Cold atmospheric plasma in cancer therapy

TLDR

Cold atmospheric plasmas have been developed with ion temperatures near room temperature. The study reviews advances in cold plasma physics and its application to cancer therapy. The authors employed novel plasma diagnostics, conducted in‑vitro and in‑vivo studies, and identified reactive oxygen species–mediated apoptosis as a key mechanism of CAP on cancer cells. Measurements revealed streamer head charges of ~10⁸ electrons, fields of ~10⁷ V/m, and electron densities of ~10¹⁹ m⁻³, while CAP selectively killed cancer cells in vitro, reduced tumor size in vivo, and was more effective against cells in the S phase.

Abstract

Recent progress in atmospheric plasmas has led to the creation of cold plasmas with ion temperature close to room temperature. This paper outlines recent progress in understanding of cold plasma physics as well as application of cold atmospheric plasma (CAP) in cancer therapy. Varieties of novel plasma diagnostic techniques were developed recently in a quest to understand physics of CAP. It was established that the streamer head charge is about 108 electrons, the electrical field in the head vicinity is about 107 V/m, and the electron density of the streamer column is about 1019 m−3. Both in-vitro and in-vivo studies of CAP action on cancer were performed. It was shown that the cold plasma application selectively eradicates cancer cells in-vitro without damaging normal cells and significantly reduces tumor size in-vivo. Studies indicate that the mechanism of action of cold plasma on cancer cells is related to generation of reactive oxygen species with possible induction of the apoptosis pathway. It is also shown that the cancer cells are more susceptible to the effects of CAP because a greater percentage of cells are in the S phase of the cell cycle.