Continuous exposure to a uniform ELF-EMF reduces intracellular ROS levels in HeLa and IMR-90 cells.

<p>HeLa and IMR-90 cells were exposed to an EMF at 6 mT for 72 h and further subcultured under the same ELF-EMF for an additional 96 h. Indicated time denotes the total time cells were exposed to uniform ELF-EMFs. (A) Intracellular ROS levels were monitored by carboxy-H₂DCFDA fluorescence using flow cytometry. For each flow cytometric analysis, 10,000 cells were counted and plotted. The data are shown as overlapping histogram plots. (B) From data obtained in (A), the relative fluorescence intensity of EMF-exposed cells and untreated control was quantified from the geometric mean of fluorescence intensity in 10,000 cells and then plotted as the mean ± SD (n = 3). (C) Representative fluorescence microscopy images. Scale bar = 50 μm. Carboxy-H₂DCFDA (green) represents intracellular ROS levels. Cell nuclei are stained with Hoechst 33342 (blue). (D) Cells were incubated with 0.1 mU/mL GOx alone or GOx under a uniform EMF of 6 mT for 72 h. Cell viability was measured by MTT assays every 24 h and evaluated as a percentage relative to the viability of untreated cells (0 h). Data were plotted as the mean ± SD (n = 3). (E) After 72 h incubation of (D), intracellular ROS levels were monitored by carboxy-H₂DCFDA fluorescence through flow cytometry. For each flow cytometric analysis, 10,000 cells were counted and plotted (left) as the mean ± SD (n = 3). The data are shown as overlapping histogram plots (right). (B, D, E) P-values were determined by two-way ANOVA with the Bonferroni correction. Values of *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001 were considered statistically significant, and P > 0.05 was considered statistically not significant (ns).