<PAGE>


                                                                   Exhibit 10.36

                                     LEASE

                                by and between

                             21 ERIE REALTY TRUST,

                                   Landlord

                                      and

                              REPROGENESIS, INC.,

                                    Tenant
<PAGE>

                                   ARTICLE I

                                REFERENCE DATA

1.1  SUBJECTS REFERRED TO:

<TABLE>
<S>                                             <C>
APPROXIMATE TERM:                               Ten (10) years plus additional months as set forth
                                                in Section 2.2

BUILDING:                                       The Building of which the Premises are a part,
                                                known and numbered as 21 Erie Street, Cambridge,
                                                Massachusetts, currently containing approximately
                                                49,304 r.s.f. subject to remeasurement in
                                                accordance with the provisions of Section 2.1

BUILDING ADDRESS:                               21 Erie Street
                                                Cambridge, Massachusetts

ANNUAL BASE RENT:                               $10.00 per rentable square foot ("r.s.f.")

INITIAL ESTIMATED ANNUAL
ADDITIONAL RENT:                                $5.50 per r.s.f.

LANDLORD:                                       David E. Clem and David M. Roby, Trustees of 21
                                                Erie Realty Trust

LANDLORD'S MANAGING AGENT'S ADDRESS:            c/o McNeil Management, Inc.
                                                320 Norwood Park South
                                                Norwood, MA  02062

LANDLORD'S REPRESENTATIVE:                      David Clem

LEASE YEAR:                                     Each consecutive period of twelve (12) calendar
                                                months commencing on the Commencement Date.

LOT:                                            The land shown on Exhibit A-1 and more
                                                particularly described on Exhibit A-2 attached
                                                hereto.

OPTIONS TO EXTEND:                              One (1) five (5) year term

PERMITTED USES:                                 General office, research and development,
                                                laboratory and light manufacturing.
</TABLE>
<PAGE>

<TABLE>
<S>                                             <C>
PREMISES:                                       Approximately 32,725 r.s.f. of space in the
                                                Building, as shown on Exhibit A, consisting of
                                                                      ---------
                                                Suites 1 through 5 on the First Floor of the
                                                Building and Suites 4, 5, 6 and 9 on the Second
                                                Floor of the Building (hereinafter referred to as
                                                the "Premises") subject to remeasurement in
                                                accordance with the provisions of Article 2.1.

PUBLIC LIABILITY INSURANCE LIMITS:              Bodily injury:    $10,000,000
                                                Property Damage:  $10,000,000

RIGHT OF FIRST REFUSAL:                         Approximately 18,000 r.s.f. of space on the Second
                                                Floor of the Building and any additional space
                                                added to the Building

TERM COMMENCEMENT DATE:                         (a)  September 25, 1997 as to First Floor, Suite 5
                                                               --
                                                (b)  October 1, 1997 as to Second Floor Suites 4,
                                                     5 and 6;
                                                (c)  January 1, 1998 as to Suites 1, 2, 3 and 4 on
                                                     First Floor and Suite 9 on Second Floor

SECURITY DEPOSIT:                               Four Months Rent, subject to adjustment in
                                                accordance with Section 10.11 hereof).

TENANT:                                         Reprogenesis, Inc.

TENANT'S ADDRESS                                800 Huntington Avenue
(For Notice and Billing):                       Boston, MA  02115

TENANT ALLOWANCE:                               N/A

TENANT'S DESIGN COMPLETION DATE:                N/A

TENANT'S PROPORTIONATE FRACTION:                66.4%, subject to adjustment in connection with
                                                the remeasurement as provided in Section 2.1
                                                hereof.

TERM EXPIRATION DATE:                           December 31, 2007
</TABLE>

                                      -2-
<PAGE>

1.2  EXHIBITS.

     The Exhibits listed below in this section are incorporated in this Lease by
reference and are to be construed as a part of this Lease:

     EXHIBIT A.          Leased Premises
     EXHIBIT A-1.        Lot Site Plan
     EXHIBIT A-2.        Legal Description of Lot
     EXHIBIT B.          Plans and Specifications
     EXHIBIT C.          Rules and Regulations
     EXHIBIT D.          Floor Load Limits
     EXHIBIT E.          Landlord's Services
     EXHIBIT F.          Rentable Square Footage of Suites
                         Comprising the Premises

1.3  TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                    Page
                                                                                    ----
<S>                                                                                 <C>
ARTICLE I     REFERENCE DATA........................................................   1

  1.1         Subjects Referred To:.................................................   1
  1.2         Exhibits..............................................................   3
  1.3         Table Of Contents.....................................................   3

ARTICLE II    PREMISES AND TERM.....................................................   6

  2.1         Premises..............................................................   6
  2.2         Term..................................................................   6
  2.3         Access................................................................   7

ARTICLE III   IMPROVEMENTS..........................................................   7

  3.1         As Is; Initial Construction...........................................   7
  3.2         Preparation Of Premises For Occupancy.................................   7
  3.3         General Provisions Applicable To Construction.........................   8
  3.4         Construction Representatives..........................................   8
  3.5         Alterations And Additions.............................................   8

ARTICLE IV    RENT..................................................................   9

  4.1         Fixed Rent............................................................   9
  4.2         Additional Rent.......................................................  10
    4.2.1     Real Estate Taxes.....................................................  10
    4.2.2     Insurance.............................................................  11
    4.2.3     Utilities.............................................................  13
    4.2.4     Common Area Maintenance and Expenses..................................  14
</TABLE>

                                      -3-
<PAGE>

<TABLE>
<S>                                                                                   <C>
    4.2.5     Payments on Account of Taxes, Insurance and Utilities.................  18
    4.2.6     Equitable Adjustment of Additional Rent...............................  19

  4.3         Late Payment Of Rent..................................................  19

ARTICLE V     TENANT'S ADDITIONAL COVENANTS.........................................  19

  5.1         Affirmative Covenants.................................................  19
    5.1.1     Perform Obligations...................................................  19
    5.1.2     Occupancy and Use.....................................................  19
    5.1.3     Repair and Maintenance................................................  20
    5.1.4     Compliance with Law...................................................  21
    5.1.5     Tenant's Work.........................................................  23
    5.1.6     Indemnity.............................................................  24
    5.1.7     Landlord's Right to Enter.............................................  24
    5.1.8     Personal Property at Tenant's Risk....................................  25
    5.1.9     Payment of Landlord's Cost of Enforcement.............................  25
    5.1.10    Yield Up..............................................................  25
    5.1.11    Estoppel Certificate..................................................  25
    5.1.12    Landlord's Expenses Re Consents.......................................  26
    5.1.13    Rules and Regulations.................................................  26
    5.1.14    Loading...............................................................  26
    5.1.15    Holdover..............................................................  26

  5.2         Negative Covenants....................................................  27
    5.2.1     Assignment and Subletting; Mortgaging.................................  27
    5.2.2     Nuisance..............................................................  29

ARTICLE VI    CASUALTY OR TAKING....................................................  30

  6.1         Termination...........................................................  30
  6.2         Restoration...........................................................  30
  6.3         Award.................................................................  30

ARTICLE VII.  DEFAULTS..............................................................  31

  7.1         Events Of Default.....................................................  31
  7.2         Remedies..............................................................  32
  7.3         Remedies Cumulative...................................................  33
  7.4         Landlord's Right To Cure Defaults.....................................  33
  7.5         Effect Of Waivers Of Default..........................................  33
  7.6         No Accord And Satisfaction............................................  33

ARTICLE VIII  MORTGAGES.............................................................  34

  8.1         Rights Of Mortgage Holders............................................  34
  8.2         Priority Of Lease; Subordination......................................  34
</TABLE>

                                      -4-
<PAGE>

<TABLE>
<S>                                                                                   <C>
  8.3         Lease Amendments......................................................  35
  8.4         No Existing Mortgage..................................................  35

ARTICLE IX    LANDLORD'S ADDITIONAL COVENANTS.......................................  35

  9.1         Affirmative Covenants.................................................  35
    9.1.1     Perform Obligations...................................................  35
    9.1.2     Repairs...............................................................  36
    9.1.3     Compliance with Law...................................................  36
    9.1.4     Indemnity.............................................................  36
    9.1.5     Estoppel Certificate..................................................  37
    9.1.6     Utilities.............................................................  37

ARTICLE X     MISCELLANEOUS PROVISIONS..............................................  37

  10.1        Notices From One Party To The Other...................................  37
  10.2        Quiet Enjoyment.......................................................  37
  10.3        Easements; Changes To Lot Lines.......................................  37
  10.4        Lease Not To Be Recorded..............................................  38
  10.5        Bind And Inure; Limitation Of Landlord's Liability....................  38
  10.6        Acts Of God...........................................................  38
  10.7        Landlord's Default....................................................  38
  10.8        Brokerage.............................................................  39
  10.9        Applicable Law And Construction.......................................  39
  10.10       Submission Not An Offer...............................................  39
  10.11       Security Deposit......................................................  39
  10.12       Options To Extend.....................................................  40
  10.13       Right Of First Refusal................................................  41
  10.14       Confidential Information..............................................  42
  10.15       Signage...............................................................  42
  10.16       Parking...............................................................  42
 </TABLE>

                                      -5-
<PAGE>

                                  ARTICLE II

                               PREMISES AND TERM

2.1  PREMISES.

     Landlord hereby leases and demises to Tenant and Tenant hereby leases from
Landlord, subject to and with the benefit of the terms, covenants, conditions
and provisions of this Lease, the Premises.  Tenant shall have, as appurtenant
to the Premises, the right to use in common with others entitled thereto (i) the
common facilities included in the Building or on the Lot, and (ii) the building
service fixtures and equipment serving the Premises.  In addition, Landlord
together with the affiliates referred to in Section 10.16, hereby grant Tenant
the parking rights more particularly set forth in Section 10.16, and Tenant
agrees to lease certain parking spaces, all subject to the terms and conditions
of Section 10.16.

     The rentable area of the Premises shall be measured upon completion of the
second floor corridor in accordance with the Building owners and Managers
Association International ANSI Z 65.1 Method @ 1990 (the "BOMA Method") and said
calculation shall be used, retroactive to the Term Commencement Date, as the
actual rentable square footage of the Premises as defined herein and in Article
1.1.

     Landlord reserves the right from time to time, upon reasonable advance
notice (except in the case of an emergency), without unreasonable interference
with Tenant's use, (a) to install, repair, replace, use, maintain and relocate
for service to the Premises and to other parts of the Building or either,
building service fixtures and equipment wherever located in the Building,
provided, however, that the Annual Fixed Rent, Additional Rent (as defined in
Section 4.2 hereof) and other charges payable hereunder by Tenant shall be
proportionally reduced in the event that any such installation or relocation of
service reduces the usable floor area of the Premises (other than a temporary
reduction to accommodate installation, repair, replacement, maintenance and
relocation of such service) (in no event, however, shall such activities by
Landlord cause a material reduction in the square footage of the Premises) ; and
(b) to alter or relocate any common facilities, provided that in all events (1)
substitutions are in compliance with applicable zoning and other laws and (2)
substitutions are substantially equivalent.  Landlord shall give Tenant a
reasonable opportunity to have any such access by Landlord described in this
Section 2.1 supervised by a Tenant representative.

     The Premises shall be subject to expansion in accordance with the terms of
Section 10.13.

2.2  TERM.

     To have and to hold for a period (the "Term") commencing on the Term
Commencement Date (excluding, however, Tenant's occupying of Suite 2, Second
Floor of the Building) as set forth in Section 1.1 and continuing until the Term
Expiration Date, unless sooner terminated as provided in Section 3.2 or in
Article VII, and subject to extension in accordance with the terms of Section
10.12 hereof.

                                      -6-
<PAGE>

2.3  ACCESS.

     Tenant shall have access to the Building by separate entrance to the
Building on Erie Street as shown on the Plans and Specifications (as defined
hereinafter) and the Premises twenty-four (24) hours a day, seven (7) days a
week, three hundred sixty-five (365) days a year.  Tenant's access after Normal
Business Hours (as defined hereafter) is by a telephone intercom system
installed in the Building.  Tenant is responsible for security of the Premises
after Normal Business Hours.  "Normal Business Hours" shall mean the hours of
7:00 a.m. through 6:00 p.m. Monday through Friday and no hours on legal
holidays, Saturdays and Sundays.

                                  ARTICLE III

                                 IMPROVEMENTS

3.1  AS IS; INITIAL CONSTRUCTION.

     Tenant acknowledges that it has had an opportunity to inspect the Premises.
The Premises shall be delivered to Tenant As Is, Where Is, with all faults and
without representation, warranty or guaranty of any kind by Landlord to Tenant.
Nothing in the preceding sentence is intended to relieve Landlord of any of its
maintenance and repair responsibilities set forth in this Lease.  Tenant at its
sole cost and expense shall prepare all construction drawings and specifications
(the "Plans and Specifications") shown on Exhibit B for initial improvements
                                          ---------
("Leasehold Improvements") to the Premises and submit the same to Landlord for
Landlord's review and written approval, which approval shall not be unreasonably
withheld or delayed.  The approval rights of Landlord and the construction
obligations of Landlord are subject to the remaining provisions of this Article
III.

3.2  PREPARATION OF PREMISES FOR OCCUPANCY.

     Tenant agrees to diligently perform the Leasehold Improvements and to use
best efforts to complete the Leasehold Improvements.  Landlord shall permit
Tenant access to the Building and the Premises for purposes of constructing the
Leasehold Improvements immediately upon full execution of this Lease, which
occupancy by Tenant shall be subject to all of the terms and conditions of the
Lease.

     Tenant shall have thirty (30) days from the date of execution of this Lease
to engage Aries Engineering and/or any other environmental engineering firm
selected by Tenant for the purpose of conducting a Phase-I Environmental Site
Assessment (the "Site Assessment") of the Premises.  Landlord shall provide
reasonable access to the Premises for the purpose of conducting the Site
Assessment.  In the event the Site Assessment is unsatisfactory to Tenant in its
reasonable discretion, Tenant shall have the right within said thirty (30) days
to terminate this Lease by written notice to Landlord ("Notice of Termination").
Tenant's right to terminate this Lease shall be Tenant's sole and exclusive
remedy without further recourse to either party.  In the event Tenant does not
deliver the Notice of Termination to Landlord, Tenant shall be deemed to have
waived its right to terminate the Lease under this Section 3.2.

                                      -7-
<PAGE>

3.3  GENERAL PROVISIONS APPLICABLE TO CONSTRUCTION.

     All construction work required or permitted by this Lease, shall be done by
Tenant in a good and workmanlike manner and in compliance with all applicable
laws and all lawful ordinances, regulations and orders of any governmental
authority and insurers of the Building and the Lot (provided that Landlord shall
be responsible for such compliance with respect to the Building, other than the
Premises).  Landlord may inspect the work of Tenant at reasonable times and
shall give notice of observed defects.

3.4  CONSTRUCTION REPRESENTATIVES.

     Each party authorizes the other to rely in connection with their respective
rights and obligations under this Article III upon approval and other actions on
the party's behalf by any person designated by such party as its Representative
by notice to the party relying.

