 6 subsection 3 of the Company's Articles of Association; and

            (c) A certificate executed by the Managing Director of the Company
         certifying (1) the due authorization of the resolution referred to in
         subparagraph (b) above, (2) the names, titles and signatures of the
         officers authorized to execute the documents referred to in
         subparagraph (b) above, and (3) that the Company's Organizational
         Documents have not been amended, modified or supplemented in any way.

      8.18. Net Working Capital and Transaction Fees. The Company shall have
   delivered, at least three (3) Business Days prior to the Closing Date, the
   Closing Date Net Working Capital Statement to ViaCell which statement shall
   be attached hereto as Exhibit G, and the Transaction Fee Statement, which
   statement shall be attached hereto as Exhibit L.

   9.   CONDITIONS TO THE COMPANY AND THE SELLERS' OBLIGATIONS AT THE
CLOSING.

    The obligations of the Company and the Sellers to consummate the Closing is
subject to the fulfillment of each of the following conditions (unless waived by
the Company or Sellers in accordance with Section 12.4):

      9.1. Representations and Warranties. The representations and warranties of
   ViaCell contained in this Agreement and in any document, instrument or
   certificate delivered hereunder (a) that are not qualified by materiality or
   Material Adverse Effect will be true and correct in all material respects at
   and as of the Closing with the same force and effect as if made as of the
   Closing and (b) that are qualified by materiality or Material Adverse Effect
   will be true and correct in all respects at and as of the Closing with the
   same force and effect as if made as of the Closing, in each case, other than
   representations and warranties that expressly speak only as of a specific
   date or time, which will be true and correct as of such specified date or
   time.


                                      -46-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

      9.2. Performance. ViaCell will have performed and complied with, in all
   material respects, all agreements, obligations and covenants contained in
   this Agreement and the Ancillary Agreements that are required to be performed
   or complied with by ViaCell at or prior to the Closing.

      9.3. Qualifications. No provision of any applicable Legal Requirement and
   no Government Order will prohibit the consummation of any of the Contemplated
   Transactions.

      9.4. Absence of Litigation. No Action will be pending or threatened in
   writing which may result in Governmental Order, nor will there be any
   Governmental Order in effect, (a) which would prevent consummation of any of
   the Contemplated Transactions or (b) which would result in any of the
   Contemplated Transactions being rescinded following consummation (and no such
   Governmental Order will be in effect).

      9.5. Legal Opinion. The Company and the Sellers will have received from
   Ropes & Gray LLP, counsel to ViaCell, its opinion with respect to the
   Contemplated Transactions, which opinion will be in the form attached hereto
   as Exhibit E.

      9.6. Consents, etc. All actions by (including any authorization, consent
   or approval) or in respect of (including notice to), or filings with, any
   Governmental Authority or other Person that are required to consummate the
   Contemplated Transactions, will have been obtained or made, in a manner
   reasonably satisfactory in form and substance to the Sellers, and no such
   authorization, consent or approval will have been revoked.

      9.7. Proceedings and Documents. All corporate and other proceedings in
   connection with the Contemplated Transactions and all documents incident
   thereto will be reasonably satisfactory in form and substance to the Sellers
   and to their counsel, and the Sellers will have received all such counterpart
   original and certified or other copies of such documents as they may
   reasonably request.

      9.8. Note Escrow Agreement. The Note Escrow Agreement will have been
   executed by the parties thereto and $4.2 million deposited with the Note
   Escrow Agent in accordance with the terms of that agreement which is attached
   hereto as Exhibit K.

      9.9. Series I Agreements. ViaCell will have delivered to the Sellers its
   executed counterpart signature page to the Series I Agreements.

      9.10. Ancillary Agreements. Each of the Ancillary Agreements to which
   ViaCell is a party will have been executed and delivered to the Company and
   the Sellers by each of the other parties thereto.

      9.11. No Material Adverse Change. Since the ViaCell Balance Sheet Date,
   there will have occurred no events nor will there exist circumstances which
   singly or in the aggregate have resulted in a Material Adverse Effect.

      9.12. Stock Certificates.


                                      -47-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

         9.12.1. Series I Shares. ViaCell will have delivered to the Series A
      Sellers and the Common Sellers Series I Stock certificates evidencing the
      number of shares of Series I Stock set forth opposite each Seller's name
      on Schedule 1 and Schedule 2, respectively.

         9.12.2. Escrowed Shares. ViaCell will have delivered the Escrowed
      Shares to the Escrow Agent.

      9.13. Compliance Certificate.  ViaCell will have delivered to the
   Company and the Sellers a certificate substantially in the form of
   Exhibit D.

      9.14. Financing. ViaCell will have closed on an offering of not less than
   $10 million in new equity capital to be received in cash pursuant to the
   private placement of its Series J Convertible Preferred Stock at a price of
   at least $8.00 per share on the basis of the Series J Agreements in the
   version delivered to the Company prior to the date of this Agreement.

      9.15. Initial Budget.  The Initial Budget attached hereto as Exhibit
   F will have been completed, approved and adopted by ViaCell.

      9.16. Supporting Documents.  The Sellers shall have received the
   following:

            (a) Certificate of good standing of ViaCell, certified by the
         Delaware Secretary of State;

            (b) Copies of resolutions of the Board of Directors of ViaCell and
         of the stockholders of ViaCell, certified by the Secretary of ViaCell,
         authorizing and approving the execution, delivery and performance of
         this Agreement, all Ancillary Agreements, and all other documents and
         instruments to be delivered pursuant hereto and thereto; and

            (c) Certificates executed by the Secretary of ViaCell certifying (1)
         the due authorization of the resolutions referred to in subparagraph
         (b) above, (2) the names, titles and signatures of the officers
         authorized to execute the documents referred to in subparagraph (b)
         above, and (3) that the Articles and the Bylaws of the Company have not
         been amended, modified or supplemented in any way.

