Bridging areas of injury in the spinal cord.

There is a devastating loss of function when substantial numbers of axons are interrupted by injury to the spinal cord. This loss may be eventually reversed by providing bridging prostheses that will enable axons to regrow across the injury site and enter the spinal cord beyond. This review addresses the bridging strategies that are being developed in a number of spinal cord lesion models: complete and partial transection and cavities arising from contusion. Bridges containing peripheral nerve, Schwann cells, olfactory ensheathing glia, fetal tissue, stem cells/neuronal precursor cells, and macrophages are being evaluated as is the administration of neurotrophic factors, administered by infusion or secreted by genetically engineered cells. Biomaterials may be an important factor in developing successful strategies. Due to the complexity of the sequelae following spinal cord injury, no one strategy will be effective. The compelling question today is: What combinations of the strategies discussed, or new ones, along with an initial neuroprotective treatment, will substantially improve outcome after spinal cord injury?