Evaluation of a modified CD71 MicroFlow® method for the flow cytometric analysis of micronuclei in rat bone marrow erythrocytes

The aim of this study was to evaluate a modified flow cytometric method for the quantification of micronuclei in rat bone marrow reticulocytes. The method identified uses the erythrocyte pure fraction from cellulose filtered bone marrow with slight modifications to the widely published MicroFlow® method developed by Litron Laboratories, Rochester, NY for the detection of micronuclei in peripheral blood. A number of experiments were conducted to compare the micronucleus induction measured by flow cytometry with traditional microscopic analysis in male rats treated daily for 2 days with appropriate vehicle controls or various doses of cyclophosphamide (CP), mitomycin C (MMC), vinblastine sulfate (VBS), 1,2-dimethylhydrazine (DMH), etoposide (ETO), colchicine (COL), or 4-nitroquinoline-1-oxide (4NQO). In addition, for a subset of chemical we compared the induction of micronuclei in bone marrow and peripheral blood. The results from this study showed a very good correlation of micronucleus frequencies in bone marrow between microscopic analysis and the flow cytometry as well as between blood and bone marrow. In general, micronucleus frequencies of test compound treated animals and inter-animal variability were slightly lower by flow cytometric analysis compared to manual slide analysis. The data presented in this study support the use of the CD71 flow method for the analysis of micronuclei in rat bone marrow and also suggest that peripheral blood may be equally as sensitive as bone marrow in detecting a micronucleus response in short term studies.