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                                                                   EXHIBIT 10.27


                           THIRD AMENDED AND RESTATED
                          REGISTRATION RIGHTS AGREEMENT

                                                               October 25, 2001


To each of the several Purchasers named in Exhibit A attached hereto.

Ladies and Gentlemen:

         Pursuant to the Registration Rights Agreement dated as of November 26,
1997 by and among t. Breeders, Inc., now known as Viacell, Inc., a Delaware
corporation (the "Company"), and the purchasers listed in the signature pages
thereto (as amended and restated by that certain Amended and Restated
Registration Rights Agreement, dated April 11, 2000, and as further amended by
the Second Amended and Restated Registration Rights Agreement, dated November
10, 2000, the "Old Registration Rights Agreement"), the Company granted certain
registration rights to the holders of the Company's (i) Series A Convertible
Preferred Stock, $.01 par value (the "Series A Preferred"), (ii) Series B
Convertible Preferred Stock, $.01 par value (the "Series B Preferred"), (iii)
Series C Convertible Preferred Stock, $.01 par value (the "Series C Preferred")
(iv) Series D Convertible Preferred Stock, $.01 par value (the "Series D
Preferred"), (v) Series E Convertible Preferred Stock, $.01 par value (the
"Series E Preferred"), (vi) Series F Convertible Preferred Stock, $.01 par value
(the "Series F Preferred"), (vii) Series G Convertible Preferred Stock, $.01 par
value (the "Series G Preferred"); (viii) Series H Convertible Preferred Stock,
$.01 par value (the "Series H Preferred") and (ix) the Warrant Agreements
exercisable for Common Stock (as defined herein) issuable pursuant to the Series
D Unit/Series E Preferred Stock Purchase Agreement, dated as of November 26,
1997 (the "Warrants"). Pursuant to this Third Amended and Restated Registration
Rights Agreement (this "Agreement"), the Company is granting certain
registration rights to the holders of shares of Series I Preferred Stock, $.01
par value (the "Series I Preferred," and together with the Series A Preferred,
Series B Preferred, Series C Preferred, Series D Preferred, Series E Preferred,
Series F Preferred, Series G Preferred and the Series H Preferred (the
"Preferred Securities"), who purchase such shares pursuant to a Series I
Convertible Preferred Stock Purchase Agreement of even date herewith. In
addition, the parties to the Old Registration Rights Agreement intend that, upon
execution of this Agreement, the provisions of the Old Registration Rights
Agreement shall be terminated and superseded in their entirety by this
Agreement. The Company covenants and agrees with each of you as follows:

         1. Termination of Old Registration Rights Provisions. The Old
Registration Rights Agreement is hereby terminated in its entirety and is of no
further force or effect.

         2. Certain Definitions. As used in this Agreement, the following terms
shall have the following respective meanings:

             (a) "Commission" shall mean the Securities and Exchange Commission,
or any other federal agency at the time administering the Securities Act.

             (b) "Common Stock" shall mean the Common Stock, $.01 par value, of
the Company, as constituted as of the date of this Agreement.


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             (c) "Conversion Shares" shall mean shares of Common Stock issued
upon conversion or exercise of the Preferred Securities.

             (d) "Exchange Act" shall mean the Securities Exchange Act of 1934,
as amended, or any similar federal statute, and the rules and regulations of the
Commission thereunder, all as the same shall be in effect at the time.

             (e) "Registration Expenses" shall mean the expenses so described in
Section 8.

             (f) "Restricted Stock" shall mean the Conversion Shares, excluding
Conversion Shares which have been (a) registered under the Securities Act
pursuant to an effective registration statement filed thereunder and disposed of
in accordance with the registration statement covering them or (b) publicly sold
pursuant to Rule 144 under the Securities Act.

             (g) "Securities Act" shall mean the Securities Act of 1933, as
amended, or any similar federal statute, and the rules and regulations of the
Commission thereunder, all as the same shall be in effect at the time.

             (h) "Selling Expenses" shall mean the expenses so described in
Section 8.

             (i) "Senior Securities" shall mean the (i) Series C Preferred,
Series D Preferred, Series E Preferred, Series F Preferred, Series G Preferred,
Series H Preferred and Series I Preferred and (ii) the Warrants.

         3. Certain Transfers

             (a) Notice of Proposed Transfer. Prior to any proposed transfer of
any Preferred Securities or Conversion Shares (other than under the
circumstances described in Sections 4, 5 or 6), the holder thereof shall give
written notice to the Company of its intention to effect such transfer. Each
such notice shall describe the manner of the proposed transfer and, if requested
by the Company, shall be accompanied by an opinion of counsel satisfactory to
the Company (it being agreed that Palmer & Dodge LLP or Goodwin Procter & Hoar
LLP shall be satisfactory) to the effect that the proposed transfer may be
effected without registration under the Securities Act, whereupon the holder of
such stock shall be entitled to transfer such stock in accordance with the terms
of its notice; provided, however, that no such opinion of counsel shall be
required for a transfer to (i) any affiliate of such holder as defined under
Rule 144 of the Securities Act, (ii) its partners, shareholders, members or
other equity holders, (iii) any Immediate Family member (as defined below), (iv)
any heir, executor or legal representative, (v) to any charitable organization
qualified under Section 501(c)(3) of the Internal Revenue Code of 1986, as
amended, for no consideration, or (vi) any trustee of an inter-vivos trust or
testamentary trust for the benefit of Immediate Family members. Each certificate
for Preferred Securities or Conversion Shares transferred as above provided
shall bear the legend set forth in Section 3(b), except that such certificate
shall not bear such legend if (i) such transfer is in accordance with the
provisions of Rule 144 or Rule 144A (or any other rule permitting public sale
without registration under the Securities Act) or (ii) the opinion of counsel
referred to above is to the further effect that the transferee and any
subsequent transferee (other than an affiliate of the Company) would be entitled
to transfer such securities in a public sale without registration under the
Securities Act. The restrictions provided for in this Section 3(a) shall not
apply to securities which are not required to bear


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the legend prescribed by Section 3(b) in accordance with the provisions of that
Section. As used herein, "Immediate Family" shall mean any lineal ancestors or
descendants, spouse, sibling, in-laws, aunts, uncles, nieces and nephews.

