Reaction Chemistry Generated by Nanosecond Pulsed Dielectric Barrier Discharge Treatment is Responsible for the Tumor Eradication in the B16 Melanoma Mouse Model

Peroxiredoxin 1 modulates oxidative stress resistance and cell apoptosis through stemness in liver cancer under non-thermal plasma treatment

The role of peroxiredoxin 1 (PRDX1), a crucial enzyme that reduces reactive oxygen and nitrogen species levels in HepG2 human hepatocellular carcinoma (HCC) cells, in the regulation of HCC cell stemness under oxidative stress and the underlying mechanisms remain largely unexplored. Here, we investigated the therapeutic potential of non-thermal plasma in targeting cancer stem cells (CSCs) in HCC, focusing on the mechanisms of resistance to oxidative stress and the role of PRDX1. By simulating oxidative stress conditions using the plasma-activated medium, we found that a reduction in PRDX1 levels resulted in a considerable increase in HepG2 cell apoptosis, suggesting that PRDX1 plays a key role in oxidative stress defense mechanisms in CSCs. Furthermore, we found that HepG2 cells had higher spheroid formation capability and increased levels of stem cell markers (CD133, c-Myc, and OCT-4), indicating strong stemness. Interestingly, PRDX1 expression was notably higher in HepG2 cells than in other HCC cell types such as Hep3B and Huh7 cells, whereas the expression levels of other PRDX family proteins (PRDX 2-6) were relatively consistent. The inhibition of PRDX1 expression and peroxidase activity by conoidin A resulted in markedly reduced stemness traits and increased cell death rate. Furthermore, in a xenograft mouse model, PRDX1 downregulation considerably inhibited the formation of solid tumors after plasma-activated medium (PAM) treatment. These findings underscore the critical role of PRDX 1 in regulating stemness and apoptosis in HCC cells under oxidative stress, highlighting PRDX1 as a promising therapeutic target for NTP-based treatment in HCC.

Microscopic mechanistic study of the penetration distributions for plasma reactive oxygen and nitrogen species based on sialic acid targeting on the cell membrane surface

The ability of cold atmospheric plasmas (CAPs) to produce a wide range of active constituents while maintaining a low or even room temperature of the gas has made it a novel research area of great interest. During plasma action, cancer cell membrane surface components are susceptible to oxidative modification by reactive oxygen and nitrogen species (RONS). In this study, the process of oxidative modification of membrane surface components sialic acid by RONS was investigated based on molecular dynamics simulations, and the penetration mechanism of long-lived particles ONOOH and its homolytic products at the membrane-water interface and the effect of appropriate electric field action were studied. The results showed that cancer cells with high sialic acid expression were less stable than healthy cells. Plasma treatment may promote the ONOOH homolysis process, and its homolysis product OH free radical is more likely to adsorb near sialic acid molecules by hydrogen bonding, resulting in oxidative modification. The interaction force between OH free radical and sialic acid molecules is stronger than ONOOH, which helps to further understand the oxidative modification reaction in membrane environment. At the same time, appropriate electric field stimulation can enhance the depth of penetration of RONS to more effectively treat the pathological state of biological tissues. The study proposes the use of membrane surface sialic acid as a cancer therapeutic target and provides guidance for improving the depth of RONS penetration and maximizing the survival of healthy cells, which contributes to the further clinical translation of plasma biomedicine.

Evaluating the Healing Potential of J-Plasma Scalpel-Created Surgical Incisions in Porcine and Rat Models

Cold atmospheric plasma devices generate reactive oxygen and nitrogen species that can be anti-microbial but also promote cell migration, differentiation, and tissue wound healing. This report investigates the healing of surgical incisions created using cold plasma generated by the J-Plasma scalpel (Precise Open handpiece, Apyx Medical, Inc.) compared to a steel scalpel in in vivo porcine and rat models. The J-Plasma scalpel is currently FDA approved for the delivery of helium plasma to cut, coagulate, and ablate soft tissue during surgical procedures. To our knowledge, this device has not been studied in creating surgical incisions but only during deeper dissection and hemostasis. External macroscopic and histologic grading by blinded reviewers revealed no significant difference in wound healing appearance or physiology in incisions created using the plasma scalpel as compared with a steel blade scalpel. Incisions created with the plasma scalpel also had superior hemostasis and a reduction in tissue and blood carryover. Scanning electron microscopy (SEM) and histology showed collagen fibril fusion occurred as the plasma scalpel incised through the tissue, contributing to a sealing effect. In addition, when bacteria were injected into the dermis before incision, the plasma scalpel disrupted the bacterial membrane as visualized in SEM images. External macroscopic and histologic grading by blinded reviewers revealed no significant difference in wound healing appearance or physiology. Based on these results, we propose additional studies to clinically evaluate the use of cold plasma in applications requiring hemostasis or when an increased likelihood of subdermal pathogen leakage could cause surgical site infection (i.e., sites with increased hair follicles).

No-ozone cold plasma induces apoptosis in human neuroblastoma cell line via increased intracellular reactive oxygen species (ROS)

BACKGROUND

This study aimed to evaluate the effect of argon-based No-ozone Cold Plasma (NCP) on neuroblastoma cancer cell apoptosis.

METHODS

Experiments were performed with SK-N-SH and HS 68. Cell cultures were treated with NCP for 1, 3, and 5 min. NCP was applied using three different strategies: direct NCP application to cell cultures, to only media, and to only cells. Evaluation of cell viability and the level of the reactive oxygen species (ROS) was performed. N-acetyl-L-cysteine (NAC) was also used to antagonize intracellular ROS. Cleaved caspase 3, PARP, aquaporin (AQP) 3 and 8 were detected.

