Document:

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                                                                   Exhibit 10.28

                                                                  EXECUTION COPY

                                 ACUSPHERE, INC.

                            INDEMNIFICATION AGREEMENT

         This Indemnification Agreement (the "Agreement") is made as of August
__, 2002, by and between Acusphere, Inc., a Delaware corporation (the
"Company"), and _____________ (the "Indemnitee").

         WHEREAS, in order to continue to attract and retain sophisticated and
experienced individuals to serve on its board of directors, the Company desires
to provide, independent from the indemnification to which the Indemnitee is
otherwise entitled by law and under the Company's Certificate of Incorporation,
as amended and in effect from time to time (the "Charter"), and By-Laws, as
amended and in effect from time to time (the "By-Laws"), indemnification to the
Indemnitee and advances of expenses, all as set forth in this Agreement to the
maximum extent permitted by law;

         NOW, THEREFORE, to induce the Indemnitee to continue to serve the
Company and in consideration of these premises and the mutual agreements set
forth in this Agreement, as well as other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the Company and the
Indemnitee hereby agree as follows:

         1. INDEMNIFICATION.

                  (a) Third Party Proceedings. The Company shall indemnify
Indemnitee if Indemnitee is or was a party or is threatened to be made a party
to any threatened, pending or completed action, suit or proceeding, whether
civil, criminal, administrative or investigative (other than an action by or in
the right of the Company) by reason of the fact that Indemnitee is or was a
director, officer, employee or agent of the Company, or of any subsidiary of the
Company, or by reason of the fact that Indemnitee is or was serving at the
request of the Company as a director, officer, employee or agent of another
corporation, partnership, joint venture, trust or other enterprise, against
expenses (including attorneys' fees), judgments, fines and amounts paid in
settlement (if such settlement is approved in advance by the Company, which
approval shall not be unreasonably withheld or delayed) actually and reasonably
incurred by Indemnitee in connection with such action, suit or proceeding if
Indemnitee acted in good faith and in a manner Indemnitee reasonably believed to
be in or not opposed to the best interests of the Company, and, with respect to
any criminal action or proceeding, had no reasonable cause to believe
Indemnitee's conduct was unlawful. The termination of any action or proceeding
by judgment, order, settlement, conviction, or upon a plea of nolo contendere or
its equivalent, shall not, of itself, create a presumption that Indemnitee did
not act in good faith and in a manner which Indemnitee reasonably believed to be
in or not opposed to the best interests of the Company, and, with respect to any
criminal action or proceeding, had reasonable cause to believe that Indemnitee's
conduct was unlawful.

                  (b) Proceedings by or in the Right of the Company. The Company
shall indemnify Indemnitee if Indemnitee was or is a party or is threatened to
be made a party to any threatened, pending or completed action or suit by or in
the right of the Company or of any
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                                      -2-

subsidiary of the Company to procure a judgment in its favor by reason of the
fact that Indemnitee is or was a director, officer, employee or agent of the
Company, or of any subsidiary of the Company, or by reason of the fact that
Indemnitee is or was serving at the request of the Company as a director,
officer, employee or agent of another corporation, partnership, joint venture,
trust or other enterprise, against expenses (including attorneys' fees) actually
and reasonably incurred by Indemnitee in connection with the defense or
settlement of such action or suit if Indemnitee acted in good faith and in a
manner Indemnitee reasonably believed to be in or not opposed to the best
interests of the Company, except that no indemnification shall be made in
respect of any claim, issue or matter as to which Indemnitee shall have been
finally adjudged to be liable to the Company unless and only to the extent that
the Delaware Court of Chancery or any other court in which such action or suit
is or was brought shall determine upon application that, despite the
adjudication of liability but in view of all the circumstances of the case,
Indemnitee is fairly and reasonably entitled to indemnity for such expenses
which the Court of Chancery or other such court shall deem proper.

                  (c) Mandatory Payment of Expenses. To the extent that
Indemnitee has been successful on the merits or otherwise in defense of any
action, suit or proceeding referred to in Section 1(a) or Section 1(b) or in
defense of any claim, issue or matter therein, Indemnitee shall be indemnified
against expenses (including attorneys' fees) actually and reasonably incurred by
Indemnitee in connection therewith.

         2. EXPENSES; INDEMNIFICATION PROCEDURE.

                  (a) Advancement of Expenses. The Company shall advance all
expenses incurred by Indemnitee in connection with the investigation, defense,
settlement or appeal of any civil or criminal action, suit or proceeding
referenced in Section 1(a) or Section 1(b) hereof (but not amounts actually paid
in settlement of any such action or proceeding). Indemnitee hereby undertakes to
repay such amounts advanced if, and to the extent that, it shall ultimately be
determined that Indemnitee is not entitled to be indemnified by the Company as
authorized hereby. The advances to be made hereunder shall be paid by the
Company to Indemnitee within twenty (20) days following receipt by the Company
of a written request of the Indemnitee, but only if the Company has first
received an undertaking (the "Undertaking"), substantially in the form attached
hereto as Exhibit 1, by or on behalf of the Indemnitee to repay the amount of
any such advance if and to the extent that it shall ultimately be determined
that the Indemnitee is not entitled to indemnification for such amount. The
Undertaking shall be unsecured and shall bear no interest and shall be accepted
without reference to the financial ability of the Indemnitee to make repayment.