   10.  TERMINATION.

      10.1. Termination of Agreement.  This Agreement may be terminated
   (the date on which the Agreement is terminated, the "Termination Date")
   at any time prior to the Closing:

         (a) by mutual written consent of ViaCell, the Company, the Seller's
      Representative and the MPM Sellers;

         (b) by either ViaCell or the Company if a final nonappealable
      Governmental Order permanently enjoining, restraining or otherwise
      prohibiting the Closing will have been issued by a Governmental Authority
      of competent jurisdiction;


                                      -48-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

         (c) by ViaCell if either (i) there will be a material breach of, or
      material inaccuracy in, any representation or warranty of the Company or
      any of the Sellers contained in this Agreement as of the date of this
      Agreement (other than representations or warranties that expressly speak
      only as of a specific date or time, with respect to which ViaCell's right
      to terminate will arise only in the event of a breach of, or inaccuracy
      in, such representation or warranty as of such specified date or time), or
      (ii) the Company or a Seller will have breached or violated in any
      material respect any of their respective covenants and agreements
      contained in this Agreement; in either case which breach remains uncured
      for ten (10) business days following notice by ViaCell to the Company; or

         (d) by the Company if either (i) there will be a material breach of, or
      material inaccuracy in, any representation or warranty of ViaCell
      contained in this Agreement as of the date of this Agreement (other than
      representations or warranties that expressly speak only as of a specific
      date or time, with respect to which the Company's right to terminate will
      arise only in the event of a breach of, or inaccuracy in, such
      representation or warranty as of such specified date or time), or (ii)
      ViaCell will have breached or violated in any material respect any of its
      covenants and agreements contained in this Agreement; in either case which
      breach remains uncured for ten (10) Business Days following notice by the
      Company to ViaCell.

      10.2. Effect of Termination. In the event of the termination of this
   Agreement pursuant to Section 10.1, this Agreement - other than the
   provisions of Sections 6.2 (Expenses), 6.4 (Confidentiality), 12.11
   (Governing Law), and 12.12 (Dispute Resolution) - will then be null and void
   and have no further force and effect and all other rights and Liabilities of
   the parties hereunder will terminate without any Liability of any party to
   any other party, except for Liabilities arising in respect of breaches under
   this Agreement by any party on or prior to the Termination Date.

   11.  INDEMNIFICATION.

      11.1. Indemnification by the Sellers.

         11.1.1. Indemnification. Subject to the limitations set forth in this
      Section 11, each Seller will severally (but not jointly) indemnify and
      hold harmless ViaCell and each of its Affiliates (including, following the
      Closing, the Company), and the Representatives and Affiliates of each of
      the foregoing Persons (each, a "ViaCell Indemnified Person"), from,
      against and in respect of any and all Actions, Liabilities, Governmental
      Orders, Encumbrances, losses, damages, bonds, dues, assessments, fines,
      penalties, Taxes, fees, costs (including costs of investigation, defense
      and enforcement of this Agreement), expenses or amounts paid in settlement
      (in each case, including reasonable attorneys' and experts fees and
      expenses), whether or not involving a Third Party Claim (collectively,
      "Losses"), incurred or suffered by ViaCell Indemnified Persons or any of
      them as a result of, arising out of or directly or indirectly relating to:

            (a) any fraud of such Seller or the Company or any breach of, or
         inaccuracy in, any representation or warranty made by the Company or
         such Seller in (i) this Agreement (other than in Section 3), (ii) any
         Schedule to this Agreement, (iii) any


                                      -49-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

         instrument of transfer or certificate required to be delivered pursuant
         to this Agreement, or (iv) the documents required to be delivered
         pursuant to Section 8.3.3, Section 8.16 and Section 8.18 of this
         Agreement; or

            (b) any breach or violation of any covenant or agreement of the
         Company contained in this Agreement to the extent required to be
         performed or complied with by the Company prior to the Closing pursuant
         to this Agreement; or

            (c) any fraud by the Company, or any breach of, or inaccuracy in,
         any representation or warranty made by the Company in Section 3; or

            (d) any breach or violation of any covenant or agreement of such
         Seller (including under this Section 11) set forth in this Agreement.

         11.1.2. Monetary Limitations. The Sellers will have no obligation to
      indemnify ViaCell Indemnified Persons pursuant to Sections 11.1.1(a) and
      11.1.1(c) in respect of Losses arising from the breach of, or inaccuracy
      in, any representation or warranty described therein, and (ii) Sections
      11.1.1(b) and 11.1.1(d) in respect of Losses arising from a breach or
      violation of any covenant or agreement described therein unless the
      aggregate amount of all such Losses incurred or suffered by ViaCell
      Indemnified Persons exceeds $150,000 (at which point the Sellers will
      indemnify ViaCell Indemnified Persons for all such Losses), and the
      Sellers' aggregate liability in respect of claims for indemnification
      pursuant to Section 11.1.1(a) through 11.1.1(d), other than in respect of
      claims based on conduct constituting fraud, fraud in the inducement,
      intentional misrepresentation or claims based on breaches of Sections 6.4
      or 6.5 of this Agreement, will not exceed fifty percent (50%) of the value
      of all shares of Series I Stock issued at Closing pursuant to Sections 2.1
      and 2.2 hereof, plus 50% of the value of the initial number of Contingent
      Shares (with each such share under Sections 2.1, 2.2 and 2.3 valued at
      $8.00) (the "Cap"); provided that, the Cap shall be reduced by 50% of the
      value of the Escrowed Shares and the Contingent Shares (valued at $8.00
      per share) upon termination of the escrow and the obligation to issue the
      Contingent Shares as described in Sections 2.2.3 and 2.3.3. Each Seller's
      several liability shall not, with respect to any and all claims brought
      under this Section 11 for Losses, exceed such Seller's proportionate share
      of the Cap, based on the total amount of consideration potentially payable
      to such Seller pursuant to Section 2.1 through Section 2.4 of this
      Agreement and with respect to each such claim for Losses, each Seller's
      several liability shall not exceed the percentage of such claim for Losses
      that is equal to such Seller's percentage share of the Cap, based on the
      total amount of consideration potentially payable to such Seller pursuant
      to Sections 2.1 through 2.4 of this Agreement; provided further, that in
      no event shall any Seller be required to indemnify any ViaCell Indemnified
      Person against any Losses arising out of fraud or intentional
      misrepresentation by, or breach of any representation, warranty, covenant
      or agreement of, any other Seller.

      11.2. Time for Claims. No claim may be made or suit instituted seeking
   indemnification pursuant to Section 11.1.1(a) through 11.1.1(d) unless a
   written notice describing such breach or inaccuracy or violation in
   reasonable detail in light of the


                                      -50-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

   circumstances then known to the ViaCell Indemnified Party is provided to the
   Indemnifying Party within eighteen (18) months after the Closing Date.

