Gas Plasma-Oxidized Liquids for Cancer Treatment: Preclinical Relevance, Immuno-Oncology, and Clinical Obstacles

Eric Freund,Sander Bekeschus

doi:10.1109/trpms.2020.3029982

Abstract

Gas plasmas, often referred to as cold physical plasma, are currently being investigated for their potential to serve as anticancer agents. Along similar lines, gas plasma-oxidized liquids as a carrier for reactive oxygen species have found their way into preclinical research. This review focuses on <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in vivo</i> studies that utilized such gas plasma-oxidized liquids for cancer therapies. These preclinical tumor models, treatment modalities, and types of liquids that were used are summarized and critically discussed. Among these studies, significant results were observed, indicating the potential of oxidative liquids to serve as an anticancer treatment. However, several steps have to be taken to enhance the quality and translational capacities of this approach in order to gain clinical acceptance for possible future cancer therapies. The most crucial steps include not only a careful selection of suitable liquids, with respect to their approval as medical products, but also the consideration of orthotopic and immunocompetent animal tumor models. This would increase the relevance of such studies and simultaneously allow studying the contribution of the most potent of all anticancer effectors, the immune system.

Highlights

I N THE last decade, many gas plasma sources were developed and designed for biomedical applications
This review focuses on the studies that were carried out to validate these effects in animal models and to recommend ways to increase the clinical relevance and acceptance of this promising approach
Repetitive treatments of the mice with 2.5 ml, up to ten times more volume than used in the other studies mentioned above, of gas plasma-oxidized or nonoxidized Ringer’s lactate were performed at days 2–4 and 8–11 before the animals were sacrificed at day 15

Summary

INTRODUCTION

I N THE last decade, many gas plasma sources were developed and designed for biomedical applications The latter include, for instance, the treatment of chronic and infected wounds, cosmetics, and oncology [1]–[9]. Because these ionized gases (gas plasmas) are being generated at physiological temperatures (

In Vivo EXPERIMENTS

MECHABISMS OF ACTION AND SELECTION OF SUITABLE LIQUIDS

IMMUNOGENICITY

FUTURE PERSPECTIVES

Findings

CONCLUSION