             (b) Restrictive Legend. Each certificate representing Preferred
Securities or Conversion Shares shall, except as otherwise provided in Section
3(a) or this Section 3(b), be stamped or otherwise imprinted with a legend
substantially in the following form:

             "THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES
             ACT OF 1933 AND MAY NOT BE TRANSFERRED OR OTHERWISE DISPOSED
             OF UNLESS IT HAS BEEN REGISTERED UNDER THAT ACT OR AN
             EXEMPTION FROM REGISTRATION IS AVAILABLE."

A certificate shall not bear such legend if in the opinion of counsel
satisfactory to the Company (it being agreed that Palmer & Dodge LLP shall be
satisfactory) the securities represented thereby may be publicly sold without
registration under the Securities Act.

         4. Required Registration.

             (a) At any time after the earlier of (i) 180 days after any
registration statement covering the initial public offering of securities of the
Company under the Securities Act shall have become effective, and (ii) November
15, 2003, the holders of Senior Securities constituting at least 50% of the
total outstanding shares of Restricted Stock then held by the holders of Senior
Securities may request the Company to register under the Securities Act all or
any portion of the shares of Restricted Stock held by such requesting holder or
holders for sale in the manner specified in such notice. For purposes of this
Section 4 and Sections 5, 6, 13(a) and 13(d), the term "Restricted Stock" shall
be deemed to include the number of shares of Restricted Stock which would be
issuable to a holder of Preferred Securities upon conversion or exercise of
shares of Preferred Securities held by such holder at such time, provided,
however, that the only securities which the Company shall be required to
register pursuant hereto shall be shares of Common Stock, and provided, further,
however, that, in any underwritten public offering contemplated by this Section
4 or Sections 5 and 6, the holders of Preferred Securities shall be entitled to
sell such Preferred Securities to the underwriters for conversion or exercise
and sale of the shares of Common Stock issued upon conversion or exercise
thereof. Notwithstanding anything to the contrary contained herein, no request
may be made under this Section 4 within 180 days after the effective date of a
registration statement filed by the Company covering a firm commitment
underwritten public offering in which the holders of Restricted Stock shall have
been entitled to join pursuant to Sections 5 or 6 and in which there shall have
been effectively registered all shares of Restricted Stock as to which
registration shall have been requested. If any registration made pursuant to
this Section 4 is an underwritten offering, then the holders of the Senior
Securities holding at least 50% of the total shares of Restricted Stock being
included in the underwritten offering shall select the underwriter, subject to
the consent of the Company (which consent shall not be unreasonably withheld).

             (b) Following receipt of any notice under this Section 4, the
Company shall immediately notify all holders of Restricted Stock from whom
notice has not been received and shall use its best efforts to register within
60 days of the initial request under the Securities Act, for public sale in
accordance with the method of disposition specified in such notice from
requesting holders, the number of shares of Restricted Stock specified in such
notice (and in all notices received by the Company from other holders within 30
days after

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the giving of such notice by the Company). If such method of disposition shall
be an underwritten public offering, the holders of a majority of the shares of
Restricted Stock to be sold in such offering may designate the managing
underwriter of such offering, subject to the approval of the Company, which
approval shall not be unreasonably withheld or delayed. The Company shall be
obligated to register Restricted Stock pursuant to this Section 4 on two (2)
occasions only, provided, however, that such obligation shall be deemed
satisfied only when a registration statement covering all shares of Restricted
Stock specified in notices received as aforesaid for sale in accordance with the
method of disposition specified by the requesting holders shall have become
effective and, if such method of disposition is a firm commitment underwritten
public offering, all such shares shall have been sold pursuant thereto.

             (c) The Company shall be entitled to include in the registration
statement referred to in this Section 4, for sale in accordance with the method
of disposition specified by the requesting holders, shares of Common Stock to be
sold by the Company for its own account, except as and to the extent that, in
the opinion of the managing underwriter (if such method of disposition shall be
an underwritten public offering), such inclusion would adversely affect the
marketing of the Restricted Stock to be sold. Except for registration statements
on Form S-4, S-8 or any successor thereto, the Company will not file with the
Commission any other registration statement with respect to its Common Stock,
whether for its own account or that of other stockholders, from the date of
receipt of a notice from requesting holders pursuant to this Section 4 until the
completion of the period of distribution of the registration contemplated
thereby.

