Pin Electrode Reactor: A novel cold atmospheric plasma device and its potential in glioblastoma treatment

Abstract

Glioblastoma multiforme (GBM) is the most common and biologically aggressive brain tumour. The current standard therapy for GBM consists in surgical resection, followed by radiotherapy and chemotherapy. Yet, the treatment is limited due to the area for the surgical resection and for the inability of some drugs to cross the brain blood barrier, leading to a general prognostic of no more than a year. Cold atmospheric plasma (CAP) is a new approach in the treatment of this challenging disease. CAP interaction with cells is dependent on physical and chemical factors, with different plasma discharges, cell type, and culture conditions leading to different CAP activity. Considering the plasma self-adaptation that different plasma discharge modes can undergo, which leads to different interaction plasma/cells, the characterization of a new device is essential. In this study we analysed the effect of a novel large pin-to-plate non-thermal atmospheric plasma on U-251 MG cells under different conditions. The analysis of reactive oxygen and nitrogen species (RONS) on plasma, media and cells were also assessed. We were able to demonstrate that the pin-to-plate device is cytotoxic to GBM cells in a dose, time and ROS dependent manner. The measurements of RONS on plasma/media also give us an insight on the chemical effect of this novelty device, and the possibility to better understand the use of this device as a promising GBM therapy.

Plasma induced reactive oxygen species‐dependent cytotoxicity in glioblastoma 3D tumourspheres

“…For 2D cultures, significantly more cell death was evident 96 h after treatment compared with 24 h, with cytotoxicity found to be ROS-dependent. [29] Conversely, for both U-251 MG and A431 3D tumourspheres, the induced cytotoxicity after 24 h was proportional to the plasma dosage but was found to partially recover their RONS damage and regrow, similar to previous reports [14] and in contrast to cells grown in the 2D monolayer. [29] Our data also shows that the U-251 MG cell line is highly resistant to single-dose plasma treatments and is able to regrow quickly when compared to A431.…”

“…[29] Conversely, for both U-251 MG and A431 3D tumourspheres, the induced cytotoxicity after 24 h was proportional to the plasma dosage but was found to partially recover their RONS damage and regrow, similar to previous reports [14] and in contrast to cells grown in the 2D monolayer. [29] Our data also shows that the U-251 MG cell line is highly resistant to single-dose plasma treatments and is able to regrow quickly when compared to A431. These results have important implications for future animal model and human trials where single CAP treatments may be insufficient to yield significant benefits.…”

“…Therefore, the response of U‐251 MG tumourspheres to CAP is different from previous reports, and indeed to U‐251 MG cells grown in 2D cultures where we found, using the same plasma system where CAP treatment induced predominantly H 2 O 2 ‐dependent cytotoxicity. [ 29 ] Together, our data indicate a relative resistance of U‐251 MG tumourspheres to hydrogen peroxide during CAP‐induced cell death. Cell death may instead be mediated by other ROS species we have previously measured in the plasma plume or media, including OH, N 2 second positive system, N 2 + first negative system, nitrate, and ozone.…”

“…[27,28] We employed a U-251 MG 3D cell culture model, which enabled cell-cell and cell-ECM interactions in all three dimensions and mimicked diffusion-limited distribution of oxygen, nutrients, metabolites, and signaling molecules common in the microenvironment of in vivo tumors. Most of the research on the effects of CAP on cancer cells has been investigated by using 2D monolayer cell cultures [29,30] and a growing number of animal models. [11,13] There are also a few studies carried out using the pin to plate design [25,29] ; however, this is the first time that we are reporting the approach for induced cytotoxicity in 3D tumor spheroids.…”

“…Most of the research on the effects of CAP on cancer cells has been investigated by using 2D monolayer cell cultures [29,30] and a growing number of animal models. [11,13] There are also a few studies carried out using the pin to plate design [25,29] ; however, this is the first time that we are reporting the approach for induced cytotoxicity in 3D tumor spheroids.…”