                  (b) Notice/Cooperation by Indemnitee. Indemnitee shall, as a
condition precedent to his or her right to be indemnified under this Agreement,
give the Company notice in writing as soon as practicable of any claim made
against Indemnitee for which indemnification is or will be sought under this
Agreement. Notice to the Company shall be directed to the Chief Executive
Officer of the Company at the address shown on the signature page of this
Agreement (or such other address as the Company shall designate in writing to
Indemnitee). Notice shall be deemed received three (3) business days after the
date postmarked if sent by domestic certified or registered mail, properly
addressed; otherwise notice shall be deemed received when such
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                                      -3-

notice shall actually be received by the Company. In addition, Indemnitee shall
give the Company such information and cooperation as it may reasonably require
and as shall be within Indemnitee's power.

                  (c) Procedure. Any indemnification and advances provided for
in Section 1 and this Section 2 shall be made promptly, and in any event within
forty-five (45) days following receipt by the Company of a written request of
the Indemnitee (or within twenty (20) days in the case of advances made pursuant
to Section 2(a)), unless with respect to such requests the Company reasonably
determines within such applicable period that the Indemnitee did not meet the
applicable standard of conduct or that indemnification is not required under
Section 7 below, or unless otherwise ordered by a court. Such determination
shall be made in each instance by: (a) the board of directors by a majority vote
of a quorum consisting of directors of the Company who were not parties to such
action, suit or proceeding in question ("disinterested directors"); (b) if such
quorum is not obtainable, or even if obtainable if a quorum of disinterested
directors so directs, by independent legal counsel (who may be regular counsel
to the Company) in a written opinion; or (c) by the stockholders of the Company.
If a claim under this Agreement, under any statute, or under any provision of
the Company's Charter or By-Laws providing for indemnification, is not paid in
full by the Company within the applicable period, Indemnitee may bring an action
against the Company to recover the unpaid amount of the claim and Indemnitee
shall also be entitled to be paid for the expenses (including attorneys' fees)
of bringing such action, subject to Section 12 of this Agreement, or unless it
shall ultimately be determined that Indemnitee is not entitled to be indemnified
by the Company as authorized hereby or thereby. It shall be a defense to any
such action that Indemnitee has not met the standards of conduct which make it
permissible under applicable law or this Agreement for the Company to indemnify
Indemnitee for the amount claimed, but the burden of proving such defense shall
be on the Company and Indemnitee shall be entitled to receive interim payments
of expenses pursuant to Section 2(a) unless and until such defense may be
finally adjudged. It is the parties' intention that if the Indemnitee brings any
such action, the question of Indemnitee's right to indemnification shall
ultimately be for the court to decide, and neither the failure of the Company
(including its Board of Directors, any committee or subgroup of the Board of
Directors, independent legal counsel, or its stockholders) to have made a
determination that indemnification of Indemnitee is proper in the circumstances
because Indemnitee has met the applicable standard of conduct required by
applicable law, nor an actual determination by the Company (including its Board
of Directors, any committee or subgroup of the Board of Directors, independent
legal counsel, or its stockholders) that Indemnitee has not met such applicable
standard of conduct, shall create a presumption that Indemnitee has or has not
met the applicable standard of conduct.

                  (d) Notice to Insurers. If, at the time of the receipt of a
notice of a claim pursuant to Section 2(b) hereof, the Company has director and
officer liability insurance in effect, the Company shall give prompt notice of
the commencement of such proceeding to the insurers in accordance with the
procedures set forth in the respective policies. The Company shall thereafter
take all necessary or desirable action to cause such insurers to pay, on behalf
of the Indemnitee, all amounts payable as a result of such proceeding in
accordance with the terms of such policies.
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                                      -4-

                  (e) Assumption of Defense and Selection of Counsel. In the
event the Company shall be obligated under Section 2(a) hereof to pay the
expenses of any proceeding against Indemnitee, the Company, if appropriate,
shall be entitled to assume the defense of such proceeding, with counsel
approved by Indemnitee, which approval shall not be unreasonably withheld, upon
the delivery to Indemnitee of written notice of its election so to do.
Notwithstanding the foregoing, the Company shall not be permitted to settle any
action or claim on behalf of Indemnitee in any manner which would impose any
unindemnified liability or penalty on the Indemnitee or require any
acknowledgment of wrongdoing on the part of Indemnitee without Indemnitee's
written consent, which consent shall not be unreasonably withheld. After
delivery of such notice, approval of such counsel by Indemnitee and the
retention of such counsel by the Company, and notwithstanding anything to the
contrary contained herein, the Company will not be liable to Indemnitee under
this Agreement for any fees of counsel subsequently incurred by Indemnitee with
respect to the same proceeding, provided that (i) Indemnitee shall have the
right to employ his or her counsel in any such proceeding at Indemnitee's
expense; and (ii) if (A) the employment of separate counsel by Indemnitee has
been previously authorized by the Company, (B) Indemnitee shall have reasonably
concluded that there may be a conflict of interest between the Company and
Indemnitee in the conduct of any such defense, or (C) the Company shall not, in
fact, have employed counsel to assume the defense of such proceeding, then the
fees and expenses of Indemnitee's counsel shall be at the expense of the
Company. The Company shall not be entitled, without the consent of the
Indemnitee, to assume the defense of any claim brought by or in the right of the
Company or as to which counsel for the Indemnitee shall have reasonably made the
conclusion provided for in clause (ii)(B) above.

