Astragaloside IV Improves Tibial Defect in Rats and Promotes Proliferation and Osteogenic Differentiation of hBMSCs through MiR-124-3p.1/STAT3 Axis

Astragaloside IV (AST-IV) facilitates the proliferation and migration of osteoblast-like cells. We sought to explore the effect and potential mechanism of AST-IV on regeneration of tibial defects. To reveal the effect of AST-IV on regeneration of tibial defects in rat, HE staining and microcomputed tomography (μCT) were performed on tibial bone. The binding relationship between miR-124-3p.1 and STAT3 was analyzed by TargetScan V7.2 and a dual-luciferase reporter assay. Human bone marrow mesenchymal stromal/stem cells (hBMSCs) were identified by morphological observation and flow-cytometric analysis. To reveal the effect and mechanism of AST-IV on phenotypes of hBMSCs, hBMSCs were treated with AST-IV, miR-124-3p.1 mimic, and pcDNA-STAT3, and cell viability, cell cycle, ALP activity, and calcium deposition of hBMSCs in vitro were determined by MTT, flow-cytometric analysis, ELISA, and Alizarin red staining, respectively. The expressions of osteoblast marker molecules (RUNX2, OCN, Smad4), miR-124-3p.1, and STAT3 were indicated by RT-qPCR and Western blot. AST-IV decreased miR-124-3p.1 expression, increased STAT3 expression in tibial bone defects, and promoted regeneration of tibial bone defects in a concentration-dependent manner. The hBMSCs appeared spindle-shaped and were positive for CD105, but negative for CD34. MiR-124-3p.1 negatively regulated STAT3 expression in hBMSCs under osteogenic conditions. AST-IV promoted viability, cell cycle, ALP activity, and osteogenic differentiation of hBMSCs along with increased expressions of osteoblast marker molecules, which was partially reversed by miR-124-3p.1 overexpression. However, the effect of miR-124-3p.1 overexpression on hBMSCs was also partially reversed by STAT3 overexpression. AST-IV improves tibial defects in rats and promotes proliferation and osteogenic differentiation of hBMSCs through the miR-124-3p.1/STAT3 axis.