1. Department of Experimental Surgery, Surgical Clinic, Charité Campus Virchow, University Medicine, Berlin, Germany.
2. Department of Anatomy and Electron Microscopy, Charité Campus Mitte, University Medicine, Berlin, Germany.
3. Department of Experimental Surgery, Surgical Clinic, Charit. Campus Virchow, University Medicine, Berlin, Germany.
4. McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.