GDNF基因体内转染对大鼠脊髓损伤后轴突再生的影响

目的：研究脂质体介导的胶质细胞源性神经营养因子（GDNF）基因在大 鼠损伤脊髓内的表达，观察外源性GDNF对损伤脊髓轴突再生的作用。方法：利用Nystrom法制备大鼠胸髓压迫损伤模型。以直接注射法将脂质体DC－Chol和重组质粒pEGFP－GDNF cDNA混合后注入大鼠损伤脊髓。采用RT－PCR技术和荧光显微镜检测GDNF基因转染后的体内表达，并通过辣根过氧化酶（HRP）顺行追踪技术和神经微丝（NF）、胶质原纤维酸性蛋白（GFAP）免疫组化活性的变化来评价GDNF基因转染对轴突再生的影响。结果：经脂质体DC－Chol介导GDNF基因可有效地转染脊髓组织 中并得到表达。GDNF转基因4周后可明显增加NF阳性轴突数目，促进皮质脊髓束再生并通过损伤区。结论：外源性GDNF在损伤区局部高表达具有神经损伤保护作用，提示阳离子脂质体介导GDNF体内转基因治疗创伤性脊髓损伤的方法是可行的。

Effect of GDNF gene transfer in vivo on axon regeneration after spinal cord injury in rats

Objective: To examine the expression of glial cell line derived neurotrophic factor (GDNF) in injured spinal cord and to observe effect of exogenous GDNF on the regeneration of injured axons. Methods: The model of compressive spinal cord injury (SCI) was established in rats by the method of Nystrm. The recombinant plasmid pEGFP GDNF and DC Chol liposome complexes were injected into injured spinal cord. RT PCR and fluorescence observation confirmed the presence of GDNF cDNA expression 1 week after injection. Using HRP anterograde tracing and immunohistochemical staining of GFAP and NF, the effect of GDNF gene transfer in vivo on axon regeneration in the injured spinal cord was observed. Results: The spinal cord was infected by injection of the DC Chol mediated GDNF cDNA transfer and expressed the GDNF. GDNF gene transfer obviously increased the number of NF positive axons and promoted regeneration of corticospinal tract in injured region. Conclusion: In vivo transfer of GDNF cDNA can, to some extent, protect the injured axons through increasing local expression of exogenous GDNF. Liposome mediated delivery of GDNF cDNA may be a practical gene transfer method for treating traumatic SCI.