<Page>

                                                                Exhibit 10.05

[CONFIDENTIAL TREATMENT REQUESTED] /*/ INDICATES MATERIAL THAT HAS BEEN OMITTED
AND FOR WHICH CONFIDENTIAL TREATMENT HAS BEEN REQUESTED. ALL SUCH OMITTED
MATERIAL HAS BEEN FILED WITH THE SECURITIES AND EXCHANGE COMMISSION PURSUANT TO
RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

                                                                    CONFIDENTIAL

                            COMMERCIAL BUILDING LEASE

     This Lease made as of the 20th day of July 2004, by and between 890 East
LLC, a Massachusetts limited liability company, having a place of business at
120 Lumber Lane, Tewksbury, Massachusetts (hereinafter referred to as
"LANDLORD"), and Acusphere, Inc., a Delaware corporation, having a place of
business at 500 Arsenal Street, Watertown, Massachusetts 02472 (hereinafter
referred to as "TENANT").

                                   WITNESSETH

     1.     EXHIBITS--The following exhibits are attached to this Lease and
made a part hereof:

            Exhibit A--Description of PREMISES and Expansion Property.
            Exhibit B--Terms of Extension Periods.

     2.     PREMISES--LANDLORD hereby demises and leases unto TENANT and TENANT
hereby hires from LANDLORD, subject to the conditions hereinbelow set forth, the
PREMISES, together with the right to use all sidewalks, parking areas,
easements, rights of way and other means of access to and from public ways and
adjoining properties being the entire 58,398 square foot building (the
"BUILDING")] now commonly known and numbered as 890 East Street, Tewksbury,
Massachusetts and more particularly described in Exhibit A (hereinafter called
"the PREMISES"), and subject to a certain short term lease by and between 890
East LLC and Muro Pharmaceutical, Inc., a copy of which is attached hereto as
Exhibit B.

     To the extent that the "as is" condition of the PREMISES leased to TENANT
includes furniture, such furniture are considered part of the PREMISES. To the
extent, if any, that TENANT desires to remove such LANDLORD provided furniture,
it will do so in coordination with the LANDLORD.

     To the extent that any Expansion Property (as defined in Section 30 hereof)
is added to the space demised under such Lease, such Expansion Property,
together with the original PREMISES, shall thereafter be referred to as the
"EXPANDED PREMISES."

     The PREMISES and the Expansion Property constitute LANDLORD'S entire
holdings (the "Landlord Development") at 890 East Street. In calculating the
payment of Taxes and
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CAM, TENANT'S Proportionate Share relating to the Premises before the addition
of any Expansion Property shall be seventy-seven and one-half percent (77.5%).

     3.     TERM--TO HAVE AND TO HOLD, the PREMISES for an original term of
five (5) years and nine (9) months unless sooner terminated or extended as
hereinafter provided (the "TERM"). The Term shall commence on August 1, 2004
(the "Commencement Date") and expire on April 30, 2010, unless further extended
hereunder.

     3.1.   OPTION OF LANDLORD TO DEEM HOLDOVER RENEWAL OF LEASE OR TO REMOVE
TENANT.--If TENANT holds over for more than one day after the Term (or any
Extension Period) expires without LANDLORD'S consent, LANDLORD may either deem
such holdover a renewal of this Lease for an additional term of one year under
the same terms, covenants, and conditions in effect under the Lease immediately
prior to such holdover thereof or take all required steps to remove TENANT from
the PREMISES.

     4.     EXTENSION OPTION--TENANT shall have two (2) five (5) year options
to extend the term of this Lease (such extension period individually referred to
as an "EXTENSION PERIOD" and collectively referred to as the "EXTENSION
PERIODS") commencing upon the day after the expiration date of the then original
term and extension period, if applicable, provided that TENANT shall not be in
default under any of the terms of this Lease beyond applicable grace periods at
the time of the exercise of this option, and that TENANT continues to occupy the
PREMISES. If TENANT elects to exercise this option, it shall do so by giving
written notice of such election to LANDLORD at any time during the term of this
Lease before the date which is twelve (12) months prior to the commencement of
the EXTENSION PERIOD for which such election is exercised. Such EXTENSION
PERIODS shall be upon the terms and conditions set forth in Exhibit C of this
Lease.

     5.     RENT--TENANT agrees to pay LANDLORD as base rent for the PREMISES
the amounts set forth below. Until further notice from LANDLORD, all rent and
other payments due hereunder to LANDLORD shall be payable by check to "890 East
LLC" located at 120 Lumber Lane, Tewksbury, Massachusetts 01876.

Annual base rent for the initial lease term shall be as follows:

<Table>
<Caption>
                                                                        ANNUAL RENT      MONTHLY RENT
                                                                        -----------      ------------
<S>                                 <C>                                <C>              <C>
Initiation Period (9 months)        August 1, 2004 - April 30, 2005         NONE             NONE

First Year (12 months)              May 1, 2005 - April 30, 2006       $408,786.00      $34,065.50

Second Year (12 months)             May 1, 2006 - April 30, 2007       $467,184.00      $38,932.00

Third Year (12 months)              May 1, 2007 - April 30, 2008       $525,582.00      $43,798.50

</Table>

                                        2
<Page>

<Table>
<S>                                 <C>                                <C>              <C>
Fourth Year (12 months)             May 1, 2008 - April 30, 2009       $583,980.00      $48,665.00

Fifth Year (12 months)              May 1, 2009 - April 30, 2010       $642,378.00      $53,531.50

</Table>

Said base rent shall be payable in equal monthly installments (one-twelfth
(1/12) of annual base rent) in advance on the first day of each month commencing
on May 1, 2005. Said base rental rate is net to LANDLORD with the TENANT being
responsible to pay to LANDLORD for additional rent and operating expenses as
described below in Section 6, including, but not limited to, Taxes, insurance,
utilities, and Common Area Maintenance ("CAM").

     6.     ADDITIONAL RENT--TAXES/INSURANCE, MAINTENANCE

     (A)    TENANT further agrees that during the original term of this Lease,
including the Initiation Period, and any EXTENSION PERIOD and for such further
time as TENANT shall hold the PREMISES, or any part thereof, TENANT shall pay to
LANDLORD, as additional rent, the following:

     (i)    TENANT'S Proportionate Share of all real estate taxes and
            tax-related assessments whatsoever, except betterment assessments
            (collectively "Taxes"), assessed against the LANDLORD during the
            term of this Lease and for such further time as TENANT shall hold
            the PREMISES or any part thereof, LANDLORD hereby agreeing to
            furnish TENANT with copies of all bills for such Taxes, as well as
            copies of information pertaining to any abatement of such Taxes. All
            payments for Taxes shall be made directly by LANDLORD to the
            appropriate taxing authority upon receipt of tax installment bills.
            Within a reasonable time, LANDLORD shall furnish TENANT with a
            statement of TENANT'S Proportionate Share of such Taxes, along with
            a copy of LANDLORD'S payment. Within thirty (30) days of receipt,
            TENANT shall reimburse LANDLORD for TENANT's Proportionate Share of
            such Taxes for said tax installment bills. TENANT shall be liable
            for any interest or penalty charges incurred by LANDLORD which may
            result from late payment of said reimbursement of Taxes by TENANT.
            In addition to the foregoing, TENANT shall be solely responsible for
            all personal property taxes of every nature imposed upon all
            fixtures, equipment and other personal property of every nature on
            the PREMISES belonging to TENANT. At TENANT'S good faith request or
            upon the independent determination of LANDLORD, LANDLORD shall seek
            an abatement of such Taxes. TENANT shall be entitled to receive,
            from LANDLORD, TENANT'S Proportionate Share of any abatement or
            refund of said Taxes for any tax year for which TENANT shall have
            paid a portion to LANDLORD any amount of said Taxes, less reasonable
            expenses, including reasonable attorneys' fees incurred by LANDLORD
            in obtaining such abatement. If TENANT requests that LANDLORD seek
            such an abatement, and the

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            abatement is not successful, then TENANT shall reimburse LANLDORD
            for reasonable expenses, including reasonable attorneys' fees,
            incurred in prosecuting such abatement attempt.

     (ii)   LANDLORD shall obtain and TENANT shall, within thirty (30) days of
            receipt of an invoice, reimburse LANDLORD for TENANT'S Proportionate
            Share of all insurance related to the building as set forth in
            Section 12.

     (iii)  TENANT further agrees that during the original term of this LEASE,
            including the Initiation Period, and any EXTENSION PERIOD and for
            such further time as TENANT shall hold the PREMISES, or any part
            thereof, TENANT shall pay directly to the provider thereof all
            charges for heat, water & sewer, gas, electricity and all other
            utilities services furnished to the PREMISES. Upon LANDLORD'S
            written request, the TENANT shall furnish to the LANDLORD official
            receipts or other satisfactory proof of payment within a reasonable
            time after the LANDLORD'S demand.