         3. ADDITIONAL INDEMNIFICATION RIGHTS; NONEXCLUSIVITY.

                  (a) Scope. Notwithstanding any other provision of this
Agreement, the Company hereby agrees to indemnify the Indemnitee to the fullest
extent permitted by the General Corporation Law of the State of Delaware (the
"DGCL"), notwithstanding that such indemnification is not specifically
authorized by the other provisions of this Agreement or the Company's Charter or
By-Laws. In the event of any change, after the date of this Agreement, under the
DGCL which expands the right of a Delaware corporation to indemnify a member of
its board of directors or an officer, such changes shall be, ipso facto, within
the purview of Indemnitee's rights and the Company's obligations under this
Agreement. In the event of any change under the DGCL which narrows the right of
a Delaware corporation to indemnify a member of its Board of Directors or an
officer, such changes, to the extent not otherwise required by such Section or
any successor section shall have no effect on this Agreement or the parties'
rights and obligations hereunder.

                  (b) Nonexclusivity. The indemnification provided by this
Agreement shall not be deemed exclusive of any rights to which Indemnitee may be
entitled under the Company's Charter, its By-Laws, any agreement, any vote of
stockholders or disinterested directors, the DGCL, or otherwise, both as to
action in Indemnitee's official capacity and as to action in another capacity
while holding such office. The indemnification provided under this Agreement
shall continue as to Indemnitee for any action taken or not taken while serving
in an indemnified
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                                      -5-

capacity even though s/he may have ceased to serve in any such capacity at the
time of any action, suit or other covered proceeding.

         4. PARTIAL INDEMNIFICATION. If Indemnitee is entitled under any
provision of this Agreement to indemnification by the Company for some or a
portion of the expenses, judgments, fines or penalties actually or reasonably
incurred by him in the investigation, defense, appeal or settlement of any civil
or criminal action or proceeding, but not, however, for the total amount
thereof, the Company shall nevertheless indemnify Indemnitee for the portion of
such expenses, judgments, fines or penalties to which Indemnitee is entitled.

         5. SEVERABILITY. Nothing in this Agreement is intended to require or
shall be construed as requiring the Company to do or fail to do any act in
violation of applicable law. The Company's inability, pursuant to court order,
to perform its obligations under this Agreement shall not constitute a breach of
this Agreement. The provisions of this Agreement shall be severable as provided
in this Section 5. If this Agreement or any portion hereof shall be invalidated
on any ground by any court of competent jurisdiction, then the Company shall
nevertheless indemnify Indemnitee to the fullest extent permitted by any
applicable portion of this Agreement that shall not have been invalidated, and
the balance of this Agreement not so invalidated shall be enforceable in
accordance with its terms.

         6. OFFICER AND DIRECTOR LIABILITY INSURANCE. The Company shall, from
time to time, make the good faith determination whether or not it is practicable
for the Company to obtain and maintain a policy or policies of insurance with
reputable insurance companies providing the officers and directors of the
Company with coverage for losses from wrongful acts, or to ensure the Company's
performance of its indemnification obligations under this Agreement. Among other
considerations, the Company will weigh the costs of obtaining such insurance
coverage against the protection afforded by such coverage. In all policies of
director and officer liability insurance, Indemnitee shall be named as an
insured in such a manner as to provide Indemnitee the same rights and benefits
as are accorded to the most favorably insured of the Company's directors, if
Indemnitee is a director; or of the Company's officers, if Indemnitee is not a
director of the Company but is an officer; or of the Company's key employees, if
Indemnitee is not an officer or director but is a key employee. Notwithstanding
the foregoing, the Company shall have no obligation to obtain or maintain such
insurance if the Company determines in good faith that such insurance is not
reasonably available, if the premium costs for such insurance are
disproportionate to the amount of coverage provided, if the coverage provided by
such insurance is limited by exclusions so as to provide an insufficient
benefit, or if Indemnitee is covered by similar insurance maintained by a
subsidiary or parent of the Company.

         7. EXCEPTIONS. Any other provision herein to the contrary
notwithstanding, the Company shall not be obligated pursuant to the terms of
this Agreement:

                  (a) To indemnify or advance expenses to Indemnitee with
respect to proceedings or claims initiated or brought voluntarily by Indemnitee
and not by way of defense, except with respect to proceedings brought to
establish or enforce a right to indemnification under this Agreement or any
other statute or law or otherwise as required under Section 145 of the DGCL, but
such indemnification or advancement of expenses may be provided by the
<PAGE>
                                      -6-

Company in specific cases if the Board of Directors has approved the initiation
or bringing of the suit; or

                  (b) To indemnify Indemnitee for any expenses incurred by
Indemnitee with respect to any proceeding instituted by Indemnitee to enforce or
interpret this Agreement, if a court of competent jurisdiction determines that
each of the material assertions made by Indemnitee in such proceeding was not
made in good faith or was frivolous; or

                  (c) To indemnify Indemnitee for expenses or liabilities of any
type whatsoever (including, but not limited to, judgments, fines, ERISA excise
taxes or penalties, and amounts paid in settlement), but such exception shall
only apply to the extent such expenses or liabilities have been paid directly to
Indemnitee by an insurance carrier under a policy of officers' and directors'
liability insurance; or

                  (d) To indemnify Indemnitee for expenses or the payment of
profits arising from the purchase and sale by Indemnitee of securities in
violation of Section 16(b) of the Securities Exchange Act of 1934, as amended,
or any similar successor statute; or

                  (e) To indemnify Indemnitee for any acts, omissions or
transactions from which a director may not be relieved of liability under the
Company's Charter or By-Laws, or from which a court of competent jurisdiction
determines a director may not be relieved of liability under the DGCL.