         5. Incidental Registration. If the Company at any time (other than
pursuant to Section 4 or Section 6) proposes to register any of its securities
under the Securities Act for sale to the public, whether for its own account or
for the account of other security holders or both (except with respect to
registration statements on Forms S-4, S-8 or another form not available for
registering the Restricted Stock for sale to the public), each such time it will
give written notice to all holders of outstanding Restricted Stock of its
intention so to do. Upon the written request of any such holder, received by the
Company within 30 days after the giving of any such notice by the Company, to
register any of its Restricted Stock (which request shall state the intended
method of disposition thereof), the Company will use its best efforts to cause
the Restricted Stock as to which registration shall have been so requested to be
included in the securities to be covered by the registration statement proposed
to be filed by the Company, all to the extent requisite to permit the sale or
other disposition by the holder (in accordance with its written request) of such
Restricted Stock so registered. In the event that any registration pursuant to
this Section 5 shall be, in whole or in part, an underwritten public offering of
Common Stock, the number of shares of Restricted Stock to be included in such an
underwriting may be reduced (first by excluding Series A Preferred and Series B
Preferred holders on a pro rata basis and second, if necessary by excluding the
holders of the Senior Securities on a pro rata basis) if and to the extent that
the managing underwriter shall be of the opinion that such inclusion would
adversely affect the marketing of the securities to be sold by the Company
therein, provided, however, that such number of shares of Restricted Stock shall
not be reduced if any shares are to be included in such underwriting for the
account of any person other than the Company or requesting holders of Restricted
Stock, and provided, further, however, that in no event may less than one-third
of the total number of shares of Common Stock to be included in such
underwriting be made available for shares of Restricted Stock. Notwithstanding
the foregoing provisions, the Company may withdraw any registration statement
referred to in this Section 5 without thereby incurring any liability to the
holders of Restricted Stock.


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         6. Registration on Form S-3. In addition to the rights set forth in
Section 4, if at any time (i) a holder or holders of Preferred Securities or
Restricted Stock request that the Company file a registration statement on Form
S-3 or any successor thereto for a public offering of all or any portion of the
shares of Restricted Stock held by such requesting holder or holders, the
reasonably anticipated aggregate price to the public of which would exceed
$1,000,000, which registration statement may be a shelf registration statement,
and (ii) the Company is a registrant entitled to use Form S-3 or any successor
thereto to register such shares, then the Company shall use its best efforts to
register within 30 days of such request under the Securities Act on Form S-3 or
any successor thereto, for public sale in accordance with the method of
disposition specified in such notice, the number of shares of Restricted Stock
specified in such notice. Whenever the Company is required by this Section 6 to
use its best efforts to effect the registration of Restricted Stock, each of the
procedures and requirements of Section 4 (including but not limited to the
requirement that the Company notify all holders of Restricted Stock from whom
notice has not been received and provide them with the opportunity to
participate in the offering) shall apply to such registration, provided,
however, that there shall be no limitation on the number of registrations on
Form S-3 which may be requested and obtained under this Section 6, and provided,
further, however, that the requirements contained in the first sentence of
Section 4(a) shall not apply to any registration on Form S-3 which may be
requested and obtained under this Section 6.

         7. Registration Procedures. If and whenever the Company is required by
the provisions of Sections 4, 5 or 6 to use its best efforts to effect the
registration of any shares of Restricted Stock under the Securities Act, the
Company will, as expeditiously as possible:

             (a) prepare and file with the Commission a registration statement
(which, in the case of an underwritten public offering pursuant to Section 4,
shall be on Form S-1 or other form of general applicability satisfactory to the
managing underwriter selected as herein provided) with respect to such
securities and use its best efforts to cause such registration statement to
become and remain effective for the period of the distribution contemplated
thereby (determined as hereinafter provided). Notwithstanding the provisions of
Section 7(a), the Company's obligation to file a registration statement, or
cause such registration statement to become and remain effective, shall be
suspended for a period not to exceed 90 days in any 12-month period if there
exists at the time material non-public information relating to the Company
which, in the reasonable opinion of the Company, should not be disclosed and the
Company has provided the holders of Preferred Securities and Restricted Stock
with prior notice in writing of such suspension;

             (b) prepare and file with the Commission such amendments and
supplements to such registration statement and the prospectus used in connection
therewith as may be necessary to keep such registration statement effective for
the period specified in paragraph (a) above and comply with the provisions of
the Securities Act with respect to the disposition of all Restricted Stock
covered by such registration statement in accordance with the sellers' intended
method of disposition set forth in such registration statement for such period;

             (c) furnish to each seller of Restricted Stock and to each
underwriter such number of copies of the registration statement and the
prospectus included therein (including each preliminary prospectus) as such
persons reasonably may request in order to facilitate the public sale or other
disposition of the Restricted Stock covered by such registration statement;


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             (d) use its best efforts to register or qualify the Restricted
Stock covered by such registration statement under the securities or "blue sky"
laws of such jurisdictions as the sellers of Restricted Stock or, in the case of
an underwritten public offering, the managing underwriter reasonably shall
request, provided, however, that the Company shall not for any such purpose be
required to qualify generally to transact business as a foreign corporation in
any jurisdiction where it is not so qualified or to consent to general service
of process in any such jurisdiction;

             (e) use its best efforts to list the Restricted Stock covered by
such registration statement with any securities exchange on which the Common
Stock of the Company is then listed;

             (f) immediately notify each seller of Restricted Stock and each
underwriter under such registration statement, at any time when a prospectus
relating thereto is required to be delivered under the Securities Act, of the
happening of any event of which the Company has knowledge as a result of which
the prospectus contained in such registration statement, as then in effect,
includes an untrue statement of a material fact or omits to state a material
fact required to be stated therein or necessary to make the statements therein
not misleading in light of the circumstances then existing;

