E. coli OMVs produce morphopathogenic changes to Caco-2 cells consistent with endoreplication and can induce aneuploidy. (A) Immunofluorescence labelling of actin (red), cytokeratin 18 (green), and nuclei blue was used to show that OMVs cause endoreplication in Caco-2 cells over time. Images are from a single representative experiment. Original magnification = 20×, NA 0.50 objective used, scale bar indicates 50 μm. (B) OMVs (5 μg/ml) are associated with the generation of aneuploidy in Caco-2 cells exposed for 7 days to DH5α and O157:H7 OMVs, as measured using flow cytometry of propidium iodide stained and RNase 1 treated cells. *, results are significantly different from untreated controls (p ≤ 0.05). ANOVA, followed by two-sided Dunnet’s post hoc test. Results are ± SEM of three independent experiments.