         8. CONSTRUCTION OF CERTAIN PHRASES

                  (a) For purposes of this Agreement, references to the
"Company" shall include, in addition to the resulting corporation, any
constituent corporation (including any constituent of a constituent) absorbed in
a consolidation or merger which, if its separate existence had continued, would
have had power and authority to indemnify its directors, officers, and employees
or agents, so that if Indemnitee is or was a director, officer, employee or
agent of such constituent corporation, or is or was serving at the request of
such constituent corporation as a director, officer, employee or agent of
another corporation, partnership, joint venture, trust or other enterprise,
Indemnitee shall stand in the same position under the provisions of this
Agreement with respect to the resulting or surviving corporation as Indemnitee
would have with respect to such constituent corporation if its separate
existence had continued.

                  (b) For purposes of this Agreement, references to "other
enterprises" shall include employee benefit plans; references to "fines" shall
include any excise taxes assessed on Indemnitee with respect to an employee
benefit plan; and references to "serving at the request of the Company" shall
include any service as a director, officer, employee or agent of the Company
which imposes duties on, or involves services by, such director, officer,
employee or agent with respect to an employee benefit plan, its participants, or
beneficiaries; and if Indemnitee acted in good faith and in a manner Indemnitee
reasonably believed to be in the interest of the participants and beneficiaries
of an employee benefit plan, Indemnitee shall be deemed to have acted in a
manner "not opposed to the best interests of the Company" as referred to in this
Agreement.
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                                      -7-

         9. EFFECTIVENESS OF AGREEMENT. This Agreement shall be effective as of
the date set forth on the first page and may apply to acts or omissions of
Indemnitee which occurred prior to such date if Indemnitee was an officer,
director, employee or other agent of the Company, or was serving at the request
of the Company as a director, officer, employee or agent of another corporation,
partnership, joint venture, trust or other enterprise, as the time such act or
omission occurred.

         10. NO RIGHTS OF CONTINUED SERVICE. This Agreement shall not impose any
obligation of the Company to continue Indemnitee's service to the Company beyond
any period otherwise required by law or by other agreements or commitments of
the parties, if any.

         11. MISCELLANEOUS.

                  (a) Governing Law. This Agreement and all acts and
transactions pursuant hereto and the rights and obligations of the parties
hereto shall be governed, construed and interpreted in accordance with the laws
of the State of Delaware, without giving effect to principles of conflict of
law.

                  (b) Consent to Jurisdiction. The Company and the Indemnitee
each hereby irrevocably consent to the exclusive jurisdiction of the Court of
Chancery of Delaware for any purpose in connection with any actions or
proceedings which arise out of or relate to this Agreement.

                  (c) Entire Agreement; Enforcement of Rights. This Agreement
sets forth the entire agreement and understanding of the parties relating to the
subject matter herein and merges all prior discussions between them. No
modification of or amendment to this Agreement, nor any waiver of any rights
under this Agreement, shall be effective unless in writing signed by the parties
to this Agreement. The failure by either party to enforce any rights under this
Agreement shall not be construed as a waiver of any rights of such party.

                  (d) Construction. This Agreement is the result of negotiations
between, and has been reviewed by, each of the parties hereto and their
respective counsel, if any; accordingly, this Agreement shall be deemed to be
the product of all of the parties hereto, and no ambiguity shall be construed in
favor of or against any one of the parties hereto.

                  (e) Notices. Unless otherwise provided in this Agreement, any
notice, demand or request required or permitted to be given under this Agreement
shall be in writing and shall be deemed sufficient when directed to the Chief
Executive Officer of the Company at the address shown on the signature page of
this Agreement (or such other address as the Company shall designate in writing)
and when delivered personally or three business days after being postmarked, as
certified or registered mail, with postage prepaid, and addressed to the party
to be notified at such party's address as set forth below or as subsequently
modified by written notice.
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                                      -8-

                  (f) Counterparts. This Agreement may be executed in two or
more counterparts, each of which shall be deemed an original and all of which
together shall constitute one instrument.

                  (g) Successors And Assigns. This Agreement shall be binding
upon the Company and its successors and assigns and shall inure to the benefit
of Indemnitee and Indemnitee's heirs, legal representatives, executives and
administrators.

                  (h) Subrogation. In the event of payment under this Agreement,
the Company shall be subrogated to the extent of such payment to all of the
rights of recovery of Indemnitee, who shall execute all documents required and
shall do all acts that may be necessary to secure such rights and to enable the
Company to effectively bring suit to enforce such rights.

                  (i) Term. All agreements and obligations of the Company
contained herein shall continue during the period that the Indemnitee is a
director, officer or agent of the Company and shall continue thereafter so long
as Indemnitee shall be subject to any possible claim or threatened, pending or
completed action, suit or proceeding, whether civil, criminal, administrative or
investigative, by reason of the fact that Indemnitee was serving in the capacity
referred to herein.

         12. ATTORNEYS' FEES. In the event that any action is instituted by
Indemnitee under this Agreement to enforce or interpret any of the terms hereof,
and in the event Indemnitee is ultimately successful in such action, Indemnitee
shall be entitled to be paid all court costs and expenses, including reasonable
attorneys' fees, actually and reasonably incurred by Indemnitee with respect to
such action. In the event of an action instituted by or in the name of the
Company under this Agreement or to enforce or interpret any of the terms of this
Agreement, Indemnitee shall be entitled to be paid all court costs and expenses,
including reasonable attorneys' fees, actually and reasonably incurred by
Indemnitee in defense of such action (including with respect to Indemnitee's
counterclaims and cross-claims made in such action), unless the Company is
ultimately successful in such action.

