Low-temperature plasmas at atmospheric pressure: toward new pharmaceutical treatments in medicine

Plasma Applications in Biomedicine: A Groundbreaking Intersection between Physics and Life Sciences

Plasma applications in biomedicine represent a groundbreaking intersection between physics and life sciences, unveiling novel approaches to disease treatment and tissue regeneration [...].

Comparative assessment of direct and indirect cold atmospheric plasma effects, based on helium and argon, on human glioblastoma: an in vitro and in vivo study

Recent research has highlighted the promising potential of cold atmospheric plasma (CAP) in cancer therapy. However, variations in study outcomes are attributed to differences in CAP devices and plasma parameters, which lead to diverse compositions of plasma products, including electrons, charged particles, reactive species, UV light, and heat. This study aimed to evaluate and compare the optimal exposure time, duration, and direction-dependent cellular effects of two CAPs, based on argon and helium gases, on glioblastoma U-87 MG cancer cells and an animal model of GBM. Two plasma jets were used as low-temperature plasma sources in which helium or argon gas was ionized by high voltage (4.5 kV) and frequency (20 kHz). In vitro assessments on human GBM and normal astrocyte cell lines, using MTT assays, flow cytometry analysis, wound healing assays, and immunocytochemistry for Caspase3 and P53 proteins, demonstrated that all studied plasma jets, especially indirect argon CAP, selectively induced apoptosis, hindered tumor cell growth, and inhibited migration. These effects occurred concurrently with increased intracellular levels of reactive oxygen species and decreased total antioxidant capacity in the cells. In vivo results further supported these findings, indicating that single indirect argon and direct helium CAP therapy, equal to high dose Temozolomide treatment, induced tumor cell death in a rat model of GBM. This was concurrent with a reduction in tumor size observed through PET-CT scan imaging and a significant increase in the survival rate. Additionally, there was a decrease in GFAP protein levels, a significant GBM tumor marker, and an increase in P53 protein expression based on immunohistochemical analyses. Furthermore, Ledge beam test analysis revealed general motor function improvement after indirect argon CAP therapy, similar to Temozolomide treatment. Taken together, these results suggest that CAP therapy, using indirect argon and direct helium jets, holds great promise for clinical applications in GBM treatment.

Cold atmospheric plasma (CAP) treatment increased reactive oxygen and nitrogen species (RONS) levels in tumor samples obtained from patients with low-grade glioma

Low-grade gliomas (LGGs) are a heterogeneous group of tumors with an average 10-year survival rate of 40%-55%. Current treatment options include chemotherapy, radiotherapy, and gross total resection (GTR) of the tumor. The extent of resection (EOR) plays an important role in improving surgical outcomes. However, the major obstacle in treating low-grade gliomas is their diffused nature and the presence of residual cancer cells at the tumor margins post resection. Cold Atmospheric Plasma (CAP) has shown to be effective in targeted killing of tumor cells in various glioma cell lines without affecting non-tumor cells through Reactive Oxygen and Nitrogen Species (RONS). However, no study on the effectiveness of CAP has been carried out in LGG tissues till date. In this study, we applied helium-based CAP on tumor tissues resected from LGG patients. Our results show that CAP is effective in promoting RONS accumulation in LGG tissues when CAP jet parameters are set at 4 kV voltage, 5 min treatment time and 3 lpm gas flow rate. We also observed that CAP jet is more effective in thinner slice preparations of tumor as compared to thick tumor samples. Our results indicate that CAP could prove to be an effective adjunct therapy in glioma surgery to target residual cancer cells to improve surgical outcome of patients with low-grade glioma.

Rotational Transitions in the N2 + Ion Induced by Collisions with Helium Atoms in Cold Helium Plasmas. A Quasiclassical Trajectory Study

Cross-sections of state-to-state rotational transitions in electronically ground-state 14N 2 + ${{\rm{N}}_2^ + }$ (X2Σ g + ${{\Sigma }_{g}^{+}}$ ) ions induced by collisions with 4 He atoms have been calculated using a quasiclassical trajectory method and a set of artificial neural networks representing theN 2 + ${{\rm{N}}_2^ + }$ /He potential energy surface. The training points for the neural networks have been calculated at a MCSCF (multi-configuration self-consistent field)/aug-cc-pVQZ level. A broad range of theN 2 + ${{\rm{N}}_2^ + }$ /He collision energy has been considered (E c o l l ≤ 100 ${{E}_{{\rm c}{\rm o}{\rm l}{\rm l}}\le 100}$  eV) and the efficiency of vibrational transitions in theN 2 + ${{\rm{N}}_2^ + }$ ion has also been analyzed. It has been found that vibrational transitions are negligible with respect to rotational transitions up toE c o l l ≈ 10 ${{E}_{{\rm c}{\rm o}{\rm l}{\rm l}}\approx 10}$  eV and that above this energy, both rotational and vibrational transitions inN 2 + ${{\rm{N}}_2^ + }$ are marginal in theN 2 + ${{\rm{N}}_2^ + }$ /He collisions.

Transcriptomic and physiological analyses reveal changes in secondary metabolite and endogenous hormone in ginger (Zingiber officinale Rosc.) in response to postharvest chilling stress

Storing postharvest ginger at low temperatures can extend its shelf life, but can also lead to chilling injury, loss of flavor, and excessive water loss. To investigate the effects of chilling stress on ginger quality, morphological, physiological, and transcriptomic changes were examined after storage at 26 °C, 10 °C, and 2 °C for 24 h. Compared to 26 °C and 10 °C, storage at 2 °C significantly increased the concentrations of lignin, soluble sugar, flavonoids, and phenolics, as well as the accumulation of H2O2, O2-, and thiobarbituric acid reactive substances (TBARS). Additionally, chilling stress inhibited the levels of indoleacetic acid, while enhancing gibberellin, abscisic acid, and jasmonic acid, which may have increased postharvest ginger's adaptation to chilling. Storage at 10 °C decreased lignin concentration and oxidative damage, and induced less fluctuant changes in enzymes and hormones than storage at 2 °C. RNA-seq revealed that the number of differentially expressed genes (DEGs) increased with decreasing temperature. Functional enrichment analysis of the 523 DEGs that exhibited similar expression patterns between all treatments indicated that they were primarily enriched in phytohormone signaling, biosynthesis of secondary metabolites, and cold-associated MAPK signaling pathways. Key enzymes related to 6-gingerol and curcumin biosynthesis were downregulated at 2 °C, suggesting that cold storage may negatively impact ginger quality. Additionally, 2 °C activated the MKK4/5-MPK3/6-related protein kinase pathway, indicating that chilling may increase the risk of ginger pathogenesis.

Gas Flow-Dependent Modification of Plasma Chemistry in μAPP Jet-Generated Cold Atmospheric Plasma and Its Impact on Human Skin Fibroblasts

The micro-scaled Atmospheric Pressure Plasma Jet (µAPPJ) is operated with low carrier gas flows (0.25-1.4 slm), preventing excessive dehydration and osmotic effects in the exposed area. A higher yield of reactive oxygen or nitrogen species (ROS or RNS) in the µAAPJ-generated plasmas (CAP) was achieved, due to atmospheric impurities in the working gas. With CAPs generated at different gas flows, we characterized their impact on physical/chemical changes of buffers and on biological parameters of human skin fibroblasts (hsFB). CAP treatments of buffer at 0.25 slm led to increased concentrations of nitrate (~352 µM), hydrogen peroxide (H₂O₂; ~124 µM) and nitrite (~161 µM). With 1.40 slm, significantly lower concentrations of nitrate (~10 µM) and nitrite (~44 µM) but a strongly increased H₂O₂ concentration (~1265 µM) was achieved. CAP-induced toxicity of hsFB cultures correlated with the accumulated H₂O₂ concentrations (20% at 0.25 slm vs. ~49% at 1.40 slm). Adverse biological consequences of CAP exposure could be reversed by exogenously applied catalase. Due to the possibility of being able to influence the plasma chemistry solely by modulating the gas flow, the therapeutic use of the µAPPJ represents an interesting option for clinical use.

Low temperature plasma suppresses proliferation, invasion, migration and survival of SK-BR-3 breast cancer cells

BACKGROUND

Low temperature plasma (LTP) is a developing field in recent years to play important roles of sterilization, material modification and wound healing. Breast cancer is a common gynecological malignant tumor. Recent studies have shown that LTP is a promising selective anti-cancer treatment. The effect of LTP on breast cancer is still unclear. In this study, We treated breast cancer cell lines with low temperature plasma for different periods of time and analyzed the relevant differences.

METHODS AND RESULTS

SK-BR-3 cell nutrient solution was firstly treated by ACP for 0, 10, 20, 40, 80 and 120 s, which was next used to cultivateSK-BR-3cells for overnight.we found that LTP was able to suppress cell vitality, proliferation, invasion and migration of SK-BR-3 cells. Also, SK-BR-3 apoptosis was induced by LTP in a time-dependent manner.

CONCLUSION

These evidences suggest the negative effect of LTP on malignant development of SK-BR-3 cells, and LTP has the potential clinical application for breast cancer treatment.

Enrichment of Bone Tissue with Antibacterially Effective Amounts of Nitric Oxide Derivatives by Treatment with Dielectric Barrier Discharge Plasmas Optimized for Nitrogen Oxide Chemistry

Cold atmospheric plasmas (CAPs) generated by dielectric barrier discharge (DBD), particularly those containing higher amounts of nitric oxide (NO) or NO derivates (NOD), are attracting increasing interest in medical fields. In the present study, we, for the first time, evaluated DBD-CAP-induced NOD accumulation and therapeutically relevant NO release in calcified bone tissue. This knowledge is of great importance for the development of new therapies against bacterial-infectious complications during bone healing, such as osteitis or osteomyelitis. We found that by modulating the power dissipation in the discharge, it is possible (1) to significantly increase the uptake of NODs in bone tissue, even into deeper regions, (2) to significantly decrease the pH in CAP-exposed bone tissue, (3) to induce a long-lasting and modulable NO production in the bone samples as well as (4) to significantly protect the treated bone tissue against bacterial contaminations, and to induce a strong bactericidal effect in bacterially infected bone samples. Our results strongly suggest that the current DBD technology opens up effective NO-based therapy options in the treatment of local bacterial infections of the bone tissue through the possibility of a targeted modulation of the NOD content in the generated CAPs.

Differential Sensitivity of Melanoma Cells and Their Non-Cancerous Counterpart to Cold Atmospheric Plasma-Induced Reactive Oxygen and Nitrogen Species

Despite continuous progress in therapy, melanoma is one of the most aggressive and malignant human tumors, often relapsing and metastasizing to almost all organs. Cold atmospheric plasma (CAP) is a novel anticancer tool that utilizes abundant reactive oxygen and nitrogen species (RONS) being deposited on the target cells and tissues. CAP-induced differential effects between non-cancerous and cancer cells were comparatively examined. Melanoma and non-cancerous skin fibroblast cells (counterparts; both cell types were isolated from the same patient) were used for plasma-cell interactions. The production of intracellular RONS, such as nitric oxide (NO), hydroxyl radical (•OH), and hydrogen peroxide (H₂O₂), increased remarkably only in melanoma cancer cells. It was observed that cancer cells morphed from spread to round cell shapes after plasma exposure, suggesting that they were more affected than non-cancerous cells in the same plasma condition. Immediately after both cell types were treated with plasma, there were no differences in the amount of extracellular H₂O₂ production, while Hanks' balanced salt solution-containing cancer cells had lower concentrations of H₂O₂ than that of non-cancerous cells at 1 h after treatment. The melanoma cells seemed to respond to CAP treatment with a greater rise in RONS and a higher consumption rate of H₂O₂ than homologous non-cancerous cells. These results suggest that differential sensitivities of non-cancerous skin and melanoma cells to CAP-induced RONS can enable the applicability of CAP in anticancer therapy.

Low-Temperature Plasma-Activated Medium Inhibited Proliferation and Progression of Lung Cancer by Targeting the PI3K/Akt and MAPK Pathways

Low-temperature plasma, an engineered technology to generate various reactive species, is actively studied in cancer treatment in recent years, yet mainly by using a traditional 2D cell culture system. In this study, we explored the effect of the plasma-activated medium (PAM) on lung cancer cells in vitro and in vivo by using a 3D cell culture model. The results showed that PAM markedly inhibited 3D spheroid formation and downregulated stemness-related gene expression. We found that reactive oxygen species (ROS) penetrated throughout the whole spheroids and induced cell death surrounding and in the core of the tumor spheroid. Besides, PAM treatment suppressed migration and invasion of lung cancer cells and downregulated epithelial-mesenchymal transition- (EMT-) related gene expression. In the mouse xenograft model, the tumor volume was significantly smaller in the PAM-treated group compared with the control group. By using transcriptome sequencing, we found that PI3K/Akt and MAPK pathways were involved in the inhibition effects of PAM on lung cancer cells. Therefore, our results indicated that PAM exhibits potential anticancer effects on lung cancer and provides insight into further exploration of PAM-induced cell death and translational preclinical use.

Plasma-Activated Saline Promotes Antibiotic Treatment of Systemic Methicillin-Resistant Staphylococcus aureus Infection

Systemic infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are life-threatening due to their strong multidrug resistance, especially since the biofilms formed by MRSA are more difficult to inactivate by antibiotics, causing long term recurrence of infection. Plasma-activated saline (PAS), a derived form of cold atmospheric-pressure plasma, can effectively inactivate bacteria and cancer cells and has been applied to sterilization and cancer treatment. Previous studies have demonstrated that the pretreatment of MRSA with PAS could promote the action of antibiotics. Here, the PAS was used as an antibiotic adjuvant to promote the inactivation of MRSA biofilms by rifampicin and vancomycin, and the combined treatment reduced approximately 6.0-log₁₀ MRSA cells in biofilms. The plasma-activated saline and rifampicin synergistically and effectively reduced the systemic infection in the murine model. The histochemical analysis and the blood hematological and biochemical test demonstrated that the combined treatment with plasma-activated saline and rifampicin improved the blood hematological and biochemical parameters of infected mice by reducing the infection. Therefore, PAS based on plasma technology represents a new strategy for the treatment of infectious disease caused by multidrug-resistant bacteria and alleviating antibiotic resistance.

Response of Controlled Cell Load Biofilms to Cold Atmospheric Plasma Jet: Evidence of Extracellular Matrix Contribution

Aim: Study of the biocidal effect of a cold atmospheric-pressure plasma in ambient air on single-species bacterial biofilms with controlled cell density, characterized by different extracellular matrices. Methods and results: Two bacterial strains were chosen to present different Gram properties and contrasted extracellular matrices: Pseudomonas aeruginosa ATCC 15442 (Gram-negative), and Leuconostoc citreum NRRL B-1299 (Gram-positive). P. aeruginosa biofilm exhibits a complex matrix, rich in proteins while L. citreum presents the specificity to produce glucan-type exopolysaccharides when grown in the presence of sucrose. Plasma was applied on both surface-spread cells and 24-h grown biofilms with controlled cell loads over 5, 10, or 20 min. Surface-spread bacteria showed a time dependent response, with a maximal bacterial reduction of 2.5 log after 20 min of treatment. On the other hand, in our experimental conditions, no bactericidal effect could be observed when treating biofilms of P. aeruginosa and glucan-rich L. citreum. Conclusions: For biofilms presenting equivalent cell loads, the response to plasma treatment seemed to depend on the properties of the extracellular matrix characterized by infrared spectroscopy, scanning electron microscopy, or dry weight. Significance and impact of study: Both cell load standardization and biofilm characterization are paramount factors to consider the biocide effect of plasma treatments. The extracellular matrix could affect the plasma efficacy by physical and/or chemical protective effects.

Open-Air Cold Plasma Device Leads to Selective Tumor Cell Cytotoxicity

The need for effective and safe therapies for cancer is growing as aging is modifying its epidemiology. Cold atmospheric plasma (CAP) has gained attention as a potential anti-tumor therapy. CAP is a gas with enough energy to ionize a significant fraction of its constituent particles, forming equal numbers of positive ions and electrons. Timely-resolved output voltage measurement, emission spectroscopy, and quantification of reactive species (RS) in plasma-activated media (PAM) were performed to characterize the physical and chemical properties of plasma. To assess the cytotoxicity of cold atmospheric plasma in human tumors, different cell lines were cultured, plated, and exposed to CAP, followed by MTT and SRB colorimetric assays 24 h later. Human fibroblasts, phenotypically normal cells, were processed similarly. Plasma cytotoxicity was higher in cells of breast cancer, urinary bladder cancer, osteosarcoma, lung cancer, melanoma, and endometrial cancer. Cytotoxicity was time-dependent and possibly related to the increased production of hydrogen peroxide in the exposed medium. Sixty seconds of CAP exposure renders selective effects, preserving the viability of fibroblast cells. These results point to the importance of conducting further studies of the therapy with plasma.

The Role of Mitochondria in the Dual Effect of Low-Temperature Plasma on Human Bone Marrow Stem Cells: From Apoptosis to Activation of Cell Proliferation

The potential use of low-temperature plasma (LTP) for therapeutic purposes has aroused the concern of many researchers. This paper examines the effect of LTP on the morphofunctional state of human bone marrow stem cells (BMSC). It has been established that LTP-induced oxidative stress has a dual effect on the state of stem cells. On the one hand, a cell culture exposed to LTP exhibits the progression of a destructive processes, which is manifested by the perturbation of the cell’s morphology, the initiation of lipid peroxidation and the accumulation of products of this process, like diene conjugates and malondialdehyde, as well as the induction of mitochondrial dysfunction, leading to cell death. On the other hand, the effect of LTP on BMSC located at a distance from the plasma is accompanied by the activation of proliferative processes, as evidenced by the tendency of the activity of mitochondrial biogenesis and fission/fusion processes to increase. The paper discusses the role of mitochondria and reactive oxygen species (ROS) in the cellular response to LTP.

Safety and bactericidal efficacy of cold atmospheric plasma generated by a flexible surface Dielectric Barrier Discharge device against Pseudomonas aeruginosa in vitro and in vivo

Background

Cold atmospheric plasma (CAP), which is ionized gas produced at atmospheric pressure, could be a novel and potent antimicrobial therapy for the treatment of infected wounds. Previously we have shown that CAP generated with a flexible surface Dielectric Barrier Discharge (sDBD) is highly effective against bacteria in vitro and in ex vivo burn wound models. In the current paper, we determined the in vitro and in vivo safety and efficacy of CAP generated by this sDBD device.

Methods

The effect of CAP on DNA mutations of V79 fibroblasts was measured using a hypoxanthine–guanine-phosphoribosyltransferase (HPRT) assay. Furthermore, effects on cell proliferation, apoptosis and DNA damage in ex vivo burn wound models (BWMs) were assessed using immunohistochemistry. Next, 10⁵ colony forming units (CFU) P. aeruginosa strain PAO1 were exposed to CAP in a 3D collagen-elastin matrix environment to determine the number of surviving bacteria in vitro. Finally, rat excision wounds were inoculated with 10⁷ CFU PAO1 for 24 h. The wounds received a single CAP treatment, repeated treatments on 4 consecutive days with CAP, 100 µL of 1% (wt/wt) silver sulfadiazine or no treatment. Wound swabs and punch biopsies were taken to determine the number of surviving bacteria.

Results

Exposure of V79 fibroblasts to CAP did not increase the numbers of mutated colonies. Additionally, the number of proliferative, apoptotic and DNA damaged cells in the BWMs was comparable to that of the unexposed control. Exposure of PAO1 to CAP for 2 min resulted in the complete elimination of bacteria in vitro. Contrarily, CAP treatment for 6 min of rat wounds colonized with PAO1 did not effectively reduce the in vivo bacterial count.

Conclusions

CAP treatment was safe but showed limited efficacy against PAO1 in our rat wound infection model.

TRPA1 and TRPV1 channels participate in atmospheric-pressure plasma-induced [Ca2+]i response

Despite successful clinical application of non-equilibrium atmospheric pressure plasma (APP), the details of the molecular mechanisms underlying APP-inducible biological responses remain ill-defined. We previously reported that exposure of 3T3L1 cells to APP-irradiated buffer raised the cytoplasmic free Ca²⁺ ([Ca²⁺]_i) concentration by eliciting Ca²⁺ influx in a manner sensitive to transient receptor potential (TRP) channel inhibitors. However, the precise identity of the APP-responsive channel molecule(s) remains unclear. In the present study, we aimed to clarify channel molecule(s) responsible for indirect APP-responsive [Ca²⁺]_i rises. siRNA-mediated silencing experiments revealed that TRPA1 and TRPV1 serve as the major APP-responsive Ca²⁺ channels in 3T3L1 cells. Conversely, ectopic expression of either TRPA1 or TRPV1 in APP-unresponsive C2C12 cells actually triggered [Ca²⁺]_i elevation in response to indirect APP exposure. Desensitization experiments using 3T3L1 cells revealed APP responsiveness to be markedly suppressed after pretreatment with allyl isothiocyanate or capsaicin, TRPA1 and TRPV1 agonists, respectively. APP exposure also desensitized the cells to these chemical agonists, indicating the existence of a bi-directional heterologous desensitization property of APP-responsive [Ca²⁺]_i transients mediated through these TRP channels. Mutational analyses of key cysteine residues in TRPA1 (Cys421, Cys621, Cys641, and Cys665) and in TRPV1 (Cys258, Cys363, and Cys742) have suggested that multiple reactive oxygen and nitrogen species are intricately involved in activation of the channels via a broad range of modifications involving these cysteine residues. Taken together, these observations allow us to conclude that both TRPA1 and TRPV1 channels play a pivotal role in evoking indirect APP-dependent [Ca²⁺]_i responses.

Emerging Advanced Technologies Developed by IPR for Bio Medical Applications ‑.A Review

Over the last decade, research has intensified worldwide on the use of low-temperature plasmas in medicine and healthcare. Researchers have discovered many methods of applying plasmas to living tissues to deactivate pathogens; to end the flow of blood without damaging healthy tissue; to sanitize wounds and accelerate its healing; and to selectively kill malignant cancer cells. This review paper presents the latest development of advanced and plasma-based technologies used for applications in neurology in particular. Institute for Plasma Research (IPR), an aided institute of the Department of Atomic Energy (DAE), has also developed various technologies in some of these areas. One of these is an Atmospheric Pressure Plasma Jet (APPJ). This device is being studied to treat skin diseases, for coagulation of blood at faster rates and its interaction with oral, lung, and brain cancer cells. In certain cases, in-vitro studies have yielded encouraging results and limited in-vivo studies have been initiated. Plasma activated water has been produced in the laboratory for microbial disinfection, with potential applications in the health sector. Recently, plasmonic nanoparticle arrays which allow detection of very low concentrations of chemicals is studied in detail to allow early-stage detection of diseases. IPR has also been developing AI-based software called DeepCXR and AIBacilli for automated, high-speed screening and detection of footprints of tuberculosis (TB) in Chest X-ray images and for recognizing single/multiple TB bacilli in sputum smear test images, respectively. Deep Learning systems are increasingly being used around the world for analyzing electroencephalogram (EEG) signals for emotion recognition, mental workload, and seizure detection.

Oxidative stress-dependent and -independent death of glioblastoma cells induced by non-thermal plasma-exposed solutions

Non-thermal atmospheric pressure plasma has been widely used for preclinical studies in areas such as wound healing, blood coagulation, and cancer therapy. We previously developed plasma-activated medium (PAM) and plasma-activated Ringer's lactate solutions (PAL) for cancer treatments. Many in vitro and in vivo experiments demonstrated that both PAM and PAL exhibit anti-tumor effects in several types of cancer cells such as ovarian, gastric, and pancreatic cancer cells as well as glioblastoma cells. However, interestingly, PAM induces more intracellular reactive oxygen species in glioblastoma cells than PAL. To investigate the differences in intracellular molecular mechanisms of the effects of PAM and PAL in glioblastoma cells, we measured gene expression levels of antioxidant genes such as CAT, SOD2, and GPX1. Microarray and quantitative real-time PCR analyses revealed that PAM elevated stress-inducible genes that induce apoptosis such as GADD45α signaling molecules. PAL suppressed genes downstream of the survival and proliferation signaling network such as YAP/TEAD signaling molecules. These data reveal that PAM and PAL induce apoptosis in glioblastoma cells by different intracellular molecular mechanisms.

Biological and medical applications of plasma-activated media, water and solutions

Non-thermal atmospheric pressure plasma has been proposed as a new tool for various biological and medical applications. Plasma in close proximity to cell culture media or water creates reactive oxygen and nitrogen species containing solutions known as plasma-activated media (PAM) or plasma-activated water (PAW) - the latter even displays acidification. These plasma-treated solutions remain stable for several days with respect to the storage temperature. Recently, PAM and PAW have been widely studied for many biomedical applications. Here, we reviewed promising reports demonstrating plasma-liquid interaction chemistry and the application of PAM or PAW as an anti-cancer, anti-metastatic, antimicrobial, regenerative medicine for blood coagulation and even as a dental treatment agent. We also discuss the role of PAM on cancer initiation cells (spheroids or cancer stem cells), on the epithelial mesenchymal transition (EMT), and when used for metastasis inhibition considering its anticancer effects. The roles of PAW in controlling plant disease, seed decontamination, seed germination and plant growth are also considered in this review. Finally, we emphasize the future prospects of PAM, PAW or plasma-activated solutions in biomedical applications with a discussion of the mechanisms and the stability and safety issues in relation to humans.

Cold atmospheric pressure plasma for treatment of chronic wounds: drug or medical device?

OBJECTIVE

The use of cold atmospheric pressure plasma (CAPP) as a new therapeutic option to aid the healing of chronic wounds appears promising. Currently, uncertainty exists regarding their classification as medical device or medical drug. Because the classification of CAPP has medical, legal, and economic consequences as well as implications for the level of preclinical and clinical testing, the correct classification is not an academic exercise, but an ethical need.

METHOD

A multidisciplinary team of physicians, surgeons, pharmacists, physicists and lawyers has analysed the physical and technical characteristics as well as legal conditions of the biological action of CAPP.

RESULTS

It was concluded that the mode of action of the locally generated CAPP, with its main active components being different radicals, is pharmacological and not physical in nature.

CONCLUSION

Depending on the intended use, CAPP should be classified as a drug, which is generated by use of a medical device directly at the point of therapeutic application.

New insights of low-temperature plasma effects on germination of three genotypes of Arabidopsis thaliana seeds under osmotic and saline stresses

In order to investigate the effects of low temperature plasmas on germination of Arabidopsis thaliana seeds, a dielectric barrier discharge device generating the plasma in ambient air was used. To highlight the different plasma effects on the seed surface, saline and osmotic stresses were considered in the case of reference Col-0 seeds and two further seed coat mutants gl2 and gpat5 to better analyse the seed surface changes and their consequences on germination. The GL2 gene encode a transcription factor controlling the balance between the biosynthesis of fatty acids in the embryo and the production of mucilage and flavonoid pigments in the seed coat. The GPAT5 gene encode for an acyltransferase necessary for the accumulation of suberin in the seed coat which is essential for the embryo protection. The testa and endosperm ruptures are identified to note the germination stage. An increasing of germination rate, possibly due to the modification of mantle layers structure, is observed in most of cases, even in presence of saline or osmotic stress, after plasma treatment. Furthermore, we demonstrated that the germination rate of the gl2 mutant seeds is increased by at most 47% after plasma treatment, contrariwise, the germination of gpat5 mutant being initially lower is inhibited by the same plasma treatment. The scanning electron microscopy pictures and confocal microscopy fluorescence both showed changes of the exterior aspects of the seeds after plasma treatment. Considering these results, we assumed that lipid compounds can be found on the surface. To validate this hypothesis, permeability tests were performed, and it was clearly shown that a permeability decrease is induced by the low temperature plasma treatment.

Luffa Pretreated by Plasma Oxidation and Acidity to Be Used as Cellulose Films

Cellulose is the most abundant natural polymer on earth. With the increasing shortage of oil resources, people have been focusing more on producing natural cellulose. In this study, guaiacol was used as the model compound to investigate the degradation of lignin in luffa. A new cellulose material was extracted from natural luffa by a pretreatment based on the oxidation and acidity of glow discharge plasma in water. The produced luffa cellulose was dissolved in anhydrous phosphoric/polyphosphoric acid (aPPAC) solvent to prepare cellulose film. Results showed that the reactive species of OH·, HO₂· and H₃O⁺ were produced during the plasma discharge of water. The free radicals ·OH were useful in eliminating lignin by the destruction of aromatic structure, whereas H₃O⁺ in eliminating hemicellulose in the luffa raw material. At the conditions of luffa powder concentration of 9.26 g/L, discharge time of 20 min, and plasma power of 100W, the cellulose component was increased to 81.2%. After 25 min, the luffa cellulose was completely dissolved in the aPPAC solvent at 0–5 °C. Thus, a regenerated cellulose film of cellulose II was prepared. The aPPAC solvent was a good non-derivatizing solvent for the luffa cellulose. The regenerated film exhibited good mechanical properties, wettability and a compact structure. Therefore, plasma pretreatment was an environmentally friendly and high-efficiency method for luffa degumming. The luffa cellulose can be well used in dissolution and regeneration in films.

Plasma Farming: Non-Thermal Dielectric Barrier Discharge Plasma Technology for Improving the Growth of Soybean Sprouts and Chickens

Non-thermal dielectric barrier discharge (DBD) plasma is an innovative and emerging field combining plasma physics, life science and clinical medicine for a wide-range of biological applications. Plasma techniques are applied in treating surfaces, materials or devices to realize specific qualities for subsequent special medical applications, plant seeds to improve the production and quality of crops, and living cells or tissues to realize therapeutic effects. Several studies that are summarized within this review show that non-thermal DBD plasma technique has potential biological applications in soybean sprout growth, chicken embryonic development and postnatal growth rate, and even male chicken reproductive capacity. The current developments in the non-thermal DBD plasma technique may be beneficial to improve plant and poultry productivity.

Effects of low temperature plasmas and plasma activated waters on Arabidopsis thaliana germination and growth

Two plasma devices at atmospheric pressure (air dielectric barrier discharge and helium plasma jet) have been used to study the early germination of Arabidopsis thaliana seeds during the first days. Then, plasma activated waters are used during the later stage of plant development and growth until 42 days. The effects on both testa and endospserm ruptures during the germination stage are significant in the case of air plasma due to its higher energy and efficiency of producing reactive oxygen species than the case of helium plasma. The latter has shown distinct effects only for testa rupture. Analysis of germination stimulations are based on specific stainings for reactive oxygen species production, peroxidase activity and also membrane permeability tests. Furthermore, scanning electron microscopy (SEM) has shown a smoother seed surface for air plasma treated seeds that can explain the plasma induced-germination. During the growth stage, plants were watered using 4 kinds of water (tap and deionized waters activated or not by the low temperature plasma jet). With regards to other water kinds, the characterization of the tap water has shown a larger conductivity, acidity and concentration of reactive nitrogen and oxygen species. Only the tap water activated by the plasma jet has shown a significant effect on the plant growth. This effect could be correlated to reactive nitrogen species such as nitrite/nitrate species present in plasma activated tap water.

Sterilization of Biofilm on a Titanium Surface Using a Combination of Nonthermal Plasma and Chlorhexidine Digluconate

Nosocomial infections caused by opportunistic bacteria pose major healthcare problem worldwide. Out of the many microorganisms responsible for such infections, Pseudomonas aeruginosa is a ubiquitous bacterium that accounts for 10-20% of hospital-acquired infections. These infections have mortality rates ranging from 18 to 60% and the cost of treatment ranges from $20,000 to $80,000 per infection. The formation of biofilms on medical devices and implants is responsible for the majority of those infections. Only limited progress has been made to prevent this issue in a safe and cost-effective manner. To address this, we propose employing jet plasma to break down and inactivate biofilms in vitro. Moreover, to improve the antimicrobial effect on the biofilm, a treatment method using a combination of jet plasma and a biocide known as chlorhexidine (CHX) digluconate was investigated. We found that complete sterilization of P. aeruginosa biofilms can be achieved after combinatorial treatment using plasma and CHX. A decrease in biofilm viability was also observed using confocal laser scanning electron microscopy (CLSM). This treatment method sterilized biofilm-contaminated surfaces in a short treatment time, indicating it to be a potential tool for the removal of biofilms present on medical devices and implants.

The protective action of osmolytes on the deleterious effects of gamma rays and atmospheric pressure plasma on protein conformational changes

Both gamma rays and atmospheric pressure plasma are known to have anticancer properties. While their mechanism actions are still not clear, in some contexts they work in similar manner, while in other contexts they work differently. So to understand these relationships, we have studied Myoglobin protein after the treatment of gamma rays and dielectric barrier discharge (DBD) plasma, and analyzed the changes in thermodynamic properties and changes in the secondary structure of protein after both treatments. The thermodynamic properties were analyzed using chemical and thermal denaturation after both treatments. We have also studied the action of gamma rays and DBD plasma on myoglobin in the presence of osmolytes, such as sorbitol and trehalose. For deep understanding of the action of gamma rays and DBD plasma, we have analyzed the reactive species generated by them in buffer at all treatment conditions. Finally, we have used molecular dynamic simulation to understand the hydrogen peroxide action on myoglobin with or without osmolytes, to gain deeper insight into how the osmolytes can protect the protein structure from the reactive species generated by gamma rays and DBD plasma.

Novel Intraperitoneal Treatment With Non-Thermal Plasma-Activated Medium Inhibits Metastatic Potential of Ovarian Cancer Cells

Non-thermal atmospheric pressure plasma has been proposed as a new therapeutic tool for cancer treatment. Recently, plasma-activated medium (PAM) has been widely studied in various cancer types. However, there are only few reports demonstrating the anti-tumour effects of PAM in an animal model reflecting pathological conditions and the accompanying mechanism. Here we investigated the inhibitory effect of PAM on the metastasis of ovarian cancer ES2 cells in vitro and in vivo. We demonstrated that ES2 cell migration, invasion and adhesion were suppressed by PAM at a certain PAM dilution ratio, whereas cell viability remained unaffected. In an in vivo mouse model of intraperitoneal metastasis, PAM inhibited peritoneal dissemination of ES2 cells, resulting in prolonged survival. Moreover, we assessed the molecular mechanism and found that MMP-9 was decreased by PAM. On further investigation, we also found that PAM prevented the activation of the MAPK pathway by inhibiting the phosphorylation of JNK1/2 and p38 MAPK. These findings indicate that PAM inhibits the metastasis of ovarian cancer cells through reduction of MMP-9 secretion, which is critical for cancer cell motility. Our findings suggest that PAM intraperitoneal therapy may be a promising treatment option for ovarian cancer.

A Novel Micro Cold Atmospheric Plasma Device for Glioblastoma Both In Vitro and In Vivo

Cold atmospheric plasma (CAP) treatment is a rapidly expanding and emerging technology for cancer treatment. Direct CAP jet irradiation is limited to the skin and it can also be invoked as a supplement therapy during surgery as it only causes cell death in the upper three to five cell layers. However, the current cannulas from which the plasma emanates are too large for intracranial applications. To enhance efficiency and expand the applicability of the CAP method for brain tumors and reduce the gas flow rate and size of the plasma jet, a novel micro-sized CAP device (µCAP) was developed and employed to target glioblastoma tumors in the murine brain. Various plasma diagnostic techniques were applied to evaluate the physics of helium µCAP such as electron density, discharge voltage, and optical emission spectroscopy (OES). The direct and indirect effects of µCAP on glioblastoma (U87MG-RedFluc) cancer cells were investigated in vitro. The results indicate that µCAP generates short- and long-lived species and radicals (i.e., hydroxyl radical (•OH), hydrogen peroxide (H₂O₂), and nitrite (NO₂⁻), etc.) with increasing tumor cell death in a dose-dependent manner. Translation of these findings to an in vivo setting demonstrates that intracranial µCAP is effective at preventing glioblastoma tumor growth in the mouse brain. The µCAP device can be safely used in mice, resulting in suppression of tumor growth. These initial observations establish the µCAP device as a potentially useful ablative therapy tool in the treatment of glioblastoma.

Medical applications of non-thermal atmospheric pressure plasma

An innovative approach for producing reactive oxygen and nitrogen species is the use of non-thermal atmospheric pressure plasma. The technique has been applied in a wide variety of fields ranging from the micro-fabrication of electric devices to the treatment of disease. Although non-thermal atmospheric pressure plasmas have been shown to be clinically beneficial for wound healing, blood coagulation, and cancer treatment, the underlying molecular mechanisms are poorly understood. In this review, we describe the current progress in plasma medicine, with a particular emphasis on plasma-activated medium (PAM), which is a solution that is irradiated with a plasma and has broadened the applications of plasmas in medicine.

Impact of an ionic liquid on protein thermodynamics in the presence of cold atmospheric plasma and gamma rays

TEMS IL can protect proteins against the reactive species generated by gamma rays and plasma.

Medical applications of non-thermal atmospheric pressure plasma

An innovative approach for producing reactive oxygen and nitrogen species is the use of non-thermal atmospheric pressure plasma. The technique has been applied in a wide variety of fields ranging from the micro-fabrication of electric devices to the treatment of disease. Although non-thermal atmospheric pressure plasmas have been shown to be clinically beneficial for wound healing, blood coagulation, and cancer treatment, the underlying molecular mechanisms are poorly understood. In this review, we describe the current progress in plasma medicine, with a particular emphasis on plasma-activated medium (PAM), which is a solution that is irradiated with a plasma and has broadened the applications of plasmas in medicine.

Non-thermal atmospheric pressure plasma activates lactate in Ringer's solution for anti-tumor effects

Non-thermal atmospheric pressure plasma is a novel approach for wound healing, blood coagulation, and cancer therapy. A recent discovery in the field of plasma medicine is that non-thermal atmospheric pressure plasma not only directly but also indirectly affects cells via plasma-treated liquids. This discovery has led to the use of non-thermal atmospheric pressure plasma as a novel chemotherapy. We refer to these plasma-treated liquids as plasma-activated liquids. We chose Ringer’s solutions to produce plasma-activated liquids for clinical applications. In vitro and in vivo experiments demonstrated that plasma-activated Ringer’s lactate solution has anti-tumor effects, but of the four components in Ringer’s lactate solution, only lactate exhibited anti-tumor effects through activation by non-thermal plasma. Nuclear magnetic resonance analyses indicate that plasma irradiation generates acetyl and pyruvic acid-like groups in Ringer’s lactate solution. Overall, these results suggest that plasma-activated Ringer’s lactate solution is promising for chemotherapy.

Combination of cold atmospheric plasma and iron nanoparticles in breast cancer: gene expression and apoptosis study

Background

Current cancer treatments have unexpected side effects of which the death of normal cells is one. In some cancers, iron nanoparticles (NPs) can be subjected to diagnosis and passive targeting treatment. Cold atmospheric plasma (CAP) has a proven induction of selective cell death ability. In this study, we have attempted to analyze the synergy between CAP and iron NPs in human breast adenocarcinoma cells (MCF-7).

Materials and methods

In vitro cytotoxicity of CAP treatment and NPs in cells measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and cell death was shown by 4′,6-diamidino-2-phenylindole and annexin V staining. Fluctuations in BAX and BCL-2 gene expression were investigated by means of real-time polymerase chain reaction.

Results

MTT assay results showed that combination of plasma and iron NPs decreased the viability of cancer cells significantly (P<0.05). Real-time analysis showed that the combination therapy induced shifting the BAX/BCL-2 ratio in favor of apoptosis.

Conclusion

Our data indicate that synergy between CAP and iron NPs can be applied in breast cancer treatment selectively.

Short and long time effects of low temperature Plasma Activated Media on 3D multicellular tumor spheroids

This work investigates the regionalized antiproliferative effects of plasma-activated medium (PAM) on colon adenocarcinoma multicellular tumor spheroid (MCTS), a model that mimics 3D organization and regionalization of a microtumor region. PAM was generated by dielectric barrier plasma jet setup crossed by helium carrier gas. MCTS were transferred in PAM at various times after plasma exposure up to 48 hours and effect on MCTS growth and DNA damage were evaluated. We report the impact of plasma exposure duration and delay before transfer on MCTS growth and DNA damage. Local accumulation of DNA damage revealed by histone H2AX phosphorylation is observed on outermost layers and is dependent on plasma exposure. DNA damage is completely reverted by catalase addition indicating that H₂O₂ plays major role in observed genotoxic effect while growth inhibitory effect is maintained suggesting that it is due to others reactive species. SOD and D-mannitol scavengers also reduced DNA damage by 30% indicating that and OH^* are involved in H₂O₂ formation. Finally, PAM is able to retain its cytotoxic and genotoxic activity upon storage at +4 °C or −80 °C. These results suggest that plasma activated media may be a promising new antitumor strategy for colorectal cancer tumors.

Cold atmospheric plasma jet-generated RONS and their selective effects on normal and carcinoma cells

Cold atmospheric helium plasma jets were fabricated and utilized for plasma-cell interactions. The effect of operating parameters and jet design on the generation of specific reactive oxygen and nitrogen species (RONS) within cells and cellular response were investigated. It was found that plasma treatment induced the overproduction of RONS in various cancer cell lines selectively. The plasma under a relatively low applied voltage induced the detachment of cells, a reduction in cell viability, and apoptosis, while the plasma under higher applied voltage led to cellular necrosis in our case. To determine whether plasma-induced reactive oxygen species (ROS) generation occurs through interfering with mitochondria-related cellular response, we examined the plasma effects on ROS generation in both parental A549 cells and A549 ρ(0) cells. It was observed that cancer cells were more susceptible to plasma-induced RONS (especially nitric oxide (NO) and nitrogen dioxide (NO2(-)) radicals) than normal cells, and consequently, plasma induced apoptotic cell responses mainly in cancer cells.

Effectiveness of plasma treatment on gastric cancer cells

BACKGROUND

Treatment of peritoneal carcinomatosis arising from gastric cancer remains a considerable challenge. In recent years, the anticancer effect of nonequilibrium atmospheric pressure plasma (NEAPP) has been reported in several cancer cell lines. Use of NEAPP may develop into a new class of anticancer therapy that augments surgery, chemotherapy, and radiotherapy.

METHOD

Gastric cancer cells were assessed for changes in cell morphology and rate of proliferation after treatment with NEAPP-exposed medium (PAM). To explore the functional mechanism, caspase 3/7, annexin V, and uptake of reactive oxygen species (ROS) were evaluated, along with the effect of the ROS scavenger N-acetylcysteine (NAC).

RESULTS

PAM treatment for 24 h affected cell morphology, suggestive of induction of apoptosis. PAM cytotoxicity was influenced by the time of exposure to PAM, the type of cell line, and the number of cells seeded. Cells treated with PAM for 2 h demonstrated activated caspase 3/7 and an increased proportion of annexin V-positive cells compared with untreated cells. Additionally, ROS uptake was observed in PAM-treated cells, whereas NAC reduced the cytotoxicity induced by PAM presumably through reduction of ROS uptake. Furthermore, CD44 variant 9, which reportedly leads to glutathione synthesis and suppresses stress signaling of ROS, was overexpressed in PAM-resistant cells.

CONCLUSIONS

PAM treatment induced apoptosis of gastric cancer cells through generation and uptake of ROS. Local administration of PAM could develop into an option to treat peritoneal carcinomatosis.

Nonthermal plasma--A tool for decontamination and disinfection

By definition, the nonthermal plasma (NTP) is partially ionized gas where the energy is stored mostly in the free electrons and the overall temperature remains low. NTP is widely used for many years in various applications such as low-temperature plasma chemistry, removal of gaseous pollutants, in gas-discharge lamps or surface modification. However, during the last ten years, NTP usage expanded to new biological areas of application like plasma microorganisms' inactivation, ready-to-eat food preparation, biofilm degradation or in healthcare, where it seems to be important for the treatment of cancer cells and in the initiation of apoptosis, prion inactivation, prevention of nosocomial infections or in the therapy of infected wounds. These areas are presented and documented in this paper as a review of representative publications.

Plasma-activated medium suppresses choroidal neovascularization in mice: a new therapeutic concept for age-related macular degeneration

Choroidal neovascularization (CNV) is the main pathogenesis of age-related macular degeneration (AMD), which leads to severe vision loss in many aged patients in most advanced country. CNV compromises vision via hemorrhage and retinal detachment on account of pathological neovascularization penetrating the retina. Plasma medicine represents the medical application of ionized gas “plasma” that is typically studied in the field of physical science. Here we examined the therapeutic ability of plasma-activated medium (PAM) to suppress CNV. The effect of PAM on vascularization was assessed on the basis of human retinal endothelial cell (HREC) tube formation. In mice, laser photocoagulation was performed to induce CNV (laser-CNV), followed by intravitreal injection of PAM. N-Acetylcysteine was used to examine the role of reactive oxygen species in PAM-induced CNV suppression. Fundus imaging, retinal histology examination, and electroretinography (ERG) were also performed to evaluate PAM-induced retinal toxicity. Interestingly, HREC tube formation and laser-CNV were both reduced by treatment with PAM. N-acetylcysteine only partly neutralized the PAM-induced reduction in laser-CNV. In addition, PAM injection had no effect on regular retinal vessels, nor did it show retinal toxicity in vivo. Our findings indicate the potential of PAM as a novel therapeutic agent for suppressing CNV.

Cell death induced by ozone and various non-thermal plasmas: therapeutic perspectives and limitations

Non-thermal plasma has been recognized as a promising tool across a vast variety of biomedical applications, with the potential to create novel therapeutic methods. However, the understanding of the molecular mechanisms behind non-thermal plasma cellular effects remains a significant challenge. In this study, we show how two types of different non-thermal plasmas induce cell death in mammalian cell cultures via the formation of multiple intracellular reactive oxygen/nitrogen species. Our results showed a discrepancy in the superoxide accumulation and lysosomal activity in response to air and helium plasma, suggesting that triggered signalling cascades might be grossly different between different plasmas. In addition, the effects of ozone, a considerable component of non-thermal plasma, have been simultaneously evaluated and have revealed much faster and higher cytotoxic effects. Our findings offer novel insight into plasma-induced cellular responses, and provide a basis for better controlled biomedical applications.

Retardation of C2C12 myoblast cell proliferation by exposure to low-temperature atmospheric plasma

As the first step in evaluating the possibility of low-temperature atmospheric plasma for clinical applications in the treatment of rhabdomyosarcoma (RMS), we determined the effects of plasma exposure on C2C12 myoblasts. The low-temperature atmospheric plasma was generated through an electrical discharge in argon gas. One minute of plasma exposure every 24 h inhibited the cell proliferation, whereas myoblast differentiation was not affected. Plasma exposure increased the phosphorylation of ERK and JNK at 30 min after the exposure, but the phosphorylation of both was decreased to less than control levels at 1 and 4 h after the exposure. Plasma exposure increased the percentage of cells in the G2/M phase at 8 h after the exposure. In conclusion, plasma exposure retarded the proliferation of C2C12 myoblasts by G2/M arrest. Therefore, plasma exposure can be a possible treatment for the anti-proliferative effects of malignant tumors, such as RMS, without affecting differentiated skeletal muscle cells.

Ab initio transport coefficients of Ar⁺ ions in Ar for cold plasma jet modeling

Collision cross sections and transport coefficients are calculated for Ar{+} ions, in the ground state {2}P_{3/2} and in the metastable state {2}P_{1/2}, colliding with their parent gas. Differential and integral collision cross sections are obtained using a numerical integration of the nuclear Schrödinger equation for several published interaction potentials. The Cohen-Schneider semi-empirical model is used for the inclusion of the spin-orbit interaction. The corresponding differential collision cross sections are then used in an optimized Monte Carlo code to calculate the ion transport coefficients for each initial ion state over a wide range of reduced electric field. Ion swarm data results are then compared with available experimental data for different proportions of ions in each state. This allows us to identify the most reliable interaction potential which reproduces ion transport coefficients falling within the experimental error bars. Such ion transport data will be used in electrohydrodynamic and chemical kinetic models of the low temperature plasma jet to quantify and to tune the active species production for a better use in biomedical applications.

The effect of tuning cold plasma composition on glioblastoma cell viability

Previous research in cold atmospheric plasma (CAP) and cancer cell interaction has repeatedly proven that the cold plasma induced cell death. It is postulated that the reactive oxygen species (ROS) and reactive nitrogen species (RNS) play a major role in the CAP cancer therapy. In this paper, we seek to determine a mechanism of CAP therapy on glioblastoma cells (U87) through an understanding of the composition of the plasma, including treatment time, voltage, flow-rate and plasma-gas composition. In order to determine the threshold of plasma treatment on U87, normal human astrocytes (E6/E7) were used as the comparison cell line. Our data showed that the 30 sec plasma treatment caused 3-fold cell death in the U87 cells compared to the E6/E7 cells. All the other compositions of cold plasma were performed based on this result: plasma treatment time was maintained at 30 s per well while other plasma characteristics such as voltage, flow rate of source gas, and composition of source gas were changed one at a time to vary the intensity of the reactive species composition in the plasma jet, which may finally have various effect on cells reflected by cell viability. We defined a term “plasma dosage” to summarize the relationship of all the characteristics and cell viability.

Effect of indirect nonequilibrium atmospheric pressure plasma on anti-proliferative activity against chronic chemo-resistant ovarian cancer cells in vitro and in vivo

PURPOSE

Nonequilibrium atmospheric pressure plasma (NEAPP) therapy has recently been focused on as a novel medical practice. Using cells with acquired paclitaxel/cisplatin resistance, we elucidated effects of indirect NEAPP-activated medium (NEAPP-AM) exposure on cell viability and tumor growth in vitro and in vivo.

METHODS

Using chronic paclitaxel/cisplatin-resistant ovarian cancer cells, we applied indirect NEAPP-exposed medium to cells and xenografted tumors in a mouse model. Furthermore, we examined the role of reactive oxygen species (ROS) or their scavengers in the above-mentioned EOC cells.

RESULTS

We assessed the viability of NOS2 and NOS3 cells exposed to NEAPP-AM, which was prepared beforehand by irradiation with NEAPP for the indicated time. In NOS2 cells, viability decreased by approximately 30% after NEAPP-AM 120-sec treatment (P<0.01). The growth-inhibitory effects of NEAPP-AM were completely inhibited by N-acetyl cysteine treatment, while L-buthionine-[S, R]-sulfoximine, an inhibitor of the ROS scavenger used with NEAPP-AM, decreased cell viability by 85% after NEAPP-AM 60-sec treatment(P<0.05) and by 52% after 120 sec, compared to the control (P<0.01). In the murine subcutaneous tumor-formation model, NEAPP-AM injection resulted in an average inhibition of the NOS2 cell-inoculated tumor by 66% (P<0.05) and NOS2TR cell-inoculated tumor by 52% (P<0.05), as compared with the control.

CONCLUSION

We demonstrated that plasma-activated medium also had an anti-tumor effect on chemo-resistant cells in vitro and in vivo. Indirect plasma therapy is a promising treatment option for EOC and may contribute to a better patient prognosis in the future.