Effect of Plasma-Activated Lactated Ringer's Solution on Pancreatic Cancer Cells In Vitro and In Vivo

Cold atmospheric plasma-activated medium for potential ovarian cancer therapy

Cold atmospheric plasma (CAP) has emerged as an innovative tool with broad medical applications, including ovarian cancer (OC) treatment. By bringing CAP in close proximity to liquids such as water or cell culture media, solutions containing reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated, called plasma-activated media (PAM). In this systematic review, we conduct an in-depth analysis of studies focusing on PAM interactions with biological substrates. We elucidate the diverse mechanisms involved in the activation of different media and the complex network of chemical reactions underlying the generation and consumption of the prominent reactive species. Furthermore, we highlight the promises of PAM in advancing biomedical applications, such as its stability for extended periods under appropriate storage conditions. We also examine the application of PAM as an anti-cancer and anti-metastatic treatment for OC, with a particular emphasis on its ability to induce apoptosis via distinct signaling pathways, inhibit cell growth, suppress cell motility, and enhance the therapeutic effects of chemotherapy. Finally, the future outlook of PAM therapy in biomedical applications is speculated, with emphasis on the safety issues relevant to clinical translation.

Chemotherapy Assessment in Advanced Multicellular 3D Models of Pancreatic Cancer: Unravelling the Importance of Spatiotemporal Mimicry of the Tumor Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is a challenge for global health with very low survival rate and high therapeutic resistance. Hence, advanced preclinical models for treatment screening are of paramount importance. Herein, chemotherapeutic (gemcitabine) assessment on novel (polyurethane) scaffold-based spatially advanced 3D multicellular PDAC models is carried out. Through comprehensive image-based analysis at the protein level, and expression analysis at the mRNA level, the importance of stromal cells is confirmed, primarily activated stellate cells in the chemoresistance of PDAC cells within the models. Furthermore, it is demonstrated that, in addition to the presence of activated stellate cells, the spatial architecture of the scaffolds, i.e., segregation/compartmentalization of the cancer and stromal zones, affect the cellular evolution and is necessary for the development of chemoresistance. These results highlight that, further to multicellularity, mapping the tumor structure/architecture and zonal complexity in 3D cancer models is important for better mimicry of the in vivo therapeutic response.

Combined Application of Cold Physical Plasma and Chemotherapeutics against Chondrosarcoma Cells

Chondrosarcoma (CS) is a rare malignant bone sarcoma that primarily affects cartilage cells in the femur and pelvis. While most subtypes exhibit slow growth with a very good prognosis, some aggressive subtypes have a poorer overall survival. CS is known for its resistance to chemotherapy and radiotherapy, leaving surgery as the sole effective therapeutic option. Cold physical plasma (CPP) has been explored in vitro as a potential therapy, demonstrating positive anti-tumor effects on CS cells. This study investigated the synergistic effects of combining CPP with cytostatics on CS cells. The chemotherapeutic agents cisplatin, doxorubicin, and vincristine were applied to two CS cell lines (CAL-78 and SW1353). After determining their IC20 and IC50, they were combined with CPP in both cell lines to assess their impact on the cell proliferation, viability, metabolism, and apoptosis. This combined approach significantly reduced the cell proliferation and viability while increasing the apoptosis signals compared to cytostatic therapy alone. The combination of CPP and chemotherapeutic drugs shows promise in targeting chemoresistant CS cells, potentially improving the prognosis for patients in clinical settings.

Selective adhesion inhibition and hyaluronan envelope reduction of dermal tumor cells by cold plasma-activated medium

The sensitivity to cold plasma is specific to tumor cells while leaving normal tissue cells unaffected. This is the desired challenge in cancer therapy. Therefore, the focus of this work was a comparative study concerning the plasma sensitivity of dermal tumor cells (A-431) versus non-tumorigenic dermal cells (HaCaT) regarding their adhesion capacity. We found a selective inhibiting effect of plasma-activated medium on the adhesion of tumor cells while hardly affecting normal cells. We attributed this to a lower basal gene expression for the adhesion-relevant components CD44, hyaluronan synthase 2 (HAS2), HAS3, and the hyaluronidases in A431. Noteworthy, after plasma exposure, we revealed a significantly higher expression and synthesis of the hyaluronan envelope, the HAS3 gene, and the transmembrane adhesion receptors in non-tumorigenic HaCaTs.

Anticancer Effects of Plasma-Treated Water Solutions from Clinically Approved Infusion Liquids Supplemented with Organic Molecules

Water solutions treated by cold atmospheric plasmas (CAPs) currently stand out in the field of cancer treatment as sources of exogenous blends of reactive oxygen and nitrogen species (RONS). It is well known that the balance of RONS inside both eukaryotic and prokaryotic cells is directly involved in physiological as well as pathological pathways. Also, organic molecules including phenols could exert promising anticancer effects, mostly attributed to their pro-oxidant ability in vitro and in vivo to generate RONS like O2-, H2O2, and a mixture of potentially cytotoxic compounds. By our vision of combining the efficacy of plasma-produced RONS and the use of organic molecules, we could synergistically attack cancer cells; yet, so far, this combination, to the best of our knowledge, has been completely unexplored. In this study, l-tyrosine, an amino acid with a phenolic side chain, is added to a physiological solution, often used in clinical practice (SIII) to be exposed to plasma. The efficacy of the gas plasma-oxidized SIII solution, containing tyrosine, was evaluated on four cancer cell lines selected from among tumors with poor prognosis (SHSY-5Y, MCF-7, HT-29, and SW-480). The aim was to induce tumor toxicity and trigger apoptosis pathways. The results clearly indicate that the plasma-treated water solution (PTWS) reduced cell viability and oxygen uptake due to an increase in intracellular ROS levels and activation of apoptosis pathways in all investigated cancer cells, which may be related to the activation of the mitochondrial-mediated and p-JNK/caspase-3 signaling pathways. This research offers improved knowledge about the physiological mechanisms underlying cancer treatment and a valid method to set up a prompt, adequate, and effective cancer treatment in the clinic.