             (g) if the offering is underwritten and at the request of any
seller of Restricted Stock, use its best efforts to furnish on the date that
Restricted Stock is delivered to the underwriters for sale pursuant to such
registration: (i) an opinion dated such date of counsel representing the Company
for the purposes of such registration, addressed to the underwriters and to such
seller, stating that such registration statement has become effective under the
Securities Act and that (A) to the best knowledge of such counsel, no stop order
suspending the effectiveness thereof has been issued and no proceedings for that
purpose have been instituted or are pending or contemplated under the Securities
Act, (B) the registration statement, the related prospectus and each amendment
or supplement thereof comply as to form in all material respects with the
requirements of the Securities Act (except that such counsel need not express
any opinion as to financial statements contained therein) and (C) to such other
effects as reasonably may be requested by counsel for the underwriters or by
such seller or its counsel and (ii) a letter dated such date from the
independent public accountants retained by the Company, addressed to the
underwriters and to such seller, stating that they are independent public
accountants within the meaning of the Securities Act and that, in the opinion of
such accountants, the financial statements of the Company included in the
registration statement or the prospectus, or any amendment or supplement
thereof, comply as to form in all material respects with the applicable
accounting requirements of the Securities Act, and such letter shall
additionally cover such other financial matters (including information as to the
period ending no more than five business days prior to the date of such letter)
with respect to such registration as such underwriters reasonably may request;
and

             (h) make available for inspection by each seller of Restricted
Stock, any underwriter participating in any distribution pursuant to such
registration statement, and any attorney, accountant or other agent retained by
such seller or underwriter, all financial and other records, pertinent corporate
documents and properties of the Company, and cause the Company's officers,
directors and employees to supply all information reasonably requested by any
such seller, underwriter, attorney, accountant or agent in connection with such
registration statement.


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         For purposes of Section 7(a) and 7(b) and of Section 4(c), the period
of distribution of Restricted Stock in a firm commitment underwritten public
offering shall be deemed to extend until each underwriter has completed the
distribution of all securities purchased by it, and the period of distribution
of Restricted Stock in any other registration shall be deemed to extend until
the earlier of the sale of all Restricted Stock covered thereby and 180 days
after the effective date thereof.

         In connection with each registration hereunder, the sellers of
Restricted Stock will furnish to the Company in writing such information with
respect to themselves and the proposed distribution by them as reasonably shall
be necessary in order to assure compliance with federal and applicable state
securities laws.

         In connection with each registration pursuant to Sections 4, 5 or 6
covering an underwritten public offering, the Company and each seller agree to
enter into a written agreement with the managing underwriter selected in the
manner herein provided in such form and containing such provisions as are
customary in the securities business for such an arrangement between such
underwriter and companies of the Company's size and investment stature.

         8. Expenses. All expenses incurred by the Company in complying with
Sections 4, 5 and 6, including, without limitation, all registration and filing
fees, printing expenses, fees and disbursements of counsel and independent
public accountants for the Company, fees and expenses (including counsel fees)
incurred in connection with complying with state securities or "blue sky" laws,
fees of the National Association of Securities Dealers, Inc., transfer taxes,
fees of transfer agents and registrars, costs of insurance and fees and
disbursements of one counsel for the sellers of Restricted Stock, but excluding
any Selling Expenses, are called "Registration Expenses". All underwriting
discounts and selling commissions applicable to the sale of Restricted Stock are
called "Selling Expenses".

         The Company will pay all Registration Expenses in connection with each
registration statement under Sections 4, 5 or 6. All Selling Expenses in
connection with each registration statement under Sections 4, 5 or 6 shall be
borne by the participating sellers in proportion to the number of shares sold by
each, or by such participating sellers other than the Company (except to the
extent the Company shall be a seller) as they may agree.

         9. Indemnification and Contribution.

             (a) By the Company. In the event of a registration of any of the
Restricted Stock under the Securities Act pursuant to Sections 4, 5 or 6, the
Company will indemnify and hold harmless each seller of such Restricted Stock
thereunder, each underwriter of such Restricted Stock thereunder and each other
person, if any, who controls such seller or underwriter within the meaning of
the Securities Act, against any losses, claims, damages or liabilities, joint or
several, to which such seller, underwriter or controlling person may become
subject under the Securities Act or otherwise, insofar as such losses, claims,
damages or liabilities (or actions in respect thereof) arise out of or are based
upon any untrue statement or alleged untrue statement of any material fact
contained in any registration statement under which such Restricted Stock was
registered under the Securities Act pursuant to Sections 4, 5 or 6, any
preliminary prospectus or final prospectus contained therein, or any amendment
or supplement thereof, or arise out of or are based upon the omission or alleged
omission to state therein a material fact required to be stated therein or
necessary to make the statements therein not misleading, and will reimburse each
such seller, each such underwriter and each such controlling person for any
legal or other expenses reasonably incurred by them in connection with
investigating or defending any such loss, claim, damage, liability or action,


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provided, however, that the Company will not be liable in any such case if and
to the extent that any such loss, claim, damage or liability arises out of or is
based upon an untrue statement or alleged untrue statement or omission or
alleged omission so made in conformity with information furnished by any such
seller, any such underwriter or any such controlling person in writing
specifically for use in such registration statement or prospectus.

             (b) By each Preferred Holder. In the event of a registration of any
of the Restricted Stock under the Securities Act pursuant to Sections 4, 5 or 6,
each seller of such Restricted Stock thereunder, severally and not jointly, will
indemnify and hold harmless the Company, each person, if any, who controls the
Company within the meaning of the Securities Act, each officer of the Company
who signs the registration statement, each director of the Company, each
underwriter and each person who controls any underwriter within the meaning of
the Securities Act, against all losses, claims, damages or liabilities, joint or
several, to which the Company or such officer, director, underwriter or
controlling person may become subject under the Securities Act or otherwise,
insofar as such losses, claims, damages or liabilities (or actions in respect
thereof) arise out of or are based upon any untrue statement or alleged untrue
statement of any material fact contained in the registration statement under
which such Restricted Stock was registered under the Securities Act pursuant to
Sections 4, 5 or 6, any preliminary prospectus or final prospectus contained
therein, or any amendment or supplement thereof, or arise out of or are based
upon the omission or alleged omission to state, therein a material fact required
to be stated therein or necessary to make the statements therein not misleading,
and will reimburse the Company and each such officer, director, underwriter and
controlling person for any legal or other expenses reasonably incurred by them
in connection with investigating or defending any such loss, claim, damage,
liability or action, provided, however, that such seller will be liable
hereunder in any such case if and only to the extent that any such loss, claim,
damage or liability arises out of or is based upon an untrue statement or
alleged untrue statement or omission or alleged omission made in reliance upon
and in conformity with information pertaining to such seller, as such, furnished
in writing to the Company by such seller specifically for use in such
registration statement or prospectus, and provided, further, however, that the
liability of each seller hereunder shall be limited to the proportion of any
such loss, claim, damage, liability or expense which is equal to the proportion
that the public offering price of the shares sold by such seller under such
registration statement bears to the total public offering price of all
securities sold thereunder, but not in any event to exceed the proceeds received
by such seller from the sale of Restricted Stock covered by such registration
statement.

