1. Department of Neurosurgery, Houston Methodist Hospital, Houston, Texas, USA.
2. Kentucky Spinal Cord Injury Research Center, Louisville, Kentucky, USA.
3. Christopher & Dana Reeve Foundation, Short Hills, New Jersey, USA.
4. Division of Neurosurgery, Walter Reed National Military Medical Center, Bethesda, Maryland, USA.
5. Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, USA.
6. The Miami Project to Cure Paralysis, University of Miami, Miami, Florida, USA.
7. Division of Neurosurgery and Spine Program, Department of Surgery, University of Toronto, Toronto, Canada.