     (iv)   TENANT further agrees that during the Term of this LEASE, excluding
            the Initiation Period, and any EXTENSION PERIOD and for such further
            time as TENANT shall hold the PREMISES, or any part thereof, TENANT
            shall reimburse LANDLORD for TENANT's Proportionate Share of all
            reasonable CAM costs incurred by LANDLORD, including costs relating
            to those items depicted on Exhibit D. It is understood that CAM is
            not intended to cover any capital improvements to the PREMISES. It
            is understood that CAM costs shall not be marked-up from their
            actual costs by LANDLORD. Attached hereto as Exhibit D is a proposed
            CAM budget for the remainder of 2004, which includes line items for
            each category of services for which LANDLORD shall seek CAM
            reimbursement, including LANDLORD'S management fee (the "Management
            Fee"). The Management Fee for Landlord Development shall not exceed
            [CONFIDENTIAL TREATMENT REQUESTED] /*/ ($ [CONFIDENTIAL TREATMENT
            REQUESTED] /*/) for the first twelve (12)months of the lease, nor
            shall the management fee increase by more than [CONFIDENTIAL
            TREATMENT REQUESTED] /*/ percent ([CONFIDENTIAL TREATMENT REQUESTED]
            /*/ %) per year. Based on such line items on Exhibit D, LANDLORD
            shall invoice TENANT for the actual cost of the CAM incurred during
            any month for any lease year, or portion of a lease year, during
            the Term or any Extension Periods. TENANT shall not be responsible
            for any CAM charges incurred prior to the commencement of the Term
            or for any CAM charges in the months following the expiration of
            the Term or, if applicable, any Extension Periods.

     (B)    ALL OBLIGATIONS OF TENANT CONSIDERED ADDITIONAL RENT The foregoing
(i-iv) obligations of the TENANT shall be deemed to be additional rent
hereunder: all interest and penalties that may accrue on such items because of
the TENANT'S failure to pay the same; and all damages and expenses that LANDLORD
may incur because of TENANT'S default or failure to comply with the lease terms
shall also be due as additional rent within thirty (30) days of TENANT'S receipt
of an invoice specifying such interest, penalties,

                                        4
<Page>

damages or expenses and accompanied by reasonable documentation evidencing the
same. In the event of TENANT'S nonpayment of any of the foregoing, LANDLORD
shall have the same rights and remedies as it has for nonpayment of the base
rent.

     7.     LANDLORD'S WARRANTY/QUIET POSSESSION

     LANDLORD represents and warrants to TENANT that LANDLORD owns, manages,
controls and/or operates the PREMISES and has the lawful right and authority to
enter into this Lease and the right, power and interest in the PREMISES to allow
TENANT to make use of the PREMISES described herein for the entire term hereof
(including the EXTENSION PERIODS) subject to the lease attached hereto as
Exhibit B.

     If in the future it is determined that the PREMISES are not in compliance
with the Americans with Disabilities Act of 1991 (the "ADA") and notice is
received from any enforcement authority that compliance is necessary, LANDLORD
agrees to take such actions as are necessary to make the PREMISES compliant,
unless such non-compliance is a direct result of actions by TENANT or result
from a specific TENANT use of the PREMISES that would not be deemed
non-compliance for general use of the Building, in which case TENANT shall take
such actions as are necessary to make the PREMISES compliant. If any elevators
in the PREMISES are determined in the future to be not in compliance with the
ADA, LANDLORD and TENANT shall each be responsible for 50% of the costs to put
such elevator in compliance.

     At the commencement of the Term, the TENANT shall accept the building
improvements, and any equipment on or in the PREMISES, in their existing
condition. No representation, statement, or warranty, express or implied, has
been made by or on behalf of the LANDLORD as to such condition, or as to the use
that may be made of such PREMISES. In no event shall the LANDLORD be liable for
any defect in such property or for any limitation of its use.

     8.     TENANT'S FIXTURES/ALTERATIONS/IMPROVEMENTS

     (A)    TENANT'S IMPROVEMENTS.

            (i)    LANDLORD and TENANT acknowledge that LANDLORD has approved a
conceptual plan dated June 24, 2004, of TENANT's proposed tenant improvements
(as defined in Section 12 of this Lease, the "Tenant Improvements") at the
PREMISES (the "Conceptual Plan"); and

            (ii)   TENANT shall proceed to develop construction plans (the
"Construction Plans") to apply for a building permit for the Tenant Improvements
and to bid out such Tenant Improvement Work to a contractor. TENANT shall submit
the Construction Plans to LANDLORD. LANDLORD shall, within ten (10) days after
submittal by TENANT, either approve such Construction Plans or return them to
TENANT, with specific requirements to be included before such Construction Plans
can be approved, with a subsequent approval to be made within five (5) days of
receipt of such modified Construction Plans incorporating such

                                        5
<Page>

requirements. LANDLORD shall not unreasonably withhold, condition or delay its
approval of such Construction Plans. The failure of LANDLORD to respond within
such time frame shall be deemed approval of such Construction Plans.

     (B)    Other than the Tenant Improvements, TENANT shall not, except as
provided in Section 8(D) of this Lease, make any additions, alterations or
improvements in or to the PREMISES without the LANDLORD'S written consent. The
TENANT may remove or replace its movable trade fixtures, equipment,
manufacturing process equipment and any utilities or specialized equipment that
supports such manufacturing operations (collectively, "TENANT'S Equipment and
Fixtures") if it repairs any damage caused by the removal of such TENANT'S
Equipment and Fixtures. The TENANT'S failure to remove TENANT'S Equipment and
Fixtures or any of its property at the termination of this lease term may be
deemed abandonment of such property by the LANDLORD.

     (C)    PRECONDITIONS. Before commencing any work, including the Tenant
Improvements, or installing any of TENANT'S Equipment and Fixtures, TENANT
shall:

            (i)    PERMITS. Obtain the necessary consents, authorizations, and
licenses from federal, state, and/or municipal authorities having jurisdiction
over the work to be done. No work shall be started nor TENANT'S Equipment and
Fixtures installed until all such necessary consents, authorizations, and
licenses shall have first been duly obtained by the TENANT, its contractor, or
other persons doing the work or installing the equipment on the TENANT'S behalf;

            (ii)   CONTRACTS. Enter into a contract with its contractor and/or
other persons who will do the work and install TENANT'S Equipment and Fixtures.
Such contract will provide, among other things: that the work shall be done and
TENANT'S Equipment and Fixtures installed in a good workmanlike manner in
accordance with the Construction Plans or other plans and specifications
previously approved and consents, authorizations, and licenses previously
obtained; that the contractor or other persons above referred to will look
solely to TENANT for payment and TENANT will cause LANDLORD and the demised
premises to be free from all liens and claims of all persons furnishing labor or
furnishing materials therefore, or both. In connection with each payment under
such contract, TENANT shall obtain lien waivers in connection with any previous
payments made to such contractor or its subcontractor. At the written request of
LANDLORD, a copy of the contract and copies of such lien waivers shall be
furnished to LANDLORD;

            (iii)  INDEMNIFICATION. TENANT shall also indemnify and save
harmless the LANDLORD against all bills for labor performed, TENANT'S Equipment
and fixtures and material furnished to TENANT in connection with work and
against all liens, bills, or claims therefor or against the demised premises and
from and against all loss, damages, costs, expenses, suits, claims, and demands
whatsoever; and

            (iv)   LAWS; INSURANCE. In connection with the Tenant Improvements,
the installation of TENANT'S Equipment and Fixtures, and any further additions,
alterations or

                                        6
<Page>

improvements to the PREMISES, TENANT, at its expense, shall promptly comply with
all applicable federal, state, city, and other governmental laws, ordinances,
orders, and rules, and shall reimburse LANDLORD for all expenses incurred on
account of TENANT'S failure to comply. All such expenses incurred by LANDLORD
shall be deemed additional rent under this lease, which shall be due and payable
to LANDLORD on the first day of the month immediately following their payment by
LANDLORD. All persons who do work or install TENANT'S Equipment and Fixtures,
whether TENANT, its contractors, or other persons, must be fully covered by
workmen's compensation insurance, and the certificate therefore must be
furnished to LANDLORD before any such work is commenced. TENANT shall indemnify
and hold LANDLORD harmless from all claims for personal injury, death, or
property damage occurring during the progress, or as a result, of any work done
by or on behalf of TENANT in or about the demised premises.

     (D)    All TENANT'S Equipment and Fixtures, which may at any time be
installed or placed in or upon the PREMISES, by or at the expense of TENANT, are
and shall remain the property of TENANT, and TENANT shall remove the same and
repair all damage to the PREMISES caused by such installation and removal prior
to or at the expiration date of the term or the EXTENSION PERIOD of this Lease.

     Notwithstanding the foregoing, TENANT may make non-structural alterations,
additions or improvements to the PREMISES without the prior written consent of
LANDLORD; however, any alterations, additions or improvements that would affect
the structural integrity of the Base Building shall require LANDLORD'S prior
consent, which shall not be unreasonably withheld, conditioned or delayed.

