The molecular and physiological consequences of cold plasma treatment in murine skin and its barrier function

Cold plasma enhances the generation of reactive oxygen species and the uptake of nanoparticles in cancer cells

Objectives

Cold plasma, which is a rich source of reactive oxygen species (ROS) and also generates them when it comes into contact with cells, is being investigated for its potential to target cancer cells. ROS are crucial in causing tumor damage and are divided into long- and short-term species. Among them, the analysis of short-lived radicals such as hydroxyl radicals (HO⋅) is much more important because they are primarily responsible for biological damage and can also generate long-lived radicals. Moreover, selecting nanoparticles (NPs) to treat cancer is important; however, what matters most is how well the NPs are absorbed by the tumor. To minimize adverse effects, the challenge of many cancer treatments is selectivity. Cold plasma and gold (GNPs) were used in this study to target melanoma cells, and increase ROS production and GNP absorption.

Methods

The research involved testing efficiency with an MTT assay on melanoma cells and selectivity on healthy fibroblast cells. Flow cytometry measured apoptosis rates, whereas a chemical dosimeter measured the amount of free radicals generated in each treatment group. The average gold content absorbed in each cell was measured with inductively coupled plasma optical emission spectroscopy (ICP-OES) with and without cold plasma therapy.

Results

The findings demonstrated that while cold plasma caused cancer cells to undergo apoptosis, healthy cells remained unaffected. This effect was greatest when GNPs were used. The presence of cold plasma led to the significant production of HO⋅. Additionally, it was observed that cold plasma enhanced the uptake of GNPs in cancer cells while having no effect on healthy cells.

Conclusion

The findings of this study suggest that the approach of combining GNPs and cold plasma could offer an optimized targeted therapeutic option for addressing the challenges associated with melanoma management.

Radical formation in skin and preclinical characterization of a novel medical plasma device for dermatology after single application

Cold atmospheric plasma (CAP) enables painless tissue treatment by producing reactive species including excited molecules and charged particles and is of great interest for medical applications. Medical CAP sources work in contact with air at ambient pressure, resulting in the generation of substantial amounts of reactive oxygen and nitrogen radicals. These radicals have a significant influence on cellular biochemistry, are crucial components of the immune system, and play a central role in wound therapy. CAP has a variety of applications, with a particular emphasis on tissue treatment in dermatology. It eradicates microorganisms by preventing biofilm formation so that wounds can be effectively disinfected and treated antiseptically. Using both in vitro and ex vivo methods, a comprehensive preclinical assessment of a novel battery-operated cold plasma handheld device with a reusable, and autoclavable glass cylinder was performed. The objectives were to evaluate the potential impact of single CAP application on radical formation with and without wound dressing, by directly measuring radicals in skin, to investigate the influence of CAP application on antimicrobial activity and cytotoxicity in vitro, and to assess skin tolerance ex vivo. The direct effect of CAP on the formation of radicals in the skin after plasma application at different levels with and without wound dressing was demonstrated quantitatively for the first time using electron paramagnetic resonance spectroscopy. Free radicals were measured in the skin as a function of the duration of CAP treatment. Furthermore, it was found that an alginate or wound plaster dressing does not significantly inhibit radical formation in skin compared to application without a dressing. In vitro and ex vivo data showed no cytotoxic potential with simultaneous efficacy against bacteria strains and no risk of temperature rise, pH change, skin barrier or DNA damage. These results show a high potential for wound healing applications in vivo.

Enhancing the efficacy of low doses of N-acetyl-L-cysteine in mitigating CCl4-induced hepatotoxicity in animal model using physical cold plasma

Liver diseases have become widespread especially due to various factors of modern life. Although the effect of N-acetyl-L-cysteine (NAC) is investigated in the recovery of liver damage, gas plasma therapy can be identified as a promising candidate. Our study aimed to enhance the effectiveness of ineffective doses of NAC in stopping CCl4-induced hepatotoxicity in rats by physical cold plasma. The plasma-treated NAC (PTN) structural changes were investigated through FTIR and LCMS/MS analysis. It was observed that the PTN consists of various chemical bioproducts with different molecular weights. We investigated an ineffective dose of NAC and its parallel effect through the administration of PTN on liver and kidney morphology and several biochemical factors including ALT, AST, and ALP. Additionally, we examined oxidative stress, antioxidant parameters, and glutathione (GSH) levels. Results showed that PTN exhibited greater antioxidant properties and increased GSH levels, contributing to its therapeutic effects. Also, the antioxidant enzymes and oxidative stress activities improved after receiving PTN. It also enhanced histological parameters, although various damages were detected in both liver and kidney tissues after CCl4 injection, PTN remarkably prevented the tissue changes caused by CCl4. PTN could protect against liver damage even at a very low dose of NAC, acting as a prophylactic drug with a high margin of safety for hepatotoxicity.

