ABSTRACT
In monolayer culture, articular chondrocytes are well known to proliferate and dedifferentiate by seum and transforming growth factor-beta(TGF-beta). These dedifferentiated cells regain the ability to express type II collagen in alginate bead culture. In this study, the effects of human serum and TGF-beta on the proliferation and phenotypical change of human chondrocytes were examined in both monolayer and alginate bead culture. Proliferation was measured by 3H-thymidine incorporation and cell counting, chondrocytic phenotype by Western blot analysis of type II collagen expression, and proteoglycan synthesis by dimethylmethylene blue assay. Both human serum and TGF-beta synergistically increased the proliferation of chondrocytes in monolayer culture. Human serum had effect to maintain the type II collagen expression, even with enhanced level, in monolayer culture and showed redifferentiation in alginate culture, similar to fetal bovine serum control. TGF-beta enhanced the production of proteoglycan in monolayer culture. In conclusion, the present study demonstrated that human serum and TGF-beta could be used as potent additives to increase chondrocyte proliferation and maintain its phenotype.