     9.     ASSIGNING AND SUBLETTING--Except as provided herein, TENANT shall
not assign this Lease or any interest therein without the prior written consent
of LANDLORD. Such consent shall not be unreasonably withheld, conditioned or
delayed provided that (a) TENANT remains liable for all payments and other
obligations under this Lease, (b) TENANT is not at the time of such assignment,
letting or subletting in default under this Lease beyond applicable periods of
notice and cure, (c) LANDLORD has received 10 business days' prior written
notice of the assignment or sublease, (d) LANDLORD receives a true copy of the
assignment document, (e) the assignment or sublease is specifically by its terms
made subject to this Lease and (f) LANDLORD shall have the right, without
establishing priority and without relieving TENANT of liability hereunder, to
collect rentals directly from the assignee, or, if TENANT is in default of
rental or additional payments hereunder, to collect rentals directly from the
subtenant. No subletting by TENANT shall in any way impair the continuing
primary liability of TENANT hereunder, and no consent to any assigning or
subletting in a particular instance shall be deemed to be a waiver of the
obligation to obtain LANDLORD'S approval in the case of any other assignment or
subletting. To the extent that this Section 9 conflicts with the Leasehold
Mortgage Protections contained on Exhibit E attached hereto, such Leasehold
Mortgage Protections shall control.

     Notwithstanding the foregoing, TENANT shall have the right to assign this
Lease to an entity in which TENANT owns at least a fifty percent (50%) interest,
an entity which owns or

                                        7
<Page>

controls a fifty percent (50%) interest in TENANT, or an entity which is under
common control of TENANT, without LANDLORD'S consent. Furthermore, TENANT shall
have the right to assign this Lease to any entity which is formed as a result of
a merger or consolidation involving TENANT, or an entity which acquires
substantially all of the assets of TENANT, without further consent from the
LANDLORD, provided that the surviving entity following such merger or
consolidation or the entity which acquires all of the assets of TENANT has,
following the consummation of such transaction, a net worth equal to or greater
than that of TENANT immediately prior to such transaction. While no LANDLORD
consent is required for transactions described above in this subparagraph,
TENANT shall promptly notify LANDLORD of the occurrence of any such transaction
and shall provide LANDLORD, upon its written request, with any reasonable
additional information requested by LANDLORD in connection with such
transaction.

     10.    REPAIRS AND MAINTENANCE

     (A)    LANDLORD shall not have any obligation to make any repairs or
alterations to the PREMISES or any part thereof, except as otherwise expressly
provided in this Lease. Throughout the TERM and any EXTENSION PERIODS, TENANT
covenants and agrees to maintain the PREMISES and all additions and improvements
made upon them in such repair, order and condition as the same are in at the
commencement of said term or may be put in by LANDLORD or TENANT during the
continuance thereof, reasonable wear and tear, damage by fire or any other
casualty, taking by eminent domain, and items which LANDLORD is expressly
obligated to repair only excepted. Without limiting the generality of the
foregoing, TENANT's responsibilities shall include providing regular maintenance
and repairs to all heating, air conditioning, hot water and other equipment
serving the PREMISES as well as providing janitorial and cleaning services and
repairing any damage to the PREMISES not caused due to the negligence, fault or
misconduct of LANDLORD.

     TENANT shall not permit or commit any waste. If repairs are required to be
made by TENANT pursuant to the terms hereof, LANDLORD may demand that TENANT
make the same forthwith, and if TENANT refuses or neglects to commence such
repairs within 30 days after written notice and to complete the same within
reasonable dispatch after such demand, LANDLORD may (but shall not be required
to) make or cause such repairs to be made. If LANDLORD makes or causes such
repairs to be made, TENANT agrees that TENANT shall forthwith, within 30 days of
written demand, which demand shall include invoices or other reasonable evidence
of such sums expended by LANDLORD, pay to LANDLORD the cost thereof, and if
TENANT shall default in such payment, LANDLORD shall have the remedies provided
for the nonpayment or rent or other charges hereunder.

     (B)    LANDLORD covenants and agrees that LANDLORD will (i) provide the
services and perform the maintenance obligations identified on Exhibit D hereto
(for CAM reimbursement) and (ii) make all necessary repairs and replacements to
the structure of said building, and the roof (however, Tenant shall be
responsible for any and all damage caused by or as a result of work performed on
or about the roof by or on behalf of the Tenant. Tenant shall be

                                        8
<Page>

responsible for Tenant's failure to maintain the same.) TENANT shall be
responsible to make and pay for all other repairs and replacements.

     11.    FIRE, CASUALTY, EMINENT DOMAIN

     Should the PREMISES be damaged by fire or other casualty, the LANDLORD
shall restore the Base Building (as defined in Section 12 of this Lease), and
TENANT shall restore the Tenant Improvements (as defined in Section 12 of this
Lease). LANDLORD shall not be required to expend in excess of the Base Building
Insurance Proceeds and TENANT shall not be obligated to expend in excess of the
Tenant Improvement Insurance Proceeds (as such terms are defined in Section 12
of this Lease) in undertaking such restoration. LANDLORD and TENANT agree to
cooperate in connection with any such restoration to insure that the timing of
the restoration work and the coordination of permitting and construction work is
done in a manner to most efficiently and rapidly complete such restoration work.

     Notwithstanding the foregoing, if TENANT, in its reasonable judgment
determines that the Base Building and Tenant Improvements cannot be restored to
an operating manufacturing facility within four (4) months of such fire or other
casualty, than TENANT, by notice to LANDLORD, within sixty (60) days of such
fire or other casualty may elect not to undertake such restoration. In such
event, LANDLORD shall be relieved of its obligation to restore the Base Building
and this Lease shall terminate and the Tenant Improvement Insurance Proceeds
shall be disbursed as set forth in Section 12 hereof.

     When such fire or casualty renders the PREMISES substantially unsuitable
for their intended use, a proportionate abatement of rent shall be made.

     12.    INSURANCE

     (A)    TENANT at its own cost and expense shall also provide and maintain:

            (i)    Commercial general liability insurance having a minimum per
                   occurrence limit of $5,000,000 against all claims which may
                   be brought for bodily injury, death or damage to property of
                   third persons; and
            (ii)   Workers' Compensation Insurance or insurance required by
                   similar employee benefit acts as well as insurance having a
                   minimum per occurrence limit of $1,000,000 against all claims
                   which may be brought for personal injury or death of TENANT'S
                   employees.

     At the commencement of the TERM, TENANT shall deliver to LANDLORD
certificates of insurance evidencing coverage as required above. TENANT shall be
responsible for maintaining required insurance during the TERM and any EXTENSION
PERIODS thereafter and providing certificates to evidence the satisfaction of
this responsibility.

     (B)    LANDLORD will maintain, and ensure that its agents and contractors
maintain, reasonable levels of Workers' Compensation Insurance or insurance
required by similar

                                        9
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employee benefit acts with respect to any and all employees, agents and
contractors of LANDLORD who perform work at the PREMISES.

     (C)    TENANT also shall maintain property insurance covering property
damage. Covered property shall include all Tenant Improvements (as defined
before) and all other TENANT'S Equipment and Fixtures and personal property
utilized by TENANT at the PREMISES. Such insurance, with respect only to Tenant
Improvements, shall name Massachusetts Development Finance Agency
("MassDevelopment") (in its capacity as lender under a separate $2,000,000 loan
facility (the "MassDevelopment Loan")) as additional loss payees, as its
interests may appear. Such insurance shall be written on an "all risk" of
physical loss or damage basis including the perils of fire, extended coverage,
wind storms, vandalism, malicious mischief, sprinkler leakage, flood and
earthquake, for the full replacement cost value of the covered items and in
amounts that meet any co-insurance claim of the policies of insurance, with a
deductible amount not to exceed $100,000.00

     LANDLORD shall maintain, as to the Base Building, insurance written on an
"all risk" of physical loss or damage basis including the perils of fire,
extended coverage, wind storm vandalism, malicious mischief, sprinkler leakage,
flood and earthquake, and loss of rents for the full replacement cost value of
the covered items and in amounts that meet any co-insurance claim of the
policies of insurance, with a deductible amount not to exceed $100,000.00.

     During the term of the Lease, all Tenant Improvements shall remain the
property of TENANT; however, at the end of the Term (or any EXTENSION PERIODS)
or at the earlier termination of the Lease, all of such Tenant Improvements
shall become the property of LANDLORD.

     As used herein, Base Building shall mean the existing Building at 890 East
Street, Tewksbury, Massachusetts, the portion of the land comprising the
Landlord Development on which the Building is located, and any existing
improvements constructed thereon, as of the date of this Lease.

