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- ItemPotentiating anti-tumor immunity with physical plasma(Amsterdam [u.a.] : Elsevier, 2018) Bekeschus, Sander; Clemen, Ramona; Metelmann, Hans-RobertThe age of checkpoint blockage emphasizes the importance of adaptive antitumor immune responses. This arm of immune defense is key in recognizing molecules via specific receptors to distinguish between self and foreign or mutated structures. Antigen-specific T-cells identify non-self epitopes, tumor-associated antigens, or neoepitopes on tumors to carry out attacks on malignant cells. Although tumor cells are immunogenic by nature, they have developed strategies to evade an immune response that would otherwise facilitate their clearance. Several steps in antitumor immunity utilize the toxic and signaling properties of reactive oxygen and nitrogen species (ROS/RNS). Cold physical plasmas are potent generators of such ROS/RNS and are demonstrated to have profound antitumor activity in vitro and in vivo. Here we discuss recent evidence and concepts on how plasmas may boost immunity against pathological cells. Specifically, plasma treatment may enhance the immunogenicity of tumor cells by induction of the immunogenic cancer cell death (ICD) and redox regulation of the antigen-presenting machinery. These aspects provide a rationale for localized plasma-based onco-therapies enhancing systemic antitumor immunity, which eventually may target distant tumor metastasis in cancer patients in a T-cell dependent fashion.
- ItemCell cycle-related genes associate with sensitivity to hydrogen peroxide-induced toxicity(Amsterdam [u.a.] : Elsevier, 2022) Bekeschus, Sander; Liebelt, Grit; Menz, Jonas; Singer, Debora; Wende, Kristian; Schmidt, AnkeReactive oxygen species (ROS) such as hydrogen peroxide (H2O2) are well-described agents in physiology and pathology. Chronic inflammation causes incessant H2O2 generation associated with disease occurrences such as diabetes, autoimmunity, and cancer. In cancer, conditioning of the tumor microenvironment, e.g., hypoxia and ROS generation, has been associated with disease outcomes and therapeutic efficacy. Many reports have investigated the roles of the action of H2O2 across many cell lines and disease models. The genes predisposing tumor cell lines to H2O2-mediated demise are less deciphered, however. To this end, we performed in-house transcriptional profiling of 35 cell lines and simultaneously investigated each cell line's H2O2 inhibitory concentration (IC25) based on metabolic activity. More than 100-fold differences were observed between the most resistant and sensitive cell lines. Correlation and gene ontology pathway analysis identified a rigid association with genes intertwined in cell cycle progression and proliferation, as such functional categories dominated the top ten significant processes. The ten most substantially correlating genes (Spearman r > 0.70 or < -0.70) were validated using qPCR, showing complete congruency with microarray analysis findings. Western blotting confirmed the correlation of cell cycle-related proteins negatively correlating with H2O2 IC25. Top genes related to ROS production or antioxidant defense were only modest in correlation (Spearman r > 0.40 or < -0.40). In conclusion, our in-house transcriptomic correlation analysis revealed a set of cell cycle-associated genes associated with a priori resistance or sensitivity to H2O2-induced cellular demise with the detailed and causative roles of individual genes remaining unclear.
