Regenerative medicine may be defined as the process of replacing or "regenerating" human cells, tissues or organs to restore or establish normal function. This field holds the promise of regenerating damaged tissues and organs in the body by replacing damaged tissue or by stimulating the body's own repair mechanisms to heal tissues or organs. Regenerative medicine also may enable scientists to grow tissues and organs in the laboratory and safely implant them when the body is unable to heal itself. Current estimates indicate that approximately one in three Americans could potentially benefit from regenerative medicine. Regenerative Medicine refers to a group of biomedical approaches to clinical therapies that may involve the use of stem cells. Examples include cell therapies (the injection of stem cells or progenitor cells); immunomodulation therapy (regeneration by biologically active molecules administered alone or as secretions by infused cells); and tissue engineering (transplantation of laboratory grown organs and tissues).