Fig. 5

Inhibition of integrin-mTOR pathway suppressed TGF-β1-induced chondrogenesis of BMSCs and the treatment effects of LIPUS. a Western blot analysis demonstrate that GRGDSP inhibited β1 integrin expression in a dose-dependent manner. b Western blot results show that Rapamycin inhibited the activation of mTOR in a dose-dependent manner. c Immunohistochemical staining for COL2 of BMSCs cultured with TGF-β1-treated medium in control, LIPUS, GRGDSP, GRGDSP + LIPUS, Rapamycin, and Rapamycin + LIPUS groups. Images acquired by microscopy on day 10; scale bars = 25 μm. d Western blot analysis of COL2, aggrecan, SOX9, COL1, integrin β1, and p-mTOR with β-actin as a loading control in BMSCs treated with TGF-β1 with or without LIPUS stimulation following GRGDSP or Rapamycin treatment. e–j Statistics of the western blot results of COL2, aggrecan, SOX9, COL1, β1 integrin, and p-mTOR. The ratio between the target and β-actin was used to normalize the data for comparison. The values are mean ± SEM of triplicate experiments. n = 6; *P < 0.05. COL1 collagen type-I, COL2 collagen type-2. LIPUS low-intensity pulsed ultrasound, mTOR mechanistic target of rapamycin, SOX9 SRY-related high mobility group-box gene 9, TGF transforming growth factor