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 plasma and inhibition of STAT3 selectively target tumorigenicity in osteosarcoma

Osteosarcoma (OS) is a malignant type of bone cancer that arises in periods of increased bone formation. Curative strategies for these types of tumors have remained essentially unchanged for decades and the overall survival for most advanced cases is still dismally low. This is in part due to the existence of drug resistant Cancer Stem Cells (CSC) with progenitor properties that are responsible for tumor relapse and metastasis. In the quest for therapeutic alternatives for OS, Cold Atmospheric Plasmas and Plasma-Treated Liquids (PTL) have come to the limelight as a source of Reactive Oxygen and Nitrogen Species displaying selectivity towards a variety of cancer cell lines. However, their effects on CSC subpopulations and in vivo tumor growth have been barely studied to date. By employing bioengineered 3D tumor models and in vivo assays, here we show that low doses of PTL increase the levels of pro-stemness factors and the self-renewal ability of OS cells, coupled to an enhanced in vivo tumor growth potential. This could have critical implications to the field. By proposing a combined treatment, our results demonstrate that the deleterious pro-stemness signals mediated by PTL can be abrogated when this is combined with the STAT3 inhibitor S3I-201, resulting in a strong suppression of in vivo tumor growth. Overall, our study unveils an undesirable stem cell-promoting function of PTL in cancer and supports the use of combinatorial strategies with STAT3 inhibitors as an efficient treatment for OS avoiding critical side effects. We anticipate our work to be a starting point for wider studies using relevant 3D tumor models to evaluate the effects of plasma-based therapies on tumor subpopulations of different cancer types. Furthermore, combination with STAT3 inhibition or other suitable cancer type-specific targets can be relevant to consolidate the development of the field.

Enhancing the Impact of Chemotherapy on Ewing Sarcoma Cells through Combination with Cold Physical Plasma

Although Ewing's sarcoma (ES) is a rare, but very aggressive tumor disease affecting the musculoskeletal system, especially in children, it is very aggressive and difficult to treat. Although medical advances and the establishment of chemotherapy represent a turning point in the treatment of ES, resistance to chemotherapy, and its side effects, continue to be problems. New treatment methods such as the application of cold physical plasma (CPP) are considered potential supporting tools since CPP is an exogenous source of reactive oxygen and nitrogen species, which have similar mechanisms of action in the tumor cells as chemotherapy. This study aims to investigate the synergistic effects of CPP and commonly used cytostatic chemotherapeutics on ES cells. The chemotherapy drugs doxorubicin and vincristine, the most commonly used in the treatment of ES, were applied to two different ES cell lines (RD-ES and A673) and their IC₂₀ and IC₅₀ were determined. In addition, individual chemotherapeutics in combination with CPP were applied to the ES cells and the effects on cell growth, cell viability, and apoptosis processes were examined. A single CPP treatment resulted in the dose-dependent growth inhibition of ES cells. The combination of different cytostatics and CPP led to significant growth inhibition, a reduction in cell viability, and higher rates of apoptosis compared to cells not additionally exposed to CPP. The combination of CPP treatment and the application of cytostatic drugs to ES cells showed promising results, significantly enhancing the cytotoxic effects of chemotherapeutic agents. These preclinical in vitro data indicate that the use of CPP can enhance the efficacy of common cytostatic chemotherapeutics, and thus support the translation of CPP as an anti-tumor therapy in clinical routine.

Current understanding of Plasma-activated solutions for potential cancer therapy

Cancer therapy consists of multidisciplinary treatment combining surgery, chemotherapy, radiotherapy, and immunotherapy. Despite the elucidation of cancer mechanisms by comprehensive genomic and epigenomic analyses and the development of molecular therapy, drug resistance and severe side effects have presented challenges to the long-awaited development of new therapies. With the rapid technological advances in the last decade, there are now reports concerning potential applications of non-equilibrium atmospheric pressure plasma (NEAPP) in cancer therapy. Two approaches have been tried: direct irradiation with NEAPP (direct plasma) and the administration of a liquid (e.g., culture medium, saline, Ringer's lactate) activated by NEAPP (plasma-activated solutions: PAS). Direct plasma is a unique treatment method in which various active species, charged ions, and photons are delivered to the affected area, but the direct plasma approach has physical limitations related to the device used, such as a limited depth of reach and limited irradiation area. PAS is a liquid that contains reactive oxygen species generated by PAS, and it has been confirmed to have antitumor activity that functions in the same manner as direct plasma. This review introduces recent studies of PAS and informs researchers about the potential of PAS for cancer therapy.Key Policy HighlightsPotential applications of plasma-activated solutions (PAS) in cancer therapy are described.Plasma-activated species generated in PAS, its effect on tumor cells, contribution to non-malignant immune cells, selectivity and safety are presented.The proposed anti-tumor mechanisms of PAS to date are described.Efficacy and safety evaluations of PAS have been studied in experimental animal models, but no human studies have been conducted.

Use of Cold Atmospheric Plasma in the Treatment of Squamous Cell Carcinoma: in vitro Effects and Clinical Application in Feline Tumors: A Pilot Study

Cold atmospheric plasma (CAP) has shown promising results against squamous cell carcinoma (SCC) in both in vivo and in vitro assays, mainly in humans and mice. Its applicability for treatment of feline tumors, however, remains unknown. This study aimed to evaluate the anticancer effects of CAP on a head and neck squamous cell carcinoma (HNSCC) cell lineage and against a clinical case of cutaneous SCC in a cat. Control and treatment groups employing the HNSCC cell line (SCC-25) were used, the latter exposed to CAP for 60 seconds, 90 seconds, or 120 seconds. The cells were subjected to the MTT assay nitric oxidation assay and thermographic in vitro analyses. The clinical application was performed in one cat with cutaneous SCC (3 sites). The lesions were treated and evaluated by thermographic, histopathological, and immunohistochemical examinations (caspase-3 and TNF-alpha). Treatment of the SCC-25 cells for 90 seconds and 120 seconds resulted in a significant nitrite concentration increase. Decreased cell viability was observed after 24 hours and 48 hours, regardless of exposure time. However, the cell viability reduction observed at 72 hours was significant only in the 120 seconds treatment. In vitro, the temperature decreased for all treatment times, while the plasma induced a slight increase in mean temperature (0.7°C) in the in vivo assay. Two of the 3 clinical tumors responded to the treatment: one with a complete response and the other, partial, while the third (lower lip SCC) remained stable. Both remaining tumors displayed apoptotic areas and increased expression of caspase-3 and TNF-alpha. Adverse effects were mild and limited to erythema and crusting. The CAP exhibited an in vitro anticancer effect on the HNSCC cell line, demonstrated by a dose-dependent cell viability reduction. In vivo, the therapy appears safe and effective against feline cutaneous SCC. The treatment did not result in a clinical response for 1 of 3 lesions (proliferative lower lip tumor), however, a biological effect was still demonstrated by the higher expression of apoptosis indicators.

