Demonstration of proficiency of the flow cytometric in vitro micronucleus test as a screening tool for genotoxicity assessment

UKEMS 2025 -- The in vitro micronucleus (IVMN) assay is routinely used at early stages of compound development to investigate a test compound’s aneugenic and/or clastogenic potential [mechanisms for micronucleus (MN) induction]. As test compound is limited at early stages of development, the screening IVMN assay is routinely performed in 96-well plates using human TK6 cells to mimic the design of the standard micronucleus assay using minimal test compound (~5mg). Traditional slide-based manual MN analysis can be labour intensive and time consuming. Flow cytometry can be used to automate analysis of large numbers of cells across multiple concentrations and, additionally, allows analysis of other compound-related effects (such as cytostasis, cellular death and cell cycle arrest) in addition to MN induction. The MicroFlow® kit (Litron Laboratories, US) uses sequential staining to identify MN from late apoptotic and necrotic cells to reduce the likelihood of false-positive results.In this study, human TK6 cells were exposed to known genotoxins and non-genotoxins in the absence or presence of S-9 to establish MN analysis by flow cytometry at Labcorp using the MicroFlow staining kit.