IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 38, NO. 8, AUGUST 2010 1949 Tumoral and Normal Cells Treatment With High-Voltage Pulsed Cold Atmospheric Plasma Jets Nicolae Georgescu and Andreea Roxana Lupu Abstract—High-voltage pulsed cold atmospheric plasma jets were used to treat tumoral (B16 and COLO320) and normal (macrophage) cells. Cold atmospheric plasma jet generator and plasma jet physical characteristics are presented. The treatment of the tumoral cells intended to obtain their apoptosis. For tumoral cells, percents of up to 70% apoptosis have been obtained, using helium plasma, activated with up to 2% oxygen. In the same exper- imental conditions, the plasma treatment did not induce apoptosis in normal (macrophage) cells. In addition, the macrophage cells were not activated by the plasma jets. Index Terms—Cells apoptosis, cold atmospheric plasma jets, pulsed high voltage. I. I NTRODUCTION C OLD ATMOSPHERIC plasma jets are studied as a new treatment method in the biomedical field [1]–[8]. This treatment has a strong chemical action, without the gaseous residues or dangerous radiations disadvantage and this ap- pliance should have the advantage of a “targeted treatment,” avoiding nonignorable side effects that inevitably also act on healthy cells too, by affecting their functionality. Thanks to relatively small costs and easy usability, the plasma device could be included in every hospital endowment for oncology, dermatology departments, etc. The cold plasma jets act at the cellular level to remove diseased tissue without inflammation and damage. In cancer therapy, based on destruction of tumor cells by use of different methods, one should remember that there are two types of cellular death: apoptosis and necrosis. Apoptosis, the process of programmed cell death, involves a series of morphological processes leading to controlled cellular self-destruction. The second death cell type, necrosis, represents a form of traumatic cell death that results from acute cellular injury. Apoptosis, in contrast to necrosis, is not harmful to the host and does not induce any inflammatory reaction. This fact is very important because it is known that chronic inflammation promote tumori- genesis [9]. In order to assess the usage of the atmospheric pressure plasma jet as an effective device in tumor treatment, we studied the onset of the apoptosis. Our aim was to maximize this controlled cell death. Manuscript received October 31, 2009; revised January 5, 2009; accepted January 11, 2010. Date of publication February 17, 2010; date of current version August 11, 2010. This work was supported by the Romanian Ministry of Education and Research under Project IDEI_54/2007. The authors are with the National Institute for Laser, Plasma and Radiation Physics, 76900 Bucharest, Romania (e-mail: ngeorge@infim.ro; ldreea@yahoo.com). Digital Object Identifier 10.1109/TPS.2010.2041075 At atmospheric pressure, the plasma jets are produced by electric discharges in helium or argon. However, pure helium or argon plasma jets have a low chemical activity, thus being inappropriate for biomedical applications. Their chemical acti- vation is necessary, this implying that some chemically active species such as: oxygen atoms, OH radicals, nitrogen atoms, NO radicals, nitrogen ions, helium/argon excited atoms, etc. exist in the plasma jet. The most important chemically active species are oxygen atoms and OH radicals. That is why the introduction of the oxygen in the discharge area is of greatest importance to chemical activation. When obtaining chemically active species, the electrons produced in electric discharges have the essential contribution. The collisions between fast electrons and atoms and molecules result in enhanced levels of excitation, dissociation, and ionization, i.e., enhanced plasma chemistry. Introducing the oxygen in the discharge area implies finding a solution to the following problem: The concentration of the oxygen must be sufficiently low in order not to exces- sively disturb the electric discharge, but sufficiently high for a strong chemical activation of the plasma jet. That is why a very important result of our experiments was to determine optimal oxygen concentrations in view of applications in the biomedical field. A major cause of antitumor chemotherapy failure is the development of multidrug resistance (MDR) of tumors due to MDR efflux pumps which extrude anticancer drugs from the tumor cells [10]. This paper reveals the effect of high- voltage pulsed repetitive cold atmospheric plasma jets which are chemically activated with oxygen, on B16 tumoral cells (murine melanoma cell line) and COLO320 multidrug resistant cells (human colon cancer cell line). In order to emphasize the plasma effect, we have used Verapamil as well-known MDR efflux pumps inhibitor. A comparative study between the treatment of the tumoral and a type of normal cells is presented. Our experiments and results allow the release of an animal (murine) model for in vivo study of melanonma. II. EXPERIMENTAL SETUP A. Cold Atmospheric Plasma Jet Generator The cold atmospheric plasma jet generator, shown in Fig. 1, replaced our old devices, made using medical syringes [11]. This new generator is similar with the device shown in [4], which works with ac voltages. In our case, pulsed high voltages are used. The advantage of the new structure is that it allows for flexibility during the modification of various geometrical parameters. 0093-3813/$26.00 © 2010 IEEE