Isolation of mammalian cell autotrophs able to grow indefinitely in protein-free chemically defined medium

A selection procedure is described for obtaining cell variants, called autotrophs, which are able to grow from low-molecular-weight metabolic precursors in the absence of macromolecules and serum replacement factors. These autotrophs can readily be isolated from a variety of cell lines, including normal (nontransformed) NIH3T3 cells, their spontaneous or tre oncogene-transfected tumor-producing derivatives, and HeLa cells. Tre-transfected autotrophs grew faster than their normal or spontaneously transformed counterparts, and much faster than autotrophic HeLa cells. Chinese hamster autotrophs, which have now been cultured for nearly two years, grow with a population doubling time of 30 h.