             (c) Notice. Promptly after receipt by an indemnified party
hereunder of notice of the commencement of any action, such indemnified party
shall, if a claim in respect thereof is to be made against the indemnifying
party hereunder, notify the indemnifying party in writing thereof, but the
omission so to notify the indemnifying party shall not relieve it from any
liability which it may have to such indemnified party other than under this
Section 9 and shall only relieve it from any liability which it may have to such
indemnified party under this Section 9 if and to the extent the indemnifying
party is prejudiced by such omission. In case any such action shall be brought
against any indemnified party and it shall notify the indemnifying party of the
commencement thereof, the indemnifying party shall be entitled to participate in
and, to the extent it shall wish, to assume and undertake the defense thereof
with counsel satisfactory to such indemnified party, and, after notice from the
indemnifying party to such indemnified party of its election so to assume and
undertake the defense thereof, the indemnifying party shall not be liable to
such indemnified party under this Section 9 for any legal expenses subsequently
incurred by such indemnified party in connection with the


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defense thereof other than reasonable costs of investigation and of liaison with
counsel so selected, provided, however, that, if the defendants in any such
action include both the indemnified party and the indemnifying party and the
indemnified party shall have reasonably concluded that there may be reasonable
defenses available to it which are different from or additional to those
available to the indemnifying party or if the interests of the indemnified party
reasonably may be deemed to conflict with the interests of the indemnifying
party, the indemnified party shall have the right to select a separate counsel
and to assume such legal defenses and otherwise to participate in the defense of
such action, with the expenses and fees of such separate counsel and other
expenses related to such participation to be reimbursed by the indemnifying
party as incurred.

             (d) Contribution. In order to provide for just and equitable
contribution to joint liability under the Securities Act in any case in which
either (i) any holder of Restricted Stock exercising rights under this
Agreement, or any controlling person of any such holder, makes a claim for
indemnification pursuant to this Section 9 but it is judicially determined (by
the entry of a final judgment or decree by a court of competent jurisdiction and
the expiration of time to appeal or the denial of the last right of appeal) that
such indemnification may not be enforced in such case notwithstanding the fact
that this Section 9 provides for indemnification in such case, or, (ii)
contribution under the Securities Act may be required on the part of any such
selling holder or any such controlling person in circumstances for which
indemnification is provided under this Section 9; then, and in each such case,
the Company and such holder will contribute to the aggregate losses, claims,
damages or liabilities to which they may be subject (after contribution from
others) (i) in such proportion as is appropriate to reflect the relative fault
of the Company on the one hand and of such holder on the other in connection
with the statements or omissions which resulted in such losses, claims, damages
or liabilities, as well as any other relevant equitable considerations or (ii)
if the allocation provided by clause (i) above is not permitted by applicable
law, in such proportion so that such holder is responsible for the portion
represented by the percentage that the public offering price of its Restricted
Stock offered by the registration statement bears to the public offering price
of all securities offered by such registration statement, and the Company is
responsible for the remaining portion; provided, however, that, in any such
case, (A) no such holder will be required to contribute any amount in excess of
the public offering price of all such Restricted Stock offered by it pursuant to
such registration statement; and (B) no person or entity guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the Securities Act)
will be entitled to contribution from any person or entity who was not guilty of
such fraudulent misrepresentation. The relative fault of the Company on the one
hand and of such holder on the other shall be determined by reference to, among
other things, whether the untrue statement or alleged untrue statement of a
material fact or omission or alleged omission relates to information supplied by
the Company or such holder and the parties' relative intent, knowledge, access
to information and opportunity to correct or prevent such statement or omission.

         10. Changes in Common Stock or Preferred Stock. If, and as often as,
there is any change in the Common Stock or the Preferred Stock by way of a stock
split, stock dividend, combination or reclassification, or through a merger,
consolidation, reorganization or recapitalization, or by any other means,
appropriate adjustment shall be made in the provisions hereof so that the rights
and privileges granted hereby shall continue with respect to the Common Stock or
the Preferred Stock as so changed.


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         11. Rule 144 Reporting. With a view to making available the benefits of
certain rules and regulations of the Commission which may at any time permit the
sale of the Restricted Stock to the public without registration, at all times
after 90 days after any registration statement covering a public offering of
securities of the Company under the Securities Act shall have become effective,
the Company agrees to:

             (a) make and keep public information available, as those terms are
understood and defined in Rule 144 under the Securities Act;

             (b) use its best efforts to file with the Commission in a timely
manner all reports and other documents required of the Company under the
Securities Act and the Exchange Act; and

             (c) furnish to each holder of Restricted Stock forthwith upon
request a written statement by the Company as to its compliance with the
reporting requirements of such Rule 144 and of the Securities Act and the
Exchange Act, a copy of the most recent annual or quarterly report of the
Company, and such other reports and documents so filed by the Company as such
holder may reasonably request in availing itself of any rule or regulation of
the Commission allowing such holder to sell any Restricted Stock without
registration.

