Fig. 4

LIPUS promoted TGF-β1-induced chondrogenesis of BMSCs. a Immunocytochemistry staining of COL2 in BMSCs cultured with 10 ng/ml TGF-β1-treated medium after LIPUS stimulation at four intensities on days 5 and 10. Images were acquired using a microscope; scale bars = 25 μm. b Western blot analysis of COL2, aggrecan, SOX9, and COL1 with β-actin as a loading control. c Statistics of the western blot results of COL2, aggrecan, SOX9, and COL1. The ratio between the target and β-actin was used to normalize the data for comparison. Values are the mean ± SEM of triplicate experiments. n = 4; *P < 0.05. COL1 collagen type-I, COL2 collagen type-2. LIPUS low-intensity pulsed ultrasound, SOX9 SRY-related high mobility group-box gene 9, TGF transforming growth factor