The main objective of this Phase I project was to establish a source of serum-free medium suitable for sustained growth of early passage Syrian hamster embryo (SHE) cells. Specific aims included selection of a basal medium supportive of clonal growth in limiting serum concentrations, replacement of serum by selected growth factors and hormones, optimization of supplements by clonal titrations, and comparison of growth characteristics in serum-free and conventional serum-supplemented media. The selected basal medium (DME/F-12) supports clonal growth of secondary SHE cells in 1-percent serum (FBS) without feeder cells. An interim serum-free formulation [DME/F-12, insulin, transferrin, epidermal growth factor, selenium, ascorbic acid, bovine pituitary extract (BPE)L supports clonal growth with 3.8-percent colony-forming efficiency (CFE). Clonal titration and addition/deletion experiments have provided several clues concerning stimulatory and inhibitory factors in FBS. Somatomedin C (IGF-1) and fibroblast growth factor are stimulatory, transforming growth-factor-beta and platelet-derived growth factor are inhibitory, and BPE can replace FBS. Clonal growth (-l-percent CFE) has also been achieved in the absence of both BPE and FBS. Because of its variability, elimination of serum will facilitate standardization of genotoxic testing protocols and studies on the involvement of transforming growth factors in the mechanism of carcinogenesis.
Anticipated Results:An important commercial application of this research will be the development of a custom-made serum-free medium for SHE cells, a system that is extensively used for carcinogen/mutagen screening of new consumer products. Moreover, such a serum-free medium will facilitate basic research on the role of transforming growth factors in carcinogenesis.National Institute Of Environmental Health Sciences (NIEHS)