3.5  ALTERATIONS AND ADDITIONS.

     This Section 3.5 shall apply before and during the Term and shall apply to
the initial Leasehold Improvements.  Tenant shall not make any alterations and
additions to the Premises except in accordance with the Plans and Specifications
first approved by Landlord, which approval shall not be unreasonably withheld or
delayed.  However, any alterations or additions that do not affect structural or
exterior elements of the Building or Building mechanical systems, not exceeding
$25,000.00 in value may be performed without being required to obtain such
approval.  However, Tenant shall be required to ascertain from Landlord what
Landlord will require Tenant to remove from the Premises upon termination of the
Lease prior to construction of such alterations or improvements.  Landlord shall
not unreasonably withhold its approval of Tenant's Plans and Specifications
provided that, if any alterations or additions affect structural or exterior
elements of the Building or Building mechanical systems, said alterations will
not materially interfere with the use of the Building by other tenants and
occupants and is in compliance with all applicable codes, laws, regulations and
ordinances.  At the time Landlord approves Tenant's Plans and Specifications,
Landlord must advise Tenant which improvements Tenant shall be responsible for
removing upon termination of the Lease.  Landlord agrees that Tenant may, but
shall not be required to, remove any of its initial installations and Leasehold
Improvements and that all of said Leasehold Improvements that Landlord does not
require Tenant to remove and Tenant elects not to remove, shall become the
property of the Landlord upon expiration or termination of this Lease.  If,
after completion of Tenant's initial Leasehold Improvements as approved by
Landlord, Tenant alters substantially the initial installations and Leasehold
Improvements in the Premises and such alterations involve substantial demolition
costs, Landlord may require Tenant to demolish the same at the end of the Term.
All of Tenant's alterations and additions including initial Tenant Improvements
and installation and delivery of telephone systems, computer systems,
furnishings, and equipment shall be performed in such manner, and by such
persons as shall maintain harmonious labor relations and not cause any damage to
the Building or interference with Building construction or operation and, except
for installation of furnishings, equipment and telephone systems, and except as
otherwise expressly set forth herein, shall be performed by general contractors
first approved by Landlord.  Landlord shall not unreasonably withhold or delay
its approval of Tenant's contractor and subcontractors provided that said
contractor in Landlord's reasonable opinion, uses first quality materials and

                                      -8-
<PAGE>

provides good workmanship and services.  Before commencing any work Tenant
shall: secure all licenses and permits necessary therefor (Landlord agreeing to
reasonably cooperate with Tenant to obtain such licenses and approvals provided
that Tenant pay all of Landlord's out-of-pocket expenses, if any, incurred in
connection therewith); deliver to Landlord a statement of the names of all its
contractors and subcontractors (the identity of which must have been previously
approved by Landlord as hereinabove contemplated) and the estimated cost of all
labor and material to be furnished by them; and cause each contractor to carry
(i) workmen's compensation insurance in statutory amounts covering all the
contractor's and subcontractor's employees and (ii) comprehensive public
liability insurance with such limits as Landlord may reasonably require, but in
no event less than a combined single limit of $3,000,000 (all such insurance to
be written in companies reasonably approved by Landlord and insuring Landlord
and Tenant as well as the contractors), and to deliver to Landlord certificates
of all such insurance.  Tenant agrees to pay promptly when due, and to defend
and indemnify Landlord from and against, the entire cost of any work done on the
Premises by Tenant, its agents, employees or independent contractors, and not to
cause or permit any liens for labor or materials performed or furnished in
connection therewith to attach to the Building or the Lot and to discharge
within ten (10) days after notice to Tenant or after Tenant becomes aware of the
existence of any such liens which may so attach.  Tenant shall pay to Landlord,
as additional rent, a sum equal to all reasonable out-of-pocket costs reasonably
incurred by Landlord in reviewing and approving any alterations or additions.

                                  ARTICLE IV

                                     RENT

4.1  FIXED RENT.

     (a)  Monthly Installments; Definitions.  Tenant covenants and agrees to pay
          ---------------------------------
rent to Landlord, without any offset or reduction whatsoever (except as may be
made in accordance with the express provisions of this Lease), at the address of
Landlord's Managing Agent or at such other place or to such other person or
entity as Landlord may by notice to Tenant from time to time direct, at the
Annual Base Rent Rate set forth in Article I, in, equal installments equal to
1/12th of the Annual Base Rent Rate in advance on the first day of each calendar
month included in the Term; and for any portion of a calendar month at the
beginning or end of the Term, at that rate payable in advance for such portion.

     Landlord and Tenant hereby agree that the Annual Base Rent Rate shall be
initially based on square footage calculations set forth in Section 1.1, based
on the r.s.f of the Premises from time to time.  Attached hereto as Exhibit F is
a list of suites and their respective r.s.f.  Upon the recalculation of the
r.s.f. of the Premises, a reconciliation shall be made between Landlord and
Tenant.

     (b)  Adjustment for CPI.  On January 1, 2003 (the "Adjustment Date"), the
          ------------------
Annual Base Rent Rate shall be increased by multiplying said rate by a fraction,
the numerator of which shall be the Price Index (as hereinafter defined) most
recently established prior to the Adjustment Date, and the denominator of which
shall be the Base Price Index (as hereinafter defined), compounded monthly over
the first five (5) years of the Term of this Lease.  As used herein, the

                                      -9-
<PAGE>

term "Price Index" shall mean and refer to the "Consumer Price Index for Urban
Wage Earners and Clerical Workers, for the Boston, Massachusetts area, All Items
(1982-84=100)" published by the Bureau of Labor Statistics of the United States
Department of Labor or successor or substitute index appropriately adjusted, and
the term "Base Price Index" shall mean and refer to the Price Index most
recently established prior to January 1, 1998. In the event the Price Index (or
a successor or substitute index) shall not be published for the City of Boston,
or for the months indicated above, the corresponding index for the United States
City Average (and if this is not available, a reliable governmental or other
nonpartisan publication evaluating similar or equivalent information as used in
the Price Index) shall be used. In the event the Price Index ceases to use the
1982-84 average of 100 as the basis of calculation, or if a substantial change
is made in the terms or numbers of items contained in the Price Index, then the
Price Index shall be adjusted to the figure that would have been arrived at had
the manner of computing the Price Index in effect at the date of this Lease not
been changed.

4.2  ADDITIONAL RENT.

     In order that the Fixed Rent shall be absolutely net to Landlord, Tenant
covenants and agrees to pay, as Additional Rent, without any offset or reduction
whatsoever (except as may be made in accordance with the express provisions of
the Lease), Tenant's proportionate fraction of real estate taxes, municipal or
state betterment assessments, insurance costs, common area utility charges and
Annual Maintenance Charges with respect to the Premises as provided in this
Section 4.2 as follows:

     As used herein, the term "Estimated Annual Additional Rent" shall mean and
refer to Landlord's estimate of the total amount of Additional Rent which may be
due from Tenant for any particular Lease Year.  Landlord shall furnish Tenant
with a statement as soon as reasonably practicable after the commencement of
each Lease Year setting forth the amount of Landlord's Estimated Annual
Additional Rent for such Lease Year.  Landlord's good faith estimate of the
Estimated Annual Additional Rent for the first fiscal year of the Term is set
forth in Section 1.1 as the "Initial Estimated Annual Additional Rent".

     4.2.1     Real Estate Taxes.  Subject to Section 4.2.6, Tenant shall pay
directly to the Landlord Tenant's Proportionate Fraction of: (i) all ad valorem
real estate taxes, betterment assessments (special or otherwise), levies, fees,
water and sewer rents and charges, and all other similar government levies and
charges, general and special, ordinary and extraordinary, foreseen and
unforeseen, imposed or levied upon or assessed against the Building in which the
Premises are a part or the Lot and allocable to the Term hereof (collectively
"taxes and assessments" or if singular "tax or assessment").  For each tax or
assessment period, or installment period thereof, wholly included in the Term,
all such payments (prorated if the Term includes any portion of such tax and
assessment period, or installment period thereof) shall be made by Tenant not
later than the later of (i) thirty (30) days after invoice from Landlord to
Tenant accompanied by the relevant substantiation or (ii) five (5) days prior to
the last date on which the same may be paid without interest or penalty.  At
Landlord's option, Tenant shall pay taxes and assessments in accordance with
Section 4.2.5 hereof.

     In the event that Tenant, requests that Landlord apply for any abatement
of, or otherwise contest, any tax or assessment, Landlord shall file such
abatement or otherwise contest such tax

                                     -10-
<PAGE>

or assessment and shall diligently pursue the same to completion, provided that
(i) Landlord receives notice of such request from Tenant at least 30 days prior
to the last day on which such abatement or contest may validly be made under
applicable law, and (ii) the reasonable substantiated expenses of such
proceedings, including, without limitation, any attorneys' fees incurred as a
result thereof, shall be included in the Annual Maintenance Charge of the then
current fiscal year.

     Nothing contained in this Lease shall, however, require Tenant to pay any
income taxes, excess profits taxes, excise taxes, franchise taxes ("Excluded
Taxes"), estate, succession, inheritance or similar transfer taxes, provided,
however, that if at any time during the Term the present system of ad valorem
taxation of real property shall be changed so that in lieu of the whole or any
part of the ad valorem tax on real property, there shall be assessed on Landlord
a capital levy or other tax on the gross rents received with respect to the
Building or the Lot, or all of them, or a federal, state, county, municipal, or
other local income, franchise, excise or similar tax, assessment, levy or charge
(distinct from any now in effect) measured by or based, in whole or in part,
upon gross rents, then any and all of such taxes, assessments, levies or
charges, to the extent so measured or based ("Substitute Taxes"), shall
constitute real estate taxes payable under the Section 4.2.1; provided, however,
that (i) the inclusion of the aforesaid Substitute Taxes shall be limited to the
amount thereof as computed at the rates that would be payable if the Building
and Lot were the only property of Landlord, and (ii) only that portion of the
Substitute Taxes in excess of the Excluded Taxes shall be payable by Tenant.
Landlord shall furnish to Tenant a copy of any notice of any public, special or
betterment assessment received by Landlord concerning the Building or Lot.

     4.2.2     Insurance.

     4.2.2.1   Insurance Taken Out by Tenant.

               Tenant shall take out and maintain throughout the Term the
following insurance:

               (a)  Comprehensive general liability insurance indemnifying
Landlord and Tenant against all claims and demands for (i) injury to or death of
any person or damage to or loss of property, on the Premises or adjoining walks,
streets or ways, or connected with the use, condition or occupancy of any
thereof unless caused by the negligence of Landlord or its servants or agents,
or (ii) any negligence or misconduct of Tenant or its agents, contractors,
licensees, or sublessees, in amounts which shall, at the beginning of the Term,
be at least equal to the limits set forth in Section 1.1, and, from time to time
during the Term, shall be for such higher limits, if any, as are customarily
carried in the area in which the Premises are located on property similar to the
Premises and used for similar purposes; and shall be written on the "Occurrence
Basis" and include Host Liquor liability insurance; and

               (b)  Worker's compensation insurance with statutory limits
covering all of the Tenant's employees working on the Premises.

                                     -11-
<PAGE>

     4.2.2.2   Insurance Taken Out by Landlord.

               Landlord shall take out and maintain throughout the Term the
following insurance:

               (a)  Comprehensive general liability insurance for the Building
and Lot of the same nature and type as described in Section 4.2.2.1(a) of this
Lease, and with the same policy limits; and

               (b)  All risk, fire and casualty insurance on a 100% replacement
cost basis, together with rental loss coverage and, if the Building is located
in a flood zone, flood coverage to the extent the same is available, insuring
the Building and its rental value and

               (c)  Insurance against loss or damage from sprinklers and from
leakage or explosions or cracking of boilers, pipes carrying steam or water, or
both, pressure vessels or similar apparatus, in the so-called "broad form", in
such amounts as are customary and commercially reasonable for buildings in the
Cambridge, Massachusetts area which are of like kind and quality to the Building
and have laboratory uses, and insurance against such other hazards and in such
amounts as may from time to time be required by any bank, insurance company or
other lending institution holding a first mortgage on the Building and Lot.

     Landlord shall have no obligation to insure Tenant's personal property or
chattels, including without limitation, Tenant's trade fixtures.

     4.2.2.3   Tenant Reimbursement of Insurance Taken out by Landlord.

               Tenant shall from time to time reimburse Landlord within thirty
days (30) of Landlord's invoice for Tenant's Proportionate Fraction of
Landlord's costs incurred in providing the insurance provided pursuant to
Section 4.2.2.2 of this Lease, equitably prorated in the case of blanket
policies to reflect the insurance coverage reasonably attributable to the
Building and Lot, and provided further that Tenant shall reimburse Landlord for
all of Landlord's costs incurred in providing such insurance which is
attributable to any special endorsement or increase in premium resulting from
the business or operations of Tenant, and any special or extraordinary risks or
hazards resulting therefrom, including without limitation, any risks or hazards
associated with the generation, storage and disposal of medical waste. Landlord
shall collect any extra premium from other tenants of the Building to the extent
caused by such other tenant's business operations. At Landlord's option, Tenant
shall reimburse Landlord for insurance costs in accordance with Section 4.2.5
hereof.

     4.2.2.4   Certain Requirements Applicable to Insurance Policies.

               Policies for insurance provided for under the provisions of
Sections 4.2.2.2(b) and 4.2.2.2(c) shall, in case of loss, be first payable to
the holders of any mortgages on the Building and Lot under a standard
mortgagee's clause and shall be deposited with the holder of any mortgage or
with Landlord, for application under this Lease. All policies for insurance
required to be obtained by either party under the provisions of Section 4.2.2
shall be obtained from responsible companies qualified to do business in the
state in which the Premises are located and in good standing therein, which
companies and the amount of insurance allocated

                                     -12-
<PAGE>

thereto shall be subject to Landlord's approval. Each party agrees to furnish
the other with certificates of all such insurance which such party is obligated
to obtain pursuant to Section 4.2.2 prior to the beginning of the Term hereof
and with renewal certificates at least thirty (30) days prior to the expiration
of the policy they renew. In addition, each party agrees to furnish the other
with any policies of insurance which the other is obligated to obtain hereunder,
including any renewal policies, upon request of the other party (provided that
Tenant may redact from such policies any Confidential Information, as defined in
Section 10.14 hereof). Each such policy required to be maintained by Tenant
shall name Landlord and Landlord's Managing Agent as additional insureds and
shall be noncancellable with respect to the interest of Landlord, Landlord's
Managing Agent and such mortgagees without at least 30 days' prior written
notice thereto.

     4.2.2.5   Waiver of Subrogation.

               All property insurance which is carried by either party with
respect to the Premises whether or not required, shall include provisions which
either designate the other party as one of the insured or deny to the insurer
acquisition by subrogation of rights of recovery against the other party to the
extent such rights have been waived by the insured party prior to occurrence of
loss or injury, insofar as, and to the extent that such provisions may be
effective without making it impossible to obtain insurance coverage from
responsible companies qualified to do business in the state in which the
Premises are located (even though extra premium may result therefrom) and
without voiding the insurance coverage in force between the insurer and the
insured party. In the event that extra premium is payable by either party as a
result of this provision, the other party shall reimburse the party paying such
premium the amount of such extra premium. If at the request of one party, this
non-subrogation provision is waived, then the obligation of reimbursement shall
cease for such period of time as such waiver shall be effective, but nothing
contained in this Section 4.2.2.5 shall derogate from or otherwise affect
releases elsewhere herein contained of either party for claims. Each party shall
be entitled to have duplicates or certificates of any policies containing such
provisions. Each party hereby waives all rights of recovery against the other
for loss or injury against which the waiving party is protected by insurance
containing said provisions, reserving, however, any rights with respect to any
excess of loss or injury over the amount recovered by such insurance. Tenant
shall not acquire as insured under any insurance carried on the Premises under
the provisions of this Section 4.2.2 any right to participate in the adjustment
of loss or to receive insurance proceeds and agrees upon request promptly to
endorse and deliver to Landlord any checks or other instruments in payment of
loss in which Tenant is named as payee.

     4.2.3     Utilities.

               Tenant shall pay directly to the proper authorities charged with
the collection thereof all charges for water, sewer, gas, electricity, telephone
and other utilities or services used or consumed on the Premises, whether called
charge, tax, assessment, fee or otherwise, including, without limitation, water
and sewer use charges and taxes, if any, all such charges to be paid as the same
from time to time become due. Upon Tenant's request, Landlord shall install at
Tenant's expense separate meters to measure Tenant's consumption of any utility
servicing the Premises. Tenant and Landlord agree that check meters shall be
installed in the other tenant's premises at Landlord's or such other tenant's
expense. A portion of the Premises (Suite 5, Floor

                                     -13-
<PAGE>

One) is presently metered separately for electricity. If Tenant is not charged
directly by the respective utility for any of such utilities or services are
being provided to the common areas of the Building and/or Lot, Tenant shall from
time to time, within twenty (20) days of receipt of Landlord's invoice therefor
accompanied by substantiation reasonably acceptable to Tenant, pay to Landlord
Tenant's Proportionate Fraction of the total of such charges for the Building
and Lot, provided that if said utilities or services are provided to less than
all of the rentable space in the Building, Tenant shall pay its share of said
charges based upon the actual consumption shown on any separate meter for such
utility or service, and, in the event there is no such separate meter, based
upon the area of the Premises relative to the area of the entire space to which
utilities are provided, or such greater amount required, in Landlord's
reasonable judgment, by Tenant's disproportionate use of utilities, and provided
further that, at Landlord's option, all such charges payable by Tenant to
Landlord for common area utilities and services shall be payable by Tenant in
accordance with Section 4.2.5. Landlord shall not be liable for any interruption
or failure in the supply of any such utilities to the Premises; provided,
however, that in the event such loss or failure is due to causes other than
Tenant's negligence or willful misconduct. Tenant shall be entitled to abatement
of rent and Additional Rent from and after the third (3rd) day of such
interruption. Without limitation of the foregoing, in the event of a Casualty or
Taking, if Landlord's architect reasonably determines that utilities will not be
repaired or restored so as to be available at the Utility Switching Points
within one year after the occurrence of such Casualty or Taking, then Tenant
shall have the right to terminate this Lease by notice given within thirty (30)
days after the date of such determination.

