Effect of cholesterol and growth factors on the proliferation of cultured human skin fibroblasts. 
A cholesterol-deficient growth medium for human skin fibroblasts was prepared by adding to Eagle's Minimum Essential Medium a bovine serum treated with ultracentrifugation to remove bulk lipoproteins followed by silicic acid adsorption to remove residual lipoproteins and cholesterol.  Cell growth was slow, but the daily cell doublings could be increased by 76% by including 7.5 micrograms purified cholesterol/ml in the medium.  Cell growth in cholesterol-deficient culture medium could be increased to that seen with medium containing 15% untreated fetal bovine serum by the inclusion of the following growth factors: epidermal growth factor (EGF), cortisol, non-essential amino acids, insulin, transferrin and selenium.  Cholesterol increased the proliferation of these rapidly-growing cultures by 19%.  No effect of cholesterol was observed in transformed L-cell mouse fibroblasts.