Survival of 3T3-L1 cells induced by fibroblast growth factor depends on cell density and adhesion to the substratum.

The effects of cell contacts and the attachment of cells to the substratum on growth-factor-induced survival of 3T3-L1 cells were investigated to clarify their involvement in the maintenance of cell viability. When 3T3-L1 cells in low-density cultures or in high-density cultures were harvested with EDTA solution and cultured in the absence of calf serum, almost all cells from the low-density cultures lost viability 24 h later. However, about 15% of the cells harvested from high-density cultures survived for 24 h in the absence of calf serum. Addition of calf serum also enhanced the survival of cells from high-density cultures to a much greater extent than that of cells from low-density cultures. Addition of fibroblast growth factor enhanced the survival of cells, especially in the case of cells from high-density cultures. However, epidermal growth factor and platelet-derived growth factor failed to enhance survival. Coating of cultures dishes with vitronectin slightly enhanced cell survival. Addition of fibroblast growth factor markedly enhanced the survival of cells on the dishes coated with vitronectin or with fibronectin, but not on the dishes coated with heat-denatured bovine serum albumin. These results suggest that fibroblast growth factor promotes survival of 3T3-L1 cells, depending on cell to-cell contacts during prior culture and on the adhesion of cells to the substratum.