Monkey Recovery from Spinal Cord Hemisection: Nerve Repair Strategies for Rhesus Macaques.

OBJECTIVE: The repair of spinal cord injury (SCI) using peripheral nerve grafts (PNG) and acidic fibroblast growth factor (aFGF) has demonstrated promising results in rats and a few human patients, but not in non-human primates. Our study verified the effective use of PNG and aFGF for repairing incomplete SCI in non-human primates (rhesus macaques).

METHODS: Six adult non-human primates (rhesus macaques) received spinal cord hemisection at T-8 level and were grouped into the repair and the control groups (n=3 in each). Animals of the repair group underwent nerve repair with autologous PNG plus aFGF immediately after the lesioning. The control group received exactly the same operation for lesioning but no treatment. Post-operative behavioral evaluations, electrophysiological tests (including motor and somatosensory evoked potentials), and magnetic resonance imaging (MRI) were also conducted and compared between the two groups, as well as histological examination of the spinal cord cephalic to, at, and caudal to the lesion site after sacrifice.

RESULTS: Animals of the repair group had better motor function in the lower limbs at every observed time point, and demonstrated more improvement by electrophysiological exams than the control group. The repair group had smaller areas of myelomalacia on magnetic resonance images around the lesion than those of the control, suggesting diminished inflammatory responses with the repair strategy.

CONCLUSION: PNG plus aFGF for SCI in non-human primates yielded improvements in clinical behavior, electrophysiology, and MRI evaluations. The study suggested that the repairing strategy was feasible and effective for non-human primate SCI. Further investigations are warranted to corroborate its effectiveness for clinical application.