The mammalian cell micronucleus test (MNT) is used to determine if a compound is genotoxic to cells in culture by evaluating the presence of micronuclei. The test can be performed in primary human peripheral blood lymphocytes (HPBLs) or established cell lines, such as Chinese hamster ovary (CHO) or TK6 cells.

Screening and Regulatory Support

  • Cultures are incubated with several concentrations of the test compound for three to four hours in the presence and absence of metabolic activation (S9) and for 21 to 24 hours in the absence of S9.
  • A positive outcome is characterized by a statistically significant, dose-dependent increase in micronucleated cells that exceeds historical negative control limits.

When to Perform

  • Screening
  • IND-enabling
    • As part of the ICH S2(R1) standard battery
  • REACH requirement
    • As part of Annex VIII testing