     4.2.4     Common Area Maintenance and Expenses.

               Landlord shall maintain the common areas of the Lot and the
common areas of interior and exterior of the Building in a clean and orderly
condition in accordance with Exhibit E, except to the extent repairs or
                             ---------
maintenance are required due to Tenant's negligence or willful misconduct (in
which case Landlord may effect such repairs or maintenance and charge the entire
reasonable cost thereof to Tenant as Additional Rent). Notwithstanding the
foregoing, it is expressly understood and agreed that Landlord shall have no
liability or responsibility for the storage, containment or disposal of any
hazardous or medical waste generated, stored or contained by Tenant, Tenant
hereby agreeing to store, contain and dispose of any and all such hazardous or
medical waste at Tenant's sole cost and expense in accordance with the
provisions of Article V hereof. Tenant shall pay to Landlord as Additional Rent
the Annual Maintenance Charge computed and payable as follows:

          (1)  The Annual Maintenance Charge shall be equal to the sum of the
          Annual Lot Maintenance Charge and the Annual Building Maintenance and
          Operation Charge as hereinafter defined and exclude the Exclusions
          from Common Area Maintenance and Expenses as hereinafter defined.

               (a)  The Annual Lot Maintenance Charge shall be equal to the
          product obtained by multiplying (x) the reasonable costs incurred by
          Landlord during the fiscal year (as hereinafter defined) for which the
          Annual Maintenance Charge is being computed (the "Current Fiscal
          Year") in providing Lot maintenance, including without limitation
          landscaping, street lighting, security (if required, in Landlord's
          reasonable judgment), maintenance and snow plowing, maintenance

                                     -14-
<PAGE>

          of Lot, common signage, maintenance of common utilities, and
          management fees not exceeding a competitive market rate management fee
          with reference to similar buildings in Cambridge, by (y) Tenant's
          Proportionate Fraction.

               (b)  The Annual Building Maintenance and Operation Charge shall
          be equal to Tenant's Proportionate Fraction of the reasonable costs
          incurred by Landlord during the Current Fiscal Year in providing
          Building maintenance, including without limitation repair, maintenance
          and cleaning of common facilities in the Building, and maintenance and
          repairing of all common heating, plumbing, electrical, air
          conditioning and mechanical fixtures and equipment serving the
          Building generally or the Premises, elevators, trash dumpster rental,
          trash removal, recycling, performance of such other tasks as Tenant
          shall request and Landlord shall agree to perform, management fees
          (exclusive of leasing and sale commissions, fees paid in connection
          with tenant improvement costs, and such other fees or commissions paid
          in connection with the leasing, re-leasing, extension or renewal of
          leases for the Building or the Lot) as previously set forth in (a)
          above not exceeding a competitive market rate management fee with
          reference to similar buildings in Cambridge and amortization of
          equipment to the extent used for Building maintenance.

               (c)  In no event shall any of the following be included in Annual
          Maintenance Lot Charge or Annual Building Maintenance and Operation
          Charge:

                    (i)    the cost of alterations, capital improvements and
               other items which under generally accepted accounting principles
               are properly classified as capital expenditures;

                    (ii)   any tenant work performed for, or alteration of
               space leased to, Tenant or other tenants or occupants of the
               Building, whether such work or alteration is performed for the
               initial occupancy of such tenant or occupant or thereafter;

                    (iii)  any cash or other consideration paid by Landlord on
               account of, with respect to or in lieu of the tenant work or
               alterations described in clause (ii) above;

                    (iv)   ground rent;

                    (v)    depreciation or amortization;

                    (vi)   repairs necessitated by the negligence of Landlord
               or other tenants or occupants;

                    (vii)  costs of the negotiation of and enforcement of
               leases;

                    (viii) interest on indebtedness or any costs of financing
               or refinancing the Building or any capital expenditures excluded
               hereby;

                                     -15-
<PAGE>

                    (ix)     compensation paid to officers and executives of
               Landlord above the grade of building manager;

                    (x)      leasing commissions, advertising and promotional
               expenses;

                    (xi)     legal fees, or other professional or consulting
               fees in connection with any items to be excluded hereby;

                    (xii)    the cost of repairs incurred by reason of fire or
               other casualty or condemnation to the extent that either (a)
               Landlord is compensated therefore through proceeds of insurance
               or condemnation; (b) Landlord failed to obtain insurance against
               such fire or casualty, if such insurance was generally carried by
               the owners of similar buildings in Cambridge; or (c) Landlord is
               not fully compensated therefore due to the coinsurance provisions
               of its insurance policies on account of Landlord's failure to
               obtain a sufficient amount of coverage against such risk;

                    (xiii)   the cost of the future renovations or additions to
               the Building, except to the extent the same is offset by cost
               saving measures to the tenants in the Building;

                    (xiv)    overtime HVAC costs whether or not charged
               separately to other Building tenants;

                    (xv)     the cost of performing additional services or
               installations to or for tenants to the extent that such service
               exceeds that provided by Landlord to Tenant without charge
               hereunder;

                    (xvi)    any amounts payable by Landlord by way of indemnity
               or for damages or which constitute a fine, interest or penalty;

                    (xvii)   any improvement installed or work performed or any
               other cost or expense incurred by Landlord in order to comply
               with the requirements for obtaining of, or renewal of, a
               certificate of occupancy for the Building or for any other tenant
               space therein;

                    (xviii)  any cost representing an amount paid for services
               or materials to a related person, firm or entity to the extent
               such amount exceeds the amount that would be paid for such
               services or materials at the then existing market rates therefor
               to an unrelated person, firm or corporation; and

                    (xix)    expenses, costs and disbursements relating to or
               arising in any way, directly or indirectly, from the handling,
               removal, treatment, disposal or replacement of asbestos, asbestos
               containing materials or other hazardous materials in the Building
               and/or the Lot.

                                     -16-
<PAGE>

     Tenant shall make payments on account of the Annual Maintenance Charge
monthly in advance on the first day of each calendar month during the Term.  At
the beginning of every fiscal year, Landlord shall deliver to Tenant its
reasonable estimate of the Annual Maintenance Charge (the "Estimated Annual
Maintenance Charge") for the said fiscal year which estimate may include a
reasonable contingency of up to 5%, and Tenant shall make payments on account of
the Annual Maintenance Charge monthly in advance on the first day of each
calendar month during the Term in the amount of one-twelfth of the Estimated
Annual Maintenance Charge.  Landlord reserves the right to reasonably re-
estimate and modify the Estimated Annual Maintenance Charge by notice to Tenant
once annually on or about July 1 of each Lease Year (the "Additional Rent
Adjustment Date"), and Tenant's payments shall thereupon be adjusted
accordingly.  Not later than sixty (60) days after the end of each fiscal year
during the Term and after Lease termination, Landlord shall render a statement
("Landlord's Statement") in reasonable detail and according to generally
accepted accounting principles consistently applied certified by Landlord and
showing for the preceding fiscal year or fraction thereof, as the case may be,
the actual Annual Maintenance Charges for the said fiscal year or fraction
thereof, and thereupon any balance owed by Tenant or excess paid by Tenant under
this Section shall be paid to Landlord, or credited to Tenant, as the case may
be, on the next rent payment date.  Landlord shall furnish Tenant with copies of
all reasonable documentation and records for the Annual Maintenance Charges for
any fiscal year upon Tenant's request for the same; provided, however, that
Landlord shall not be required to furnish such copies for any fiscal year if
Tenant has not requested such copies within two (2) years after the expiration
of such fiscal year.

     For purposes of this Lease, the first "fiscal year" shall be the annual
period commencing on the Commencement Date and ending on December 31 of the year
in which the Commencement Date occurs subsequently, the term "fiscal year" shall
mean each consecutive annual period thereafter, commencing on the day following
the end of the preceding fiscal year.  Landlord shall have the right from time
to time to change the periods of accounting under this Section 4.2.4 to any
annual period other than a fiscal year, and upon any such change all items
referred to in this Section shall be appropriately apportioned.  In all
Landlord's Statements rendered under this Section, amounts for periods partially
within and partially without the accounting periods shall be appropriately
apportioned, and any items which are not determinable at the time of a
Landlord's Statement shall be included therein on the basis of Landlord's
estimate, and with respect thereto Landlord shall render promptly after
determination a supplemental Landlord's Statement, and appropriate adjustment
shall be made according thereto.  All of Landlord's Statements shall be prepared
on an accrual basis of accounting.

     Notwithstanding any other provision of this Section 4.2.4, if the Term
expires or is terminated as of a date other than the last day of a fiscal year,
then for such fraction of a fiscal year at the end of the Term, Tenant's last
payment to Landlord under this Section 4.2.4 shall be made on the basis of
Landlord's best reasonable estimate of the items otherwise includable in
Landlord's Statement and shall be made on or before the later of (a) ten (10)
days after Landlord delivers such estimate to Tenant or (b) the last day of the
Term.  Landlord shall thereafter prepare a Landlord's Statement showing the
actual Annual Maintenance Charge for such fiscal year, as hereinabove provided,
and an appropriate payment or refund shall thereafter promptly be made upon
submission of such Landlord's Statement to Tenant.

                                     -17-
<PAGE>

     4.2.5     Payments on Account of Taxes, Insurance and Utilities.

          If required by Landlord after not less than thirty (30) days, advance
notice, Tenant shall make payments on account of the Annual Tax, Insurance and
Utility Charge (as hereinafter defined) monthly in advance on the first day of
each calendar month during the Term.  At the beginning of every fiscal year,
Landlord shall deliver to Tenant its reasonable estimate of the Annual Tax,
Insurance and Utility Charge ("the Estimated Annual Tax, Insurance and Utility
Charge") for said fiscal year, and Tenant shall make payments on account of the
Annual Tax, Insurance and Utility Charge monthly in advance on the first day of
each calendar month during the Term in the amount of one-twelfth of the
Estimated Annual Tax, Insurance and Utility Charge.  Landlord reserves the right
to reasonably re-estimate and modify the Estimated Annual Tax, Insurance and
Utility Charge by notice to Tenant once annually on the Additional Rent
Adjustment Date (as defined in Section 4.2.4 hereof), and Tenant's payments
shall thereupon be adjusted accordingly.

          Not later than sixty (60) days after the end of each fiscal year
during the Term and after Lease termination, Landlord shall render a statement
in reasonable detail and according to generally accepted accounting practices
certified by Landlord and showing for the preceding fiscal year or fraction
thereof, as the case may be, the actual Annual Tax, Insurance and Utility Charge
for the said fiscal year or fraction thereof, and thereupon any balance owed by
Tenant or excess paid by Tenant under this Section shall be paid to Landlord, or
credited to Tenant, as the case may be, on the next rent payment date.  As used
herein, the term "Annual Tax, Insurance and Utility Charge" shall mean and refer
to the amount of funds paid by Tenant pursuant to Section 4.2.1, 4.2.2 and 4.2.3
for the fiscal year in question for costs actually incurred by Landlord (without
any mark-up for Landlord's overhead or profit).  All payments under this Section
shall to the extent thereof relieve Tenant of its obligations under said
Sections 4.2.1, 4.2.2 and 4.2.3 hereof.

          Landlord shall have the right from time to time to change the periods
of accounting under this Section 4.2.5 to any annual period other than a fiscal
year, and upon any such change all items referred to in this Section shall be
appropriately apportioned.  In all Landlord's annual statements rendered under
this Section, amounts for periods partially within and partially without the
accounting periods shall be appropriately apportioned, and any items which are
not determinable at the time of such a statement shall be included therein on
the basis of Landlord's reasonable estimate, and with respect thereto Landlord
shall render promptly after determination a supplemental statement, and an
appropriate adjustment shall be made according thereto.  All of landlord's
statements under this Section shall be prepared on an accrual basis of
accounting.

          Notwithstanding any other provision of this Section 4.2.5, if the Term
expires or is terminated as of a date other than the last day of a fiscal year,
then for such fraction of a fiscal year at the end of the Term, Tenant's last
payment to Landlord under this Section 4.2.5 shall be made on the basis of
Landlord's best reasonable estimate of the items otherwise includable in the
annual statement rendered by Landlord under this Section and shall be made on or
before the later of (a) 10 days after Landlord delivers such estimate to Tenant
or (b) the last day of the Term, with an appropriate payment or refund to be
made upon submission of Landlord's statement.

                                     -18-
<PAGE>

  4.2.6     Equitable Adjustment of Additional Rent.

          Notwithstanding any other provision of this Lease to the contrary, if
the amount charged to Tenant as Additional Rent under Section 4.2 for any
Operating Expense (as hereinafter defined) is based upon the proportion which
the Premises Floor Area bears to the Building Floor Area, and such amount is
more or less than the amount reasonably allocable to Tenant based upon the value
(with respect to ad valorem real estate taxes) or use of the Premises, then such
amount may be equitably adjusted by Landlord to reflect such disproportionality.
As used herein, the term "Operating Expense" shall mean and refer to ad valorem
real estate taxes and betterment assessments, utilities, insurance, the Annual
Lot Maintenance Charge and the Annual Building Maintenance and Operation Charge.

4.3  LATE PAYMENT OF RENT.

     If any installment of rent is paid after the date the same was due, it
shall bear interest from the due date at the prime commercial rate of
BankBoston, as it may be adjusted from time to time, plus 4% per annum, but in
no event more than the highest rate of interest allowed by applicable law. Any
amounts due under this Section 4.3 shall be Additional Rent.

                                   ARTICLE V

                         TENANT'S ADDITIONAL COVENANTS

5.1  AFFIRMATIVE COVENANTS.

     Tenant covenants at its expense at all times during the Term and for such
further time as Tenant occupies the Premises or any part thereof:

  5.1.1     Perform Obligations.

          To perform promptly all of the obligations of Tenant set forth in this
Lease; and to pay when due the Fixed Rent and Additional Rent and all charges,
rates and other sums which by the terms of this Lease are to be paid by Tenant.

  5.1.2     Occupancy and Use.

          Tenant hereby covenants and agrees not to use and occupy the Premises
other than for the Permitted Uses, and to procure all licenses and permits
necessary for the Permitted Uses at Tenant's sole expense. Landlord covenants
and agrees that the Building has a certificate of occupancy which entitles
Tenant to legally occupy the Premises, subject to the foregoing.

          Without limitation, Tenant shall strictly comply with all federal,
state, and municipal laws, ordinances, and regulations governing the use of
Tenant's laboratory, scientific experimentation and the generation, storage,
containment and disposal of medical waste. Tenant shall be solely responsible
'for procuring and complying at all times with any and all permits, approvals
and licenses required under any Federal, state and municipal laws, ordinances
and regulations relating or incident to: the conduct of its office and research
activities in the Premises; its scientific experimentation, transportation,
storage, handling, use and disposal of

                                     -19-
<PAGE>

any Hazardous Materials (as hereinafter defined) including without limitation
all chemical or radioactive or bacteriological or pathological substances or
organisms or other hazardous wastes or environmentally dangerous substances or
materials or medical waste. Within ten (10) days of a request by Landlord, which
request shall be made not more than once during each period of twelve (12)
consecutive months during the Term hereof, unless otherwise requested by any
mortgagee of Landlord, Tenant shall furnish Landlord with copies of all such
permits which Tenant possesses or has obtained together with a certificate
certifying that such permits are all of the permits, approvals and licenses
which Tenant possesses or has obtained with respect to the Premises. Tenant
shall be entitled to redact any Confidential Information from the copies of such
permits and accompanying certificates of Tenant. Tenant shall promptly give
notice to Landlord of any violations and notices of noncompliance relative to
its use and operation of the Premises from any federal, state, or municipal
agency or by any court of law and shall promptly cure the conditions causing any
such violations or noncompliance. Tenant shall not be deemed to be in default of
its obligations under the preceding sentence to promptly notify Landlord or cure
any condition causing any such violation, nor its compliance obligations
generally under this Section 5.1.2 in the event that, in lieu of such cure,
Tenant shall contest the validity of such violation by appellate or other
proceedings permitted under applicable law, provided that: (i) any such contest
is made reasonably and in good faith, (ii) Tenant makes reasonable provisions,
including, without limitation, posting bond(s) or giving other security,
reasonably acceptable to Landlord to protect Landlord, the Building and the Lot
from any liability, costs, damages or expenses arising in connection with such
violation and failure to cure, (iii) Tenant shall agree to indemnify, defend
(with counsel reasonably acceptable to Landlord) and hold Landlord harmless from
and against any and all liability, costs, damages, or expenses arising in
connection with such condition and/or violation, (iv) Tenant shall promptly cure
any violation in the event that its appeal of such violation is overruled or
rejected beyond right of further appeal, and (v) Tenant shall certify to
Landlord's satisfaction that Tenant's decision to delay such cure shall not
result in any actual or threatened bodily injury or property damage to Landlord,
any tenant or occupant of the Building or the Lot, or any other person or
entity. Landlord agrees that any Confidential Information gained or obtained by
Landlord pursuant to this Section 5.1.2 shall be kept confidential in accordance
with Section 10.15 hereof.

