Continuous culture of rat C6 glioma in serum-free medium.

Abstract
Serum-free culture conditions for the serial propagation of the C6 glioma cell line are described. The growth rate, saturation density and morphology of these cells are equivalent to those of their serum-grown counterparts when cultured in a 3:1 mixture of Dulbecco''s modified Eagle''s medium and Ham''s medium F-12 supplemented with trace elements, insulin, transferrin, fibroblast growth factor, linoleic acid complexed to fatty acid-free bovine serum albumin and a serum-spreading factor (SSF) partially purified from human plasma. The requirement for SSF in the medium can be satisfied by preincubating the tissue culture dishes with SSF. Tissue culture dishes sequentially pretreated with poly-D-lysine and purified cold insoluble globulin will also substitute for this requirement. The fatty acid-free bovine serum albumin/linoleic acid complex increases the growth rate of these cells but has no appreciable effect on their morphology, saturation density or ability to grow with repeated subculture. The growth stimulation caused by this complex appears to be dependent on the fatty acid, as the fatty acid-free bovine serum albumin alone has no effect on the growth rate. Linoleic acid is cytotoxic in the absence of bovine serum albumin and the fatty acid-free bovine serum albumin prevents this toxicity. Other fatty acids including oleic, arachidonic and palmitic only partially substitute for the growth-promoting effect of linoleic acid.