Spinal cord repair: strategies to promote axon regeneration.

Neurons in the central nervous system have a remarkable capacity to regenerate their transected axons when provided with an appropriate growth environment. Advances in our understanding of axon regeneration have allowed the development of different experimental strategies to stimulate axon regeneration in animal models of spinal cord injury. Growth inhibitory proteins block axon regeneration in the CNS, and many of these proteins have been identified. Various methods that are now used to stimulate regeneration in the injured spinal cord are directed at overcoming the growth inhibitory environment of the CNS. Three general approaches tested in vivo stimulate regeneration in the spinal cord. First, antibodies that bind inhibitory proteins in myelin allow axon regeneration in the CNS. Second, methods that modulate neuronal intracellular signaling allow axons to grow directly on the inhibitory substrate of the CNS. Third, transplantation of cells to the lesioned spinal cord promotes repair. In this paper we review current advances in each of these research domains.