The in vitro Micronucleus Assay (MNA) is a mutagenicity test system used for the detection of chemicals that induce the formation of small membrane-bound DNA fragments, such as micronuclei in the cytoplasm of interphase cells. These micronuclei may originate from acentric fragments chromosome fragments lacking a centromere or whole chromosomes that are unable to migrate with the rest of the chromosomes during the anaphase of cell division. The assay thus has the potential to detect the activity of both clastogenic and aneugenic chemicals.
Micronuclei can also be induced by radiation exposure. The in vitro MNA is commonly used for genotoxicity and genomic damage studies. This test can also be used for the selection of compounds. In our laboratory, this test is carried out in vitro using Chinese Hamster Ovary (CHO) cells. Like the other screening tests, the in vitro MNA offers cost-effective, quicker information for early phase decision making.
The in vitro MNA has been widely evaluated and an OECD guideline is in preparation (2008).