RESULTS

NCP induced a gradual decrease in the SK-N-SH cell viability. In contrast, the viability of HS 68 cells did not change. SK-N-SH cells viability was reduced the most when the only media-NCP application strategy was employed. Intracellular ROS levels were significantly increased with time. Cleaved caspase 3 and PARP were increased at 6 h after NCP application. SK-N-SH cells remained viable with NAC after NCP application. AQP 3 and 8 were over-expressed in SK-N-SH cells.

CONCLUSION

These findings demonstrate the anti-cancer effect of NCP on neuroblastoma cells. NCP enhanced the selective apoptosis of neuroblastoma cells due to the increased intracellular ROS.

Synergistic Inhibitory Effect of Berberine and Low-Temperature Plasma on Non-Small-Cell Lung Cancer Cells via PI3K-AKT-Driven Signaling Axis

Low-temperature plasma (LTP) is an emerging biomedical technique that has been proposed as a potential approach for cancer therapy. Meanwhile, berberine (BER), an active ingredient extracted from various medical herbs, such as Coptischinesis, has been proven antitumor effects in a broad spectrum of cancer cells. In this study, we seek to develop a novel dual cancer therapeutic method by integrating pre-administration of BER and LTP exposure and evaluating its comprehensive antitumor effect on the human non-small-cell lung cancer (NSCLC) cell lines (A549 and H1299) in vitro. Cell viability, cell cycle, cell apoptosis, and intracellular and extracellular ROS were investigated. The results showed that cotreatment of BER and LTP significantly decreased the cell viability, arrested the cell cycle in the S phase, promoted cell apoptosis, and increased intracellular and extracellular ROS. Additionally, RNA Sequencing (RNA-Seq) technology was used to explore potential mechanisms. The differentially expressed genes among different treatment groups of NSCLC cells were analyzed and were mainly enriched in the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) signaling pathway. Moreover, cotreatment of BER and LTP notably depressed the total protein expression level of PI3K and AKT with immunoblotting. In conclusion, BER and LTP have a synergistic inhibitory effect on NSCLC cells via the PI3K-AKT signaling pathway, which could provide a promising strategy for supplementary therapy in the anti-NSCLC battle.

The Development of Nonthermal Plasma and Tirapazamine as a Novel Combination Therapy to Treat Melanoma In Situ

Although melanoma accounts for only 5.3% of skin cancer, it results in >75% of skin-cancer-related deaths. To avoid disfiguring surgeries on the head and neck associated with surgical excision, there is a clear unmet need for other strategies to selectively remove cutaneous melanoma lesions. Mohs surgery is the current treatment for cutaneous melanoma lesions and squamous and basal cell carcinoma. While Mohs surgery is an effective way to remove melanomas in situ, normal tissue is also excised to achieve histologically negative margins. This paper describes a novel combination therapy of nonthermal plasma (NTP) which emits a multitude of reactive oxygen species (ROS) and the injection of a pharmaceutical agent. We have shown that the effects of NTP are augmented by the DNA-damaging prodrug, tirapazamine (TPZ), which becomes a free radical only in conditions of hypoxemia, which is often enhanced in the tumor microenvironment. In this study, we demonstrate the efficacy of the combination therapy through experiments with B16-F10 and 1205 Lu metastatic melanoma cells both in vitro and in vivo. We also show the safety parameters of the therapy with no significant effects of the therapy when applied to porcine skin. We show the need for the intratumor delivery of TPZ in combination with the surface treatment of NTP and present a model of a medical device to deliver this combination therapy. The importance of functional gap junctions is indicated as a mechanism to promote the therapeutic effect. Collectively, the data support a novel therapeutic combination to treat melanoma and the development of a medical device to deliver the treatment in situ.

Anticancer Effect of Cold Atmospheric Plasma in Syngeneic Mouse Models of Melanoma and Colon Cancer

Cold atmospheric plasma (CAP) may have applications in treating various types of malignant tumors. This study assessed the anticancer effects of CAP using melanoma and colon cancer cell lines. CAP treatment significantly reduced the in vitro viability of melanoma and colon cancer cell lines and had a negligible effect on the viability of normal human melanocytes. Additionally, CAP and epidermal growth factor receptor (EGFR) inhibitor had an additive anticancer effect in a CAP-resistant melanoma cell line. Reactive oxygen and nitrogen species known to be generated by CAP enhanced the anticancer effects of CAP and EGFR inhibitors. The in vivo anticancer activities of CAP were evaluated by testing its effects against syngeneic tumors induced in mice by melanoma and colon cancer cells. CAP treatment reduced tumor volume and weight in both cancer models, with the extent of tumor reduction dependent on the duration and number of CAP treatments. Histologic examination also revealed the tumoricidal effects of CAP in both tumor models. In conclusion, CAP inhibits the growth of mouse melanoma and colon cancer cell lines in vitro and shows tumoricidal effects against mouse models of melanoma and colon cancer in vivo.

Low Temperature Plasma Suppresses Lung Cancer Cells Growth via VEGF/VEGFR2/RAS/ERK Axis

Low temperature plasma (LTP) is a promising cancer therapy in clinical practice. In this study, dielectric barrier discharge plasma with helium gas was used to generate LTP. Significant increases in extracellular and intracellular reactive species were found in lung cancer cells (CALU-1 and SPC-A1) after LTP treatments. Cells viability and apoptosis assays demonstrated that LTP inhibited cells viability and induced cells death, respectively. Moreover, Western blotting revealed that the growth of CALU-1 cells was suppressed by LTP via the VEGF/VEGFR2/RAS/ERK axis for the first time. The results showed that LTP-induced ROS and RNS could inhibit the growth of lung cancer cells via VEGF/VEGFR2/RAS/ERK axis. These findings advance our understanding of the inhibitory mechanism of LTP on lung cancer and will facilitate its clinical application.

