A novel terminal differentiation model of human articular chondrocytes in three‐dimensional cultures mimicking chondrocytic changes in osteoarthritis

This study establishes a cell culture model mimicking the terminal differentiation occurring in osteoarthritic chondrocytes. Normal articular chondrocytes obtained from human knees treated with 5-azacytidine (Aza-C) were harvested 3, 7 and 14 days after treatment. Phenotypic and genetic changes of articular chondrocytes were detected. The results show that mRNA expression of collagen type II, a marker for normal functional articular chondrocytes, was significantly decreased after Aza-C treatment in comparison to the control cultures, while those of collagen type X and ALP, markers for hypertrophic chondrocytes, were significantly increased. Cell size and apoptotic rate of articular chondrocytes showed significant increases compared to the control after 14 days of Aza-C treatment. Terminal differentiation is shown by this model of three-dimensional cultured human articular chondrocytes, which could apply to the studies of the cellular mechanisms of osteoarthritis.