The Effects Of Both Nerve Growth Factor And Ciliary Neurotrophic Factor In Promoting Muscular Neurotization Of Denervated Vascularized Skeletal Muscle

The autologous skeletal muscle transplantation has been used in clinic trials for a long time. But the mechanism of reinnervation of grafted muscle is still unclear, and the way to improve the reinnervation is also uncertain. Previous studies indicate that the muscle fascia is a barrier for the process of reinnervation. Recent researches show that Nerve Growth Factor (NGF) and Ciliary Neurotrophic Factor (CNTF) play an important role in peripheral nerve regeneration.Objective:This study is to investigate the effects of both exogenous NGF and CNTF in the process of muscular neurotization of denervated vascularized skeletal muscle.Methods:A modified model of autologous skeletal muscle transplantation was established. Rats were divided randomly into four groups: the NGF treatment group, the CNTF treatment group, the combined NGF and CNTF treatment group and the control group. After a part of fibularisnerve was removed, the fibularis longus muscle whose fascia was removed was transplanted into the gastrocnemius muscle, leaving the two muscles in tight contact to each other. From the operation day to the 7th day after operation, daily dose of NGF (0.5 u g/per hind limb), CNTF (0.0511 g/per hind limb), combined NGF (0.025 u g/per hind limb) and CNTF (0.01 u g/per hind limb) and saline were used in the operative site. At various times after operation, we examined the grafted muscle with histological, histochemical, electron microscope and immunohistochemical methods.Results:The results show that NGF, CNTF, combined NGF and CNTF used in the three treatment groups were all effective in promoting muscular neurotization and diminishing denervated muscle atrophy in grafted denervated skeletal muscle in contrast to the control group. At one month after operation, the effects were seen in the sections stained by routine hematoxylin and eosin, acetylcholinesterase, immunohistochemistry, and in the ultrastructure of the graft. At three months, the reinnervation was almost recovered as normal. The combined use of NGF and CNTF in group 3 was more effective in promoting muscular neurotization.Conclusions:1. The model we designed can be used to study muscularneurotization.2. NGF can promote the muscular neurotization and diminish denervated muscle atrophy.3. CNTF can promote the muscular neurotization and diminish denervated muscle atrophy.4. Combination of NGF and CNTF can also promote the muscular neurotization and diminish denervated muscle atrophy.5. Combination of NGF and CNTF is more effective than NGF and CNTF are used separately; and NGF is more effective than CNTF when they are used separately.Our results demonstrate that NGF and CNTF injected into the operative site can promote the reinnervation of denervated muscle and diminish the denervated muscle atrophy; these findings are of great theoretical and clinical values for skeletal muscle transplantation.