Document:

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                                                                     EXHIBIT 4.6

                                   ALEXANDRIA
                          ARE-One Innovation Drive, LLC
                            135 N. Los Robles Avenue
                                    Suite 250
                           Pasadena, California 91101

                                        February 24, 2000

t.Breeders, Inc.
One Innovation Drive
Worcester, Massachusetts  01605
Attention:  Mr. Morey Kraus

            Re: One Innovation Drive, Worcester, Massachusetts

Ladies and Gentlemen:

      Reference is made to the Letter of Intent, dated November 23, 1999,
entered into between ARE-One Innovation Drive, LLC ("Landlord"), a Delaware
limited liability company, and t.Breeders, Inc. ("Tenant"), a Delaware
corporation, relating to the lease for certain portions of the above-referenced
property.

      1. Future Financings. As additional rent, Landlord, or its affiliate
nominee, shall have the right to purchase not less than $250,000 nor more than
$500,000 worth of any New Securities (as defined below) that Tenant decides to
offer or sell to any investor other than those parties who have invested in
Tenant prior to the date hereof (a "New Investor") at a price and on such other
terms and conditions that are no less favorable to Landlord than those upon
which the New Securities shall be offered or sold by Tenant to a New Investor.
Upon offering to sell or selling any New Securities to a New Investor, Tenant
shall offer to sell the New Securities to Landlord by sending written notice
thereof to Landlord (the "New Securities Notice"). The New Securities Notice
shall describe the provisions of the New Securities in reasonable detail and
shall specify the terms and conditions upon which the New Securities will be
sold by Tenant. Landlord may purchase New Securities for the price and upon the
same terms and conditions specified in the New Securities Notice by sending
written notice to Tenant of its election to do so within 30 business days after
receipt of the New Securities Notice. Any New Securities not purchased by
Landlord may be offered for sale and sold by Tenant on terms and conditions that
are no less favorable to Tenant than those specified in the New Securities
Notice at any time within 120 days after the expiration of the 30 business day
response period. Tenant hereby represents and warrants that it is not now a
party to any agreement, and covenants that it will not enter into any agreement,
that conflicts with the rights granted herein by Tenant to Landlord.
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      "New Securities" means any shares of capital stock of Tenant or any
options, warrants or other securities convertible into or exchangeable or
exercisable for shares of capital stock of Tenant issued in connection with an
offering of equity securities other than (i) securities issued in connection
with a merger or acquisition approved by Tenant's Board of Directors; (ii)
securities and/or options issued to employees, directors, consultants or
scientific advisory board members of Tenant and shares of stock granted upon
exercise of such securities and/or options, under a stock option or other plan
approved by Tenant's Board of Directors up to a maximum of 330,000 shares (or
such greater number of shares as may be approved by Tenant's Board of Directors
in good faith and in accordance with industry practice); and (iii) securities
issued in connection with strategic partnering arrangements between the Company
and entities not affiliated with the Company; provided that the terms of any
such strategic partnering arrangement are determined in good faith by the
Company's Board of Directors to be fair to the Company from a financial point of
view.

      2. Governing Law. The terms and conditions of this agreement shall be
governed by and construed in accordance with Delaware law, without regard to
conflict of law provisions.

      3. Successors and Assigns. The terms and provisions of this agreement
shall be binding upon Landlord and Tenant and their respective successors and
assigns, subject at all times to the restrictions set forth herein.

      4. Counterparts. This agreement may be executed in as many counterparts as
the parties hereto deem necessary or convenient, and each such counterpart shall
be deemed an original but all of which, together, shall constitute but one and
the same document.
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      If the foregoing comports with your understanding of our agreement, then
please execute this letter agreement in the space provided below, whereupon this
letter agreement will become a binding contract. Each party shall become bound
by this letter agreement immediately upon affixing its signature hereto.

                               ARE-ONE INNOVATION DRIVE, LLC,
                               a Delaware limited liability company

                               By:     AREE-HOLDINGS, L.P.,
                                       a Delaware limited partnership,
                                       managing member

                                       By:        ARE-GP HOLDINGS QRS
                                                  CORP., a Delaware corporation,
                                                  General partner

                                                  By:
                                                          Name:
                                                          Title

ACCEPTED AND AGREED AS OF
__________________, 2000

T.BREEDERS, INC.,
a Delaware corporation

By:
      Name:
      Title:<PAGE>
                                                                  EXHIBIT 10.3.2

                                  VIACELL, INC.

                                 January 2, 2004

BY HAND DELIVERY

Mr. Jeffrey Sacher
12 Chanticleer Road
Sudbury, MA 01776

Dear Jeff:

      As we discussed, a decision has been reached that it is appropriate to end
our employment relationship. As a result, following a period of transition, your
employment with ViaCell, Inc. (the "Company") will end on February 2, 2004 (the
"Separation Date"), subject to the terms of this letter. The purpose of this
letter is to confirm the agreement between you and the Company concerning your
transition period and severance arrangements as agreed upon herein and in
accordance with the October 26, 2002 letter to you from Marc Beer, Chief
Executive Officer ("Offer Letter"):

      1. You and the Company agree that your separation from employment is not a
termination "for cause," and hence the Company will provide you with the
following post-employment benefits, pursuant to the Offer Letter:

      (a) The Company will provide you severance pay at your current base rate
of pay for the twelve-month period beginning the business day after your
Separation Date and ending February 2, 2005. Payment will be made at the
Company's regular payroll periods, less taxes and other legally required
deductions, beginning on the Company's next regular payday which is at least
five business days following the date of this agreement, signed by you, is
received by the Company.

