1. a Department of Biomaterials, Field of Tissue Engineering, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawara-cho Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
2. b Hokkaido Industrial Research Institute, Nishi-11, Kita-19, Kita-ku, Sapporo, 060-0819, Japan
3. c Department of Biomaterials, Field of Tissue Engineering, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawara-cho Shogoin, Sakyo-ku, Kyoto 606-8507, Japan; Email: yasuhiko@frontier.kyoto-u.ac.jp