[1] Peking Univ, Sch & Hosp Stomatol, Ctr Craniofacial Stem Cell Res & Regenerat, Dept Orthodont, Beijing 100081, Peoples R China
[2] Tsinghua Univ, Sch Mat Sci & Engn, Beijing 100084, Peoples R China
[3] Chinese Acad Sci, Inst Chem, Beijing Natl Lab Mol Sci, State Key Lab Polymer Phys & Chem, Beijing 100190, Peoples R China
[4] Univ Chinese Acad Sci, Beijing 100049, Peoples R China
[5] Harvard Med Sch, Brigham & Womens Hosp, Dept Med, Div Engn Med, Cambridge, MA 02139 USA