Abstract:

Objective To investigate the survival，differentiation and gene expression of hBDNF⁃BMSCs in the spinal cord of rats and their repair effects on spinal cord injury（SCI）in rats. Methods The BMSCs of a SD rat were extracted and cultured to construct hBDNF ⁃ BMSCs. Another 96 SD rats were randomly divided into sham operation group，injury control group，empty vector ⁃BMSCs group，hBDNF ⁃BMSCs group. The rat SCI model was established by the modified Allen heavy object method，and hBDNF⁃BMSCs transplantation was performed one week later. BBB score and cortical somatosensory evoked potential（CSEP）were used to evaluate the nerve function of rats before and after treatment. The histomorphological changes of injured spinal cord segments in rats were observed. The expressions of NeuN，GFAP，p⁃NF⁃H and GAP⁃43 were detected by immunohistochemistry. Results The BMSCs was successfully extracted and the hBDNF⁃BMSCs was constructed. The neurological function in the hBDNF BMSCs group was significantly improved as compared with the vector⁃BMSCs group and the injury control group（P < 0.05）. After 6 weeks transplantation，the P1 wave latency of the lower limb CSEP in the hBDNF ⁃ BMSCs group was significantly shortened，and the P1 ⁃N1 amplitude was the largest. The hBDNF expression in the hBDNF ⁃ BMSCs group was at the highest level in the first week，and even visible at 6th week. In the hBDNF⁃BMSCs group and the empty carrier⁃BMSCs group，the spinal cord tissue structure in the injured area was relatively complete. The spinal cord tissue structure in the injured control group was disordered，and the glial scar formation was seen. As compared with the injury control group and the empty vector⁃BMSCs group，the NeuN expression was significantly increased， the GFAP expression was significantly reduced，and the p⁃NF⁃H，GAP⁃43 expressions were significantly increased and arranged regularly in the hBDNF ⁃BMSCs group six weeks after transplantation. Conclusion Locally injectedand transplanted hBDNF BMSCs can continuously and stably secrete hBDNF locally，protect the survival of neurons and promote the transformation of transplanted BMSCs into neuron like cells，thus promoting the repair of injured spinal cord in rats.

Key words:

spinal cord injury, bone marrow mesenchymal stem cells, neurotrophic factor, gene therapy, nerve repair