EXHIBIT 10.22

AMENDED AND RESTATED

INSMED INCORPORATED

2000 EMPLOYEE STOCK PURCHASE PLAN

The purpose of the Amended and Restated Insmed Incorporated 2000 Employee Stock
Purchase Plan (the “Plan”) is to provide eligible employees of Insmed
Incorporated (the “Company”) and certain of its subsidiaries with opportunities
to purchase shares of the Company’s common stock, par value $0.01 per share (the
“Common Stock”). Subject to Section 17, One Million Five Hundred Thousand
(1,500,000) shares of Common Stock in the aggregate have been approved and
reserved for this purpose. The Plan is intended to constitute an “employee stock
purchase plan” within the meaning of Section 423(b) of the Internal Revenue Code
of 1986, as amended (the “Code”), and shall be interpreted in accordance with
that intent.

1. Administration. The Plan will be administered by the Compensation Committee
of the Board or Directors of the Company or such other person or persons
appointed by the Company’s Board of Directors (the “Board”) for such purpose
(the “Administrator”). The Administrator has authority to make rules and
regulations for the administration of the Plan, and its interpretations and
decisions with regard thereto shall be final and conclusive. No member of the
Board or individual exercising administrative authority with respect to the Plan
shall be liable for any action or determination made in good faith with respect
to the Plan or any option granted hereunder.

2. Offerings. The Company will make one or more offerings to eligible employees
to purchase Common Stock under the Plan (“Offerings”). Unless otherwise
determined by the Administrator, each Offering will begin on the first business
day occurring on or after each January 1 and July 1 and will end on the last
business day occurring on or before the following

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June 30 and December 31, respectively. The Administrator may, in its discretion,
designate a different period for any Offering, provided that no Offering shall
exceed six months in duration or overlap any other Offering.

3. Eligibility. All employees of the Company (including employees who are also
directors of the Company) and all employees of each Designated Subsidiary (as
defined in Section 11) are eligible to participate in any one or more of the
Offerings under the Plan, provided that as of the first day of the applicable
Offering (the “Offering Date”) they are customarily employed by the Company or a
Designated Subsidiary for more than 20 hours a week.

4. Participation. An employee eligible on any Offering Date may participate in
such Offering by submitting an enrollment form to such eligible employee’s
appropriate payroll location at least 15 business days before the Offering Date
(or by such other deadline as shall be established for the Offering). The form
will (a) state a whole percentage to be deducted from such eligible employee’s
Compensation (as defined in Section 11) per pay period, (b) authorize the
purchase of Common Stock for such eligible employee in each Offering in
accordance with the terms of the Plan and (c) specify the exact name or names in
which shares of Common Stock purchased for such eligible employee are to be
issued pursuant to Section 10. An eligible employee who does not enroll in
accordance with these procedures will be deemed to have waived his right to
participate. Unless an eligible employee files a new enrollment form or
withdraws from the Plan, such eligible employee’s deductions and purchases will
continue at the same percentage of Compensation for future Offerings, provided
such eligible employee remains eligible to participate hereunder.
Notwithstanding the foregoing, participation in the Plan will neither be
permitted nor be denied contrary to the requirements of the Code.

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5. Employee Contributions. Each eligible employee may authorize payroll
deductions at a minimum of one percent (1%) up to a maximum of fifteen percent
(15%) of such eligible employee’s Compensation for each pay period. The Company
will maintain book accounts showing the amount of payroll deductions made by
each participating employee for each Offering. No interest will accrue or be
paid on payroll deductions.

6. Deduction Changes. Except as may be determined by the Administrator in
advance of an Offering, a participating employee may not increase or decrease
such employee’s payroll deduction during any Offering, but may increase or
decrease such employee’s payroll deduction with respect to the next Offering
(subject to the limitations of Section 5) by filing a new enrollment form at
least 15 business days before the next Offering Date (or by such other deadline
as shall be established for the Offering). The Administrator may, in advance of
any Offering, establish rules permitting an employee to increase, decrease or
terminate his payroll deduction during an Offering.

7. Withdrawal. A participating employee may withdraw from participation in the
Plan by delivering a written notice of withdrawal to such eligible employee’s
appropriate payroll location. The employee’s withdrawal will be effective as of
the next business day. Following an employee’s withdrawal, the Company will
promptly refund to him his entire account balance under the Plan (after payment
for any Common Stock purchased before the effective date of withdrawal). Partial
withdrawals are not permitted. The employee may not begin participation again
during the remainder of the Offering, but may enroll in a subsequent Offering in
accordance with Section 4.