- ItemMedical gas plasma augments bladder cancer cell toxicity in preclinical models and patient-derived tumor tissues(Amsterdam [u.a.] : Elsevier, 2022) Gelbrich, Nadine; Miebach, Lea; Berner, Julia; Freund, Eric; Saadati, Fariba; Schmidt, Anke; Stope, Matthias; Zimmermann, Uwe; Burchardt, Martin; Bekeschus, SanderIntroduction: Medical gas plasma therapy has been successfully applied to several types of cancer in preclinical models. First palliative tumor patients suffering from advanced head and neck cancer benefited from this novel therapeutic modality. The gas plasma-induced biological effects of reactive oxygen and nitrogen species (ROS/RNS) generated in the plasma gas phase result in oxidation-induced lethal damage to tumor cells. Objectives: This study aimed to verify these anti-tumor effects of gas plasma exposure on urinary bladder cancer. Methods: 2D cell culture models, 3D tumor spheroids, 3D vascularized tumors grown on the chicken chorion-allantois-membrane (CAM) in ovo, and patient-derived primary cancer tissue gas plasma-treated ex vivo were used. Results: Gas plasma treatment led to oxidation, growth retardation, motility inhibition, and cell death in 2D and 3D tumor models. A marked decline in tumor growth was also observed in the tumors grown in ovo. In addition, results of gas plasma treatment on primary urothelial carcinoma tissues ex vivo highlighted the selective tumor-toxic effects as non-malignant tissue exposed to gas plasma was less affected. Whole-transcriptome gene expression analysis revealed downregulation of tumor-promoting fibroblast growth factor receptor 3 (FGFR3) accompanied by upregulation of apoptosis-inducing factor 2 (AIFm2), which plays a central role in caspase-independent cell death signaling. Conclusion: Gas plasma treatment induced cytotoxicity in patient-derived cancer tissue and slowed tumor growth in an organoid model of urinary bladder carcinoma, along with less severe effects in non-malignant tissues. Studies on the potential clinical benefits of this local and safe ROS therapy are awaited.
- ItemxCT (SLC7A11) expression confers intrinsic resistance to physical plasma treatment in tumor cells(Amsterdam [u.a.] : Elsevier, 2020) Bekeschus, Sander; Eisenmann, Sebastian; Sagwal, Sanjeev Kumar; Bodnar, Yana; Moritz, Juliane; Poschkamp, Broder; Stoffels, Ingo; Emmert, Steffen; Madesh, Muniswamy; Weltmann, Klaus-Dieter; von Woedtke, Thomas; Gandhirajan, Rajesh KumarCold physical plasma is a partially ionized gas investigated as a new anticancer tool in selectively targeting cancer cells in monotherapy or in combination with therapeutic agents. Here, we investigated the intrinsic resistance mechanisms of tumor cells towards physical plasma treatment. When analyzing the dose-response relationship to cold plasma-derived oxidants in 11 human cancer cell lines, we identified four 'resistant' and seven 'sensitive' cell lines. We observed stable intracellular glutathione levels following plasma treatment only in the 'resistant' cell lines indicative of altered antioxidant mechanisms. Assessment of proteins involved in GSH metabolism revealed cystine-glutamate antiporter xCT (SLC7A11) to be significantly more abundant in the 'resistant' cell lines as compared to 'sensitive' cell lines. This decisive role of xCT was confirmed by pharmacological and genetic inhibition, followed by cold physical plasma treatment. Finally, microscopy analysis of ex vivo plasma-treated human melanoma punch biopsies suggested a correlation between apoptosis and basal xCT protein abundance. Taken together, our results demonstrate that xCT holds the potential as a biomarker predicting the sensitivity of tumor cells towards plasma treatment.
