The effects of a single acute load on an equine articular cartilage explant system and further studies on the ability of glucosamine and chondroitin sulfate to inhibit cytokine-induced cartilage degradation

Trauma to a joint can initiate of equine osteoarthritis (OA) by damaging the cartilage and increasing the synthesis of catabolic molecules. Oral treatment of OA is also becoming more popular within the equine industry. Glucosamine (GLN) and chondroitin sulfate (CS) may slow cartilage degeneration associated with OA and improve lameness in the horse. Equine articular cartilage explants were used to evaluate the effects of loading (15 or 30 MPa) compared to cytokine-stimulation (LPS). LPS-treated explants had the highest nitric oxide (NO) and prostaglandin E₂ (PGE₂) production over all treatments, while loading explants at 30 MPa resulted in the highest proteoglycan (PG) release, and second highest keratan sulfate (KS) degradation and PGE₂ production. Explants loaded at 15 MPa did not differ from the control in NO, PG, or PGE ₂ production, but had the highest KS loss of any treatment. The same explant system was used to evaluate if GLN (0.2–0.5 mg/ml) in combination with CS (0.125 mg/ml) are effective in inhibiting cytokine-induced cartilage degradation. NO and PGE₂ production and matrix metalloproteinase (MMP) activity were evaluated. NO production was lowered from 0.3 to 0.5 mg/ml GLN, while PGE₂ production was decreased at 0.4 and 0.5 mg/ml. Matrix metalloproteinase-9 activity was decreased at 0.5 mg/ml and tended to be decreased at 0.4 mg/ml.