8. Grant of Options. On each Offering Date, the Company will grant to each
eligible employee who is then a participant in the Plan an option (“Option”) to
purchase on the last day

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of such Offering (the “Exercise Date”), at the Option Price hereinafter provided
for, (a) a number of shares of Common Stock determined by dividing such
employee’s accumulated payroll deductions on such Exercise Date by the lower of
(i) 85% of the Fair Market Value of the Common Stock on the Offering Date, or
(ii) 85% of the Fair Market Value of the Common Stock on the Exercise Date, or
(b) such other lesser maximum number of shares as shall have been established by
the Administrator in advance of the Offering; provided, however, that such
Option shall be subject to the limitations set forth below. Each employee’s
Option shall be exercisable only to the extent of such employee’s accumulated
payroll deductions on the Exercise Date. The purchase price for each share
purchased under each Option (the “Option Price”) will be 85% of the Fair Market
Value of the Common Stock on the Offering Date or the Exercise Date, whichever
is less.

Notwithstanding the foregoing, no employee may be granted an option hereunder if
such employee, immediately after the option was granted, would be treated as
owning stock possessing five percent (5%) or more of the total combined voting
power or value of all classes of stock of the Company or any Parent or
Subsidiary (as defined in Section 11). For purposes of the preceding sentence,
the attribution rules of Section 424(d) of the Code shall apply in determining
the stock ownership of an employee, and all stock which the employee has a
contractual right to purchase shall be treated as stock owned by the employee.
In addition, no employee may be granted an Option which permits his rights to
purchase stock under the Plan, and any other employee stock purchase plan of the
Company and its Parents and Subsidiaries, to accrue at a rate which exceeds
$25,000 of the fair market value of such stock (determined on the option grant
date or dates) for each calendar year in which the Option is outstanding at any
time. The purpose of the limitation in the preceding sentence is to comply with
Section 423(b)(8) of the Code and shall be applied taking Options into account
in the order in which they were granted.

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9. Exercise of Option and Purchase of Shares. Each employee who continues to be
a participant in the Plan on the Exercise Date shall be deemed to have exercised
such employee’s Option on such date and shall acquire from the Company such
number of whole shares of Common Stock reserved for the purpose of the Plan as
such employee’s accumulated payroll deductions on such date will purchase at the
Option Price, subject to any other limitations contained in the Plan. Any amount
remaining in an employee’s account at the end of an Offering solely by reason of
the inability to purchase a fractional share will be carried forward to the next
Offering; any other balance remaining in an employee’s account at the end of an
Offering will be refunded to the employee promptly without interest.

10. Issuance of Certificates. Certificates or a book entry with the Company’s
transfer agent representing shares of Common Stock purchased under the Plan may
be issued only in the name of the employee, in the name of the employee and
another person of legal age as joint tenants with rights of survivorship, or in
the name of a broker authorized by the employee to be his, or their, nominee for
such purpose.

11. Definitions.

The term “Compensation” means the amount of total cash compensation, prior to
salary reduction pursuant to Sections 125, 132(f) or 401(k) of the Code,
including base pay, overtime, commissions, and incentive or bonus awards, but
excluding allowances and reimbursements for expenses such as relocation
allowances or travel expenses, income or gains on the exercise of Company stock
options, and similar items.

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The term “Designated Subsidiary” means any present or future Subsidiary (as
defined below) that has been designated by the Board to participate in the Plan.
The Board may so designate any Subsidiary, or revoke any such designation, at
any time and from time to time, either before or after the Plan is approved by
the stockholders.

The term “Fair Market Value of the Common Stock” on any given date means the
fair market value of the Common Stock determined in good faith by the
Administrator; provided, however, that if the Common Stock is admitted to
quotation on the National Association of Securities Dealers Automated Quotation
System (“NASDAQ”), the NASDAQ Stock Market LLC or national securities exchange,
the determination shall be made by reference to market quotations. If there are
no market quotations for such date, the determination shall be made by reference
to the last date preceding such date for which there are market quotations.

The term “Parent” means a “parent corporation” with respect to the Company, as
defined in Section 424(e) of the Code.

The term “Subsidiary” means a “subsidiary corporation” with respect to the
Company, as defined in Section 424(f) of the Code.

12. Rights on Termination of Employment. If a participating employee’s
employment terminates for any reason before the Exercise Date for any Offering,
no payroll deduction will be taken from any pay due and owing to the employee
and the balance in such employee’s account will be paid to such employee or, in
the case of such employee’s death, to such employee’s designated beneficiary as
if such employee had withdrawn from the Plan under Section 7. An employee will
be deemed to have terminated employment, for this purpose, if such employee’s
employer, having been a Designated Subsidiary, ceases to be a Subsidiary, or if
the employee is transferred to any entity other than the Company or a Designated
Subsidiary.