     As used herein, Tenant Improvements shall include all of the work performed
by TENANT at the PREMISES and approved by LANDLORD pursuant to the provisions of
Section 8 of this Lease, defined as the structural work, exterior closure work,
sanitary systems, interior finish work, building electrical systems and utility
systems, but excluding any of TENANT'S Equipment and Fixtures.

     As referenced in Paragraph 11 of this Lease, upon any fire or other
casualty the proceeds of the insurance carried by TENANT (the "Tenant
Improvement Insurance Proceeds") and LANDLORD (the "Base Building Insurance
Proceeds") may be utilized for restoration of the Base Building and the Tenant
Improvements. In the event that a decision is made not to undertake such
restoration, then all of the Base Building Insurance Proceeds shall be paid to
LANDLORD and the Tenant Improvement Insurance Proceeds shall be disbursed as
follows:

     First, to the repayment of the MassDevelopment Loan;

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     Second, to the cost of demolition and removal and repair of the Base
Building caused thereby of any Tenant Improvements (to the extent required by
LANDLORD); and

     Third, any remaining amount of Tenant Improvement Insurance proceeds shall
be paid to TENANT.

     (D)    Ten (10) days prior to the expiration of each such policy, TENANT
shall deliver a binder renewing each such policy, which binder shall provide
that at least ten days' written notice of any change in or cancellation thereof
shall be given by the insurance company to LANDLORD. TENANT shall pay the
premiums for renewal insurance and provide to LANDLORD a copy of the original
policy or certificate thereof and duplicate receipt evidencing payment thereof.

     (E)    At the commencement of the term of this Lease, LANDLORD will deliver
to TENANT the PREMISES insurable as called for herein in its current "as is"
condition; thereafter TENANT shall not violate or permit to be violated any of
the conditions or provisions of any such policy, and TENANT shall perform and
satisfy the requirements of the companies writing such policies so that at all
times companies of good standing satisfactory to LANDLORD shall be willing to
write and/or continue such insurance.

     13.    EMINENT DOMAIN

     (A)    LANDLORD agrees to promptly provide TENANT with copies of any
notices of taking or other information that become available to LANDLORD
regarding the potential loss of any portion of the PREMISES due to eminent
domain.

     (B)    In the event of any taking for any public or quasi-public use by
exercise of the right of eminent domain or by deed in lieu thereof between
LANDLORD and those having the authority to exercise such right (hereinafter
called "Taking") of the whole of the PREMISES then this Lease and the term
hereof shall cease and expire as of the date of such Taking and the base rent
under Section 5 and any additional rent and all other charges paid for a period
after such Taking shall be refunded to TENANT within ten (10) calendar days.

     (C)    In the event of Taking of a substantial part of the PREMISES or in
the event of a Taking so as to prevent or substantially prevent adequate access
to or the intended use of PREMISES, then TENANT may elect to terminate this
Lease by giving notice of termination to LANDLORD on or before the date which is
ninety (90) days after receipt by TENANT of notice that the Taking or denial or
diminishing of access or termination of the TENANT'S lease shall have occurred.
Upon the date specified in such notice of termination this Lease and the term
hereof shall cease and expire, and the base rent under Section 5 and any
additional rent and charges paid for a period after such date of termination
shall be refunded to TENANT within ten (10) calendar days.

                                       11
<Page>

     (D)    If this Lease be not terminated or if TENANT does not elect to
terminate this Lease as aforesaid then the award or payment for the Taking shall
be paid to and used by LANDLORD for restoration as hereinafter set forth and
LANDLORD shall promptly commence and with due diligence continue to restore the
PREMISES remaining after the Taking to substantially the same condition and
tenantability as existed immediately preceding the Taking. During the period of
any restoration, the base rent under Section 5, additional rent, and other
charges shall be abated justly and equitably. Nothing herein contained shall be
deemed or construed to prevent either LANDLORD or TENANT from enforcing and
prosecuting a claim for the value of its respective interest in any condemnation
proceedings.

     (E)    TENANT'S right to recover damages in case of any Taking, shall not
be affected, prejudiced, restricted or limited whether or not this Lease has
been terminated because of such Taking or is subject to termination. Nothing
herein contained shall prohibit TENANT (in addition to the foregoing) from
interposing and prosecuting in any condemnation proceeding, independent of any
claim of LANDLORD, claims for which the TENANT may be entitled to recover.
Furthermore, to the extent that TENANT makes improvements to the PREMISES,
LANDLORD will provide reasonable assistance to TENANT in seeking to recover
damages for any loss due to a Taking.

     14.    MORTGAGES--This Lease shall be subject and subordinate in all
respects, except for TENANT Improvements and other property of TENANT, to the
first mortgage granted by LANDLORD. Except for such encumbrance, this Lease
shall be subject and subordinate in all respects to all future mortgages granted
hereafter by LANDLORD, which may hereafter affect the PREMISES and each and
every of the advances which have heretofore been made or which may hereafter be
made thereunder, and to all renewals, modifications, consolidations,
replacements and extensions thereof, provided that the holder of any such
mortgage delivers to TENANT (provided there are no incurred defaults on the part
of TENANT) a written agreement in recordable form consenting to this Lease and
agreeing that TENANT shall not be disturbed or canceled at any time, except in
the event LANDLORD shall have the right to terminate this Lease under the terms
and provisions set forth herein, and agreeing further that proceeds of insurance
and taking awards be applied as provided for in this Lease. In confirmation of
such subordination, TENANT shall execute promptly, without cost or charge, any
reasonable instruments or certificates that LANDLORD or any mortgagee may
require.

     Within ten days after LANDLORD'S request, TENANT shall deliver in
recordable form a certification to any proposed mortgagee, trustee, or
purchaser, certifying that this Lease is in full force and effect and that there
are no defenses or offsets thereto, or stating those claimed by TENANT.

     (A)    MORTGAGE OF LEASE. TENANT is given and has the absolute right,
without LANDLORD'S consent, to mortgage its interest in this lease, except that
no such mortgage shall extend to or affect the fee, the reversionary interest,
or the estate of LANDLORD in and to any land or building and improvements, other
than the Tenant Improvements, now or hereafter erected on the leased property.

                                       12
<Page>

     Any leasehold mortgagee, including TENANT'S initial leasehold mortgagee,
MassDevelopment shall have the benefit of the leasehold mortgagee protection
provisions attached hereto as Exhibit E. Within ten (10) days of the request of
any leasehold mortgagee, LANDLORD shall deliver in recordable form a
certification to such leasehold mortgagee certifying that this Lease is in full
force and effect and that there are no defenses or offsets thereto, or stating
those claimed by LANDLORD.

     15.    TENANT'S COVENANTS. In addition to all other covenants and
agreements of TENANT contained herein, TENANT hereby covenants with LANDLORD
that:

     TENANT during the said term and for such further time as it shall hold the
PREMISES or any part thereof will pay all charges for trash removal, fire
sprinkler maintenance, heat, water, gas, electricity, sewerage, and all other
utilities services used by TENANT upon the PREMISES. Furthermore, LANDLORD
agrees to cooperate with TENANT in making any necessary utility connections
available to TENANT; provided LANDLORD shall incur no expense for same.

     TENANT will save LANDLORD harmless from all loss and damage occasioned by
the use of water in or escape of water from the PREMISES or by the bursting or
cracking of the water pipes, including the sprinkler system, if any, except for
such loss or damage caused by the gross negligence and willful misconduct of
LANDLORD, its agents, employees, servants, or contractors or LANDLORD'S failure
to properly make repairs required to be made by LANDLORD hereunder;

     TENANT at the expiration of said term will remove its goods and effects and
those of all persons claiming under it and will peaceably yield up to LANDLORD
the PREMISES and all additions and improvements made upon them (except those
which TENANT is permitted to remove hereunder) and leave them clean and in such
repair, order and condition as the same are in at the commencement of said term
or may be put in by LANDLORD or TENANT during the continuance thereof,
reasonable wear and tear and damage by fire or any other casualty or takings
excepted;

     TENANT will not commit any unreasonable nuisance on the PREMISES;

     TENANT will not carry on any business, trade or occupation upon the
PREMISES or make any use thereof which shall be unlawful or offensive or
contrary to any law or ordinance in force from time to time;

     TENANT will not do any act or thing upon the PREMISES which will make it
uninsurable against otherwise insured casualty or which, except for improvements
to the PREMISES and occupancy and reasonable use of the PREMISES, is liable to
increase the premium for casualty insurance on the PREMISES over the normal
premium at the time in question for the stipulated use of the PREMISES, and if
such premiums are increased, TENANT shall pay the reasonable amount of such
increase;

                                       13
<Page>

     TENANT will keep the PREMISES reasonably equipped with all safety
appliances required by law or ordinance, or any order or regulation of any
public authority because of the use made of the PREMISES;

     TENANT will, except only for LANDLORD responsibilities defined in Section
10, make all repairs, alterations and replacements so required, in a good and
workmanlike manner, and will promptly cause the release of or bond over any
liens that attach to the PREMISES as a result thereof;

     TENANT will obtain any authorizations or licenses required for TENANT'S use
or repair of the PREMISES;

     TENANT will permit LANDLORD or its agents, during the term during normal
business hours and with TENANT'S prior approval, which approval TENANT agrees
not to unreasonably withhold or delay (or at any time in the event of an
emergency), to enter to view the PREMISES and make repairs or improvements, but
LANDLORD will not be required to do so, except as otherwise expressly provided
in this Lease. It is understood and agreed by LANDLORD that, except in the event
of an emergency, that certain sections of the PREMISES (e.g. clean rooms) may
have access restrictions imposed in compliance with good manufacturing
procedures or as required by regulatory authorities;

     TENANT will permit LANDLORD to show PREMISES to others at mutually
agreeable times during normal business hours, and at any time during normal
business hours within one (1) year prior to the expiration of the term (as the
same may be extended), may affix to any suitable part of the exterior of the
PREMISES a notice of reasonable size for letting or selling the PREMISES and
keep the same as affixed without molestation by TENANT. It is understood and
agreed by LANDLORD that TENANT may require visitors to sign non-disclosure
agreements before touring portions of the PREMISES and that certain sections
(e.g. cleanrooms) of the PREMISES may have access restrictions imposed in
compliance with good manufacturing procedures or as required by regulatory
authorities.

