miR-19b-3p regulates autophagy of BMSCs in hypoxia through PTEN/Akt/mTOR pathway to promote fracture healing
摘要
Bone marrow mesenchymal stem cells (BMSCs) play a significant role in bone defect repair. Currently, the limited survival and function of transplanted BMSCs pose major obstacles to tissue repair mediated by these cells. Therefore, the exploration of BMSCs transplantation activity has become an urgent clinical problem. In this experiment, we constructed lentiviral vectors with overexpression and silencing of miR-19b-3p and utilized a rat fracture model. The effects of BMSCs proliferation were examined using CCK-8, the Annexin V-FITC apoptosis kit and TUNEL assay, the effects of BMSCs osteogenic differentiation were detected using ALP and Alizarin red staining. Furthermore, Western blotting and qRT-PCR were employed to examine the expression of key proteins in the PTEN/Akt/mTOR signaling pathway and autophagy-related proteins. Moreover, the impact of miR-19b-3p on bone microstructure was assessed using Micro CT, HE, Safranin O/Fast Green, as well as Masson staining, and Immunohistochemistry analysis examined PTEN, p62 and Runx2 expression levels on fracture site. By constructing lentiviral vectors with overexpression and silencing of miR-19b-3p, we found that silencing miR-19b-3p significantly promoted the proliferation as well as the osteogenic differentiation of BMSCs under hypoxia. Western blotting and qRT-PCR results showed that silencing miR-19b-3p significantly increased PTEN, LC3, and Beclin1 expression while decreasing p-Akt, p-mTOR, and p62 expression. Furthermore, by constructing the fracture rats and administering hypoxia-treated BMSCs transfected with miR-19b-3p via tail vein injection, we found that silencing miR-19b-3p obviously increased the formation of trabecular and promoted the healing of the fractures. Immunohistochemistry analysis showed that silencing miR-19b-3p upregulated PTEN and Runx2 expression levels and suppressed p62 expression with statistical significance. In summary, these findings suggest that miR-19b-3p may regulate BMSCs’ autophagy and osteogenic differentiation under hypoxia via the PTEN/Akt/mTOR signaling pathway, thereby promoting fracture healing and providing a potential target for the treatment of fractures.