1. a Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, School of Medicine Zhejiang University, Hangzhou, People's Republic of China
2. b Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine Zhejiang University, Hangzhou, People's Republic of China
3. c China Orthopaedic Regenerative Medicine (CORMed), Hangzhou, People's Republic of China
4. d Faculty of Medicine, Department of Orthopaedics & Traumatology The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, People's Republic of China
5. e Stem Cells and Regenerative Medicine Laboratory Lui Che Woo Institute of Innovative Medicine, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, People's Republic of China
6. f Faculty of Dentistry, Department of Endodontology The University of Hong Kong, Hong Kong, People's Republic of China