ADDITIONAL STOCK  In addition, the Company shall grant to you additional
OPTIONS           options ("Performance Based Options") to purchase 50,000
                  shares of Common Stock. The exercise price of the options
                  will equal the fair market value of our Common Stock as
                  determined by the Board of Directors on your date of hire.
                  Such options to become exercisable as to 25% of the shares
                  on each of the fourth, fifth, sixth and seventh anniversary
                  of the date of grant; provided, however, that if at any
                  time within 24 months after the expiration of any lock-up
                  period imposed by the underwriters in connection with the
                  Company's initial public offering of Common Stock, the
                  average of the closing prices of the Company's common stock
                  over a period of 30 consecutive trading days, as reported by
                  the Nasdaq National Market, or any exchange on which the
                  Company's Common Stock is then traded, equals or exceeds
                  $26.00 per share, all of such shares shall become fully
                  vested and exercisable until the expiration of such options
                  or until they sooner terminate in accordance with their terms.
                  The Options shall have a term of ten years, and shall be
                  subject to the terms and conditions most recently approved by
                  the Board for use under the 1998 Equity Incentive Plan.

BENEFITS          Because we care about the well being of our employees, we are
                  pleased to provide you with comprehensive offering of
                  benefits. Our benefits currently include medical, dental,
                  life insurance, three weeks vacation (accrued weekly and
                  pro-rated during your first calendar year of employment),
                  balance benefit, educational assistance and flexible-spending
                  accounts. Additional information about these benefits is out-
                  lined in the enclosed summary.

ELIGIBILITY FOR   The Immigration Reform and Control Act of 1986 requires
EMPLOYMENT        ViaCell to review documentary evidence that you are
                  eligible for employment. This requirement applies to US
                  citizens, as well as foreign nationals. A list of approved
                  documents that are acceptable as verification of employment
                  eligibility are listed on page two of the I-9 form which will
                  be included with your orientation packet. Please bring the
                  appropriate documents with you on your first day of
                  employment.

EMPLOYMENT        While we look forward to a long and mutually beneficial
RELATIONSHIP      relationship, you acknowledge that this letter does not
                  constitute a contract of employment for any particular period
                  of time and does not affect the at-will nature of the
                  employment relationship with the company. Either you or
                  ViaCell have the right to terminate your employment at any
                  time.

We are very excited about the future of ViaCell and believe that the
opportunities presented will allow you significant personal and professional
growth. If you have any questions or concerns, please do not hesitate to
contact me anytime. We look forward to having you join our team!

Sincerely,

/s/ Marc Beer                            Start Date  1/14/02
- ----------------------
Marc Beer
Chief Executive Officer


Please acknowledge your acceptance of this offer by signing a copy of this
document along with the Agreement Related to Intellectual Property and
Confidential Information and faxing it to Kristin Dickson at 617-247-6271. This
offer will remain in effect for a period of seven (7) calendar days from the
date of this letter.


/s/ Robert J. Silverman                      12/20/01
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Signature                                    Date


[Intentionally omitted]                      1/14/02
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Social Security Number                       Start Date