      11.3. Third Party Claims.

         11.3.1. Notice of Claim. If any third party will notify an Indemnified
      Party with respect to any matter (a "Third Party Claim") which may give
      rise to an Indemnified Claim against an Indemnifying Party under Section
      11.1 and Section 11.2, then the Indemnified Party will promptly give
      written notice to the Indemnifying Party; provided, however, that no delay
      on the part of the Indemnified Party in notifying the Indemnifying Party
      will relieve the Indemnifying Party from any obligation under this Section
      11, except to the extent such delay actually and materially prejudices the
      Indemnifying Party. For the avoidance of doubt, each Third Party Claim
      shall be subject to the limitations set forth in this Section 11.

         11.3.2. Assumption of Defense, etc. The Indemnifying Party will be
      entitled to participate in the defense of any Third Party Claim that is
      the subject of a notice given by the Indemnified Party pursuant to Section
      11.3.1. In addition, the Indemnifying Party will have the right to defend
      the Indemnified Party against the Third Party Claim with counsel of its
      choice reasonably satisfactory to the Indemnified Party so long as (a) the
      Indemnifying Party gives written notice to the Indemnified Party within
      fifteen days after the Indemnified Party has given notice of the Third
      Party Claim that the Indemnifying Party will indemnify the Indemnified
      Party from and against the entirety of any and all Losses the Indemnified
      Party may suffer resulting from, arising out of, relating to, in the
      nature of, or caused by the Third Party Claim, (b) the Indemnifying Party
      provides the Indemnified Party with evidence reasonably acceptable to the
      Indemnified Party that the Indemnifying Party will have adequate financial
      resources to defend against the Third Party Claim and fulfill its
      indemnification obligations hereunder, (c) the Third Party Claim involves
      only money damages and does not seek an injunction or other equitable
      relief against the Indemnified Party, (d) the Indemnified Party has not
      been advised by counsel that an actual or potential conflict exists
      between the Indemnified Party and the Indemnifying Party in connection
      with the defense of the Third Party Claim, (e) the Third Party Claim does
      not relate to or otherwise arise in connection with Taxes or any criminal
      or regulatory enforcement Action, (f) settlement of, an adverse judgment
      with respect to or the Indemnifying Party's conduct of the defense of the
      Third Party Claim is not, in the good faith judgment of the Indemnified
      Party, likely to be adverse to the Indemnified Party's reputation or
      continuing business interests (including its relationships with current or
      potential customers, suppliers or other parties material to the conduct of
      its business) and (g) the Indemnifying Party conducts the defense of the
      Third Party Claim actively and diligently. The Indemnified Party may
      retain separate co-counsel at its sole cost and expense and participate in
      the defense of the Third Party Claim; provided, however, that the
      Indemnifying Party will pay the fees and expenses of separate co-counsel
      retained by the Indemnified Party that are incurred prior to Indemnifying
      Party's assumption of control of the defense of the Third Party Claim.

         11.3.3. Limitations on Indemnifying Party. The Indemnifying Party will
      not consent to the entry of any judgment or enter into any compromise or
      settlement with


                                      -51-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

      respect to the Third Party Claim without the prior written consent of the
      Indemnified Party unless such judgment, compromise or settlement (a)
      provides for the payment by the Indemnifying Party of money as sole relief
      for the claimant, (b) results in the full and general release of the
      ViaCell Indemnified Persons from all liabilities arising or relating to,
      or in connection with, the Third Party Claim and (c) involves no finding
      or admission of any violation of Legal Requirements or the rights of any
      Person and no effect on any other claims that may be made against the
      Indemnified Party.

         11.3.4. Indemnified Party's Control. If the Indemnifying Party does not
      deliver the notice contemplated by clause (a), or the evidence
      contemplated by clause (b), of Section 11.3.2 within 15 days after the
      Indemnified Party has given notice of the Third Party Claim, or otherwise
      at any time fails to conduct the defense of the Third Party Claim actively
      and diligently, the Indemnified Party may defend, and may consent to the
      entry of any judgment or enter into any compromise or settlement with
      respect to, the Third Party Claim in any manner it may reasonably deem
      appropriate (and the Indemnified Party need not consult with, or obtain
      any consent from, the Indemnifying Party in connection therewith). If such
      notice and evidence is given on a timely basis and the Indemnifying Party
      conducts the defense of the Third Party Claim actively and diligently but
      any of the other conditions in Section 11.3.2 is or becomes unsatisfied,
      the Indemnified Party may defend, and may consent to the entry of any
      judgment or enter into any compromise or settlement with respect to, the
      Third Party Claim; provided, however, that the Indemnifying Party will not
      be bound by the entry of any such judgment consented to, or any such
      compromise or settlement effected, without its prior written consent
      (which consent will not be unreasonably withheld or delayed). In the event
      that the Indemnified Party conducts the defense of the Third Party Claim
      pursuant to this Section 11.3.4, the Indemnifying Party will (a) advance
      the Indemnified Party promptly and periodically for the costs of defending
      against the Third Party Claim (including reasonable attorneys' fees and
      expenses) and (b) remain responsible for any and all other Losses that the
      Indemnified Party may incur or suffer resulting from, arising out of,
      relating to, in the nature of or caused by the Third Party Claim to the
      fullest extent provided in this Section 11.

         11.3.5. Consent to Jurisdiction Regarding Third Party Claim. The
      Sellers, each in its capacity as an Indemnifying Party, hereby consents to
      the non-exclusive jurisdiction of any court in which any Third Party Claim
      may be brought against any Indemnified Party for purposes of any claim
      which such Indemnified Party may have against such Indemnifying Party
      pursuant to this Agreement in connection with such Third Party Claim, and
      in furtherance thereof, the provisions of Section 12.12 are incorporated
      herein by reference, mutatis mutandis.

      11.4. No Circular Recovery. With respect to any claim brought by a ViaCell
   Indemnified Person against any Seller relating to this Agreement and any of
   the Contemplated Transactions, each Seller expressly waives any right of
   subrogation, contribution, advancement, indemnification or other claim
   against the Company with respect to any amounts owed by such Seller pursuant
   to this Section 11.


