1. Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
2. Stem Cell Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
3. Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan
4. Center for Regenerative Sports Medicine, Steadman Philippon Research Institute, Vail, Colorado, USA
5. Department of Orthopaedic Surgery, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA