Replacement of serum by hormones permits growth of cells in a defined medium

Abstract

MOST cell cultures require the addition of serum to synthetic media for their maintenance and growth, and we believe that the primary role of the serum is to provide hormones¹. We have been led to this hypothesis by a series of experiments showing that serum depleted of certain hormones no longer supports growth of cells, unless the medium is supplemented with the hormones that were removed^2–4. Clear evidence for the validity of this hypothesis has not yet been obtained because it is difficult to grow cells in the absence of serum. Recently, however, we have succeeded in growing an established rat pituitary cell line, GH₃, in a defined serum-free medium supplemented with physiological concentrations of four hormones together with the iron transport protein, transferrin. Preliminary investigation shows that serum-free medium supplemented with hormone will also support the growth of several other cell lines.