1. Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
2. Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA.
3. David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
4. Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA.
5. Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.