- ItemCan the effect of cold physical plasma-derived oxidants be transported via thiol group oxidation?(Amsterdam [u.a.] : Elsevier, 2019) Heusler, Thea; Bruno, Giuliana; Bekeschus, Sander; Lackmann, Jan-Wilm; Woedtke, Thomas von; Wende, KristianPurpose: Intra- and intercellular redox-signaling processes where found responsible in various physiological and pathological processes with cellular thiol groups as important signal transducers. Using cold atmospheric plasma (CAP), a similar oxidation pattern of thiol groups can be achieved. Hence, it must be clarified which role extracellular thiol groups play in mediating CAP effects and whether or not the effects of short-lived reactive species can be preserved in a molecule like cysteine. Methods: Physiological buffer solutions containing the amino acid cysteine were treated by an MHz argon plasma jet with molecular gas admixtures (kINPen) and transferred to cultured human keratinocytes. Cell proliferation, migratory activity, and metabolism were investigated. High-resolution mass spectrometry was used to estimate the impact of plasma generated species on thiol groups. Results: While treated physiologic cysteine concentrations showed no impact on cell behavior, artificially high concentrations decreased proliferation, migration and lactate secretion. GSH levels inside cells were stabilized. Conclusion: Extracellular thiol groups scavenge plasma-generated species and form a multitude of covalent modifications. Unexpectedly, human keratinocytes show only small functional consequences for treated physiologic cysteine concentrations. Results for high concentrated cysteine solutions indicate an improved cytostatic/cytotoxic impact by plasma treatment suggesting a potential application as a “preserving agent” of the chemical energy of plasma-derived species. © 2019 The Authors
- ItemGas plasma-spurred wound healing is accompanied by regulation of focal adhesion, matrix remodeling, and tissue oxygenation(Amsterdam [u.a.] : Elsevier, 2021) Schmidt, Anke; Liebelt, Grit; Nießner, Felix; von Woedtke, Thomas; Bekeschus, SanderIn response to injury, efficient migration of skin cells to rapidly close the wound and restore barrier function requires a range of coordinated processes in cell spreading and migration. Gas plasma technology produces therapeutic reactive species that promote skin regeneration by driving proliferation and angiogenesis. However, the underlying molecular mechanisms regulating gas plasma-aided cell adhesion and matrix remodeling essential for wound closure remain elusive. Here, we combined in vitro analyses in primary dermal fibroblasts isolated from murine skin with in vivo studies in a murine wound model to demonstrate that gas plasma treatment changed phosphorylation of signaling molecules such as focal adhesion kinase and paxillin α in adhesion-associated complexes. In addition to cell spreading and migration, gas plasma exposure affected cell surface adhesion receptors (e.g., integrinα5β1, syndecan 4), structural proteins (e.g., vinculin, talin, actin), and transcription of genes associated with differentiation markers of fibroblasts-to-myofibroblasts and epithelial-to-mesenchymal transition, cellular protrusions, fibronectin fibrillogenesis, matrix metabolism, and matrix metalloproteinase activity. Finally, we documented that gas plasma exposure increased tissue oxygenation and skin perfusion during ROS-driven wound healing. Altogether, these results provide critical insights into the molecular machinery of gas plasma-assisted wound healing mechanisms.
- ItemPlatelets are key in cold physical plasma-facilitated blood coagulation in mice(Amsterdam [u.a.] : Elsevier, 2017) Bekeschus, Sander; Brüggemeier, Janik; Hackbarth, Christine; Woedtke, Thomas von; Partecke, Lars-Ivo; van der Linde, JuliaPurpose: Surgical interventions inevitably lead to destruction of blood vessels. This is especially dangerous in anticoagulated patients. Electrocauterization is a frequently used technique to seal incised tissue. However, leading to a superficial layer of necrotic tissue, the treated area evolves a high vulnerability to contact, making it prone to detachment. As a result, dangerous postoperative bleeding may occur. Cold physical plasma was previously suggested as a pro-coagulant treatment method. It mainly acts by expelling a delicate mixture of oxidants. We therefore tested the suitability of an atmospheric pressure plasma jet (kINPen MED) as a new medical device for sufficient blood coagulation in a murine model of liver incision. Methods: Plasma treatment of murine blood ex vivo induced sufficient coagula. This effect did not affect any tested parameter of plasmatic coagulation cascade, suggesting the mechanism to be related to cellular coagulation. Indeed, isolated platelets were significantly activated following exposure to plasma, although this effect was less pronounced in whole blood. To analyze the biological effect of plasma-on blood coagulation in vivo, mice were anticoagulated (clopidogrel inhibiting cellular and rivaroxaban inhibiting plasmatic hemostasis) or received vehicle only. Afterwards, a partial resection of the left lateral liver lobe was performed. The quantification of the blood loss after liver incision followed by treatment with kINPen MED plasma or electrocauterization revealed a similar and significant hemostatic performance in native and rivaroxaban but not clopidogrel-treated animals compared to argon gas-treated controls. In contrast to electrocauterization, kINPen MED plasma treatment did not cause necrotic cell layers. Conclusion: Our results propose a prime importance of platelets in cold physical plasma-mediated hemostasis and suggest a clinical benefit of kINPen MED plasma treatment as coagulation device in liver surgery.
