Bone Morphogenetic Protein 7 Gene-infected Bone Mesenchymal Stem Cells To Repair Neurons After Spinal Cord Injury In Rats

Object:Asthere is no effective treatment for spinal cord injury.This project aims toinduce the differentiation of bone marrow mesenchymal stem cells into neurons by transfection with lentiviral-loaded BMP-7 expression vector,and transplant the BMSCs transfected with lentiviral-loaded BMP-7 expression vector to treat spinal cord injury in rats.Thisstudy can explore the effect of spinal cord injury on neuron repair in rats,and provide new targets and strategies for promoting spinal cord function repair.Methods:The BMSCs of rats were cultured in vitro and randomly divided into normal control group(conventional culture),LV-GFP group(transfected with LV-GFP),and LV-BMP7-GFP group(transfected with LV-BMP7-GFP).Cell morphology was observed with an inverted microscope,cell differentiation ability was measured by adipogenic induction and osteogenic differentiation,cell survival rate was detected by MTT method,the expression of neuron markers NF-200 and SYN 1 was detected by immunocytochemical experiments,and the mRNA expression of NF-200,SYN 1 was detected by qRT-PCR.Allen's percussion device was used to create rat spinal cord injury models,which were randomlydivided into sham operation group(conventional feeding),model group(injection of saline into the spinal arachnoid cavity),BDNF group(injection of BDNF into the spinal arachnoid cavity),BMSCs group(injection of BMSCs into spinal arachnoid cavity),LV-BMP7-BMSCs group(injection of LV-BMP7-BMSCs into spinal arachnoid cavity).After6 h,1 d,3 d,7 d,14 d,21 d,and 28 d of treatment,the hindlimb function of the rats was evaluated by BBB scores,and the expressions of NF-200 and GFAP were detected by histochemical immunochemical experiments,qRT-PCR,and Western Blot.Results:1.After lentivirus transfection,the survival rates of bone marrow mesenchymal stem cells in LV-GFP group and LV-BMP7-GFP group were not significantly different from that before transfection(P>0.05);Three days after infection,the MOI=10 groups had the highest average fluorescence intensity(P<0.05).2.The results of cell immunohistochemistry showed that the expressions of NF-200 and SYN1 in the normal control group and LV-GFP group were negative;the expressions of NF-200 and SYN 1 in the LV-BMP7-GFP group were positive,and the cell bodies and axons were stained bright brownish yellow.3.The qRT-PCR results showed that the relative expression levels of NF-200 and SYN1 mRNA genes in LV-BMP7-GFP group were higher than those in normal control group andLV-GFP group(P<0.05).4.At 14 d after spinal cord injury treatment,the BBB scores of rats in the BDNF group and LV-BMP7-BMSCs group were higher than those of the model group and BMSCs group(P<0.05);after 21 d and 28 d of treatment,the BBB score of rats in the LV-BMP7-BMSCs group was higher than those of model group,BDNF group and BMSCs group(P<0.05).5.Compared with the sham operation group,the expression levels of NF-200 in the spinal cord tissue of rats in the BDNF group,BMSCs group and LV-BMP7-BMSCs group were increased(P<0.05);the expression levels of NF-200 in BDNF group and LV-BMP7-BMSCs group were higher than those in model group and BMSCs group(P<0.05).6.Compared with the sham operation group,the expression levels of GFAP in the other groups after spinal cord injury were increased(P<0.05);there was no significant difference in the expression levels of GFAP between the model group,BDNF group,BMSCs group,and LV-BMP7-BMSCs group(P>0.05).Conclusion:1.BMSCs transfected with lentiviral BMP-7 gene was similar to that of neuron-like cells,and neuron markers were positively expressed.It proved that BMSCs transfected with lentiviral BMP-7 genecan promote BMSCs to differentiate into neurons.2.Transplantation of BMSCs transfected with lentiviral BMP-7 gene to treat spinal cord injury can promote spinal cord injury neuron repairand restore neural function.Provide theoretical basis for clinical treatment of spinal cord injury.