沉默微小RNA-378靶向调节骨形态发生蛋白2/母亲DPP同源物4信号通路对大鼠胫骨骨折愈合的影响实验研究OACSTPCD

Objective:To investigate the effect of microRNA-378(miR-378)silencing on tibial fracture healing by targeting bone morphogenetic protein(BMP)2/maternal DPP homolog(Smad)4 signaling pathway in rats.Meth-ods:The tibial fracture model was established in 38 rats,and 18 normal rats were selected as sham operation group.Eight rats in the tibial fracture model were selected as modeling group,and eight rats in the sham operation group were selected as control group.RT-qPCR was used to detect the expression of miR-378,BMP2 and Smad4 mRNA in bone tissue of tibial fracture site in the modeling group and normal bone tissue of the same site in the control group.Thirty tibial fracture model rats were randomly divided into model group,no-loaded plasmid group and miR-378 si-lencing group,with 10 rats in each group.The no-loaded plasmid group and the miR-378 silencing group were injec-ted with 1 μg no-loaded plasmid or miR-378 small interfering RNA(siRNA)plasmid through the tail vein,respec-tively;the model group and the remaining 10 rats in the sham operation group were injected with 1 μg 0.9％sodium chloride solution through the tail vein;the rats were injected once every 2 days for 30 consecutive days.The tibial fracture healing of each group was observed by X-ray and the fracture healing score(Lane-Sandhu score)was per-formed;serum levels of inflammatory factors,osteocalcin(OC)and alkaline phosphatase(ALP)were detected by enzyme linked immunosorbent assay;the changes of bone morphology were observed by HE staining;the miR-378,BMP2 and Smad4 mRNA expression in bone tissues were detected by RT-qPCR;the protein expressions of BMP2 and Smad4 in bone tissues were detected by Western blot.Results:The expression level of miR-378 in bone tissue of modeling group was significantly higher than that of control group,and the mRNA expression levels of BMP2 and Smad4 were significantly lower than those of control group(all P＜0.05).The bone structure of rats in sham opera-tion group was clear;in the model group and the no-loaded plasmid group,the fracture line was clear,no callus ap-peared,bone structure was seriously damaged,and only a few osteoblasts were generated;in miR-378 silencing group,the fracture line was blurred,callus appeared,the degree of bone tissue destruction was relieved,and a large number of osteoblasts were generated.Compared with sham operation group,the levels of serum TNF-α,IL-1β,OC,ALP and the level of miR-378 in bone tissue in model group were significantly increased,while the mRNA and pro-tein levels of BMP2 and Smad4 were significantly decreased(all P＜0.05).Compared with model group and no-load-ed plasmid group,the Lane-Sandhu score,OC,ALP,BMP2,Smad4 mRNA and protein expression levels in miR-378 silencing group were significantly increased,and the levels of serum TNF-α,IL-1β and the level of miR-378 in bone tissue were significantly decreased(all P＜0.05).Conclusion:Silencing miR-378 may reduce inflammatory response and promote osteoblast generation in tibial fracture rats by targeting activation of BMP2/Smad4 signaling pathway,thus accelerating healing of fracture sites in rats.