- ItemTargeting malignant melanoma with physical plasmas(Amsterdam [u.a.] : Elsevier, 2018) Pasqual-Melo, Gabriella; Gandhirajan, Rajesh Kumar; Stoffels, Ingo; Bekeschus, SanderMelanoma is the deadliest form of cutaneous neoplasia. With a five-year survival rate of only 5–19%, metastatic melanoma presents severe challenges in clinical therapies. In addition, palliation is often problematic due to large numbers of fast growing metastasis. This calls for new therapeutic avenues targeting highly aggressive melanoma in palliative patients. One recently suggested innovative approach for eradication of topical tumor lesions is the application of cold physical plasma. This partially ionized gas emits a cocktail of reactive oxygen and nitrogen species (ROS/RNS). ROS/RNS have been shown to be a double-edged sword in fueling cancer growth at low doses but abrogating it at higher doses. The ROS/RNS output of plasma devices is tunable, and many studies have successfully decreased cancer cell growth in vitro and tumor burden in vivo. In general, increasing numbers of clinical trials suggest combination therapies to outperform monotherapies with regard to prognosis in patients. This review describes current challenges in melanoma treatment and highlights the concept of plasma therapy in experimental studies performed in melanoma research. Future perspectives are given that combine the usage of physical plasma with e.g. chemotherapy, immunotherapy, and ionizing radiation in melanoma medical oncology.
- ItemMedical gas plasma-stimulated wound healing: Evidence and mechanisms(Amsterdam [u.a.] : Elsevier, 2021) Bekeschus, Sander; von Woedtke, Thomas; Emmert, Steffen; Schmidt, AnkeDefective wound healing poses a significant burden on patients and healthcare systems. In recent years, a novel reactive oxygen and nitrogen species (ROS/RNS) based therapy has received considerable attention among dermatologists for targeting chronic wounds. The multifaceted ROS/RNS are generated using gas plasma technology, a partially ionized gas operated at body temperature. This review integrates preclinical and clinical evidence into a set of working hypotheses mainly based on redox processes aiding in elucidating the mechanisms of action and optimizing gas plasmas for therapeutic purposes. These hypotheses include increased wound tissue oxygenation and vascularization, amplified apoptosis of senescent cells, redox signaling, and augmented microbial inactivation. Instead of a dominant role of a single effector, it is proposed that all mechanisms act in concert in gas plasma-stimulated healing, rationalizing the use of this technology in therapy-resistant wounds. Finally, addressable current challenges and future concepts are outlined, which may further promote the clinical utilization, efficacy, and safety of gas plasma technology in wound care in the future.
- ItemMedical gas plasma promotes blood coagulation via platelet activation(Amsterdam [u.a.] : Elsevier, 2021) Bekeschus, Sander; Poschkamp, Broder; van der Linde, JuliaMajor blood loss still is a risk factor during surgery. Electrocauterization often is used for necrotizing the tissue and thereby halts bleeding (hemostasis). However, the carbonized tissue is prone to falling off, putting patients at risk of severe side effects, such as dangerous internal bleeding many hours after surgery. We have developed a medical gas plasma jet technology as an alternative to electrocauterization and investigated its hemostatic (blood clotting) effects and mechanisms of action using whole human blood. The gas plasma efficiently coagulated anticoagulated donor blood, which resulted from the local lysis of red blood cells (hemolysis). Image cytometry further showed enhanced platelet aggregation. Gas plasmas release reactive oxygen species (ROS), but neither scavenging of long-lived ROS nor addition of chemically-generated ROS were able to abrogate or recapitulate the gas plasma effect, respectively. However, platelet activation was markedly impaired in platelet-rich plasma when compared to gas plasma-treated whole blood that moreover contained significant amounts of hemoglobin indicative of red blood cell lysis (hemolysis). Finally, incubation of whole blood with concentration-matched hemolysates phenocopied the gas plasmas-mediated platelet activation. These results will spur the translation of plasma systems for hemolysis into clinical practice.