     5.1.3     Repair and Maintenance.

          Except as otherwise provided in Article VI, to keep the interior of
the Premises including, without limitation, all fixtures and equipment now or
hereafter on the Premises, or exclusively serving the Premises, but excluding
the exterior (exclusive of glass) and structural elements of the Building and
the grounds and parking lot, which Landlord shall maintain and repair unless
such repairs are required because of Tenant's willful misconduct or negligence,
in good order, condition and repair and at least as good order, condition and
repair as they are in on the Commencement Date or may be put in during the Term,
reasonable use and wear only excepted; to keep in a safe, secure and sanitary
condition all trash and rubbish temporarily stored at the Premises; and to make
all repairs and maintenance and to do all other work necessary for the foregoing
purposes whether the same may be ordinary or extraordinary, foreseen or
unforeseen. Tenant shall secure, pay for and keep in force contracts with
appropriate and reputable service companies providing for the regular
maintenance of the heating and air-conditioning systems serving solely the
Premises and which were installed by Tenant and copies of such contracts shall
be furnished to Landlord; provided, however, that it is agreed that Tenant

                                     -20-
<PAGE>

shall be responsible only for the repair and maintenance of the heating and air-
conditioning systems and the components thereof located within or exclusively
serving the Premises and which were installed by Tenant. It is further agreed
that the exception of reasonable use and wear shall not apply so as to permit
Tenant to keep the Premises in anything less than suitable, tenantlike, and
efficient and usable condition considering the nature of the Premises and the
use reasonably made thereof, or in less than good and tenantlike repair.

  5.1.4     Compliance with Law.

          To make all repairs, alterations, additions or replacements to the
Premises required as a result of Tenant's use of the Premises by any law or
ordinance or any order or regulation of any public authority other than major
capital repairs, alterations, additions or replacements to the foundations and
structural elements of the Building which are not required because of Tenant's
failure to comply with the Provisions of Article 5.1.3 hereof; to keep the
Premises equipped with all safety appliances so required; to pay all municipal,
county, or state taxes assessed against Tenant's the leasehold interest
hereunder, or against personal property of any kind owned by Tenant on or about
the Premises; and to comply with the orders and regulations of all governmental
authorities with respect to zoning, building, fire, health and other codes,
regulations, ordinances or laws applicable to the Premises.

          The Tenant shall not use, generate, manufacture, produce, handle,
store, release, discharge or dispose of in, on, under or about the Premises or
transport to or from the Premises, or allow its employees, agents, contractors,
invitees or any other person or entity to do so, any Hazardous Materials except
to the extent that the following conditions regarding the use, generation,
manufacture, production, handling, storing, releasing, discharging, disposal or
transport (individually or collectively, the "Use") of Hazardous Materials shall
be satisfied: (i) the Use shall be directly related to the operation of Tenant's
business as permitted herein, (ii) Tenant shall provide Landlord with a copy of
any and all notices or lists of the types and quantities of such proposed
hazardous materials used in, on or at the Premises which Tenant is required to
furnish to any Federal, state or municipal governmental agencies or authorities
or any fire insurance underwriters (collectively "Governmental Authorities") for
purposes of compliance with any Environmental Law (as hereinafter defined), and
shall update such list as necessary for continuing accuracy and legal
compliance, and such other information reasonably satisfactory to Landlord as
Landlord may reasonably require concerning such Use, (iii) such Use shall be in
strict compliance (at Tenant's expense) with all applicable laws, regulations,
licenses and permits including without limitation all Environmental Laws, and
(iv) such use shall not invalidate or limit the coverage or increase the
premiums of any insurance policy affecting or covering the Building or the Lot.
Landlord hereby covenants and agrees that the information contained in any list,
or update thereof, referred to in the foregoing clause (ii) shall be kept
confidential in accordance with Section 10.15 hereof. Notwithstanding the
foregoing, Tenant hereby agrees to consult and coordinate with Landlord prior to
transporting any Hazardous Materials to or from the Premises whenever (i) such
transportation is not of the kind regularly made during the ordinary course of
business by a person or entity operating a laboratory or light manufacturing
facility for the Permitted Uses or (ii) Tenant has reason to believe that such
transportation may result in a public demonstration, protest or other similar
disturbance at the Building or the Lot. If the transportation, generation,
manufacture, production, handling, release, storage, use or disposal of any
hazardous materials anywhere on the Premises in connection with

                                     -21-
<PAGE>

the Tenant's use of the Premises results in (1) contamination of the soil,
surface or ground water or any other environmental media or (2) loss or damage
to person(s) or property, then Tenant agrees to respond in accordance with the
following paragraph:

          Tenant agrees (i) to notify Landlord immediately of any
          contamination, claim of contamination, threat of
          contamination, release of Hazardous Materials, threat of
          release of Hazardous Materials, loss or damage, (ii) after
          consultation and approval by Landlord, to clean up the
          contamination in full compliance with all applicable
          statutes, regulations and standards, including without
          limitation all Environmental Laws, and (iii) to indemnify,
          defend (with counsel acceptable to Landlord) and hold
          Landlord harmless from and against any claims, suits,
          causes of action, costs and fees, including attorneys, and
          consultants' fees, arising from or connected with any such
          contamination, claim-of contamination, threat of
          contamination, release of Hazardous Materials, threat of
          release of Hazardous Materials, loss or damage. No consent
          or approval of Landlord shall in any way be construed as
          imposing upon Landlord any liability for the means,
          methods, or manner of removal, containment or other
          compliance with applicable law for and with respect to the
          foregoing.

          Tenant shall promptly notify Landlord upon Tenant's receipt of any
inquiry, notice, or threat to give notice by any government authority or any
other third party with respect to any Hazardous Materials. Notwithstanding the
foregoing, Tenant shall not be liable to Landlord hereunder for any
contamination, claim of contamination, loss or damage arising in connection with
Hazardous Materials to the extent the same is the result of (A) Hazardous
Materials existing in the Building and the Lot prior to Tenant's use or
occupancy of the Premises, (B) migration of Hazardous Materials from any other
site onto the Lot which migration is not caused by Tenant, (C) the generation,
manufacture, production, handling, release, storage, use or disposal of any
Hazardous Materials at the Building or the Lot by Landlord, any other tenant or
occupant, or any so-called "mid-night dumpers" (provided, however, that Tenant
shall be liable for events described in this section (C) where Tenant's agents,
employees, contractors, invitees, assignees or sublessees shall have caused or
contributed to the same), or (D) the Use (as defined above in this Section) by
any party other than Tenant of Hazardous Materials at the Building or the Lot
after the date upon which Tenant has completely vacated the same, including
removal of all of its property (to the extent permitted herein) and Hazardous
Materials. Tenant's indemnification obligations under this Section shall survive
the expiration or earlier termination of this lease.

     The term "Hazardous Materials" as used herein shall mean and include any
and all material(s) or substance(s) defined or treated in any federal, state, or
local law, statute, regulation, ordinance, order, by-law, code, requirement, or
directive, including without limitation the Comprehensive Environmental
Response, Compensation, and Liability Act, 42 U.S.C. Section 9601, et seq., as
                                                                   -- ---
amended ("CERCLA")(and its implementing regulations), the Resource Conservation
and Recovery Act of 1976, 42 U.S.C. Section 6901, et seq., as amended PIRCRAII)
                                                  -- ---
(and its implementing regulations), the Massachusetts Oil and Hazardous
Material

                                     -22-
<PAGE>

Release Prevention and Response Act, M.G.L. c. 21E (and its implementing
regulations), and the Massachusetts Hazardous Waste Management Act, M.G.L. c.
21C (and its implementing regulations), as posing potential risk to persons,
property, public health, safety, or welfare or the environment or dangerous,
toxic or hazardous, including without limitation any and all pollutants,
contaminants, chemicals, wastes, lead paint, urea formaldehyde, polychlorinated
biphenyls, asbestos, radioactive materials, explosives, carcinogens,
bacteriological or pathological substances or organisms, oil, petroleum,
petroleum products and any and all other wastes, materials, and substances which
could lead to any liability, costs, damages, and/or penalties under any
Environmental Laws.

     "Environmental Law(s)" as used herein shall mean any environmental, health
and safety-related law, statute, regulation, rule, ordinance, by-law, license,
permit, action, policy or authorization relating in any manner to Hazardous
Materials or the existence, use, discharge, release, containment,
transportation, or disposal thereof, at the federal, state, or local level, and
any judicial or administrative or regulatory decree, judgment or order, whether
existing as of the date hereof, previously enforced, or subsequently enacted.

          Nothing herein contained shall be construed to limit or impair
Tenant's obligation to comply with any law, code, rule or regulation which
requires Tenant to notify any Governmental Authority or any other person
concerning the Use (as defined above in this Section) of Hazardous Materials by
Tenant at the Premises.

          Tenant agrees that, with respect to the Premises, it shall be
responsible for compliance with the Americans with Disabilities Act (42 U.S.C.
(S) 12101 et seq.) and the regulations and Accessibility Guidelines for
          -- ---
Buildings and Facilities issued pursuant thereto (collectively, the "ADA
Requirements").  Landlord agrees that otherwise Landlord is responsible for
compliance under the ADA Requirements.

          Tenant covenants and agrees that its use of the Premises shall not
cause a discharge of more than its pro rata share on a square foot basis of the
design flow gallonage per day of sanitary (non-industrial) sewage allowed under
the sewage discharge permit(s) for the Building.  Discharges in excess of that
amount, and any discharge of industrial sewage, shall only be permitted if
Tenant, at its sole expense, shall have obtained all necessary permits and
licenses therefor, including without limitation permits from state and local
authorities having jurisdiction thereof.

  5.1.5     Tenant's Work.

          To procure at Tenant's sole expense all necessary permits and licenses
before undertaking any work on the Premises; to do all such work in compliance
with the applicable provisions of Sections 3.3 and 5.2.3 hereof; to do all such
work in a good and workmanlike manner employing materials of good quality and so
as to conform with all applicable zoning, environmental, building, fire, health
and other codes, regulations, ordinances and laws and the ADA Requirements; to
keep the Premises at all times free of liens for labor and materials; to employ
for such work one or more responsible contractors whose labor will work without
interference with other labor working on the Premises; to require such
contractors employed by Tenant to carry worker's compensation insurance in
accordance with statutory requirements and

                                     -23-
<PAGE>

comprehensive public liability insurance covering any general contractors on or
about the Premises in amounts required under Section 3.5 and to submit
certificates evidencing such coverage to Landlord prior to the commencement of
such work; and to save Landlord harmless and indemnified from all injury, loss,
claims or damage to any person or property occasioned by or growing out of such
work. Notwithstanding any other provision of this Section 5.1.5 or any other
provision of this Lease to the contrary, Landlord shall not, subject to
applicable law, prohibit Tenant from using non-union labor to perform any work
at the Premises. Without limitation of the foregoing, Landlord shall not require
Tenant's employees to unionize.

  5.1.6     Indemnity.

          To defend, with counsel reasonably approved by Landlord, all actions
against Landlord, any partner, trustee, stockholder, officer, director, employee
or beneficiary of Landlord, holders of mortgages secured by the Premises or the
Building and Lot and any other party having an interest in the Premises
("Indemnified Parties") with respect to, and to pay, protect, indemnify and save
harmless, to the extent permitted by law, all Indemnified Parties from and
against, any and all liabilities, losses, damages, costs, expenses (including
reasonable attorneys' fees and expenses), causes of action, suits, claims,
demands or judgments of any nature arising from (i) injury to or death of any
person, or damage to or loss of property, on the Premises or on adjoining
sidewalks, streets or ways connected with the use or occupancy thereof by Tenant
or its agents, contractors, licensees, employees, or sublessees, unless and to
the extent caused by the negligence or willful misconduct of Landlord or its
servants or agents, or (ii) any negligence, or willful misconduct of Tenant or
its agents, contractors, licensees, employees, or sublessees.

  5.1.7     Landlord's Right to Enter.

          Subject to the provisions of Section 2.1 to permit Landlord and its
agents to enter into the Premises at reasonable times and upon reasonable
advance notice (except in case of emergency in which event no prior notice shall
be required but notice shall be given as soon as reasonably practicable) to
examine the Premises, make such repairs and replacements as Landlord may elect,
without however, any obligation to do so except as may be otherwise expressly
set forth in this Lease, and show the Premises to prospective purchasers and
lenders, and, during the last twelve months of the Term, to show the Premises to
prospective tenants. Landlord's right to enter the Premises in accordance with
the foregoing shall be subject to Landlord's obligations pursuant to Section
10.14 hereof and Landlords obligation not to unreasonably disrupt Tenant's
conduct of its business. Notwithstanding the foregoing, Landlord agrees that in
the event that Landlord shows the Premises to any prospective purchaser or
tenant, Landlord shall: (i) provide at least three (3) days' notice to Tenant
identifying the prospective purchaser or tenant, and (ii) only show the Premises
to such purchaser or tenant if Landlord believes in good faith that such person
or entity is a bona fide prospective purchaser or tenant. In all cases Landlord
shall conduct such showings in compliance with such reasonable requests and
instructions as Tenant may make for purposes of protecting Tenant's Confidential
Information.

                                     -24-
<PAGE>

  5.1.8     Personal Property at Tenant's Risk.

          All of the furnishings, fixtures, equipment, effects and property of
every kind, nature and description owned or leased by Tenant or by any person
claiming by, through or under Tenant which, during the continuance of this Lease
or any occupancy of the Premises by Tenant or anyone claiming under Tenant, may
be on the Premises, shall, as between the parties, be at the sole risk and
hazard of Tenant and if the whole or any part thereof shall be destroyed or
damaged by fire, water or otherwise, or by the leakage or bursting of water
pipes, steam pipes, or other pipes, by theft or from any other cause, no part of
said loss or damage is to be charged to or to be borne by Landlord, except that
Landlord shall in no event be indemnified or held harmless or exonerated from
any liability to Tenant or to any other person, for any injury, loss, damage or
liability to the extent such injury, loss, damage or liability is the result of
the negligence or willful misconduct of Landlord, its contractors, agents or
employees, or (ii) such indemnification, agreement to hold harmless or
exoneration is prohibited by law.

  5.1.9     Payment of Landlord's Cost of Enforcement.

          To pay on demand Landlord's expenses, including reasonable attorney's
fees, incurred in enforcing any obligation of Tenant under this Lease or in
curing any default by Tenant under this Lease as provided in Section 7.4.

  5.1.10    Yield Up.

          Subject to Section 3.3 hereof, at the expiration of the Term or
earlier termination of this Lease: to surrender all keys to the Premises; to
remove all of its trade fixtures and personal property in the Premises; to
remove such installations and improvements made by Tenant as Landlord may
require as a condition to Landlord's approval of alterations in accordance with
Section 3.5 and all Tenant's signs wherever located; to repair all damage caused
by such removal; and to otherwise yield up the Premises, broom-clean and in the
same good order and repair in which Tenant is obliged to keep and maintain the
Premises by the provisions of this Lease. Subject to Section 3.4 hereof, any
property not so removed shall be deemed abandoned and may be removed and
disposed of by Landlord in such manner as Landlord shall determine and Tenant
shall pay Landlord the entire reasonable cost and expense incurred by Landlord
in effecting such removal and disposition and in making any incidental repairs
and replacements to the Premises and for use and occupancy during the period
after the expiration of the Term and prior to Tenant's performance of its
obligations under this Section 5.1.10. Tenant shall further indemnify Landlord
against all loss, cost and damage resulting from Tenant's failure and delay in
surrendering the Premises as above provided.

