Effects of cold atmospheric plasma (CAP) on ß-defensins, inflammatory cytokines, and apoptosis-related molecules in keratinocytes in vitro and in vivo

Cold atmospheric pressure plasma for treatment of chronic wounds: drug or medical device?

OBJECTIVE

The use of cold atmospheric pressure plasma (CAPP) as a new therapeutic option to aid the healing of chronic wounds appears promising. Currently, uncertainty exists regarding their classification as medical device or medical drug. Because the classification of CAPP has medical, legal, and economic consequences as well as implications for the level of preclinical and clinical testing, the correct classification is not an academic exercise, but an ethical need.

METHOD

A multidisciplinary team of physicians, surgeons, pharmacists, physicists and lawyers has analysed the physical and technical characteristics as well as legal conditions of the biological action of CAPP.

RESULTS

It was concluded that the mode of action of the locally generated CAPP, with its main active components being different radicals, is pharmacological and not physical in nature.

CONCLUSION

Depending on the intended use, CAPP should be classified as a drug, which is generated by use of a medical device directly at the point of therapeutic application.

Cold atmospheric pressure plasmas exhibit antimicrobial properties against critical bacteria and yeast species

OBJECTIVE

Cold atmospheric pressure plasmas (CAPPs) have been used to sterilise implant materials and other thermally unstable medical products and to modify chemical surfaces. This study investigates the antimicrobial effect of the gas and input power used to generate CAPPs on microorganisms causing skin infections, such as Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Malassezia pachydermatis.

METHOD

Microorganisms were cultivated on Mueller Hinton 2 (MH2) agar plates. CAPP treatment was performed using the Plasma BLASTER MEF. To investigate the antimicrobial effects the following CAPP parameters were varied: the gas used, input power, as well as number of treatments and treatment time.

RESULTS

The antimicrobial efficacy of the CAPPs was found to increase with increasing input power and treatment time (or cycles). Furthermore the plasma generated from nitrogen is more effective than from air.

CONCLUSION

The study showed that CAPPs demonstrate strong bactericidal and fungicidal properties in vitro. The selective application of CAPPs for the treatment of wound infections may offer a promising supplementary tool alongside current therapies.

Short exposure to cold atmospheric plasma induces senescence in human skin fibroblasts and adipose mesenchymal stromal cells

Cold Atmospheric Plasma (CAP) is a novel promising tool developed in several biomedical applications such as cutaneous wound healing or skin cancer. Nevertheless, in vitro studies are lacking regarding to CAP effects on cellular actors involved in healthy skin healing and regarding to the mechanism of action. In this study, we investigated the effect of a 3 minutes exposure to CAP-Helium on human dermal fibroblasts and Adipose-derived Stromal Cells (ASC) obtained from the same tissue sample. We observed that CAP treatment did not induce cell death but lead to proliferation arrest with an increase in p53/p21 and DNA damages. Interestingly we showed that CAP treated dermal fibroblasts and ASC developed a senescence phenotype with p16 expression, characteristic morphological changes, Senescence-Associated β-galactosidase expression and the secretion of pro-inflammatory cytokines defined as the Senescence-Associated Secretory Phenotype (SASP). Moreover this senescence phenotype is associated with a glycolytic switch and an increase in mitochondria content. Despite this senescence phenotype, cells kept in vitro functional properties like differentiation potential and immunomodulatory effects. To conclude, we demonstrated that two main skin cellular actors are resistant to cell death but develop a senescence phenotype while maintaining some functional characteristics after 3 minutes of CAP-Helium treatment in vitro.

Non-thermal atmospheric pressure plasma is an excellent tool to activate proliferation in various mesoderm-derived human adult stem cells

Adult stem cells are capable of self-renewal and differentiation into specific cell types in tissues and have high potential for stem cell therapy. Mesenchymal and hematopoietic stem cells are easily attainable from the human body and have become applicable tools for adult stem cell therapy. However, there are still technical barriers for the application of mesenchymal and hematopoietic stem cells for therapy, such as the small number of cell populations, high risk of contamination, and loss of their stemness properties in vitro. In our previous study, we showed that non-thermal atmospheric pressure plasma (NTAPP) promoted the proliferation of adipose tissue-derived stem cells (ASCs) by 1.6-fold on average, while maintaining their stemness. Here, we examined the feasibility of NTAPP as a tool to activate the proliferation of mesenchymal and hematopoietic stem cells in vitro without affecting their stem cell characteristics. NTAPP increased the proliferation of bone marrow-derived stem cells (BM-MSCs) and hematopoietic stem cells (HSCs) by 1.8- and 2-fold, respectively, when compared to that of untreated cells. As observed in ASCs, NTAPP exposure also activated the expression of stem cell-specific surface markers, CD44 and CD105, by 5-fold in BM-MSCs, when compared to that in unexposed control cells in a low glucose medium with a low concentration of basic fibroblast growth factor (b-FGF). In addition, NTAPP exposure highly augmented the mRNA expression of well-known pluripotent genes for stemness, such as Oct4, Sox2, and Nanog in ASCs and BM-MSCs when compared to that in unexposed control cells. When cell cycle progression was examined, the G1-S shift was accelerated, and expression of PCNA was increased in NTAPP-exposed ASCs when compared to that in untreated control cells, suggesting that NTAPP activated G1-S transition. Taken together, these results demonstrated that NTAPP activated the proliferation of various mesodermal-derived human adult stem cells by accelerating the G1-S transition while maintaining their pluripotency and stemness, strongly suggesting that NTAPP can be an efficient tool for expanding the population of various adult stem cells in vitro for medical applications.

Nrf2 signaling and inflammation are key events in physical plasma-spurred wound healing

Wound healing is strongly associated with the presence of a balanced content of reactive species in which oxygen-dependent, redox-sensitive signaling represents an essential step in the healing cascade. Numerous studies have demonstrated that cold physical plasma supports wound healing due to its ability to deliver a beneficial mixture of reactive species directly to the cells.

Methods: We described a preclinical proof-of-principle-concept of cold plasma use in a dermal, full-thickness wound model in immunocompetent SKH1 mice. Quantitative PCR, Western blot analysis, immunohistochemistry and immunofluorescence were perfomed to evaluate the expression and cellular translocation of essential targets of Nrf2 and p53 signaling as well as immunomodulatory and angiogenetic factors. Apoptosis and proliferation were detected using TUNEL assay and Ki67 staining, respectively. Cytokine levels in serum were measured using bead-based multiplex cytokine analysis. Epidermal keratinocytes and dermal fibroblasts were isolated from mouse skin to perform functional knockdown experiments. Intravital fluorescence analysis was used to illustrate and quantified microvascular features.

Results: Plasma exerted significant effects on wound healing in mice, including the promotion of granulation and reepithelialization as a consequence of the migration of skin cells, the balance of antioxidant and inflammatory response, and the early induction of macrophage and neutrophil recruitment to the wound sites. Moreover, through an early and local plasma-induced p53 inhibition with a concomitant stimulation of proliferation, the upregulation of angiogenetic factors, and an increased outgrowth of new vessels, our findings explain why dermal skin repair is accelerated. The cellular redox homeostasis was maintained and cells were defended from damage by a strong modulation of the nuclear E2-related factor (Nrf2) pathway and redox-sensitive p53 signaling.

Conclusions: Although acute wound healing is non-problematic, the pathways highlighted that mainly the activation of Nrf2 signaling is a promising strategy for the clinical use of cold plasma in chronic wound healing.

Treatment of Infected Wounds in the Age of Antimicrobial Resistance: Contemporary Alternative Therapeutic Options

As antibiotic resistance increases and antimicrobial options diminish, there is a pressing need to identify and develop new and/or alternative (non-antimicrobial-based) wound therapies. The authors describe the implications of antibiotic resistance on their current wound treatment paradigms and review the most promising non-antibiotic-based antimicrobial agents currently in research and development, with a focus on preclinical and human studies of therapeutic bacteriophages, antimicrobial peptides, cold plasma treatment, photodynamic therapy, honey, silver, and bioelectric dressings.

Effect of cold plasma on periodontal wound healing-an in vitro study

OBJECTIVES

Cold atmospheric plasma (CAP), a room temperate ionized gas, seems to be a possible way to enhance tissue recovery. An in vitro study was conducted to investigate the influence of medical CAP on the regenerative capacity of human periodontal ligament (PDL) cells.