The effect of local non-thermal plasma therapy on the cancer-immunity cycle in a melanoma mouse model

Melanoma remains a deadly cancer despite significant advances in immune checkpoint blockade and targeted therapies. The incidence of melanoma is also growing worldwide, which highlights the need for novel treatment options and strategic combination of therapies. Here, we investigate non-thermal plasma (NTP), an ionized gas, as a promising, therapeutic option. In a melanoma mouse model, direct treatment of tumors with NTP results in reduced tumor burden and prolonged survival. Physical characterization of NTP treatment in situ reveals the deposited NTP energy and temperature associated with therapy response, and whole transcriptome analysis of the tumor identified several modulated pathways. NTP treatment also enhances the cancer-immunity cycle, as immune cells in both the tumor and tumor-draining lymph nodes appear more stimulated to perform their anti-cancer functions. Thus, our data suggest that local NTP therapy stimulates systemic, anti-cancer immunity. We discuss, in detail, how these fundamental insights will help direct the translation of NTP technology into the clinic and inform rational combination strategies to address the challenges in melanoma therapy.

Preclinical Cold Atmospheric Plasma Cancer Treatment

Simple Summary

Cold atmospheric plasma (CAP) is generated in a rapid yet low-energy input streamer-discharge process at atmospheric pressure conditions. CAP is an ionized gas with a low ionization level and plenty of reactive species and radicals. These reactive components, and their near-room temperature nature, make CAP a powerful tool in medical applications, particularly cancer therapy. Here, we summarized the latest development and status of preclinical applications of CAP in cancer therapy, which may guide further clinical studies of CAP-based cancer therapy.

Abstract

CAP is an ionized gas generated under atmospheric pressure conditions. Due to its reactive chemical components and near-room temperature nature, CAP has promising applications in diverse branches of medicine, including microorganism sterilization, biofilm inactivation, wound healing, and cancer therapy. Currently, hundreds of in vitro demonstrations of CAP-based cancer treatments have been reported. However, preclinical studies, particularly in vivo studies, are pivotal to achieving a final clinical application. Here, we comprehensively introduced the research status of the preclinical usage of CAP in cancer treatment, by primarily focusing on the in vivo studies over the past decade. We summarized the primary research strategies in preclinical and clinical studies, including transdermal CAP treatment, post-surgical CAP treatment, CAP-activated solutions treatment, and sensitization treatment to drugs. Finally, the underlying mechanism was discussed based on the latest understanding.

Cold Atmospheric Plasma Ameliorates Skin Diseases Involving Reactive Oxygen/Nitrogen Species-Mediated Functions

Skin diseases are mainly divided into infectious diseases, non-infectious inflammatory diseases, cancers, and wounds. The pathogenesis might include microbial infections, autoimmune responses, aberrant cellular proliferation or differentiation, and the overproduction of inflammatory factors. The traditional therapies for skin diseases, such as oral or topical drugs, have still been unsatisfactory, partly due to systematic side effects and reappearance. Cold atmospheric plasma (CAP), as an innovative and non-invasive therapeutic approach, has demonstrated its safe and effective functions in dermatology. With its generation of reactive oxygen species and reactive nitrogen species, CAP exhibits significant efficacies in inhibiting bacterial, viral, and fungal infections, facilitating wound healing, restraining the proliferation of cancers, and ameliorating psoriatic or vitiligous lesions. This review summarizes recent advances in CAP therapies for various skin diseases and implicates future strategies for increasing effectiveness or broadening clinical indications.

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.

Cold Atmospheric Plasma Attenuates Breast Cancer Cell Growth Through Regulation of Cell Microenvironment Effectors

Breast cancer exists in multiple subtypes some of which still lack a targeted and effective therapy. Cold atmospheric plasma (CAP) has been proposed as an emerging anti-cancer treatment modality. In this study, we investigated the effects of direct and indirect CAP treatment driven by the advantageous nanosecond pulsed discharge on breast cancer cells of different malignant phenotypes and estrogen receptor (ER) status, a major factor in the prognosis and therapeutic management of breast cancer. The main CAP reactive species in liquid (i.e. H2O2, NO2−/NO3−) and gas phase were determined as a function of plasma operational parameters (i.e. treatment time, pulse voltage and frequency), while pre-treatment with the ROS scavenger NAC revealed the impact of ROS in the treatment. CAP treatment induced intense phenotypic changes and apoptosis in both ER+ and ER- cells, which is associated with the mitochondrial pathway as evidenced by the increased Bax/Bcl-2 ratio and cleavage of PARP-1. Interestingly, CAP significantly reduced CD44 protein expression (a major cancer stem cell marker and matrix receptor), while differentially affected the expression of proteases and inflammatory mediators. Collectively, the findings of the present study suggest that CAP suppresses breast cancer cell growth and regulates several effectors of the tumor microenvironment and thus it could represent an efficient therapeutic approach for distinct breast cancer subtypes.

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.

Multimodal Imaging Techniques to Evaluate the Anticancer Effect of Cold Atmospheric Pressure Plasma

BACKGROUND

Skin cancer is the most frequent cancer worldwide and is divided into non-melanoma skin cancer, including basal cell carcinoma, as well as squamous cell carcinoma (SCC) and malignant melanoma (MM).

METHODS

This study evaluates the effects of cold atmospheric pressure plasma (CAP) on SCC and MM in vivo, employing a comprehensive approach using multimodal imaging techniques. Longitudinal MR and PET/CT imaging were performed to determine the anatomic and metabolic tumour volume over three-weeks in vivo. Additionally, the formation of reactive species after CAP treatment was assessed by non-invasive chemiluminescence imaging of L-012. Histological analysis and immunohistochemical staining for Ki-67, ApopTag®, F4/80, CAE, and CD31, as well as protein expression of PCNA, caspase-3 and cleaved-caspase-3, were performed to study proliferation, apoptosis, inflammation, and angiogenesis in CAP-treated tumours.

