Pre-validation of Tissue Specific Micronucleus Assay for Genotoxicity Testing

DESCRIPTION (provided by applicant): Safety assessment of any new product for human use requires genotoxicity testing to insure that the product is not carcinogenic. Current genotoxicity assays are based on bacterial or non-human cell systems. Such tests are sensitive but give very low specificity (high rate of false positive results). Hence important new chemicals (possibly life-saving drugs) may be eliminated from further development. Animal systems, e.g., rodents, are also used; however, beginning in 2009, legislation in Europe will prevent manufacturers from marketing cosmetics products that have been tested using animals. Given today's global economy, this legislation will directly affect the vast majority of US companies. Finally, for topically applied dermatologic or cosmetic materials, a test which determines genotoxicity to the skin that utilizes a system with inherent metabolic activity would be optimal. The overall goal of this proposal is to develop a skin specific genotoxicity assay. An in vitro highly differentiated skin equivalent tissue will be used to accurately determine the genotoxicity following topical exposure. Based on significant preliminary results, it is likely that this research will result in a human in vitro, skin-specific micronucleus (INVSSMN) assay which will replace current in vitro and animal-based genotoxicity tests. The INVSSMN test will overcome the low levels of specificity of current test methods and avoid animal welfare issues. The specific aims of the Phase I proposal are to: (1) evaluate the INVSSMN assay for a battery of 10 known genotoxins and 5 non-genotoxic chemicals; (2) evaluate INVSSMN assay for a battery of 10 genotoxic chemicals that are known to require metabolic activation to become mutagens; (3) investigate reproducibility of reconstructed skin genotoxicity test; and (4) automate analysis and scoring. Safety assessment of all new products for human use requires a genotoxicity testing to insure that product is not carcinogenic. Current methods are not tissue and human specific which results in extremely low level of specificity and elimination of important substances from further development. We will develop skin-specific micronucleus assay by utilizing in vitro human reconstructed skin model to overcome low levels of specificity of current test methods and avoid animal welfare issues.