Elucidation of mechanism of apoptosis induced by cold atmospheric plasma toward to cancer therapy. Sensitization by physical and chemical modalities

In recent years, the development of cold atmospheric pressure plasma technology has been remarkable, and its use in many medical fields such as cancer treatment, hemostasis, and gene transfer is drawing attention. We attempted to induce cell death (apoptosis) by atmospheric pressure plasma and enhance it. The physical method of inducing cell death by using the combination of heat (hyperthermia) with plasma irradiation was described. Reactive oxygen species formed extracellularly are introduced into cells by enhancement of the permeability of the cell membrane. In addition, as a method for chemically inducing cell death, a method for reducing intracellular glutathione (GSH) with sulfasalazine, which is a cysteine transporter inhibitor, to increase sensitivity to reactive oxygen species was described. The effect of metal nanoparticles on atmospheric pressure plasma-induced apoptosis was described. Addition of platinum nanoparticles having catalase and superoxide dismutase (SOD) activities (having antioxidant activity) suppressed apoptosis by He plasma, but addition of gold nanoparticles (without antioxidant activity) enhanced apoptosis. (S.S.)