         12. Representations and Warranties of the Company. The Company
represents and warrants to you as follows:


             (a) The execution, delivery and performance of this Agreement by
the Company have been duly authorized by all requisite corporate action and will
not violate any provision of law, any order of any court or other agency of
government, the Certificate of Incorporation, as amended to date, or By-laws of
the Company or any provision of any indenture, agreement or other instrument to
which it or any or its properties or assets is bound, conflict with, result in a
breach of or constitute (with due notice or lapse of time or both) a default
under any such indenture, agreement or other instrument or result in the
creation or imposition of any lien, charge or encumbrance of any nature
whatsoever upon any of the properties or assets of the Company.

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

         13. Miscellaneous.

             (a) Successors and Assigns. All covenants and agreements contained
in this Agreement by or on behalf of any of the parties hereto shall bind and
inure to the benefit of the respective successors and assigns of the parties
hereto (including without limitation transferees of any Preferred Securities or
Restricted Stock), whether so expressed or not, provided, however, that
registration rights conferred herein on the holders of Preferred Securities or
Restricted Stock shall only inure to the benefit of a transferee of Preferred
Securities or Restricted Stock if (i) there is transferred to such transferee at
least 20% of the total shares of Restricted Stock originally issued pursuant to
the respective purchase agreement under which such shares of Restricted Stock
were originally purchased, to the direct or indirect transferor of such
transferee or (ii) such transferee is a partner, shareholder or affiliate of a
party hereto; provided further that such transferee agrees in writing to be
bound by all terms and conditions of this Agreement.


                                       10

<PAGE>

             (b) Notices. All notices, requests, consents and other
communications hereunder shall be in writing and shall be deemed effectively
given upon being delivered in person, mailed by the next business day service of
a nationally recognized courier, mailed by certified or registered mail, return
receipt requested, or sent by telecopier (and promptly confirmed by any of the
foregoing methods of delivery), addressed as follows:


                           If to the Company:

                           131 Clarendon Street
                           Boston, Massachusetts 02116
                           Attention:  Marc D. Beer
                           Tel:  (617) 266-4373
                           Fax: (617) 266-9391

                           with a copy to:

                                    (i) if prior to November 5, 2001:

                           Paul M. Kinsella, Esq.
                           Palmer & Dodge LLP
                           One Beacon Street
                           Boston, MA 02108
                           Tel:  (617) 573-0513
                           Fax:  (617) 227-4420

                                    (ii) if on or after November 5, 2001:

                           Paul M. Kinsella, Esq.
                           Palmer & Dodge LLP
                           111 Huntington Avenue
                             at Prudential Center
                           Boston, MA 02199-7613
                           Tel:  (617) 573-0513
                           Fax:  (617) 227-4420



                           If to a Purchaser:

at such Purchaser's respective address set forth on Exhibit A, with a copy (i)
in the case of communications to Nomura International plc, to:

                           Doug Warner
                           Weil, Gotshal & Manges
                           One South Place
                           London EC2M 2WG
                           Tel: 44 20 7903 1036
                           Fax: 44 20 7903 0990

                                       11

<PAGE>

(ii) in the case of communications to BB BioVentures L.P., MPM BioVentures
Parallel Fund, L.P., or MPM Asset Management Investors 2000A LLC, to:

                           Laura C. Hodges Taylor, Esq.
                           Goodwin, Procter & Hoar LLP
                           Exchange Place
                           Boston, MA 02109
                           Tel: (617) 570 1000
                           Fax: (617) 523 1231

(iii) in the case of communications to TD Javelin Capital Fund II, L.P., TD
Lighthouse Capital Fund, L.P., Zero Stage Capital V Limited Partnership, or Zero
Stage Capital VI, L.P., to:

                           Law Offices of Gloria M. Skigen
                           One Greenwich Plaza, Third Floor
                           Greenwich, CT 06830
                           Tel: (203) 861 1717
                           Fax: (203) 861 2498

(iv) in the case of communications to Cynthia A. Fisher, Cynthia A. Fisher 1999
Family Trust, Fisher (WD) Family LP or Aurora Assets LLC, to:

                                    John J. Concannon III
                                    Bingham Dana LLP
                                    150 Federal Street
                                    Boston, Massachusetts 02110
                                    Tel: (617) 951-8874
                                    Fax: (617) 951-8736

and (v) in the case of Genzyme Corporation to :

                                    Genzyme Corporation
                                    One Kendall Square
                                    Cambridge, Massachusetts 07139
                                    Attention: Chief Legal Officer
                                    Tel.: (617)252-7500
                                    Fax: (617-252-7553

or, in any such case, at such other address or addresses as may have been
furnished in writing to the Company by such Purchaser.

         If to any subsequent holder of Preferred Securities or Restricted
Stock:

at such address as may have been furnished to the Company in writing by such
holder; or, in any such case, at such other address or addresses as shall have
been furnished in writing to the Company (in the case of a holder of Preferred
Securities or Restricted Stock) or to the holders of Preferred Securities or
Restricted Stock (in the case of the Company) in accordance with the provisions
of this paragraph.


                                       12

<PAGE>

             (c) Governing Law. This Agreement shall be governed by and
construed in accordance with the laws of the Commonwealth of Massachusetts
without reference to conflicts or choice of law provisions thereof.

             (d) Amendment; Waiver. This Agreement may not be amended or
modified, and no provision hereof may be waived, without the written consent of
the Company and the holders of at least 75% of the outstanding shares of
Restricted Stock, acting together as a single class.