     TENANT will permit LANDLORD to cure any breach (after the expiration of any
cure period) by the TENANT, and in the event of a breach, to pay the LANDLORD,
as additional rent, its reasonable expenses, including attorneys' fees, incurred
by LANDLORD in curing any breach or enforcing its rights hereunder within thirty
(30) days of TENANT'S receipt of an invoice therefor with supporting
documentation; and

     Notwithstanding anything to the contrary contained in this LEASE, TENANT
has had an opportunity to inspect the PREMISES and is fully and completely
satisfied with the condition thereof and agrees to accept the same in "as is"
condition and that the LANDLORD has no obligation to repair, replace, and/or
construct any portion of PREMISES except that necessary to (i) have the HVAC
system in working condition on the Commencement Date of LEASE; (ii) remove all
signage referring to the former tenant; and (iii) repair any holes to the
exterior of the building caused by such signage. Such repairs shall include
repairs to the area over the front entranceway where removal of prior signage
has led to some rust, holes and chipping of the

                                       14
<Page>

stucco exterior. At the expiration of the term, TENANT shall deliver the
PREMISES in "broom clean condition".

     16.    TENANT'S DEFAULT--Notwithstanding anything to the contrary in this
LEASE, LANDLORD may terminate this lease in any of the following circumstances:

     (a)    if any sum or sums due as rent or additional rent as herein provided
and set forth or any part thereof shall be unpaid for a period of ten (10) days
from the date said sum or sums are due and TENANT shall have failed to pay such
sums in full within ten (10) days after written notice of such default has been
given by LANDLORD to TENANT, or

     (b)    if TENANT shall violate or be in default in its observances or
performance of any of its covenants herein contained, except default in the
payment of base rent or additional rent, and shall have failed to take and
prosecute appropriate steps to reasonably remedy such breach or default within
twenty (20) days after written notice of such breach or default has been given
by LANDLORD to TENANT, or

     (c)    if the estate hereby created shall be taken on execution or other
process of law and shall not be redeemed for twenty (20) days after LANDLORD
shall have given TENANT written notice of such taking, or

     (d)    if TENANT be declared bankrupt or insolvent according to law,
however, in the case of the commencement of an involuntary bankruptcy, it shall
not be a default if TENANT causes such case to be dismissed within sixty (60)
days, or

     (e)    if any assignment shall be made of TENANT'S property for the benefit
of creditors, or

     (f)    if the PREMISES become vacant or deserted for a period of 90 days;
however, TENANT shall not be deemed to have vacated or deserted the PREMISES if
TENANT ceases manufacturing operations for any period of time, as long as TENANT
continues to pay rent and additional rent and otherwise perform its obligations
under this Lease

then, and in each of the above said cases (after the expiration of the aforesaid
ten (10) day or twenty (20) day period if applicable), LANDLORD lawfully may
(notwithstanding any waiver of any former breach of covenant or waiver of the
benefit hereof or consent in a former instance) immediately or at any time
thereafter while such default or other stipulation aforesaid continues and
without further demand or notice enter into and upon the PREMISES or any part
thereof in the name of the whole and repossess the same as of its former estate
and expel TENANT and those claiming through or under it and remove its effects
(forcibly if necessary) without being deemed guilty of any manner of trespass
and without prejudice to any remedies which might otherwise be used for arrears
of rent or preceding breach of covenant, and upon entry as aforesaid this Lease
shall terminate and TENANT covenants that in case of such termination under the
provisions of statute by reason of the default of TENANT, TENANT will forthwith
pay to LANDLORD all accrued base rent, additional rent, and all sums due and
owing and all

                                       15
<Page>

reasonable costs incurred by LANDLORD in removing TENANT and, on
the last day of each calendar month, the difference, if any, pay LANDLORD for
the deficiency between rental which would have been due for such month had there
been no such termination and the sum of the amount being received by LANDLORD as
rent from occupants of the PREMISES, if any.

     17.    USE AND OCCUPANCY--The PREMISES may be used and occupied in a manner
that is compatible and in compliance with all applicable Federal, state and
municipal laws and regulations. LANDLORD agrees not to restrict TENANT'S use of
the PREMISES provided that TENANT complies with all such laws and regulations.

     TENANT shall maintain and use the premises in accordance with all
applicable laws, ordinances, governmental rules and regulations, directions and
orders of governmental agencies having jurisdiction and shall at TENANT'S own
expense obtain and maintain in effect all permits, licenses and the like
required by applicable law for TENANT'S use.

     18.    SIGNS--TENANT shall have the right to install, maintain and replace,
at its own cost and expense, after the prior written consent of LANDLORD, such
consent not to be unreasonably withheld, conditioned or delayed in each
instance, such signs on the PREMISES and in common areas such as driveways,
parking areas and sidewalks as it determines, provided the same shall be in
compliance with all laws, orders, rules and regulations of all governmental
authorities having jurisdiction thereof.

     19.    NOTICES--Every notice, approval, consent or other communication
authorized or required by this Lease shall not be effective unless in writing
and sent by United States registered or certified mail, return receipt
requested, directed, if to TENANT, to the address listed below, or sent by a
recognized overnight courier service; and if to LANDLORD, at the address listed
herein or such other address as either party may designate by notice from time
to time.

If to LANDLORD:    890 East LLC
                   ATTENTION:  Joseph Phelan
                   120 Lumber Lane
                   Building #1
                   Tewksbury, MA 01876

with a copy to:    Mawn and Mawn, P.C.
                   ATTENTION:  James J. Mawn, Esq.
                   215 Lexington Street
                   Woburn, MA  01801

If to TENANT:      Acusphere, Inc.
                   Attention: Chief Financial Officer
                   500 Arsenal Street
                   Watertown, MA 02472

                                       16
<Page>

with a copy to:    Testa, Hurwitz & Thibeault, LLP
                   Attention: Lawrence S. Wittenberg, Esquire
                   125 High Street
                   Boston, MA 02110

with a copy to     MassDevelopment
                   75 Federal Street
                   Boston, MA 02110
                   Attention: _______________________________

     20.    WAIVER--One or more waivers of any covenant or condition by LANDLORD
or TENANT shall not be construed as a waiver of a subsequent breach of the same
or any other covenant or condition, and the consent or approval by LANDLORD
requiring the other party's consent or approval to or of any similar subsequent
act. The failure of either party to seek redress for violation of, or to insist
upon strict performance of, any term, covenant or condition in this Lease shall
not prevent a similar subsequent act from constituting a default under this
Lease.

     21.    INVALIDITY OF CERTAIN PROVISIONS--If any provision of this Lease
shall be invalid or unenforceable, the remainder of the provisions of this Lease
shall not be affected thereby and each and every provision of this Lease shall
be enforceable to the fullest extent permitted by law.

     22.    LANDLORD'S INTEREST--LANDLORD reserves the right to assign or
transfer any and all of its rights, title and interest under this Lease,
including but not limited to the benefit of all covenants of the TENANT
hereunder. Notwithstanding anything contained in this Lease to the contrary, it
is specifically understood and agreed that the obligations imposed upon LANDLORD
hereunder shall be binding upon LANDLORD and LANDLORD'S successors in interest
only with respect to breaches occurring during LANDLORD'S and LANDLORD'S
successors' respective ownership of LANDLORD'S interest hereunder, and LANDLORD
and its said successors in interest shall not be liable for acts and occurrences
arising from and after the transfer of their interest as LANDLORD hereunder.
LANDLORD further agrees to provide TENANT written notice of its intention to
transfer its interest in this Lease.

