1. Department of Orthopaedic and NeuromusculoskeletalSurgery, Faculty of Medical and Pharmaceutical Sciences Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan.
2. Department of Cellular Differentiation, Institute for Frontier Medical Sciences Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.