Session EF4: Plasma Medical & Agricultural Application IV

Cold Atmospheric Plasmas in Biology and Medicine: The Fundamentals

Cold atmospheric plasmas (CAP) sources have recently been playing an important role in various biomedical applications, which include the killing of pathogenic bacteria and viruses, the destruction of cancer cells and tumors, and the enhancement of wound healing via disinfection and proliferation of healthy cells¹. It has been shown that the biological effects of CAP are mostly mediated by the reactive oxygen and nitrogen species, ROS/RNS. These include O, OH, H₂O₂, O₃, O₂^-, O₂(¹Δ), NO, ONOO^-. The generation and transport of these reactive species proceed in several stages. Charged particles and other atomic and molecular reactive species are first produced in the main plasma ignition region. These species are then transported in the plasma afterglow, interact in a gas-liquid interface, until finally reaching their biological targets, such as cells and tissues. Both ROS and RNS possess strong oxidative properties and can trigger signaling pathways in biological cells. Therefore, delivering controllable doses of these species to cells and tissues can lead to specific biological outcomes including the onset of apoptosis, enhancement or suppression of cell proliferation, modified cell migration, etc. The ability to modulate cell behavior has crucial implications in various CAP biomedical applications such as wound healing and cancer treatment. In this paper the fundamental scientific basis of the application of CAP to cells and tissues is discussed and some applications in select healthcare therapies are presented.

¹ M. Laroussi, X. Lu, and M. Keidar, “Perspective: The Physics, Diagnostics, and Applications of Atmospheric Pressure Low Temperature Plasma Sources Used in Plasma Medicine”, J. Appl. Phys. 122, 020901 (2017).

    

Numerical modeling of how plasma interferes with cell fate

Cold atmospheric plasmas (CAPs) have been widely applied in the field of biomedicine, where specific CAP effects on cells and biomolecules via various pathways have been extensively investigated. A number of experimental works have suggested that the CAP-induced reactive oxygen/nitrogen species (RONS) affects cell fate (cell survival/death) [1]. Computational approach is useful to gain new insights into the fundamental mechanisms of CAP interactions with biomolecules. The author has developed a 0D intracellular biochemical reaction model quantifying the influence of RONS on the mitochondrial redox-mediated functions and energy metabolism [2]. For further understanding of how CAPs exert the biological effects, the present work examines the induction of cell death (apoptosis / necrosis) by CAP-induced stress. The model includes activation of death-receptors, mitochondrial signaling cascade pathways, initiator- and executor-caspases and regulators. The effects of CAP irradiation can be modeled as extrinsic or intrinsic stress. [1] K. Iuchi, et al, Arch. Biochem. Biophys. 654, 136 (2018). [2] T. Murakami, Scientific Reports, 9, 17138 (2019).   

Medical plasma gas improves corneal burn ulcers in rabbits

Gas plasma helps wounds heal in veterinary medicine, which is why gas medical plasma is used to study a wide range of animal models with different unsolved medical problems. The purpose of this study was to assess the experimental wound healing of corneal burns in rabbits exposed to corona plasma radiation. This investigation was conducted on 10 adult male white New Zealand rabbits of varying weights and ages. The Department of Animal Breeding and Laboratory of the Pasteur Institute of Iran prepared the rabbits, and the protocol for this study was conducted in compliance with the International Committees for the Protection of Laboratory Animal Rights-approved ethical norms. To induce anesthesia, intramuscular injections of 10% ketamine at 40 mg per kg body weight and 2% xylazine at 10 mg per kg body weight were given. After instilling 2 drops of 0.5% tetracaine into the right eye of each rabbit under general anesthesia, a 6 mm diameter circular filter paper containing 30 l of normal saline was put in the middle of the cornea for 60 seconds. After removing the filter paper, 2 mL of standard sterile saline was used to cleanse the eyes. They were separated into two groups of five. The second group received daily treatment for twenty days. At the end of 20 days, anesthesia was administered and ocular excision was performed on the animals. Pathological tests show that plasma corona radiation seems to help heal corneal burns in the group that was treated with it.   

Analysis of cell exposed to non-thermal atmospheric pressure plasma for effective gene transfer

Non-thermal atmospheric pressure plasma (NTAPP) has been used in biomedical researches [1]. One of its attractive applications is gene transfection for affecting cell fate. To reveal the mechanism of gene transfer using NTAPP, surface morphology of cells exposed to NTAPP was analyzed.

 

Murine fibroblast cells (L929) were exposed to NTAPP using a plasma jet source (He 2 slm; 9 kV; 12. 5 kHz) and fluorescent reagent (DiYO-1) was supplied to the cells. After 1 h incubation, the cells were observed by fluorescent microscopy.

 

NTAPP exposure more than 13 s introduced DiYO-1 into the cells. Then, glutaraldehyde was supplied to the cells for fixing their surface morphology. The cells were freeze-dried for scanning electron microscopy. For the cells exposed to NTAPP, pores were found on the cell membrane.

 

To exclude the possibility that the pores were formed during freeze-drying, the cells were observed in liquid medium using scanning ion microscopy (SICM) [2]. SICM revealed pores on the cell membrane. The pores formed by NTAPP exposure can play important roles in gene delivery.

 

[1] S. Kumagai et al., Jpn. J. Apple. Phys., 55, 01AF01 (2016) (OPEN ACCESS); https://doi.org/10.7567/JJAP.55.01AF01

[2] S. Watanabe et al., Rev. Sci. Instrum. 90, 123704 (2019); https://doi.org/10.1063/1.5118360   

Transdermal Administration of Adenosine and Eosin Y Using Microplasma

The strong barrier established by the human stratum corneum serves a protective purpose. It also prevents pharmacological compounds from being delivered into the skin. One of the most important functions of transdermal drug delivery is to get beyond the stratum corneum. We used microplasma discharge treatment to overcome this skin barrier. The permeation and retention of Adenosine through the skin of a Yucatan micropig’s skin were investigated using a Franz diffusion cell. HPLC was used to determine the amount of drug that had entered and remained inside the skin layer. We evaluated and compared Adenosine penetration through the treated and untreated skin by microplasma. After the treatment, the depth of penetration was measured using the Eosin Y dye. Microplasma treatment enhanced drug penetration through the epidermal layer of the skin, according to the findings in this study.