Axonal regeneration stimulated by the combination of nerve growth factor and ciliary neurotrophic factor in an end-to-side model

The aim of this study was to investigate the potential for stimulating axon al regeneration in the context of end-to-side coaptation using a combinatio n of nerve growth factor and ciliary neurotrophic factor in the rat sciatic nerve model. Four experimental groups (n = 8) were used: end-to-side coapt ation only, end-to-side coaptation plus growth factor injection, primary re pair, and nontransferred gap control. Twenty weeks after surgery histologic analysis showed that the ratio of axon density was significantly increased for the growth factor injection group. Histologic evidence suggested conta mination from the proximal peroneal stump. Electrical stimulation and muscl e weights showed that the target muscles had been reinnervated in all group s except the nontransferred gap control group. These data support the concl usion that the use of nerve growth factor and ciliary neurotrophic factor i n combination may enhance regeneration in the peripheral nervous system. Th is is consistent with previous reports on the central nervous system and su ggests a potential application in future studies aimed at improving periphe ral nerve regeneration. Another conclusion is that contamination from the p roximal peroneal stump may explain the regeneration observed in the end-to- side model. Further study using retrograde labeling is needed to establish the origin of the regenerating axons. Finally, evidence suggests that regen erating axons can use the epineurium of an intact nerve to bridge a gap in continuity. Copyright (C) 2001 by the American Society for Surgery of the H and.