Exhibit 24

				POWER OF ATTORNEY

         Know all by these presents, that the undersigned hereby constitutes and
appoints each of Adam M. Veness, Esq., John D. Quisel, J.D., Ph.D. and Kevin
F. McLaughlin, signing singly, as the undersigned's true and lawful
attorney-in-fact to:

         (1)      execute for and on behalf of the undersigned, in the
                  undersigned's capacity as an officer and/or director of
                  Acceleron Pharma Inc. (the "Company"), Forms 3, 4 and 5 in
                  accordance with Section 16(a) of the Securities Exchange Act
                  of 1934, as amended (the "Act"), and the rules thereunder;

         (2)      do and perform any and all acts for and on behalf of the
                  undersigned which may be necessary or desirable to complete
                  and execute any such Form 3, 4 or 5 and timely file such form
                  with the United States Securities and Exchange Commission and
                  any stock exchange or similar authority; and

         (3)      take any other action of any type whatsoever in connection
                  with the foregoing which, in the opinion of such
                  attorney-in-fact, may be of benefit to, in the best interest
                  of, or legally required by, the undersigned, it being
                  understood that the documents executed by such
                  attorney-in-fact on behalf of the undersigned pursuant to this
                  Power of Attorney shall be in such form and shall contain such
                  terms and conditions as such attorney-in-fact may approve in
                  such attorney-in-fact's discretion.

         The undersigned hereby grants to each 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 if personally present, with full power of substitution or revocation,
hereby ratifying and confirming all the acts such attorney-in-fact 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 each of the
foregoing attorneys-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 Section 16 of the Act.

         This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to each
of the foregoing attorneys-in-fact.

	IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of December 9, 2019.


                   By:  /s/ Jay T. Backstrom, M.D.
                        ------------------------------------------------------

           Print Name:  Jay T. Backstrom, M.D.
                        ------------------------------------------------------