             (e) Counterparts. This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

             (f) Termination of Registration Rights. The obligations of the
Company to register shares of Restricted Stock under Sections 4, 5 or 6 shall
terminate on the eleventh anniversary of the date of this Agreement.

             (g) "Lock-Up" Agreement. If requested in writing by the
underwriters for the initial underwritten public offering of securities of the
Company, each holder of Restricted Stock who is a party to this Agreement shall
agree not to sell publicly any shares of Restricted Stock or any other shares of
Common Stock (other than shares of Restricted Stock or other shares of Common
Stock being registered in such offering), without the consent of such
underwriters, for a period of not more than 180 days following the effective
date of the registration statement relating to such offering; provided, however,
that all persons entitled to registration rights with respect to shares of
Common Stock who are not parties to this Agreement, all other persons selling
shares of Common Stock in such offering, all persons holding in excess of 1% of
the capital stock of the Company on a fully diluted basis and all executive
officers and directors of the Company shall also have agreed not to sell
publicly their Common Stock under the circumstances and pursuant to the terms
set forth in this Section 13(g).

             (h) Subsequent Registration Rights. The Company shall not grant to
any third party any registration rights, except in connection with a new equity
financing, and in such case, such registration rights shall not be more
favorable than any of those contained herein, so long as any of the registration
rights under this Agreement remain in effect.

             (i) Severability. If any provision of this Agreement shall be held
to be illegal, invalid or unenforceable, such illegality, invalidity or
unenforceability shall attach only to such provision and shall not in any manner
affect or render illegal, invalid or unenforceable any other provision of this
Agreement, and this Agreement shall be carried out as if any such illegal,
invalid or unenforceable provision were not contained herein.

             (j) Injunctive Relief. Each of the parties acknowledge that any
breach of this Agreement by any one of them will cause irreparable harm to the
other parties thereto and that in the event of such breach, the parties hereto
shall be entitled, in addition to monetary damages and to any other remedies
available under this Agreement and at law, to equitable relief, including
injunctive relief.

             (k) Entire Agreement. This Agreement together with the Related
Agreements (as defined in the Purchase Agreement) embodies the entire agreement
and understanding between the parties hereto with respect to the subject matter
hereof and


                                       13

<PAGE>

supersedes all prior oral or written agreements and understanding relating to
the subject matter hereof, including, without limitation, the Old Registration
Rights Agreement. No statement, representation, warranty, covenant or agreement
of any kind not expressly set forth in this Agreement shall affect, or be used
to interpret, change or restrict, the express terms and provisions of this
Agreement.

             (l) Captions. The captions of the sections, subsections and
paragraphs of this Agreement have been added for convenience only and shall not
be deemed to be a part of this Agreement.

             (m) Accession. Any stockholder of the Company who becomes a party
to the Series I Purchase Agreement after the date hereof shall automatically
become a party hereto with respect to the shares of Series I Stock purchased in
connection therewith by delivering to the Company an executed omnibus signature
page in the form attached to such Series I Purchase Agreement, by which such
stockholder agrees to be bound by the obligations imposed under this Agreement,
whereupon such stockholder shall automatically become a party to this Agreement.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]


                                       14

<PAGE>

         Please indicate your acceptance of the foregoing by signing and
returning the enclosed counterpart of this letter, whereupon this Third Amended
and Restated Registration Rights Agreement shall be a binding agreement between
the Company and you.

                                    VIACELL, INC.



                                    By: /s/ Marc D. Beer
                                       ---------------------------------------
                                       Marc D. Beer
                                       Chief Executive Officer

AGREED TO AND ACCEPTED as of the date first above written.

                      [PURCHASER SIGNATURE PAGE TO FOLLOW]


                                       15

<PAGE>

                                  VIACELL, INC.

             SIGNATURE PAGE FOR HOLDERS OF SERIES A PREFERRED STOCK,
               SERIES B PREFERRED STOCK, SERIES C PREFERRED STOCK,
               SERIES D PREFERRED STOCK, SERIES E PREFERRED STOCK,
               SERIES F PREFERRED STOCK, SERIES G PREFERRED STOCK
                          AND SERIES H PREFERRED STOCK


By his, her or its execution and delivery of this signature page, the
undersigned hereby joins in and agrees to be bound by the terms and conditions
of the (i) Second Amended and Restated Investor Rights Agreement dated as of the
date hereof, by and among ViaCell, Inc. (the "Corporation"), the Common
Stockholders and the Investors named therein (the "Investors' Rights
Agreement"), as a "Series A Investor," "Series B Investor," "Series C Investor,"
"Series D Investor," "Series E Investor," "Series F Holder," "Series G Investor"
and/or "Series H Investor" thereunder, (ii) Third Amended and Restated
Registration Rights Agreement dated as of the date hereof, by and among the
Corporation and the Purchasers named therein (the "Registration Rights
Agreement"), as a "Series A Purchaser," "Series B Purchaser," "Series C
Purchaser," "Series D Purchaser," "Series E Purchaser," "Series F Holder,"
"Series G Purchaser" and/or "Series H Purchaser" thereunder, and (iii) Third
Amended and Restated Stockholders Agreement dated as of the date hereof, by and
among the Corporation and the Stockholders named therein (the "Stockholders
Agreement"), as a "Series A Purchaser," "Series B Purchaser," "Series C
Purchaser," "Series D Purchaser," "Series E Purchaser," "Series F Holder,"
"Series G Purchaser" and/or "Series H Purchaser" thereunder, and authorizes this
signature page to be attached to the Investors' Rights Agreement, the
Registration Rights Agreement and the Stockholders Agreement, or counterparts
thereof.



