1. Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
2. Graduate School of Science and Technology, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
3. Department of Translational Research & Cellular Therapeutics, Arthur Riggs Diabetes & Metabolism Research Institute of City of Hope, 1500 E. Duarte Rd., Duarte, CA 91010, USA
4. Graduate School of Life and Environmental Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan