Flow cytometric 96-well microplate-based in vitro micronucleus assay with human TK6 cells: protocol optimization and...

Area of Science:

• Toxicology
• Genetics
• Biotechnology

Background:

• The in vitro micronucleus (MN) assay is crucial for genotoxicity testing.
• Conventional MN assays can be resource-intensive.
• Automated, miniaturized approaches are needed to improve efficiency and reduce compound usage.

Purpose of the Study:

• To optimize and assess the transferability and reproducibility of a miniaturized, automated in vitro MN assay.
• To evaluate the assay's sensitivity and specificity for genotoxicity detection.
• To refine parameters for improved assay performance, particularly specificity.

Main Methods:

• Utilized a 96-well plate format combining compound exposure, processing, and flow cytometric analysis.
• Optimized protocol through a training phase with collaborating laboratories.
• Assessed assay performance using a diverse set of 32 chemicals (genotoxicants and non-genotoxicants) across four sites.
• Measured MN frequencies and cytotoxicity endpoints (relative survival, ethidium monoazide staining).

Main Results:

• The assay demonstrated good transferability and reproducibility across multiple laboratories.
• Sensitivity ranged from 82-98% and specificity from 86-97%, depending on parameter selection.
• Specificity was enhanced by basing top concentration selection on relative survival and ethidium monoazide-positive events.
• The 96-well format significantly reduced compound consumption compared to conventional methods.

Conclusions:

• The miniaturized, automated in vitro MN assay is a robust and transferable method for genotoxicity testing.
• Flow cytometry integration provides high information content, mitigating false positives due to toxicity.
• This optimized assay offers an efficient and reliable alternative for toxicological screening.