Osteoblasts from the sclerotic subchondral bone downregulate aggrecan but upregulate metalloproteinases expression by chondrocytes. This effect is mimicked by interleukin-6, -1β and oncostatin M pre-treated non-sclerotic osteoblasts

These results demonstrate that SC OA subchondral osteoblasts could contribute to cartilage degradation by stimulating chondrocytes to produce more MMP and also by inhibiting AGG synthesis.