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Plasma-derived reactive species shape a differentiation profile in human monocytes
Background: Monocyte-derived macrophages are key regulators and producers of reactive oxygen and nitrogen species (ROS/RNS). Pre-clinical and clinical studies suggest that cold physical plasma may be beneficial in the treatment of inflammatory conditions via the release of ROS/RNS. However, it is unknown how plasma treatment affects monocytes and their differentiation profile. Methods: Naïve or phorbol-12-myristate-13-acetate (PMA)-pulsed THP-1 monocytes were exposed to cold physical plasma. The cells were analyzed regarding their metabolic activity as well as flow cytometry (analysis of viability, oxidation, surface marker expression and cytokine secretion) and high content imaging (quantitative analysis of morphology. Results: The plasma treatment affected THP-1 metabolisms, viability, and morphology. Furthermore, a significant modulation CD55, CD69, CD271 surface-expression and increase of inflammatory IL1β, IL6, IL8, and MCP1 secretion was observed upon plasma treatment. Distinct phenotypical changes in THP-1 cells arguing for a differentiation profile were validated in primary monocytes from donor blood. As a functional outcome, plasma-treated monocytes decreased the viability of co-cultured melanoma cells to a greater extent than their non-treated counterparts. Conclusions: Our results suggest plasma-derived ROS/RNS shaped a differentiation profile in human monocytes as evidenced by their increased inflammatory profile (surface marker and cytokines) as well as functional outcome (tumor toxicity). © 2019 by the authors.
Mineral-Based Coating of Plasma-Treated Carbon Fibre Rovings for Carbon Concrete Composites with Enhanced Mechanical Performance
Surfaces of carbon fibre roving were modified by means of a low temperature plasma treatment to improve their bonding with mineral fines; the latter serving as an inorganic fibre coating for the improved mechanical performance of carbon reinforcement in concrete matrices. Variation of the plasma conditions, such as gas composition and treatment time, was accomplished to establish polar groups on the carbon fibres prior to contact with the suspension of mineral particles in water. Subsequently, the rovings were implemented in a fine concrete matrix and their pull-out performance was assessed. Every plasma treatment resulted in increased pull-out forces in comparison to the reference samples without plasma treatment, indicating a better bonding between the mineral coating material and the carbon fibres. Significant differences were found, depending on gas composition and treatment time. Microscopic investigations showed that the samples with the highest pull-out force exhibited carbon fibre surfaces with the largest areas of hydration products grown on them. Additionally, the coating material ingresses into the multifilament roving in these specimens, leading to better force transfer between individual carbon filaments and between the entire roving and surrounding matrix, thus explaining the superior mechanical performance of the specimens containing appropriately plasma-treated carbon roving.
Plasma-activation of larger liquid volumes by an inductively-limited discharge for antimicrobial purposes
A new configuration of a discharge chamber and power source for the treatment of up to 1 L of liquid is presented. A leakage transformer, energizing two metal electrodes positioned above the liquid, limits the discharge current inductively by utilizing the weak magnetic coupling between the primary and secondary coils. No additional means to avoid arcing (electric short-circuiting), e.g., dielectric barriers or resistors, are needed. By using this technique, exceeding the breakdown voltage leads to the formation of transient spark discharges, producing non-thermal plasma (NTP). These discharges effected significant changes in the properties of the treated liquids (distilled water, physiological saline solution, and tap water). Considerable concentrations of nitrite and nitrate were detected after the plasma treatment. Furthermore, all tested liquids gained strong antibacterial efficacy which was shown by inactivating suspended Escherichia coli and Staphylococcus aureus. Plasma-treated tap water had the strongest effect, which is shown for the first time. Additionally, the pH-value of tap water did not decrease during the plasma treatment, and its conductivity increased less than for the other tested liquids. © 2019 by the authors.
