Genetic Toxicology: Chromosome Aberration Test in Cultured Mammalian Cells
Chromosome Aberration Test in Cultured CHO Cells and Human Peripheral Blood Lymphocytes (OECD TG 473)
The objective of this assay is to evaluate the test article and its metabolites for their potential to cause chromosome aberrations in cultured mammalian cells. The study design follows the current OECD Guideline for Testing of Chemicals – TG 473, In vitro Mammalian Chromosomal Aberration Test (2014). The assay can be performed in accordance with Good Laboratory Practices.
A preliminary toxicity test may be performed to help design the concentrations. In the main experiment, three analyzable concentrations in duplicate flasks are designed. Cells are exposed to the test article with and without exogenous drug-metabolic enzymes from liver (S9 fraction). Positive control cultures will be treated with Cyclophosphamide (presence of S9) and MMC (absence of S9). Negative control cultures will be treated with vehicle. Cultures are treated for three hours, rinsed with buffered saline and incubated for a total of 18 hours (approximately 1.5 times a normal cell cycle). At an appropriate time, cells receive Colcemid® to accumulate dividing cells in a metaphase-like stage of mitosis. Slides are prepared for analysis and coded. Well-spread metaphase cells with 2n ± 2 chromosomes will be analyzed for chromosome aberrations. At least 300 cells from each concentration, 150 cells from each of the duplicates, are examined.
A positive response shows a concentration-related response and a statistically significant increase in the percentage of cells with aberrations at one or more concentrations over that of the solvent controls. Positive results indicate that the test article induces chromosome aberrations in the cultured cells. A negative response presents no statistically significant increase in the percentage of cells with aberrations. Negative results indicate that, under the test conditions, the test article does not induce chromosome aberrations in the cultured cells. In the case of a negative result a confirmatory experiment is required. In the confirmatory assay, cells are exposed for 18 hours to the test article without exogenous drug-metabolic enzymes. A positive result will not usually need confirmation.
Experiment will start after receipt of signed protocol and the test substance. A draft report will be ready for review within 8-10 weeks after the experimental start date. Documents will be archived for six years.
For further information, to receive a quotation, or to schedule a test, please contact NUCRO-TECHNICS.