1. From the Vascular Biology Program (C.K.T., B.M., A.R., A.M., K.G., A.L.B., D.E.I.) and Departments of Pathology (D.E.I.), Surgery (C.K.T., B.M., A.M., K.G., D.E.I.), and Medicine (B.M.), Harvard Medical School and Children’s Hospital, Boston; and Wyss Institute for Biologically Inspired Engineering and Harvard School of Engineering and Applied Sciences (D.E.I.), Cambridge, Mass.