Mechanical stimulation regulates differentiation of bone marrow stem cells by modulating miR-140-5p via TGFβ1/Smad2 signaling pathway

Abstract Background: Osteoporosis is a common progressive bone disease that drastically impairs patient health, independent mobility, and quality of life, and there is an urgent need for improved preventive and therapeutic strategies. A shift in bone marrow mesenchymal stem cell (BMSC) differentiation from osteogenic to adipogenic may contribute to disease pathogenesis. Mechanical stress on BMSCs is reported to promote osteogenesis, so we examined the effects of mechanical stimulation on BMSC differentiation and associated signaling pathways.Methods: A sinusoidal tensile stress loading device was developed and examined effects of mechanical (stretch) stimulation on cultured BMSC (isolated from Sprague-Dawley rats) phenotype under osteogenic and adipogenic culture conditions. Osteogenic differentiation of BMSCs was assessed by alkaline phosphatase (ALP) staining and expression of Runx2 and BMP2, while adipogenic differentiation was evaluated by oil red O staining and expression of PPARγ and C/EBPα.Results: It demonstrated that appropriate mechanical stimulation could promote osteogenic differentiation of BMSCs and inhibit differentiation into adipocytes. The mechanic stimuli could inhibit the expression of miR-140-5P in BMSCs, and the overexpression of miR-140-5P inhibited the osteogenic differentiation, whereas the inhibition of miR-140-5P promoted the osteogenic differentiation. Further, both mechanical stimulation and miR-140-5p knockdown promoted TGFβ1/Smad2 signaling, while miR-140-5p overexpression downregulated TGFβ1/ Smad2 signaling.Conclusions: Appropriate mechanical stimulation promoted osteogenic differentiation and inhibited the adipogenic differentiation of BMSCs by lowering miR-140-5p expression, which in turn upregulates the TGFβ1/Smad2 signaling pathway. Our results provide a foundation for the development of effective strategies to promote bone remodeling, thereby lowering the burden of osteoporosis.