神经寄养修复周围神经损伤对TWEAK-Fn14信号通路的调控及其疗效研究

Peripheral nerve injuries represent one of the most common causes of sensorimotor deficits and lost productivity in adults. Functional reconstruction of long segmental nerve defects typically require the use of nerve grafts. Nevertheless, irreversible muscle atrophy occurs inevitably because of the prolonged denervation period. Terzis et al introduced the "baby-sitter" procedure for the therapy of facial nerve palsy, which involves an end-to-side coaptation of the ipsilateral facial nerve trunk to the hypoglossal nerve with 40% neurectomy, to salvage the facial musculature from denervation atrophy. The current study was designed to apply the "baby-sitter" procedure to the treatment of peripheral nerve defects. Different percentages of tibial nerve neurectomy and an end-to-side neurorrhaphy were carried out to reinnervate the transectioned fibular nerve. The effect of partial neurectomy to the donor and receptor nerve and muscle, as well as the fiber regeneration of the impaired nerve, were observed. In addition, the expression of neurotrophic factors in spinal cord and TWEAK-Fn14 pathway related factors in muscles were analyzed to explore the molecular mechanism of end-to-side neurorrhaphy. Subsequently, a two-stage procedure was conducted to repair the transfected fibular nerve, with or without a "nerve babysitting" treatment. The nerve regeneration and degree of muscle atrophy were evaluated. The neurotrophic factors and TWEAK-Fn14 pathway related factors were also quantitated to understand the molecular mechanism of the "baby-sitter" procedure. The current study design can provide a therapeutic modality for avoiding atrophy of the denervated muscles in the treatment of large nerve defects.

周围神经损伤是感觉、运动功能缺失，劳动力丧失的常见原因。长节段的神经缺损可以应用神经移植物治疗，但难以避免发生失神经性的肌肉萎缩。Terzis在面神经损伤病人的治疗中，通过40%切断的舌下神经端侧吻合寄养受损的面神经，有效避免了面肌的失神经萎缩。我们设想将神经寄养的方法应用于周围神经损伤后再生的研究，首先将大鼠的胫神经部分切断后与腓神经端侧吻合，了解对供、受体神经肌肉结构和功能的影响，并研究神经修复过程中生长因子如IGF-1、BDNF和肌萎缩TWEAK-Fn14通路因子的表达，探讨其影响神经修复和肌萎缩的机制；进而进行神经寄养修复周围神经损伤的研究，观察不同方式的腓神经寄养至胫神经对肌肉萎缩的保护作用和疗效，进一步研究其影响神经修复和肌萎缩TWEAK-Fn14通路的分子机制，探讨应用神经寄养来防治长节段神经缺损修复中肌肉失神经萎缩的可能性。

周围神经损伤是感觉、运动功能缺失，劳动力丧失的常见原因。既往研究指出，周围神经损伤两个月以后，失去神经营养的肌肉内的运动单元数量下降；失神经支配六个月之后，即使在外观结构上修复了神经，肌肉萎缩和肌力下降也难以恢复。我们将神经寄养的方法应用于周围神经损伤后再生的研究。我们将大鼠腓神经切断后，按照不同显微外科修复方式行神经外膜吻合；以及按不同横切比例的端侧吻合。术后不同时间段观察神经肌肉的恢复情况及探讨相关机制。结果显示部分供体神经切断的端侧吻合可以获得更有效的神经肌肉系统恢复，但术后早期难以避免发生供体系统的损害。对受体神经的修复中，供体神经横切比例与修复效果成正相关，40%供体神经横切和80%供体神经横切的修复效果显著高于20%供体神经横切组和端侧吻合组；TWEAK和Fn-14的表达随着肌肉萎缩程度的减轻而降低，随着时间的推移而减弱；神经寄养通过修复神经，使得TWEAK和Fn-14的表达下降，进而保护肌肉使之萎缩程度减轻。“babysitter”神经寄养法可用于治疗长节段复杂周围神经损伤，早期疗效不及端端吻合，远期可有效恢复神经及其支配肌肉的结构和功能。供体神经寄养较外膜开窗神经寄养对损伤神经的神经纤维再生和肌纤维面积保护更佳，但在肌重维持和肌力恢复方面，两者无明显差异。供体神经寄养法，对脊髓和肌肉中相关生长因子的影响与端端吻合修复相似，可有效促进神经修复和防止肌萎缩；供体神经外膜开窗寄养法，对TWEAK/Fn-14因子的远期影响与供体神经寄养法相似，有一定的肌萎缩保护作用，但脊髓中IGF-1的表达与神经矿置组相当，促进神经修复和轴突再生的效果不及端端吻合和供体神经养法。