1. From the Russell H. Morgan Department of Radiology and Radiological Science (D.L.K., M.T., W.D.G., T.I., D.K., P.W., W.P.S., H.H.C., D.F., I.I., M.S., B.M.W.T., R.L.W., J.W.M.B.) and Institute for Cell Engineering (D.K., P.W., J.W.M.B.), Johns Hopkins University School of Medicine, Baltimore, Md; Osiris Therapeutics, Inc, Baltimore, Md (R.G.Y., M.M., M.F.P.); and School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pa (R.C.B.).