Electromagnetic Nature of Distant Interaction of the Atmospheric Pressure Helium Plasma Discharge Tube with Glioblastoma Cancer Cells

Abstract

Atmospheric pressure coaxial gaseous discharge tubes (DTs) with helium have demonstrated potential for in vitro inactivation or sensitization of glioblastoma cancer cells. Here, we study the effect of two configurations of the DT electrode system on its electromagnetic emissivity as well as other physical factors (heating and UV emission) that form in the vicinity of this device. We demonstrate that the configuration of the DT electrodes that concentrates the discharge streamers near the top of the device has a distant (cm scale) deactivation effect on U87-MG glioblastoma cancer cells when irradiated, without measurable UV components in the DT optical emission spectra. This effect persists even through different barriers such as glass, plastic, or quartz Petri dishes but is eliminated when glass or plastic dishes are filled with water. These findings demonstrate the potential for development of noninvasive, physical-based treatment methods of deep-tissue tumors.

Multi-time-frame cell physiology assessment of cold atmospheric plasma emission bioeffects

“…Recent studies have demonstrated that CAP generated in a confined, dielectric vessel, further referred to as a discharge tube (DT), can also reduce cell viability and sensitize U87-MG cells to the primary glioblastoma chemotherapeutic temozolomide (TMZ) [10]. The spatial distribution of DT generated electric fields and thermal effects have recently been determined, demonstrating the ability to non-invasively treat cells at a distance of 1-2 cm [11]. The addition of a cooling fan system to the DT also eliminates the thermal effects, allowing for bioeffects study without the impact of thermal effects [11].…”

“…The spatial distribution of DT generated electric fields and thermal effects have recently been determined, demonstrating the ability to non-invasively treat cells at a distance of 1-2 cm [11]. The addition of a cooling fan system to the DT also eliminates the thermal effects, allowing for bioeffects study without the impact of thermal effects [11]. With this in mind, the present study investigates the bioeffects of DT treatment on U87-MG glioblastoma multiform cancer cells considering separation distance between DT and cell samples, treatment duration, multiple treatments, incubation time post treatment, and screening of EM frequency bands by solid and liquid barriers.…”

“…In a previous study, we characterized the electromagnetic field size and amplitude generated by the discharge tube (DT), its thermal heating area and degree, and development of a cooling systems to minimize thermal bioeffects [11]. To better understand the DT bioeffects on cells at a distance we varied the separation distance from 0 to 16 cm in the Z direction (above the DT) for continuous treatment durations of 4, 8, and 12 minutes (Figure 3).…”

“…To better understand the DT bioeffects on cells at a distance we varied the separation distance from 0 to 16 cm in the Z direction (above the DT) for continuous treatment durations of 4, 8, and 12 minutes (Figure 3). All experiments shown herein were conducted with a directed fan to cool the discharge tube and eliminate thermal effects as demonstrated in [11]. 24 hours following a single 4-minute DT treatment, changes in cell viability were only observed at Z = 0 cm when the cell dish was in direct contact with the DT.…”

“…At Z = 0 cm, cell dish heating was observed and could not be eliminated using a cooling fan. Thermal effects were eliminated at separation distances of 1 and 2 cm by use of a cooling fan to cool the DT [11]. 24 hours following a single 8-minute DT treatment, cell viability was reduced at Z = 1 cm, with 7% of cells moving into early apoptosis and 3% of cells displaying signs of necrosis.…”