     23.    INDEMNIFICATION--TENANT agrees to indemnify and save LANDLORD
harmless against any and all bodily and personal injury, loss, claim or damage
to any person or property while on the PREMISES occasioned by any act, neglect
or omission of TENANT or its employees, agents, licensees, invitees or any other
person for whom TENANT is responsible, or occasioned by a default in the proper
performance of TENANT's obligation under the terms of this Lease. LANDLORD
agrees to indemnify and save TENANT harmless against any and all bodily and
personal injury, loss, claim or damage to any person or property occasioned by
any act, neglect or omission of LANDLORD or its employees, agents, licensees,
invitees or any other person for whom LANDLORD is responsible, in connection
with any work performed by LANDLORD in connection with said PREMISES.

                                       17
<Page>

     24.    ENVIRONMENTAL.

     (A)    The TENANT shall not violate and shall promptly remedy or correct
any federal, state or local laws, rules and regulations now or hereafter in
effect with respect to Hazardous Material introduced to the PREMISES by TENANT.
TENANT shall not use all or any portion of the PREMISES for the generation,
storage, treatment, use or disposal of any substance for which a license or
permit is required by Massachusetts General Laws, Chapter 21C without the prior
written consent of LANDLORD. Without limitation, express or implied under any
other requirements of this Lease, the TENANT shall pay all such sums and take
all such actions as may be required to avoid or discharge the imposition of any
lien on the PREMISES under Massachusetts General Laws, Chapter 21E,
Comprehensive Environmental Response, Compensation, and Liability Act, 42 U.S.C.
Section 9601 et seq., any so-called "Superfund" or "Superlien" law, or any other
federal, state, local or other statute, law, ordinance, code, rule, regulation,
order or decree regulating, relating to, or imposing liability or standards of
conduct concerning any Hazardous Material introduced to the PREMISES by TENANT,
and the TENANT shall indemnify and save harmless the LANDLORD from any and all
reasonable losses, claims, liabilities and expenses, including, without
limitation, reasonable attorneys' fees incurred or suffered by LANDLORD by
virtue of the provisions thereof as applied to the PREMISES. It is expressly
understood that TENANT shall have no responsibility for, and the foregoing
indemnification provisions shall not apply to, any Hazardous Material existing
on the Landlord Development, including the PREMISES, as of the date of this
Lease. The provisions of and undertakings and indemnification set forth in this
paragraph shall survive the early termination or expiration of this Lease.

     (B)    For purposes of this Lease, "Hazardous Material" means and includes
any hazardous substance or any pollutant or contaminant defined as such in (or
for purposes of) the Federal, state, or local statute, law, ordinance, code,
rule, regulation, order, or decree regulating, relating to, or imposing
liability or standards of conduct concerning, any hazardous, toxic or dangerous
waster, substance or material, as may now or at any time in the future be in
effect, or any other hazardous, toxic or dangerous, waste, substance, or
material.

     (C)    LANDLORD has provided TENANT with a Phase One Environmental Report
and a Phase Two Environmental Report (collectively, the "Environmental
Reports"), as more specifically identified on Exhibit F attached hereto. Other
than as set forth in such Environmental Reports, LANDLORD represents and
warrants to TENANT that (i) LANDLORD has not received any other written notice
from any person, entity or governmental authority, which notice indicates the
presence of any hazardous material on either the PREMISES or other portions of
the Landlord Development and (ii) Landlord has no other environmental reports or
studies other than the Environmental Reports.

     25.    NET LEASE--It is understood and agreed that TENANT, during the term
hereof, is to do all things and make all payments connected with the PREMISES or
arising out of any occupation of the PREMISES or any part thereof or its
appurtenances, except as otherwise expressly provided in this Lease, and under
no condition or contingency is LANDLORD to be

                                       18
<Page>

called upon to do or perform any act or action or be subject to any liability or
responsibility or to make any payments with respect to the PREMISES or any part
thereof, except as otherwise expressly provided in this Lease, all so that this
Lease shall yield net to LANDLORD the rent specified in this Lease, except as
otherwise expressly provided in this Lease.

     26.    REAL ESTATE BROKER--LANDLORD and TENANT each warrant and represent
to each other that neither has dealt with any real estate broker in connection
with this transaction except Hunneman Commercial Real Estate Services and
Spaulding & Slye Colliers International. Both parties agree to indemnify the
other against and to hold the other harmless from any claim, loss, damage, cost
or liability for any brokerage commission or fee which may be asserted against
either party in connection with this transaction by any other broker with whom
either party has dealt. LANDLORD shall be responsible to pay all applicable the
brokerage fee(s) as per separate written agreement.

     27.    SECURITY DEPOSIT--As security for its full and faithful performance
of this Lease, TENANT shall deliver to LANDLORD, prior to the commencement of
any work at the PREMISES, a security deposit in the form of either (a) a letter
of credit issued by a financial institution acceptable to the LANDLORD or (b) a
cash deposit to be held in escrow in an interest-bearing account at a financial
institution acceptable to LANDLORD, in either case in an amount equal to One
Million Dollars ($1,000,000.00). After TENANT has spent at lease Five Million
Dollars ($5,000,000) in the construction of the Tenant Improvements and the
installation of equipment in the PREMISES, then upon presentation by TENANT
to LANDLORD of paid invoices evidencing such amount, the Security Deposit
shall be reduced to One Hundred Two Thousand One Hundred Ninety-Six and
50/100 Dollars ($102,196.50). So long as TENANT is not in default under any
of the terms, provisions or conditions of this Lease on the expiration date
of the TERM or any EXTENSION PERIODS hereunder, LANDLORD will return the
deposit to TENANT at the expiration of the TERM or any EXTENSION PERIODS
thereof. If TENANT defaults with respect to any covenant or condition of this
Lease, including but not limited to the payment of Base Rent, Additional Rent
or any other payment due under this Lease, LANDLORD may apply all or any part
of the security deposit to the payment of any sum in default or any other sum
which LANDLORD may be required or deem necessary to spend or incur by reason
of TENANT'S default.

     28.    COUNTERPARTS--This Agreement may be signed on any number of
indicated counterparts with the same binding effect as if all of the signatures
were on one instrument.

     29.    SUBORDINATION AND NON-DISTURBANCE AGREEMENT--This lease is subject
and subordinate at all times to the lien of existing and future mortgages on the
leased property. Although no instrument or act by TENANT is necessary to effect
such subordination, TENANT shall, nevertheless, execute and deliver such further
instrument subordinating the lease to the lien of all such mortgages, in the
form reasonably desired by the mortgagee. TENANT hereby appoints LANDLORD its
attorney-in-fact, irrevocably, to execute and deliver any such instrument for
TENANT.

                                       19
<Page>

     (A)    NONDISTURBANCE. So Long as TENANT is not in default in the payment
of rent or additional rent or in the performance of any term of the lease,
TENANT'S possession of the leased property and its rights and privileges under
the lease or any renewal thereof shall not be diminished or interfered with by
any mortgagee.

     (B)    ATTORNMENT. If the mortgage is foreclosed for any reason, and any
mortgagee succeeds to LANDLORD'S interest under the lease, TENANT shall be bound
to the mortgagee under all of the terms of the lease for the balance of the
remaining term with the same force and effect as if mortgagee were the landlord
under the lease. TENANT hereby attorns to mortgagee as its landlord, such
attornment to be effective and self-operative, without the execution of any
further instrument by either party, as soon as mortgagee succeeds to the
landlord's interest under the lease. Notwithstanding any contrary provision
herein, TENANT shall Notwithstanding any contrary provision herein, TENANT shall
not be required to pay rent to the mortgagee until TENANT receives written
notice from mortgagee that it has succeeded to the landlord's interest under the
lease. The respective rights and obligations of TENANT and mortgagee upon such
attornment shall, to the extent of the then remaining balance of the lease term,
be the same as now set forth therein, it being the parties' intention for this
purpose to incorporate the lease in this agreement by reference with the same
force and effect as if set forth at length herein.

     30.    EXPANSION OPTION--In addition to the space defined as the PREMISES,
LANDLORD owns additional property that is adjacent to the PREMISES. Such
additional property consists of:

     (A)    Warehouse space located to the rear of the PREMISES (the
"warehouse");

     (B)    Unused land in the forested area that is behind the PREMISES (the
"unused land"); [the warehouse and the unused land being collectively referred
to as the "Expansion Property".]

It is understood that one of the inducements for TENANT entering into this lease
is the potential for the TENANT to expand its operations. Accordingly, provided
that TENANT is not then in default of this Lease, throughout the term of this
lease, including the EXTENSION PERIOD, TENANT will have a right of first refusal
to lease each of the warehouse and unused land from LANDLORD if the LANDLORD
should decide to lease the warehouse or unused land. Furthermore, LANDLORD
agrees not to lease or sell the unused land to any other party for a period of
three (3) years from the commencement date of this Lease. Notwithstanding the
above, in the event LANDLORD receives a bona-fide proposal from a third party to
lease or purchase the warehouse and/or unused land, LANDLORD agrees to provide
TENANT thirty (30) days' advance written notice of the terms of any bona-fide
proposal that LANDLORD is evaluating for the lease of the warehouse and/or
unused land such that TENANT will have sufficient time to elect to match such
proposal. If, after thirty days from notice, TENANT elects not to match such
third-party proposal, TENANT's right of first refusal will expire with respect
to the subject warehouse or unused land. However, if LANDLORD does not then
lease or sell such space

                                       20
<Page>

within thirty (30) days from the end of the thirty-day notice period, TENANT's
first refusal rights for such space shall be reinstated under the same terms as
though it had not expired.

