5 research outputs found

    Analysis of DNA Double-Strand Breaks and Cytotoxicity after 7 Tesla Magnetic Resonance Imaging of Isolated Human Lymphocytes

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    <div><p>The global use of magnetic resonance imaging (MRI) is constantly growing and the field strengths increasing. Yet, only little data about harmful biological effects caused by MRI exposure are available and published research analyzing the impact of MRI on DNA integrity reported controversial results. This in vitro study aimed to investigate the genotoxic and cytotoxic potential of 7 T ultra-high-field MRI on isolated human peripheral blood mononuclear cells. Hence, unstimulated mononuclear blood cells were exposed to 7 T static magnetic field alone or in combination with maximum permissible imaging gradients and radiofrequency pulses as well as to ionizing radiation during computed tomography and γ-ray exposure. DNA double-strand breaks were quantified by flow cytometry and automated microscopy analysis of immunofluorescence stained γH2AX. Cytotoxicity was studied by CellTiter-Blue viability assay and [<sup>3</sup>H]-thymidine proliferation assay. Exposure of unstimulated mononuclear blood cells to 7 T static magnetic field alone or combined with varying gradient magnetic fields and pulsed radiofrequency fields did not induce DNA double-strand breaks, whereas irradiation with X- and γ-rays led to a dose-dependent induction of γH2AX foci. The viability assay revealed a time- and dose-dependent decrease in metabolic activity only among samples exposed to γ-radiation. Further, there was no evidence for altered proliferation response after cells were exposed to 7 T MRI or low doses of ionizing radiation (≤ 0.2 Gy). These findings confirm the acceptance of MRI as a safe non-invasive diagnostic imaging tool, but whether MRI can induce other types of DNA lesions or DNA double-strand breaks during altered conditions still needs to be investigated.</p></div

    Analysis of γH2AX-stained DNA double-strand breaks by automated microscopy.

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    <p>γH2AX focus analysis was assessed in PBMCs immediately, 1 h and 20 h after indicated exposure conditions. (A) Representative images of DAPI (blue) and γH2AX-stained (green) PBMCs measured 1 h after indicated exposure. Bar: 5 μm. (B) Mean fluorescence intensity (MFI) of γH2AX-level, (C) amount of mean γH2AX foci/cell and (D) mean foci ratio from 16 independent experiments analyzed at three different time points after exposure as mean ± SEM (***: P ≤ 0.001; **: P ≤ 0.01; *: P ≤ 0.05; ns: P > 0.05). Cells with nuclei exhibiting the maximum γH2AX fluorescence signal throughout the whole nucleus were classified as pan-stained. These cells were recorded separately and not included into γH2AX focus and intensity analysis.</p

    Cell viability analysis of unstimulated PBMCs by CellTiter-Blue assay.

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    <p>Metabolic activity was measured 24 h, 48 h and 84 h after indicated exposure conditions. Diagrams display mean ± SEM of 16 independent experiments (***: P ≤ 0.001; **: P ≤ 0.01; ns: P > 0.05).</p