局部持续分泌神经生长因子促周围神经再生作用的研究

目的探讨以微囊化基因修饰细胞为载体,在局部持续分泌神经生长因子(nerve growth factor,NGF)促周围神经再生的作用。方法NGF基因修饰3T3细胞(3T3-NGF),采用微胶囊制备技术制备微囊化的3T3-NGF细胞;体外培养后分别检测活性和生物活性。选取SD大鼠制备坐骨神经横断损伤模型后,随机分微囊化3T3-NGF细胞移植组(A组)、裸3T3-NGF细胞移植组(B组)、空胶囊移植组(C组)和阴性对照组(D组)。术后不同的时间采用组织形态学检查分别观察各组坐骨神经恢复情况。结果3T3-NGF细胞在微胶囊内保持正常活性和增殖能力,可以持续分泌NGF。移植术后A组的患肢恢复情况好于B,C和D组。移植术后4,8及12周时,各组动物行组织形态学检查,显示A组的损伤远端神经纤维密度、轴突直径和髓鞘厚度等评价神经再生的指标均优于B,C和D组(P<0.05),而B,C和D三组之间差异无显著性(P>0.05)。结论体外培养的3T3-NGF细胞,在微胶囊内可保持正常的增殖能力和生物活性;微囊化3T3-NGF细胞移植到大鼠周围神经损伤的局部,在微胶囊的免疫保护下,可持续分泌NGF,有促进周围神经再生修复的作用。

Effects of Continuous Local Release of Nerve Growth Factor on Peripheral Nerve Regeneration following Nerve Injury

Objective To investigate the effect of locally continuous release of nerve growth factor(NGF) on the sciatic nerve regeneration following injury in rats.Methods Using drop generative technique,microencapsules containing cells modified by NGF gene were prepared.The cell viability and bioactivity were determined.After sciatic nerve was cut and sutured,96 Sprague-Dawely rats were divided into four groups at random,Group A(in vivo implantation of microencapsulated cells modified by NGF gene),Group B(in vivo implantation of microencapsule),Group C(in vivo implantation of cells modified by NGF gene),and Group D(negative group).The number and diameter of regenerating myelinated axons and the thickness of myelinated sheath were detected respectively in the 4thd,the 8th,and the 12th week after implantation.Results The production of NGF in cultural supernatant of microencapsulated cells could be determined after culture,and maintained about 70 days in vitro.The number and diameter of regenerating myelinated axons and the thickness of myelinated sheath were larger in Group A than in any other group(P< 0.05).Conclusion The cells modified by NGF gene in microencapsules retain reliable cell viability and function.After implantation,microencapsuleted cells modified by NGF gene may secrete NGF continuously in vivo,and had significant promoting effect on nerve regeneration following sciatic nerve injury.