Chemical mechanisms of non-thermal plasma action on cells

Non-thermal plasma (NTP) in the air around the cell layer or biological tissues is considered as a generator of reactive oxygen and nitrogen species, ions, and solvated/aquated electrons. This review covers current understanding on the effects of NTP in living systems, with the focus on the role of free radicals and other NTP-generated particles in the chemical modification of biomacromolecules and regulation of signal transduction. We summarise recent data on the impact of NTP-originated products on intracellular redox balance, mitochondrial biogenesis, cell membranes and organelles. In addition, we discuss the transport of NTP products across the biological membranes. Since the expression of numerous transporter systems differs at various stages of development, distinct cell lines, and in pathological conditions, experiments on NTP effects should be designed in various models for the assessment of cell- and tissue-specific response. Notably, NTP effects are observed throughout the whole tissue even when particles are generated at the surface. Special attention is paid to the NTP-treated solutions (phosphate buffered saline, Ringer’s solution, cell culture medium) as their composition and pH can be significantly altered. However, these data also suggest novel opportunities for the application of NTP and NTP-treated solutions in biomedicine. Studies on the mechanisms of NTP action on biological systems should contain analysis of events coupled to generation and accumulation of reactive oxygen and nitrogen species, neutral compounds, solvated electrons, and detection of new cellular targets of their action. This would allow developing of efficient and safe protocols for NTP applications in biology and medicine.