Effects of compressive loading on human synovium-derived cells

Compressive stress may be involved in temporomandibular joint (TMJ) synovitis, but its mechanism has not been fully elucidated. We hypothesized that mechanical stress to the synovial cells of the TMJ potentially causes degenerative changes in temporomandibular joint disease. We examined the effect of cyclic compressive loading on three-dimensionally engineered constructs using human TMJ synovium-derived cells in vitro. Human TMJ synovium-derived cells were cultured onto collagen scaffolds, resulting in three-dimensional constructs. Cyclic compression loading was applied to the constructs by means of a custom-designed apparatus. DNA amount, apoptotic cells, and mRNA levels for inflammatory cytokines were analyzed. The protein expression and activity of MMPs were examined. DNA amount or apoptotic cell number was unchanged by loading. MMP-2, -3, and IL-8 mRNA expression was up-regulated by the compression, and both MMP-1 and -3 protein expression and MMP-2 activity were detected. Thus, compression of human TMJ synovium-derived cells appears to modulate inflammatory cytokines.