ICH states, "Systems for automated analysis (image analysis and flow cytometry) can be used if appropriately validated…"

ICH considers assays validated if they meet the criteria as stated by the International Workshop on Genotoxicity Testing (IWGT) in this article. These criteria are:

• Provide % MN-RET, % MN-NCE and % RET.
• Detects both fragments and whole chromosomes.
• Score consistently within and between experiments.
• Understand how known artifacts behave in the system.

In Vivo MicroFlow kits meet all of these criteria.

IWGT also stated that “A number of different flow cytometric-based micronucleus assays have been developed, but at the present time the validation data are most extensive for the flow cytometric method using anti-CD71 fluorescent staining especially in terms of inter-laboratory collaborative data.”

The “anti-CD71” method referred to here is the MicroFlow method.

ICH also states “…each laboratory should determine the appropriate minimum sample size to ensure that scoring error is maintained below the level of animal-to-animal variation.”

Using MicroFlow kits, 20,000 cells are routinely analyzed per sample. This is considered sufficiently large to ensure scoring error is below the level of animal-to-animal variation.

Yes. ICH states, “In case of repeated administrations, attempts should be made to incorporate the genotoxicity endpoints into toxicity studies…”.

The MicroFlow method, requiring very low volumes of blood, makes it easy to integrate into existing studies.

Yes. ICH states, “Rat blood can be used for micronucleus analysis provided methods are used to ensure analysis of the newly formed reticulocytes…and the sample size is sufficiently large to provide appropriate statistical sensitivity…”.

The guideline also indicates that rat peripheral blood can be used for MN assessment as long as MN are measured in the immature erythrocytes (polychromatic erythrocytes/reticulocytes).

MicroFlow kits are available for rat blood and can discriminate between mature and immature erythrocytes using the anti-CD71 antibody.

Yes. ICH states, “Several in vitro mammalian cell systems are widely used and can be considered sufficiently validated: The in vitro metaphase chromosome aberration assay, the in vitro micronucleus assay and the mouse lymphoma L5178Y cell Tk (thymidine kinase) gene mutation assay (MLA). These three assays are currently considered equally appropriate and therefore interchangeable for measurement of chromosomal damage...”

MicroFlow In Vitro Kits use flow cytometry to analyze hundreds of samples in just a few hours. This method supports both attachment and suspension cell lines. Contact us for more information on how In Vitro MicroFlow kits can support your regulatory submissions.