                                      -52-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

      11.5. Indemnity Escrow; Calculation of Several Liability.  Any
   Indemnity Claim for Losses pursuant to this Section 11 shall be
   satisfied in the following manner subject to the Cap set forth in
   Section 11.1.2:

         (a) 81.25% of such Indemnity Claim shall be paid through the return to
      ViaCell of the Series I Shares paid to the Series A Sellers and the Common
      Sellers at Closing pursuant to Section 2.1 of this Agreement with each
      share valued, for purposes of this Section 11, at $8.00 per share,
      provided that, if ViaCell shall have completed an initial public offering
      prior to the time such shares are returned to satisfy an Indemnity Claim,
      the shares will be valued at the greater of (x) $8.00 per share and (y)
      the then current market price of such stock (calculated as the average
      closing price for the 20 consecutive trading days ending on the second day
      prior to the date such shares are returned) and further provided, that
      each Indemnity Claim satisfied pursuant to this clause shall be allocated
      (i) 51.45% to the Common Sellers on a pro rata basis based on Schedule 2
      hereto and (ii) 48.55% to the Series A Sellers on a pro rata basis based
      on Schedule 1 hereto;

         (b) 8.53% of such Indemnity Claim shall be paid through a reduction of
      the shares of Series I Stock held in escrow pursuant to Section 2.2 of
      this Agreement or a return of such shares following a release from escrow
      with each share valued, for purposes of this Section 11, at $8.00 per
      share, provided that, if ViaCell shall have completed an initial public
      offering prior to the time such Escrowed Shares are reduced to satisfy an
      Indemnity Claim, such shares will be valued at the greater of (x) $8.00
      per share and (y) the then current market price of such stock (calculated
      as the average closing price for the 20 consecutive trading days ending on
      the second day prior to the date such shares are returned) and further
      provided, that each Indemnity Claim satisfied pursuant to this clauses
      shall be allocated to the Common Sellers on a pro rata basis based on
      Schedule 3 hereto;

         (c) 10.22% of such Indemnity Claim shall be paid for as long as there
      are Contingent Shares that have not been issued to the MPM Sellers through
      a pro rata reduction based on Schedule 5 hereto of the total amount of
      Contingent Shares, or a pro rata return of such shares following the
      issuance thereof, with each share valued, for purposes of this Section 11,
      at $8.00 per share, provided that, if ViaCell shall have completed an
      initial public offering prior to the time such shares are returned to
      satisfy an Indemnity Claim, the shares will be valued at the greater of
      (x) $8.00 per share and (y) the then current market price of such stock
      (calculated as the average closing price for the 20 consecutive trading
      days ending on the second day prior to the date such shares are returned);
      and

         (d) in the event that all shares allocable to the Series A Sellers have
      been used to satisfy indemnification claims pursuant to this Section 11 in
      the manner set forth in clauses (a), (b) and (c) above or have been sold
      or otherwise transferred, and there are additional claims against the
      Series A Sellers in accordance with this Section 11, any remaining amounts
      owing on such Indemnity Claim that are allocable to the Series A Sellers
      shall be paid through a pro rata reduction based on Schedule 1 hereto of
      the principal amounts owing under each of the Notes.


                                      -53-
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                                                        Stock Purchase Agreement
                                                              September 30, 2003

         (e) In the event that a Seller has, at the time that an indemnification
      payment is owed hereunder, sold or otherwise transferred all of the shares
      of stock that would otherwise be returned to ViaCell under this Section
      11, such Seller shall be obligated to make such indemnification payment
      that is otherwise not satisfied by a return of shares to ViaCell in cash
      based on a value of $8.00 per share, provided that, if ViaCell shall have
      completed an initial public offering prior to the time such shares would
      have been returned to satisfy an Indemnity Claim, the cash payment will be
      valued at the greater of (x) $8.00 per share and (y) the then current
      market price of such stock (calculated as the average closing price for
      the 20 consecutive trading days ending on the second day prior to the date
      such shares would have been returned). For the avoidance of doubt, no
      Seller shall be required to make any cash payment to satisfy
      indemnification claims hereunder if such claim can be satisfied by the
      return of shares in accordance with the terms of this Section 11.5, and no
      Seller shall be required to satisfy any Indemnification Claim under this
      Agreement other than through the return of shares (or the reduction of
      shares in escrow) if and to the extent that such Seller has not sold or
      transferred its shares, except in the case of the Series A Sellers
      pursuant to clause (d) of this section.

      11.6. Offset. The calculation of any such Loss will reflect the amount of
   any insurance proceeds or recoveries from third parties received in cash by
   the ViaCell Indemnified Persons in respect of such Loss, net of the present
   value of any increase in insurance premiums or other charges paid or to be
   paid by the ViaCell Indemnified Persons resulting from such Loss and all
   costs and expenses incurred by any ViaCell Indemnified Person in recovering
   such proceeds from its insurers or third parties, as applicable.

      11.7. Consequential Damages. In no event shall any of the Indemnifying
   Parties be responsible or liable for any Losses or other amounts under this
   Section 11 that are consequential in the nature of lost profits or punitive
   damages, but the ViaCell Indemnified Persons shall otherwise be entitled to
   indemnification for all other Losses.

      11.8. Knowledge and Investigation.  ViaCell shall not be entitled to
   recover under this Section 11 for matters of which it had actual
   knowledge at Closing.

      11.9. Remedies Cumulative. The rights of each ViaCell Indemnified Person
   under this Section 11 are cumulative, and each ViaCell Indemnified Person
   will have the right in any particular circumstance, in its sole discretion,
   to enforce any provision of this Section 11 without regard to the
   availability of a remedy under any other provision of this Section 11.

      11.10. Exclusive Remedy. Except for remedies that cannot be waived as a
   matter of law or as provided in Section 12.13, if the Closing occurs,
   indemnification pursuant to this Section 11 will be the exclusive remedy of
   ViaCell Indemnified Person for any breach of this Agreement (including any
   representation, warranty, covenant and agreement contained in this
   Agreement), other than in respect of claims based on conduct constituting
   fraud, fraud in the inducement, intentional misrepresentation or claims based
   on breaches of Sections 6.4 or 6.5 of this Agreement; provided however that
   in no circumstances shall any Seller liable to any ViaCell Indemnified Party
   for any amounts in excess of the total consideration actually paid to such
   Seller pursuant to Sections 2.1, 2.2, 2.3 and 2.4 hereof.