Epilipidomics reveals lipid fatty acid and headgroup modification in gas plasma-oxidized biomembranes

Lipids, possessing unsaturated fatty acid chains and polar regions with nucleophilic heteroatoms, represent suitable oxidation targets for autologous and heterologous reactive species. Lipid peroxidation products (LPPs) are highly heterogeneous, including hydroperoxides, alkenals, chlorination, or glycation. Accordingly, delineation of lipid targets, species type, resulting products, and oxidation level remains challenging. To this end, liposomal biomimetic models incorporating a phosphatidylcholine, -ethanolamine, and a sphingomyelin were used to deconvolute effects on a single lipid scale to predict potential modification product outcomes. To introduce oxidative modifications, gas plasma technology, a powerful pro-oxidant tool to promote LPP formation by forming highly abundant reactive species in the gas and liquid phases, was employed to liposomes. The plasma parameters (gas type/combination) were modified to modulate the resulting species-profile and LPP formation by enriching specific reactive species types over others. HR-LC-MS (Münzel and et al., 2017) [2] was employed for LPP identification. Moreover, the heavy oxygen isotope 18O was used to trace O2-incorporation into LPPs, providing first information on the plasma-mediated lipid peroxidation mechanism. We found that combination of lipid class and gas composition predetermined the type of attack: admixture of O2 to the plasma and the presence of nitrogen atoms with free electrons in the molecule lead to chlorination of the amide bond and headgroup. Here, atomic oxygen driven formation of hypochlorite is the major reactive species. In contrast, POPC yields mainly to LPPs with oxidation of the oleic acid tail, especially truncations, epoxidation, and hydroperoxide formation. Here, singlet oxygen is assumingly the major driver. 18O labelling revealed that gas phase derived reactive species are dominantly incorporated into the LPPs, supporting previous findings on gas-liquid interface chemistry. In summary, we here provided the first insights into gas plasma-mediated lipid peroxidation, which, employed in more complex cell and tissue models, may support identifying mechanisms of actions in plasma medicine.

Optimization of the Treatment of Squamous Cell Carcinoma Cells by Combining Photodynamic Therapy with Cold Atmospheric Plasma

Actinic keratosis (AK) is characterized by a reddish or occasionally skin-toned rough patch on sun-damaged skin, and it is regarded as a precursor to squamous cell carcinoma (SCC). Photodynamic therapy (PDT), utilizing 5-aminolevulinic acid (ALA) along with red light, is a recognized treatment option for AK that is limited by the penetration depth of light and the distribution of the photosensitizer into the skin. Cold atmospheric plasma (CAP) is a partially ionized gas with permeability-enhancing and anti-cancer properties. This study analyzed, in vitro, whether a combined treatment of CAP and ALA-PDT may improve the efficacy of the treatment. In addition, the effect of the application sequence of ALA and CAP was investigated using in vitro assays and the molecular characterization of human oral SCC cell lines (SCC-9, SCC-15, SCC-111), human cutaneous SCC cell lines (SCL-1, SCL-2, A431), and normal human epidermal keratinocytes (HEKn). The anti-tumor effect was determined by migration, invasion, and apoptosis assays and supported the improved efficacy of ALA-PDT in combination with CAP. However, the application sequence ALA-CAP-red light seems to be more efficacious than CAP-ALA-red light, which is probably due to increased intracellular ROS levels when ALA is applied first, followed by CAP and red light treatment. Furthermore, the expression of apoptosis- and senescence-related molecules (caspase-3, -6, -9, p16INK4a, p21CIP1) was increased, and different genes of the junctional network (ZO-1, CX31, CLDN1, CTNNB1) were induced after the combined treatment of CAP plus ALA-PDT. HEKn, however, were much less affected than SCC cells. Overall, the results show that CAP may improve the anti-tumor effects of conventional ALA-PDT on SCC cells. Whether this combined application is successful in treating AK in vivo has to be carefully examined in follow-up studies.

Hydroxytyrosol permeability comparisons and strategies to improve hydroxytyrosol stability in formulations

There has been a growing interest in hydroxytyrosol (HT) due to its powerful antioxidant and free-radical scavenging properties when added to formulations such as pharmaceuticals and cosmetics. To study the stability and transdermal properties of hydrogels and creams (HT-based formulations), a high-performance liquid chromatography method was developed for determining HT. In the Franz diffusion cell system, both hydrogel and cream show a rapid and similar penetration profile through the Bama miniature pig skin. However, the Strat-M® membrane exhibits slightly lower permeability and is selective to different formulations; that is, the cream has a permeability value of 10.69%, while the hydrogel has a value of 5.27%. The dynamics parameters from the permeation assays indicate that the model using the Strat-M® membrane can be used as a screening tool to evaluate the skin uptake and permeation efficacy of different formulations. Adding 3-O-ethyl-L-ascorbic acid to HT-based formulations can effectively prevent discoloration under prolonged high-temperature storage, while combining multiple antioxidants delays degradation most effectively. This study provides novel ideas for functional formulation optimization to enhance the realism and reproducibility of cosmetic products containing HT and provides scientific evidence for the production, packaging, shelf life, storage, and transportation of products.

