Replicative senescence occurs when normal somatic cells stop dividing. Senescent cells remain viable, but show alterations in phenotype, e.g. altered expression of matrix metalloproteinases ( MMPs ); these enzymes are known to be involved in cartilage destruction. It is assumed that cells deplete their replicative potential during aging, and age is a major risk factor for osteoarthritis (OA). Therefore, we hypothesized that chondrocytes in aging or diseased cartilage become senescent with associated phenotypic changes contributing to development or progression of OA. SPEX6770 全自動冷凍研磨機 SPEX6870 全自動冷凍研磨機 SPEX6970EFM 冷凍研磨機