Melatonin stimulates extracellular matrix formation in human articular cartilage chondrocytes

Abstract

The articular cartilage present in joints is permanently subjected to physical stress, thus producing injuries and consequently pain. Chondrocytes are responsible for repairing this damage, but often the reparation tissue is inadequate. The application of melatonin to human articular chondrocytes may be a better solution, by generating a good extracellular matrix. Human chondrocytes were assayed in the presence of melatonin, demonstrating that these cells generate more extracellular matrix indicated by the increased Alcian blue staining. This effect of melatonin was concentration- dependent and presented a pD2 value of 6.8 ± 0.1 (n=5). Melatonin also significantly promotes the production of collagen II quantified by western-blot analysis. The effect of melatonin on the collagen II production is also concentration-dependence, with a pD2 value of 6.9 ± 0.2 (n=5). In contrast, melatonin had little effect on the collagen X. The antagonistic study by its non-selective membrane receptor blocker luzindole or its MT2 specific blocker DH-97 identified that these actions of melatonin are mediated by melatonin membrane receptors, mainly by MT2. In summary, melatonin stimulates the production of extracellular matrix and collagen II in chondrocytes and these actions may have significantly clinical implications since it may benefit the autologous chondrocyte transplantations, the only way to maintain and repair the damaged cartilage.