Umbilical therapy for promoting transdermal delivery of topical formulations: Enhanced effect and underlying mechanism

Umbilical paste therapy is a promising method to promote transdermal drug delivery of topical formulations. This work investigated the effect and mechanism of transdermal drug delivery through the umbilical skin. The transdermal permeation studies showed the phenomenon of higher cumulative penetration and faster penetration rates for drug through the umbilical skin compared with non-umbilical skin, namely umbilical pro-permeability. This special transdermal permeability of drugs is influenced by their molecular weight, logP value, ability to form hydrogen bonds, and molecular volume. The underlying mechanism of umbilical pro-permeability was elucidated from unique structure and regulation the effect of drugs on microcirculation in the umbilical skin. Mechanistic studies revealed that this phenomenon was not only associated with the structural and physiological properties of the skin but also to the interactions between drugs and different skin layers. The umbilical pro-permeation is attributed to the thinner stratum corneum layer, differences in stratum corneum lipid composition and keratin structure, and lower levels of intercellular tight junction proteins in the viable epidermis and dermis layer of the skin. Our research indicated that umbilical paste therapy enhanced the transdermal delivery and absorption of drugs by stimulating local blood flow through mast cell activation. Surprisingly, skin temperature modulation and calcitonin gene-related peptide and substance P levels did not appear to significantly affect this process. In conclusion, umbilical drug administration, as a straightforward and non-invasive approach to enhance transdermal drug delivery, presents novel concepts for continued investigation and practical implementation of transdermal drug delivery systems.

Gas plasmas technology: from biomolecule redox research to medical therapy

Physical plasma is one consequence of gas ionization, i.e. its dissociation of electrons and ions. If operated in ambient air containing oxygen and nitrogen, its high reactivity produces various reactive oxygen and nitrogen species (RONS) simultaneously. Technology leap innovations in the early 2010s facilitated the generation of gas plasmas aimed at clinics and operated at body temperature, enabling their potential use in medicine. In parallel, their high potency as antimicrobial agents was systematically discovered. In combination with first successful clinical trials, this led in 2013 to the clinical approval of first medical gas plasma devices in Europe for promoting the healing of chronic and infected wounds and ulcers in dermatology. While since then, thousands of patients have benefited from medical gas plasma therapy, only the appreciation of the critical role of gas plasma-derived RONS led to unraveling first fragments of the mechanistic basics of gas plasma-mediated biomedical effects. However, drawing the complete picture of effectors and effects is still challenging. This is because gas plasma-produced RONS not only show a great variety of dozens of types but also each of them having distinct spatio-temporal concentration profiles due to their specific half-lives and reactivity with other types of RONS as well as different types of (bio) molecules they can react with. However, this makes gas plasmas fascinating and highly versatile tools for biomolecular redox research, especially considering that the technical capacity of increasing and decreasing individual RONS types holds excellent potential for tailoring gas plasmas toward specific applications and disease therapies.

Effects of cold atmospheric-pressure plasma in combination with doxorubicin drug against breast cancer cells in vitro and invivo

Cold atmospheric plasma (CAP) has been suggested for medical applications that can be applied indirectly through plasma-activated medium (PAM) and recently it has been introduced as an innovative therapeutic approach for all cancer types. Studies have exhibited that ROS/RNS are key factors in CAP-dependent apoptosis; nevertheless, ROS/RNS stability are weak. Combination therapy is considered an effective strategy to overcome these problems. In the present research, we revealed that the combination of CAP and doxorubicin (DOX) significantly induces the apoptosis of breast cancer cells both in vitro and in vivo. Our results indicated that both Ar and He/O2 CAP treatment as well as DOX drug alone reduced cell growth. CAP/PAM treatment in combination with DOX induced apoptosis in MCF-7 breast cancer cells and 4T1-implanted BALB/c mice, resulting in a significant increase in antitumor activity. The apoptotic effects of CAP-DOX on MCF-7 cells were inferred from altered expression of BAX and cleaved-caspase-3 which mechanistically take place through the mitochondrial pathway mediated by Bcl-2 family members. Besides, the BAX/BCL-2 ratio is significantly higher in the simultaneous treatment of CAP and DOX. This ratio was equal to 2.82 ± 0.24, 2.54 ± 0.30, and 11.27 ± 0.31 for treatment with DOX, He/O2 plasma, and combination treatment, respectively. Additionally, the tumor growth rate of He/O2-PAM + DOX and Ar-PAM + DOX treatments was significantly inhibited by PAM-injection, and the tumor growth rate of PAM alone or DOX alone was slightly reduced. It can be concluded that the effect of PAM + DOX may increase the anticancer activity and decrease the dose required for the chemotherapeutic treatment.

