Further studies on a tryptose based serum-free medium for human diploid fibroblasts

A serum-free medium containing Eagle's MEM, transferrin, tryptose and dexamethasone as active ingredients was able to support the growth of human diploid fibroblast cells for over 20 population divisions. However, the cells stopped growing at an earlier age and the growth rate was half that of cells grown in Eagle's MEM + 10% calf serum. The results of efforts to improve this medium show that: the addition of insulin to the medium is not required, but dexamethasone is absolutely essential; there is an antagonism between adenosine and cytidine which is inhibitory for growth; the addition of extra amino acids such as arginine, lysine, methionine, tryptophane, phenylalanine, isoleucine, cystine, serine or hydroxyproline is inhibitory for growth.