  5.1.11    Estoppel Certificate.

          Upon not less than ten (10) days' prior notice by Landlord, to
execute, acknowledge and deliver to Landlord a statement in writing certifying
that this Lease is unmodified and in full force and effect and that except as
stated therein Tenant has no knowledge of any defenses, offsets or counterclaims
against its obligations to pay the Fixed Rent and Additional Rent and any other
charges and to perform its other covenants under this Lease (or, if there have
been any modifications that the Lease is in full force and effect as modified
and

                                     -25-
<PAGE>

stating the modifications and, if there are any defenses, offsets or
counterclaims, setting them forth in reasonable detail), the dates to which the
Fixed Rent and Additional Rent and other charges have been paid and a statement
that, to the best of Tenant's knowledge, Landlord is not in default hereunder
(or if in default, the nature of such default, in reasonable detail) and such
other matters reasonably required by Landlord or any prospective purchaser or
mortgagee of the Premises. Any such statement delivered pursuant to this Section
5.1.11 may be relied upon by any prospective purchaser or mortgagee of the
Premises, or any prospective assignee of any such mortgage.

  5.1.12    Landlord's Expenses Re Consents.

          To reimburse Landlord promptly on demand for all reasonable legal
expenses incurred by Landlord in connection with all requests by Tenant for
consent or approval under this Lease.

  5.1.13    Rules and Regulations.

          To comply with the Rules and Regulations set forth in Exhibit C, as
                                                                ---------
the same may be amended from time to time by Landlord to provide for the
beneficial operation of the Building and/or Lot, provided that such amendments
do not materially interfere with Tenant's right of use and enjoyment of the
Premises pursuant to this Lease, it being understood that, subject to the
provisions of Section 10.2 hereof, Landlord shall not be liable to Tenant for
the failure of other tenants of the Building or the Lot to conform to such Rules
and Regulations but Landlord shall enforce such rules and regulations in a non-
discriminating manner.

  5.1.14    Loading.

          Not to place Tenant's Property, as defined in Section 5.1.8, upon the
Premises so as to exceed the floor load limits set forth in Exhibit D attached
                                                            ---------
hereto and not to move any safe, vault or other heavy equipment in, about or out
of the Premises except in such manner and at such times as Landlord shall in
each instance reasonably approve; Tenant's business machines and mechanical
equipment which cause vibration or noise that may be transmitted to the Building
structure or to any other leased space in the Building shall be placed or
maintained by Tenant in settings of cork, rubber, spring, or other types of
vibration eliminators sufficient to reduce such vibration or noise to a level
reasonably acceptable to Landlord.

  5.1.15    Holdover.

          To pay to Landlord (i) the greater of twice (a) the then fair market
rent as reasonably determined by Landlord or (b) the total of the Fixed Rent,
Additional Rent, and all other payments then payable hereunder, for each month
or portion thereof Tenant shall retain possession of the Premises or any part
thereof after the termination of this Lease, whether by lapse of time or
otherwise, and (ii) all damages sustained by Landlord on account thereof;
provided, however, that any payments made by Tenant under the foregoing clause
(i) in excess of the then fair market rent for the Premises as so reasonably
determined by Landlord shall be applied against any damages under the foregoing
clause (ii).  The provisions of this subsection shall not operate as a waiver by
Landlord of the right of re-entry provided in this Lease.

                                     -26-
<PAGE>

5.2  NEGATIVE COVENANTS.

     Tenant covenants at all times during the Term and for such further time as
Tenant occupies the Premises or any part thereof:

     5.2.1     Assignment and Subletting; Mortgaging.

          Not without the prior written consent of Landlord to assign this
Lease, to make any sublease, or to permit occupancy of the Premises or any part
thereof by anyone other than Tenant, voluntarily or by operation of law, except
as hereinafter provided; as Additional Rent, to reimburse Landlord promptly for
reasonable legal and other expenses incurred by Landlord in connection with any
request by Tenant for consent to assignment or subletting (subject to the
provisions of Section 5.1.12 hereof); no assignment or subletting shall affect
the continuing primary liability of Tenant (which, following assignment, shall
be joint and several with the assignee); no consent to any of the foregoing in a
specific instance shall operate as a waiver in any subsequent instance. No
sublessee, assignee or mortgagee succeeding to Tenant's interest under the Lease
shall be permitted to use the Premises other than for the Permitted Uses.
Landlord's consent shall be required as to the reasonable creditworthiness of
any proposed assignee in view of market conditions then prevailing for leases
having terms and conditions comparable to this Lease. Landlord's consent to any
assignment or subletting by Tenant shall not be unreasonably withheld, provided
that Tenant is not then in default beyond applicable notice and grace periods
under this Lease and that such assignee or subtenant pays therefor the greater
of the Fixed Rent, Additional Rent, and all other payments then payable
hereunder, or the then fair market rent for the Premises. If Tenant requests
Landlord's consent to assign this Lease, or to sublet any portion of the
Premises such that Tenant shall not occupy at least fifty percent (50%) of the
rentable square footage of the Premises after the date of commencement of such
sublease, Landlord shall have the option, exercisable by written notice to
Tenant given within 10 days after receipt of such request, to terminate this
Lease as of the date of commencement the proposed sublease or assignment;
provided, however, that Tenant shall have the right to rescind any such request
in the event Landlord elects to so terminate this Lease by notice given to
Landlord within five (5) days after the date of such termination notice from
Landlord, in which event such termination notice shall be of no further force or
effect;

          Notwithstanding the foregoing provisions of this Section 5.2.1, Tenant
may assign this Lease or sublet any portion of the Premises without Landlord's
consent to (i) any successor of Tenant resulting from a merger or consolidation
of Tenant and (ii) any Affiliate of Tenant (as hereinafter defined) whose net
worth is equal to or greater than the net worth of Tenant as of the date hereof,
provided that Tenant provides Landlord at least forty-five (45) days prior
notice of such assignment or subletting pursuant to the foregoing clause (ii).
As used herein, the term "Affiliate of Tenant" shall mean and refer to any
entity controlled by, controlling or under common control with Tenant.

          In the event that any assignee or subtenant of Tenant pays to Tenant
any amount in excess of the Fixed Rent, Additional Rent, and all other payments
then payable hereunder (excluding any payments on account of goods or services
being provided, furnished or conveyed by Tenant not otherwise provided by
Landlord), or pro rata portion thereof on a square footage basis for any portion
of the Premises (such excess being hereinafter referred to as "Sublease

                                     -27-
<PAGE>

Profits"), Tenant shall promptly pay fifty percent (50%) of said Sublease
Profits to Landlord as and when received by Tenant after deduction of Tenant's
Sublease Costs (as hereinafter defined) The term "Sublease Costs" shall mean and
refer to Tenant's reasonable legal, brokerage and construction costs and
expenses, and any other reasonable and customary costs associated with the
assignment or sublease transaction, incurred in good faith in view of the size
and expected term of any applicable sublease or assignment. Sublease Costs shall
be amortized over the term of the applicable sublease or assignment.

          Notwithstanding anything to the contrary provided in this Section
5.2.1, Tenant may mortgage, pledge, hypothecate, collaterally assign or
otherwise offer its interest under this Lease as security for a loan for the
construction of its Leasehold Improvements ("mortgage the leasehold interest of
Tenant"), which loan secured by a mortgage of leasehold interest of Tenant shall
only include the financing of Leasehold Improvements which become real estate
----
fixtures to the Building and the Premises and shall not include Tenant's trade
fixtures, equipment or other movable items, in which event:

               (a)  Landlord shall furnish Tenant and the secured party under
          its mortgage of the leasehold interest of Tenant a formal consent,
          estoppel and agreement with respect to this Lease, in form and
          substance reasonably satisfactory to Landlord, wherein Landlord shall
          agree as more particularly set forth in such agreement, among other
          things, that (i) notices of default must be given simultaneously to
          the secured party with their being given to Tenant in order for such a
          notice to be properly given, and (ii) the secured party shall have the
          right to cure any default by Tenant which, except for monetary
          defaults, shall include an additional cure period of ten (10) days for
          the secured party extending beyond Tenant's cure period.

               (b) Any assignment or subletting by the secured party or anyone
          deriving their interest in this Lease under such secured party
          ("Successor Tenant") shall be subject to Landlord's reasonable
          approval under the same circumstances as if Tenant continued to hold
          the Tenant's interest under this Lease.

               (c) The secured party shall be required to give simultaneous
          notice to Landlord of Tenant's default under the mortgage of Tenant's
          leasehold interest.

               (d) The secured party shall be required to pay all then unpaid
          and due and payable Fixed Rent and Additional Rent due Landlord under
          the Lease upon entering the Premises in order to exercise its remedies
          for default by Tenant.

               (e) Prior to the foreclosure by secured party of the mortgage of
          leasehold interest of Tenant, the secured party shall offer Landlord,
          and Landlord shall have the option, but shall not be obligated, to pay
          to the secured party the then outstanding balance due the secured
          party under the loan secured by the mortgage of leasehold interest of
          Tenant referred to above. If Landlord accepts the secured party's
          offer within ten (10) days, and pays the secured party the outstanding
          balance as aforesaid within such ten (10) day period, secured party
          shall have no right to possession of the Premises and the mortgage of
          the

                                     -28-
<PAGE>

          leasehold interest of Tenant shall be discharged, and such payment by
          Landlord to the secured party shall be deemed an Event of Default
          under the Lease whereby Tenant shall be required to relinquish the
          Premises to Landlord.

               (f)  Upon foreclosure of Tenant's leasehold interest Successor
          Tenant may exercise whatever rights Tenant has under this Lease to
          sublet or assign Tenant's interest under this Lease as Tenant, subject
          to the provisions of this Section 5.2.1, provided that one hundred
          percent (100%) of any amounts paid to Successor Tenant by a subtenant
          in excess of the Fixed Rent, Additional Rent, and all other payments
          then payable hereunder (excluding any payments on account of goods or
          services being provided, furnished or conveyed by Successor Tenant not
          otherwise provided by Landlord), or pro rata portion thereof on a
          square footage basis for any portion of the Premises (such excess
          being hereinafter referred to as "Successor Tenant Sublease Profits"),
          shall be promptly paid to Landlord as and when received by Successor
          Tenant after deduction of Successor Tenant's Sublease Costs (as
          hereinafter defined). The term "Successor Tenant's Sublease Costs"
          shall mean and refer to the reasonable legal, brokerage and
          construction costs and expenses associated with the sublease
          transaction, the outstanding balance due the secured party under the
          loan secured by the mortgage of the leasehold interest of Tenant and
          any other reasonable and customary costs associated with the
          foreclosure of the aforesaid mortgage, incurred in good faith in view
          of the size and expected term of any applicable sublease. Sublease
          Costs shall be amortized over the term of the applicable sublease or
          assignment. Any amounts paid by Successor Tenant to the secured party
          for assignment of the Lease shall first be applied against the
          outstanding balance due the secured party under the loan secured by
          the mortgage of the leasehold interest of Tenant and otherwise such
          amount shall be exclusively payable to Landlord. Nothing set forth
          herein shall affect or impair the liability of Tenant, any secured
          party foreclosing the mortgage of leasehold interest of Tenant, or any
          Successor Tenant to pay to Landlord all Fixed Rent, Additional Rent
          and other sums due Landlord pursuant to this Lease.

                    Notwithstanding the foregoing, subsequent to the
          foreclosure, and upon subletting the Premises as provided herein,
          Landlord shall be entitled to require that at least one (1) sublease
          shall demise at least fifty percent (50%) of the floor area of the
          Premises.

  5.2.2     Nuisance.

          Not to injure, deface or otherwise harm the Premises; nor commit any
nuisance; nor permit the emission of any noise, vibration or odor which is
contrary to any law or ordinance; nor make, allow or suffer any waste; nor make
any use of the Premises which is improper, offensive or contrary to any law or
ordinance or which will invalidate any of Landlord's insurance.

                                     -29-
<PAGE>

                                   ARTICLE VI

                               CASUALTY OR TAKING

6.1  TERMINATION.

     In case during the period which is twelve (12) or fewer months prior to the
expiration of the Term all or any substantial part of the Premises or of the
Building or of the Lot or any one or more of them shall be taken by any public
authority or for any public use, or shall be destroyed or damaged by fire or
casualty, or by the action of any public authority, or Landlord receives
compensable damage by reason of anything lawfully done in pursuance of public or
other authority, (hereinafter referred to as the "Casualty or Taking"), then
this Lease may be terminated at the election of Landlord. Such election, which
may be made notwithstanding the fact that Landlord's entire interest may have
been divested, shall be made by the giving of notice by Landlord to Tenant
within thirty (30) days after the Casualty or Taking.

6.2  RESTORATION.

     Unless this Lease is terminated under Section 6.1, this Lease shall
continue in force notwithstanding any Casualty or Taking and a just proportion
of the rent reserved, according to the nature and extent of the damages
sustained by the Premises, but not in excess of an equitable proportion of the
net proceeds of insurance recovered by Landlord under the rental insurance
coverage carried pursuant to Section 4.2.2.2, shall be abated from the date of
the Casualty or Taking until the Premises, or what may remain thereof, shall be
put by Landlord in proper condition for use subject to zoning and building laws
or ordinances then in existence, which Landlord covenants to do with reasonable
diligence at Landlord's expense, provided that Landlord's obligations with
respect to restoration shall not require Landlord to expend more than the net
proceeds of insurance recovered or damages awarded for such Casualty or Taking.
"Net proceeds of insurance recovered or damages awarded" refers to the gross
amount of such insurance or damages less the reasonable expenses of Landlord in
connection with the collection of the same, including without limitation, fees
and expenses for legal and appraisal services.

     In the case of any Casualty or Taking occurring prior to the last twelve
(12) months prior to expiration of the Term, in the event that all or a
substantial part of the Premises or the Building shall be taken or destroyed as
aforesaid either party's architect reasonably determines that the Premises will
not be reasonably repaired or restored (to the extent permitted by the net
proceeds of insurance recovered or damages awarded from such Casualty or Taking)
within one year after the occurrence of such Casualty or Taking then either
party shall have the right to terminate this Lease by notice given within thirty
(30) days after the date of such determination.

     In the case of a taking, there shall be an equitable permanent adjustment
of Fixed Rent and Additional Rent.

6.3  AWARD.

     Irrespective of the form in which recovery may be had by law, all rights to
damages or compensation shall belong to Landlord in all cases except as set
forth below in this Section 6.3. Tenant hereby grants to Landlord all of
Tenant's rights to such damages and compensation and

                                     -30-
<PAGE>

covenants to deliver such further assignments thereof as Landlord may from time
to time request. It is agreed and understood, however, that Landlord does not
reserve to itself, and Tenant does not assign to Landlord, any damages payable
for (i) Leasehold Improvements (paid for by Tenant), movable trade fixtures
installed by Tenant or anybody claiming under Tenant, at its own cost and
expense or (ii) relocation expenses or damages for loss of business (in excess
of any such damages attributable to the value of this lease) recoverable by
Tenant from such authority.

