Figure 4.

Effect of high-frequency near-infrared diode laser irradiation on levels of secreted matrix metalloproteinases (MMPs) in NHAC-Kn cells. The chondrocytes were treated with interleukin (IL) -1β (10 pg/mL) and laser irradiated (0, 8 J/cm²) for 20 h; the culture medium was collected and used for enzyme-linked immunosorbent assay (ELISA). Secreted protein levels of (A) MMP-1 and (B) MMP-3 are represented as mean ± SEM of three independent experiments (n = 3). * p < 0.05 compared to the IL-1β group.