Exploring the potential of cold plasma therapy in treating bacterial infections in veterinary medicine: opportunities and challenges

Cold plasma therapy is a novel approach that has shown significant promise in treating bacterial infections in veterinary medicine. Cold plasma possesses the potential to eliminate various bacteria, including those that are resistant to antibiotics, which renders it a desirable substitute for traditional antibiotics. Furthermore, it can enhance the immune system and facilitate the process of wound healing. However, there are some challenges associated with the use of cold plasma in veterinary medicine, such as achieving consistent and uniform exposure to the affected area, determining optimal treatment conditions, and evaluating the long-term impact on animal health. This paper explores the potential of cold plasma therapy in veterinary medicine for managing bacterial diseases, including respiratory infections, skin infections, and wound infections such as Clostridium botulinum, Clostridium perfringens, Bacillus cereus, and Bacillus subtilis. It also shows the opportunities and challenges associated with its use. In conclusion, the paper highlights the promising potential of utilizing cold plasma in veterinary medicine. However, to gain a comprehensive understanding of its benefits and limitations, further research is required. Future studies should concentrate on refining treatment protocols and assessing the long-term effects of cold plasma therapy on bacterial infections and the overall health of animals.

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.

Modeling Gas Plasma-Tissue Interactions in 3D Collagen-Based Hydrogel Cancer Cell Cultures

Gas plasma jet technology was recently identified as a potential adjuvant in the fight against cancer. Here, the partial ionization of gas yields the local formation of an exceptional variety of highly reactive oxygen (ROS) and nitrogen (RNS) species, which are considered the main actors of plasma-induced antitumor effects. Yet, fundamental knowledge in preclinical plasma research relies on the predominant use of two-dimensional cell culture systems, despite causing significant shifts in redox chemistries that largely limit translational relevance. So far, the intricacy of studying complex plasma–tissue interactions causes substantial knowledge gaps concerning the key mechanisms and therapeutical limitations of plasma treatment in a living organism. Identifying physiologically relevant yet simplified tissue models is vital to address such questions. In our study, a side-by-side comparison of conventional and pre-established hydrogel models emphasized this discrepancy, revealing a marked difference in plasma-induced toxicity related to species distribution dynamics. Chemically embedded, fluorescent reporters were further used to characterize reactive species’ fingerprints in hydrogels compared to liquids. In addition, a thirteen cell-line screening outlined the widespread applicability of the approach while indicating the need to optimize growth conditions dependent on the cell line investigated. Overall, our study presents important implications for the implementation of clinically relevant tissue culture models in preclinical plasma medicine in the future.

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

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

Influence of a transient spark plasma discharge on producing high molecular masses of chemical products from L-cysteine

Cold atmospheric pressure plasmas are considered a forthcoming method in many research areas. Plasma modification of biomolecules has received much attention in addition to plasma-treated biomaterials. Hence, in this work, we operated a transient spark plasma (TSP) discharge to study its effect on the L-cysteine chemical structure. the TSP was configured in a pin-to-ring electrode arrangement and flowed by Ar gas. We also investigated the effect of two chemicals; dimethyl sulfoxide (DMSO) and hydrogen peroxide (H₂O₂) by the bubbling method to show how they can change the creation of new chemical bioproducts. Ultraviolet-Visible absorption spectroscopy, Fourier transform infrared spectroscopy and Liquid chromatography-mass spectroscopy were used to investigate any changes in chemical bonds of cysteine structure and to depict the generation of new biomolecules. Based on the displayed results plasma-generated reactive species had a great role in the chemical structure of the cysteine. Entering DMSO and H₂O₂ into the plasma caused the creation of new products and the heaviest biomolecule was produced by the simultaneous addition of DMSO and H₂O₂. The results also predicted that some chemical products and amino acids with a higher value molecular masse produced from the polymerization process of cysteine solution. The strong oxidation process is responsible for the heavy chemical compounds.