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                                      -9-

         IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the date first above written.

ACUSPHERE, INC.

By: ________________________________            __________________________

Name: ______________________________            Indemnitee

Title: _____________________________

Address:  Acusphere, Inc.                       Address: _________________
          500 Arsenal Street
          Watertown, MA  02472                           _________________
          (617) 648-8800 (phone)
          (617) 926-4750 (fax)                           _________________
<PAGE>
Exhibit 1
UNDERTAKING

         1. This Undertaking is submitted pursuant to the Indemnification
Agreement dated as of ________________ between Acusphere, Inc., a Delaware
corporation (the "Company"), and the undersigned (the "Agreement"). Capitalized
terms used but not defined herein shall have the respective meanings set forth
in the Agreement.

         2. I am requesting certain Expense Advances in connection with a Claim.

         3. I hereby undertake to repay such Expense Advances if it shall
ultimately be determined that I am not entitled to be indemnified by the Company
therefor under the Agreement or otherwise.

         4. The Expense Advances are, in general, all related to:

                          Signed: _____________________________

                          Dated: ______________________________<PAGE>

                                                                   Exhibit 10.29

THIS WARRANT AND THE SECURITIES THAT MAY BE ACQUIRED UPON EXERCISE OF THE
WARRANT HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED.
NEITHER THIS WARRANT NOR THE SECURITIES THAT MAY BE ACQUIRED UPON EXERCISE OF
THIS WARRANT MAY BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE
ABSENCE OF A REGISTRATION STATEMENT IN EFFECT UNDER SUCH ACT OR AN OPINION OF
COUNSEL SATISFACTORY TO ACUSPHERE THAT SUCH REGISTRATION IS NOT REQUIRED OR
UNLESS SOLD PURSUANT TO RULE 144 OR RULE 144A OF SUCH ACT.

THIS WARRANT AND THE SECURITIES THAT MAY BE ACQUIRED UPON EXERCISE OF THE
WARRANT ARE SUBJECT TO A CONVERTIBLE NOTE AND WARRANT PURCHASE AND SECURITIES
EXCHANGE AGREEMENT, DATED AS OF _________, 2003, AS AMENDED AND IN EFFECT FROM
TIME TO TIME, A COPY OF WHICH IS ON FILE AT THE PRINCIPAL PLACE OF BUSINESS OF
ACUSPHERE.

THIS WARRANT AND THE SECURITIES THAT MAY BE ACQUIRED UPON EXERCISE OF THE
WARRANT ARE SUBJECT TO A VOTING AGREEMENT (A COPY OF WHICH MAY BE OBTAINED FROM
ACUSPHERE), AS AMENDED FROM TIME TO TIME, AND BY ACCEPTING ANY INTEREST IN THIS
WARRANT OR SUCH SECURITIES THE PERSON ACCEPTING SUCH INTEREST SHALL BE DEEMED TO
AGREE TO AND SHALL BECOME BOUND BY ALL THE PROVISIONS OF SUCH VOTING AGREEMENT.

                                 ACUSPHERE, INC.

                                WARRANT AGREEMENT

                Exercise Amount: $ [20% of note principal amount]

Warrant No. ____                                                 _________, 2003

         ACUSPHERE, INC., a Delaware corporation (the "Company"), hereby
certifies that, for value received, [NAME] (hereinafter referred to as "Holder")
is entitled, subject to the terms and conditions set forth below, to purchase
from the Company the Warrant Number (as defined in Section 1.3 below) of fully
paid and non-assessable shares of the Warrant Class (as defined in Section 1.2
below), at a price per share equal to the Exercise Price (as defined in Section
1.2 below). The shares issuable upon exercise of this Warrant are hereinafter
referred to as the "Shares" and are subject to adjustment as hereinafter
provided.

         This Warrant is one of a series of warrants of like tenor
(collectively, the "Warrants" and each a "Warrant") issued by the Company
pursuant to and entitled to the benefits of that certain Convertible Promissory
Note and Warrant Purchase Agreement, dated as of _________, 2003, by and among
the Company and the several Investors listed in Exhibit A thereto (collectively,
the "Holders" and each a "Holder") (as the same may be amended from time to
time, the "Purchase Agreement"), and each Holder of this Warrant, by such
Holder's acceptance hereof, agrees to be bound by the provisions of the Purchase
Agreement, including without limitation the
<PAGE>
                                      -2-

amendment, waiver and exercise of remedies provisions set forth in Section 6.9
therein. This Warrant is being issued in conjunction with the issuance of one of
a series of 10% convertible promissory notes (collectively, the "Notes" and each
a "Notes") pursuant to the Purchase Agreement. Capitalized terms used herein but
not defined herein shall have the meanings ascribed to them in the Purchase
Agreement.

ARTICLE 1. EXERCISE.

         1.1 Method of Exercise. The Holder may exercise this Warrant in whole
or in part by delivering this Warrant together with a duly executed Notice of
Exercise in substantially the form attached as Appendix 1 hereto to the
principal office of the Company. Unless the Holder is exercising the conversion
right set forth in Section 1.4, the Holder shall also deliver to the Company
payment in full, in lawful money of the United States, for the aggregate
Exercise Price for the Shares being purchased. Any exercise of this Warrant in
connection with a Change of Control or an initial public offering of the
Company's equity securities may be conditioned upon the actual consummation of
such Change of Control or initial public offering.

