Effects of IGF-I,IGF-II,and PDGF on the proliferation of rabbit articular chondrocytes in culture

The effects of insulin-like growth factor (IGF)-I, IGF-II, and platelet-derived growth factor (PDGF) were examined in cultured chondrocytes derived from rabbit joint cartilage. In addition, the expression of IGF-I receptors on the cultured chondrocytes was detected with anti-IGF-I receptor antibody. IGF-I acted as a growth stimulant, but IGF-II had no effect on cell growth. Increasing the dose of IGF-I beyond 50 ng/ml resulted in decreased growth stimulation. The expression of IGF-I receptors was detected continuously during the culture period. The results also showed that PDGF acted as a growth inhibitor, in contrast to the results of other studies. Further studies are necessary to clarify the precise mechanism of the action of PDGF and the role played by different homo- or heterodimers of PDGF in the proliferation of articular chondrocytes.