Predegenerated peripheral nerve grafts rescue retinal ganglion cells from axotomy-induced death

The inability of axons to grow across damaged central nervous system tissue is a well-known consequence of injury to the brain and spinal cord of adul t mammals. Our previous studies showed that predegenerated peripheral nerve grafts facilitate neurite outgrowth from the injured hippocampus and that this effect was particularly distinct when 7-, 28-, and 35-day-predegenerat ed nerve grafts were used. The purpose of the present study was to use the above method to induce and support the regrowth of injured nerve fibers as well as the survival of retinal ganglion cells (RGCs). Adult Sprague-Dawley rats were assigned to three groups. In the experimental groups transected optic nerve was grafted with peripheral nerve (predegenerated for 7 days (P D) or nonpredegenerated). In the control group, the optic nerve was totally transected. RGCs and growing fibers labeled with fluorescent tracers were examined. They were counted and the results were subjected to statistical a nalysis. Retinal ganglion cells survived in the groups treated with predege nerated as well as nonpredegenerated grafts; however, the number of survivi ng retinal ganglion cells was significantly higher in the first one. In bot h groups the regrowth of the transected optic nerve was observed but the di stance covered by regenerating fibers was longer in the PD group. No fibers inside grafts and no labeled cells in retinas were present in the control animals. On the basis of the obtained results we can state that the predege neration of grafts enhance their neurotrophic influence upon the injured re tinal ganglion cells. (C) 2001 Academic Press.