Hamster Embryo Cell in Vitro Carcinogenesis Bioassay

Hamster Embryo Cell in Vitro Carcinogenesis Bioassay 

In traditional experiments with the hamster cell clonal assay, primary cultures were prepared from 12- to 14-day-old embryos as needed for each experiment. To enhance plating efficiency, small numbers of cells varying from about 300 to 1000 per dish were seeded onto a sparse lawn of previously X-irradiated feeder cells. Initially, feeder cells were usually from rats, although hamster cells have been used more recently. The cultures were then treated with chemicals for periods of time that varied from a few hours to 8 days, and were then examined for toxicity and transformation. 

In our laboratory, factors other than the selection of susceptible populations of cells could be controlled to optimize transformation of hamster embryo cells and increase the reliability of the bioassay. All batches of culture medium, plastic vessels, and fetal calf serum were pretested before routine use. Primary cells were planted at a high density (1.3 X 10 /cm ) and cultured for no longer than 2-3 days to minimize the number of cell divisions, since susceptibility to transformation appeared to decrease as the number of cell divisions increased. With certain carcinogens, apparently requiring further metabolic activation 

A standard procedure was devised for further evaluating the system by testing a large number of known carcinogens and noncarcinogens. Results with most of these have been reported elsewhere. 

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