     Notwithstanding the above, if at any time during the term of this lease,
including the EXTENSION PERIOD, TENANT notifies LANDLORD that TENANT desires to
lease the warehouse or unused land, LANDLORD and TENANT agree to enter into good
faith negotiations regarding commercially reasonable lease terms and to use
their best efforts to enter into a lease for such Expansion Property.

     If during the term of lease and extension thereof, LANDLORD elects to sell
the Building or the entire Landlord Development, TENANT shall have a right of
first refusal to match any bona fide proposal on the terms and conditions set
forth above.

     31.    The LANDLORD will consider funding a portion of the TENANT'S
buildout to the PREMISES (the "TENANT'S Buildout"); however, LANDLORD'S
consideration of such funding shall be subject to the following terms and
conditions:

A.   TENANT must request in writing to LANDLORD the funding of a portion of such
     TENANT Buildout (the "TENANT Buildout Allowance").

B.   Prior to application, TENANT shall have caused all TENANT Improvements
     contemplated by paragraph 8 to be completed.

C.   The amount of any TENANT Buildout Allowance requested by TENANT shall not
     exceed [CONFIDENTIAL TREATMENT REQUESTED] /*/ Dollars ($[CONFIDENTIAL
     TREATMENT REQUESTED] /*/).

D.   This lease shall be in full force and effect and there shall be no uncured
     default.

E.   The TENANT Buildout Allowance shall be repaid over the remaining Term of
     the Lease, as set forth in Subsection 31(F) below.

F.   Upon the funding of the TENANT Buildout Allowance, the LEASE shall be
     amended as follows:

     (i)    the initial Term shall be extended to expire ten (10) years from the
            date of funding of the TENANT Buildout Allowance;

     (ii)   the base rent set forth in Section 5 of the LEASE shall be increased
            on a monthly basis to cover LANDLORD'S Cost of Funds for the TENANT
            Buildout Allowance; and

     (iii)  such other changes shall be made to the LEASE to reasonably
            implement the financial terms and conditions set forth in this
            Section 31.

G.   As used herein, "LANDLORD'S Cost of Funds" shall mean the amount that the
     base rent needs to be increased under this LEASE on a monthly basis to
     amortize the TENANT

                                       21
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     Buildout Allowance portion of the principal sum that LANDLORD will borrow
     pursuant to the LANDLORD Financing (defined below) over the ten (10) year
     term of the LEASE (as amended as set forth above) at an interest rate equal
     to the higher of [CONFIDENTIAL TREATMENT REQUESTED] /*/ % or the interest
     rate provided to the LANDLORD under such LANDLORD Financing, plus
     [CONFIDENTIAL TREATMENT REQUESTED] /*/ %.

H.   Upon application by TENANT, LANDLORD shall use diligent and good faith
     efforts to secure financing from a Lender(s) of LANDLORD's choosing
     (hereinafter "LANDLORD Financing"). Said LANDLORD Financing shall: (1) be
     on a non-recourse basis, (2) be secured only by the building known as 890
     East Street, Tewksbury and improvements thereto, (3) contain a term of
     years equal to the term of years contained in the LEASE as amended, (4)
     contain a rate acceptable to LANDLORD and TENANT, and (5) be used to pay
     off liens created by LANDLORD and to fund the TENANT Buildout Allowance.

I.   All costs associated with obtaining said LANDLORD Financing, including,
     without limiting the generality of the foregoing, all title examination
     fees, title insurance fees, certified plot plan fees, environmental report
     fees, appraisal fees, flood certification fees, pre-payment penalties
     contained in existing mortgage loans and recording fees shall be paid by
     TENANT. Upon application by TENANT, the LANDLORD shall provide TENANT with
     a good faith estimate of principal closing costs and the TENANT shall
     deposit [CONFIDENTIAL TREATMENT REQUESTED] /*/ ($ [CONFIDENTIAL
     TREATMENT REQUESTED] /*/) with LANDLORD to be applied toward said costs.
     LANDLORD shall refund to TENANT any portion of said deposit not applied
     to LANDLORD Financing Costs. TENANT shall fund any deficiencies between
     said deposit and monies actually expended by LANDLORD in obtaining
     LANDLORD Financing.

J.   This proposal to provide the TENANT Buildout Allowance is subject to
     LANDLORD'S ability to obtain LANDLORD Financing, LANDLORD'S review and
     satisfaction with TENANT'S Financial Condition at time of application and
     LANDLORD'S market due diligence. LANDLORD'S proposal to provide financing
     is subject to such modifications as may be dictated by said underwriting.

K.   In no case shall LANDLORD Financing exceed seventy (70%) percent of the
     value of the PREMISES as determined at the time of TENANT'S application.

L.   TENANT shall be required to provide certain financial reporting, including,
     without limitation, annual financial and operating statements prepared by a
     CPA acceptable to LANDLORD and quarterly statements of all changes in
     accordance with generally accepted accounting principles.

M.   TENANT shall upon request provide LANDLORD with such information as
     LANDLORD may request in order to satisfy reasonable investor requests.

                                       22
<Page>

N.   THIS PROPOSAL SHALL NOT CONSTITUTE NOR BE CONSTRUED TO BE A BINDING
     COMMITMENT BY LANDLORD. THE TENANT ACKNOWLEDGES THE ABOVE TERMS ARE NEITHER
     FINAL NOR ALL INCLUSIVE.

     32.    CONFIDENTIAL INFORMATION--In connection with this Lease, TENANT is
making available to LANDLORD certain confidential information regarding TENANT'S
technology, business and operations, construction schedule, manufacturing
processes, costs and other information which information may constitute
"material nonpublic information" as defined by the U.S. Securities and Exchange
Commission (collectively, the "Confidential Information").

     LANDLORD agrees to use the utmost degree of care to maintain and protect
any and all Confidential Information delivered to it and not to disclose this
Confidential Information to any third party. LANDLORD further agrees to use the
Confidential Information solely for the purposes of this Lease. LANDLORD will
disclose the Confidential Information only to those of its employees or agents
who require knowledge or access to the Confidential Information and who are
contractually bound to protect the confidentiality of such Confidential
Information. The LANDLORD will inform those employees or agents who have access
to the Confidential Information that such information is strictly confidential.
LANDLORD may not use or otherwise commercially exploit any of the Confidential
Information for any purpose other than the above-stated purpose.

     LANDLORD'S obligations as to Confidential Information not constituting
material nonpublic information shall not apply to any portion of the
Confidential Information: (a) of which the LANDLORD presently has knowledge and
of which it did not learn through its contact with TENANT previous to the date
of this Lease; (b) which is presently or becomes publicly available or a matter
of public knowledge generally, through no act or omission by the LANDLORD; (c)
which is lawfully received by the LANDLORD from a third party who is or was not
bound in any confidential relationship to TENANT or (d) which is independently
developed by the TENANT without reference to or reliance upon the Confidential
Information.

     33.    FAILURE TO ACHIEVE NECESSARY PERMITS--It is understood and
acknowledged that at the time that the parties enter into this LEASE that TENANT
has not had sufficient time to evaluate all potential local, state and federal
permits and approvals required for the construction and operations intended by
TENANT. Both TENANT and LANDLORD represent that, at the time of entering into
this lease, neither are aware of any required permit or approval that should
prevent TENANT from conducting such construction and operations in the timeframe
and manner for which they are planned. Notwithstanding the foregoing, if TENANT
or LANDLORD discover, on or before October 30, 2004, that if any required permit
or approval cannot be obtained in a reasonable period of time, TENANT may
terminate this LEASE. Upon such termination, TENANT'S continuing obligation to
LANDLORD will be limited to restoring the PREMISES to a condition which is
consistent with its condition at the beginning of the lease term, and after
performance of such obligation, the Security Deposit shall be returned to TENANT
and neither party shall have any additional obligations hereunder.

                                       23
<Page>

     34.    NOTICE OF LEASE--LANDLORD and TENANT agree, upon written request of
the other party, to execute a Notice of Lease pursuant to Massachusetts General
Laws, Chapter 183, Section 4, for recording with the Middlesex North Registry of
Deeds.

                           [SIGNATURE PAGE TO FOLLOW]

                                       24
<Page>

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

                                        LANDLORD:
                                        890 East LLC


                                        By /s/ Joseph J. Phelan, III
                                           -------------------------------------
                                            Joseph J. Phelan, III, Manager


                                        TENANT:


                                        Acusphere, Inc.


