Wenguo Cui1, Hélder A Santos2, Boyang Zhang3, Y Shrike Zhang4. 1. Department of Orthopedics, Shanghai Key Laboratory for Prevention and Treatment of Bone and Joint Diseases, Shanghai Institute of Traumatology and Orthopedics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, People's Republic of China. 2. Department of Biomedical Engineering and W. J. Kolff Institute for Biomedical Engineering and Materials Science, University of Groningen/University Medical Center Groningen, 9713 AV Groningen, The Netherlands. 3. Department of Chemical Engineering, McMaster University, Hamilton, Ontario L8S 4L8, Canada. 4. Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, Massachusetts 02139, USA.