Comparison of the Anticancer Effects of Pulsed Electric Field and He + O2 Plasma Jet

Cold atmospheric plasma (CAP) and pulsed electric field (PEF) technologies have received extensive attention for their potential beneficial effects in cancer therapy. As two emerging anticancer technologies, both CAP and PEF are related to high voltage electricity, so it is useful to compare their anticancer effects and underlying mechanism to further promote their clinical application. Here, based on three-dimensional (3D) multicellular tumor spheroids, the cytotoxicity of a He + O2 plasma jet or pulsed electric field on cancer cells was tested. It was found that the anticancer effects of the PEF mainly occurred within the first four hours of treatment, while the anticancer effects of the plasma jet were maintained for at least 24 h after irradiation. The PEF was shown to destroy the integrity of the cell membrane and selectively kill cancer cells in the S and G2/M phases, and the apoptosis was observed in the entire region of the 3D tumor spheroids. In contrast, the He + O2 plasma jet was shown to induce apoptosis by increasing cellular oxidative stress, and the apoptosis was observed only on the outermost layer of the 3D tumor spheroids.