Role of Short- and Long-Lived Reactive Species on the Selectivity and Anti-Cancer Action of Plasma Treatment In Vitro

(1) Plasma-activated liquids (PAL) have been extensively studied for their anti-cancer properties. Two treatment modalities can be applied to the cells, direct and indirect plasma treatments, which differ by the environment to which the cells are exposed. For direct plasma treatment, the cells cover...

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Main Authors: Kyriakos Sklias, João Santos Sousa, Pierre-Marie Girard
Format: Article
Language:English
Published: MDPI AG 2021-02-01
Series:Cancers
Subjects:
Online Access:https://www.mdpi.com/2072-6694/13/4/615
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author Kyriakos Sklias
João Santos Sousa
Pierre-Marie Girard
author_facet Kyriakos Sklias
João Santos Sousa
Pierre-Marie Girard
author_sort Kyriakos Sklias
collection DOAJ
description (1) Plasma-activated liquids (PAL) have been extensively studied for their anti-cancer properties. Two treatment modalities can be applied to the cells, direct and indirect plasma treatments, which differ by the environment to which the cells are exposed. For direct plasma treatment, the cells covered by a liquid are present during the plasma treatment time (phase I, plasma ON) and the incubation time (phase II, plasma OFF), while for indirect plasma treatment, phase I is cell-free and cells are only exposed to PAL during phase II. The scope of this work was to study these two treatment modalities to bring new insights into the potential use of PAL for cancer treatment. (2) We used two models of head and neck cancer cells, CAL27 and FaDu, and three models of normal cells (1Br3, NHK, and RPE-hTERT). PBS was used as the liquid of interest, and the concentration of plasma-induced H<sub>2</sub>O<sub>2</sub>, NO<sub>2</sub><sup>−</sup> and NO<sub>3</sub><sup>−</sup>, as well as pH change, were measured. Cells were exposed to direct plasma treatment, indirect plasma treatment or reconstituted buffer (PBS adjusted with plasma-induced concentrations of H<sub>2</sub>O<sub>2</sub>, NO<sub>2</sub><sup>−</sup>, NO<sub>3</sub><sup>−</sup> and pH). Metabolic cell activity, cell viability, lipid peroxidation, intracellular ROS production and caspase 3/7 induction were quantified. (3) If we showed that direct plasma treatment is slightly more efficient than indirect plasma treatment and reconstituted buffer at inducing lipid peroxidation, intracellular increase of ROS and cancer cell death in tumor cells, our data also revealed that reconstituted buffer is equivalent to indirect plasma treatment. In contrast, normal cells are quite insensitive to these two last treatment modalities. However, they are extremely sensitive to direct plasma treatment. Indeed, we found that phase I and phase II act in synergy to trigger cell death in normal cells and are additive concerning tumor cell death. Our data also highlight the presence in plasma-treated PBS of yet unidentified short-lived reactive species that contribute to cell death. (4) In this study, we provide strong evidence that, in vitro, the concentration of RONS (H<sub>2</sub>O<sub>2</sub>, NO<sub>2</sub><sup>−</sup> and NO<sub>3</sub><sup>−</sup>) in combination with the acidic pH are the main drivers of plasma-induced PBS toxicity in tumor cells but not in normal cells, which makes ad hoc reconstituted solutions powerful anti-tumor treatments. In marked contrast, direct plasma treatment is deleterious for normal cells in vitro and should be avoided. Based on our results, we discuss the limitations to the use of PAL for cancer treatments.
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spelling doaj.art-3ea7a558ca6d40308a3bd1d6539607b82023-12-03T12:21:15ZengMDPI AGCancers2072-66942021-02-0113461510.3390/cancers13040615Role of Short- and Long-Lived Reactive Species on the Selectivity and Anti-Cancer Action of Plasma Treatment In VitroKyriakos Sklias0João Santos Sousa1Pierre-Marie Girard2Université Paris-Saclay, CNRS, Laboratoire de Physique des Gaz et des Plasmas, 91405 Orsay, FranceUniversité Paris-Saclay, CNRS, Laboratoire de Physique des Gaz et des Plasmas, 91405 Orsay, FranceInstitut Curie, PSL Research University, CNRS, INSERM, UMR 3347, 91405 Orsay, France(1) Plasma-activated liquids (PAL) have been extensively studied for their anti-cancer properties. Two treatment modalities can be applied to the cells, direct and indirect plasma treatments, which differ by the environment to which the cells are exposed. For direct plasma treatment, the cells covered by a liquid are present during the plasma treatment time (phase I, plasma ON) and the incubation time (phase II, plasma OFF), while for indirect plasma treatment, phase I is cell-free and cells are only exposed to PAL during phase II. The scope of this work was to study these two treatment modalities to bring new insights into the potential use of PAL for cancer treatment. (2) We used two models of head and neck cancer cells, CAL27 and FaDu, and three models of normal cells (1Br3, NHK, and RPE-hTERT). PBS was used as the liquid of interest, and the concentration of plasma-induced H<sub>2</sub>O<sub>2</sub>, NO<sub>2</sub><sup>−</sup> and NO<sub>3</sub><sup>−</sup>, as well as pH change, were measured. Cells were exposed to direct plasma treatment, indirect plasma treatment or reconstituted buffer (PBS adjusted with plasma-induced concentrations of H<sub>2</sub>O<sub>2</sub>, NO<sub>2</sub><sup>−</sup>, NO<sub>3</sub><sup>−</sup> and pH). Metabolic cell activity, cell viability, lipid peroxidation, intracellular ROS production and caspase 3/7 induction were quantified. (3) If we showed that direct plasma treatment is slightly more efficient than indirect plasma treatment and reconstituted buffer at inducing lipid peroxidation, intracellular increase of ROS and cancer cell death in tumor cells, our data also revealed that reconstituted buffer is equivalent to indirect plasma treatment. In contrast, normal cells are quite insensitive to these two last treatment modalities. However, they are extremely sensitive to direct plasma treatment. Indeed, we found that phase I and phase II act in synergy to trigger cell death in normal cells and are additive concerning tumor cell death. Our data also highlight the presence in plasma-treated PBS of yet unidentified short-lived reactive species that contribute to cell death. (4) In this study, we provide strong evidence that, in vitro, the concentration of RONS (H<sub>2</sub>O<sub>2</sub>, NO<sub>2</sub><sup>−</sup> and NO<sub>3</sub><sup>−</sup>) in combination with the acidic pH are the main drivers of plasma-induced PBS toxicity in tumor cells but not in normal cells, which makes ad hoc reconstituted solutions powerful anti-tumor treatments. In marked contrast, direct plasma treatment is deleterious for normal cells in vitro and should be avoided. Based on our results, we discuss the limitations to the use of PAL for cancer treatments.https://www.mdpi.com/2072-6694/13/4/615cold atmospheric-pressure plasmaplasma activated liquidplasma cancer treatmentplasma medicinedirect treatmentindirect treatment
spellingShingle Kyriakos Sklias
João Santos Sousa
Pierre-Marie Girard
Role of Short- and Long-Lived Reactive Species on the Selectivity and Anti-Cancer Action of Plasma Treatment In Vitro
Cancers
cold atmospheric-pressure plasma
plasma activated liquid
plasma cancer treatment
plasma medicine
direct treatment
indirect treatment
title Role of Short- and Long-Lived Reactive Species on the Selectivity and Anti-Cancer Action of Plasma Treatment In Vitro
title_full Role of Short- and Long-Lived Reactive Species on the Selectivity and Anti-Cancer Action of Plasma Treatment In Vitro
title_fullStr Role of Short- and Long-Lived Reactive Species on the Selectivity and Anti-Cancer Action of Plasma Treatment In Vitro
title_full_unstemmed Role of Short- and Long-Lived Reactive Species on the Selectivity and Anti-Cancer Action of Plasma Treatment In Vitro
title_short Role of Short- and Long-Lived Reactive Species on the Selectivity and Anti-Cancer Action of Plasma Treatment In Vitro
title_sort role of short and long lived reactive species on the selectivity and anti cancer action of plasma treatment in vitro
topic cold atmospheric-pressure plasma
plasma activated liquid
plasma cancer treatment
plasma medicine
direct treatment
indirect treatment
url https://www.mdpi.com/2072-6694/13/4/615
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AT joaosantossousa roleofshortandlonglivedreactivespeciesontheselectivityandanticanceractionofplasmatreatmentinvitro
AT pierremariegirard roleofshortandlonglivedreactivespeciesontheselectivityandanticanceractionofplasmatreatmentinvitro