                                  ARTICLE VII

                                   DEFAULTS

7.1  EVENTS OF DEFAULT.

     (a)  If Tenant shall default in the performance of any of its obligations
to pay the Fixed Rent or Additional Rent hereunder and if such default shall
continue for five (5) days after notice from Landlord to Tenant specifying the
default (provided, however, that Landlord shall not be required to provide such
notice more than two (2) times in any period of twelve (12) consecutive calendar
months) or if within twenty (20) days after default notice from Landlord to
Tenant specifying any other default or defaults Tenant has not commenced
diligently to correct the default or defaults so specified or has not thereafter
diligently pursued such correction to completion, or (b) if any assignment for
the benefit of creditors shall be made by Tenant, or by any guarantor of Tenant,
or (c) if Tenant's leasehold interest shall be taken on execution or other
process of law in any action against Tenant, or (d) if a mechanic's lien or
other involuntary encumbrance is filed against Tenant's leasehold interest, and
is not discharged or bonded over within thirty (30) days after notice to Tenant
of the existence thereof, or (e) if a petition is filed by Tenant or any
guarantor of Tenant for liquidation, or for reorganization or an arrangement or
any other relief under any provision of the Bankruptcy Code as then in force and
effect, or (f) if an involuntary petition under any of the provisions of said
Bankruptcy Code is filed against Tenant or any guarantor of Tenant and such
involuntary petition is not dismissed within thirty (30) days thereafter, or (g)
if Tenant fails to maintain the insurance required under Section 4.2.2.1 hereof,
then, and in any of such cases, Landlord and the agents and servants of Landlord
lawfully may, in addition to and not in derogation of any remedies for any
preceding breach of covenant, immediately or at any time thereafter and without
demand or notice, at Landlord's election, do any one or more of the following:
(1) give Tenant written notice stating that the Lease is terminated, effective
upon the giving of such notice or upon a date stated in such notice, as Landlord
may elect, in which event the Lease shall be irrevocably extinguished and
terminated as stated in such notice without any further action, or (2) with or
without process of law, in a lawful manner and without illegal force, enter and
repossess the Premises as of Landlord's former estate, and expel Tenant and
those claiming through or under Tenant, and remove its and their effects,
without being guilty of trespass, in which event the Lease shall be irrevocably
extinguished and terminated at the time of such entry, or (3) pursue any other
rights or remedies permitted by law. Any such termination of the Lease shall be
without prejudice to any remedies which might otherwise be used for arrears of
rent or prior breach of covenant, and in the event of such termination Tenant
shall remain liable under this Lease as hereinafter provided. Tenant hereby
waives all statutory rights of redemption and Landlord, without notice to
Tenant, may store Tenant's effects, and those of any person claiming through or
under Tenant, at the expense and risk of Tenant, and, if Landlord so elects, may
sell such effects at public

                                     -31-
<PAGE>

auction or private sale and apply the net proceeds to the payment of all sums
due to Landlord from Tenant, if any, and pay over the balance, if any, to
Tenant.

7.2  REMEDIES.

     In the event that this Lease is terminated under any of the provisions
contained in Section 7.1 or shall be otherwise terminated for breach of any
obligation of Tenant, Tenant covenants to pay forthwith to Landlord, as
compensation, the excess, if any, of the total rent reserved for the residue of
the Term over the fair market rental value of the Premises for said residue of
the Term. In calculating the rent reserved there shall be included, in addition
to the Fixed Rent and Additional Rent, the value of all other considerations
agreed to be paid or performed by Tenant during said residue. Tenant further
covenants (as additional and cumulative obligations) after any such termination
to pay punctually to Landlord all the sums and to perform all the obligations
which Tenant covenants in this Lease to pay and to perform in the same manner
and to the same extent and at the same time as if this Lease had not been
terminated. In calculating the amounts to be paid by Tenant pursuant to the next
preceding sentence Tenant shall be credited with any amount paid to Landlord as
compensation as in this Section 7.2 provided and also with the net proceeds of
any rent obtained by Landlord by reletting the Premises, which Landlord shall
exercise reasonable efforts so to do, after deducting all of the Landlord's
reasonable expenses in connection with such reletting, including, without
limitation, all repossession costs, brokerage commissions, fees for legal
services and expenses of preparing the Premises for such reletting, it being
agreed by Tenant that Landlord may (i) relet the Premises or any part or parts
thereof, for a term or terms which may at Landlord's option be equal to or less
than or exceed the period which would otherwise have constituted the balance of
the Term and may grant such concessions and free rent as Landlord in its
reasonable judgment considers advisable or necessary to relet the same and (ii)
make such alterations, repairs and decorations in the Premises as Landlord in
its reasonable judgment considers advisable or necessary to relet the same, and
no action of Landlord in accordance with the foregoing or failure
notwithstanding reasonable efforts having been exercised to relet or to collect
rent under reletting shall operate or be construed to release or reduce Tenant's
liability as aforesaid.

     In lieu of any other damages or indemnity and in lieu of full recovery by
Landlord of all sums payable under all the foregoing provisions of this Section
7.2, Landlord may by notice to Tenant, at any time after this Lease is
terminated under any of the provisions contained in Section 7.1 or is otherwise
terminated for breach of any obligation of Tenant and before such full recovery,
elect to recover, and Tenant shall thereupon pay, as liquidated damages, an
amount equal to the aggregate of the Fixed Rent and Additional Rent accrued in
the twenty-four (24) months ended next prior to such termination, plus the
amount of rent of any kind accrued and unpaid at the time of termination and
less the amount of any recovery by Landlord under the foregoing provisions of
this Section 7.2 up to the time of payment of such liquidated damages.

     Nothing contained in this Lease shall, however, limit or prejudice the
right of Landlord to prove for and obtain in proceedings for bankruptcy or
insolvency by reason of the termination of this Lease, an amount equal to the
maximum allowed by any statute or rule of law in effect at the time when, and
governing the proceedings in which, the damages are to be proved, whether or not
the amount be greater than, equal to, or less than the amount of the loss or
damages referred to above.

                                     -32-
<PAGE>

7.3  REMEDIES CUMULATIVE.

     Any and all rights and remedies which either Landlord or Tenant may have
under this Lease, and at law and equity, shall be cumulative and shall not be
deemed inconsistent with each other, and any two or more of all such rights and
remedies may be exercised at the same time insofar as permitted by law.

7.4  LANDLORD'S RIGHT TO CURE DEFAULTS.

     Landlord may, but shall not be obligated to, cure, at any time, following
the expiration of notice and cure period specified in Section 7.1, ten (10)
days' prior notice to Tenant, except in cases of emergency when no notice shall
be required, any default by Tenant under this Lease; and whenever Landlord so
elects, all costs and expenses incurred by Landlord, including reasonable
attorneys' fees, in curing a default shall be paid by Tenant to Landlord as
Additional Rent on demand, together with interest thereon at the rate provided
in Section 4.3 from the date of payment by Landlord to the date of payment by
Tenant.

7.5  EFFECT OF WAIVERS OF DEFAULT.

     Any consent or permission by Landlord or Tenant to any act or omission by
the other party which otherwise would be a breach of any covenant or condition
herein, or any waiver by Landlord or Tenant of the breach of any covenant or
condition herein by the other party, shall not in any way be held or construed
(unless expressly so declared) to operate so as to impair the continuing
obligation of any covenant or condition herein, or otherwise, except as to the
specific instance, operate to permit similar acts or omissions.

     The failure of Landlord or Tenant to seek redress for violation of, or to
insist upon the strict performance of, any covenant or condition of this Lease
by the other party shall not be deemed a waiver of such violation nor prevent a
subsequent act, which would have originally constituted a violation, from having
all the force and effect of an original violation. The receipt by Landlord, or
the payment by Tenant, as the case may be, of rent with knowledge of the breach
of any covenant of this Lease shall not be deemed to have been a waiver of such
breach by Landlord or Tenant, as the case may be. No consent or waiver, express
or implied, by Landlord or Tenant, as the case may be, to or of any breach of
any agreement or duty shall be construed as a waiver or consent to or of any
other breach of the same or any other agreement or duty.

7.6  NO ACCORD AND SATISFACTION.

     No acceptance by Landlord of a lesser sum than the Fixed Rent, Additional
Rent or any other charge then due shall be deemed to be other than on account of
the earliest installment of such rent or charge due, unless Landlord elects by
notice to Tenant to credit such sum against the most recent installment due, nor
shall any endorsement or statement on any check or any letter accompanying any
check or payment as rent or other charge be deemed an accord and satisfaction,
and Landlord may accept such check or payment without prejudice to Landlord's
right to recover the balance of such installment or pursue any other remedy in
this Lease provided.

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<PAGE>

                                 ARTICLE VIII

                                   MORTGAGES

8.1  RIGHTS OF MORTGAGE HOLDERS.

     The word "mortgage" as used herein includes mortgages, deeds of trust or
other similar instruments evidencing other voluntary liens or encumbrances, and
modifications, consolidations, extensions, renewals, replacements and
substitutes thereof. The word "holder" shall mean a mortgagee, and any
subsequent holder or holders of a mortgage. Until the holder of a mortgage shall
enter and take possession of the Building for the purpose of foreclosure, such
holder shall have only such rights of Landlord as are necessary to preserve the
integrity of this Lease as security. Upon entry and taking possession of the
Building for the purpose of foreclosure, such holder shall have all the rights
and obligation of Landlord. Notwithstanding any other provision of this Lease to
the contrary, including without limitation Section 10.5, no such holder of a
mortgage shall be liable either as mortgagee or as assignee to perform, or be
liable in damages for failure to perform, any of the obligations of Landlord
unless and until such holder shall enter and take possession of the Building for
the purpose of foreclosure, Upon entry for the purpose of foreclosure, such
holder shall be liable to perform all of the obligations of Landlord subject to
and with the benefit of the provisions of Section 10.5, provided that a
discontinuance of any foreclosure proceeding shall be deemed a conveyance under
said provisions to the owner of the equity of the Premises. Except as provided
in Section 4.1(d), no Fixed Rent, Additional Rent or any other charge shall be
paid more than one (1) month in advance of the due dates thereof and payments
made in violation of this provision shall (except to the extent that such
payments are actually received by a mortgagee in possession or in the process of
foreclosing its mortgage) be a nullity as against such mortgagee and Tenant
shall be liable for the amount of such payments to such mortgagee.

     The covenants and agreements contained in this Lease with respect to the
rights, powers and benefits of a holder of a mortgage (including, without
limitation, the covenants and agreements contained in this Section 8.1)
constitute a continuing offer to any person, corporation or other entity, which
by accepting a mortgage subject to this Lease, assumes the obligations herein
set forth with respect to such holder; such holder is hereby constituted a party
of this Lease as an obligee hereunder to the same extent as though its name were
written hereon as such; and such holder shall be entitled to enforce such
provisions in its own name. Tenant agrees on request of Landlord to execute and
deliver from time to time any agreement which may be necessary to implement the
provisions of this Section 8.1.

8.2  PRIORITY OF LEASE; SUBORDINATION.

     This Lease shall be subject to and subordinate to any future mortgage or
other voluntary lien or other encumbrance on the Building or Lot of which the
Premises are a part; provided, however, that Landlord obtains from the holder of
record of any existing or future mortgage an agreement with Tenant by the terms
of which such holder will agree (a) to recognize the rights of Tenant under this
Lease, (b) to perform Landlord's obligations hereunder arising after the date of
such holder's acquisition of title as hereinafter described, expressly
excluding, however, Landlord's obligations under Article III (if any) of this
Lease, and (c) to accept Tenant as tenant

                                     -34-
<PAGE>

of the Premises under the terms and conditions of this Lease in the event of
acquisition of title by such holder through foreclosure proceedings or
otherwise, provided that Tenant will agree to recognize the holder of such
mortgage as Landlord in such event, which agreement shall be made expressly to
bind and inure to the benefit of the successors and assigns of Tenant and of the
holder and upon anyone purchasing said Premises at any foreclosure sale. Tenant
and Landlord agree to execute and deliver any appropriate instruments necessary
to carry out the agreements contained in this Section 8.2. Any such mortgage to
which this Lease shall subordinate may contain such terms, provisions and
conditions as the holder deems usual or customary, provided that such terms and
conditions do not adversely impact Tenant's rights and privileges under this
Lease.

8.3  LEASE AMENDMENTS.

     Provided that Landlord pays all of Tenant's reasonable legal and other
costs associated herewith, Tenant agrees to make such changes in this Lease as
may be reasonably required by the holder of any mortgage of which the Premises
are a part, or any institution which may purchase all or a substantial part of
Landlord's interest in the Premises, provided that such changes may not increase
the Fixed Rent or other payments due hereunder or otherwise materially affect
the obligations of Tenant hereunder, and provided further that such changes do
not, without limitation of the foregoing (i) materially interfere with Tenant's
right of use and enjoyment of the Premises pursuant to this Lease, (ii) limit,
impair or delay Tenant's rights to sublease or assign all or any portion of this
Lease pursuant to Section 5.2.1 hereof, (iii) limit, impair or delay Tenant's
right to obtain any reduction or abatement of rent as permitted hereunder (iv)
limit, impair or delay Tenant Is right to terminate this Lease as permitted
hereunder or (v) otherwise unreasonably limit, impair or delay Tenant's rights
hereunder. Provided that Tenant pays all of Landlord's reasonable legal and
other related costs, Landlord will likewise agree to make reasonable non
material changes in this Lease to accommodate a mortgage of Tenant's leasehold
interest as contemplated under Section 5.2.1.

8.4  NO EXISTING MORTGAGE.

     Landlord warrants and represents that there is no existing mortgage
encumbering the Lot or Building.

                                  ARTICLE IX

                        LANDLORD'S ADDITIONAL COVENANTS

9.1  AFFIRMATIVE COVENANTS.

     Landlord covenants at all times during the Term:

     9.1.1     Perform Obligations.

          To perform promptly all of the obligations of Landlord set forth in
this Lease, including, without limitation, furnishing, through Landlord's
employees or independent contractors, the services (the cost of which is to be
included in the Annual Maintenance Charge) listed in Exhibit E;

                                     -35-
<PAGE>

     9.1.2     Repairs.

          Except as otherwise provided in Article VI, to make such repairs (the
cost of which is to be included in the Annual Maintenance Charge to the extent
contemplated in Section 4) to the roof, exterior walls, exterior windows and
waterproofing, other structural components and common areas and facilities of
the Building as may be necessary to keep them in good, serviceable condition.
Without limitation of the foregoing, Landlord shall be responsible for the
maintenance and repair of the heating and air-conditioning systems and the
components thereof serving the Building, except for such systems and the
components thereof as are located within the Premises or exclusively serve the
Premises (as provided in Section 5.1.3 hereof).

     9.1.3     Compliance with Law.

          To make all repairs, alterations, additions or replacements to the
Building or the Lot (the costs of which are to be included in the Annual
Maintenance Charge to the extent contemplated in Section 4) required by any law,
ordinance or order or regulation of any public authority including repairs,
alterations, additions or replacements to the foundations and structural
elements of the Building (which are not to be included in the Annual Maintenance
Charge), except as required because of Tenant's failure to comply with the
provisions of Section 5.1.3 hereof; to keep the Building equipped with all
safety appliances so required (the costs of which are to be included in the
Annual Maintenance Charge to the extent contemplated under Section 4); subject
to Section 4.2.1, to pay all municipal, county, or state taxes assessed against
the Building or the Lot, or against Landlord's personal property of any kind on
or about the Building or the Lot; and to comply with the orders and regulations
of all governmental authorities with respect to zoning, building, fire, health
and other codes, regulations, ordinances or laws applicable to the Building or
the Lot, including the ADA Requirements (as defined in Section 5.1.4 hereof) and
any codes, regulations, ordinances or laws relating to hazardous materials (as
defined in Section 5.1.4), subject to, and without limitation of, Tenant's
obligations with respect to such codes, regulations, ordinances or laws. The
costs incurred by Landlord in connection with the foregoing compliance
obligations shall be included in the Annual Maintenance Charge to the extent
contemplated under Section 4. All of the foregoing covenants and obligations are
subject to, and without limitation of, all of Tenant's obligations under this
Lease, including, without limitation, those set forth in Sections 4.2 and 5.1.4.

     9.1.4     Indemnity.

          To defend, with counsel reasonably approved by Tenant, all actions
against Tenant, any partner, trustee, stockholder, officer, director, employee
or beneficiary of Tenant ("Tenant's Indemnified Parties") with respect to, and
to pay, protect, indemnify and save harmless, to the extent permitted by law,
all Tenant's Indemnified Parties from and against any and all liabilities,
losses, damages, costs, expenses (including reasonable attorneys' fees and
expenses), causes of action, suits, claims, demands or judgments of any nature
to which any of Tenant's Indemnified Parties is subject arising from and to the
extent of any negligent or willful act, fault, omission, or other misconduct of
Landlord or its agents, contractors or employees.

                                     -36-
<PAGE>

     9.1.5     Estoppel Certificate.

          Upon not less than 10 days' prior notice by Tenant, to execute,
acknowledge and deliver to Tenant a statement in writing certifying that this
Lease is unmodified and in full force and effect and that except as stated
therein Landlord has no knowledge of any defenses, offsets or counterclaims
against its obligations under this Lease (or, if there have been any
modifications that the Lease is in full force and effect as modified and stating
the modifications and, if there are any defenses, offsets or counterclaims,
setting them forth in reasonable detail), the dates to which the Fixed Rent and
Additional Rent and other charges have been paid and a statement that, to the
best of Landlord's knowledge, Tenant is not in default hereunder (or if in
default, the nature of such default, in reasonable detail) and such other
matters reasonably required by Tenant or any prospective sublessee, assignee or
mortgagee of Tenant. Any such statement delivered pursuant to this Section 9.1.5
may be relied upon by any prospective sublessee, assignee or mortgagee.

