1. Department of Materials Engineering, School of Engineering; The University of Tokyo; Hongo Bunkyo-ku, Tokyo 113-8656 Japan
2. Division of Science for Joint Reconstruction, School of Medicine; The University of Tokyo; Hongo Bunkyo-ku, Tokyo 113-8656 Japan
3. Research Department; KYOCERA Medical Corporation; Miyahara Yodogawa-ku, Osaka 532-0003 Japan
4. National Cerebral and Cardiovascular Center Research Institute; Fujishiro-dai Suita, Osaka 565-8565 Japan