Biologic factors involved in articular cartilage repair and regeneration

A number of factors are implicated in the regulation of articular cartilage metabolism and possible repair. In general, proinflammatory cytokines such as interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-α exert catabolic activities, whereas polypeptide growth factors such as insulin-like growth factors (IGFs), basic fibroblast growth factors (bFGFs), transforming growth factors (TGFs), and bone morphogenetic proteins (BMPs) promote anabolic actions. Some pharmaceutical agents such as dexamethasone, nonsteroidal antiinflammatory drugs, and retinoic acid, as well as matrix components such as fibronectin fragments, chondroitin sulfates, hyaluronan, and decorin have been shown to have chondroprotective and/or chondrotoxic effects. These factors hold promise for new treatment strategies for articular cartilage injury.