Physical plasma-treated saline promotes an immunogenic phenotype in CT26 colon cancer cells in vitro and in vivo
Metastatic colorectal cancer is the fourth most common cause of cancer death. Current options in palliation such as hyperthermic intraperitoneal chemotherapy (HIPEC) present severe side effects. Recent research efforts suggested the therapeutic use of oxidant-enriched liquid using cold physical plasma. To investigate a clinically accepted treatment regimen, we assessed the antitumor capacity of plasma-treated saline solution. In response to such liquid, CT26 murine colon cancer cells were readily oxidized and showed cell growth with subsequent apoptosis, cell cycle arrest, and upregulation of immunogenic cell death (ICD) markers in vitro. This was accompanied by marked morphological changes with re-arrangement of actin fibers and reduced motility. Induction of an epithelial-to-mesenchymal transition phenotype was not observed. Key results were confirmed in MC38 colon and PDA6606 pancreatic cancer cells. Compared to plasma-treated saline, hydrogen peroxide was inferiorly toxic in 3D tumor spheroids but of similar efficacy in 2D models. In vivo, plasma-treated saline decreased tumor burden in Balb/C mice. This was concomitant with elevated numbers of intratumoral macrophages and increased T cell activation following incubation with CT26 cells ex vivo. Being a potential adjuvant for HIPEC therapy, our results suggest oxidizing saline solutions to inactivate colon cancer cells while potentially stimulating antitumor immune responses.
Making Sense of Complex Carbon and Metal/Carbon Systems by Secondary Electron Hyperspectral Imaging
Carbon and carbon/metal systems with a multitude of functionalities are ubiquitous in new technologies but understanding on the nanoscale remains elusive due to their affinity for interaction with their environment and limitations in available characterization techniques. This paper introduces a spectroscopic technique and demonstrates its capacity to reveal chemical variations of carbon. The effectiveness of this approach is validated experimentally through spatially averaging spectroscopic techniques and using Monte Carlo modeling. Characteristic spectra shapes and peak positions for varying contributions of sp2-like or sp3-like bond types and amorphous hydrogenated carbon are reported under circumstances which might be observed on highly oriented pyrolytic graphite (HOPG) surfaces as a result of air or electron beam exposure. The spectral features identified above are then used to identify the different forms of carbon present within the metallic films deposited from reactive organometallic inks. While spectra for metals is obtained in dedicated surface science instrumentation, the complex relations between carbon and metal species is only revealed by secondary electron (SE) spectroscopy and SE hyperspectral imaging obtained in a state-of-the-art scanning electron microscope (SEM). This work reveals the inhomogeneous incorporation of carbon on the nanoscale but also uncovers a link between local orientation of metallic components and carbon form.
Activation of murine immune cells upon co-culture with plasma-treated B16F10 melanoma cells
Recent advances in melanoma therapy increased median survival in patients. However, death rates are still high, motivating the need of novel avenues in melanoma treatment. Cold physical plasma expels a cocktail of reactive species that have been suggested for cancer treatment. High species concentrations can be used to exploit apoptotic redox signaling pathways in tumor cells. Moreover, an immune-stimulatory role of plasma treatment, as well as plasma-killed tumor cells, was recently proposed, but studies using primary immune cells are scarce. To this end, we investigated the role of plasma-treated murine B16F10 melanoma cells in modulating murine immune cells' activation and marker profile. Melanoma cells exposed to plasma showed reduced metabolic and migratory activity, and an increased release of danger signals (ATP, CXCL1). This led to an altered cytokine profile with interleukin-1β (IL-1β) and CCL4 being significantly increased in plasma-treated mono- and co-cultures with immune cells. In T cells, plasma-treated melanoma cells induced extracellular signal-regulated Kinase (ERK) phosphorylation and increased CD28 expression, suggesting their activation. In monocytes, CD115 expression was elevated as a marker for activation. In summary, here we provide proof of concept that plasma-killed tumor cells are recognized immunologically, and that plasma exerts stimulating effects on immune cells alone. © 2019 by the authors.
Non-thermal plasma-treated solution demonstrates antitumor activity against pancreatic cancer cells in vitro and in vivo
Pancreatic cancer is associated with a high mortality rate. In advanced stage, patients often experience peritoneal carcinomatosis. Using a syngeneic murine pancreatic cancer cell tumor model, the effect of non-thermal plasma (NTP) on peritoneal metastatic lesions was studied. NTP generates reactive species of several kinds which have been proven to be of relevance in cancer. In vitro, exposure to both plasma and plasma-treated solution significantly decreased cell viability and proliferation of 6606PDA cancer cells, whereas mouse fibroblasts were less affected. Repeated intraperitoneal treatment of NTP-conditioned medium decreased tumor growth in vivo as determined by magnetic resonance imaging, leading to reduced tumor mass and improved median survival (61 vs 52 days; p < 0.024). Tumor nodes treated by NTP-conditioned medium demonstrated large areas of apoptosis with strongly inhibited cell proliferation. Contemporaneously, no systemic effects were found. Apoptosis was neither present in the liver nor in the gut. Also, the concentration of different cytokines in splenocytes or blood plasma as well as the distribution of various hematological parameters remained unchanged following treatment with NTP-conditioned medium. These results suggest an anticancer role of NTP-treated solutions with little to no systemic side effects being present, making NTP-treated solutions a potential complementary therapeutic option for advanced tumors.
