ABSTRACT
Osteoarthrosis (OA) ensues as a result of perturbations in chondrocyte metabolism. The regulation of chondrocytes in OA is under the control of events occurring in cartilage itself, but may be also amplified by the interaction of exogenous factors (that is, cytokines) with cartilage that potentially alter the phenotypic expression of the cells. In OA, a number of factors may alter this steady state, resulting in changes in proteoglycan concentration. Fetal bovine serum is required for the maintenance of proteoglycan steady-state metabolism in bovine cartilage explant cultures. Insulin-like growth factors have been shown to be the major component of fetal calf serum responsible for up-regulating proteoglycan synthesis. Immobilization causes significant alterations in the composition of articular cartilage, most notably in the loss of chondrocytes which is frequently accompanied by a decrease in cartilage metachromasia. Changes in the nutritional pathway via synovial fluid are compromised in compressive immobilization models of cartilage degeneration.