Plasma activated Ringer's lactate solution

Low-temperature plasma (LTP) has been widely used in life science. Plasma-activated solutions were defined as solutions irradiated with LTP, and water, medium, and Ringer's solutions have been irradiated with LTP to produce plasma-activated solutions. They contain chemical compounds produced by reactions among LTP, air, and solutions. Reactive oxygen and nitrogen species (RONS) are major components in plasma-activated solutions and recent studies revealed that plasma-activated organic compounds are produced in plasma-activated Ringer's lactate solution (PAL). Many in vitro and in vivo studies demonstrated that PAL exhibits anti-tumor effects on cancers, and biochemical analyses revealed intracellular molecular mechanisms of cancer cell death by PAL.

Exploring the Use of Cold Atmospheric Plasma to Overcome Drug Resistance in Cancer

Drug resistance is a major problem in cancer treatment, as it limits the effectiveness of pharmacological agents and can lead to disease progression. Cold atmospheric plasma (CAP) is a technology that uses ionized gas (plasma) to generate reactive oxygen and nitrogen species (RONS) that can kill cancer cells. CAP is a novel approach for overcoming drug resistance in cancer. In recent years, there has been a growing interest in using CAP to enhance the effectiveness of chemotherapy drugs. In this review, we discuss the mechanisms behind this phenomenon and explore its potential applications in cancer treatment. Going through the existing literature on CAP and drug resistance in cancer, we highlight the challenges and opportunities for further research in this field. Our review suggests that CAP could be a promising option for overcoming drug resistance in cancer and warrants further investigation.

Cold atmospheric plasma enhances doxorubicin selectivity in metastasic bone cancer

High-dose systemic chemotherapy constitutes a main strategy in the management of bone metastases, employing drugs like doxorubicin (DOX), related with severe side effects. To solve this issue, Cold Atmospheric Plasmas (CAP) have been proposed as potential non-invasive anti-cancer agents capable of improving the efficacy of traditional drugs. Here, we investigate the cytotoxic effects of Plasma Conditioned Medium (PCM) in combination with DOX in prostate cancer cells from bone metastases (PC-3) as well as in non-malignant bone-cells. PCM was able to enhance the cytotoxic potential of DOX both in monolayer and in a 3D bioengineered model mimicking the bone matrix. The combined treatment of PCM + DOX resulted in a profound downregulation of the redox defenses (CAT1, SOD2, GPX1) and drug resistance genes (MRP1, MDR1, BCRP1), resulting in an enhanced uptake of DOX coupled to an overload of intracellular ROS. Besides, PCM improved the cytotoxic potential of DOX interfering on the migratory and clonogenic potential of PC-3 cells. Importantly, non-malignant bone cells were unaffected by the combination of PCM + DOX. Overall, these new findings may represent a new therapeutic approach for the management of bone metastatic prostate cancer in the future.

Conductive Gas Plasma Treatment Augments Tumor Toxicity of Ringer's Lactate Solutions in a Model of Peritoneal Carcinomatosis

Reactive species generated by medical gas plasma technology can be enriched in liquids for use in oncology targeting disseminated malignancies, such as metastatic colorectal cancer. Notwithstanding, reactive species quantities depend on the treatment mode, and we recently showed gas plasma exposure in conductive modes to be superior for cancer tissue treatment. However, evidence is lacking that such a conductive mode also equips gas plasma-treated liquids to confer augmented intraperitoneal anticancer activity. To this end, employing atmospheric pressure argon plasma jet kINPen-treated Ringer's lactate (oxRilac) in a CT26-model of colorectal peritoneal carcinomatosis, we tested repeated intraabdominal injection of such remotely or conductively oxidized liquid for antitumor control and immunomodulation. Enhanced reactive species formation in conductive mode correlated with reduced tumor burden in vivo, emphasizing the advantage of conduction over the free mode for plasma-conditioned liquids. Interestingly, the infiltration of lymphocytes into the tumors was equally enhanced by both treatments. However, significantly lower levels of interleukin (IL)4 and IL13 and increased levels of IL2 argue for a shift in intratumoral T-helper cell subpopulations correlating with disease control. In conclusion, our data argue for using conductively over remotely prepared plasma-treated liquids for anticancer treatment.

Thermosensitive hydrogels to deliver reactive species generated by cold atmospheric plasma: a case study with methylcellulose

Hydrogels have been recently proposed as suitable materials to generate reactive oxygen and nitrogen species (RONS) upon gas-plasma treatment, and postulated as promising alternatives to conventional cancer therapies. Acting as delivery vehicles that allow a controlled release of RONS to the diseased site, plasma-treated hydrogels can overcome some of the limitations presented by plasma-treated liquids in in vivo therapies. In this work, we optimized the composition of a methylcellulose (MC) hydrogel to confer it with the ability to form a gel at physiological temperatures while remaining in the liquid phase at room temperature to allow gas-plasma treatment with suitable formation of plasma-generated RONS. MC hydrogels demonstrated the capacity for generation, prolonged storage and release of RONS. This release induced cytotoxic effects on the osteosarcoma cancer cell line MG-63, reducing its cell viability in a dose-response manner. These promising results postulate plasma-treated thermosensitive hydrogels as good candidates to provide local anticancer therapies.

In Vivo Metabolic Analysis of the Anticancer Effects of Plasma-Activated Saline in Three Tumor Animal Models

In recent years, the emerging technology of cold atmospheric pressure plasma (CAP) has grown rapidly along with the many medical applications of cold plasma (e.g., cancer, skin disease, tissue repair, etc.). Plasma-activated liquids (e.g., culture media, water, or normal saline, previously exposed to plasma) are being studied as cancer treatments, and due to their advantages, many researchers prefer plasma-activated liquids as an alternative to CAP in the treatment of cancer. In this study, we showed that plasma-activated-saline (PAS) treatment significantly inhibited tumor growth, as compared with saline, in melanoma, and a low-pH environment had little effect on tumor growth in vivo. In addition, based on an ultra-high-performance liquid tandem chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) analysis of tumor cell metabolism, the glycerophospholipid metabolic pathway was the most susceptible metabolic pathway to PAS treatment in melanoma in vitro and in vivo. Furthermore, PAS also inhibited cell proliferation in vivo in oral tongue squamous-cell cancer and non-small-cell lung cancer. There were few toxic side effects in the three animal models, and the treatment was deemed safe to use. In the future, plasma-activated liquids may serve as a potential therapeutic approach in the treatment of cancer.

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.

