1. Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
2. Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
3. Department of Orthopaedic and Traumatology, The University of Hong Kong, 21 Sassoon Road, Pokfulam, Hong Kong, China