title: Bystander Effect Induced by Electroporation is Possibly Mediated by Microvesicles and Dependent on Pulse Amplitude, Repetition Frequency and Cell Type.
abstract: Bystander effect, a known phenomenon in radiation biology, where irradiated cells release signals which cause damage to nearby, unirradiated cells, has not been explored in electroporated cells yet. Therefore, our aim was to determine whether bystander effect is present in electroporated melanoma cells in vitro, by determining viability of non-electroporated cells exposed to medium from electroporated cells and by the release of microvesicles as potential indicators of the bystander effect. Here, we demonstrated that electroporation of cells induces bystander effect: Cells exposed to electric pulses mediated their damage to the non-electroporated cells, thus decreasing cell viability. We have shown that shedding microvesicles may be one of the ways used by the cells to mediate the death signals to the neighboring cells. The murine melanoma B16F1 cell line was found to be more electrosensitive and thus more prone to bystander effect than the canine melanoma CMeC-1 cell line. In B16F1 cell line, bystander effect was present above the level of electropermeabilization of the cells, with the threshold at 800 V/cm. Furthermore, with increasing electric field intensities and the number of pulses, the bystander effect also increased. In conclusion, electroporation can induce bystander effect which may be mediated by microvesicles, and depends on pulse amplitude, repetition frequency and cell type.
authors.affiliation: Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska ulica 2, 1000, Ljubljana, Slovenia.
authors.forename: Ajda
authors.initials: A
authors.lastname: Prevc
authors.affiliation: National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia.
authors.forename: Apolonija
authors.initials: A
authors.lastname: Bedina Zavec
authors.affiliation: Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska ulica 2, 1000, Ljubljana, Slovenia.|Faculty of Health Sciences, University of Primorska, Polje 42, 6310, Izola, Slovenia.
authors.forename: Maja
authors.initials: M
authors.lastname: Cemazar
authors.affiliation: Department of Cytopathology, Institute of Oncology Ljubljana, Zaloska 2, 1000, Ljubljana, Slovenia.
authors.forename: Veronika
authors.initials: V
authors.lastname: Kloboves-Prevodnik
authors.affiliation: Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska ulica 2, 1000, Ljubljana, Slovenia.
authors.forename: Monika
authors.initials: M
authors.lastname: Stimac
authors.affiliation: Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska ulica 2, 1000, Ljubljana, Slovenia.
authors.forename: Vesna
authors.initials: V
authors.lastname: Todorovic
authors.affiliation: Department of Radiation Oncology, Institute of Oncology Ljubljana, Zaloska 2, 1000, Ljubljana, Slovenia.
authors.forename: Primoz
authors.initials: P
authors.lastname: Strojan
authors.affiliation: Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska ulica 2, 1000, Ljubljana, Slovenia. gsersa@onko-i.si.
authors.forename: Gregor
authors.initials: G
authors.lastname: Sersa
mesh_terms: D000818:Animals; D024201:Bystander Effect; D045744:Cell Line, Tumor; D002463:Cell Membrane Permeability / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D055252:Cell-Derived Microparticles / Q000378:metabolism; D004285:Dogs; D018274:Electroporation / Q000379:methods; D008546:Melanoma, Experimental; D051379:Mice; D011839:Radiation, Ionizing
keywords: Bystander effect; Electroporation; Ionizing radiation; Medium transfer method; Melanoma cell lines; Microvesicles