[Effect of growth factors on cell proliferation and matrix synthesis in cultured human chondrocytes]

In reconstructive surgery, autologous cartilage grafting is commonly performed to reconstruct skeletal defects. Because of the limited supply of fresh autologous cartilage, many investigators concentrate on the in vitro production of cartilage tissue. Several growth factors regulate the metabolism and activation of cartilage cells. The aim of our investigation was to characterize the influence of transforming growth factor (TGF)-beta, epidermal growth factor (EGF), and basic fibroblast growth factor (bFGF) on the proliferation and matrix synthesis of human nasal septal chondrocytes. The isolated cells were cultured in monolayer and in agar. The biological effects of the growth factors were assessed by determining the total protein and proteoglycan synthesis and cell proliferation. We observed an increase of the proliferation rates when the different growth factors were added. Greater stimulation was produced by bFGF than by EGF. Adding all growth factors together produced a fivefold increase in the proliferation activity of the cells. The effects were enhanced by factors present in fetal calf serum. TGF-beta caused dose-dependent stimulations of total protein as well as glycosaminoglycan synthesis in chondrocytes cultured in monolayer and agar. The stimulating effect of TGF-beta on matrix synthesis was greater for chondrocytes cultured in agar than for chondrocytes cultured in monolayer. No stimulatory effects of bFGF on the matrix synthesis were observed in any of both culture conditions. We can conclude that the conditions for cartilage cultivation can be optimized by employing growth factors.