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Author: Weltmann, Klaus-Dieter × Author: von Woedtke, Thomas × DDC: 610 × Type: article ×

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    Elevated H2AX Phosphorylation Observed with kINPen Plasma Treatment Is Not Caused by ROS-Mediated DNA Damage but Is the Consequence of Apoptosis
    (London: Hindawi, 2019) Bekeschus, Sander; Schütz, Clarissa S.; Nießner, Felix; Wende, Kristian; Weltmann, Klaus-Dieter; Gelbrich, Nadine; von Woedtke, Thomas; Schmidt, Anke; Stope, Matthias B.
    Phosphorylated histone 2AX (γH2AX) is a long-standing marker for DNA double-strand breaks (DSBs) from ionizing radiation in the field of radiobiology. This led to the perception of γH2AX being a general marker of direct DNA damage with the treatment of other agents such as low-dose exogenous ROS that unlikely act on cellular DNA directly. Cold physical plasma confers biomedical effects majorly via release of reactive oxygen and nitrogen species (ROS). In vitro, increase of γH2AX has often been observed with plasma treatment, leading to the conclusion that DNA damage is a direct consequence of plasma exposure. However, increase in γH2AX also occurs during apoptosis, which is often observed with plasma treatment as well. Moreover, it must be questioned if plasma-derived ROS can reach into the nucleus and still be reactive enough to damage DNA directly. We investigated γH2AX induction in a lymphocyte cell line upon ROS exposure (plasma, hydrogen peroxide, or hypochlorous acid) or UV-B light. Cytotoxicity and γH2AX induction was abrogated by the use of antioxidants with all types of ROS treatment but not UV radiation. H2AX phosphorylation levels were overall independent of analyzing either all nucleated cells or segmenting γH2AX phosphorylation for each cell cycle phase. SB202190 (p38-MAPK inhibitor) and Z-VAD-FMK (pan-caspase inhibitor) significantly inhibited γH2AX induction upon ROS but not UV treatment. Finally, and despite γH2AX induction, UV but not plasma treatment led to significantly increased micronucleus formation, which is a functional read-out of genotoxic DNA DSBs. We conclude that plasma-mediated and low-ROS γH2AX induction depends on caspase activation and hence is not the cause but consequence of apoptosis induction. Moreover, we could not identify lasting mutagenic effects with plasma treatment despite phosphorylation of H2AX.
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    Effects of cold atmospheric pressure plasma and disinfecting agents on Candida albicans in root canals of extracted human teeth
    (Weinheim : Wiley-VCH-Verl., 2020) Kerlikowski, Anne; Matthes, Rutger; Pink, Christiane; Steffen, Heike; Schlüter, Rabea; Holtfreter, Birte; Weltmann, Klaus-Dieter; von Woedtke, Thomas; Kocher, Thomas; Jablonowski, Lukasz
    Reinfection in endodontically treated teeth is linked to the complexity of the root canal system, which is problematic to reach with conventional disinfection methods. As plasma is expected to have the ability to sanitize narrow areas, the aim of this study was to analyze the effect of cold atmospheric pressure plasma (CAP) on Candida albicans in root canals of extracted human teeth. CAP was applied as mono treatment and in combination with standard endodontic disinfectants (sodium hypochlorite, chlorhexidine and octenidine). Disinfection efficiency was evaluated as reduction of the logarithm of colony forming units per milliliter (log10 CFU/mL) supported by scanning electron microscopy as imaging technique. Plasma alone showed the highest reduction of log10 CFU, suggesting the best disinfection properties of all tested agents. © 2020 The Authors. Journal of Biophotonics published by Wiley-VCH GmbH.
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    Cell stimulation versus cell death induced by sequential treatments with pulsed electric fields and cold atmospheric pressure plasma
    (San Francisco, California, US : PLOS, 2018) Steuer, Anna; Wolff, Christina M.; von Woedtke, Thomas; Weltmann, Klaus-Dieter; Kolb, Juergen F.
    Pulsed electric fields (PEFs) and cold atmospheric pressure plasma (CAP) are currently both investigated for medical applications. The exposure of cells to PEFs can induce the formation of pores in cell membranes and consequently facilitate the uptake of molecules. In contrast, CAP mainly acts through reactive species that are generated in the liquid environment. The objective of this study was to determine, if PEFs combined with plasma-treated cell culture medium can mutually reinforce effects on viability of mammalian cells. Experiments were conducted with rat liver epithelial WB-F344 cells and their tumorigenic counterpart WB-ras for a direct comparison of non-tumorigenic and tumorigenic cells from the same origin. Viability after treatments strongly depended on cell type and applied field strength. Notably, tumorigenic WB-ras cells responded more sensitive to the respective treatments than non-tumorigenic WB-F344 cells. More cells were killed when plasma-treated medium was applied first in combination with treatments with 100-μs PEFs. For the reversed treatment order, i.e. application of PEFs first, the combination with 100-ns PEFs resulted in a stimulating effect for non-tumorigenic but not for tumorigenic cells. The results suggest that other mechanisms, besides simple pore formation, contributed to the mutually reinforcing effects of the two methods.