     9.1.6     Utilities.

     The utilities serving the Premises shall be in "as is" condition.

                                   ARTICLE X

                           MISCELLANEOUS PROVISIONS

10.1 NOTICES FROM ONE PARTY TO THE OTHER.

     All notices required or permitted hereunder shall be in writing and
addressed, if to the Tenant, at the Original Address of Tenant or such other
address as Tenant shall have last designated by notice in writing to Landlord
and, if to Landlord, at Landlord's Address or such other address as Landlord
shall have last designated by notice in writing to Tenant. Any notice shall be
deemed duly given if mailed to such address postage prepaid, registered or
certified mail, return receipt requested, two (2) days after deposited with the
U.S. Postal Service, or if delivered by a recognized courier service (e.g.
Federal Express) when delivered by such courier service or if delivered by hand,
evidenced by a signed receipt.

10.2 QUIET ENJOYMENT.

     Landlord agrees that upon Tenant's paying the rent and performing and
observing the terms, covenants, conditions and provisions on its part to be
performed and observed, within applicable notice and grace periods Tenant shall
and may peaceably and quietly have, hold and enjoy the Premises during the Term
without any manner of hindrance or molestation from Landlord or anyone claiming
under Landlord, subject, however, to the terms of this Lease.

10.3 EASEMENTS; CHANGES TO LOT LINES.

     Landlord reserves the right, from time to time, to grant easements
affecting the Premises, or the Building or the Lot so long as such easements do
not materially interfere with Tenant's use of the Premises, and to enter upon
the Premises for purposes of constructing and maintaining any pipes, wires and
other facilities serving any portion of the Lot or of the Building, subject to
the terms of Section 5.1.7 hereof.

                                     -37-
<PAGE>

10.4 LEASE NOT TO BE RECORDED.

     Neither party shall record this Lease. Both parties shall execute and
deliver a notice of this Lease in such form, if any, as may be permitted by
applicable statute. If this Lease is terminated before the Term Expiration Date
the parties shall execute, deliver and record an instrument acknowledging such
fact and the actual date of termination of this Lease.

10.5 BIND AND INURE; LIMITATION OF LANDLORD'S LIABILITY.

     The obligations of this Lease shall run with the land, and this Lease shall
be binding upon and inure to the benefit of the parties hereto and their
respective successors and assigns. No owner of the Premises shall be liable
under this Lease except for breaches of Landlord's obligations occurring while
owner of the Premises. The obligations of Landlord shall be binding upon the
assets of Landlord which comprise the Premises but not upon other assets of
Landlord. No partner, trustee, stockholder, officer, director, employee or
beneficiary (or the partners, trustees, stockholders, officers, directors or
employees of any such beneficiary) of Landlord shall be personally liable under
this Lease and Tenant shall look solely to Landlord's interest in the Premises
and the rents, issues and profits therefrom, in pursuit of its remedies upon an
event of default hereunder, and the general assets of the partners, trustees,
stockholders, officers, employees or beneficiaries (and the partners, trustees,
stockholders, officers, directors or employees of any such beneficiary) of
Landlord shall not be subject to levy, execution or other enforcement procedure
for the satisfaction of the remedies of Tenant; provided that the foregoing
provisions of this sentence shall not constitute a waiver of any obligation
evidenced by this Lease and provided further that the foregoing provisions of
this sentence shall not limit the right of Tenant to name Landlord or any
individual partner or trustee thereof as part defendant in any action or suit in
connection with this Lease so long as no personal money judgment shall be asked
for or taken against any individual partner, trustee, stockholder, officer,
employee or beneficiary of Landlord.

10.6 ACTS OF GOD.

     In any case where either party hereto is required to do any act, delays
caused by or resulting from the occurrence of one or more Force Majeure Events
shall not be counted in determining the time during which work shall be
completed, whether such time be designated by a fixed date, a fixed time or a
"reasonable time", and such time shall be deemed to be extended by the period of
such delay.

10.7 LANDLORD'S DEFAULT.

     Landlord shall not be deemed to be in default in the performance of any of
its obligations hereunder unless it shall fail to perform such obligations and
such failure shall continue for a period of 30 days following receipt of notice
from Tenant or such additional time as is reasonably required to correct any
such default after notice has been given by Tenant to Landlord specifying the
nature of Landlord's alleged default. Landlord shall not be liable in any event
for incidental or consequential damages to Tenant by reason of any default by
Landlord hereunder, whether or not Landlord is notified that such damages may
occur. Except as expressly set forth in Section 3.2 and Section 6.2 hereof,
Tenant shall have no right to terminate this Lease for any

                                     -38-
<PAGE>

default by Landlord hereunder and no right, for any such default, to offset or
counterclaim against any rent due hereunder.

10.8  BROKERAGE.

      Each party warrants and represents to the other party that it has had no
dealings with any broker or agent in connection with this Lease and covenants to
defend with counsel reasonably approved by such other party, hold harmless and
indemnify such other party from and against any and all cost, expense or
liability arising from any breach of the foregoing warranty and representation.

10.9  APPLICABLE LAW AND CONSTRUCTION.

      This Lease shall be governed by and construed in accordance with the laws
of the state in which the Premises are located. If any term, covenant, condition
or provision of this Lease or the application thereof to any person or
circumstances shall be declared invalid, or unenforceable by the final ruling of
a court of competent jurisdiction having final review, the remaining terms,
covenants, conditions and provisions of this Lease and their application to
persons or circumstances shall not be affected thereby and shall continue to be
enforced and recognized as valid agreements of the parties, and in the place of
such invalid or unenforceable provision, there shall be substituted a like, but
valid and enforceable provision which comports to the findings of the aforesaid
court and most nearly accomplishes the original intention of the parties.

      There are no prior oral or written agreements between Landlord and Tenant
affecting this Lease. This Lease may be amended, and the provisions hereof may
be waived or modified, only by instruments in writing executed by Landlord and
Tenant.

      The titles of the several Articles and Sections contained herein are for
convenience only and shall not be considered in construing this Lease.

      Unless repugnant to the context, the words "Landlord" and "Tenant"
appearing in this Lease shall be construed to mean those named above and their
respective heirs, executors, administrators, successors and assigns, and those
claiming through or under them respectively. If there be more than one tenant
the obligations imposed by this Lease upon Tenant shall be joint and several.

10.10 SUBMISSION NOT AN OFFER.

      The submission of a draft of this Lease or a summary of some or all of its
provisions does not constitute an offer to lease or demise the Premises, it
being understood and agreed that neither Landlord nor Tenant shall be legally
bound with respect to the leasing of the Premises unless and until this Lease
has been executed by both Landlord and Tenant and a fully executed copy
delivered to each of them.

10.11 SECURITY DEPOSIT.

      Upon execution of this Lease, Tenant shall deposit the Security Deposit
Amount with the Landlord or a letter of credit in the same amount in a form
acceptable to Landlord in Landlord's

                                     -39-
<PAGE>

reasonable discretion. The issuer of the Letter of Credit shall be a banking
institution with at least a rating of A and otherwise reasonably acceptable to
Landlord. Although Landlord shall only have the right to draw under the Letter
of Credit in the event of a default as set forth herein, under the terms of the
Letter of Credit, the sole condition to Landlord's draw upon the Letter of
Credit shall be presentment to the issuer thereof, prior to or on the expiration
date, of a demand for payment. The Letter of Credit shall be self-renewing from
year to year during the term of this Lease so as to expire no earlier than
thirty (30) days following the Lease expiration date and shall contain such
other customary terms as Landlord requires in its reasonable discretion,
including, but not limited to, a provision that the Letter of Credit is
transferable to Landlord's successors and assigns. For and during the Term,
Landlord shall have the irrevocable right, without further notice or approval of
Tenant but not the obligation from time to time without prejudice to any other
remedy Landlord may have on account thereof, to apply the Security Deposit or
any portion thereof or interest thereon, to Landlord's damage resulting from any
default after applicable grace and cure periods by Tenant. On termination of the
Term, the Security Deposit, or the portion thereof then held by Landlord shall
be returned to Tenant, beyond the amount necessary to cure the breach of an
provision of this Lease by Tenant. If all or any part of the Security Deposit is
applied to an obligation of Tenant hereunder, Tenant shall immediately upon
request by Landlord restore the Security Deposit to its original amount. Tenant
shall not have the right to call upon Landlord to apply all or any part of the
Security Deposit to cure any default or fulfill any obligation of Tenant, but
such use shall be solely in the discretion of Landlord. Upon any conveyance by
Landlord of its interest under this Lease, the Security Deposit shall be
delivered by Landlord to Landlord's grantee or transferee. Upon any such
delivery, Tenant hereby releases Landlord herein named of any and all liability
with respect to the Security Deposit, its application and return, and Tenant
agrees to look solely to such grantee or transferee. It is further understood
that this provision shall also apply to subsequent grantees and transferees.

10.12  OPTIONS TO EXTEND.

       (a) Tenant shall have one (1) option to extend the Term of this Lease
(the "Option to Extend") for a period of five (5) years (the "Extension
Period"), subject to and on the terms set forth herein. Tenant may only exercise
the Option to Extend with respect to the entire Premises. If Tenant shall desire
to exercise the Option to Extend, it shall give Landlord a notice (the "Inquiry
Notice") of such desire not later than fifteen (15) months prior to the
expiration of the Initial Term of this Lease. Thereafter, the Fair Market Rent
(as defined in Subsection (c) below) for the Extension Period shall be
determined in accordance with Subsection (d) below. After the Fair Market Rent
has been so determined, Tenant shall exercise the Option to Extend by giving
Landlord notice (the "Exercise Notice") of its election to do so not later than
twelve (12) months prior to the expiration of the Initial Term of this Lease. If
Tenant fails to timely give either the Inquiry Notice or the Exercise Notice to
Landlord with respect to the Option to Extend, Tenant shall be conclusively
deemed to have waived such Option to Extend hereunder.

       (b) Notwithstanding any contrary provision of this Lease, the Option to
Extend and any exercise by Tenant thereof shall be void and of no force or
effect unless on the dates Tenant gives Landlord its Inquiry Notice and Exercise
Notice for the Option to Extend and on the date of commencement of the Extension
Period (i) this Lease is in full force and effect, (ii) there is no Event of
Default of Tenant under this Lease, and (iii) Tenant has not assigned or
subleased (or

                                     -40-
<PAGE>

agreed to assign or sublease) more than fifty percent (50%) of the rentable
floor area then comprising the Premises.

     (c)  All of the terms, provisions, covenants, and conditions of this Lease
shall continue to apply during the Extension Period, except that the Annual
Fixed Rent Rate during the Extension Period (the "Extension Rent") shall be
equal to the fair market rent for the Premises determined as of the date twelve
(12) months prior to expiration of the Initial Term in accordance with the
procedure set forth in Subsection (d) below (the "Fair Market Rent").

     (d)  The Fair Market Rent for the Extension Period shall be determined as
follows: Within five (5) days after Tenant gives Landlord its Inquiry Notice
with respect to the Option to Extend, Landlord shall give Tenant notice of
Landlord's determination of the Fair Market Rent for the Extension Period.
Within ten (10) days after Tenant receives such notice, Tenant shall notify
Landlord of its agreement with or objection to Landlord's determination of the
Fair Market Rent, whereupon the Fair Market Rent shall be determined by
arbitration conducted in the manner set forth below. If Tenant does not notify
Landlord within such ten (10) day period of Tenant's agreement with or objection
to Landlord's determination of the Fair Market Rent, then the Fair Market Rent
for the applicable Extension Period shall be deemed to be Landlord's
determination of the Fair Market Rent as set forth in the notice from Landlord
described in this subsection.

     (e)  If Tenant notifies Landlord of Tenant's objection to Landlord's
determination of Fair Market Rent under the preceding subsection, such notice
shall also set forth a request for arbitration and Tenant's appointment of a
commercial real estate broker having at least ten (10) years experience in the
commercial leasing market in the City of Cambridge, Massachusetts (an
"Arbitrator"). Within five (5) days thereafter, Landlord shall by notice to
Tenant appoint a second Arbitrator. Each Arbitrator shall be advised to
determine the Fair Market Rent for the Extension Period within thirty (30) days
after Landlord's appointment of the second Arbitrator. On or before the
expiration of such thirty (30) day period, the two Arbitrators shall confer to
compare their respective determinations of the Fair Market Rent. If the
difference between the amounts so determined by the two Arbitrators is less than
or equal to ten percent (10%) of the lower of said amounts then the final
determination of the Fair Market Rent shall be equal to the average of said
amounts. If such difference between said amounts is greater than ten percent
(10%0 , then the two arbitrators shall have ten (10) days thereafter to appoint
a third Arbitrator (the "Third Arbitrator") , who shall be instructed to
determine the Fair Market Rent for the Extension Period within ten (10) days
after its appointment by selecting one of the amounts determined by the other
two Arbitrators. Each party shall bear the cost of the Arbitrator selected by
such party. The cost for the Third Arbitrator, if any, shall be shared equally
by Landlord and Tenant. In no event shall the rent for the Extension Period be
less than the rent paid by Tenant under the Lease during the lease year prior to
commencement of the Extension Term.

10.13  RIGHT OF FIRST REFUSAL.

     Provided that at the time Tenant exercises its rights under this Section:
(i) there is then outstanding no Event of Default of Tenant under this Lease,
and (ii) Tenant has not assigned or subleased more than fifty percent (50%0 of
the rentable floor area then comprising the Premises, and provided that any and
all rights of first refusal of other tenants in the Building have elapsed,

                                     -41-
<PAGE>

specifically TVisions, Inc.'s right of first refusal for Suite 23, then in the
event that Landlord receives any written offer (an "Offer") from any third party
(a "Third Party Offeror") to lease (i) any space on the second floor in the
Building which may thereafter become available to lease or (ii) additional space
added to the Building as a result of an addition to the Building ("Available
Space"), Landlord shall have such offer memorialized in writing and furnish
Tenant with a notice (the "ROFR Notice") accompanied by a copy of such written
offer offering Tenant the option to lease such Available Space on the terms and
conditions specified in the Offer (a "Right of First Refusal")and otherwise are
the terms and conditions of this lease.  In the event Tenant elects to exercise
its Right of First Refusal with respect to any such Available Space, Tenant
shall send to Landlord notice of such election together with a certified or bank
check in the amount of one-twelfth (1/12) of the annual fixed rent rate for said
Available Space (as set forth in the Offer) and said Available Space shall
thereafter be leased to Tenant on the terms and conditions set forth in the
Offer.  In the event such notice and check are not sent to Landlord within five
(5) business days after the ROFR Notice with respect to any such Available
Space, or if after giving notice of election of its Right of First Refusal with
respect to any such Available Space, Tenant shall fail to perform its obligation
to lease such Available Space, then Landlord may retain the deposit delivered by
Tenant and may lease said Available Space to the Third Party Offeror, or any
affiliate thereof, upon the terms and conditions contained in the Offer.

10.14  CONFIDENTIAL INFORMATION.

       Landlord hereby agrees that any and all knowledge, information, data,
materials, trade secrets, and other work product of a confidential nature
gained, obtained, derived, produced, generated or otherwise acquired by Landlord
with respect to Tenant's business (collectively "Confidential Information")
shall be kept confidential.  Landlord shall use diligent efforts to ensure that
no Confidential Information is revealed, divulged, communicated, related, or
described to any person or entity without the written consent of Tenant, except
as may be required by applicable law.

10.15  SIGNAGE.

       Tenant shall be permitted, at its sole cost and expense, to install and
maintain a sign on the exterior of the Building, provided that: (i) the size,
location, quality, color and style of such signs shall be subject to Landlord's
approval, such approval not to be unreasonably withheld or delayed, and (ii)
such sign shall be subject to limitations of applicable law, including, without
limitation, the Cambridge Zoning By-Law, as amended from time to time.  Tenant
shall secure all permits necessary for the installation of such sign at its sole
cost and expense.  Upon the expiration or sooner termination of the Term of this
Lease, Tenant shall remove such signs and repair any damage resulting therefrom
at Tenant's sole cost and expense.

