In vitro model of equine cartilage degradation; using cartilage pellets differentiated from bone marrow-derived mesenchymal stem cells.

The self-renewal capacity of chondrocytes in osteoarthritis (OA) joints is limited, and mesenchymal stem cells (MSCs) are crucial in disease treatment. This study established an OA model from equine bone marrow-derived mesenchymal stem cells (eBMSCs). The eBMSCs were cultured and differentiated into chondrocytes to generate cartilage pellets, which were induced for 7 d with inflammatory cytokines, interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) to mimic OA conditions. Treated culture medium was collected to estimate enzyme activity (MMP-2, MMP-3, and MMP-9) using zymography, and the cartilage pellets were collected to estimate both anabolic gene (COL2A1) and catabolic gene expression (MMP2, MMP3, and MMP9) using qRT-PCR. Cartilage degradation was observed when induced with IL-1β + TNF-α on cartilage pellets. IL-1β + TNF-α decreased the expression levels of COL2A1 and MMP2 genes, and enhanced their enzymatic activities, while Alcian blue-positive glycosaminoglycan in cartilage pellets induced by IL-1β + TNF-α groups decreased. These results suggested that IL-1β + TNF-α induced on cartilage pellets from eBMSCs could be used as an in vitro OA model in horses.