[Molecular Mechanisms Underlying Cellular Responses to the Loading of Non-thermal Atmospheric Pressure Plasma-activated Solutions]

Plasma medicine is a rapidly expanding new field of interdisciplinary research that combines physics, chemistry, biology, and medicine. Non-thermal atmospheric pressure plasma (NTAPP) has recently been applied to living cells and tissues, and has emerged as a novel technology for medical applications, such as wound healing, blood coagulation, and cancer treatment. NTAPP was found to affect cells indirectly through the treatment of cells with previously prepared medium irradiated by NTAPP, termed plasma-activated medium (PAM). The treatment of culture media with NTAPP results in the generation of a large amount of reactive oxygen species and reactive nitrogen species, and their derived species. We found that PAM triggered a spiral apoptotic cascade in the mitochondrial-nuclear network in A549 cancer cells. This process induced the depletion of total cellular NAD⁺ and elevations in intracellular calcium ion, ultimately leading to cell death. We also detected the production of hydroxyl radical and elevations in intracellular ferrous ions in PAM-treated cells. The elevations observed in ferrous ions may have been due to their release from the intracellular iron store, ferritin. However, difficulties are associated with applying PAM to the clinical phase because culture media cannot be used for medical treatments. The anti-tumor activity of plasma-activated Ringer's solution was significantly stronger than that of PAM. At the end, we herein demonstrated the advantages of the combined application of plasma-activated acetate Ringer's solution and hyperthermia, a heat treatment at 42℃, for A549 cancer cell death and elucidated the underlying mechanisms.

Low temperature plasma irradiation products of sodium lactate solution that induce cell death on U251SP glioblastoma cells were identified

Low-temperature plasma is being widely used in the various fields of life science, such as medicine and agriculture. Plasma-activated solutions have been proposed as potential cancer therapeutic reagents. We previously reported that plasma-activated Ringer’s lactate solution exhibited selective cancer-killing effects, and that the plasma-treated L-sodium lactate in the solution was an anti-tumor factor; however, the components that are generated through the interactions between plasma and L-sodium lactate and the components responsible for the selective killing of cancer cells remain unidentified. In this study, we quantified several major chemical products, such as pyruvate, formate, and acetate, in plasma-activated L-sodium lactate solution by nuclear magnetic resonance analysis. We further identified novel chemical products, such as glyoxylate and 2,3-dimethyltartrate, in the solution by direct infusion-electrospray ionization with tandem mass spectrometry analysis. We found that 2,3-dimethyltartrate exhibited cytotoxic effects in glioblastoma cells, but not in normal astrocytes. These findings shed light on the identities of the components that are responsible for the selective cytotoxic effect of plasma-activated solutions on cancer cells, and provide useful data for the potential development of cancer treatments using plasma-activated L-sodium lactate solution.

Selectivity of direct plasma treatment and plasma-conditioned media in bone cancer cell lines

Atmospheric pressure plasma jets have been shown to impact several cancer cell lines, both in vitro and in vivo. These effects are based on the biochemistry of the reactive oxygen and nitrogen species generated by plasmas in physiological liquids, referred to as plasma-conditioned liquids. Plasma-conditioned media are efficient in the generation of reactive species, inducing selective cancer cell death. However, the concentration of reactive species generated by plasma in the cell culture media of different cell types can be highly variable, complicating the ability to draw precise conclusions due to the differential sensitivity of different cells to reactive species. Here, we compared the effects of direct and indirect plasma treatment on non-malignant bone cells (hOBs and hMSCs) and bone cancer cells (SaOs-2s and MG63s) by treating the cells directly or exposing them to previously treated cell culture medium. Biological effects were correlated with the concentrations of reactive species generated in the liquid. A linear increase in reactive species in the cell culture medium was observed with increased plasma treatment time independent of the volume treated. Values up to 700 µM for H2O2 and 140 µM of NO2- were attained in 2 mL after 15 min of plasma treatment in AdvDMEM cell culture media. Selectivity towards bone cancer cells was observed after both direct and indirect plasma treatments, leading to a decrease in bone cancer cell viability at 72 h to 30% for the longest plasma treatment times while maintaining the survival of non-malignant cells. Therefore, plasma-conditioned media may represent the basis for a potentially novel non-invasive technique for bone cancer therapy.

Murine Macrophages Modulate Their Inflammatory Profile in Response to Gas Plasma-Inactivated Pancreatic Cancer Cells

Macrophages and immuno-modulation play a dominant role in the pathology of pancreatic cancer. Gas plasma is a technology recently suggested to demonstrate anticancer efficacy. To this end, two murine cell lines were employed to analyze the inflammatory consequences of plasma-treated pancreatic cancer cells (PDA) on macrophages using the kINPen plasma jet. Plasma treatment decreased the metabolic activity, viability, and migratory activity in an ROS- and treatment time-dependent manner in PDA cells in vitro. These results were confirmed in pancreatic tumors grown on chicken embryos in the TUM-CAM model (in ovo). PDA cells promote tumor-supporting M2 macrophage polarization and cluster formation. Plasma treatment of PDA cells abrogated this cluster formation with a mixed M1/M2 phenotype observed in such co-cultured macrophages. Multiplex chemokine and cytokine quantification showed a marked decrease of the neutrophil chemoattractant CXCL1, IL6, and the tumor growth supporting TGFβ and VEGF in plasma-treated compared to untreated co-culture settings. At the same time, macrophage-attractant CCL4 and MCP1 release were profoundly enhanced. These cellular and secretome data suggest that the plasma-inactivated PDA6606 cells modulate the inflammatory profile of murine RAW 264.7 macrophages favorably, which may support plasma 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.

Plasma-Treated Solutions (PTS) in Cancer Therapy

Simple Summary

Cold physical plasma is a partially ionized gas generating various reactive oxygen and nitrogen species (ROS/RNS) simultaneously. ROS/RNS have therapeutic effects when applied to cells and tissues either directly from the plasma or via exposure to solutions that have been treated beforehand using plasma processes. This review addresses the challenges and opportunities of plasma-treated solutions (PTSs) for cancer treatment.

Abstract

Cold physical plasma is a partially ionized gas generating various reactive oxygen and nitrogen species (ROS/RNS) simultaneously. ROS/RNS have therapeutic effects when applied to cells and tissues either directly from the plasma or via exposure to solutions that have been treated beforehand using plasma processes. This review addresses the challenges and opportunities of plasma-treated solutions (PTSs) for cancer treatment. These PTSs include plasma-treated cell culture media in experimental research as well as clinically approved solutions such as saline and Ringer’s lactate, which, in principle, already qualify for testing in therapeutic settings. Several types of cancers were found to succumb to the toxic action of PTSs, suggesting a broad mechanism of action based on the tumor-toxic activity of ROS/RNS stored in these solutions. Moreover, it is indicated that the PTS has immuno-stimulatory properties. Two different routes of application are currently envisaged in the clinical setting. One is direct injection into the bulk tumor, and the other is lavage in patients suffering from peritoneal carcinomatosis adjuvant to standard chemotherapy. While many promising results have been achieved so far, several obstacles, such as the standardized generation of large volumes of sterile PTS, remain to be addressed.