         1.2 Warrant Class and Exercise Price.

                  (a) Upon the consummation of the earlier to occur of a Next
Equity Financing (as defined in the Notes), or a Negotiated Conversion (as
defined in the Notes), if any, "Warrant Class" shall mean shares of the same
class and series as the equity securities into which the Notes are automatically
converted in connection therewith, and "Exercise Price" shall mean an amount
equal to the conversion price per share at which such Notes are so converted.

                  (b) Prior to the consummation of the earlier to occur of a
Next Equity Financing or Negotiated Conversion, "Warrant Class" shall mean
shares of the Company's Series J-2 Convertible Preferred Stock, $.01 par value
per share (the "Series J-2 Preferred Stock"), and "Exercise Price" shall mean an
amount equal to the Original Series J Issue Price (as defined in the Company's
Twelfth Amended and Restated Certificate of Incorporation (as amended and in
effect from time to time, the "Charter")); provided, however, that, immediately
prior to the consummation of a Change of Control (as defined in the Company's
Charter), in connection with which the aggregate consideration to be paid or
payable to the Company and/or its stockholders is less than the sum of the
aggregate cumulative liquidation preference of the Company's preferred stock
then outstanding (excluding any shares of preferred stock issued or issuable
upon exercise of the Warrants), plus the aggregate principal amount outstanding
under all Notes then outstanding and all accrued and unpaid interest thereon,
"Exercise Price" shall mean an amount equal to 80% of the Original Series J
Issue Price. If the consideration received by the Company and/or its
stockholders in connection with such Change of Control is other than cash, its
value will be deemed to be its fair market value, as determined by the Company
and the Holders of Warrants representing at least a majority of the aggregate
Exercise Amount under all Warrants then outstanding (a "Warrant Majority") in a
manner reasonably consistent with Section 2.10(b) and Section 8 of ARTICLE
FOURTH of the Charter, or in such manner as the Company and such Holders of a
Warrant Majority may otherwise agree.

                  1.3 Warrant Number. The Warrant Number shall be determined as
follows:

                           N = A/E
<PAGE>
                                      -3-

                  Where:

                     N = The maximum number of shares of stock of the
                         Warrant Class that may be purchased upon exercise of
                         this Warrant.

                     A = The Exercise Amount

                     E = The Exercise Price

         1.4 Net Issue Exercise. In lieu of exercising this Warrant as specified
in Section 1.1, the Holder may convert this Warrant from time to time, in whole
or in part, without payment of any consideration, into a number of Shares
determined as follows:

                     X = Y(A-B)/A

                  Where:

                     X = The number of Shares to be issued to the Holder.

                     Y = The number of Shares with respect to which this Warrant
                         is being exercised.

                     A = The Fair Market Value of one Share.

                     B = The Exercise Price.

         1.5 Fair Market Value. The fair market value of a Share shall be
determined by the Company and the Holders of a Warrant Majority in a manner
reasonably consistent with Section 2.10(b) and Section 8 of ARTICLE FOURTH of
the Charter, or in such manner as the Company and such Holders of a Warrant
Majority may otherwise agree.

         1.6. Partial Exercise. This Warrant may be exercised in part, and the
Holder shall be entitled to receive a new warrant, which shall be dated as of
the date of this Warrant, covering the number of Shares in respect of which this
Warrant shall not have been exercised.

         1.7. Fractional Shares. No fractional Shares shall be issuable upon
exercise or conversion of the Warrant and the number of Shares to be issued
shall be rounded down to the nearest whole Share. In lieu of such fractional
shares, the Company will pay the cash value of such fraction.

         1.8. Issuance Date. The person or persons in whose name or names any
certificate representing Shares is issued hereunder shall be deemed to have
become the holder of record of the Shares represented thereby as at the close of
business on the date this Warrant is exercised with respect to such shares,
whether or not the transfer books of the Company shall be closed.

         1.9. Expiration Date. This Warrant shall expire and be void thereafter
upon the earliest to occur of (a) the consummation of an initial public offering
of the Company's equity securities in which the underwriters advise the Holders
in writing that marketing factors require
<PAGE>
                                      -4-

that no warrants remain outstanding following the consummation of the initial
public offering, (b) the consummation of a Change of Control or (c) _________,
2008.

ARTICLE 2. ADJUSTMENTS TO THE SHARES.

         2.1 Stock Dividends, Splits, Etc. If the Company declares or pays a
dividend on the outstanding shares of the Warrant Class, payable in shares of
the Warrant Class, or other securities, or subdivides the outstanding Warrant
Class into a greater number of shares of the Warrant Class, then upon exercise
of this Warrant, for each Share acquired, Holder shall receive, without
additional cost to Holder, the total number and kind of securities to which
Holder would have been entitled had Holder owned the Shares of record as of the
date the dividend or subdivision occurred.

         2.2 Reclassification, Merger, Exchange or Substitution. Upon any
reclassification, exchange, substitution, merger, consolidation, reorganization
or other event that results in a change of the number and/or class of the
securities issuable upon exercise or conversion of this Warrant, Holder shall be
entitled to receive, upon exercise or conversion of this Warrant, the number and
kind of securities and property that Holder would have received for the Shares
if this Warrant had been exercised immediately before such reclassification,
exchange, substitution, merger, consolidation, reorganization or other event.
The Company or its successor shall promptly issue to Holder a new warrant of
like tenor for such new securities or other property. The new warrant shall
provide for adjustments which shall be as nearly equivalent as may be
practicable to the adjustments provided for in this Article 2 including, without
limitation, adjustments to the Exercise Price and to the number of securities or
property issuable upon exercise of the new warrant. The provisions of this
Section 2.2 shall similarly apply to successive reclassifications, exchanges,
substitutions, mergers, consolidations, reorganizations or other events.

