Effects of Clematis chinensis Osbeck mediated by low-intensity pulsed ultrasound on transforming growth factor-β/Smad signaling in rabbit articular chondrocytes.

Purpose: Clematis chinensis Osbeck (CCO) is an essential herb that has been shown to promote the biological functions of cartilage cells. In this study, we aimed to explore whether and how low-intensity pulsed ultrasound (LIPUS) enhanced CCO delivery into chondrocytes and stimulated biological activity in vitro.

Methods: Chondrocytes were isolated from knee articular cartilage of 2-week-old rabbits and treated with LIPUS plus CCO or recombinant transforming growth factor beta 1 (TGF-β1; 0.5 ng/mL), with or without anti-TGF-β1 antibodies (10 μg/mL), for 3 days. Cell proliferation was assessed by Cell-Counting Kit-8 assays. Immunocytochemistry, western blotting, and quantitative polymerase chain reaction were applied to detect the expression of type II collagen and some molecules in the TGF-β1 signal pathway.

Results: LIPUS plus 0.1 mg/mL CCO solution promoted chondrocyte proliferation and type II collagen and TGF-β1 expression synergistically in vitro (P < 0.05). In addition, treatment with anti-TGF-β1 antibodies blocked this effect (P < 0.01), but not completely. CCO plus LIPUS also showed more enhanced effects on promoting TGF-β receptor II and Smad2 signaling and reducing Smad7 signaling than either intervention separately (P < 0.05).

Conclusions: CCO plus LIPUS promoted extracellular matrix deposition by accelerating the TGF-β/Smad-signaling pathway in chondrocytes.