Intravitreal transplantation of a segment of peripheral nerve enhances axonal regeneration of retinal ganglion cells following distal axotomy.

Neurons of the central nervous system are able to regenerate their axons into a peripheral nerve (PN) graft when they are axotomized close to the cell bodies. Very few, if any, damaged axons can regrow into the PN graft when the axonal injury is made distant to the cell bodies. We show here that a segment of viable PN transplanted intravitreally enhances the regenerative response of distally axotomized retinal ganglion cells. We hypothesize that trophic substances released from the intravitreal PN segment may enable retinal ganglion cells to regenerate their damaged axons into the PN graft even after a distal axotomy. This suggests that the regenerative behavior of an axotomized neuron is influenced by both the local environment at the damaged tip of the axon and the local environment surrounding the cell body. This finding provides evidence that the PN grafting technique may be useful for repairing long tract pathways in the central nervous system even when the damage is inflicted far away from the cell bodies.