The Effect And Mechanism Of MiR-21 In Myofibroblast Differentiation Of Rat Bone Mesenchymal Stromal Cells

Studies have shown that radiation-induced fibroatrophic process plays an important role in the osteoradionecrosis of the jaws. mi R-21 may be involved in the RIF and is considered as an important mediator in it. Objective: The aim of this study was to investigate the influence of TGF-β1 on the gene of mi R-21 of rat bone mesenchymal stromal cells. And to investigate the role of mi R-21 in the jaw of fibrosis in vitro.Methods: 1. Whole bone marrow adherence on plastic was used to isolation and culture rat bone mesenchymal stromal cells. When passage 3, the cells were treated with TGF-β1 for different periods of time and concentration. The target gene expression of mi R-21 was detected by real-time PCR; 2. Over-expression of mi R-21 by mi R-21 mimics and down-regulation of mi R-21 by mi R-21 inhibitor, the expression levels of mi R-21 after transfection were confirmed by real time RT-PCR. To study whether up-regulated mi R-21 or down-regulation of mi R-21 affect myofibroblast differentiation of rat bone mesenchymal stromal cells by RT-PCR and western blot; 3. Over-expression of mi R-21 by mi R-21 mimics, the expression levels of mi R-21 after transfection were confirmed by real time RT-PCR. After one day of transfection, rat BMSCs were treated with 5ng/ml TGF-β1. To study whether the mi R-21 effect of myofibroblast differentiation of rat mesenchymal stromal cells is related with TGF-β1 by western blot and immunohistochemistry.Results: Real-time PCR demonstrated that TGF-β1 induced mi R-21 expression in a time-dependent and dosage-dependent manner, peaking at 48 h with an optimal dose at 5ng/ml. The expression of myofibroblast related protein and gene α-SMA was up-regulated. The rat bone mesenchymal stromal cells transfected with mi R-21 mimics could increase the expression of α-SMA, while inhibiting mi R-21 leaded to decreasing of the expression of α-SMA. In addition, up-regulation of mi R-21 could increase the effect of TGF-β1 on myofibroblast differentiation of rat bone mesenchymal stromal cells.Conclusion: TGF-β1 signaling pathway played a vary important role in mi R-21 expression. mi R-21 could promote myofibroblast differentiation of BMSCs in vitro. Inhibition of mi R-21 may be a therapeutic approach to suppress fibrosis of jaws.