坐骨神经瓦勒变性大鼠许旺细胞生物学特性及分泌功能变化

Effects of Wallerian degeneration on biological characteristics and secretory function of Schwann cells in rats with sciatic nerve injury

背景:研究表明外周神经损伤后,许旺细胞在基底膜管内形成Bunger带,引导再生轴突延伸,但具体作用机制目前尚不清楚。目的:观察大鼠坐骨神经损伤后瓦勒变性对许旺细胞生物学特性及分泌功能的影响。方法:建立大鼠坐骨神经横切模型,分为坐骨神经瓦勒变性组(坐骨神经横断组)和手术对照组。采用神经段单酶消化法分离培养许旺细胞,光镜下观察细胞形态变化,S-100免疫荧光鉴定。取第1代许旺细胞,利用计数法绘制14 d内许旺细胞的生长曲线,MTT法检测14 d内许旺细胞增殖活性,酸性磷酸酶法检测许旺细胞黏附能力,ELISA法检测神经生长因子浓度。结果与结论:坐骨神经段培养第14天,坐骨神经横断组神经段边缘可见大量许旺细胞,呈线形排列;手术对照组许旺细胞数量少,呈散在分布,两组许旺细胞S-100均呈阳性表达。许旺细胞传代培养第3天,两组许旺细胞均进入对数增长期,随时间延长,细胞数及细胞增殖吸光度值均呈上升趋势,坐骨神经横断组细胞数及增殖吸光度值明显高于手术对照组(P<0.05);坐骨神经横断组许旺细胞黏附能力明显高于手术对照组(P<0.05);ELISA法检测示,坐骨神经横断组神经生长因子浓度在培养第4,6,8,10,12,14天时均高于手术对照组(P<0.05)。结果表明大鼠坐骨神经损伤后两三周,瓦勒变性对许旺细胞生物学功能具有显著影响,可诱导许旺细胞幼稚化,促使许旺细胞在短期内迅速分裂增殖,并分泌大量神经营养因子及细胞外黏附成分,为再生轴突的延伸提供适宜的神经微环境;并增加细胞黏附能力,为外周神经损伤修复提供适宜的神经微环境。

BACKGROUND：Studies have shown that Schwann cells form a Bunger band in the basement tube and guide the extension of regenerating axons after peripheral nerve injury, but the exact mechanism remains to be explored. OBJECTIVE：To explore the effect of Wal erian degeneration on biological characteristics and secretory function of Schwann cells in rats with sciatic nerve injury. METHODS：A rat model of sciatic nerve injury was established and divided into two groups：sciatic nerve transection group and surgical control group. Schwann cells were isolated and cultured from sciatic nerve segments by one enzyme digestion. The cellmorphology was observed under light microscope and S-100 protein expression was determined by immunofluorescence staining. After subculture, the first generation of Schwann cells were chosen to draw the growth curve by the counting method within 14 days. The cellactivity was detected by MTT assay. The adhesion of Schwann cells was examined by acid phosphatase analysis and the concentration of nerve growth factor was detected by ELISA method. RESULTS AND CONCLUSION：At 14 days after primary culture, a great number of Schwann cells were observed near the edges of nerve segments in the sciatic nerve transection group, but only smal number of Schwann cells scattered around nerve segments in the control group. Schwann cells in both groups showed S-100 positive expression. At 3 days after subculture, Schwann cells reached the logarithm proliferative phase, the cellnumber and proliferation absorbance values in both groups were increased along with time extension. Furthermore, the number of Schwann cells and absorbance value in the sciatic nerve transection group were significantly higher than those of control group （P〈0.05）. The adhesion ability in the sciatic nerve transection group was also significantly higher than those in the control group （P〈0.05）. ELISA results showed that, the concentrations of nerve growth factor in the sciatic nerve transection group were significantly higher than those in the control group at 4, 6, 8, 10, 12 and 14 days （P〈0.05）. After sciatic nerve injury, Wal erian degeneration can induce Schwann cells dedifferentiate into the precursors, significantly influence the biological function of Schwann cells, promote the proliferation of Schwann cells within the short term, secrete large amounts of neurotrophic factors, enhance celladhesion, and provide a suitable microenvironment for regenerated axons. In addition, it creates the necessary microenvironment for peripheral nerve regeneration.