We intended to check the growth rates and phenotypic markers of chondrocytes in the dedifferentiated cells cultivated in various conditions in order to establish the ideal culture system for implantation.

Culturing rabbit chondrocytes from proximal tibia, we checked the phenotypes at first, second, and third week. Then we cultured the chondrocytes in different circumstances such as monolayer or three dimensional gel in the presence or abscence of TGF-B1, and checked the growth rates and phenotypic markers.

There was no difference in growth rates and mRNA level of type I, type II collagen and aggrecan between the cells cultured in monolayer and three dimensional gel of collagen. However, the responses of the cells to TGF-B1, were quite different between these two groups. In monolayer culture, the expression of type I collagen was depressed by TGF-B1 while the growth rate was markedly increased. Oppositely in three dimensional culture, the mRNA level of type I collagen was markedly increased and the growth rate was completely suppressed by TGF-B1. The expression of type II collagen could be detected only in TGF-B1-treated cells cultured in three dimensional gel for 4 or more days. The mRNA level of aggrecan was also increased by TGF-B1, in the cells cultured in three dimensional gel.

These results suggest that the number of chondrocytes can be efficiently expanded by culturing the cells in monolayer and the phenotypes of chondrocyte can be restored by culturing the cells in three dimensional gel containing TGF-B1. The application of semi-solid gel containing differentiated chondrocytes in physeal implantation should be further evaluated