Short- and long-term polystyrene nano- and microplastic exposure promotes oxidative stress and divergently affects skin cell architecture and Wnt/beta-catenin signaling

Nano- and microplastic particles (NMP) are strong environmental contaminants affecting marine ecosystems and human health. The negligible use of biodegradable plastics and the lack of knowledge about plastic uptake, accumulation, and functional consequences led us to investigate the short- and long-term effects in freshly isolated skin cells from mice. Using fluorescent NMP of several sizes (200 nm to 6 µm), efficient cellular uptake was observed, causing, however, only minor acute toxicity as metabolic activity and apoptosis data suggested, albeit changes in intracellular reactive species and thiol levels were observed. The internalized NMP induced an altered expression of various targets of the nuclear factor-2-related transcription factor 2 pathway and were accompanied by changed antioxidant and oxidative stress signaling responses, as suggested by altered heme oxygenase 1 and glutathione peroxide 2 levels. A highly increased beta-catenin expression under acute but not chronic NMP exposure was concomitant with a strong translocation from membrane to the nucleus and subsequent transcription activation of Wnt signaling target genes after both single-dose and chronic long-term NMP exposure. Moreover, fibroblast-to-myofibroblast transdifferentiation accompanied by an increase of α smooth muscle actin and collagen expression was observed. Together with several NMP-induced changes in junctional and adherence protein expression, our study for the first time elucidates the acute and chronic effects of NMP of different sizes in primary skin cells' signaling and functional biology, contributing to a better understanding of nano- and microplastic to health risks in higher vertebrates.

Possible Synergies of Nanomaterial-Assisted Tissue Regeneration in Plasma Medicine: Mechanisms and Safety Concerns

Cold atmospheric plasma and nanomedicine originally emerged as individual domains, but are increasingly applied in combination with each other. Most research is performed in the context of cancer treatment, with only little focus yet on the possible synergies. Many questions remain on the potential of this promising hybrid technology, particularly regarding regenerative medicine and tissue engineering. In this perspective article, we therefore start from the fundamental mechanisms in the individual technologies, in order to envision possible synergies for wound healing and tissue recovery, as well as research strategies to discover and optimize them. Among these strategies, we demonstrate how cold plasmas and nanomaterials can enhance each other's strengths and overcome each other's limitations. The parallels with cancer research, biotechnology and plasma surface modification further serve as inspiration for the envisioned synergies in tissue regeneration. The discovery and optimization of synergies may also be realized based on a profound understanding of the underlying redox- and field-related biological processes. Finally, we emphasize the toxicity concerns in plasma and nanomedicine, which may be partly remediated by their combination, but also partly amplified. A widespread use of standardized protocols and materials is therefore strongly recommended, to ensure both a fast and safe clinical implementation.

Uncertainty Quantification and Sensitivity Analysis for the Electrical Impedance Spectroscopy of Changes to Intercellular Junctions Induced by Cold Atmospheric Plasma

The influence of pertinent parameters of a Cole-Cole model in the impedimetric assessment of cell-monolayers was investigated with respect to the significance of their individual contribution. The analysis enables conclusions on characteristics, such as intercellular junctions. Especially cold atmospheric plasma (CAP) has been proven to influence intercellular junctions which may become a key factor in CAP-related biological effects. Therefore, the response of rat liver epithelial cells (WB-F344) and their malignant counterpart (WB-ras) was studied by electrical impedance spectroscopy (EIS). Cell monolayers before and after CAP treatment were analyzed. An uncertainty quantification (UQ) of Cole parameters revealed the frequency cut-off point between low and high frequency resistances. A sensitivity analysis (SA) showed that the Cole parameters, R₀ and α were the most sensitive, while R_inf and τ were the least sensitive. The temporal development of major Cole parameters indicates that CAP induced reversible changes in intercellular junctions, but not significant changes in membrane permeability. Sustained changes of τ suggested that long-lived ROS, such as H₂O₂, might play an important role. The proposed analysis confirms that an inherent advantage of EIS is the real time observation for CAP-induced changes on intercellular junctions, with a label-free and in situ method manner.

The potential of gas plasma technology for targeting breast cancer

Despite therapeutic improvements in recent years, breast cancer remains an often fatal disease. In addition, breast cancer ulceration may occur during late stages, further complicating therapeutic or palliative interventions. In the past decade, a novel technology received significant attention in the medical field: gas plasma. This topical treatment relies on the partial ionization of gases that simultaneously produce a plethora of reactive oxygen and nitrogen species (ROS/RNS). Such local ROS/RNS overload inactivates tumour cells in a non-necrotic manner and was recently identified to induce immunogenic cancer cell death (ICD). ICD promotes dendritic cell maturation and amplifies antitumour immunity capable of targeting breast cancer metastases. Gas plasma technology was also shown to provide additive toxicity in combination with radio and chemotherapy and re-sensitized drug-resistant breast cancer cells. This work outlines the assets of gas plasma technology as a novel tool for targeting breast cancer by summarizing the action of plasma devices, the roles of ROS, signalling pathways, modes of cell death, combination therapies and immunological consequences of gas plasma exposure in breast cancer cells in vitro, in vivo, and in patient-derived microtissues ex vivo.

