LONG-SEGMENT NERVE ALLOGRAFT REGENERATION IN THE SHEEP MODEL - EXPERIMENTAL-STUDY AND REVIEW OF THE LITERATURE

Experimental work in the Held of nerve allotransplantation has dealt w ith the feasibility of nerve allografts reconstructing nerve gaps. In the majority of studies, the nerve gap studied has been short, and som e degree of regeneration has been achieved, even in the untreated allo graft. To better approximate clinical nerve-allograft reconstruction, a series of long-segment (8-cm) nerve allografts were performed in the ovine model. Twenty outbred ewes were randomized into two experimenta l groups with four experimental conditions. Animals received nerve all ografts treated under one of the following conditions: fresh nerve aut ograft, fresh nerve allograft, cold-preserved nerve autograft, or cold -preserved nerve allograft. The nerve grafts were examined and compare d at 6 and 10 months, using histological, morphometric, and electrophy siologic analyses. The results of the study demonstrated that, while e xcellent regeneration occurred across the nerve autograft, the long ne rve allograft could not support axonal elongation. Similarly, cold ner ve preservation did not enhance regeneration. The sheep animal model a llows for investigation of the Long nerve gap and may be beneficial in a better correlation of experimental nerve transplantation with clini cal conditions.