RESULTS

As the main result, multimodal in vivo imaging revealed a substantial reduction in tumour growth and an increase in reactive species after CAP treatment, in comparison to untreated tumours. In contrast, neither the markers for apoptosis, nor the metabolic activity of both tumour entities was affected by CAP.

CONCLUSIONS

These findings propose CAP as a potential adjuvant therapy option to established standard therapies of skin cancer.

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.

The Antitumor Effects of Plasma-Activated Saline on Muscle-Invasive Bladder Cancer Cells In Vitro and In Vivo Demonstrate Its Feasibility as a Potential Therapeutic Approach

Muscle-invasive bladder cancer (MIBC) is a fast-growing and aggressive malignant tumor in urinary system. Since chemotherapy and immunotherapy are only useable with a few MIBC patients, the clinical treatment of MIBC still faces challenges. Here, we examined the feasibility of plasma-activated saline (PAS) as a fledgling therapeutic strategy for MIBC treatment. Our data showed that plasma irradiation could generate a variety of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in saline. In vivo tests revealed that pericarcinomatous tissue injection with PAS was effective at preventing subcutaneous bladder tumor growth, with no side effects to the visceral organs after long-term administration, as well as having no obvious influence on the various biochemistry indices of the blood in mice. The in vitro studies indicated that adding 30% PAS in cell culture media causes oxidative damage to the bladder transitional cells T24 and J82 through enhancing the intracellular ROS level, and eventually induces cancer cells' apoptosis by activating the ROS-mediated Fas/CD95 pathway. Therefore, for an intracavity tumor, these initial observations suggest that the soaking of the tumor tissue with PAS by intravesical perfusion may be a novel treatment option for bladder cancer.

Non-thermal plasma modulates cellular markers associated with immunogenicity in a model of latent HIV-1 infection

Effective control of infection by human immunodeficiency virus type 1 (HIV-1), the causative agent of the acquired immunodeficiency syndrome (AIDS), requires continuous and life-long use of anti-retroviral therapy (ART) by people living with HIV-1 (PLWH). In the absence of ART, HIV-1 reemergence from latently infected cells is ineffectively suppressed due to suboptimal innate and cytotoxic T lymphocyte responses. However, ART-free control of HIV-1 infection may be possible if the inherent immunological deficiencies can be reversed or restored. Herein we present a novel approach for modulating the immune response to HIV-1 that involves the use of non-thermal plasma (NTP), which is an ionized gas containing various reactive oxygen and nitrogen species (RONS). J-Lat cells were used as a model of latent HIV-1 infection to assess the effects of NTP application on viral latency and the expression of pro-phagocytic and pro-chemotactic damage-associated molecular patterns (DAMPs). Exposure of J-Lat cells to NTP resulted in stimulation of HIV-1 gene expression, indicating a role in latency reversal, a necessary first step in inducing adaptive immune responses to viral antigens. This was accompanied by the release of pro-inflammatory cytokines and chemokines including interleukin-1β (IL-1β) and interferon-γ (IFN-γ); the display of pro-phagocytic markers calreticulin (CRT), heat shock proteins (HSP) 70 and 90; and a correlated increase in macrophage phagocytosis of NTP-exposed J-Lat cells. In addition, modulation of surface molecules that promote or inhibit antigen presentation was also observed, along with an altered array of displayed peptides on MHC I, further suggesting methods by which NTP may modify recognition and targeting of cells in latent HIV-1 infection. These studies represent early progress toward an effective NTP-based ex vivo immunotherapy to resolve the dysfunctions of the immune system that enable HIV-1 persistence in PLWH.

Cold Atmospheric Plasma as a Novel Therapeutic Tool for the Treatment of Brain Cancer

BACKGROUND

Studies from the past few years revealed the importance of Cold Atmospheric Plasma (CAP) on various kinds of diseases, including brain cancers or glioblastoma (GBM), and hence coined a new term 'Plasma Medicine' in the modern world for promising therapeutic approaches. Here, we focus on the efficacy of CAP and its liquid derivatives on direct interactions or with specific nanoparticles to show pivotal roles in brain cancer treatment.

METHOD

In the present review study, the authors studied several articles over the past decades published on the types of CAP and its effects on different brain cancers and therapy.

RESULTS

A growing body of evidence indicates that CAP and its derivatives like Plasma Activated Media/ Water (PAM/PAW) are introduced in different kinds of GBM. Recent studies proposed that CAP plays a remarkable role in GBM treatment. To increase the efficacy of CAP, various nanoparticles of different origins got specific attention in recent times. In this review, different strategies to treat brain cancers, including nanoparticles, are discussed as enhancers of CAP induced targeted nanotherapeutic approach.

CONCLUSION

CAP treatment and its synergistic effects with different nanoparticles hold great promise for clinical applications in early diagnosis and treatment of GBM treatment. However, results obtained from previous studies were still in the preliminary phase, and there must be a concern over the use of optimal methods for a dosage of CAP and nanoparticles for complete cure of GBM.

