1. Department of Spine Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, P. R. China
2. Department of Materials Science and State Key Laboratory of Molecular Engineering of Polymers, Academy for Engineering and Technology, Fudan University, Shanghai 200433, P. R. China
3. Department of Neurosurgery, Xinhua Hospital School of Medicine, Shanghai Jiaotong University, Shanghai 200092, P. R. China
4. Research Center for Translational Medicine, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen 361003, P. R. China
5. Department of Rehabilitation, Zhongshan Hospital, Fudan University, Shanghai 200032, P. R. China