1 The Biotherapy Center, the Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
2 Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, Guangdong, China.
3 Department of Oral and Maxillofacial Surgery & Pharmacology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States.