Taohong Siwu decoction promotes the process of fracture healing by activating the VEGF-FAK signal pathway and systemically regulating the gut microbiota

Aims: This study aimed to explore the effect of Taohong Siwu Decoction (THSWD) on bone marrow mesenchymal stem cells (BMSCs) at the cellular level and the possible mechanism of systemic regulation of gut microbiota on fracture recovery.

Methods and results: Cell Counting Kit-8 (CCK-8) experiments show that THSWD effectively promotes the proliferation of BMSCs. Transwell and wound healing assays show that THSWD effectively promotes the invasion and migration of BMSCs. Alizarin red staining showed that the THSWD model enhanced the osteogenic differentiation of BMSCs. Moreover, the effect of THSWD on BMSCs is time- and concentration-dependent. RT-qPCR and western blot results showed that THSWD treatment up-regulated the expression of vascular endothelial growth factor (VEGF) and focal adhesion kinase (FAK) at mRNA and protein levels, respectively. Haematoxylin-eosin and crocin O-quick green staining showed that after 14 days of THSWD treatment, the area of callus and cartilage regeneration at the fracture site increased significantly in rats with right femoral shaft fractures. Gut microbiota was changed in fractured rats, such as the abundance of Bacteroidetes and Firmicutes was increased. THSWD showed positive regulation of both to a certain extent.

Conclusion: THSWD up-regulates VEGF and activates the FAK signalling pathway to enhance the development and differentiation of BMSCs, and systematically regulates the gut microbiota to promote fracture healing.

Significance and impact of study: This study provides new insights on the cellular and systemic level to understand the mechanism of THSWD in the treatment of fractures.