Plasma Dermatology: Skin Therapy Using Cold Atmospheric Plasma

Cold atmospheric plasma-based plasma medicine has been expanding the diversity of its specialties. As an emerging branch, plasma dermatology takes advantage of the beneficial complexity of plasma constituents (e.g., reactive oxygen and nitrogen species, UV photons, and electromagnetic emission), technical versatility (e.g., direct irradiation and indirect aqueous treatment), and practical feasibility (e.g., hand-held compact device and clinician-friendly operation). The objective of this comprehensive review is to summarize recent advances in the CAP-dominated skin therapy by broadly covering three aspects. We start with plasma optimisation of intact skin, detailing the effect of CAP on skin lipids, cells, histology, and blood circulation. We then conduct a clinically oriented and thorough dissection of CAP treatment of various skin diseases, focusing on the wound healing, inflammatory disorders, infectious conditions, parasitic infestations, cutaneous malignancies, and alopecia. Finally, we conclude with a brief analysis on the safety aspect of CAP treatment and a proposal on how to mitigate the potential risks. This comprehensive review endeavors to serve as a mini textbook for clinical dermatologists and a practical manual for plasma biotechnologists. Our collective goal is to consolidate plasma dermatology’s lead in modern personalized medicine.

Low-intensity cold atmospheric plasma reduces wrinkles on photoaged skin through hormetic induction of extracellular matrix protein expression in dermal fibroblasts

BACKGROUND

Recent evidence indicates that cold atmospheric plasma (CAP) can upregulate the production of extracellular matrix (ECM) proteins in dermal fibroblasts and enhance transdermal drug delivery when applied at a low intensity.

OBJECTIVES

The aim of this study was to evaluate the effect of low-intensity CAP (LICAP) on photoaging-induced wrinkles in an animal model and the expression profiles of ECM proteins in human dermal fibroblasts.

METHODS

Each group was subjected to photoaging induction and allocated to therapy (LICAP, topical polylactic acid (PLA), or both). The wrinkles were evaluated via visual inspection, quantitative analysis, and histology. The expression of collagen I/III and fibronectin was assessed using reverse transcription-quantitative polymerase chain reaction, western blot analysis, and immunofluorescence. The amount of aqueous reactive species produced by LICAP using helium and argon gas was also measured.

RESULTS

Wrinkles significantly decreased in all treatment groups compared to those in the untreated control. The differences remained significant for at least 4 weeks. Dermal collagen density increased following LICAP and PLA application. LICAP demonstrated a hormetic effect on ECM protein expression in human dermal fibroblasts. The production of reactive species increased, showing a biphasic pattern, with an initial linear phase and a slow saturation phase. The initial linearity was sustained for a longer time in the helium plasma (~60 s) than in the argon plasma (~15 s).

CONCLUSION

LICAP appears to be a novel treatment option for wrinkles on the photodamaged skin. This treatment effect seems to be related to its hormetic effect on dermal ECM production.

Therapeutic Effects of Cold Atmospheric Plasma on Solid Tumor

Cancer is a devastating disease, and there is no particularly effective treatment at present. Recently, a new treatment, cold atmospheric plasma (CAP), has been proposed. At present, CAP is confirmed to have selective killing effect on tumor by many studies in vitro and in vivo. A targeted literature search was carried out on the study of cold atmospheric plasma. Through analysis and screening, a narrative review approach was selected to describe therapeutic effects of cold atmospheric plasma on solid tumor. According to the recent studies on plasma, some hypothetical therapeutic schemes of CAP are proposed in this paper. The killing mechanism of CAP on solid tumor is expounded in terms of the selectivity of CAP to tumor, the effects of CAP on cells, tumor microenvironment (TME) and immune system. CAP has many effects on solid tumors, and these effects are dose-dependent. The effects of optimal doses of CAP on solid tumors include killing tumor cells, inhibiting non-malignant cells and ECM in TME, affecting the communication between tumor cells, and inducing immunogenic death of tumor cells. In addition, several promising research directions of CAP are proposed in this review, which provide guidance for future research.