                                      -54-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

   12.  MISCELLANEOUS

      12.1. Notices. All notices, requests, demands, claims and other
   communications required or permitted to be delivered, given or otherwise
   provided under this Agreement must be in writing and must be delivered, given
   or otherwise provided:

            (a) by hand (in which case, it will be effective upon delivery); or

            (b) by overnight delivery by a nationally recognized courier service
         (in which case, it will be effective on two Business Days after being
         deposited with such courier service);

    in each case, to the address (or facsimile number) listed below:

      If to the Company, to it at:

            Kourion Therapeutics AG
            Berghausener Strasse 98
            D-40764 Langenfeld, Germany
            Telephone number:  011-49-2173-392-2100
            Facsimile number:  011-49-2173-392-2150
            Attention:  PD Dr. Stephan Wendt

      with a copy to:

            Sernetz-Schafer
            Rechtsanwalte
            Berliner Allee 26
            40212 Dusseldorf
            Telephone number:  011-49-211-836-61-0
            Facsimile number:  011-49-211-836-61-50
            Attention:  Dr. Ulrike Schafer

      If to ViaCell, to it at:

            ViaCell, Inc.
            131 Clarendon Street
            Boston, MA  02116
            Telephone number:  617-266-4373
            Facsimile number:  617-266-9391
            Attention:  Marc D. Beer

      with a copy to:

            Ropes & Gray LLP
            One International Place
            Boston, Massachusetts 02110
            Telephone number:  (617) 951-7000


                                      -55-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

            Facsimile number: (617) 951-7050
            Attention:  Marc A. Rubenstein

      If to the Sellers, to the address listed in Schedule 1 or Schedule 2 to
      this Agreement.

Each of the parties to this Agreement may specify different address or facsimile
number by giving notice in accordance with this Section 12.1 to each of the
other parties hereto.

      12.2. Succession and Assignment; No Third-Party Beneficiary. Subject to
   the immediately following sentence, this Agreement will be binding upon and
   inure to the benefit of the parties hereto and their respective successors
   and permitted assigns, each of which such successors and permitted assigns
   will be deemed to be a party hereto for all purposes hereof. No party may
   assign, delegate or otherwise transfer either this Agreement or any of its
   rights, interests, or obligations hereunder without the prior written
   approval of the other parties which approval shall not be unreasonably
   withheld; provided, however, that ViaCell may (a) assign any or all of its
   rights and interests hereunder to one or more of its Affiliates and (b)
   designate one or more of its Affiliates to perform its obligations hereunder,
   in each case, so long as ViaCell is not relieved of any Liability hereunder.
   Except as expressly provided herein, this Agreement is for the sole benefit
   of the parties and their permitted successors and assignees and nothing
   herein expressed or implied will give or be construed to give any Person,
   other than the parties and such successors and assignees, any legal or
   equitable rights hereunder.

      12.3. Consent of Sellers. Each Seller and the Company hereby consents to
   and approves in all respects the assignment of the Shares to ViaCell as
   contemplated hereby. Each Seller in particular waives (i) any rights of first
   refusal and rights of co-sale it may have, in particular under the
   shareholders agreement dated June 25, 2001, in relation to the sale and
   assignment of the Shares by each Seller to ViaCell under this Agreement, and
   (ii) any rights regarding a restriction on transfer contained in any
   agreements to which the Sellers are a party.

      12.4. Amendments and Waivers. No amendment or waiver of any provision of
   this Agreement will be valid and binding unless it is in writing and signed,
   in the case of an amendment, by ViaCell, the Company and the Sellers, or in
   the case of a waiver, by the party against whom the waiver is to be
   effective. No waiver by any party of any breach or violation or, default
   under or inaccuracy in any representation, warranty or covenant hereunder,
   whether intentional or not, will be deemed to extend to any prior or
   subsequent breach, violation, default of, or inaccuracy in, any such
   representation, warranty or covenant hereunder or affect in any way any
   rights arising by virtue of any prior or subsequent such occurrence. No delay
   or omission on the part of any party in exercising any right, power or remedy
   under this Agreement will operate as a waiver thereof.

      12.5. Provisions Concerning Sellers' Representative.

         12.5.1.  Appointment.  Each Seller hereby appoints Dr. Stephan
      Wnendt as the agent, proxy and attorney-in-fact for such Seller for
      all purposes under this Agreement


                                      -56-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

      (including full power and authority to act on the Sellers' behalf).
      Without limiting the generality of the foregoing, the Sellers'
      Representative will be authorized to:

            (a) in connection with the Closing, execute and receive all
         documents, instruments, certificates, statements and agreements on
         behalf of and in the name of the Sellers necessary to effectuate the
         Closing and consummate the Contemplated Transactions;

            (b) take all actions on behalf of the Sellers in connection with any
         claims made under Section 11 to defend or settle such claims, and to
         make payments in respect of such claims;

            (c) execute and deliver, should it elect to do so in its sole
         discretion, on behalf of the Sellers, any amendment to this Agreement
         so long as such amendment will apply equally to all Sellers; and

            (d) take all other actions to be taken by or on behalf of the
         Sellers and exercise any and all rights which the Sellers are permitted
         or required to do or exercise under this Agreement.

         12.5.2. Liability. The Sellers' Representative will not be liable to
      any Seller for any action taken by it in good faith pursuant to this
      Agreement, and the Sellers will jointly and severally indemnify the
      Sellers' Representative from any Losses arising out of its serving as the
      Sellers' Representative hereunder. The Sellers' Representative is serving
      in that capacity solely for purposes of administrative convenience, and is
      not personally liable in such capacity for any of the obligations of the
      Sellers hereunder, and ViaCell agrees that it will not look to the
      personal assets of the Sellers' Representative, acting in such capacity,
      for the satisfaction of any obligations to be performed by the Sellers
      hereunder.

      12.6. Entire Agreement. This Agreement, together with the other Ancillary
   Agreements and any documents, instruments and certificates explicitly
   referred to herein, constitutes the entire agreement among the parties hereto
   with respect to the subject matter hereof and supersedes any and all prior
   discussions, negotiations, proposals, undertakings, understandings and
   agreements, whether written or oral, with respect thereto.

      12.7. Schedules; Listed Documents, etc. Neither the listing nor
   description of any item, matter or document in any Schedule hereto nor the
   furnishing or availability for review of any document will be construed to
   modify, qualify or disclose an exception to any representation or warranty of
   any party made herein or in connection herewith, except to the extent that
   such representation or warranty specifically refers to such Schedule and such
   modification, qualification or exception is clearly described in such
   Schedule. The disclosure in one Section of the Schedules shall be deemed to
   be the disclosure with respect to all Sections of the representations and
   warranties to which it is reasonably apparent that such disclosure is
   applicable.


                                      -57-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

      12.8. Counterparts.  This Agreement may be executed in any number of
   counterparts, each of which will be deemed an original, but all of
   which together will constitute but one and the same instrument.  This
   Agreement will become effective when duly executed by each party hereto.

