CAMBRIDGE, Mass.--(BUSINESS WIRE)--June 21, 2006--Acceleron Pharma, Inc., a biopharmaceutical company involved in the development of regenerative therapeutics , announced that it has initiated a Phase 1 clinical trial of ACE-011, a novel treatment for bone loss disease, particularly osteoporosis. ACE-011 is the first regenerative therapeutic to enter human clinical trials from Acceleron's scientific platform that utilizes the body's own naturally-occurring growth factors.