EXHIBIT 10.4


THIRD AMENDMENT TO PURCHASE AND SALE CONTRACT


THIS THIRD AMENDMENT TO PURCHASE AND SALE CONTRACT ("Amendment") is
entered into as of July 26, 2006, by and between TECHNOLOGY SQUARE FINANCE, LLC,
a Massachusetts limited liability company ("Seller") and ARE-MA REGION
NO. 31, LLC, a Delaware limited liability company ("Buyer").  

R E C I T A L S

WHEREAS, Seller and Buyer entered into that certain Purchase and Sale
Contract dated as of July 3, 2006, as amended by a First Amendment to Purchase
and Sale Contract (the "First Amendment") dated as of July 10, 2006 and a
Second Amendment to Purchase and Sale Contract (the "Second Amendment")
dated as of July 14, 2006  (as so amended, the "Agreement") with respect
to certain real and personal property (the "Property") located at
Technology Square, Cambridge, Massachusetts, which Property is more particularly
described in the Agreement; and 

WHEREAS, Seller and Buyer have agreed to amend the Agreement as more
particularly set forth below.

NOW, THEREFORE, for mutual consideration, the receipt and sufficiency of
which are hereby acknowledged by the parties, Seller and Buyer hereby amend the
Agreement as follows:


1.  Capitalized Terms.  Capitalized terms not defined herein shall have
the meanings ascribed to them in the Agreement.


2.  Additional Seller Deliveries at Closing.  Seller and Buyer hereby
agree that Seller shall deliver the following additional documents at the
Closing in accordance with the terms of Section 6.2 of the Agreement:


	A true, correct and complete list of all Space Leases in effect with respect
to the Premises, updated through the date of the Closing, in the form attached
to the Agreement as Exhibit T (the "Updated Rent Roll");




3.  Additional Seller Representations and Warranties.  Section 12.1 of
the Agreement is hereby amended by adding the following new representations and
warranties of Seller to Buyer under the Agreement as Subsections (l) and (m)
after the end of Subsection (k) and before the beginning of Section 12.2 of the
Agreement:


"(l) Seller has performed all obligations required to be performed by
Seller pursuant to the terms of that certain Agreement to Perform Closing
Obligations dated as of March 26, 2004, executed by Seller for the benefit of
Connecticut General Life Insurance Company and ING USA Annuity and Life
Insurance Company; and


(m)There currently exists no event of default on the part of Seller under
any of the Loan Documents, nor any condition which, with the passage of time or
the giving of notice, or both, would constitute an event of default on the part
of Seller under any of the Loan Documents.  To the best of Seller's knowledge,
there currently exists no event of default on the part of Lender under any of
the Loan Documents, nor, to the best of Seller's knowledge, any condition which,
with the passage of time or the giving of notice, or both, would constitute an
event of default on the part of Lender under any of the Loan Documents." 




4.  Revised First Amendment to Development Agreement.  Exhibit G
to the Second Amendment, the "Form of First Amendment to Development Agreement,"
is hereby deleted in its entirety and replaced with Exhibit G attached
hereto.


5.  Extension of Closing Date.  The first paragraph of Article 6 of the
Agreement is hereby amended by deleting therefrom the date "July 26, 2006" and
replacing it with the date "July 27, 2006."


6.  Counterparts.  This Amendment may be executed in one or more
counterpart copies, all of which counterparts shall have the same force and
effect as if all parties hereto had executed a single copy of this Amendment.



7.  Ratification.  Except as amended hereby, the Agreement shall remain
in full force and effect.



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IN WITNESS WHEREOF, the parties have executed this Amendment as of the day
and year first above written.



SELLER:

TECHNOLOGY SQUARE FINANCE, LLC, a Massachusetts limited
liability company


By:Massachusetts Institute of Technology, 

a Massachusetts charitable corporation, 

its Manager


By:   /s/ Steven C. Marsh

Name:  Steven C. Marsh

Its:  Managing Director, Real Estate













BUYER:

ARE-MA REGION NO. 31, LLC, a Delaware limited

liability company



By:Alexandria Real Estate Equities, L.P., 

a Delaware limited partnership, 

its Managing Member


By:ARE-QRS Corp., 

a Maryland corporation,

its General Partner



By:  /s/ Jennifer Pappas 

Name:  Jennifer Pappas

Its:  V.P. & Assistant Secretary














Acknowledgement by Escrow Agent



Escrow Agent acknowledges the terms of the foregoing Amendment, and agrees to
continue to be bound by those terms of the Agreement applicable to the Escrow
Agent.


ESCROW AGENT:

Chicago Title Insurance Company



By:  /s/ Gus Aguilar 

Name:  Gus Aguilar

Its:  AVP/Senior Escrow Officer