Local and Targeted Delivery of Immune Checkpoint Blockade Therapeutics

Immune checkpoint blockade (ICB) therapy elicits antitumor response by inhibiting immune suppressor components, including programmed cell death protein 1 and its ligand (PD-1/PD-L1) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4). Despite improved therapeutic efficacy, the clinical response rate is still unsatisfactory as revealed by the fact that only a minority of patients experience durable benefits. Additionally, "off-target" effects after systemic administration remain challenging for ICB treatment. To this end, the local and targeted delivery of ICB agents instead could be a potential solution to maximize the therapeutic outcomes while minimizing the side effects.In this Account, our recent studies directed at the development of different strategies for the local and targeted delivery of ICB agents are discussed. For example, transdermal microneedle patches loaded with anti-programmed death-1 antibody (aPD1) and anti-CTLA4 were developed to facilitate sustained release of ICB agents at the diseased sites. Triggered release could also be achieved by various stimuli within the tumor microenvironment, including low pH and abnormally expressed enzymes. Recently, the combination of an anti-programmed death-ligand 1 antibody (aPD-L1) loaded hollow-structured microneedle patch with cold atmospheric plasma (CAP) therapy was also reported. Microneedles provided microchannels to facilitate the transdermal transport of CAP and further induce immunogenic tumor cell death, which could be synergized by the local release of aPD-L1. In addition, in situ formed injectable or sprayable hydrogels were tailored to deliver immunomodulatory antibodies to the surgical bed to inhibit tumor recurrence after primary tumor resection. In paralell, inspired by the unique targeting ability of platelets toward the inflammatory sites, we engineered natural platelets decorated with aPD-L1 for targeted delivery after tumor resection to inhibit tumor recurrence. We further constructed a cell-cell combination delivery platform based on conjugates of platelets and hematopoietic stem cells (HSCs) for leukemia treatment. With the homing ability of HSCs to the bone marrow, the HSC-platelet-aPD1 assembly could effectively deliver aPD1 in an acute myeloid leukemia mouse model. Besides living cells, we also leveraged HEK293T-derived vesicles with PD1 receptors on their surfaces to disrupt the PD-1/PD-L1 immune inhibitory pathway. Moreover, the inner space of the vesicles allowed the packaging of an indoleamine 2,3-dioxygenase inhibitor, further reinforcing the therapeutic efficacy. A similar approach has also been demonstrated by genetically engineering platelets overexpressing PD1 receptor for postsurgical treatment. We hope the local and targeted ICB agent delivery methods introduced in this collection would further inspire the development of advanced drug delivery strategies to improve the efficiency of cancer treatment while alleviating side effects.

Cold Atmospheric Pressure Plasma in Wound Healing and Cancer Treatment

Plasma medicine is gaining increasing attention and is moving from basic research into clinical practice. While areas of application are diverse, much research has been conducted assessing the use of cold atmospheric pressure plasma (CAP) in wound healing and cancer treatment—two applications with entirely different goals. In wound healing, a tissue-stimulating effect is intended, whereas cancer therapy aims at killing malignant cells. In this review, we provide an overview of the latest clinical and some preclinical research on the efficacy of CAP in wound healing and cancer therapy. Furthermore, we discuss the current understanding of molecular signaling mechanisms triggered by CAP that grant CAP its antiseptic and tissue regenerating or anti-proliferative and cell death-inducing properties. For the efficacy of CAP in wound healing, already substantial evidence from clinical studies is available, while evidence for therapeutic effects of CAP in oncology is mainly from in vitro and in vivo animal studies. Efforts to elucidate the mode of action of CAP suggest that different components, such as ultraviolet (UV) radiation, electromagnetic fields, and reactive species, may act synergistically, with reactive species being regarded as the major effector by modulating complex and concentration-dependent redox signaling pathways.

Experimentelle Forschung an der Klinik und Poliklinik für Dermatologie und Venerologie

Seit Antritt von Prof. Dr. med. Steffen Emmert als Ordinarius der Klinik und Poliklinik für Dermatologie und Venerologie im Jahr 2015 konnte das dermatologische Forschungslabor sukzessive aufgebaut und erweitert werden. Im Einklang mit dem onkologischen Schwerpunkt der Universitätsmedizin Rostock sowie dem von der Landesregierung forcierten „Gesundheitsland Mecklenburg-Vorpommern“ wird grundlagenorientierten und translationalen Projekten nachgegangen. Das vorwiegend drittmittelfinanzierte und stetig wachsende Forschungsteam bearbeitet diverse Fragestellungen in den Bereichen der Dermato-Onkologie, Plasmamedizin und seltenen Hauterkrankungen. Inzwischen auf einem soliden Fundament stehend, befindet sich der Forschungsbereich weiterhin in einem dynamischen Entwicklungsprozess. Nicht nur personell, sondern auch thematisch und methodisch wird er derzeit durch die Integration weiterer Arbeitsgruppen unter der Leitung von Ärzten aus der Klinik ergänzt und ausgebaut. Diverse Kollaborationen an der Universitätsmedizin Rostock und im Land zeugen von einem freundlichen, unterstützenden und kollegialen Umfeld, das die Integration am Standort befördert hat.

Large-Scale Image Analysis for Investigating Spatio-Temporal Changes in Nuclear DNA Damage Caused by Nitrogen Atmospheric Pressure Plasma Jets

The effective clinical application of atmospheric pressure plasma jet (APPJ) treatments requires a well-founded methodology that can describe the interactions between the plasma jet and a treated sample and the temporal and spatial changes that result from the treatment. In this study, we developed a large-scale image analysis method to identify the cell-cycle stage and quantify damage to nuclear DNA in single cells. The method was then tested and used to examine spatio-temporal distributions of nuclear DNA damage in two cell lines from the same anatomic location, namely the oral cavity, after treatment with a nitrogen APPJ. One cell line was malignant, and the other, nonmalignant. The results showed that DNA damage in cancer cells was maximized at the plasma jet treatment region, where the APPJ directly contacted the sample, and declined radially outward. As incubation continued, DNA damage in cancer cells decreased slightly over the first 4 h before rapidly decreasing by approximately 60% at 8 h post-treatment. In nonmalignant cells, no damage was observed within 1 h after treatment, but damage was detected 2 h after treatment. Notably, the damage was 5-fold less than that detected in irradiated cancer cells. Moreover, examining damage with respect to the cell cycle showed that S phase cells were more susceptible to DNA damage than either G1 or G2 phase cells. The proposed methodology for large-scale image analysis is not limited to APPJ post-treatment applications and can be utilized to evaluate biological samples affected by any type of radiation, and, more so, the cell-cycle classification can be used on any cell type with any nuclear DNA staining.

