Chondrocyte senescence and osteoarthritis : role of oxidized LDL-induced oxidative stress

Although epidemiologic studies have shown that age is the chief risk factor for osteoarthritis (OA), the relationship between aging and the development of OA has not been completely understood yet. However, accumulating evidences in vivo and vitro have shown that the development of OA is, at least in part, attributable to the age-related chondrocyte senescence. This review focuses on how chondrocyte senescence affects the articular cartilage degeneration and how oxidative stress affects the chondrocyte senescence. Further, I would like to introduce our hypothesis that oxidized low-density lipoprotein, which is the most important molecule causing atherosclerosis, is involved in the pathogenesis of OA by playing a role as an oxidative stressor. It is interesting that even though mitotically inactive, senescent cells are far from being biologically inert. Many genes in senescent cells display higher expression levels that do not merely correlate with cell cycle arrest. Chondrocyte senescence is associated with an increased production of inflammatory mediators and matrix degrading enzymes characteristic of the senescent secretory phenotype. Age-related oxidative stress and damage may play a central role in cartilage aging through modulation of cell signaling pathways that regulate anabolic and catabolic activity