The activity of cold atmospheric plasma against high-grade glioma: a review

Cold atmospheric plasma (CAP), a partially ionized near-room temperature gas (argon or helium), generates a variety of oxygen and nitrogen reactive species which can have a multitude of downstream biological effects including cell death, inflammation, and immune modulation. CAP is therefore a powerful tool with many potential medical applications, particularly in cancer treatment. As primary treatment, CAP can be administered directly through a plasma jet, or indirectly via plasma activated substances (i.e. media, biogels, etc.). CAP has been shown to directly kill cancer cells by inducing RONS-mediated cell death mechanisms, enhance anti-tumor immunity or increase the tumor's responsiveness to systemic therapies. While the chemical factors (i.e. RONS-mediated apoptosis) is the most studied mechanism of CAP efficacy, CAP can also induce necrosis of cells through ultraviolet irradiation, thermal and electromagnetic effects, which tend to lead to necrosis. CAP has been shown to cause selective cell death in various cancers, including skin, breast, colorectal, head and neck, and more recently in gliomas, with minimal side effects to surrounding normal tissues.

We summarize the studies investigating CAP applications in neuro-oncology to date, including in vitro and pre-clinical studies, followed by a brief mention of ongoing clinical trials for CAP as a cancer treatment.