Regenerative sprouting of retinal ganglion cells of adult hamsters induced by the epineurium of a peripheral nerve.

Although it is known that transplantation of a peripheral nerve (PN) to the damaged central nervous system (CNS) promotes axonal regeneration, the interactions of cellular components of the PN with CNS neurons are still not well defined. Schwann cells in the PN are thought to be the major element involved in supporting CNS regeneration, but very little information exists with regard to whether other PN components also play an active role. Using our previously established model of transplanting a PN segment into the vitreous to stimulate regenerative sprouting of retinal ganglion cells (RGCs), we found that the epineurium isolated from a PN which had been pre-injured by transection was able to induce RGC sprouting when implanted intravitreally. Since the epineurium is composed mainly of connective tissue components and is devoid of Schwann cells, our results suggest that other cellular elements of the PN besides Schwann cells may have the potential to support CNS regeneration.