1. Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115, USA;
2. CFD Research Corporation, Huntsville, Alabama 35806, USA
3. Vascular Biology Program and Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
4. Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, Massachusetts 02139, USA