Transforming Growth Factor-β1 in Combination with Fibroblast Growth Factor-2 and Insulin-like Growth Factor-I for Chondrocyte Proliferation Culture and Cartilage Regenerative Medicine

Objective: To investigate the effects of transforming growth factor-β1 (TGF-β1) in combination with fibroblast growth factor-2 (FGF-2) and insulin-like growth factor-I (IGF-I), on the properties of chondrocytes after proliferation culture.Materials and Methods: The chondrocytes were obtained from remnant auricular cartilage during microtia operations and cultured with various growth factors. The proliferation and differentiation of cultured chondrocytes and the risk for malignant transformation of cells were evaluated.Results: A combination of FGF-2, IGF-I, and TGF-β1 was more effective than that of FGF-2 and IGF-I in terms of cell proliferation. Real-time quantitative polymerase chain reaction analysis revealed that FGF-2, IGF-I, and TGF-β1 strongly induced chondrocyte hypertrophy, suggesting that FGF-2, IGF-I, and TGF-β1 combined were inferior to FGF-2 and IGF-I in maintaining permanent cartilage phenotype. There was no significant difference in telomerase activities between cells cultured with FGF-2 and IGF-I and those with FGF-2, IGF-I, and TGF-β1. There was a slight increase in the S phase of the cell cycle in cells cultured with FGF-2, IGF-I, and TGF-β1 compared with those with only FGF-2 and IGF-I. There were also some alterations in the retinoblastoma pathway of the chondrocytes cultured with FGF-2, IGF-I, and TGF-β1.Conclusion: The results indicate that a combination of FGF-2 and IGF-I may be superior to one of FGF-2, IGF-I, and TGF-β1 for permanent cartilage regeneration. These analyses are useful for evaluating the properties of cultured chondrocytes.