                                        By: /s/ Sheri C. Oberg
                                           -------------------------------------
                                           Sheri C. Oberg
                                           President and Chief Executive
                                             Officer

                                       25
<Page>

                                    EXHIBIT A

                             DESCRIPTION OF PREMISES

The Premises include the following:

1. The Building commonly known as 890 East Street containing 58,398 square feet,
more or less, as depicted on the attached plan.

2. Tenant Parking Areas as depicted on the attached plan.

The Expansion Property includes the following:

1. The Warehouse as depicted on the attached plan.

2. That portion of the forested land depicted as "Unused Land" on the attached
plan.

<Page>

                                    EXHIBIT C
                           TERMS OF EXTENSION PERIODS

     EXTENSION PERIOD resulting from the exercise of the option contained in
Section 4 shall be upon the same terms and conditions as the original term of
the Lease, except for the annual rent which will be $11.00 per rentable
square foot per year for the first five-year extension period and $12.00 per
rentable square foot per year for the second five-year extension period.


<Page>

                                    EXHIBIT D

                                2004 CAM CHARGES
                                 890 East Street
                                  Tewksbury, MA

LANDSCAPING        $27,500.00
-  Weekly mowing/maintenance
-  Site litter pick up
-  Spring clean up/mulch
-  Fertilizer
-  Tree shrub trimming
-  Lawn sprinkler system maintenance
-  Shrub/tree replacement

SNOWPLOWING        $22,000.00
-  Plowing
-  Shovel walks
-  Ice control
-  Snow removal

EXTERIOR BUILDING MAINTENANCE $15,000.00
-  Painting
-  Siding maintenance
-  Caulking

EXTERIOR LIGHTING  $4,500.00
-  Cleaning
-  Bulb replacement
-  Electrical

MANAGEMENT FEE     $20,000.00

PAVEMENT MAINTENANCE (AS NEEDED) $15,000.00
-  Sand sweeping
-  Stripping
-  Pothole repair
-  Seal coating
-  Curb repair

CHARGES PAID BY TENANT

Building insurance


<Page>

Fire/burglar monitoring
Fire sprinkler maintenance/testing
Trash
Water
Sewer
Interior maintenance/cleaning


<Page>

                                    EXHIBIT E

                         LEASEHOLD MORTGAGEE PROTECTIONS

     SECTION 1. TENANT and every successor and assignee of TENANT, and any
sublessee of all of the demised premises shall have the absolute and
unconditional right, without LANDLORD'S consent, from time to time, to mortgage
and finance and refinance its interest in this lease and/or its leasehold
interest in the demised premises, or any part or parts thereof, without
limitation as to amount and without limitation as to what the mortgage secures,
under one or more leasehold mortgages ("Leasehold Mortgage"), and the right to
assign unconditionally, collaterally or otherwise, this lease and any sublease
as collateral security for such Leasehold Mortgage, and in connection therewith,
to grant and convey TENANT'S interest in the TENANT Improvements, fixtures and
any building service equipment in such form as the holder of the Leasehold
Mortgage determines. All proceeds of any Leasehold Mortgage shall belong to
TENANT.

     For the purposes of this Article, the term "mortgage" shall include
mortgages, deeds of trust, assignments of the sublessor interest, and all
similar instruments, as well as security interests, including security interests
in personal property, and pledges and assignments of the lessee's interest in
this lease, and modifications, replacements and consolidations of any of the
foregoing, and the term "the demised premises" shall include the PREMISES as
defined in that certain Lease between 890 East LLC, as LANDLORD and Acusphere,
Inc., as TENANT dated July __, 2004.

     SECTION 2. The following shall apply in connection with Leasehold
Mortgages:

     (a)    There shall be no cancellation, surrender or modification of this
            Lease by joint action of LANDLORD and TENANT, without the prior
            consent in writing of the holder of a Leasehold Mortgage ("Leasehold
            Mortgagee").

     (b)    LANDLORD shall, upon serving TENANT with any notice of default,
            simultaneously serve a copy of such notice upon the Leasehold
            Mortgagee, if LANDLORD shall have been apprised in writing of the
            name and address of such Leasehold Mortgagee. The Leasehold
            Mortgagee shall thereupon have the right to remedy or cause to be
            remedied the defaults complained of, including reimbursement to
            LANDLORD for any costs or expenses incurred if payable by TENANT
            under such circumstances, and LANDLORD shall accept such performance
            by or at the instigation of the Leasehold Mortgagee as if the same
            had been done by TENANT, provided, however, that the Leasehold
            Mortgagee shall never be obligated so to do.

     (c)    If Landlord elects to terminate this lease by reason of any default
            of Tenant, the leasehold mortgagee shall not only have and be
            subrogated to all rights of Tenant with respect to curing such
            default, but shall also have the right to postpone and extend the
            specified date for the termination of this lease as fixed by
            Landlord in


<Page>

            its notice of termination, for a period of not more than six months,
            if: (1) the mortgagee cures any existing default, and meanwhile pays
            the rent and additional rent and performs all of Tenant's other
            obligations under this lease; (2) no further defaults accrue
            hereunder during such extended period; or (3) if the nature of the
            default is such that the mortgagee is unable to take reasonable
            steps to cure the same, the mortgagee immediately proceeds to
            acquire Tenant's interest in this lease by foreclosure of its
            mortgagee or otherwise.

     (d)    In the event of the termination of this Lease for any reason
            whatsoever, including without limitation default of TENANT, LANDLORD
            shall, except as hereinafter provided, enter into a new lease with
            the Leasehold Mortgagee or its nominee for the remainder of the term
            of this Lease effective as of the date of such termination of this
            Lease, at the rent and upon the covenants, agreements, terms,
            provisions and limitations herein contained, provided (i) such
            Leasehold Mortgagee makes written request for such new lease within
            sixty (60) days from the date of such termination, (ii) such
            Leasehold Mortgagee pays or causes to be paid to LANDLORD at the
            time of the execution and delivery of such new lease any and all
            sums which would at the time of the execution and delivery thereof
            be due under this Lease but for such termination, and pays or causes
            to be paid any and all reasonable expenses, including reasonable
            counsel fees, court costs and costs and disbursements incurred by
            the LANDLORD in connection with any such termination, (iii) cures
            any and all other defaults under this Lease reasonably susceptible
            of being cured by such holder (only defaults which can be cured by
            the expenditure of money being deemed reasonably susceptible of
            being so cured). Any such new lease shall be and remain an
            encumbrance on the demised premises having the same priority thereon
            as this Lease and shall be and remain subject to any lien, charge or
            encumbrance of the demised premises created by LANDLORD. The
            Leasehold Mortgagee, as tenant under such new lease, shall have the
            same rights, title and interest in and to the buildings and
            improvements on the demised premises as TENANT had under this Lease.
            If the Leasehold Mortgagee becomes the holder of the TENANT's
            interest, the Leasehold Mortgagee's liability extends only so long
            as it is the holder of the lessee interest under this Lease, and it
            shall be released of all further liability from and after the date
            of any assignment of such lessee interest.

     (e)    LANDLORD agrees that the name of the Leasehold Mortgagee may be
            added to the "Loss Payable Endorsement" of any and all insurance
            policies required to be initiated by TENANT hereunder. The proceeds
            from any insurance policies are to be held by any Leasehold
            Mortgagee and distributed pursuant to the provisions of this Lease,
            but the Leasehold Mortgagee may reserve its rights to apply to the
            mortgage debt all, or any part, of TENANT's share of such proceeds
            pursuant to such Leasehold Mortgage.

     (f)    LANDLORD shall, upon request, execute, acknowledge and deliver to
            each Leasehold Mortgagee, an agreement, in form reasonably
            satisfactory to such


<Page>

            Leasehold Mortgagee and LANDLORD, between LANDLORD, TENANT and
            Leasehold Mortgagee, agreeing to all of the provisions of this
            Section.

     (g)    The failure by any such Leasehold Mortgagee to exercise the right
            under any provision of this Lease shall not be deemed a waiver of
            its right under any other provision hereof.

     (h)    The right of a Leasehold Mortgagee to foreclose a Leasehold Mortgage
            and to sell or assign the lessee interest in this Lease is expressly
            recognized and shall never be deemed a violation of any provision of
            this Lease (but shall be subject to all of the terms and provisions
            of this Lease).

     (i)    Nothing contained herein shall be construed to relieve the Tenant
            from its obligations under this lease. It is understood that all
            obligations of Tenant shall continue whether or not a leasehold
            mortgage is foreclosed or otherwise affects Tenant's use of the
            property.

     SECTION 3. LANDLORD will, upon request of TENANT, execute, acknowledge,
seal and deliver any and all of the instruments to be executed by it, necessary
or required to effectuate the provisions of this Article, but nothing herein
contained shall require or permit LANDLORD to be or become liable on any
promissory note.