1. Department of Plastic and Reconstructive Surgery, Institute of Medicine, University of Tsukuba, Tsukuba 305-8575, Ibaraki, Japan
2. Department of Plastic and Reconstructive Surgery, Mito Saiseikai General Hospital, Mito 311-4145, Ibaraki, Japan
3. Laboratory of Regenerative Medicine and Stem Cell Biology, University of Tsukuba, Tsukuba 305-8575, Ibaraki, Japan