         EXECUTED this 8 day of October, 2001.



                                 Print Name of Investor





                                 By:
                                    -----------------------------------------
                                 Name:
                                       --------------------------------------
                                 Title:
                                       --------------------------------------

                                 Record Address:
                                                -----------------------------


                                 Facsimile No.:
                                               ------------------------------



<PAGE>



                                    EXHIBIT A




SERIES A PURCHASERS:

Charles Kraus and Elaine
Kraus as Joint Tenants
with Rights of Survivorship
6570 Altura Place
Boca Raton, FL 33433

Charles Greenberg
6150 N. Highway 1
Little River, CA 95456

Claire S. Ellis a/k/a
Claire S. Ellis (Greenberg)
6150 N. Highway 1
Little River, CA 95456

SERIES B PURCHASERS:
Claire S. Ellis a/k/a
Claire S. Ellis (Greenberg)
6150 N. Highway 1
Little River, CA 95456

Stanley B. Kraus
500 S.E. 5th Avenue
Mizner Grand Tower, Suite 603
Boca Raton, FL 33432

Irwin Leav
21 Codger Lane
Sudbury, MA 01776

Leslie Clark
82 Arnold Road
Wellesley, MA 02181

Charles Kraus and Elaine
Kraus as Joint Tenants with
Rights of Survivorship
6570 Altura Place
Boca Raton, FL 33433

SERIES C PURCHASERS:

Zero Stage Capital V Limited Partnership
101 Main Street, 17th Floor
Cambridge, MA 02142

Seaflower Health and Technology Fund, L.L.C.
1000 Winter Street
Suite 1000
Waltham, MA 02154

Massachusetts Biotechnology Research Institute, Inc.
One Innovation Drive
Worcester, MA  01605

SERIES D PURCHASERS:
Zero Stage Capital V Limited Partnership
101 Main Street, 17th Floor
Cambridge, MA 02142

Seaflower Health and Technology Fund, L.L.C.
1000 Winter Street,
Suite 1000
Waltham, MA 02154

BB BioVentures L.P.
c/o MPM Asset Management LLC
One Cambridge Center, 9th Floor
Cambridge, MA 02142

TD Javelin Capital Fund, L.P.
2850 Cahaba Road
Suite 240
Birmingham, AL 35223



<PAGE>


SERIES E PURCHASERS:

Zero Stage Capital V Limited Partnership
101 Main Street, 17th Floor
Cambridge, MA 02142

Seaflower Health and Technology Fund, L.L.C.
1000 Winter Street
Suite 1000
Waltham, MA 02154

BB BioVentures L.P.
c/o MPM Asset Management LLC
One Cambridge Center, 9th Floor
Cambridge, MA 02142

TD Javelin Capital Fund, L.P.
2850 Cahaba Road
Suite 240
Birmingham, AL 35223

SERIES F HOLDERS:

Cynthia A. Fisher
186 Park Street
Newton, MA 02458

Cynthia A. Fisher 1999 Family Trust
c/o Marilyn K. Fisher
Box 120 RR4
Mill Road
Selinsgrove, PA 17870

c/o Jonathan Goldstein
Managing Director
c/o TA Associates
125 High Street, Suite 2500
Boston, MA 02110

Marilyn K. Fisher
Box 120 RR4
Mill Road
Selinsgrove, PA 17870

SERIES G PURCHASERS:

BB BioVentures L.P.
c/o MPM Asset Management LLC
One Cambridge Center, 9th Floor
Cambridge, MA 02142

MPM BioVentures Parallel Fund, L.P.
One Cambridge Center, 9th Floor
Cambridge, MA 02142

MPM Asset Management Investors 2000A LLC
One Cambridge Center, 9th Floor
Cambridge, MA 02142

TD Javelin Capital Fund, L.P.
2850 Cahaba Road
Suite 240
Birmingham, AL 35223

TD Javelin Capital Fund II, L.P.
2850 Cahaba Road
Suite 240
Birmingham, AL 35223

TD Lighthouse Capital Fund, L.P.
303 Detroit Street
Suite 301
Ann Arbor, MI 48104

Tullis-Dickerson Capital Focus II, L.P.
One Greenwich Plaza
Greenwich, CT 06830

Zero Stage Capital VI, L.P.
101 Main Street, 17th Floor
Cambridge, MA 02142

SERIES H PURCHASERS:

Nomura International plc
One St. Martin's le Grand
London, EC1A 4NP
United Kingdom

DWS Investment GmbH
Gruneburgweg 113-115
60612 Frankfurt am Main
Germany


<PAGE>


Zero Stage Capital (Cayman) VII, L.P.
101 Main Street, 17th Floor
Cambridge, MA 02142
Attn: Brian Johnson

Zero Stage Capital SBIC VII, L.P.
101 Main Street, 17th Floor
Cambridge, MA 02142
Attn: Brian Johnson

Nomura International plc
One St. Martin's le Grand
London, EC1A 4NP
United Kingdom
Attn: Denise Pollard-Knight

Tullis-Dickerson Capital Focus II, L.P.
One Greenwich Plaza, 3rd Floor
Greenwich, CT 06830
Attn: James L.L. Tullis

TD Origen Capital Fund, L.P.
One Greenwich Plaza, 3rd Floor
Greenwich, CT 06830
Attn: James L.L. Tullis

TD Lighthouse Capital Fund, L.P.
One Greenwich Plaza, 3rd Floor
Greenwich, CT 06830
Attn: James L.L. Tullis

TD Javelin Capital Fund II, L.P.
One Greenwich Plaza, 3rd Floor
Greenwich, CT 06830
Attn: James L.L. Tullis



                                       4