Periodic Exposure of Plasma-Activated Medium Alters Fibroblast Cellular Homoeostasis

Excess amounts of redox stress and failure to regulate homeostatic levels of reactive species are associated with several skin pathophysiologic conditions. Nonmalignant cells are assumed to cope better with higher reactive oxygen and nitrogen species (RONS) levels. However, the effect of periodic stress on this balance has not been investigated in fibroblasts in the field of plasma medicine. In this study, we aimed to investigate intrinsic changes with respect to cellular proliferation, cell cycle, and ability to neutralize the redox stress inside fibroblast cells following periodic redox stress in vitro. Soft jet plasma with air as feeding gas was used to generate plasma-activated medium (PAM) for inducing redox stress conditions. We assessed cellular viability, energetics, and cell cycle machinery under oxidative stress conditions at weeks 3, 6, 9, and 12. Fibroblasts retained their usual physiological properties until 6 weeks. Fibroblasts failed to overcome the redox stress induced by periodic PAM exposure after 6 weeks, indicating its threshold potential. Periodic stress above the threshold level led to alterations in fibroblast cellular processes. These include consistent increases in apoptosis, while RONS accumulation and cell cycle arrest were observed at the final stages. Currently, the use of NTP in clinical settings is limited due to a lack of knowledge about fibroblasts’ behavior in wound healing, scar formation, and other fibrotic disorders. Understanding fibroblasts’ physiology could help to utilize nonthermal plasma in redox-related skin diseases. Furthermore, these results provide new information about the threshold capacity of fibroblasts and an insight into the adaptation mechanism against periodic oxidative stress conditions in fibroblasts.

Conductivity augments ROS and RNS delivery and tumor toxicity of an argon plasma jet

Gas plasma jet technology was recently identified as a potential adjuvant in the palliation of cancer patients. However, a practical point raised is if higher therapeutic efficacy is achieved with the gas plasma applied in direct contact to the tumor tissue (conducting) or during treatment with the remote cloud of reactive oxygen and nitrogen species (ROS/RNS) being expelled. In a bedside-to-bench study, this clinical question was translated into studying these two distinct treatment modalities using a three-dimensional tumor cell-matrix-hydrogel assay with subsequent quantitative confocal imaging. Z-resolved fluorescence analysis of two cancer cell lines revealed greater toxicity of the conducting mode. This result was re-iterated in the growth analysis of vascularized tumor tissue cultured on chicken embryos' CAM using in ovo bioluminescence imaging. Furthermore, for conducting compared to free mode, optical emission spectroscopy revealed stronger RNS signal lines in the gas phase, while both ROS/RNS deposition in the liquid was drastically exacerbated in the conducting mode. Altogether, our results are vital in understanding the importance of standardized treatment distances on the therapeutic efficacy of gas plasma exposure in clinical oncology and will help to give critical implications for clinicians involved in plasma onco-therapy in the future.

The current and advanced therapeutic modalities for wound healing management

Ever-increasing demands on improving efficiencies of wound healing procedures are a strong driving force for the development of replacement approaches. This review focuses on wound healing management from the point of formation to the point of healing procedures. The most important usual healing modality with key characteristic is explained and their limitations are discussed. Novel interesting approaches are presented with a concentration of the unique features and action mechanisms. Special attention is paid to gas plasma and nanotechnology impact on wound healing management from fundamental processes to beneficial outcomes. Challenges and opportunities for the future trend that combined common protocols and emerging technologies are discussed.

Combining Nanotechnology and Gas Plasma as an Emerging Platform for Cancer Therapy: Mechanism and Therapeutic Implication

Nanomedicine and plasma medicine are innovative and multidisciplinary research fields aiming to employ nanotechnology and gas plasma to improve health-related treatments. Especially cancer treatment has been in the focus of both approaches because clinical response rates with traditional methods that remain improvable for many types of tumor entities. Here, we discuss the recent progress of nanotechnology and gas plasma independently as well as in the concomitant modality of nanoplasma as multimodal platforms with unique capabilities for addressing various therapeutic issues in oncological research. The main features, delivery vehicles, and nexus between reactivity and therapeutic outcomes of nanoparticles and the processes, efficacy, and mechanisms of gas plasma are examined. Especially that the unique feature of gas plasma technology, the local and temporally controlled deposition of a plethora of reactive oxygen, and nitrogen species released simultaneously might be a suitable additive treatment to the use of systemic nanotechnology therapy approaches. Finally, we focus on the convergence of plasma and nanotechnology to provide a suitable strategy that may lead to the required therapeutic outcomes.

Gas Plasma-Augmented Wound Healing in Animal Models and Veterinary Medicine

The loss of skin integrity is inevitable in life. Wound healing is a necessary sequence of events to reconstitute the body’s integrity against potentially harmful environmental agents and restore homeostasis. Attempts to improve cutaneous wound healing are therefore as old as humanity itself. Furthermore, nowadays, targeting defective wound healing is of utmost importance in an aging society with underlying diseases such as diabetes and vascular insufficiencies being on the rise. Because chronic wounds’ etiology and specific traits differ, there is widespread polypragmasia in targeting non-healing conditions. Reactive oxygen and nitrogen species (ROS/RNS) are an overarching theme accompanying wound healing and its biological stages. ROS are signaling agents generated by phagocytes to inactivate pathogens. Although ROS/RNS’s central role in the biology of wound healing has long been appreciated, it was only until the recent decade that these agents were explicitly used to target defective wound healing using gas plasma technology. Gas plasma is a physical state of matter and is a partially ionized gas operated at body temperature which generates a plethora of ROS/RNS simultaneously in a spatiotemporally controlled manner. Animal models of wound healing have been vital in driving the development of these wound healing-promoting technologies, and this review summarizes the current knowledge and identifies open ends derived from in vivo wound models under gas plasma therapy. While gas plasma-assisted wound healing in humans has become well established in Europe, veterinary medicine is an emerging field with great potential to improve the lives of suffering animals.

