OECD GUIDELINE FOR ThE TESTING OF ChEMICaLS Proposal for updating Test Guideline 487 In Vitro Mammalian Cell Micronucleus Test

Introduction:
This document outlines the proposal for updating Test Guideline 487, In Vitro Mammalian Cell Micronucleus Test, by the Organization for Economic Cooperation and Development (OECD). The update aims to include information on the use of protocols with and without the actin polymerization inhibitor cytochalasin B, as well as the potential for identifying clastogenic and aneugenic chemicals using immunochemical labelling and fluorescence in situ hybridization. The guideline also discusses the importance of considering cell type, p53 status, genetic stability, DNa repair capacity, and origin when selecting cells for testing.

Key Points:

* The In Vitro Mammalian Cell Micronucleus Test (MNvit) is a robust and effective method for detecting clastogenic and aneugenic chemicals.
* The OECD proposes an update to Test Guideline 487 to include information on protocols with and without cytochalasin B, as well as the use of immunochemical labelling and fluorescence in situ hybridization for identifying clastogenic and aneugenic events.
* The selection of cell types for testing is critical, and the guideline emphasizes the importance of considering p53 status, genetic stability, DNa repair capacity, and origin.
* Exogenous sources of metabolic activation should be used for cells with inadequate endogenous metabolic capacity, and care should be taken to avoid artifactual positive results.
* Mitosis must occur in both treated and untreated cultures, and micronuclei should be scored in interphase cells that have completed mitosis.
* Positive controls should be used to demonstrate the metabolic capability of the metabolic activation system and the responsiveness of the test system.
* a variety of cell lines and types can be used for testing, including human peripheral blood lymphocytes, ChO, V79, ChL/IU, L5178Y, and hepaRG cells.

Main Message:
The proposed update to Test Guideline 487 provides comprehensive guidance on the use of the In Vitro Mammalian Cell Micronucleus Test for detecting clastogenic and aneugenic chemicals. The guideline emphasizes the importance of selecting appropriate cell types and using positive controls to ensure the validity of the test. The inclusion of information on protocols with and without cytochalasin B and the potential for identifying clastogenic and aneugenic events using immunochemical labelling and fluorescence in situ hybridization further strengthens the utility of this test method. By following the guidelines outlined in this update, regulatory agencies and testing laboratories can ensure the accuracy and reliability of test results for assessing the genotoxic potential of chemicals.

“OECD GUIDELINE FOR ThE TESTING OF ChEMICaLS Proposal for Updating Test Guideline 487 In Vitro Mammalian Cell Micronucleus Test.” OECD, 2010.