1. Departments of Neurosurgery and Orthopaedic Surgery Perelman School of Medicine, University of Pennsylvania Philadelphia Pennsylvania USA
2. Translational Musculoskeletal Research Center Corporal Michael J. Crescenz VA Medical Center Philadelphia Pennsylvania USA
3. Leni and Peter W. May Department of Orthopaedics Icahn School of Medicine at Mount Sinai New York New York USA
4. Orthopedic Soft Tissue Research Program Hospital for Special Surgery New York New York USA
5. Department of Cell and Development Biology Weill Cornell Medicine, Graduate School of Medical Sciences New York New York USA