Objective To explore the role and mechanism of mechanical stretch in promoting osteogenic differentiation of mouse bone marrow mesenchymal stem cells (BMSCs) via Piezo1. BMSCs were divided into 0%, 3%, 6%, and 12% mechanical stretch intensity groups. BMSCs were divided into 0%, 3%, 6%, and 12% mechanical stretch intensity groups. Cell proliferation was detected by CCK-8, and osteogenic factors (Runx2, Osterix, ALP, and OPN) mRNA were detected by PCR to screen for the optimal stretch intensity. Then, control, mechanical stretch, Piezo1 inhibitor, and mechanical stretch+Piezo1 inhibitor groups were set up separately. After the intervention, ALP staining and ALP activity testing were performed. Observe the formation of calcium nodules with alizarin red staining, and measure the OD570nm value of each group after dissolving the calcium nodules. Piezo1 and TGF-β1, p-Smad2 and Runx2 protein levels were detected by Western blot. Results Compared with 0% mechanical stretch, 3% and 6% mechanical stretch promoted cell proliferation (P<0.05), and the mRNA levels of Runx2, Osterix, ALP, and OPN were significantly increased in the 6% mechanical stretch group (P<0.05). In addition, compared with the control group, the mechanical stretch group showed deeper ALP staining, significantly increased ALP activity, number of calcium nodules, and the proteins of Piezo1, TGF-β1, p-Smad2 and Runx2 (all P<0.05); the Piezo1 inhibitor group showed lighter ALP staining, significantly reduced ALP activity, number of calcium nodules, and the proteins of Piezo1, TGF-β1, p-Smad2 and Runx2 (all P<0.05). Compared with the mechanical stretch group, the mechanical stretch+Piezo1 inhibitor group showed lighter ALP staining, significantly reduced ALP activity, number of calcium nodules, and the proteins of Piezo1, TGF-β1, p-Smad2 and Runx2 (all P<0.05). Compared with the Piezo1 inhibitor group, the mechanical stretch+Piezo1 inhibitor group showed deeper ALP staining, significantly increased ALP activity, number of calcium nodules, and the proteins of Piezo1, TGF-β1, p-Smad2 and Runx2 (all P<0.05). Conclusion Mechanical stretch may up-regulate the expression of the TGF-β1/Smad2 signaling pathway through Piezo1, and promotes the proliferation and osteogenic differentiation of BMSCs. |