DEVELOPING TRANSPLANTATIONS RELEVANT TO HUMAN INJURY
Mary B. Bunge, Ph.D. • Patrick M. Wood, Ph.D.
Martin Oudega, Ph.D. • Naomi Kleitman, Ph.D.

Previous studies at the Miami Project have established the effectiveness of Schwann cell bridges to promote regeneration of nerve fibers across a transected spinal cord. While many scientists have used transected SCI models to test regeneration approaches, human SCI typically results in a contusion or crushing of the spinal cord rather than a transection. To our knowledge, Drs. Bunge, Wood and Oudega are the first to evaluate the capacity of transplanted Schwann cells (SC) and/or olfactory ensheathing glia (OEG) to spare nerve fibers and promote regeneration in contusive SCI. The cells were injected into the injury site one week after the contusion. Their results showed axons growing in all grafts. Myelination of these fibers was greatest in the animals that received SC alone. Significant sparing of nerves originating in the brain was seen in the group that received SC alone or combined with OEG. They also found that animals that had received the injection of SC alone exhibited better recovery of hindlimb function.

Besides enhancing sprouting and regeneration, researchers feel that myelination of regenerating nerve fibers will be important in restoring function. In this second study, Dr. Wood and colleagues report that while OEGs may be useful to promote regeneration, they do not form myelin. SCs do form myelin and may be an important component of a graft to myelinate regenerating axons. The results of these and previous studies suggest that SCs alone injected into the lesion with OEGs injected on either side may be a useful strategy. In experimental injuries similar to those seen in humans, researchers continue to work to determine the best combination of strategies to promote regrowth, remyelination and reconnection of damaged nerve tissue.