      (b) On the Separation Date, the Company will honor the agreement providing
vesting through February 2, 2005, as if still employed, for the two stock option
awards granted to you at your time of hire, namely, those stock option grants
described with particularity in the Offer Letter as "ISO's" and "Performance
Based Options". The additional vesting on the ISOs will be in the amount of
31,250 options, while any additional vesting of Performance Based Options will
be determined if and when the vesting terms are met, as outlined in the Offer
Letter.

      (c) The Company will continue your participation in its group health and
dental for a period of 12 months after the Separation Date, through February 2,
2005, and will continue paying medical and dental premium contributions on your
behalf in accordance with its regular payroll practices throughout that 12-month
period. At the conclusion of the 12-month period ending February 2, 2005, you
may elect to continue your participation and that of your eligible
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dependents in the Company's group health and dental plans to full extent
permissible under the federal law known as "COBRA" by paying the full premium
cost of coverage plus a small administrative fee.

      In consideration of your meeting in full your obligations under the terms
below and under the Confidentiality Agreement described with particularity in
paragraph 2(a) below, the Company agrees as follows (Sections 2-14 hereinafter
referred to as the "Agreement"):

      2. There will be a transition period:

            (a) Provided that you continue to meet the provisions set forth in
paragraphs 2 through 14 hereof and under the Confidential Disclosure Agreement
which you signed in favor of the Company on October 31, 2002 (the
"Confidentiality Agreement"), the Company will continue your employment from the
date of this letter, above, through the Separation Date (the "Transition
Period"), a period of one month. During the Transition Period, the Company will
continue to pay you your base salary, at your current base rate of pay (a total
sum of one-twelfth (1/12) of your annual base salary), and will continue your
participation in the group benefit plans in which you were enrolled as of the
date of this letter, above.

            (b) You agree during the Transition Period to be available for up to
three (3) full business days each week to assist the Company with its transition
of your duties. In doing so, you agree to continue during the Transition Period
to conduct yourself at all times in a courteous and professional manner and to
cooperate fully to assure a smooth transition of your duties. During the
Transition Period, you may arrange time off to seek other employment
opportunities, provided that you make yourself available for up to three (3)
full business days each week. On the Separation Date, you will turn over to me
or my designee all of your work responsibilities.

            (c) In accordance with applicable law, if you have vacation time
accrued but unused on the Separation Date, you will be paid, at your current
base rate, for that vacation time.

      3. You agree to consult with the Company after the Transition Period on an
as needed basis as agreed to by both parties for incremental compensation of
$100 per hour. You agree that your status in regard to the Company in connection
with any such consulting work will be as an independent contractor, and, as
such, you will not be eligible to participate in any Company benefits made
available to its employees, except as expressly provided in paragraph 1 hereof.

      4. You agree that, except as expressly provided in this Agreement, no
further compensation is owed to you. You will not continue to earn vacation or
other paid time off after the Separation Date and, except as provided in
paragraph 2(c) above and in any further right you may have to continue
participation in the Company's group health and benefit plans at your cost under
the federal law known as COBRA following the Separation Date, your participation
in all Company employee benefit plans will end as of the Separation Date, in
accordance with the terms of those plans and programs.
<PAGE>
      5. You agree that, during the Transition Period, you will continue to use
your best efforts to support and promote the interests and reputation of the
Company and that, during the Transition Period and thereafter, you will not
disparage the Company, its business or management, or any of the people or
organizations connected with the Company, and you will not otherwise do or say
anything that could be reasonably expected to disrupt the good morale of the
employees of the Company or otherwise harm the Company's goodwill, business
interests or reputation. In turn, the Company's officers agree not to disparage
you in any way and not to do or say anything that could be reasonably expected
to harm your business interests or reputation and the Company agrees to instruct
employees and members of its Board of Directors not to disparage you in any way
and not to do or say anything that could be reasonably expected to harm your
business interests or reputation.

      6. The Company agrees that in response to any external and internal
inquiries directed to it during the Transition Period or thereafter regarding
the status of your employment with the Company and/or the circumstances of your
separation of employment, it shall respond by providing, in substance, the
following information:

            (a)   The Company and Jeff have agreed that ViaCell needed a CFO
                  with a very deep accounting and public company reporting
                  background.
            (b)   Jeff had made significant contributions to move ViaCell
                  forward.
            (c)   Jeff will be transitioning his responsibilities to a successor
                  over a month or so, and thereafter he will remain open to
                  consult on an as needed basis.
            (d)   Please contact Jeff at (917) 273-5757 for more information.