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An employee will not be deemed to have terminated employment, for this purpose,
if the employee is on an approved leave of absence for military service or
sickness, or for any other purpose approved by the Company, if the employee’s
right to reemployment is guaranteed either by a statute or by contract or under
the policy pursuant to which the leave of absence was granted or if the
Administrator otherwise provides in writing.

13. Special Rules. Notwithstanding anything herein to the contrary, the
Administrator may adopt special rules applicable to the employees of a
particular Designated Subsidiary, whenever the Administrator determines that
such rules are necessary or appropriate for the implementation of the Plan in a
jurisdiction where such Designated Subsidiary has employees; provided that such
rules are consistent with the requirements of Section 423(b) of the Code. Such
special rules may include (by way of example, but not by way of limitation) the
establishment of a method for employees of a given Designated Subsidiary to fund
the purchase of shares other than by payroll deduction, if the payroll deduction
method is prohibited by local law or is otherwise impracticable. Any special
rules established pursuant to this Section 13 shall, to the extent possible,
result in the employees subject to such rules having substantially the same
rights as other participants in the Plan.

14. Optionees Not Stockholders. Neither the granting of an Option to an employee
nor the deductions from such employee’s pay shall constitute such employee a
holder of the shares of Common Stock covered by an Option under the Plan until
such shares have been purchased by and issued to such employee.

15. Rights Not Transferable. Rights under the Plan are not transferable by a
participating employee other than by will or the laws of descent and
distribution, and are exercisable during the employee’s lifetime only by the
employee.

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16. Application of Funds. All funds received or held by the Company under the
Plan may be combined with other corporate funds and may be used for any
corporate purpose.

17. Adjustment in Case of Changes Affecting Common Stock. Notwithstanding
anything to the contrary set forth herein, in the event of a subdivision of
outstanding shares of Common Stock, or the payment of a dividend in Common
Stock, the number of shares approved for the Plan, and the share limitation set
forth in Section 8, shall be increased proportionately, and such other
adjustment shall be made as may be deemed equitable by the Administrator. In the
event of any other change affecting the Common Stock, such adjustment shall be
made as may be deemed equitable by the Administrator to give proper effect to
such event.

18. Amendment of the Plan. The Board may at any time, and from time to time,
amend the Plan in any respect, except that without the approval, within 12
months of such Board action, by the stockholders, no amendment shall be made
increasing the number of shares approved for the Plan or making any other change
that would require stockholder approval in order for the Plan, as amended, to
qualify as an “employee stock purchase plan” under Section 423(b) of the Code.

19. Insufficient Shares. If the total number of shares of Common Stock that
would otherwise be purchased on any Exercise Date plus the number of shares
purchased under previous Offerings under the Plan exceeds the maximum number of
shares issuable under the Plan, the shares then available shall be apportioned
among participants in proportion to the amount of payroll deductions accumulated
on behalf of each participant that would otherwise be used to purchase Common
Stock on such Exercise Date.

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20. Termination of the Plan. The Plan may be terminated at any time by the
Board. Upon termination of the Plan, all amounts in the accounts of
participating employees shall be promptly refunded without interest.

21. Governmental Regulations. The Company’s obligation to sell and deliver
Common Stock under the Plan is subject to obtaining all governmental approvals
required in connection with the authorization, issuance, or sale of such stock.

The Plan shall be governed by Virginia law except to the extent that such law is
preempted by federal law.

22. Issuance of Shares. Shares may be issued upon exercise of an Option from
authorized but unissued Common Stock, from shares held in the treasury of the
Company, or from any other proper source.

23. Tax Withholding. Participation in the Plan is subject to any minimum
required tax withholding on income of the participant in connection with the
Plan. Each employee agrees, by entering the Plan, that the Company and its
Subsidiaries shall have the right to deduct any such taxes from any payment of
any kind otherwise due to the employee, including shares issuable under the
Plan.

24. Notification Upon Sale of Shares. Each employee agrees, by entering the
Plan, to give the Company prompt notice of any disposition of shares purchased
under the Plan where such disposition occurs within two (2) years after the date
of grant of the Option pursuant to which such shares were purchased.

25. Effective Date and Approval of Shareholders. The Plan shall take effect on
the later of the date it is adopted by the Board and the date it is approved by
the holders of a majority of the votes cast at a meeting of stockholders at
which a quorum is present or by written consent of the stockholders.