Therapeutic Ultrasound Modulates Cell Proliferation and Proinflammatory Cytokine Levels in Osteoarthritic Chondrocytes

The development and progression of osteoarthritis (OA) are believed to involve inflammation. This study aimed to investigate the effects of applying therapeutic ultrasound (US) to human osteoarthritic chondrocytes in continuous and pulsed modes on cell proliferation and proinflammatory cytokine levels. Human osteoarthritic chondrocytes (HC-OA 402OA-05a) were proliferated in appropriate media and then seeded into culture plates. The plates were grouped and exposed to underwater continuous, pulsed and control US at 0.1 W/cm² and 1 MHz for 10 min daily for 10 days. Cell viability/proliferation was assessed using the MTT assay, total protein was measured by ELISA and cytokine levels per protein were determined. Cells were photographed using microscopic analysis. Both continuous and pulsed US groups showed a significant increase in viability compared to the control group. No significant difference was found between the continuous and pulsed US groups for IL-1β, TNF-α and IL-6 levels. Both groups showed significant cytokine reduction compared to the control group. For IL-17 and IL-32 levels, both US groups had reduced cytokine levels compared to the control group, but the results were not significant. Underwater US at 0.1 W/cm² and 1 MHz stimulated cell proliferation and reduced proinflammatory cytokine levels in osteoarthritic chondrocyte cell cultures. This study extensively focused on proinflammatory IL levels, and the meaningful results may inspire future in vivo/in vitro studies. While adapting in vitro data to in vivo conditions poses challenges, our results could guide future in vivo studies and clinical applications.