      12.9. Severability. Any term or provision of this Agreement that is
   invalid or unenforceable in any situation in any jurisdiction will not affect
   the validity or enforceability of the remaining terms and provisions hereof
   or the validity or enforceability of the offending term or provision in any
   other situation or in any other jurisdiction. In the event that any provision
   hereof would, under applicable law, be invalid or unenforceable in any
   respect, each party hereto intends that such provision will be construed by
   modifying or limiting it so as to be valid and enforceable to the maximum
   extent compatible with, and possible under, applicable law.

      12.10. Headings. The headings contained in this Agreement are for
   convenience purposes only and will not in any way affect the meaning or
   interpretation hereof.

      12.11. Governing Law. This Agreement, the rights of the parties and all
   Actions arising in whole or in part under or in connection herewith, will be
   governed by and construed in accordance with the domestic substantive laws of
   The Commonwealth of Massachusetts, (with the exception of the transfer of
   title to the Common Shares and the Series A Shares to ViaCell which shall be
   governed by German law), without giving effect to any choice or conflict of
   law provision or rule that would cause the application of the laws of any
   other jurisdiction.

      12.12. Dispute Resolution; Forum.

         12.12.1. Dispute Resolution. Any dispute arising out of or in
      connection with this Agreement, including any question regarding its
      existence, validity or termination (a "Dispute"), shall be referred to and
      finally resolved by binding arbitration under the Rules of the
      International Chamber of Commerce, which Rules are deemed to be
      incorporated by reference into this clause. The parties also agree that
      the arbitration shall be conducted in according to the 1999 International
      Bar Association Rules on the Taking of Evidence in International
      Commercial Arbitration. The arbitration panel shall consist of three
      members. Each party shall nominate one member of the panel. The two
      members shall agree on the third arbitrator within thirty (30) days. If
      the two arbitrators are unable to agree on the third, the International
      Chamber of Commerce shall appoint the third arbitrator. The language to be
      used in the arbitral proceeding shall be English. Each party shall bear
      its own costs associated with the resolution or arbitration of any
      Dispute, and all fees and other costs of the arbitration proceeding shall
      be shared equally between the parties.

         12.12.2. Forum. Each party hereby agrees that any arbitral proceeding
      commenced pursuant to Section 12.12.1 shall be conducted in Boston,
      Massachusetts, if such proceeding is commenced by the Sellers and/or the
      Company and Dusseldorf, Germany if such proceeding is commenced by
      ViaCell.


                                      -58-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

      12.13. Specific Performance. Each of the parties acknowledges and agrees
   that the other parties would be damaged irreparably in the event any of the
   provisions of this Agreement are not performed in accordance with their
   specific terms or otherwise are breached or violated. Accordingly, each of
   the parties agrees that, without posting bond or other undertaking, the other
   parties will be entitled to an injunction or injunctions to prevent breaches
   or violations of the provisions of this Agreement and to enforce specifically
   this Agreement and the terms and provisions hereof in any Action instituted
   in any court of the United States or any state thereof having jurisdiction
   over the parties and the matter in addition to any other remedy to which it
   may be entitled, at law or in equity. Each party further agrees that, in the
   event of any action for specific performance in respect of such breach or
   violation, it will not assert that the defense that a remedy at law would be
   adequate.


                                      -59-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

    IN WITNESS WHEREOF, each of the undersigned has executed this Agreement as
an agreement under seal as of the date first above written.

 THE BUYER:                         VIACELL, INC.


                                    By: /s/ Marc Beer
                                        ------------------------------------
                                        Name: Marc Beer
                                        Title: CEO

 THE COMPANY:                       KOURION THERAPEUTICS AG


                                    By: /s/ Stephan Wnendt
                                        ------------------------------------
                                        Name: Dr. Stephan Wnendt
                                        Title: Seller's Representative:



                 [SELLER SIGNATURES TO FOLLOW ON NEXT PAGE]
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003

 THE SELLERS:                       MPM BIOVENTURES II, L.P.

                                    By:  MPM Asset Management II, L.P.,
                                         its General Partner
                                    By:  MPM Asset Management II LLC,
                                         its General Partner


                                    By:    /s/ Ansbert Gadicke
                                        ------------------------------------
                                          Name:  Ansbert Gadicke
                                          Title:    Manager

                                    MPM BIOVENTURES II-QP, L.P.

                                    By:  MPM Asset Management II, L.P.,
                                         its General Partner
                                    By:  MPM Asset Management II LLC,
                                         its General Partner


                                    By:    /s/ Ansbert Gadicke
                                        ------------------------------------
                                           Name:  Ansbert Gadicke
                                           Title:    Manager

                                    MPM BIOVENTURES GMBH & CO.
                                      PARALLEL-BETEILIGUNGS KG

                                    By:  MPM Asset Management II, L.P., in
                                         its capacity as the Special
                                         Limited Partner
                                    By:  MPM Asset Management II LLC, its
                                         General Partner

                                    By:    /s/ Ansbert Gadicke
                                        ------------------------------------
                                           Name:  Ansbert Gadicke
                                           Title:    Manager

                                    MPM ASSET MANAGEMENT INVESTORS
                                      2001 BVII LLC


                                    By:    /s/ Ansbert Gadicke
                                        ------------------------------------
                                          Name:  Ansbert Gadicke
                                          Title:    Manager


                                      -2-
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003


                                    MPM FOUNDERS LLC


                                    By:    /s/ Ansbert Gadicke
                                        ------------------------------------
                                          Name:  Ansbert Gadicke
                                          Title:    Member
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003


                                    KOURION RM (REGENERATIVE MEDIZIN)
                                      GMBH

                                    By:    /s/ Stephan Wnendt
                                        ------------------------------------
                                       Name:  Dr. Stephan Wnendt
                                       Title:  Seller's Representative

                                    PHILIP COELHO



                                    By:    /s/ Stephan Wnendt
                                        ------------------------------------
                                       Name:  Dr. Stephan Wnendt
                                       Title:  Seller's Representative


                                    DR. JOHANNES FISCHER



                                    By:    /s/ Stephan Wnendt
                                        ------------------------------------
                                       Name:  Dr. Stephan Wnendt
                                       Title:  Seller's Representative


                                    IRK-VERMOGENSVERWALTUNGS GMBH



                                    By:    /s/ Stephan Wnendt
                                        ------------------------------------
                                       Name:  Dr. Stephan Wnendt
                                       Title:  Seller's Representative

                                    TTHU TECHNOLOGIETRANSFER
                                    HEINRICH-HEINE-UNIVERSITAT GMBH



                                    By:    /s/ Stephan Wnendt
                                        ------------------------------------
                                       Name:  Dr. Stephan Wnendt
                                       Title:  Seller's Representative
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003


                                    GESELLSCHAFT VON FREUNDEN UND FORDERERN AN
                                    DER HEINRICH-HEINE-UNIVERSITAT DUSSELDORF
                                    E.V.