[Current indications for plasma therapy in dermatology]

BACKGROUND

Plasma medicine is gaining increasing interest and provides a multitude of dermatological applications. Cold atmospheric pressure plasma (CAP) can be used in clinical applications without harming the treated tissue or in a tissue destructive manner. It consists of a complex mixture of biologically active agents, which can act synergistically on the treated material or tissue.

OBJECTIVES

A summary of the current research findings regarding dermatological applications of CAP is provided.

METHODS

Literature on CAP applications in dermatology has been screened and summarized.

RESULTS

CAP exerts antimicrobial, tissue-stimulating, blood-flow-stimulating but also pro-apoptotic effects. By exploiting these properties, CAP is successfully applied for disinfection and treatment of chronic ulcerations. Furthermore, positive effects of CAP have been shown for the treatment of tumors, actinic keratosis, scars, ichthyosis, atopic eczema as well as for alleviation of pain and itch.

CONCLUSIONS

While the use of CAP for disinfection and wound treatment has already moved into clinical practice, further applications such as cancer treatment are still exploratory.

Non-Thermal Atmospheric Pressure Bio-Compatible Plasma Stimulates Apoptosis via p38/MAPK Mechanism in U87 Malignant Glioblastoma

Nonthermal plasma is a promising novel therapy for the alteration of biological and clinical functions of cells and tissues, including apoptosis and inhibition of tumor progression. This therapy generates reactive oxygen and nitrogen species (RONS), which play a major role in anticancer effects. Previous research has verified that plasma jets can selectively induce apoptosis in various cancer cells, suggesting that it could be a potentially effective novel therapy in combination with or as an alternative to conventional therapeutic methods. In this study, we determined the effects of nonthermal air soft plasma jets on a U87 MG brain cancer cell line, including the dose- and time-dependent effects and the physicochemical and biological correlation between the RONS cascade and p38/mitogen-activated protein kinase (MAPK) signaling pathway, which contribute to apoptosis. The results indicated that soft plasma jets efficiently inhibit cell proliferation and induce apoptosis in U87 MG cells but have minimal effects on astrocytes. These findings revealed that soft plasma jets produce a potent cytotoxic effect via the initiation of cell cycle arrest and apoptosis. The production of reactive oxygen species (ROS) in cells was tested, and an intracellular ROS scavenger, N-acetyl cysteine (NAC), was examined. Our results suggested that soft plasma jets could potentially be used as an effective approach for anticancer therapy.

Non-Thermal Plasma-Induced Immunogenic Cell Death in Cancer: A Topical Review

Recent advances in biomedical research in cancer immunotherapy have identified the use of an oxidative stress-based approach to treat cancers, which works by inducing immunogenic cell death (ICD) in cancer cells. Since the anti-cancer effects of non-thermal plasma (NTP) are largely attributed to the reactive oxygen and nitrogen species that are delivered to and generated inside the target cancer cells, it is reasonable to postulate that NTP would be an effective modality for ICD induction. NTP treatment of tumors has been shown to destroy cancer cells rapidly and, under specific treatment regimens, this leads to systemic tumor-specific immunity. The translational benefit of NTP for treatment of cancer relies on its ability to enhance the interactions between NTP-exposed tumor cells and local immune cells which initiates subsequent protective immune responses. This review discusses results from recent investigations of NTP application to induce immunogenic cell death in cancer cells. With further optimization of clinical devices and treatment protocols, NTP can become an essential part of the therapeutic armament against cancer.

Cold atmospheric plasma is a viable solution for treating orthopedic infection: a review

Bacterial infection and antibiotic resistance are major threats to human health and very few solutions are available to combat this eventuality. A growing number of studies indicate that cold (non-thermal) plasma treatment can be used to prevent or eliminate infection from bacteria, bacterial biofilms, fungi and viruses. Mechanistically, a cold plasma discharge is composed of high-energy electrons that generate short-lived reactive oxygen and nitrogen species which further react to form more stable compounds (NO2, H2O2, NH2Cl and others) depending on the gas mixture and plasma parameters. Cold plasma devices are being developed for medical applications including infection, cancer, plastic surgery applications and more. Thus, in this review we explore the potential utility of cold plasma as a non-antibiotic approach for treating post-surgical orthopedic infections.

Physical plasma and leukocytes - immune or reactive?

Leukocytes are professionals in recognizing and removing pathogenic or unwanted material. They are present in virtually all tissues, and highly motile to enter or leave specific sites throughout the body. Less than a decade ago, physical plasmas entered the field of medicine to deliver their delicate mix of reactive species and other physical agents for mainly dermatological or oncological therapy. Plasma treatment thus affects leukocytes via direct or indirect means: immune cells are either present in tissues during treatment, or infiltrate or exfiltrate plasma-treated areas. The immune system is crucial for human health and resolution of many types of diseases. It is therefore vital to study the response of leukocytes after plasma treatment in vitro and in vivo. This review gathers together the major themes in the plasma treatment of innate and adaptive immune cells, and puts these into the context of wound healing and oncology, the two major topics in plasma medicine.