Preclinical Verification of the Efficacy and Safety of Aqueous Plasma for Ovarian Cancer Therapy

Simple Summary

Ovarian cancer is among the most malignant gynecologic cancers, in part because intraperitoneal recurrence occurs with high frequency due to occult metastasis. We have demonstrated a metastasis-inhibitory effect of plasma-activated medium (PAM) in ovarian cancer cells. Here, we investigated whether PAM inhibits intraperitoneal metastasis. We observed that PAM induced macrophages’ infiltration into the disseminated lesion, which was co-localized with inducible nitric oxide synthase (iNOS)-positive signal, indicating that PAM might induce M1-type macrophages. We also observed that intraperitoneal washing with plasma-activated lactate Ringer’s solution (PAL) significantly improved the overall survival rate in an ovarian cancer mouse model. Intraperitoneal washing therapy might be effective to improve clinical outcomes of ovarian cancer.

Abstract

Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy. The major cause of EOC’s lethality is that intraperitoneal recurrence occurs with high frequency due to occult metastasis. We had demonstrated that plasma-activated medium (PAM) exerts a metastasis-inhibitory effect on ovarian cancer in vitro and in vivo. Here we investigated how PAM inhibits intraperitoneal metastasis. We studied PAM’s inhibition of micro-dissemination onto the omentum by performing in vivo imaging in combination with a sequential histological analysis. The results revealed that PAM induced macrophage infiltration into the disseminated lesion. The iNOS-positive signal was co-localized at the macrophages in the existing lesion, indicating that PAM might induce M1-type macrophages. This may be another mechanism of the antitumor effect through a PAM-evoked immune response. Intraperitoneal lavage with plasma-activated lactate Ringer’s solution (PAL) significantly improved the overall survival rate in an ovarian cancer mouse model. Our results demonstrated the efficiency and practicality of aqueous plasma for clinical applications.

Osteosarcoma tissue-engineered model challenges oxidative stress therapy revealing promoted cancer stem cell properties

The use of oxidative stress generated by Cold Atmospheric Plasma (CAP) in oncology is being recently studied as a novel potential anti-cancer therapy. However, the beneficial effects of CAP for treating osteosarcoma have mostly been demonstrated in 2-dimensional cultures of cells, which do not mimic the complexity of the 3-dimensional (3D) bone microenvironment. In order to evaluate the effects of CAP in a relevant context of the human disease, we developed a 3D tissue-engineered model of osteosarcoma using a bone-like scaffold made of collagen type I and hydroxyapatite nanoparticles. Human osteosarcoma cells cultured within the scaffold showed a high capacity to infiltrate and proliferate and to exhibit osteomimicry in vitro. As expected, we observed significantly different functional behaviors between monolayer and 3D cultures when treated with Cold Plasma-Activated Ringer's Solution (PAR). Our data reveal that the 3D environment not only protects cells from PAR-induced lethality by scavenging and diminishing the amount of reactive oxygen and nitrogen species generated by CAP, but also favours the stemness phenotype of osteosarcoma cells. This is the first study that demonstrates the negative effect of PAR on cancer stem-like cell subpopulations in a 3D biomimetic model of cancer. These findings will allow to suitably re-focus research on plasma-based therapies in future.

Role of Short- and Long-Lived Reactive Species on the Selectivity and Anti-Cancer Action of Plasma Treatment In Vitro

Simple Summary

One fundamental feature that has emerged from in vitro application of cold plasmas in cancer treatment is the key role of the liquid phase covering the cells. In the present work, we investigated the effect of direct and indirect plasma treatments on two cancer and three normal cell lines to assess the benefits of one treatment over the other in terms of death of tumor versus healthy cells. Our results demonstrate that indirect plasma treatment is as efficient at killing tumor cells as an appropriate combination of H₂O₂, NO₂⁻ and acidic pH in ad hoc solutions, while sparing normal cells. However, direct plasma treatment is far more efficient at killing normal than tumor cells, and we provide evidence that short- and long-lived reactive species contribute synergistically to kill normal cells, while having an additive effect regarding tumor cell death. Collectively, our results call the use of plasma-activated liquid in cancer treatment into question.

Abstract

(1) Plasma-activated liquids (PAL) have been extensively studied for their anti-cancer properties. Two treatment modalities can be applied to the cells, direct and indirect plasma treatments, which differ by the environment to which the cells are exposed. For direct plasma treatment, the cells covered by a liquid are present during the plasma treatment time (phase I, plasma ON) and the incubation time (phase II, plasma OFF), while for indirect plasma treatment, phase I is cell-free and cells are only exposed to PAL during phase II. The scope of this work was to study these two treatment modalities to bring new insights into the potential use of PAL for cancer treatment. (2) We used two models of head and neck cancer cells, CAL27 and FaDu, and three models of normal cells (1Br3, NHK, and RPE-hTERT). PBS was used as the liquid of interest, and the concentration of plasma-induced H₂O₂, NO₂⁻ and NO₃⁻, as well as pH change, were measured. Cells were exposed to direct plasma treatment, indirect plasma treatment or reconstituted buffer (PBS adjusted with plasma-induced concentrations of H₂O₂, NO₂⁻, NO₃⁻ and pH). Metabolic cell activity, cell viability, lipid peroxidation, intracellular ROS production and caspase 3/7 induction were quantified. (3) If we showed that direct plasma treatment is slightly more efficient than indirect plasma treatment and reconstituted buffer at inducing lipid peroxidation, intracellular increase of ROS and cancer cell death in tumor cells, our data also revealed that reconstituted buffer is equivalent to indirect plasma treatment. In contrast, normal cells are quite insensitive to these two last treatment modalities. However, they are extremely sensitive to direct plasma treatment. Indeed, we found that phase I and phase II act in synergy to trigger cell death in normal cells and are additive concerning tumor cell death. Our data also highlight the presence in plasma-treated PBS of yet unidentified short-lived reactive species that contribute to cell death. (4) In this study, we provide strong evidence that, in vitro, the concentration of RONS (H₂O₂, NO₂⁻ and NO₃⁻) in combination with the acidic pH are the main drivers of plasma-induced PBS toxicity in tumor cells but not in normal cells, which makes ad hoc reconstituted solutions powerful anti-tumor treatments. In marked contrast, direct plasma treatment is deleterious for normal cells in vitro and should be avoided. Based on our results, we discuss the limitations to the use of PAL for cancer treatments.