                                       By:    /s/ Stephan Wnendt
                                        ------------------------------------
                                       Name:  Dr. Stephan Wnendt
                                       Title:  Seller's Representative

                                    DR. ANDREAS KNIPPER



                                    By:    /s/ Stephan Wnendt
                                        ------------------------------------
                                       Name:  Dr. Stephan Wnendt
                                       Title:  Seller's Representative

                                    DR. HANS-DIETER ROYER



                                    By:    /s/ Stephan Wnendt
                                        ------------------------------------
                                       Name:  Dr. Stephan Wnendt
                                       Title:  Seller's Representative
<PAGE>
                                                        Stock Purchase Agreement
                                                              September 30, 2003



                                                                      SCHEDULE 1

                                SERIES A SELLERS

<TABLE>
<CAPTION>
Series A Seller                             Shares of            Shares of Series I Stock to be Received          Amount of
                                          Series A Stock                                                              Note
                                            to be Sold
                                                            Upfront        Purchase Price      Total Shares
                                                         Consideration      Adjustment       of Series I Stock
<S>                                       <C>            <C>               <C>               <C>                 <C>
MPM BioVentures II-QP, L.P.                    15,437        175,934             45,054            130,880       $ 9,438,694
111 Huntington Ave. - 31st floor
Boston, MA 02199
USA

MPM BioVentures GmbH & Co.                      5,436         61,955             15,866             46,089         3,323,820
Parallel Bet. KG
Prannerstr. 15
80333 Munchen, Germany

MPM BioVentures II, L.P.                        1,703         19,416              4,972             14,444         1,041,675
111 Huntington Ave. - 31st floor
Boston, MA 02199
USA

MPM Asset Management Investors                    321          3,650                935              2,715           195,811
2001 BVII LLC
111 Huntington Ave. - 31st floor
Boston, MA 02199
USA

    TOTALS                                     22,897        260,955             66,827            194,128       $14,000,000
</TABLE>

Aggregate Purchase Price Adjustment:  $1,355,278
Portion of Adjustment Reflected on this Schedule:  $534,616
<PAGE>
                                                                      SCHEDULE 2

                                 COMMON SELLERS

<TABLE>
<CAPTION>
Common Seller                        Shares of             Shares of Series I Stock to be Received
                                     Company
                                     Common
                                   Stock to be
                                      Sold
                                                    For            Upfront         Purchase       Total
                                                 Government     Consideration        Price      Shares of
                                                   Grants                         Adjustment     Series I
                                                                                                  Stock
<S>                                <C>           <C>            <C>               <C>          <C>
Kourion RM (Regenerative             20,400        102,502            188,977        48,394      243,085
Medizin) GmbH
vertreten durch den Geschaftsfuhrer Helmut
Hermanns, geb. 11.04.1942
Helenenstr. 19
40764 Langenfeld, Germany

MPM Founders LLC                      3,453         17,350             31,987         8,191       41,146
vertreten durch den
Gesellschafter
Dr. Ansbert Gadicke, geb.
09.02.1958
111 Huntington Ave. - 31st floor
Boston, MA 02199; USA

Philip H. Coelho, geb                 2,450         12,310             22,696         5,812       29,194
17.11.1943
3146 Gold Camp Drive
Rancho Cordova, CA 95670-6022

Dr. Johannes Fischer, geb.            1,650          8,291             15,285         3,914       19,662
03.07.1964
Schopenhauerstr. 3
41470 Neuss, Germany

IRK - Vermogensverwaltungs GmbH         800          4,020              7,411         1,898        9,533
vertreten durch die
Geschaftsfuhrerin
Dr. Irene Goerttler-Krauspe, geb.
</TABLE>
<PAGE>
                                                                SCHEDULE 2 CONT.

                                 COMMON SELLERS

<TABLE>
<CAPTION>
Common Seller                        Shares of             Shares of Series I Stock to be Received
                                     Company
                                     Common
                                   Stock to be
                                      Sold
                                                    For            Upfront         Purchase       Total
                                                 Government     Consideration        Price      Shares of
                                                   Grants                         Adjustment     Series I
                                                                                                  Stock
<S>                                <C>           <C>            <C>               <C>          <C>
27.10.1955
Am Rindergraben 2
41470 Neuss, Germany

TTHU Technologietransfer                300          1,507              2,779           712        3,574
Heinrich-Heine-Universitat GmbH
vertreten durch die
Geschaftsfuhrer
Roland Oettker, geb.
07.04.1949
Konigsallee 20
40212 Dusseldorf, Germany

Gesellschaft von Freunden und           300          1,507              2,779           712        3,574
Forderern an der
Heinrich-Heine-Universitat
Dusseldorf e.V.
vertreten durch die
Vorstandsmitglieder
Bernd Hebbering, geb.
02.01.1939
Dr. Joachim Funk, geb.
31.05.1942
Wolf-Peter Wirsing, geb.
03.07.1945
Ernst-Schneider-Platz 1
40212 Dusseldorf, Germany

Dr. Andreas Knipper, geb.               250          1,256              2,316           593        2,979
28.02.1962
Am Kaulacker 13
41470 Neuss, Germany

Dr. Hans-Dieter Royer, geb.             250          1,256              2,316           593        2,979
19.03.1948
Am Botanischen Garten 31,
</TABLE>


                                      -2-
<PAGE>
                                                                SCHEDULE 2 CONT.

