Dose-Dependent Effects of Transforming Growth Factor-beta1 on Cell Proliferation and Matrix Synthesis in Relation to the Degree of Chondrocyte Dedifferentiation in Monolayer Culture

Kim, Tae Gyun; Lee, Myung Chul; Seong, In Ho; Kim, Sung Tae; Yong, Hee Joong; Sang, Hoon Park; Park, Chul; Seong, Sang Cheol

Abstract

Transforming growth factor-beta1(TGF-beta1) has been suggested to be a useful growth facto. that could maintain the phenotypic characteristics of cultured chondrocytes. We performed this study to investigate the dose-dependent effects of TGF-beta1 on cell proliferation and matrix synthesis in relation to the degree of chondrocyte dedifferentiation in monolayer culture. Chondrocytes were isolated from the articular cartilage of distal femur of neonatal Sprague-Dawley rats and were cultured in monolayer. When the cell population reached 70-80% of confluence, the cells were subcultured successively for 6 weeks for the following studies. Every weak, the dose dependent effects of rhTGF-beta1 (0ng/ml ,1ng/ml, 5ng/ml, 10ng/ml, 20ng/m1) on DNA synthesis, proteoglycan synthesis and collagen synthesis were evaluated by 3H-thymidine incorporation, 35S-sulfate incorporation and 3H-proline incorporation respectively. The DNA synthesis decreased with time of culture. The DNA synthesis was significantly decreased by the addition of rhTGF-beta1 at all concentrations. The dose-dependent inhibitory action was most prominent at initial 3 weeks. Proteoglycan synthesis was in the highest level at the second week and markedly decreased after 2 weeks. At 2 weeks, TGF-beta1 treatment increased the proteoglycan synthesis at all concentrations and this stimulatory effect was prominent at the concentrations of 5ng/ml and 10ng/ml. There was no significant difference in the level of collagen synthesis during the whole experimental period. TGF- beta1 treatment increased collagen synthesis at all concentrations and this stimulatory effect was prominent at the concentrations at 5ng/ml and 10ng/ml. The results of this study suggest that if the cultured chondrocytes treated by TGF-beta 1 are used for transplantation, the time for TGF-beta1 treatment and transplantation to be recommended is before 3 weeks and the beneficial concentration of TGF-beta1 is 5ng/ml to 10 ng/ml for the maintenance of the phenotypic properties.