Plasma-Conditioned Liquids as Anticancer Therapies In Vivo: Current State and Future Directions

Plasma-conditioned liquids (PCL) are gaining increasing attention in the medical field, especially in oncology, and translation to the clinics is advancing on a good path. This emerging technology involving cold plasmas has great potential as a therapeutic approach in cancer diseases, as PCL have been shown to selectively kill cancer cells by triggering apoptotic mechanisms without damaging healthy cells. In this context, PCL can be injected near the tumor or intratumorally, thereby allowing the treatment of malignant tumors located in internal organs that are not accessible for direct cold atmospheric plasma (CAP) treatment. Therefore, PCL constitutes a very interesting and minimally invasive alternative to direct CAP treatment in cancer therapy, avoiding surgeries and allowing multiple local administrations. As the field advances, it is progressively moving to the evaluation of the therapeutic effects of PCL in in vivo scenarios. Exciting developments are pushing forward the clinical translation of this novel therapy. However, there is still room for research, as the quantification and identification of reactive oxygen and nitrogen species (RONS) in in vivo conditions is not yet clarified, dosage regimens are highly variable among studies, and other more relevant in vivo models could be used. In this context, this work aims to present a critical review of the state of the field of PCL as anticancer agents applied in in vivo studies.

Ability of plasma-activated acetated Ringer's solution to induce A549 cell injury is enhanced by a pre-treatment with histone deacetylase inhibitors

Non-thermal plasma (NTP) is applicable to living cells and has emerged as a novel technology for cancer therapy. NTP affect cells not only by direct irradiation, but also by an indirect treatment with previously prepared plasma-activated liquid. Histone deacetylase (HDAC) inhibitors have the potential to enhance susceptibility to anticancer drugs and radiation because these reagents decondense the compact chromatin structure by neutralizing the positive charge of the histone tail. The aim of the present study was to demonstrate the advantage of the combined application of plasma-activated acetated Ringer’s solution (PAA) and HDAC inhibitors on A549 cancer cells. PAA maintained its ability for at least 1 week stored at any temperature tested. Cell death was enhanced more by combined regimens of PAA and HDAC inhibitors, such as trichostatin A (TSA) and valproic acid (VPA), than by a single PAA treatment and was accompanied by ROS production, DNA breaks, and mitochondria dysfunction through a caspase-independent pathway. These phenomena induced the depletion of ATP and elevations in intracellular calcium concentrations. The sensitivities of HaCaT cells as normal cells to PAA were less than that of A549 cells. These results suggest that HDAC inhibitors synergistically induce the sensitivity of cancer cells to PAA.

Comprehensive biomedical applications of low temperature plasmas

The main component of plasma medicine is the use of low-temperature plasma (LTP) as a powerful tool for biomedical applications. LTP generates high reactivity at low temperatures and can be activated with noble gases with molecular mixtures or compressed air. LTP reactive species are quickly produced, and are a remarkably good source of reactive oxygen and nitrogen species including singlet oxygen (O₂), ozone (O₃), hydroxyl radicals (OH), nitrous oxide (NO), and nitrogen dioxide (NO₂). Its low gas temperature and highly reactive non-equilibrium chemistry make it appropriate for the alteration of inorganic surfaces and delicate biological systems. Treatment of oral biofilm-related infections, treatment of wounds and skin diseases, assistance in cancer treatment, treatment of viruses' infections (e.g. herpes simplex), and optimization of implants surfaces are included among the extensive plasma medicine applications. Each of these applications will be discussed in this review article.

Hyperthermia synergistically enhances cancer cell death by plasma-activated acetated Ringer's solution

Applications of non-thermal plasma (NTP) discharges in medicine, particularly cancer therapy, have increased in recent years. The aim of the present study was to investigate the advantages of the combined application of NTP-irradiated acetated Ringer's solution (PAA) and hyperthermia, a heat treatment at 42 °C, on A549 cancer cell death and elucidate the underlying mechanisms. Cell death was enhanced more by the above combined treatment and was accompanied by increases in intracellular calcium ([Ca²⁺]i). The activation of transient receptor potential melastatin 2 (TRPM2) may enhance cell death because the addition of TRPM2 inhibitors and knockdown of TRPM2 significantly abrogated the above phenomena. TRPM2 is a temperature-sensitive, Ca²⁺-permeable, non-elective cation channel and hydrogen peroxide (H₂O₂) and ADP ribose are its main agonists. PAA functioned as a donor of reactive oxygen species, mainly H₂O₂, and a treatment with PAA under hyperthermia induced both mitochondrial and nuclear damage with DNA breaks. The activation of poly(ADP-ribose) polymerase-1 as the DNA repair mechanism induced TRPM2 activation because this enzyme accumulates ADP ribose. The sensitivity of fibroblasts as normal cells to PAA was less than that of A549 cells. These results suggest that hyperthermia synergistically induces the sensitivity of cancer cells to PAA.

Cancer treatment with gas plasma and with gas plasma-activated liquid: positives, potentials and problems of clinical translation

Gas plasmas, created in atmospheric pressure conditions, both thermal (hot) and non-thermal (cold) are emerging as useful tools in medicine. During surgery, hot gas plasmas are useful to reduce thermal damage and seal blood vessels. Gas plasma pens use cold gas plasma to produce reactive chemical species with selective action against cancers, which can be readily exposed in surgery or treated from outside of the body. Solutions activated by cold gas plasma have potential as a novel treatment modality for treatment of less readily accessible tumours, or those with high metastatic potential. This review summarises the preclinical and clinical trial evidence currently available, as well as the challenges for translation of direct gas plasma and gas plasma-activated solution treatment into regular practice.

The Hyaluronan Pericellular Coat and Cold Atmospheric Plasma Treatment of Cells

In different tumors, high amounts of hyaluronan (HA) are correlated with tumor progression. Therefore, new tumor therapy strategies are targeting HA production and degradation. In plasma medicine research, antiproliferative and apoptosis-inducing effects on tumor cells were observed using cold atmospheric plasma (CAP) or plasma-activated media (PAM). Until now, the influence of PAM on the HA pericellular coat has not been the focus of research. PAM was generated by argon-plasma treatment of Dulbecco’s modified Eagle’s Medium via the kINPen®09 plasma jet. The HA expression on PAM-treated HaCaT cells was determined by flow cytometry and confocal laser scanning microscopy. Changes in the adhesion behavior of vital cells in PAM were observed by impedance measurement using the xCELLigence system. We found that PAM treatment impaired the HA pericellular coat of HaCaT cells. The time-dependent adhesion was impressively diminished. However, a disturbed HA coat alone was not the reason for the inhibition of cell adhesion because cells enzymatically treated with HAdase did not lose their adhesion capacity completely. Here, we showed for the first time that the plasma-activated medium (PAM) was able to influence the HA pericellular coat.