10.16  PARKING.

       A parking garage (the "Garage") is planned for construction at the
property known as 47 Erie Street, Cambridge, Massachusetts, which property is
controlled by Landlord. Upon completion of the Garage for occupancy, Tenant
shall be obligated to lease up to fifty (50) parking spaces from Landlord or
such other entity to be designated by Landlord at a fair market rent. Fair
market rent for parking spaces for motor vehicles is estimated at this time to
be

                                     -42-
<PAGE>

$130.00 per space per month. Beginning September 25, 1997, until completion of
                                                 --
the Garage, Tenant may lease up to twenty-five (25) surface parking spaces in
the parking lot located at 40 Erie Street, Cambridge, Massachusetts, at a cost
of $75.00 per space per month. In addition, in the event Tenant expands its
Premises as provided in this Lease, Tenant shall be entitled to lease one (1)
additional parking space in the Garage per each 650 square feet of additional
space added to the Premises at the fair market rent set forth above.

     In the event Landlord or its affiliate is unable to provide parking spaces
in the Garage due to failure to construct or complete the construction of the
Garage, Landlord shall be obligated to provide parking spaces for use by Tenant
as required under this provision within three hundred (300) feet of the
buildings owned or controlled by Landlord or its affiliates at 21 Erie Street,
270 Albany Street, 200 Sidney Street 40 Erie Street and 47 Erie Street,
Cambridge, Massachusetts, at the prevailing market rate for such spaces.

                                     -43-
<PAGE>

     WITNESS the execution hereof under seal on the day and year first above
written.

                    LANDLORD:


                             /s/ David E. Clem
                             ----------------------------------------------
                             David E. Clem, Trustee of 21 Erie Realty Trust


                    TENANT:  REPROGENESIS, INC.


                             By: /s/
                                -------------------------------------------
                                Its:
                                hereunto duly authorized

                                     -44-
<PAGE>

                                   EXHIBIT A
                                   ---------

                                LEASED PREMISES
                                ---------------
<PAGE>

                                  EXHIBIT A-2
                                  -----------

                            LEGAL DESCRIPTION OF LOT
                            ------------------------

Parcel 1
--------

A certain parcel of land with the buildings thereon situated in Cambridge,
Middlesex County, Massachusetts and being shown as Lot "A" on a Plan entitled
"Subdivision of Land in Cambridge dated September 20,1961, drawn by Edward
Smith, Surveyor, 517 School Street, Belmont." recorded with Middlesex South
District Registry of Deeds, Book 9910, Page 526 and bounded and described as
follows:

NORTHEASTERLY   by Merriam Street, Eighty-five and sixty-six one hundredths
                (85.66) feet

SOUTHEASTERLY   by Waverly Street, Two hundred (200.00) feet;

SOUTHWESTERLY   by Erie Street, One hundred twenty-five (125.00) feet;

NORTHWESTERLY   by land of owners unknown One hundred, two and fourteen one
                hundredths (102.14) feet;

NORTHEASTERLY   by Lot "B" as shown on said plan by line running through the
                center of a twelve (12) inch brick partition wall. Thirty-eight
                and thirteen one-hundredths (38.13) feet; and

NORTHWESTERLY   by said Lot "B" by a line running through the center of a twelve
                (12) inch brick partition wall, Ninety-seven and eighty-six one-
                hundredths (97.86) feet.;

Containing Twenty-one thousand, two hundred and eight (21,208) square feet of
land.

Parcel 2
--------

A certain parcel of land with the buildings thereon situated in Cambridge,
Massachusetts, and bounded and described as follows:

Beginning at a point in the southwesterly line of Merriam Street, said point
being distant eighty-five and sixty-six one hundredths (85.66) feet from the
intersection of the southwesterly line of Merriam Street and the northwesterly
line of Waverly street;

                                                       Exhibit A-2...Page 1 of 2
<PAGE>

Thence running in a southwesterly direction partly through the center of a
twelve (12) inch brick partition wall ninety-seven and eighty-six one hundredths
(97.86) feet to a point;

Thence running in a northwesterly direction through the center of a twelve (12)
inch brick partition wall thirty-eight and thirteen one hundredths (38.13) feet
to a point;

Thence running in a southwesterly direction two and fourteen one hundredths
(2.14) feet to a point;

Thence running in a northwesterly direction fifteen and sixty-one hundredths
(15.61) feet;

Thence turning and running in a northeasterly direction one hundred (100.00)
feet to a point in the southwesterly line of Merriam Street:

Thence running in a southeasterly direction along the southwesterly line of
Merriam Street fifty-three and seventy-four one hundredths (53.74) feet to the
point of beginning.

The above described parcel of land containing five thousand two hundred and
ninety-two (5,292) square feet is shown as Lot "B" on a Plan entitled
"Subdivision of Land in Cambridge dated September 20, 1961, drawn by Edward
Smith, Surveyor, 511 School Street, Belmont."  Recorded, with Middlesex South
District Registry of Deeds, Book 9910, Page 526.

                                                       Exhibit A-2...Page 2 of 2
<PAGE>

                                   EXHIBIT B

                            PLANS AND SPECIFICATION
                            -----------------------

     The floor plan annexed hereto represents the general design that is
intended to be implemented by Tenant in its Leasehold Improvements to the
Premises, comprising office, laboratory and light manufacturing space.  There
will, without limitation, include modifications of and supplements of the
utilities and services that are available in the Premises, and consequently
there will be additions to and further distribution of electrical power through
the Building to serve the Premises.  The Leasehold Improvements will include,
without limitation, construction, demolition and relocation of partition walls,
as well as additions to and modifications of plumbing and drains.  The floor of
the Premises will, among other things, be modified to allow the installation of
new floor drains and to assure a perfectly level surface.  The plans and
specifications for all of the work described herein shall be subject to
Landlord's approval as contemplated in Section 3.1 of the Lease.
<PAGE>

                                   EXHIBIT C

                             RULES AND REGULATIONS
                             ---------------------

1.   The entrances, lobbies, elevators, sidewalks, and stairways of the Building
     shall not be encumbered or obstructed by Tenant, Tenant's agents, servants,
     employees, licensees or visitors or used by them for any purposes other
     than ingress or egress to and from the Building.

2.   Landlord reserves the right to have Landlord's structural engineer review
     Tenant's floor loads on the Building at Tenant's expense.

3.   Tenant, or the employees, agents, servants, visitors or licensees of Tenant
     shall not at any time place, leave or discard any rubbish, paper, articles,
     or objects of any kind whatsoever outside of the Building except in the
     dumpster provided by Landlord.  Bicycles shall not be permitted in the
     Building, but shall be parked in the bicycle rack provided by Landlord.

4.   Tenant shall not place objects against glass partitions or doors or windows
     or adjacent to any common space which would be unsightly from the exterior
     of the Building and will promptly remove the same upon notice from
     Landlord.

5.   Tenant shall not make noises, cause disturbances, create vibrations, odors
     or noxious fumes or use or operate any electric or electrical devices or
     other devices that emit sound waves or that would interfere with the
     operation of any device or equipment or radio or television broadcasting or
     reception from or within the Building or elsewhere, or with the operation
     of roads or highways in the vicinity of the Building and shall not place or
     install any projections, antennae, aerials, or similar devices inside or
     outside of the Building, without the prior written approval of Landlord.

6.   Tenant shall not: (a) use the Building for lodging, or for any immoral or
     illegal purposes; (b) use the Building to engage in the manufacture or sale
     of spirituous, fermented, intoxicating or alcoholic beverages in the
     Building; (c) use the Building to engage in the manufacture or sale of, or
     permit the use of, any illegal drugs on the Building.

7.   No awning or other projections shall be attached to the outside walls or
     windows. No curtains, blinds, shades, screens or signs other than those
     furnished by Landlord shall be attached to, hung in, or used in connection
     with any exterior window or door of the Building without prior written
     consent of Landlord.

8.   Except as otherwise set forth in Lease, no sign, advertisement, object,
     notice or other lettering shall be exhibited, inscribed, painted or affixed
     on any part of the outside or inside of the Building if visible from
     outside of the Building.

9.   Door keys for doors in the Building will be furnished on the Commencement
     Date by Landlord. If Tenant shall affix additional locks on doors then
     Tenant shall furnish Landlord with copies of keys for said locks.
<PAGE>

EXHIBIT C                                                            Page 2 of 2

10.  Tenant shall cooperate and participate in all reasonable security programs
     affecting the Building.

11.  Tenant assumes full responsibility for protecting its space from theft,
     robbery and pilferage, which includes keeping doors locked and other means
     of entry to its space in the Building closed and secured.

12.  The water and wash closets and other plumbing fixtures shall not be used
     for any purposes other than those for which they were constructed, and no
     sweepings, rubbish, rags, or other substances shall be thrown therein.

13.  Tenant may request heating and/or air conditioning during other periods in
     addition to Normal Business Hours by submitting its request to the Landlord
     no later than 2:00 p.m. the preceding work day (Monday through Friday) on
     forms available from the Landlord. The request shall clearly state the
     start and stop hours of the "off-hour" service. Tenant shall submit to the
     Landlord a list of personnel authorized to make such request.

14.  Discharge of industrial sewage shall only be permitted if Tenant, at its
     sole expense, shall have obtained all necessary permits and licenses
     therefor, including without limitation permits from state and local
     authorities having jurisdiction thereof.

15.  Tenant may not (without Landlord's approval therefor, which approval will
     be signified on Tenant's Plans submitted pursuant to the Lease) and Tenant
     shall not permit or suffer anyone to (a) cook in the Premises; (b) place
     vending or dispensing machines of any kind in or about the Premises; (c) at
     any time sell, purchase or give away, or permit the sale, purchase or gift
     of food in any form. Notwithstanding the foregoing Tenant shall be
     permitted to use coffee machines, microwave ovens, dishwasher,
     refrigerator, sandwich and snack vending machines, soda machines and other
     similar appliances on the Premises.

16.  Subject to Tenant's right to make alterations in accordance with the
     provisions of the Lease Tenant shall not mark, paint, drill into, or in any
     way deface any part of the Building or Premises. No boring, driving of
     nails or screws, cutting or stringing of wires shall be permitted except
     with the prior written consent of Landlord not to be unreasonably withheld,
     and as Landlord may direct. Tenant shall not install any resilient tile or
     similar floor covering in the Premises except with the prior written
     approval of Landlord not to be unreasonably withheld. The use of cement or
     other similar adhesive material is expressly prohibited.

17.  Building employees shall not be required to perform, and shall not be
     requested by any tenant or occupant to perform, any work outside of their
     regular duties, unless under specific instructions from the office of the
     Managing Agent of the Building.

18.  In the event of any conflict between the provisions of this Exhihit C and
                                                                 ----------
     the provisions of the Lease, the provisions of the Lease shall govern.

                                      -2-
<PAGE>

                                   EXHIBIT D
                                   ---------

                               FLOOR LOAD LIMITS
                               -----------------
<PAGE>

                                   EXHIBIT E
                                   ---------

                              LANDLORD'S SERVICES
                              -------------------

I.   Exterior Maintenance
     --------------------

     Landlord shall keep the Lot and Common Areas of the Building clean and free
     of debris.

     Landlord shall keep the sidewalks, driveways and parking areas reasonably
     clear of snow and ice.

     Landlord shall maintain the exterior landscaping, lighting, parking areas,
     exterior roof, slab, foundation, exterior doors and windows, and sidewalks
     of the Building and the Lot in good repair and condition consistent with
     facilities of the size and quality of the Building and the Lot in the
     Cambridge, Massachusetts area.

II.  Mechanical, Electrical and Plumbing
     -----------------------------------

     Subject to the provisions of Section 5.1.3 of the Lease, Landlord shall
     maintain in good repair and condition the mechanical, electrical and
     plumbing systems for the Building.

III. Priority
     --------

     In the event of any conflict between the provisions of this Exhibit E and
                                                                 ---------
     the provisions of the Lease, the provisions of the Lease shall govern.

IV.  Cleaning
     --------

     Landlord shall keep clean and neat the public areas of the Building and
     Lot, including, without limitation, the restrooms.
<PAGE>

                                   EXHIBIT F
                                   ---------

  COMMENCEMENT DATE               SUITE #                    AREA
  -----------------               -------                    ----

September 25, 1997                 1.5                   4,953 r.s.f.

October 1, 1997                    2.4                     898 r.s.f.
                                   2.5                   5,282 r.s.f.
                                   2.6                     971 r.s.f.

January 1, 1998                    1.1                  14,731 r.s.f.
                                   1.2                   1,282 r.s.f.
                                   1.3                     640 r.s.f.
                                   1.4                   2,367 r.s.f
                                   2.9                   1,601 r.s.f
                                                       --------------
                                                 TOTAL  32,725 r.s.f.
<PAGE>

                           FIRST AMENDMENT TO LEASE


          This First Amendment to Lease (this "Amendment") is executed by and
between David E. Clem and David M. Roby, Trustees (the "Landlord") of 21 Erie
Realty Trust u/d/t dated May 16, 1996, recorded with the Middlesex South
District Registry of Deeds in Book 26325, Page 504, and Reprogenesis, Inc. (the
"Tenant"), a Texas corporation, in amendment of a Lease dated September, 1997
(the "Lease") by and between Landlord and Tenant with respect to a portion of
the building known as and numbered 21 Erie Street, Cambridge, Massachusetts (the
"Building").

          For good and valuable consideration, the receipt and legal sufficiency
of which is hereby acknowledged, Landlord and Tenant hereby agree as follows:

     1.   Each capitalized term which is used but not defined herein shall have
the respective meaning ascribed thereto in the Lease.

     2.   Commencing November 1, 1998 (the "Effective Date") and continuing
through and including the Term Expiration Date, Landlord hereby leases and
demises to Tenant, and Tenant hereby leases from Landlord, Suite No. 22,
consisting of approximately 2,645 rentable square feet of space on the Second
Floor of the Building (the "Additional Premises"), as more particularly shown on
Exhibit A attached hereto and incorporated herein by reference thereto. From and
after the Effective Date, except as set forth in this Amendment, the term
"Premises" as used in the Lease shall be deemed to include the Additional
Premises and the Additional Premises shall be subject to all of the terms,
covenants and conditions set forth in the Lease, including Section 10.12
thereof.

     3.   As of the Effective Date, the Annual Base Rent Rate for the Additional
Premises shall be $14.00 per rentable square foot, (the "Additional Premises
Annual Base Rent"). The Additional Premises Annual Base Rent shall be subject to
adjustment as set forth in Section 4.1(b) of the Lease and shall be subject to
all other provisions of the Lease with respect to Annual Base Rent Rate,
including the time and manner of payment thereof, except that with respect to
the Additional Premises the Base Price Index shall mean and refer to the Price
Index most recently established prior to January 1, 1999.

     4.   As of the Effective Date, the term "Tenant's Proportionate Share" set
forth in Article I of the Lease shall be amended by deleting "66.4%" therefrom
and by inserting in place thereof "71.5%".

     5.   The Additional Premises shall be delivered to Tenant by Landlord on an
"As Is, Where Is" basis with all faults and without representation, warranty or
guaranty of any kind by Landlord to Tenant.

     6.   If Tenant elects to extend the Term of the Lease pursuant to
Section 10.12 of the Lease, such extension shall and must relate to the Premises
demised pursuant to the Lease and the Additional Premises demised hereby.
<PAGE>

     7.   Simultaneously with the execution hereof, Tenant shall pay to Landlord
$12,343.33 representing a security deposit for the Additional Premises (the
"Additional Premises Security Deposit Amount"). Upon receipt thereof, references
in the Lease to "Security Deposit Amount" shall include the Security Deposit
Amount delivered in connection with the execution of the Lease and the
Additional Premises Security Deposit Amount, both of which shall be subject to
all of the provisions of the Lease, including Section 10.11 thereof.

     8.   Each party warrants and represents to the other party that it has had
no dealings with any broker or agent in connection with this Amendment and
covenants to defend with counsel reasonably approved by such other party, hold
harmless and indemnify such other party from and against any and all cost,
expense or liability arising from any breach of the foregoing warranty and
representation.

     9.   The Lease, as amended hereby, is hereby ratified, confirmed and
approved in all respects.

          WITNESS the execution hereof under seal as of the 1st day of October,
1998.

               LANDLORD:


                        /s/ David E. Clem, Trustee
                        ---------------------------------------------
                        David E. Clem, Trustee as aforesaid and not
                        individually


                        ________________________________________
                        David M. Roby, Trustee as aforesaid and not
                        individually


               TENANT:  REPROGENESIS, INC.



                        /s/ William D. Romeo
                        --------------------------------------------------
                        Its: Chief Operating Officer
                             hereunto duly authorized
<PAGE>

                                   EXHIBIT A

                       Floor Plan of Additional Premises

                                  (attached)