1. Department of Spinal Surgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian, P.R. China
2. Center for Brain Injury & Repair, Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
3. Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
4. Center for Neurotrauma, Neurodegeneration & Restoration, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, Pennsylvania, USA