Long-Range Noninvasive Electromagnetic Treatment of U87-MG Glioblastoma (in Vitro) by Plasma Discharge Tube With a Concave Reflective Electrode

Immersion of a 12.5-kHz helium plasma discharge tube (DT) inside a metallic reflective bowl-like electrode enhances the anisotropy and directs the electromagnetic emission outwards from DT. Fitting the emission amplitude spatial decay by exponential functions shows that with the reflective electrode, the emission spatially decreases 10 times slower than without the electrode. Such a way for directing the electromagnetic emission extends the effective spatial range of physical sensitization effect on UMG87 glioblastoma cancer cells from typical distance of several millimeters without the reflective electrode, up to several tens of millimeters with reflective electrode at floating or full DT central electrode potential. The decrease of UMG87 cell viability proportionally grows with the concentration of the intra-cellular Reactive Oxygen Species, and is detected not only at much larger axial distances (up to 10 cm), but also at non-zero radial distances from the DT center, reaching maximal effect in the vicinity of the walls of the reflective electrode. These findings look promising for the development of technology for distant non-ionizing and non-invasive electromagnetic treatment of deep-lying tumors.