Cold atmospheric plasma treatment inhibits growth in colorectal cancer cells

Plasma oncology is a relatively new field of research. Recent developments have indicated that cold atmospheric plasma (CAP) technology is an interesting new therapeutic approach to cancer treatment. In this study, p53 wildtype (LoVo) and human p53 mutated (HT29 and SW480) colorectal cancer cells were treated with the miniFlatPlaSter - a device particularly developed for the treatment of tumor cells - that uses the Surface Micro Discharge (SMD) technology for plasma production in air. The present study analyzed the effects of plasma on colorectal cancer cells in vitro and on normal colon tissue ex vivo. Plasma treatment had strong effects on colon cancer cells, such as inhibition of cell proliferation, induction of cell death and modulation of p21 expression. In contrast, CAP treatment of murine colon tissue ex vivo for up to 2 min did not show any toxic effect on normal colon cells compared to H2O2 positive control. In summary, these results suggest that the miniFlatPlaSter plasma device is able to kill colorectal cancer cells independent of their p53 mutation status. Thus, this device presents a promising new approach in colon cancer therapy.

Non-thermal plasma induces immunogenic cell death in vivo in murine CT26 colorectal tumors

Immunogenic cell death is characterized by the emission of danger signals that facilitate activation of an adaptive immune response against dead-cell antigens. In the case of cancer therapy, tumor cells undergoing immunogenic death promote cancer-specific immunity. Identification, characterization, and optimization of stimuli that induce immunogenic cancer cell death has tremendous potential to improve the outcomes of cancer therapy. In this study, we show that non-thermal, atmospheric pressure plasma can be operated to induce immunogenic cell death in an animal model of colorectal cancer. In vitro, plasma treatment of CT26 colorectal cancer cells induced the release of classic danger signals. Treated cells were used to create a whole-cell vaccine which elicited protective immunity in the CT26 tumor mouse model. Moreover, plasma treatment of subcutaneous tumors elicited emission of danger signals and recruitment of antigen presenting cells into tumors. An increase in T cell responses targeting the colorectal cancer-specific antigen guanylyl cyclase C (GUCY2C) were also observed. This study provides the first evidence that non-thermal plasma is a bone fide inducer of immunogenic cell death and highlights its potential for clinical translation for cancer immunotherapy.

The Emerging Role of Gas Plasma in Oncotherapy

Atmospheric pressure gas plasmas are emerging as a promising treatment in cancer that can supplement the existing set of treatment modalities and, when combined with other therapies, enhance their selectivity and efficacy against resistant cancers. With further optimisation in production and administration of plasma treatment, plasma-enabled therapy has a strong potential to mature as a tool for selectively curing highly resistant solid tumours. Although intense preclinical studies have been conducted to exploit the unique traits of plasma as an oncotherapy, few clinical studies are underway. This review identifies types of cancers and patient groups that most likely benefit from plasma oncotherapy, to introduce clinical practitioners to plasma therapy and accelerate the speed of translating plasma for cancer control in clinics.

Cold atmospheric plasma, a novel promising anti-cancer treatment modality

Over the past decade, cold atmospheric plasma (CAP), a near room temperature ionized gas has shown its promising application in cancer therapy. Two CAP devices, namely dielectric barrier discharge and plasma jet, show significantly anti-cancer capacity over dozens of cancer cell lines in vitro and several subcutaneous xenograft tumors in vivo. In contrast to conventional anti-cancer approaches and drugs, CAP is a selective anti-cancer treatment modality. Thus far establishing the chemical and molecular mechanism of the anti-cancer capacity of CAP is far from complete. In this review, we provide a comprehensive introduction of the basics of CAP, state of the art research in this field, the primary challenges, and future directions to cancer biologists.

Cold Atmospheric Plasma in the Treatment of Osteosarcoma

Human osteosarcoma (OS) is the most common primary malignant bone tumor occurring most commonly in adolescents and young adults. Major improvements in disease-free survival have been achieved by implementing a combination therapy consisting of radical surgical resection of the tumor and systemic multi-agent chemotherapy. However, long-term survival remains poor, so novel targeted therapies to improve outcomes for patients with osteosarcoma remains an area of active research. This includes immunotherapy, photodynamic therapy, or treatment with nanoparticles. Cold atmospheric plasma (CAP), a highly reactive (partially) ionized physical state, has been shown to inherit a significant anticancer capacity, leading to a new field in medicine called “plasma oncology.” The current article summarizes the potential of CAP in the treatment of human OS and reviews the underlying molecular mode of action.

The Strong Cell-based Hydrogen Peroxide Generation Triggered by Cold Atmospheric Plasma

Hydrogen peroxide (H₂O₂) is an important signaling molecule in cancer cells. However, the significant secretion of H₂O₂ by cancer cells have been rarely observed. Cold atmospheric plasma (CAP) is a near room temperature ionized gas composed of neutral particles, charged particles, reactive species, and electrons. Here, we first demonstrated that breast cancer cells and pancreatic adenocarcinoma cells generated micromolar level H₂O₂ during just 1 min of direct CAP treatment on these cells. The cell-based H₂O₂ generation is affected by the medium volume, the cell confluence, as well as the discharge voltage. The application of cold atmospheric plasma (CAP) in cancer treatment has been intensively investigated over the past decade. Several cellular responses to CAP treatment have been observed including the consumption of the CAP-originated reactive species, the rise of intracellular reactive oxygen species, the damage on DNA and mitochondria, as well as the activation of apoptotic events. This is a new previously unknown cellular response to CAP, which provides a new prospective to understand the interaction between CAP and cells in vitro and in vivo. The short-lived reactive species in CAP may activate cells in vivo to generate long-lived reactive species such as H₂O₂, which may trigger immune attack on tumorous tissues via the H₂O₂-mediated lymphocyte activation.