For purposes of effectuating this paragraph 6, you agree to direct all external
inquiries regarding your employment status with the Company and/or the
circumstances of your separation of employment to Marc Beer, the Company's Chief
Executive Officer, or to Kathleen Hayes, Director of Human Resources.

      7. You agree to return to the Company, no later than the Separation Date,
any and all documents, materials and information related to the business,
whether present or otherwise, of the Company, and all copies, whether in
hardcopy or in electronic or other media, and all keys and other property of the
Company, in your possession or control. You also give the Company assurance that
you have disclosed to the Company all passwords necessary to enable the Company
to access any information which you have password-protected on its computer
network or system.

      8. You hereby acknowledge and confirm your obligations to the Company
under the Confidentiality Agreement, and you agree to abide by all terms and
commitments to which you are bound under the Confidentiality Agreement. You
further understand and agree that any breach by you of the Confidentiality
Agreement will constitute a material breach of this Agreement.
<PAGE>
      9. As an additional Special Severance Benefit, the Company will extend by
nine (9) months the exercise period of your vested stock options, to February 3,
2005 ("Special Severance Benefit").

      10. In exchange for the special severance benefits provided to you
hereunder, including the Special Severance Benefit, to which you would not
otherwise be entitled, on your own behalf and that of your heirs, executors,
administrators, beneficiaries, personal representatives and assigns, you agree
that this Agreement shall be in complete and final settlement of any and all
causes of action, rights or claims, whether known or unknown, that you have had
in the past, now have, or might now have, in any way related to, connected with
or arising out of your employment or its termination or pursuant to Title VII of
the Civil Rights Act, the Americans with Disabilities Act, the Age
Discrimination in Employment Act, the fair employment practices statutes of the
state or states in which you have provided services to the Company or any other
federal, state or local law, regulation or other requirement, and you hereby
release and forever discharge the Company and its subsidiaries and other
affiliates and all of their respective past, present and future directors,
shareholders, officers, members, managers, general and limited partners,
employees, agents, representatives, successors and assigns, and all others
connected with any of them, both individually and in their official capacities,
from any and all such causes of action, rights or claims, except only as to any
rights that you may have to vested benefits.

      11. In exchange for your agreement to the terms of this Agreement, and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the Company agrees that this Agreement shall be in complete
and final settlement of any and all causes of action, rights or claims, whether
known or unknown, that it has had in the past, now has, or might now have
arising out of your employment with the Company, and hereby forever discharges
you, your heirs, executors, administrators, beneficiaries, personal
representatives and assigns from any and all such causes of action, rights, or
claims.

      12. By signing this Agreement, you give the Company assurance that you
have signed it voluntarily and with a full understanding of its terms; that you
have had sufficient opportunity, before signing this Agreement, to consider its
terms and to consult with an attorney, if you wished to do so; and that, in
signing this Agreement, you have not relied on any promises or representations,
express or implied, that are not set forth expressly in this Agreement.

      13. This letter contains the entire agreement between you and the Company
and replaces all prior and contemporaneous agreements, communications and
understandings, whether written or oral, with respect to your employment and its
termination and all related matters, excluding only the Confidentiality
Agreement, which shall remain in full force and effect in accordance with its
terms. This Agreement may not be modified or amended, and no breach shall be
deemed to be waived, unless agreed to in a writing of later date signed by you
and by an expressly authorized representative of the Company.

      14. The Company and you agree that any controversy, claim or dispute
arising out of or relating to Sections 2-13 hereof, either during the Transition
Period or afterwards, between the parties to this Agreement, their successors,
assigns, affiliates or agents, shall be settled by
<PAGE>
arbitration in accordance with the National Rules for the Resolution of
Employment Disputes of the American Arbitration Association ("AAA") then in
effect. Any such arbitration may be initiated within thirty (30) days after
written notification to the other party specifying in sufficient detail the
nature of the dispute hereunder, but in no event later than ninety (90) days
after such written notice. The arbitration shall be conducted in the
Commonwealth of Massachusetts by an arbitrator either mutually agreed upon by
you and the Company or chosen in accordance with the AAA's rules and, unless
otherwise agreed, shall occur on the earliest pair of contiguous dates made
available to the parties by the arbitrator so selected following a period of
discovery of not less than twenty-one (21) days. All aspects of any such
arbitration, including with respect to discovery, shall be conducted in
accordance with the AAA's rules. The Company may not contest its obligations
under the Offer Letter set forth in Section 1 in arbitration, court or any other
legal proceeding.

      If the terms of this Agreement are acceptable to you, please sign, date
and return it to me within ten days of the date you receive it. At the time you
sign and return this letter, it will take effect as a legally-binding agreement
between you and the Company on the basis set forth above under Massachusetts
law. The enclosed copy of this letter, which you should also sign and date, is
for your records.

                                Sincerely,

                                VIACELL, INC.

                                By:   /s/  Kathleen Hayes
                                      --------------------------------------
                                                  Kathleen Hayes
                                            Director of Human Resources

Accepted and agreed:

Signature: /s/ Jeffrey Sacher
           ----------------------------
           Jeffrey Sacher

Date:
     ----------------------------------

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