"adhesion rates and chondrocyte phenotype in monolayer cultures under the influence of collagen type ii and igf-i "

when grown in monolayer culture at low density and with the addition of serum, cartilage cells dedifferentiate or are overgrown by fibroblast-like cells. the aim of this study was to optimize the cultivation of chondrocytes in monolayer culture and to slow down their transformation or their overgrowth by fibroblast-like cells. the interaction between chondrocytes and cartilage-specifc matrix is mediated largely by the β1 subfamily of integrin receptors. this interaction can be regulated or synergized by growth factors, such as igf-i, which stimulates many chondrocyte functions.for this reason isolated chondrocytes of cartilage anlagen from 17- day old mouse embryos were grown on collagen type ii-coated substrates with or without the addition of igf-i (insulin like growth factor-i) using this model chondrocytes grown on collagen type ii with or without igf-i maintained their round phenotype until the end of cultivation. the neutral red assay revealed that chondrocytes cultivated on collagen type ii in the presence of exogenous igf-i, showed a significantly higher density of chondrocye adhesion from the beginnig of cultivation onwards in comparison to chondrocytes cultivated on collagen type ii without igf-i treatment. the cartilage-specific surface receptors (integrins of the β1- group) could also be demonstrated on the membrane of these cells. chondrocytes cultivated on plastic with or without treatment with igf-i, resulted in mixed cultures consisting of fibroblast-like cells and round chondrocytes as observed from the beginning of cultivation onwards. after a 3 to 5 culture period, flat fibroblast-like cells predominated.hence, collagen type ii and igf-i prevent chondrocyte dedifferentiation to fibroblastike cells and this model allows a pure chondrocyte culture.