Deposition of Antimicrobial Copper-Rich Coatings on Polymers by Atmospheric Pressure Jet Plasmas
Inanimate surfaces serve as a permanent reservoir for infectious microorganisms, which is a growing problem in areas in everyday life. Coating of surfaces with inorganic antimicrobials, such as copper, can contribute to reduce the adherence and growth of microorganisms. The use of a DC operated air plasma jet for the deposition of copper thin films on acrylonitrile butadiene styrene (ABS) substrates is reported. ABS is a widespread material used in consumer applications, including hospitals. The influence of gas flow rate and input current on thin film characteristics and its bactericidal effect have been studied. Results from X-ray photoelectron spectroscopy (XPS) and atomic force microscopy confirmed the presence of thin copper layers on plasma-exposed ABS and the formation of copper particles with a size in the range from 20 to 100 nm, respectively. The bactericidal properties of the copper-coated surfaces were tested against Staphylococcus aureus. A reduction in growth by 93% compared with the attachment of bacteria on untreated samples was observed for coverage of the surface with 7 at. % copper.
Cold argon plasma as adjuvant tumour therapy on progressive head and neck cancer: A preclinical study
Investigating cold argon plasma (CAP) for medical applications is a rapidly growing, innovative field of research. The controllable supply of reactive oxygen and nitrogen species through CAP has the potential for utilization in tumour treatment. Maxillofacial surgery is limited if tumours grow on vital structures such as the arteria carotis. Here CAP could be considered as an option for adjuvant intraoperative tumour therapy especially in the case of squamous cell carcinoma of the head and neck. Further preclinical research is necessary to investigate the efficacy of this technology for future clinical applications in cancer treatment. Initially, a variety of in vitro assays was performed on two cell lines that served as surrogate for the squamous cell carcinoma (SCC) and healthy tissue, respectively. Cell viability, motility and the activation of apoptosis in SCC cells (HNO97) was compared with those in normal HaCaT keratinocytes. In addition, induction of apoptosis in ex vivo CAP treated human tissue biopsies of patients with tumours of the head and neck was monitored and compared to healthy control tissue of the same patient. In response to CAP treatment, normal HaCaT keratinocytes differed significantly from their malignant counterpart HNO97 cells in cell motility only whereas cell viability remained similar. Moreover, CAP treatment of tumour tissue induced more apoptotic cells than in healthy tissue that was accompanied by elevated extracellular cytochrome c levels. This study promotes a future role of CAP as an adjuvant intraoperative tumour therapy option in the treatment of head and neck cancer. Moreover, patient-derived tissue explants complement in vitro examinations in a meaningful way to reflect an antitumoral role of CAP. © 2019 by the authors.
Physical plasma-triggered ROS induces tumor cell death upon cleavage of HSP90 chaperone
HSP90 is a ubiquitously expressed molecular chaperone implicated in the correct folding and maturation of a plethora of proteins including protein kinases and transcription factors. While disruption of chaperone activity was associated with augmented cancer cell death and decreased tumor growth both in vitro and in vivo, the regulation of HSP90 is not clearly understood. Here we report that treatment of cancer cells with cold physical plasma, an emerging and less aggressive tumor therapy, resulted in ROS generation which subsequently triggered the cleavage of HSP90. Notably, cleavage of HSP90 was followed by the degradation of PKD2, a crucial regulator of tumor growth and angiogenesis. Pre-sensitization of cancer cells with subliminal doses of PU-H71, an HSP90 inhibitor currently under clinical evaluation, followed by treatment with cold-plasma, synergistically and negatively impacted on the viability of cancer cells. Taken together, cold-plasma can be used in conjunction with pharmacologic treatment in order to target the expression and activity of HSP90 and the downstream client proteins implicated in various cancer cell capabilities.