Puerarin improves graft bone defect through microRNA-155-3p-mediated p53/TNF-α/STAT1 signaling pathway

Bone graft defects may lead to dysfunction of bone regeneration and metabolic disorders of bone mesenchymal stem cells (BMSCs). Puerarin has demonstrated pharmacological activities in the treatment of human metabolic diseases. The purpose of the present study was to investigate the role of puerarin and to explore its possible protective mechanism of action in rats with bone grafts. A bone graft rat model was established using bone grafting surgery and the rats received puerarin or PBS. Reverse transcription-quantitative PCR, western blot, TUNEL, immunofluorescence and immunohistochemistry assays were used to analyze the beneficial effects of puerarin on bone repair. The results demonstrated that puer-arin effectively ameliorated pathological graft bone defects, decreased bone loss and apoptosis of BMSCs, promoted BMSC proliferation and differentiation, and increased bone mass and the parameters of bone formation in rats with bone grafts. Puerarin decreased the levels of pro-inflammatory cytokines [tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-17A, IL-6 and transforming growth factor (TGF)-β1] and increased the levels of anti-inflammatory cytokines (IL-2 and IL-10) in the serum compared with the PBS group. Puerarin treatment was associated with lower serum alanine transaminase, glutamic oxaloacetic transaminase, γ-glutamyl transferase, alkaline phosphatase, direct bilirubin and total bilirubin levels compared with those in the PBS group in experimental rats. The expression of microRNA-155-3p (miR-155-3p) was upregulated, whereas that of p53, TNF-α and signal transducer and activator of transcription (STAT)1 was downregulated in BMSC cultures of puerarin-treated rats. In vitro assay demonstrated that knockdown of miR-155-3p increased p53, TNF-α and STAT1 expression in BMSCs, and blocked puerarin-regulated p53/TNF-α/STAT1 signaling. Most importantly, miR-155-3p knockdown inhibited puer-arin-regulated apoptosis, proliferation and differentiation of BMSCs. Moreover, the results demonstrated that puerarin regulated vascular endothelial growth factor expression via the miR-155-3p signaling pathway. In conclusion, the results of the present study demonstrated that the upregulation of miR-155-3p induced by puerarin promoted BMSC differentiation and bone formation and increased bone mass in rats with bone grafts, thereby supporting the potential application of puerarin in the prevention of bone graft defects.