1. Department of Plastic and Reconstructive Surgery, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido 060-8638, Japan
2. Department of Plastic and Reconstructive Surgery, Otaru Kyokai Hospital, Suminoe-1-6-15, Otaru, Hokkaido 047-8510, Japan
3. Department of Biomaterials, Field of Tissue Engineering, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan