Cold Atmospheric Plasma Is a Potent Tool to Improve Chemotherapy in Melanoma In Vitro and In Vivo

Comparing Redox and Intracellular Signalling Responses to Cold Plasma in Wound Healing and Cancer

Cold plasma (CP) is an ionised gas containing excited molecules and ions, radicals, and free electrons, and which emits electric fields and UV radiation. CP is potently antimicrobial, and can be applied safely to biological tissue, birthing the field of plasma medicine. Reactive oxygen and nitrogen species (RONS) produced by CP affect biological processes directly or indirectly via the modification of cellular lipids, proteins, DNA, and intracellular signalling pathways. CP can be applied at lower levels for oxidative eustress to activate cell proliferation, motility, migration, and antioxidant production in normal cells, mainly potentiated by the unfolded protein response, the nuclear factor-erythroid factor 2-related factor 2 (Nrf2)-activated antioxidant response element, and the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) pathway, which also activates nuclear factor-kappa B (NFκB). At higher CP exposures, inactivation, apoptosis, and autophagy of malignant cells can occur via the degradation of the PI3K/Akt and mitogen-activated protein kinase (MAPK)-dependent and -independent activation of the master tumour suppressor p53, leading to caspase-mediated cell death. These opposing responses validate a hormesis approach to plasma medicine. Clinical applications of CP are becoming increasingly realised in wound healing, while clinical effectiveness in tumours is currently coming to light. This review will outline advances in plasma medicine and compare the main redox and intracellular signalling responses to CP in wound healing and cancer.

Cold atmospheric plasma sensitizes melanoma cells to targeted therapy agents in vitro

Cold atmospheric plasma (CAP) has been reported to kill melanoma cells in vitro and in vivo. BRAF and MEK inhibitors are targeted therapy agents for advanced melanoma patients with BRAF mutations. However, low overall survival and relapse-free survival are still tough challenges due to drug resistance. In this study, we confirmed that CAP alleviated innate drug resistance and promoted the anti-tumor effect of targeted therapy in A875 and WM115 melanoma cells in vitro. Further, we revealed that CAP altered the expression of various molecules concerning MAPK and PI3K-AKT pathways in A875 cells. This study demonstrates that CAP promises to work as adjuvant treatment with targeted therapy to overcome drug resistance for malignant tumors in future.

Engineering alginate-based injectable hydrogels combined with bioactive polymers for targeted plasma-derived oxidative stress delivery in osteosarcoma therapy

Reactive Oxygen and Nitrogen Species (RONS) in biological systems display hormetic effects, capable of either promoting cell regenerative effects or inducing cell death. Recently, hydrogels have emerged as a promising delivery platform for RONS generated from Cold Atmospheric Plasmas (CAP), known as Plasma-Treated Hydrogels (PTH). PTH have been proposed as an alternative therapy to conventional cancer treatments, offering reduced side effects through the controlled and localized delivery of plasma-derived RONS. In this work, we have developed alginate-based PTH with dual therapeutic action provided by plasma-derived RONS acting as selective anticancer agents for osteosarcoma treatment, and biomolecules (hyaluronic acid and gelatin) to promote stem cell-mediated bone regeneration. For this purpose, we designed a novel manufacturing process to maximize the load of plasma-derived RONS within the PTH. Then, we assessed the PTH bioactivity on osteosarcoma MG-63 cells, and human mesenchymal stem cells (hMSCs). The results showed that the PTH composed of 0.25 % alginate +1 % hyaluronic acid is the most promising formulation in osteosarcoma treatment, showing a dual-action bioactivity as a selective cytotoxic anticancer agent, and as promoter of the proliferation and osteogenic differentiation of hMSCs. These findings provide strong evidence of the significant potential of PTH in the oncological field.

Short-term Effects of Non-invasive Physical Plasma Treatment on Genomic Stability

BACKGROUND/AIM

The application of non-invasive physical plasma (NIPP) generates reactive oxygen species. These can lead to chemical oxidation of cellular molecules including DNA. On the other hand, NIPP can induce therapeutically intended apoptosis, which also leads to DNA fragmentation in the late phase. Therefore, to assess unwanted genotoxic effects, the formation of DNA damage was investigated in this study in discrimination from apoptotic processes.

MATERIALS AND METHODS

Mutation events after NIPP application were analyzed in CCL-93 fibroblast cells using the hypoxanthine phosphoribosyl transferase assay. Additionally, DNA single-strand breaks (SSB) and double-strand breaks (DSB) were quantified by performing the alkaline comet assay, and terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. DSBs were quantified by phospho-histone 2AX-p53-binding protein 1 co-localization DSB focus assay. The data were compared with cell death quantification by the caspase-3/7 apoptosis assay.

RESULTS

Treatment with NIPP led to exceedingly rapid damage to genomic DNA and the appearance of DNA SSBs and DSBs in the initial 4 h. However, damage decreased again within the first 4-8 h, then the late phase began, characterized by DNA DSB and increasing caspase-3/7 activation.

CONCLUSION

Although NIPP treatment leads to extremely rapid damage to genomic DNA, this damage is reversed very quickly by efficient DNA-repair processes. As a consequence, only those cells whose genome damage can be repaired actually survive and proliferate. Persistent genotoxic effects were not observed in the cell system used.

Effect of cold atmospheric plasma on changing of biomolecular structures involved in apoptosis pathways of melanoma cancer

BACKGROUND

Cold atmospheric plasma (CAP), is a technology based on non-thermal ionized gas that is used for cancer therapy in research. We evaluated the effect of CAP on malignant melanoma cancer cell line (B16) in comparison with normal cells (L929).

METHODS

The effect of CAP on the cytotoxicity of B16 and L929 cell lines was assayed by the MTT method and inverted microscopy. The induction of apoptosis in cells was evaluated using a fluorescence microscope. FTIR monitored the CAP effect in biomacromolecules changes in these cell lines. QPCR assayed gene expression of BAX, BCL-2, and Caspase-3 (CASP-3).

RESULTS

The results of the MTT test showed CAP has a cytotoxic effect on the B16 cancer cell line more than L929 normal cells (p < 0.0001). The results of invert and fluorescence microscopy showed CAP-induced apoptotic morphology on cancerous cells. FTIR spectroscopy indicated CAP changes biomacromolecules structure. Evaluation of gene expression showed CAP increased BAX and CASP-3 gene expression. Also, it decreased BCL-2 gene expression.

CONCLUSIONS

Taken together, CAP may change biomacromolecule structures involved in apoptosis pathways, decrease proliferation and induce apoptosis in cancer cells.

Medical Gas Plasma Technology Combines with Antimelanoma Therapies and Promotes Immune-Checkpoint Therapy Responses

Strategies to improve activity and selectivity are major goals in oncological drug development. Medical gas plasma therapy has been subject to intense research in dermatooncology recently. Based on partial gas ionization, this approach is exceptional in generating a variety of reactive oxygen species simultaneously that can be applied locally at the tumor side. It is hypothesized that combined gas plasma treatment can potentiate drug responses in the treatment of melanoma. Using a plasma jet approved as medical device in Europe, a systematic screening of 46 mitochondria-targeted drugs identifies five agents synergizing in vitro and in vivo. Increased intratumoral leucocyte infiltration points to immunomodulatory aspects of the treatment, motivating to investigate responses to immune checkpoint blockade in combination with plasma. Tumor growth is monitored based on bioluminescent imaging, and single-cell suspensions are retrieved from each tumor to characterize tumor-infiltrating leucocytes using multicolor flow cytometry. Gene expression profiling is done using a validated NanoString panel targeting 770 genes specifically designed for immuno-oncological research. Cell type abundancies are characterized from bulk RNA samples using the CIBERSORT computational framework. Collectively, the results indicate that local application of medical gas plasma technology synergizes with mitochondria-targeted drugs and anti-PD1 checkpoint therapy in treating melanoma.

Medical gas plasma technology: Roadmap on cancer treatment and immunotherapy

Despite continuous therapeutic progress, cancer remains an often fatal disease. In the early 2010s, first evidence in rodent models suggested promising antitumor action of gas plasma technology. Medical gas plasma is a partially ionized gas depositing multiple physico-chemical effectors onto tissues, especially reactive oxygen and nitrogen species (ROS/RNS). Today, an evergrowing body of experimental evidence suggests multifaceted roles of medical gas plasma-derived therapeutic ROS/RNS in targeting cancer alone or in combination with oncological treatment schemes such as ionizing radiation, chemotherapy, and immunotherapy. Intriguingly, gas plasma technology was recently unraveled to have an immunological dimension by inducing immunogenic cell death, which could ultimately promote existing cancer immunotherapies via in situ or autologous tumor vaccine schemes. Together with first clinical evidence reporting beneficial effects in cancer patients following gas plasma therapy, it is time to summarize the main concepts along with the chances and limitations of medical gas plasma onco-therapy from a biological, immunological, clinical, and technological point of view.

Current Status and Future Trends of Cold Atmospheric Plasma as an Oncotherapy

Cold atmospheric plasma (CAP), a redox modulation tool, is capable of inhibiting a wide spectrum of cancers and has thus been proposed as an emerging onco-therapy. However, with incremental successes consecutively reported on the anticancer efficacy of CAP, no consensus has been made on the types of tumours sensitive to CAP due to the different intrinsic characteristics of the cells and the heterogeneous design of CAP devices and their parameter configurations. These factors have substantially hindered the clinical use of CAP as an oncotherapy. It is thus imperative to clarify the tumour types responsive to CAP, the experimental models available for CAP-associated investigations, CAP administration strategies and the mechanisms by which CAP exerts its anticancer effects with the aim of identifying important yet less studied areas to accelerate the process of translating CAP into clinical use and fostering the field of plasma oncology.

Cold atmospheric nitrogen plasma induces metal-initiated cell death by cell membrane rupture and mitochondrial perturbation

Cold atmospheric plasma (CAP) is a novel biomedical tool used for cancer therapy. A device using nitrogen gas (N2 CAP) produced CAP that induced cell death through the production of reactive nitrogen species and an increase in intracellular calcium. In this study, we investigated the effect of N2 CAP-irradiation on cell membrane and mitochondrial function in human embryonic kidney cell line 293T. We investigated whether iron is involved in N2 CAP-induced cell death, as deferoxamine methanesulfonate (an iron chelator) inhibits this process. We found that N2 CAP induced cell membrane disturbance and loss of mitochondrial membrane potential in an irradiation time-dependent manner. BAPTA-AM, a cell-permeable calcium chelator, inhibited N2 CAP-induced loss of mitochondrial membrane potential. These results suggest that disruption of intracellular metal homeostasis was involved in N2 CAP-induced cell membrane rupture and mitochondrial dysfunction. Moreover, N2 CAP irradiation generated a time-dependent production of peroxynitrite. However, lipid-derived radicals are unrelated to N2 CAP-induced cell death. Generally, N2 CAP-induced cell death is driven by the complex interaction between metal movement and reactive oxygen and nitrogen species produced by N2 CAP.

Low-Temperature Plasma-Activated Medium Inhibits the Migration of Non-Small Cell Lung Cancer Cells via the Wnt/β-Catenin Pathway

This study explored the molecular mechanism of the plasma activation medium (PAM) inhibiting the migration ability of NSCLC (non-small cell lung cancer) cells. The effect of PAM incubation on the cell viability of NSCLC was detected through a cell viability experiment. Transwell cells and microfluidic chips were used to investigate the effects of PAM on the migration capacity of NSCLC cells, and the latter was used for the first time to observe the changes in the migration capacity of cancer cells treated with PAM. Moreover, the molecular mechanisms of PAM affecting the migration ability of NSCLC cells were investigated through intracellular and extracellular ROS detection, mitochondrial membrane potential, and Western blot experiments. The results showed that after long-term treatment with PAM, the high level of ROS produced by PAM reduced the level of the mitochondrial membrane potential of cells and blocked the cell division cycle in the G2/M phase. At the same time, the EMT process was reversed by inhibiting the Wnt/β-catenin signaling pathway. These results suggested that the high ROS levels generated by the PAM treatment reversed the EMT process by inhibiting the WNT/β-catenin pathway in NSCLC cells and thus inhibited the migration of NSCLC cells. Therefore, these results provide good theoretical support for the clinical treatment of NSCLC with PAM.

Cold Atmospheric Plasma-Activated Composite Hydrogel for an Enhanced and On-Demand Delivery of Antimicrobials

We present the concept of a versatile drug-loaded composite hydrogel that can be activated using an argon-based cold atmospheric plasma (CAP) jet to deliver both a drug and CAP-generated molecules, concomitantly, in a tissue target. To demonstrate this concept, we utilized the antibiotic gentamicin that is encapsulated in sodium polyacrylate (PAA) particles, which are dispersed within a poly(vinyl alcohol) (PVA) hydrogel matrix. The final product is a gentamicin-PAA-PVA composite hydrogel suitable for an on-demand triggered release using CAP. We show that by activating using CAP, we can effectively release gentamicin from the hydrogel and also eradicate the bacteria effectively, both in the planktonic state and within a biofilm. Besides gentamicin, we also successfully demonstrate the applicability of the CAP-activated composite hydrogel loaded with other antimicrobial agents such as cetrimide and silver. This concept of a composite hydrogel is potentially adaptable to a range of therapeutics (such as antimicrobials, anticancer agents, and nanoparticles) and activatable using any dielectric barrier discharge CAP device.

The Regulatory Mechanism of Cold Plasma in Relation to Cell Activity and Its Application in Biomedical and Animal Husbandry Practices

As an innovative technology in biological applications, cold plasma is widely used in oral treatment, tissue regeneration, wound healing, and cancer therapy, etc., because of the adjustable composition and temperature which allow the plasma to react with bio-objects safely. Reactive oxygen species (ROS) produced by cold plasma regulate cell activity in an intensity- and time-dependent manner. A low level of ROS produced by cold plasma treatment within the appropriate intensities and times promotes proliferation of skin-related cells and increases angiogenesis, which aid in the acceleration of the wound healing process, while a high level of ROS produced by cold plasma treatment performed at a high intensity or over a long period of time inhibits the proliferation of endothelial cells, keratinocytes, fibroblasts, and cancer cells. Moreover, cold plasma can regulate stem cell proliferation by changing niche interface and producing nitric oxide directly. However, the molecular mechanism of cold plasma regulating cell activity and its potential application in the field of animal husbandry remain unclear in the literature. Therefore, this paper reviews the effects and possible regulatory mechanisms of cold plasma on the activities of endothelial cells, keratinocytes, fibroblasts, stem cells, and cancer cells to provide a theoretical basis for the application of cold plasma to skin-wound healing and cancer therapy. In addition, cold plasma exposure at a high intensity or an extended time shows excellent performances in killing various microorganisms existing in the environment or on the surface of animal food, and preparing inactivated vaccines, while cold plasma treatment within the appropriate conditions improves chicken growth and reproductive capacity. This paper introduces the potential applications of cold plasma treatment in relation to animal-breeding environments, animal health, their growth and reproduction, and animal food processing and preservation, which are all beneficial to the practice of animal husbandry and guarantee good animal food safety results.

The Role of Autophagy and Apoptosis in the Combined Action of Plasma-Treated Saline, Doxorubicin, and Medroxyprogesterone Acetate on K562 Myeloid Leukaemia Cells

The anti-cancer properties of plasma-treated solutions (PTS) and their interaction with drugs are one of the most popular topics in modern plasma medicine. Our research involved comparing the effects of four physiological saline solutions (0.9% NaCl, Ringer’s solution, Hank’s Balanced Salt Solution, Hank’s Balanced Salt Solution with amino acids added in concentrations observed in the human blood) treated with cold atmospheric plasma and studying the combined cytotoxic effect of PTS with doxorubicin and medroxyprogesterone acetate (MPA). Analysis of the effect of the studied agents on the formation of radicals in the incubation medium, the vitality of K562 myeloid leukaemia cells, and the processes of autophagy and apoptosis in them revealed two key findings. The first is that when using PTS and doxorubicin-containing PTS, autophagy is the predominant process in cancer cells. The second is that combining PTS with MPA enhances apoptotic processes. It was hypothesised that while autophagy is stimulated by the accumulation of reactive oxygen species in the cell, apoptosis is stimulated through specific cell progesterone receptors.

Modulation of the Tumor-Associated Immuno-Environment by Non-Invasive Physical Plasma

Over the past 15 years, investigating the efficacy of non-invasive physical plasma (NIPP) in cancer treatment as a safe oxidative stress inducer has become an active area of research. So far, most studies focused on the NIPP-induced apoptotic death of tumor cells. However, whether NIPP plays a role in the anti-tumor immune responses need to be deciphered in detail. In this review, we summarized the current knowledge of the potential effects of NIPP on immune cells, tumor-immune interactions, and the immunosuppressive tumor microenvironment. In general, relying on their inherent anti-oxidative defense systems, immune cells show a more resistant character than cancer cells in the NIPP-induced apoptosis, which is an important reason why NIPP is considered promising in cancer management. Moreover, NIPP treatment induces immunogenic cell death of cancer cells, leading to maturation of dendritic cells and activation of cytotoxic CD8⁺ T cells to further eliminate the cancer cells. Some studies also suggest that NIPP treatment may promote anti-tumor immune responses via other mechanisms such as inhibiting tumor angiogenesis and the desmoplasia of tumor stroma. Though more evidence is required, we expect a bright future for applying NIPP in clinical cancer management.

Cold Atmospheric Plasma Triggers Apoptosis via the Unfolded Protein Response in Melanoma Cells

Cold atmospheric plasma (CAP) describes a partially ionized gas carrying large amounts of reactive oxygen (ROS) and nitrogen species (RNS). Numerous studies reported strong antitumor activity of CAP, thus rendering it a promising approach for tumor therapy. Although several cellular mechanisms of its cytotoxicity were identified in recent years, the exact molecular effects and contributing signaling pathways are yet to be discovered. We discovered a strong activation of unfolded protein response (UPR) after CAP treatment with increased C/EBP homologous protein (CHOP) expression, which was mainly caused by protein misfolding and calcium loss in the endoplasmic reticulum. In addition, both ceramide level and ceramide metabolism were reduced after CAP treatment, which was then linked to the UPR activation. Pharmacological inhibition of ceramide metabolism resulted in sensitization of melanoma cells for CAP both in vitro and ex vivo. This study identified a novel mechanism of CAP-induced apoptosis in melanoma cells and thereby contributes to its potential application in tumor therapy.

Combination effect of cold atmospheric plasma with green synthesized zero-valent iron nanoparticles in the treatment of melanoma cancer model

Green synthesized zero-valent iron nanoparticles (nZVI) have high potential in cancer therapy. Cold atmospheric plasma (CAP) is also an emerging biomedical technique that has great potential to cure cancer. Therefore, the combined effect of CAP and nZVI might be promising in treatment of cancer. In this study, we evaluated the combined effect of CAP and nZVI on the metabolic activity of the surviving cells and induction of apoptosis in malignant melanoma in comparison with normal cells. Therefore, the effect of various time exposure of CAP radiation, different doses of nZVI, and the combined effect of CAP and nZVI were evaluated on the viability of malignant melanoma cells (B16-F10) and normal fibroblast cells (L929) at 24 h after treatment using MTT assay. Then, the effect of appropriate doses of each treatment on apoptosis was evaluated by fluorescence microscopy and flow cytometry with Annexin/PI staining. In addition, the expression of BAX, BCL2 and Caspase 3 (CASP3) was also assayed. The results showed although the combined effect of CAP and nZVI significantly showed cytotoxic effects and apoptotic activity on cancer cells, this treatment had no more effective compared to CAP or nZVI alone. In addition, evaluation of gene expression showed that combination therapy didn't improve expression of apoptotic genes in comparison with CAP or nZVI. In conclusion, combined treatment of CAP and nZVI does not seem to be able to improve the effect of monotherapy of CAP or nZVI. It may be due to the resistance of cancer cells to high ROS uptake or the accumulation of saturated ROS in cells, which prevents the intensification of apoptosis.

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.

Plasma oncology: Adjuvant therapy for head and neck cancer using cold atmospheric plasma

The worldwide incidence of head and neck cancer (HNC) exceeds half a million cases annually, and up to half of the patients with HNC present with advanced disease. Surgical resection remains the mainstay of treatment for many HNCs, although radiation therapy, chemotherapy, targeted therapy, and immunotherapy might contribute to individual patient’s treatment plan. Irrespective of which modality is chosen, disease prognosis remains suboptimal, especially for higher staging tumors. Cold atmospheric plasma (CAP) has recently demonstrated a substantial anti-tumor effect. After a thorough literature search, we provide a comprehensive review depicting the oncological potential of CAP in HNC treatment. We discovered that CAP applies to almost all categories of HNC, including upper aerodigestive tract cancers, head and neck glandular cancers and skin cancers. In addition, CAP is truly versatile, as it can be applied not only directly for superficial or luminal tumors but also indirectly for deep solid organ tumors. Most importantly, CAP can work collaboratively with existing clinical oncotherapies with synergistic effect. After our attempts to elaborate the conceivable molecular mechanism of CAP’s anti-neoplastic effect for HNC, we provide a brief synopsis of recent clinical and preclinical trials emphasizing CAP’s applicability in head and neck oncology. In conclusion, we have enunciated our vision of plasma oncology using CAP for near future HNC treatment.

Cold atmospheric pressure plasma treatment combined with starvation increases autophagy and apoptosis in melanoma in vitro and in vivo

Despite advances in therapy, malignant melanoma remains a fatal disease. Among several emerging approaches to combat cancer, cold atmospheric pressure plasma (CAP) has shown promising results as a novel antitumor agent in preclinical models so far. The technology mainly relies on the emittance of various reactive oxygen and nitrogen species (ROS/RNS) that are tumor-toxic at high concentrations. Moreover, malignant melanoma has a metabolic dimension that can be targeted by mild starvation. To this end, we investigated the combined effect of starvation and CAP treatment on melanoma in vitro and in vivo. In vitro, starvation+CAP led to cell morphology changes, decreased metabolic activity and increased lipid peroxidation accompanied by apoptosis and DNA fragmentation in murine B16 melanoma cells but not murine non-malignant L929 fibroblasts. This was paralleled by increased apoptosis (Bax, Bcl-2 and Caspase-3) and autophagy (Lc3 and Atg5)-related gene expression. In vivo, starvation reduced tumor burden. Combination with CAP treatment augmented this effect significantly, albeit there was no difference of combination treatment to CAP exposure alone. Interestingly, there was an overall greater increase of Lc3 and Atg5 in the tumor tissue compared to CAP exposure alone, while starvation-induced autophagy-related gene expression was similar to in the combination group. These data collectively suggest that CAP-derived ROS/RNS treatment and autophagy-induction augment antitumor effects in malignant melanoma in vitro and in vivo.

Cold Argon Athmospheric Plasma for Biomedicine: Biological Effects, Applications and Possibilities

Currently, plasma medicine is a synthetic direction that unites the efforts of specialists of various profiles. For the successful formation of plasma medicine, it is necessary to solve a large complex of problems, including creating equipment for generating cold plasma, revealing the biological effects of this effect, as well as identifying and justifying the most promising areas of its application. It is known that these biological effects include antibacterial and antiviral activity, the ability to stimulate hemocoagulation, pro-regenerative properties, etc. The possibility of using the factor in tissue engineering and implantology is also shown. Based on this, the purpose of this review was to form a unified understanding of the biological effects and biomedical applications of argon cold plasma. The review shows that cold plasma, like any other physical and chemical factors, has dose dependence, and the variable parameter in this case is the exposure of its application. One of the significant characteristics determining the specificity of the cold plasma effect is the carrier gas selection. This gas carrier is not just an ionized medium but modulates the response of biosystems to it. Finally, the perception of cold plasma by cellular structures can be carried out by activating a special molecular biosensor, the functioning of which significantly depends on the parameters of the medium (in the field of plasma generation and the cell itself). Further research in this area can open up new prospects for the effective use of cold plasma.

Inhibitory Effects of Cold Atmospheric Plasma on Inflammation and Tumor-Like Feature of Fibroblast-Like Synoviocytes from Patients with Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, debilitating systemic disease characterized by chronic inflammation and progressive joint destruction. Fibroblast-like synoviocytes (FLSs) are one of the most important players in the pathophysiology of RA, acting like tumor cells and secreting inflammatory cytokines. Previous research has shown that cold atmospheric plasma (CAP) inhibits cancer cells and may have anti-inflammatory properties. This study examined the effects of argon plasma jet-produced CAP on the suppression of invasion and inflammation caused by cultured RA-FLS. The findings revealed that CAP reduced cell viability and elevated the percentage of apoptotic RA-FLS by producing reactive oxygen species. Carboxyfluorescein diacetate succinimidyl ester (CFSE) staining confirmed that CAP could decrease the proliferation of RA-FLS. Furthermore, CAP effectively reduced the production of inflammatory factors (e.g., NF-κB and IL-6) as well as destructive factors like receptor activator of nuclear factor kappa-B ligand (RANKL) and matrix metalloproteinases-3 (MMP-3). These data suggest that CAP could be a promising treatment for slowing the progression of RA by reducing tumor-like features and inflammation in RA-FLS.

Biosafety and differentially expressed genes analysis of melanoma cells treated with cold atmospheric plasma

Cold atmospheric plasma (CAP) has attracted increasing attention due to its anti-bacterial and anti-tumor effects. Melanoma is an aggressive malignancy with increasing incidence rate and poor prognosis. Evaluating cell viability, apoptosis rate and reactive species injection efficiency of melanoma cells and human keratinocyte cells (HaCaT) treated with CAP to analyze biological safety of CAP. RNA-sequencing (RNA-seq) of A875 cells before and after treatment was performed to further explore the anti-tumor mechanism of CAP. CAP had a more significant biological effect on melanoma cells than HaCaT cells by inhibiting proliferation and promoting apoptosis. RNA-sequencing analysis showed that besides MAPK and p53 apoptotic signaling pathways, necroptosis and autophagy also played important roles in CAP-induced melanoma cells death. CAP can selectively kill melanoma cells and has good biosafety cytologically. Besides apoptosis, CAP can induce cell death via autophagy and necroptosis.

Cold Atmospheric Plasma-Activated Media Improve Paclitaxel Efficacy on Breast Cancer Cells in a Combined Treatment Model

Simple Summary

Breast cancer is the most commonly diagnosed cancer and the leading cause of cancer mortality in females, with chemotherapy currently the only adjunctive therapy. However, the disadvantages of chemotherapy are represented by toxicity/side effects, and for many women the benefit is uncertain. Cold atmospheric plasma in in vitro and in vivo experiments proved that it is able to selectively inhibit the growth of cancer cells in various cancer types, with less deleterious side effects. Current guidelines include paclitaxel as a chemotherapy of choice for various types of breast cancers. The aim of the study was to evaluate in vitro, on human breast cancer cell lines, a plasma-activated media as a cytotoxic agent and as an associative agent in a combined treatment for breast cancer with paclitaxel. The collected data indicated that the plasma-activated media amplified the cytotoxic effect of paclitaxel.

Abstract

The use of plasma-activated media (PAM), an alternative to direct delivery of cold atmospheric plasma to cancer cells, has recently gained interest in the plasma medicine field. Paclitaxel (PTX) is used as a chemotherapy of choice for various types of breast cancers, which is the leading cause of mortality in females due to cancer. In this study, we evaluated an alternative way to improve anti-cancerous efficiency of PTX by association with PAM, the ultimate achievement being a better outcome in killing tumoral cells at smaller doses of PTX. MCF-7 and MDA-MB-231 cell lines were used, and the outcome was measured by cell viability (MTT assay), the survival rate (clonogenic assay), apoptosis occurrence, and genotoxicity (COMET assay). Treatment consisted of the use of PAM in combination with under IC50 doses of PTX in short- and long-term models. The experimental data showed that PAM had the capacity to improve PTX’s cytotoxicity, as viability of the breast cancer cells dropped, an effect maintained in long-term experiments. A higher frequency of apoptotic, dead cells, and DNA fragmentation was registered in cells treated with the combined treatment as compared with those treated only with PT. Overall, PAM had the capacity to amplify the anti-cancerous effect of PTX.

When Onco-Immunotherapy Meets Cold Atmospheric Plasma: Implications on CAR-T Therapies

T cells engineered with chimeric antigen receptors (CAR) have demonstrated its widespread efficacy as a targeted immunotherapeutic modality. Yet, concerns on its specificity, efficacy and generalization prevented it from being established into a first-line approach against cancers. By reviewing challenges limiting its clinical application, ongoing efforts trying to resolve them, and opportunities that emerging oncotherapeutic modalities may bring to temper these challenges, we conclude that careful CAR design should be done to avoid the off-tumor effect, enhance the efficacy of solid tumor treatment, improve product comparability, and resolve problems such as differential efficacies of co-stimulatory molecules, cytokine storm, tumor lysis syndrome, myelosuppression and severe hepatotoxicity. As a promising solution, we propose potential synergies between CAR-T therapies and cold atmospheric plasma, an emerging onco-therapeutic strategy relying on reactive species, towards improved therapeutic efficacies and enhanced safety that deserve extensive investigations.

Oxidative Stress Differentially Influences the Survival and Metabolism of Cells in the Melanoma Microenvironment

The cellular composition of the tumor microenvironment, including tumor, immune, stromal, and endothelial cells, significantly influences responses to cancer therapies. In this study, we analyzed the impact of oxidative stress, induced by cold atmospheric plasma (CAP), on tumor cells, T cells, and macrophages, which comprise part of the melanoma microenvironment. To accomplish this, cells were grown in different in vitro cell culture models and were treated with varying amounts of CAP. Subsequent alterations in viability, proliferation, and phenotype were analyzed via flow cytometry and metabolic alterations by Seahorse Cell Mito Stress Tests. It was found that cells generally exhibited reduced viability and proliferation, stemming from CAP induced G2/M cell cycle arrest and subsequent apoptosis, as well as increased mitochondrial stress following CAP treatment. Overall, sensitivity to CAP treatment was found to be cell type dependent with T cells being the most affected. Interestingly, CAP influenced the polarization of M0 macrophages to a "M0/M2-like" phenotype, and M1 macrophages were found to display a heightened sensitivity to CAP induced mitochondrial stress. CAP also inhibited the growth and killed melanoma cells in 2D and 3D in vitro cell culture models in a dose-dependent manner. Improving our understanding of oxidative stress, mechanisms to manipulate it, and its implications for the tumor microenvironment may help in the discovery of new therapeutic targets.

Aberrant Expressional Profiling of Small RNA by Cold Atmospheric Plasma Treatment in Human Chronic Myeloid Leukemia Cells

Small RNAs (sRNAs), particularly microRNAs (miRNAs), are functional molecules that modulate mRNA transcripts and have been implicated in the etiology of various types of cancer. Cold atmospheric plasma (CAP) is a physical technology widely used in the field of cancer treatment after exhibiting extensive lethality on cancer cells. However, few studies have reported the exact role of miRNAs in CAP-induced anti-cancer effects. The aim of the present study was to determine whether miRNAs are involved in CAP-induced cytotoxicity by using high-throughput sequencing. Our research demonstrated that 28 miRNAs were significantly changed (17 upregulated and 11downregulated) following 24 h of treatment with a room-temperature argon plasma jet for 90 s compared with that of the untreated group in human chronic myeloid leukemia K562 cells. GO enrichment analysis revealed that these target genes were related to cell organelles, protein binding, and single-organism processes. Furthermore, KEGG pathway analysis demonstrated that the target genes of differentially expressed miRNAs were primarily involved in the cAMP signaling pathway, AMPK signaling pathway, and phosphatidylinositol signaling system. Taken together, our study demonstrated that CAP treatment could significantly alter the small RNA expression profile of chronic myeloid leukemia cells and provide a novel theoretical insight for elucidating the molecular mechanisms in CAP biomedicine application.

Cold Physical Plasma in Cancer Therapy: Mechanisms, Signaling, and Immunity

Despite recent advances in therapy, cancer still is a devastating and life-threatening disease, motivating novel research lines in oncology. Cold physical plasma, a partially ionized gas, is a new modality in cancer research. Physical plasma produces various physicochemical factors, primarily reactive oxygen and nitrogen species (ROS/RNS), causing cancer cell death when supplied at supraphysiological concentrations. This review outlines the biomedical consequences of plasma treatment in experimental cancer therapy, including cell death modalities. It also summarizes current knowledge on intracellular signaling pathways triggered by plasma treatment to induce cancer cell death. Besides the inactivation of tumor cells, an equally important aspect is the inflammatory context in which cell death occurs to suppress or promote the responses of immune cells. This is mainly governed by the release of damage-associated molecular patterns (DAMPs) to provoke immunogenic cancer cell death (ICD) that, in turn, activates cells of the innate immune system to promote adaptive antitumor immunity. The pivotal role of the immune system in cancer treatment, in general, is highlighted by many clinical trials and success stories on using checkpoint immunotherapy. Hence, the potential of plasma treatment to induce ICD in tumor cells to promote immunity targeting cancer lesions systemically is also discussed.

Lack of Adverse Effects of Cold Physical Plasma-Treated Blood from Leukemia Patients: A Proof-of-Concept Study

Chronic lymphocytic leukemia (CLL) is the most common blood malignancy with multiple therapeutic challenges. Cold physical plasma has been considered a promising approach in cancer therapy in recent years. In this study, we aimed to evaluate the cytotoxic effect of cold plasma or plasma-treated solutions (PTS) on hematologic parameters in the whole blood of CLL patients. The mean red blood cell count, white blood cell (WBC) count, platelet and hemoglobin counts, and peripheral blood smear images did not significantly differ between treated and untreated samples in either CLL or healthy individuals. However, both direct plasma and indirect PTS treatment increased lipid peroxidation and RNS deposition in the whole blood of CLL patients and in healthy subjects. In addition, the metabolic activity of WBCs was decreased with 120 s of cold plasma or PTS treatment after 24 h and 48 h. However, cold plasma and PTS treatment did not affect the prothrombin time, partial thromboplastin time, nor hemolysis in either CLL patients or in healthy individuals. The present study identifies the components of cold plasma to reach the blood without disturbing the basic parameters important in hematology, confirming the idea that the effect of cold plasma may not be limited to solid tumors and possibly extends to hematological disorders. Further cellular and molecular studies are needed to determine which cells in CLL patients are targeted by cold plasma or PTS.

Combined Effect of Cold Atmospheric Plasma and Curcumin in Melanoma Cancer

Curcumin (CUR) has interesting properties to cure cancer. Cold atmospheric plasma (CAP) is also an emerging biomedical technique that has great potential for cancer treatment. Therefore, the combined effect of CAP and CUR on inducing cytotoxicity and apoptosis of melanoma cancer cells might be promising. Here, we investigated the combined effects of CAP and CUR on cytotoxicity and apoptosis in B16-F10 melanoma cancer cells compared to L929 normal cells using MTT method, acridine orange/ethidium bromide fluorescence microscopic assay, and Annexin V/PI flow cytometry. In addition, the activation of apoptosis pathways was evaluated using BCL2, BAX, and Caspase-3 (CASP3) gene expression and ratio of BAX to BCL2 (BAX/BCL2). Finally, in silico study was performed to suggest the molecular mechanism of this combination therapy on melanoma cancer. Results showed that although combination therapy with CUR and CAP has cytotoxic and apoptotic effects on cancer cells, it did not improve apoptosis rate in melanoma B16-F10 cancer cells compared to monotherapy with CAP or CUR. In addition, evaluation of gene expression in cancer cell line confirmed that CUR and CAP concomitant treatment did not enhance the expression of apoptotic genes. In silico analysis of docked model suggested that CUR blocks aquaporin- (AQP-) 1 channel and prevents penetration of CAP-induced ROS into the cells. In conclusion, combination therapy with CAP and CUR does not improve the anticancer effect of each alone.

Simulation of Cold Atmospheric Plasma Generated by Floating-Electrode Dielectric Barrier Pulsed Discharge Used for the Cancer Cell Necrosis

A numerical simulation of a pulsed floating electrode dielectric barrier discharge (FE-DBD) at atmospheric pressure, used for melanoma cancer cell therapy, is performed using a plasma model in COMSOL Multiphysics software. Distributions of electron density, space charge, and electric field are presented at different instants of the pulsed argon discharge. Significant results related to the characteristics of the plasma device used, the inter-electrodes distance, and the power supply are obtained to improve the efficiency of FE-DBD apparatus for melanoma cancer cell treatment. The FE-DBD presents a higher sensitivity to short pulse durations, related to the accumulated charge over the dielectric barrier around the powered electrode. At higher applied voltage, more energy is injected into the discharge channel and an increase in electron density and electric consumed power is noted. Anticancer activity provided by the FE-DBD plasma is improved using a small interelectrode distance with a high electron emission coefficient and a high dielectric constant with a small dielectric thickness, allowing higher electron density, generating reactive species responsible for the apoptosis of tumor cells.

Effect of Cold Atmospheric Plasma on Epigenetic Changes, DNA Damage, and Possibilities for Its Use in Synergistic Cancer Therapy

Cold atmospheric plasma has great potential for use in modern medicine. It has been used in the clinical treatment of skin diseases and chronic wounds, and in laboratory settings it has shown effects on selective decrease in tumour-cell viability, reduced tumour mass in animal models and stem-cell proliferation. Many researchers are currently focusing on its application to internal structures and the use of plasma-activated liquids in tolerated and effective human treatment. There has also been analysis of plasma's beneficial synergy with standard pharmaceuticals to enhance their effect. Cold atmospheric plasma triggers various responses in tumour cells, and this can result in epigenetic changes in both DNA methylation levels and histone modification. The expression and activity of non-coding RNAs with their many important cell regulatory functions can also be altered by cold atmospheric plasma action. Finally, there is ongoing debate whether plasma-produced radicals can directly affect DNA damage in the nucleus or only initiate apoptosis or other forms of cell death. This article therefore summarises accepted knowledge of cold atmospheric plasma's influence on epigenetic changes, the expression and activity of non-coding RNAs, and DNA damage and its effect in synergistic treatment with routinely used pharmaceuticals.

In Vitro and In Vivo Enhancement of Temozolomide Effect in Human Glioblastoma by Non-Invasive Application of Cold Atmospheric Plasma

Glioblastoma (GBM) is one of the most aggressive forms of adult brain cancers and is highly resistant to treatment, with a median survival of 12-18 months after diagnosis. The poor survival is due to its infiltrative pattern of invasion into the normal brain parenchyma, the diffuse nature of its growth, and its ability to quickly grow, spread, and relapse. Temozolomide is a well-known FDA-approved alkylating chemotherapy agent used for the treatment of high-grade malignant gliomas, and it has been shown to improve overall survival. However, in most cases, the tumor relapses. In recent years, CAP has been used as an emerging technology for cancer therapy. The purpose of this study was to implement a combination therapy of CAP and TMZ to enhance the effect of TMZ and apparently sensitize GBMs. In vitro evaluations in TMZ-sensitive and resistant GBM cell lines established a CAP chemotherapy enhancement and potential sensitization effect across various ranges of CAP jet application. This was further supported with in vivo findings demonstrating that a single CAP jet applied non-invasively through the skull potentially sensitizes GBM to subsequent treatment with TMZ. Gene functional enrichment analysis further demonstrated that co-treatment with CAP and TMZ resulted in a downregulation of cell cycle pathway genes. These observations indicate that CAP can be potentially useful in sensitizing GBM to chemotherapy and for the treatment of glioblastoma as a non-invasive translational therapy.

Synergistic effect of cold atmospheric pressure plasma and free or liposomal doxorubicin on melanoma cells

The aim of the present study was to investigate combined effects of cold atmospheric plasma (CAP) and the chemotherapeutic drug doxorubicin (DOX) on murine and human melanoma cells, and normal cells. In addition to free drug, the combination of CAP with a liposomal drug (DOX-LIP) was also studied for the first time. Thiazolyl blue tetrazolium bromide (MTT) and Trypan Blue exclusion assays were used to evaluate cell viability; the mechanism of cell death was evaluated by flow cytometry. Combined treatment effects on the clonogenic capability of melanoma cells, was also tested with soft agar colony formation assay. Furthermore the effect of CAP on the cellular uptake of DOX or DOX-LIP was examined. Results showed a strong synergistic effect of CAP and DOX or DOX-LIP on selectively decreasing cell viability of melanoma cells. CAP accelerated the apoptotic effect of DOX (or DOX-LIP) and dramatically reduced the aggressiveness of melanoma cells, as the combination treatment significantly decreased their anchorage independent growth. Moreover, CAP did not result in increased cellular uptake of DOX under the present experimental conditions. In conclusion, CAP facilitates DOX cytotoxic effects on melanoma cells, and affects their metastatic potential by reducing their clonogenicity, as shown for the first time.

Transferred Cold Atmospheric Plasma Treatment on Melanoma Skin Cancer Cells with/without Catalase Enzyme In Vitro

Cold atmospheric plasma (CAP) is a promising tool to overcome certain cancerous and precancerous conditions in dermatology. A scheme of transferred CAP was first developed to treat melanoma (B16F10) skin cancer cells as well as non-malignant (L929) cells in vitro. CAP was transferred using a silicone tube with a jet system that was developed and was assessed as to whether it could generate reactive oxygen and nitrogen species (RONS) at near-room temperature. The transferred CAP was characterized electrically and spectroscopically. Biological data showed that the transferred CAP killed cancer cells but not non-malignant (L929) cells. Plasma treatment was effective with a time duration of 30 s, whereas non-malignant (L929) cells were less damaged during plasma treatment. In addition, catalase (CAT) enzyme was applied to neutralize and detoxify the RONS generated by the transferred CAP. These findings suggest that transferred CAP can be considered a melanoma cancer therapy.

Antitumor Effects in Gas Plasma-Treated Patient-Derived Microtissues—An Adjuvant Therapy for Ulcerating Breast Cancer?

Despite global research and continuous improvement in therapy, cancer remains a challenging disease globally, substantiating the need for new treatment avenues. Medical gas plasma technology has emerged as a promising approach in oncology in the last years. Several investigations have provided evidence of an antitumor action in vitro and in vivo, including our recent work on plasma-mediated reduction of breast cancer in mice. However, studies of gas plasma exposure on patient-derived tumors with their distinct microenvironment (TME) are scarce. To this end, we here investigated patient-derived breast cancer tissue after gas plasma-treated ex vivo. The tissues were disjoint to pieces smaller than 100 µm, embedded in collagen, and incubated for several days. The viability of the breast cancer tissue clusters and their outgrowth into their gel microenvironment declined with plasma treatment. This was associated with caspase 3-dependent apoptotic cell death, paralleled by an increased expression of the anti-metastatic adhesion molecule epithelial (E)-cadherin. Multiplex chemokine/cytokine analysis revealed a marked decline in the release of the interleukins 6 and 8 (IL-6, IL-8) and monocyte-chemoattractant-protein 1 (MCP) known to promote a cancer-promoting milieu in the TME. In summary, we provide here, for the first time, evidence of a beneficial activity of gas plasma exposure on human patient-derived breast cancer tissue.

Gas Plasma Technology Augments Ovalbumin Immunogenicity and OT-II T Cell Activation Conferring Tumor Protection in Mice

Reactive oxygen species (ROS/RNS) are produced during inflammation and elicit protein modifications, but the immunological consequences are largely unknown. Gas plasma technology capable of generating an unmatched variety of ROS/RNS is deployed to mimic inflammation and study the significance of ROS/RNS modifications using the model protein chicken ovalbumin (Ova vs oxOva). Dynamic light scattering and circular dichroism spectroscopy reveal structural modifications in oxOva compared to Ova. T cells from Ova-specific OT-II but not from C57BL/6 or SKH-1 wild type mice presents enhanced activation after Ova addition. OxOva exacerbates this activation when administered ex vivo or in vivo, along with an increased interferon-gamma production, a known anti-melanoma agent. OxOva vaccination of wild type mice followed by inoculation of syngeneic B16F10 Ova-expressing melanoma cells shows enhanced T cell number and activation, decreased tumor burden, and elevated numbers of antigen-presenting cells when compared to their Ova-vaccinated counterparts. Analysis of oxOva using mass spectrometry identifies three hot spots regions rich in oxidative modifications that are associated with the increased T cell activation. Using Ova as a model protein, the findings suggest an immunomodulating role of multi-ROS/RNS modifications that may spur novel research lines in inflammation research and for vaccination strategies in oncology.

Acidified Nitrite Contributes to the Antitumor Effect of Cold Atmospheric Plasma on Melanoma Cells

Cold atmospheric plasma (CAP) is partially ionized gas near room temperature with previously reported antitumor effects. Despite extensive research and growing interest in this technology, active components and molecular mechanisms of CAP are not fully understood to date. We used Raman spectroscopy and colorimetric assays to determine elevated nitrite and nitrate levels after treatment with a MiniFlatPlaster CAP device. Previously, we demonstrated CAP-induced acidification. Cellular effects of nitrite and strong extracellular acidification were assessed using live-cell imaging of intracellular Ca²⁺ levels, cell viability analysis as well as quantification of p21 and DNA damage. We further characterized these observations by analyzing established molecular effects of CAP treatment. A synergistic effect of nitrite and acidification was found, leading to strong cytotoxicity in melanoma cells. Interestingly, protein nitration and membrane damage were absent after treatment with acidified nitrite, thereby challenging their contribution to CAP-induced cytotoxicity. Further, phosphorylation of ERK1/2 was increased after treatment with both acidified nitrite and indirect CAP. This study characterizes the impact of acidified nitrite on melanoma cells and supports the importance of RNS during CAP treatment. Further, it defines and evaluates important molecular mechanisms that are involved in the cancer cell response to CAP.

Intracellular Responses Triggered by Cold Atmospheric Plasma and Plasma-Activated Media in Cancer Cells

Cold atmospheric plasma (CAP), an ionized gas operating at room temperature, has been increasingly studied with respect to its potential use in medicine, where its beneficial effects on tumor reduction in oncology have been demonstrated. This review discusses the cellular changes appearing in cell membranes, cytoplasm, various organelles, and DNA content upon cells’ direct or indirect exposure to CAP or CAP-activated media/solutions (PAM), respectively. In addition, the CAP/PAM impact on the main cellular processes of proliferation, migration, protein degradation and various forms of cell death is addressed, especially in light of CAP use in the oncology field of plasma medicine.

Low-Temperature Argon Plasma Regulates Skin Moisturizing and Melanogenesis-Regulating Markers through Yes-Associated Protein

Extensive water loss and melanin hyperproduction can cause various skin disorders. Low-temperature argon plasma (LTAP) has shown the possibility of being used for the treatment of various skin diseases, such as atopic dermatitis and skin cancer. However, the role of LTAP in regulating skin moisturizing and melanogenesis has not been investigated. In this study, we aimed to determine the effect of LTAP on yes-associated protein (YAP), a major transcriptional coactivator in the Hippo signaling pathway that is involved in skin moisturizing and melanogenesis-regulating markers. In normal human epidermal keratinocytes (NHEKs), the human epidermal keratinocyte line HaCaT, and human dermal fibroblasts (HDFs), we found that LTAP exhibited increased expression levels of YAP protein. In addition, the expression levels of filaggrin (FLG), which is involved in natural moisturizing factors (NMFs), and hyaluronic acid synthase (HAS), transglutaminase (TGM), and involucrin (IVL), which regulate skin barrier and moisturizing, were also increased after exposure to LTAP. Furthermore, collagen type I alpha 1 and type III alpha 1 (COL1A1, COL3A1) were increased after LTAP exposure, but the expression level of matrix metalloproteinase-3 (MMP-3) was reduced. Moreover, LTAP was found to suppress alpha-melanocyte stimulating hormone (α-MSH)-induced melanogenesis in murine melanoma B16F10 cells and normal human melanocytes (NHEMs). LTAP regulates melanogenesis of the melanocytes through decreased YAP pathway activation in a melanocortin 1 receptor (MC1R)-dependent manner. Taken together, our data show that LTAP regulates skin moisturizing and melanogenesis through modulation of the YAP pathway, and the effect of LTAP on the expression level of YAP varies from cell to cell. Thus, LTAP might be developed as a treatment method to improve the skin barrier, moisture content, and wrinkle formation, and to reduce melanin generation.

The Feasibility Study of Plasma-activated Water as a Physical Therapy to Induce Apoptosis in Melanoma Cancer Cells In-vitro

Low-temperature plasma (LTP) has demonstrated great potential in biomedicine, especially in cancer therapy in-vivo and in-vitro. Plasma activated water (PAW) as an indirect plasma therapy is a significant source of reactive oxygen and nitrogen species (RONS) which play an important role in apoptosis induction in cancer cells. In this study, Helium (He) plasma jet operating in 0.75 W and 20 kHz as dissipated power and frequency, respectively, is used as the cold plasma source. The electrical, thermal, and spectroscopic properties of (He) plasma jet and pH as well as the conductivity and temperature of PAW samples, are investigated. The concentration of hydrogen peroxide (H2O2), nitrite (NO2 -) and nitrate (NO- 3), which are produced in water as long-lived anticancer RONS, was measured 471.6, 7.9 and 93.5 μM, respectively after 6 min of plasma treatment. Alamar Blue and flow cytometry assays were employed to investigate the B16F10 cancer metabolic activity and apoptosis. These data support that cold atmospheric plasma (CAP) can produce a certain concentration of anti-cancer agents in water and induce apoptosis in melanoma cancer cells due to RONSs via activating the caspase 3 pathway.

Plasma Treatment Limits Human Melanoma Spheroid Growth and Metastasis Independent of the Ambient Gas Composition

Simple Summary

Despite recent advances in therapeutic options, melanoma remains a deadly disease with a poor prognosis. Physical gas plasma has been proposed as a promising technology for the treatment of melanoma. This study aimed to develop and investigate a convenient test system based on three-dimensional cell cultures (spheroids) of two melanoma cell lines in response to physical gas plasma. The experimental approach combined high-content imaging technology and different gas plasma treatment modalities (direct and indirect, gas compositions). Our results revealed that plasma treatment was toxic for both cell lines predominantly dependent on the treatment time. Furthermore, we addressed the question of safety and morphological changes in response to physical gas plasma exposure and found no support for metastatic progression. Treatment with physical gas plasma effectively limited the growth of human 3D melanoma spheroids and provided a versatile test system for more in vivo-like tumor tissue.

Abstract

Melanoma skin cancer is still a deadly disease despite recent advances in therapy. Previous studies have suggested medical plasma technology as a promising modality for melanoma treatment. However, the efficacy of plasmas operated under different ambient air conditions and the comparison of direct and indirect plasma treatments are mostly unexplored for this tumor entity. Moreover, exactly how plasma treatment affects melanoma metastasis has still not been explained. Using 3D tumor spheroid models and high-content imaging technology, we addressed these questions by utilizing one metastatic and one non-metastatic human melanoma cell line targeted with an argon plasma jet. Plasma treatment was toxic in both cell lines. Modulating the oxygen and nitrogen ambient air composition (100/0, 75/25, 50/50, 25/75, and 0/100) gave similar toxicity and reduced the spheroid growth for all conditions. This was the case for both direct and indirect treatments, with the former showing a treatment time-dependent response while the latter resulted in cytotoxicity with the longest treatment time investigated. Live-cell imaging of in-gel cultured spheroids indicated that plasma treatment did not enhance metastasis, and flow cytometry showed a significant modulation of S100A4 but not in any of the five other metastasis-related markers (β-catenin, E-cadherin, LEF1, SLUG, and ZEB1) investigated.