1. Department of Regenerative Medicine, Division of Radiation Medical Science, Research Institute for Radiation Biology and Medicine, Hiroshima University , 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551 , Japan
2. Division of Regeneration and Medicine, Hiroshima University Hospital , Hiroshima , Japan
3. Department of Dermatology, Graduate School of Biomedical and Health Sciences, Hiroshima University , Hiroshima , Japan