         2.3 Adjustments for Combinations, Etc. If the outstanding shares of the
Warrant Class are combined or consolidated, by reclassification or otherwise,
into a lesser number of shares, the Exercise Price shall be proportionately
increased and the number of Shares issuable upon exercise or conversion of this
Warrant shall be proportionately decreased.

         2.4 No Impairment. The Company shall not, by amendment of the
Certificate or its by-laws or through a reorganization, transfer of assets,
consolidation, merger, dissolution, issue, or sale of securities or any other
voluntary action, avoid or seek to avoid the observance or performance of any of
the terms to be observed or performed under this Warrant by the Company, but
shall at all times in good faith assist in carrying out of all the provisions of
this Article 2 and in taking all such action as may be necessary or appropriate
to protect Holder's rights under this Article 2 against impairment.

         2.5 Certificate as to Adjustments. Upon each adjustment of the Exercise
Price, number or class of Shares or other securities for which the Shares are
convertible or exchangeable, the Company at its expense shall promptly compute
such adjustment, and furnish Holder with a certificate of its chief financial
officer setting forth such adjustment and the facts upon which such adjustment
is based. The Company shall at any time and from time to time, upon written
request, furnish Holder with a certificate setting forth the Exercise Price,
number and class of Shares and conversion ratio in effect upon the date thereof
and the series of adjustments leading to such Exercise Price, number and class
of Shares and conversion ratio.
<PAGE>
                                      -5-

ARTICLE 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY.

         3.1 Representations and Warranties. The Company hereby represents and
warrants to, and agrees with, the Holder as follows:

                  (a) All Shares which may be issued upon the due exercise of
this Warrant, and all Common Stock or other securities, if any, issuable upon
due conversion of the Shares, shall, upon issuance, be duly authorized, validly
issued, fully paid and non-assessable, and free of any liens and encumbrances
except for restrictions on transfer provided for herein, any other agreement to
which the Company is a party, or under applicable federal and state securities
laws.

                  (b) The Company covenants that at such time as the Warrant
Class is determined, it shall promptly take all necessary corporate actions to
authorize and reserve and keep available out of its authorized and unissued
shares such number of shares of the Warrant Class, Common Stock and other
securities as will be sufficient to permit the exercise in full of this Warrant
and the conversion of the Shares into shares of Common Stock or such other
securities.

         3.2 Notice of Certain Events. In the event of (a) any taking by the
Company of a record of the holders of any class of securities for the purpose of
determining the holders thereof who are entitled to receive any dividend or
other distribution, (b) an initial public offering of the Company's equity
securities in which the underwriters advise the Holders in writing that
marketing factors require that no warrants remain outstanding following the
consummation of the initial public offering, (c) any reclassification of the
capital stock of the Company, capital reorganization of the Company,
consolidation or merger involving the Company, or sale or conveyance of all or
substantially all of its assets, or any Change of Control, or (c) any voluntary
or involuntary dissolution, liquidation or winding-up of the Company, then and
in each such event the Company will mail or cause to be mailed to the Holder a
notice specifying (i) the date on which any such record is to be taken for the
purpose of such dividend, distribution or right, and stating the amount and
character of such dividend, distribution or right, or (ii) the date on which any
such initial public offering, reclassification, reorganization, consolidation,
merger, sale or conveyance, Change of Control, dissolution, liquidation or
winding-up is to take place, and the time, if any is to be fixed, as of which
the holders of record in respect of such event are to be determined. Such notice
shall be mailed as soon as practicable, but in any event no less than ten (10)
days prior to the date specified in such notice on which any such action is to
be taken.

ARTICLE 4. MISCELLANEOUS.

         4.1. No Rights as Shareholder. This Warrant shall not entitle the
Holder to any of the rights of a shareholder of the Company except upon exercise
in accordance with the terms hereof.

         4.2. Legends. The Shares (and the securities issuable, directly or
indirectly, upon conversion of the Shares, if any) shall be imprinted with a
legend in substantially the following form:
<PAGE>
                                      -6-

         "THESE SHARES AND THE SECURITIES THAT MAY BE ACQUIRED UPON CONVERSION
         OF THESE SHARES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
         1933, AS AMENDED. NEITHER THESE SHARES NOR THE SECURITIES THAT MAY BE
         ACQUIRED UPON CONVERSION OF THESE SHARES MAY BE SOLD, OFFERED FOR SALE,
         PLEDGED OR HYPOTHECATED IN THE ABSENCE OF A REGISTRATION STATEMENT IN
         EFFECT UNDER SUCH ACT OR AN OPINION OF COUNSEL SATISFACTORY TO
         ACUSPHERE THAT SUCH REGISTRATION IS NOT REQUIRED OR UNLESS SOLD
         PURSUANT TO RULE 144 OR RULE 144A OF SUCH ACT.

         THESE SHARES AND THE SECURITIES THAT MAY BE ACQUIRED UPON CONVERSION OF
         THESE SHARES ARE SUBJECT TO A CONVERTIBLE NOTE AND WARRANT PURCHASE AND
         SECURITIES EXCHANGE AGREEMENT, DATED AS OF __________, 2003, AS AMENDED
         AND IN EFFECT FROM TIME TO TIME, A COPY OF WHICH IS ON FILE AT THE
         PRINCIPAL PLACE OF BUSINESS OF ACUSPHERE.

