Factors controlling the proliferative rate, final cell density, and life span of bovine vascular smooth muscle cells in culture.

Abstract

Low density vascular smooth muscle (VSM) cell cultures maintained on extracellular-matrix (ECM)-coated dishes and plated in the presence of either plasma or serum will proliferate actively when serum-containing medium is replaced by a synthetic medium supplemented with 3 factors: high density lipoprotein (HDL, 250 .mu.g protein/ml); insulin (2.5 .mu.g/ml) or somatomedin C (10 ng/ml); and fibroblast growth factor (FGF, 100 ng/ml) or epidermal growth factor (EGF, 50 ng/ml). The omission of any of these factors from the synthetic medium results in a lower growth rate of the cultures, and in a lower final cell density once cultures reach confluence. When cells are plated in the total absence of serum, transferrin (10 .mu.g/ml) is required to induce optimal cell growth. The effects of substrate and medium supplements on life span of VSM cultures were analyzed. Cultures maintained on plastic and exposed to medium supplemented with 5% bovine serum underwent 15 generations. When maintained on ECM-coated dishes, the serum-fed cultures had a life span of at least 88 generations. When cultures were maintained in a synthetic medium supplemented with HDL and either FGF or EGF, an effect of the substrate on the tissue culture life span was observed. Cultures maintained on plastic underwent 24 generations; those maintained on ECM-caoated dishes were passaged repeatedly for 58 generations. The influence of the ECM-substrate is demonstrated not only in promoting cell growth but also in increasing the longevity of the cultures.