LIPUS promotes synthesis and secretion of extracellular matrix and reduces cell apoptosis in human osteoarthritis through upregulation of SOX9 expression.

Increasing studies have illustrated that low-intensity pulsed ultrasound (LIPUS) has a therapeutic effect in experimental animal models of osteoarthritis (OA). However, the function of the LIPUS on human chondrocytes of OA remains unclear. The aim of the current study was to observe the effect and explore the mechanism of LIPUS treatment on proliferation, apoptosis, and extracellular matrix (ECM) production of chondrocytes in vitro. Results showed that LIPUS stimulation at 30, 60, and 90 mW/cm2 intensities markedly inhibited the apoptosis of chondrocytes compared with the 0 mW/cm2 intensity; however, the effect of LIPUS stimulation at 0, 30, 60, and 90 mW/cm2 intensities on the proliferation of chondrocytes had no significant difference. Furthermore, the mRNA and protein levels of COL2A1 and ACAN were upregulated in chondrocytes treated with LIPUS stimulation at 30, 60, and 90 mW/cm2 intensities. The concentration of COL2A1 and ACAN in supernatants of chondrocytes in the 30, 60, and 90 mW/cm2 groups were obviously higher than those in the 0 mW/cm2 group. In addition, activation of SOX9 mRNA and protein expression were observed in the 30, 60, and 90 mW/cm2 groups compared with the 0 mW/cm2 group. In summary, our data demonstrated that LIPUS promotes ECM synthesis and secretion and reduces apoptosis of human OA by activation of SOX9, indicating LIPUS might bea promising therapy for the treatment of OA.