                                 COMMON SELLERS

<TABLE>
<CAPTION>
Common Seller                        Shares of             Shares of Series I Stock to be Received
                                     Company
                                     Common
                                   Stock to be
                                      Sold
                                                    For            Upfront         Purchase       Total
                                                 Government     Consideration        Price      Shares of
                                                   Grants                         Adjustment     Series I
                                                                                                  Stock
<S>                                <C>           <C>            <C>               <C>          <C>
40225 Dusseldorf, Germany

    TOTALS                           29,853        149,999            276,546        70,819      355,726
</TABLE>

Aggregate Purchase Price Adjustment:  $1,355,278
Portion of Adjustment Reflected on this Schedule:  $566,552


                                      -3-
<PAGE>
                                                                      SCHEDULE 3

                                 ESCROWED SHARES

<TABLE>
<CAPTION>
Seller                                      Initial Number of      Purchase Price        Total Number of
                                             Escrowed Shares         Adjustment       Escrowed Shares to be
                                                                                             Received
<S>                                         <C>                    <C>                <C>
Kourion RM (Regenerative Medizin)                  197,766                11,168                186,598
GmbH
vertreten durch den Geschaftsfuhrer
Helmut Hermanns, geb. 11.04.1942
Helenenstr. 19
40764 Langenfeld, Germany

Philip H. Coelho, geb 17.11.1943                    23,751                 1,341                 22,410
3146 Gold Camp Drive
Rancho Cordova, CA 95670-6022

Dr. Johannes Fischer, geb.                          15,996                   903                 15,093
03.07.1964
Schopenhauerstr. 3
41470 Neuss, Germany

IRK - Vermogensverwaltungs GmbH                      7,756                   438                  7,318
vertreten durch die
Geschaftsfuhrerin
Dr. Irene Goerttler-Krauspe, geb.
27.10.1955
Am Rindergraben 2
41470 Neuss, Germany

TTHU Technologietransfer                             2,908                   164                  2,744
Heinrich-Heine-Universitat GmbH
vertreten durch die Geschaftsfuhrer
Roland Oettker, geb. 07.04.1949
Konigsallee 20
40212 Dusseldorf, Germany
</TABLE>
<PAGE>
                                                              SCHEDULE 3 (CONT.)

<TABLE>
<CAPTION>
Seller                                      Initial Number of      Purchase Price        Total Number of
                                             Escrowed Shares         Adjustment       Escrowed Shares to be
                                                                                             Received
<S>                                         <C>                    <C>                <C>
Gesellschaft von Freunden und                        2,908                   164                  2,744
Forderern an der
Heinrich-Heine-Universitat
Dusseldorf e.V.
vertreten durch die
Vorstandsmitglieder
Bernd Hebbering, geb. 02.01.1939
Dr. Joachim Funk, geb. 31.05.1942
Wolf-Peter Wirsing, geb. 03.07.1945
Ernst-Schneider-Platz 1
40212 Dusseldorf, Germany

Dr. Andreas Knipper, geb. 28.02.1962                 2,424                   137                  2,287
Am Kaulacker 13
41470 Neuss, Germany

Dr. Hans-Dieter Royer, geb.                          2,424                   137                  2,287
19.03.1948
Am Botanischen Garten 31,
40225 Dusseldorf, Germany

    TOTALS                                         255,933                14,452                241,481
</TABLE>

Aggregate Purchase Price Adjustment:  $1,355,278
Portion of Adjustment Reflected on this Schedule:  $115,616
<PAGE>
                                                                      SCHEDULE 4

                                 COMPANY OPTIONS

<TABLE>
<CAPTION>
                                          Person Designated by
           Option Holder              Management to Receive Options        Number of Option Shares
<S>                                 <C>                                    <C>
Prof. Dr. Peter Wernet                                                             350
Dr. Ansbert Gadicke                                                                350
Dr. Stefan Rohrborn                                                                350
Prof. Dr. Detlev Riesner                                                           350
PD Dr. Stephan Wnendt                                                            3,444
Jurgen Peter                                                                     1,035
Dr. Christian van den Bos                                                          527
                                    Dr. Andreas Knipper                            100
                                    Dr. Dimitry Spitkovsky                         100
                                    Dr. Thomas Menne                               100
                                    Dr. Jorg Bender                                100
                                    Dagmar Shittu                                   13
                                    Ines Andermann                                  13
                                    Mathias Altgen                                  13
                                    Marius Willim                                   13
                                    Oezer Degisterici                               13
                                    Barbara Holz                                    13
                                    Janet Mors                                      13
                                    Heike Denck                                     13
                                    Dr. Andreas Fretz                               13
                                    Gisela Muller                                   13
                                    Sabine Mayer                                    13
                                    Stephan Schroot                                 13
                                    Tatjana Jansen                                  13
TOTAL                                                                            6,975
</TABLE>
<PAGE>
                                                                      SCHEDULE 5

                                CONTINGENT SHARES

<TABLE>
<CAPTION>
Seller                                        Initial Number of      Purchase Price        Total Number of
                                              Contingent Shares        Adjustment         Contingent Shares
<S>                                           <C>                    <C>                  <C>
MPM BioVentures II-QP, L.P.                        184,117                10,397                173,720
111 Huntington Ave. - 31st floor
Boston, MA 02199, USA

MPM BioVentures GmbH & Co. Parallel                 64,836                 3,661                 61,175
Bet. KG
Prannerstr. 15
80333 Munchen, Germany

MPM BioVentures II, L.P.                            20,320                 1,147                 19,173
111 Huntington Ave. - 31st floor
Boston, MA 02199, USA

MPM Asset Management Investors 2001                  3,819                   216                  3,603
BVII LLC

111 Huntington Ave. - 31st floor
Boston, MA 02199, USA

MPM Founders LLC                                    33,475                 1,890                 31,585
111 Huntington Ave. - 31st floor
Boston, MA 02199, USA

    TOTALS                                         306,567                17,311                289,256
</TABLE>

Aggregate Purchase Price Adjustment:  $1,355,278
Portion of Adjustment Reflected on this Schedule:  $138,488
<PAGE>
                                                                      SCHEDULE 6

                              PERCENTAGE OWNERSHIP

                     MILESTONE PAYMENT PERCENTAGE OWNERSHIP

<TABLE>
<CAPTION>
                     SHAREHOLDER:                      PERCENTAGE OWNERSHIP:
<S>                                                    <C>
Kourion RM (Regenerative Medizin) GmbH                         35.158472%
MPM BioVentures II-QP L.P.                                     32.731848%
MPM BioVentures GmbH & Co. Parallel Bet.KG                     11.526464%
MPM Founders LLC                                                5.951088%
Philip H. Coelho                                                4.222464%
MPM BioVentures II L.P.                                         3.612361%
Dr. Johannes Fischer                                            2.843700%
IRK-Vermogensverwaltungs GmbH                                   1.378764%
MPM Asset Management Investors 2001 BVII LLC                    0.679041%
THHU Technologietransfer Heinrich-Heine-Universitat             0.517036%
GmbH
Gesellschaft von Freunden und Forderern an der                  0.517036%
Heinrich-Heine-Universitat Dusseldorf e.V.
Dr. Andreas Knipper                                             0.430864%
Dr. Hans-Dieter Royer                                           0.430864%

                                                              100.000000%
</TABLE>