Prospective, comparative clinical pilot study of cold atmospheric plasma device in the treatment of atopic dermatitis

Cold atmospheric plasma generates free radicals through the ionization of air at room temperature. Its effect and safety profile as a treatment modality for atopic dermatitis lesions have not been evaluated prospectively enough. We aimed to investigate the effect and safety of cold atmospheric plasma in patients with atopic dermatitis with a prospective pilot study. Cold atmospheric plasma treatment or sham control treatment were applied respectively in randomly assigned and symmetric skin lesions. Three treatment sessions were performed at weeks 0, 1, and 2. Clinical severity indices were assessed at weeks 0, 1, 2, and 4 after treatment. Additionally, the microbial characteristics of the lesions before and after treatments were analyzed. We included 22 patients with mild to moderate atopic dermatitis presented with symmetric lesions. We found that cold atmospheric plasma can alleviate the clinical severity of atopic dermatitis. Modified atopic dermatitis antecubital severity and eczema area and severity index score were significantly decreased in the treated group. Furthermore, scoring of atopic dermatitis score and pruritic visual analog scales significantly improved. Microbiome analysis revealed significantly reduced proportion of Staphylococcus aureus in the treated group. Cold atmospheric plasma can significantly improve mild and moderate atopic dermatitis without safety issues.

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.

Atmospheric Pressure Plasma Irradiation Facilitates Transdermal Permeability of Aniline Blue on Porcine Skin and the Cellular Permeability of Keratinocytes with the Production of Nitric Oxide

The transdermal delivery system of nutrients, cosmetics, and drugs is particularly attractive for painless, noninvasive delivery and sustainable release. Recently, atmospheric pressure plasma techniques have been of great interest to improve the drug absorption rate in transdermal delivery. Currently, plasma-mediated changes in the lipid composition of the stratum corneum are considered a possible mechanism to increase transdermal permeability. Nevertheless, its molecular and cellular mechanisms in transdermal delivery have been largely confined and still veiled. Herein, we present the effects of cold plasma on transdermal transmission on porcine skin and the cellular permeability of keratinocytes and further demonstrate the production of nitric oxide from keratinocytes. Consequently, argon plasma irradiation for 60 s resulted in 2.5-fold higher transdermal absorption of aniline blue dye on porcine skin compared to the nontreated control. In addition, the plasma-treated keratinocytes showed an increased transmission of high-molecular-weight molecules (70 and 150 kDa) with the production of nitric oxide. Therefore, these findings suggest a promoting effect of low-temperature plasma on transdermal absorption, even for high-molecular-weight molecules. Moreover, plasma-induced nitric oxide from keratinocytes is likely to regulate transdermal permeability in the epidermal layer.

Tumor cytotoxicity and immunogenicity of a novel V-jet neon plasma source compared to the kINPen

Recent research indicated the potential of cold physical plasma in cancer therapy. The plethora of plasma-derived reactive oxygen and nitrogen species (ROS/RNS) mediate diverse antitumor effects after eliciting oxidative stress in cancer cells. We aimed at exploiting this principle using a newly designed dual-jet neon plasma source (^Vjet) to treat colorectal cancer cells. A treatment time-dependent ROS/RNS generation induced oxidation, growth retardation, and cell death within 3D tumor spheroids were found. In TUM-CAM, a semi in vivo model, the ^Vjet markedly reduced vascularized tumors' growth, but an increase of tumor cell immunogenicity or uptake by dendritic cells was not observed. By comparison, the argon-driven single jet kINPen, known to mediate anticancer effects in vitro, in vivo, and in patients, generated less ROS/RNS and terminal cell death in spheroids. In the TUM-CAM model, however, the kINPen was equivalently effective and induced a stronger expression of immunogenic cancer cell death (ICD) markers, leading to increased phagocytosis of kINPen but not ^Vjet plasma-treated tumor cells by dendritic cells. Moreover, the ^Vjet was characterized according to the requirements of the DIN-SPEC 91315. Our results highlight the plasma device-specific action on cancer cells for evaluating optimal discharges for plasma cancer treatment.

Gas plasma-spurred wound healing is accompanied by regulation of focal adhesion, matrix remodeling, and tissue oxygenation

In 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.