A PRACTICAL CYTOGENETIC PROTOCOL FOR IN-VITRO CYTOTOXICITY AND GENOTOXICITY TESTING

In vitro cytogenetics has been established as a valid method for evalu ating the genotoxic potential of chemical agents.(1,2) Armstrong et al (3) have described a simple, quantitative approach to in vitro cytotox icity and genotoxicity testing by using Chinese hamster ovary (CHO) ce lls. This approach can also be sensitive and repeatable in an inter-la boratory setting, a prerequisite for routine testing of compounds susp ected of having genotoxic properties. In the present study, cytotoxici ty was evaluated by the parameter of mitotic index (MI). Genotoxicity is measured by the chromosome aberration (Abs) assay as described by A rmstrong et al(3) using CHO cells. The basic analytic principles propo sed were extended to include human lymphocytes. Sister chromatid excha nge (SCE) analysis was used to establish an additional endpoint. Mitom ycin C (MMC), an established clastogen, was used as the model compound for protocol validation. Dose response curves for MI and Abs in CHO c ells were found to be consistent with those reported by Armstrong et a l.(3) Results from our extended study on lymphocytes and using SCE ana lysis were analogous. Our experience is that this standardized approac h is indeed sensitive and reliable and can serve as a basis for an int er-laboratory testing program.