         THESE SHARES AND THE SECURITIES THAT MAY BE ACQUIRED UPON CONVERSION OF
         THESE SHARES ARE SUBJECT TO A VOTING AGREEMENT (A COPY OF WHICH MAY BE
         OBTAINED FROM ACUSPHERE), AS AMENDED FROM TIME TO TIME, AND BY
         ACCEPTING ANY INTEREST IN THESE SHARES OR SUCH SECURITIES THE PERSON
         ACCEPTING SUCH INTEREST SHALL BE DEEMED TO AGREE TO AND SHALL BECOME
         BOUND BY ALL THE PROVISIONS OF SUCH VOTING AGREEMENT."

         4.3. Waiver by Holder. No waiver of any obligation of the Company under
this Warrant shall be effective unless it is in a writing signed in accordance
with the amendment, waiver and exercise of remedies provisions set forth in
Section 6.9 of the Purchase Agreement. A waiver by the Holder of, or delay or
omission on the part of the Holder in exercising, any right or remedy under this
Warrant on any occasion shall not be a bar to exercise of the same right or
remedy on any subsequent occasion or of any other right or remedy at any time.

         4.4. Notice. Any notice required or permitted under this Warrant shall
be given in the manner set forth in the Purchase Agreement.

         4.5. Severability. In the event any one or more of the provisions of
this Warrant shall for any reason be held to be invalid, illegal or
unenforceable, in whole or in part or in any respect, or in the event that any
one or more of the provisions of this Warrant operate or would prospectively
operate to invalidate this Warrant, then and in any such event, such
provision(s) only shall be deemed null and void and shall not affect any other
provision of this Warrant and the remaining provisions of this Warrant shall
remain operative and in full force and effect and in no way shall be affected,
prejudiced, or disturbed thereby.

         4.6. Governing Law. This Warrant shall be governed by and construed in
accordance with the laws of the Commonwealth of Massachusetts.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]
<PAGE>
                                      -7-

         IN WITNESS WHEREOF, the Company has caused this Warrant to be executed
as an instrument under seal by its duly authorized representative as of the date
first above written.

Dated:  April  __, 2003               ACUSPHERE, INC.

(Corporate Seal)                      By: _______________________________
                                      Name: _____________________________
Attest:                               Title: ____________________________

____________________________
<PAGE>
                                                                      APPENDIX 1

                                 ACUSPHERE, INC.

                               NOTICE OF EXERCISE

         1. The undersigned hereby elects to purchase _____ Warrant Shares
pursuant to Section 1.1 of the attached Warrant, and tenders herewith payment of
the Exercise Price of such shares in full.

         1. The undersigned hereby elects to convert the attached Warrant into
Shares in the manner specified in Section 1.4 of the attached Warrant. This
conversion is exercised with respect to _______________ Warrant Shares.

         [Strike paragraph that does not apply.]

         2. Please issue a certificate or certificates representing said shares
in the name of the undersigned or in such other name as is specified below:

                _________________________________
                (Name)
                _________________________________

                _________________________________
                (Address)

         3. The undersigned represents it is acquiring the shares solely for its
own account and not as a nominee for any other party and not with a view toward
the resale or distribution thereof except in compliance with applicable
securities laws.

                                         ____________________________
                                         (Signature)

                                         ____________________________
                                         (Date)
<PAGE>
                           SCHEDULE OF WARRANTHOLDERS

<TABLE>
<CAPTION>
INVESTOR:                                                                       NUMBER OF SHARES ISSUABLE UPON EXERCISE OF WARRANTS:
<S>                                                                             <C>
Thomas Weisel Capital Partners, L.P.                                                             854,703

TWP CEO Founders' Circle (AI), L.P.                                                               19,747

TWP CEO Founders' Circle (QP), L.P.                                                               72,146

Thomas Weisel Capital Partners (Dutch), L.P.                                                      19,996

Thomas Weisel Capital Partners (Dutch II), L.P.                                                   19,996

Thomas Weisel Capital Partners Employee Fund, L.P.                                                 6,792

MVI Medical Venture Investments Limited                                                          203,662

Diamond Capital Management Inc. (as Investment Advisor for the Retirement                        141,377

Program Plan for Employees of Union Carbide Corporation and its Participating

Subsidiary Companies)

Alta V Limited Partnership                                                                       241,175

Customs House Partners                                                                             2,534

Polaris Venture Partners, L.P.                                                                   209,105

Polaris Venture Partners Founders' Fund, L.P.                                                     12,510

Audax Private Equity Fund, L.P.                                                                  164,449

Audax Co-Invest, L.P.                                                                             13,771

Audax Trust Co-Invest, L.P.                                                                           33

BancBoston Ventures, Inc.                                                                        151,743

Private Equity Portfolio Fund II, LLC                                                             57,613

Bank of America Ventures                                                                         370,871

BA Venture Partners II                                                                            41,208

Technology Funding Partners III, L.P.                                                             84,229

Technology Fund Venture Partners V, an Aggressive Growth Fund, L.P.                               53,885

DeBar Investment Partnership LLP                                                                   3,394

Dintersmith Family Partnership                                                                     1,656

Robert S. Langer                                                                                   2,898

David Norman                                                                                       8,003

TOTAL:                                                                                         2,757,495
</TABLE>

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