POWER OF ATTORNEY

     KNOW ALL BY THESE PRESENTS, that the undersigned hereby authorizes Jeffrey
S. Hackman, Jeffrey L. Quillen, Ryan M. Rourke Reed and Stacie S. Aarestad,
each acting singly, to execute and caused to be filed with the United States
Securities and Exchange Commission any and all documents or filings, including
any amendments thereto, required to be so filed. The undersigned hereby grants
to the attorney-in-fact full power and authority to do and perform any and
every act and thing whatsoever requisite, necessary or proper to be done in the
exercise of any of the rights and powers herein granted, as fully to all
intents and purposes as the undersigned might or could do personally present,
with full power of substitution, resubstitution or revocation, hereby ratifying
and confirming all that such attorney-in-fact, or such attorney's-in-fact
substitute or substitutes, shall lawfully do or cause to be done by virtue of
this power of attorney and the rights and powers herein granted. The
undersigned acknowledges that the foregoing attorney-in-fact, in serving in
such capacity at the request of the undersigned, is not assuming any of the
undersigned's responsibilities to comply with all applicable laws, including
Sections 13 and 16 of the Securities Exchange Act of 1934.

     This Power of Attorney shall remain in full force and effect until revoked
by the undersigned in a signed writing delivered to the foregoing attorney-in-
fact.

     IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this 3rd day of November, 2022.

/s/ Janice McCourt
Name: Janice McCourt