Experimental repair of spinal cord lesions by grafting from CNS to PNS

Based on the previous work of other researchers, we first removed 1 cm of the spinal cord of rats and grafted the gap with peripheral nerve. We obtained progression of regenerating axons inside the grafts, but regrowing axons halted at the distal cord level. We then tried directly to connect the cephalad stump of the cord with the sciatic nerve, several surgical models of which have been previously studied. The latest model uses a homologous sciatic nerve of an inbred Wistar rat, to bridge the gap between the lateral bundle of the cord, proximal to the origin of the sciatic roots, and the sciatic trunk distal to the fusion of its roots. Good reinnervation of the sciatic nerve and distal muscles was found. It was demonstrated by: a) the remyelination of regenerated nerve fibers, not only in the grafts but also in the sciatic nerve; b) re-innervation of motor endplates; and c) clinical and electromyographic muscle responses. Central nervous system (CNS) neurons are able to regenerate not only their axons through the CNS but also into peripheral nerves. The capacity of CNS neurons to neurotize peripheral nerves reaching terminal organs, is a basic finding. Many questions arise from the study, including: Can these results be extrapolated to humans? What would be the function of these regenerated fibers that might lack some of the control mechanisms peculiar to peripheral nerves?