Cold Atmospheric Plasma Induces Apoptosis and Oxidative Stress Pathway Regulation in T-Lymphoblastoid Leukemia Cells

Cold atmospheric plasma (CAP) has shown its antitumor activity in both in vitro and in vivo systems. However, the mechanisms at the basis of CAP-cell interaction are not yet completely understood. The aim of this study is to investigate CAP proapoptotic effect and identify some of the molecular mechanisms triggered by CAP in human T-lymphoblastoid leukemia cells. CAP treatment was performed by means of a wand electrode DBD source driven by nanosecond high-voltage pulses under different operating conditions. The biological endpoints were assessed through flow cytometry and real-time PCR. CAP caused apoptosis in Jurkat cells mediated by p53 upregulation. To test the involvement of intrinsic and/or extrinsic pathway, the expression of Bax/Bcl-2 and caspase-8 was analyzed. The activation of caspase-8 and the upregulation of Bax and Bcl-2 were observed. Moreover, CAP treatment increased ROS intracellular level. The situation reverts after a longer time of treatment. This is probably due to compensatory cellular mechanisms such as the posttranscriptional upregulation of SOD1, CAT, and GSR2. According to ROS increase, CAP induced a significant increase in DNA damage at all treatment conditions. In conclusion, our results provide a deeper understanding of CAP potential in the oncological field and pose the basis for the evaluation of its toxicological profile.

Nanosecond-Pulsed DBD Plasma-Generated Reactive Oxygen Species Trigger Immunogenic Cell Death in A549 Lung Carcinoma Cells through Intracellular Oxidative Stress

A novel application for non-thermal plasma is the induction of immunogenic cancer cell death for cancer immunotherapy. Cells undergoing immunogenic death emit danger signals which facilitate anti-tumor immune responses. Although pathways leading to immunogenic cell death are not fully understood; oxidative stress is considered to be part of the underlying mechanism. Here; we studied the interaction between dielectric barrier discharge plasma and cancer cells for oxidative stress-mediated immunogenic cell death. We assessed changes to the intracellular oxidative environment after plasma treatment and correlated it to emission of two danger signals: surface-exposed calreticulin and secreted adenosine triphosphate. Plasma-generated reactive oxygen and charged species were recognized as the major effectors of immunogenic cell death. Chemical attenuators of intracellular reactive oxygen species successfully abrogated oxidative stress following plasma treatment and modulated the emission of surface-exposed calreticulin. Secreted danger signals from cells undergoing immunogenic death enhanced the anti-tumor activity of macrophages. This study demonstrated that plasma triggers immunogenic cell death through oxidative stress pathways and highlights its potential development for cancer immunotherapy.

Safety aspects of atmospheric pressure helium plasma jet operation on skin: In vivo study on mouse skin

Biomedical applications of plasma require its efficacy for specific purposes and equally importantly its safety. Herein the safety aspects of cold plasma created with simple atmospheric pressure plasma jet produced with helium gas and electrode discharge are evaluated in skin damage on mouse, at different duration of exposure and gas flow rates. The extent of skin damage and treatments are systematically evaluated using stereomicroscope, labelling with fluorescent dyes, histology, infrared imaging and optical emission spectroscopy. The analyses reveal early and late skin damages as a consequence of plasma treatment, and are attributed to direct and indirect effects of plasma. The results indicate that direct skin damage progresses with longer treatment time and increasing gas flow rates which reflect changes in plasma properties. With increasing flow rates, the temperature on treated skin grows and the RONS formation rises. The direct effects were plasma treatment dependent, whereas the disclosed late—secondary effects were more independent on discharge parameters and related to diffusion of RONS species. Thermal effects and skin heating are related to plasma-coupling properties and are separated from the effects of other RONS. It is demonstrated that cumulative topical treatment with helium plasma jet could lead to skin damage. How these damages can be mitigated is discussed in order to provide guidance, when using atmospheric pressure plasma jets for skin treatments.

Chemical modification of extracellular matrix by cold atmospheric plasma-generated reactive species affects chondrogenesis and bone formation

The goal of this study was to investigate whether cold plasma generated by dielectric barrier discharge (DBD) modifies extracellular matrices (ECM) to influence chondrogenesis and endochondral ossification. Replacement of cartilage by bone during endochondral ossification is essential in fetal skeletal development, bone growth and fracture healing. Regulation of this process by the ECM occurs through matrix remodelling, involving a variety of cell attachment molecules and growth factors, which influence cell morphology and protein expression. The commercially available ECM, Matrigel, was treated with microsecond or nanosecond pulsed (μsp or nsp, respectively) DBD frequencies conditions at the equivalent frequencies (1 kHz) or power (~1 W). Recombinant human bone morphogenetic protein-2 was added and the mixture subcutaneously injected into mice to simulate ectopic endochondral ossification. Two weeks later, the masses were extracted and analysed by microcomputed tomography. A significant increase in bone formation was observed in Matrigel treated with μsp DBD compared with control, while a significant decrease in bone formation was observed for both nsp treatments. Histological and immunohistochemical analysis showed Matrigel treated with μsp plasma increased the number of invading cells, the amount of vascular endothelial growth factor and chondrogenesis while the opposite was true for Matrigel treated with nsp plasma. In support of the in vivo Matrigel study, 10 T1/2 cells cultured in vitro on μsp DBD-treated type I collagen showed increased expression of adhesion proteins and activation of survival pathways, which decreased with nsp plasma treatments. These results indicate DBD modification of ECM can influence cellular behaviours to accelerate or inhibit chondrogenesis and endochondral ossification. Copyright © 2016 John Wiley & Sons, Ltd.