Biomechanics of articular cartilage degraded with MMP-1 and MMP-9 mimicking early-stage knee OA

Pathologically, enzyme mediated damage by matrix-metalloproteinases (MMPs) to articular cartilage is one of the early signs of the debilitating disease–osteoarthritis (OA). The dysregulation of osteoarthritic cartilage is often originated by two MMP subfamilies, MMP-1 and MMP-9. Hence, this study investigated the biomechanical properties of degraded cartilage to understanding the mutual effect of MMPs-1 and 9 in the context of early onset OA. Young’s modulus and peak load of the tissue under indentation were compared between the control and degraded cartilage explants. As compared with cartilage degradation with either MMP-1 or MMP-9, the results show 19% reduction in Es and peak load for the cartilage degraded combinedly with the two enzymes in a 1:1 ratio. This elucidates the effect of MMPs on articular cartilage in early-stage OA and will help developing therapeutic interventions to prevent OA.