Quantitative Investigation into the influence of intravenous fluids on human immune and cancer cell lines

The effect of intravenous fluids (IVF) has been investigated clinically through the assessment of post-treatment reactions. However, the responses to IVF vary from patient-to-patient. It is important to understand the response of IVF treatment to be able to provide optimal IVF care. Herein, we investigated the impact of commonly used IVFs, Dextrose, NaCl and Ringer on different human cancer (HepG2 (liver hepatocellular carcinoma) and MCF7 (breast adenocarcinoma)) and immune cell lines (U937 (lymphoma) monocyte and macrophages). The effect of IVF exposure on single cells was characterized using hemocytometer, fluorescence microscopy and flow cytometry. Quantitative data on the viability and morphology of the cells were obtained. Our results emphasize that different IVFs demonstrate important differences in how they influence distinct cell lines. Particularly, we observed that the lactated ringer and dextrose solutions altered the viability and nuclear size of cancer and immune cells differently. Our findings present valuable information to the knowledge of cellular-level IVF effects for further investigations in IVF usage on diverse patient populations and support the importance and necessity of developing optimal diluents not only for drug stability but also for patient benefits.

Non-thermal plasma-activated lactate solution kills U251SP glioblastoma cells in an innate reductive manner with altered metabolism

Ringer's lactate solution irradiated by non-thermal plasma, comprised of radicals, electrons, and ions, is defined as plasma-activated lactate (PAL). PAL exhibited antitumor effects in glioblastoma U251SP cells, which we termed PAL-specific regulated cell death. In contrast to the oxidative stress condition typical of cells incubated in plasma-activated medium (PAM), U251SP cells treated with Ringer's lactate solution or PAL exhibited changes in intracellular metabolites that were reductive in the redox state, as measured by the ratio of oxidative/reductive glutathione concentrations. In the metabolomic profiles of PAL-treated cells, the generation of acetyl-CoA increased for lipid metabolism from alanine and asparagine. PAL thus induces regulated death of U251SP glioblastoma cells in more innate microenvironments than PAM.

A Novel Scaffold-Based Hybrid Multicellular Model for Pancreatic Ductal Adenocarcinoma-Toward a Better Mimicry of the in vivo Tumor Microenvironment

With a very low survival rate, pancreatic ductal adenocarcinoma (PDAC) is a deadly disease. This has been primarily attributed to (i) its late diagnosis and (ii) its high resistance to current treatment methods. The latter specifically requires the development of robust, realistic in vitro models of PDAC, capable of accurately mimicking the in vivo tumor niche. Advancements in the field of tissue engineering (TE) have helped the development of such models for PDAC. Herein, we report for the first time a novel hybrid, polyurethane (PU) scaffold-based, long-term, multicellular (tri-culture) model of pancreatic cancer involving cancer cells, endothelial cells, and stellate cells. Recognizing the importance of ECM proteins for optimal growth of different cell types, the model consists of two different zones/compartments: an inner tumor compartment consisting of cancer cells [fibronectin (FN)-coated] and a surrounding stromal compartment consisting of stellate and endothelial cells [collagen I (COL)-coated]. Our developed novel hybrid, tri-culture model supports the proliferation of all different cell types for 35 days (5 weeks), which is the longest reported timeframe in vitro. Furthermore, the hybrid model showed extensive COL production by the cells, mimicking desmoplasia, one of PDAC's hallmark features. Fibril alignment of the stellate cells was observed, which attested to their activated state. All three cell types expressed various cell-specific markers within the scaffolds, throughout the culture period and showed cellular migration between the two zones of the hybrid scaffold. Our novel model has great potential as a low-cost tool for in vitro studies of PDAC, as well as for treatment screening.

Cold Atmospheric Plasma: A Powerful Tool for Modern Medicine

Cold atmospheric plasma use in clinical studies is mainly limited to the treatment of chronic wounds, but its application in a wide range of medical fields is now the goal of many analyses. It is therefore likely that its application spectrum will be expanded in the future. Cold atmospheric plasma has been shown to reduce microbial load without any known significant negative effects on healthy tissues, and this should enhance its possible application to any microbial infection site. It has also been shown to have anti-tumour effects. In addition, it acts proliferatively on stem cells and other cultivated cells, and the highly increased nitric oxide levels have a very important effect on this proliferation. Cold atmospheric plasma use may also have a beneficial effect on immunotherapy in cancer patients. Finally, it is possible that the use of plasma devices will not remain limited to surface structures, because current endeavours to develop sufficiently miniature microplasma devices could very likely lead to its application in subcutaneous and internal structures. This study summarises the available literature on cold plasma action mechanisms and analyses of its current in vivo and in vitro use, primarily in the fields of regenerative and dental medicine and oncology.

Stope M. Gas Plasma-Treated Prostate Cancer Cells Augment Myeloid Cell Activity and Cytotoxicity

Despite recent improvements in cancer treatment, with many of them being related to foster antitumor immunity, tumor-related deaths continue to be high. Novel avenues are needed to complement existing therapeutic strategies in oncology. Medical gas plasma technology recently gained attention due to its antitumor activity. Gas plasmas act via the local deposition of a plethora of reactive oxygen species (ROS) that promote the oxidative cancer cell death. The immunological consequences of plasma-mediated tumor cell death are only poorly understood, however. To this end, we exposed two prostate cancer cell lines (LNCaP, PC3) to gas plasma in vitro, and investigated the immunomodulatory effects of the supernatants in as well as of direct co-culturing with two human myeloid cell lines (THP-1, HL-60). After identifying the cytotoxic action of the kINPen plasma jet, the supernatants of plasma-treated prostate cancer cells modulated myeloid cell-related mitochondrial ROS production and their metabolic activity, proliferation, surface marker expression, and cytokine release. Direct co-culture amplified differentiation-like surface marker expression in myeloid cells and promoted their antitumor-toxicity in the gas plasma over the untreated control conditions. The results suggest that gas plasma-derived ROS not only promote prostate cancer cell death but also augment myeloid cell activity and cytotoxicity.

Plasma-activated Ringer's Lactate Solution Displays a Selective Cytotoxic Effect on Ovarian Cancer Cells

Epithelial Ovarian Cancer (EOC) is one of the leading causes of cancer-related deaths among women and is characterized by the diffusion of nodules or plaques from the ovary to the peritoneal surfaces. Conventional therapeutic options cannot eradicate the disease and show low efficacy against resistant tumor subclones. The treatment of liquids via cold atmospheric pressure plasma enables the production of plasma-activated liquids (PALs) containing reactive oxygen and nitrogen species (RONS) with selective anticancer activity. Thus, the delivery of RONS to cancer tissues by intraperitoneal washing with PALs might be an innovative strategy for the treatment of EOC. In this work, plasma-activated Ringer’s Lactate solution (PA-RL) was produced by exposing a liquid substrate to a multiwire plasma source. Subsequently, PA-RL dilutions are used for the treatment of EOC, non-cancer and fibroblast cell lines, revealing a selectivity of PA-RL, which induces a significantly higher cytotoxic effect in EOC with respect to non-cancer cells.

Plasma-activated medium promotes autophagic cell death along with alteration of the mTOR pathway

The biological function of non-thermal atmospheric pressure plasma has been widely accepted in several types of cancer. We previously developed plasma-activated medium (PAM) for clinical use, and demonstrated that PAM exhibits a metastasis-inhibitory effect on ovarian cancer through reduced MMP-9 secretion. However, the anti-tumor effects of PAM on endometrial cancer remain unknown. In this study, we investigated the inhibitory effect of PAM on endometrial cancer cell viability in vitro. Our results demonstrated that AMEC and HEC50 cell viabilities were reduced by PAM at a certain PAM ratio, and PAM treatment effectively increased autophagic cell death in a concentration dependent manner. In addition, we evaluated the molecular mechanism of PAM activity and found that the mTOR pathway was inactivated by PAM. Moreover, our results demonstrated that the autophagy inhibitor MHY1485 partially inhibited the autophagic cell death induced by PAM treatment. These findings indicate that PAM decreases the viability of endometrial cancer cells along with alteration of the mTOR pathway, which is critical for cancer cell viability. Collectively, our data suggest that PAM inhibits cell viability while inducing autophagic cell death in endometrial cancer cells, representing a potential novel treatment for endometrial cancer.

Scalable Treatment of Flowing Organic Liquids Using Ambient-Air Glow Discharge for Agricultural Applications

In this work, we developed a portable device with low production and operation costs for generating ambient-air glow discharge (AAGD) that is transferred to the surface of flowing liquid and demonstrated its applicability to practical use in agriculture. An experiment procedure that ensured the stable treatment of various liquids was established. Additionally, it was found that humidity did not have a significant effect on the treatment process, which makes the use of the developed device possible in various locations. It was found that an L-phenylalanine solution treated with AAGD allows simultaneous 40% hydroponic radish-sprout growth promotion with a bactericidal effect. Further, scalability and practical-application possibilities in hydroponic plant growth were discussed.

Gas Plasma-Conditioned Ringer's Lactate Enhances the Cytotoxic Activity of Cisplatin and Gemcitabine in Pancreatic Cancer In Vitro and In Ovo

Pancreatic cancer is one of the most aggressive tumor entities. Diffuse metastatic infiltration of vessels and the peritoneum restricts curative surgery. Standard chemotherapy protocols include the cytostatic drug gemcitabine with limited efficacy at considerable toxicity. In search of a more effective and less toxic treatment modality, we tested in human pancreatic cancer cells (MiaPaca and PaTuS) a novel combination therapy consisting of cytostatic drugs (gemcitabine or cisplatin) and gas plasma-conditioned Ringer’s lactate that acts via reactive oxygen species. A decrease in metabolic activity and viability, change in morphology, and cell cycle arrest was observed in vitro. The combination treatment was found to be additively toxic. The findings were validated utilizing an in ovo tumor model of solid pancreatic tumors growing on the chorion-allantois membrane of fertilized chicken eggs (TUM-CAM). The combination of the drugs (especially cisplatin) with the plasma-conditioned liquid significantly enhanced the anti-cancer effects, resulting in the induction of cell death, cell cycle arrest, and inhibition of cell growth with both of the cell lines tested. In conclusion, our novel combination approach may be a promising new avenue to increase the tolerability and efficacy of locally applied chemotherapeutic in diffuse metastatic peritoneal carcinomatosis of the pancreas.

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.

Risk Assessment of kINPen Plasma Treatment of Four Human Pancreatic Cancer Cell Lines with Respect to Metastasis

Cold physical plasma has limited tumor growth in many preclinical models and is, therefore, suggested as a putative therapeutic option against cancer. Yet, studies investigating the cells' metastatic behavior following plasma treatment are scarce, although being of prime importance to evaluate the safety of this technology. Therefore, we investigated four human pancreatic cancer cell lines for their metastatic behavior in vitro and in chicken embryos (in ovo). Pancreatic cancer was chosen as it is particularly metastatic to the peritoneum and systemically, which is most predictive for outcome. In vitro, treatment with the kINPen plasma jet reduced pancreatic cancer cell activity and viability, along with unchanged or decreased motility. Additionally, the expression of adhesion markers relevant for metastasis was down-regulated, except for increased CD49d. Analysis of 3D tumor spheroid outgrowth showed a lack of plasma-spurred metastatic behavior. Finally, analysis of tumor tissue grown on chicken embryos validated the absence of an increase of metabolically active cells physically or chemically detached with plasma treatment. We conclude that plasma treatment is a safe and promising therapeutic option and that it does not promote metastatic behavior in pancreatic cancer cells in vitro and in ovo.

Elucidation of in vitro cellular steps induced by antitumor treatment with plasma-activated medium

Numerous studies have reported cold atmospheric plasma cytotoxic activities in various cancer cell lines, either by direct exposure to non-thermal plasma or indirectly by activating a medium (plasma-activated medium, PAM) prior to cell treatment. We suggested the use of in vitro 3D tumor model spheroids to determine the potential of PAM for cancer therapy at the tissue scale, especially in human tumor tissue. This work aimed to better understand the effect of PAM on human colorectal tumor spheroids by describing the in vitro-induced-cell death kinetics and associated mechanisms to further improve its therapeutic potential. Tumor spheroid growth was delayed depending on contact time with PAM. Medium osmolarity was increased by activation with low temperature Helium plasma jet but it did not fully explain the observed growth delay. PAM impaired tumor cell viability through intracellular ATP depletion, leading within hours to both cell apoptosis and necrosis as well as mitochondrial oxidative stress. When successive treatments were spaced over time, cumulative effects on the growth delay of spheroids were observed. Taken together, these results demonstrated that plasma-activated liquids may represent a novel and efficient therapeutic method for the treatment of tumors, especially when successive treatments are applied.