MATERIAL AND METHODS

Human PDL cells were subjected to CAP at various intensities, distances, and durations. The effects of CAP on a number of specific markers were studied at transcriptional level using real-time PCR. Additionally, an in vitro wound healing assay was applied to PDL cell monolayers either in the presence or absence of CAP by using JuLI™ Br Live Cell Analyzer and software. Finally, cell viability of CAP-treated cells was analyzed by an XTT assay.

RESULTS

CAP treatment enhanced significantly the expression of the cytokines tumor necrosis factor (TNF)α, cyclooxygenase (COX)2, interleukin (IL)-1β, IL-6, IL-8, collagen (COL)1α, and matrix metalloproteinase (MMP)1, as well as the proliferation markers Ki67 and proliferating cell nuclear antigen (PCNA), but downregulated apoptotic markers Apaf1 and p53. Additionally, the in vitro wound healing rate was significantly enhanced after CAP application. Moreover, CAP treatment resulted in a significantly increased cell viability in the XTT assay.

CONCLUSION

This in vitro study shows that CAP has regulatable effects on markers of periodontal wound healing thereby underlining the potential use of CAP as a benefit treatment strategy.

CLINICAL RELEVANCE

Our study demonstrates the application of CAP in the treatment of oral pathologies suggesting a promising future treatment approach.

Non-thermal atmospheric pressure plasma-induced IL-8 expression is regulated via intracellular K+ loss and subsequent ERK activation in human keratinocyte HaCaT cells

Non-thermal atmospheric pressure plasma (NTAPP) has recently emerged as a novel medical therapy for skin wounds. Interleukin-8 (IL-8) is thought to play a critical role in wound healing. NTAPP irradiation has been reported to promote production of IL-8; however, the mechanism is not fully understood. The aim of this study was to elucidate the underlying mechanism of NTAPP-induced IL-8 expression in human keratinocyte HaCaT cells. NTAPP irradiation of HaCaT cells increased IL-8 mRNA expression in an irradiation time-dependent manner. Although hydrogen peroxide (H₂O₂) was generated in culture medium irradiated with NTAPP, treatment of HaCaT cells with H₂O₂ itself failed to induce the expression. In addition, we found that NTAPP irradiation of HaCaT cells decreased intracellular K⁺ levels. High intracellular K⁺ concentrations suppressed NTAPP-induced IL-8 mRNA expression, and the K⁺ ionophore valinomycin (Val) enhanced the induction of IL-8 mRNA. Moreover, NTAPP stimulated activation of ERK MAP kinase and the ERK inhibitor prevented NTAPP-induced IL-8 mRNA expression. NTAPP-induced ERK activation was inhibited in the presence of high concentrations of extracellular K⁺ and enhanced in the presence of Val. Taken together, these findings suggest that NTAPP irradiation stimulates intracellular K⁺ loss and subsequent ERK activation, leading to the induction of IL-8 expression.

A cold plasma jet accelerates wound healing in a murine model of full-thickness skin wounds

Cold plasma has been successfully applied in several fields of medicine that require, for example, pathogen inactivation, implant functionalization or alteration of cellular activity. Previous studies have provided evidence that plasma supports the healing of wounds owing to its beneficial mixtures of reactive species and modulation of inflammation in cells and tissues. To investigate the wound healing activity of an atmospheric pressure plasma jet in vivo, we examined the cold plasma's efficacy on dermal regeneration in a murine model of dermal full-thickness ear wound. Over 14 days, female mice received daily plasma treatment. Quantitative analysis by transmitted light microscopy demonstrated a significantly accelerated wound re-epithelialization at days 3-9 in comparison with untreated controls. In vitro, cold plasma altered keratinocyte and fibroblast migration, while both cell types showed significant stimulation resulting in accelerated closure of gaps in scratch assays. This plasma effect correlated with the downregulation of the gap junctional protein connexin 43 which is thought to be important in the regulation of wound healing. In addition, plasma induced profound changes in adherence junctions and cytoskeletal dynamics as shown by downregulation of E-cadherin and several integrins as well as actin reorganization. Our results theorize cold plasma to be a beneficial treatment option supplementing existing wound therapies.

Cold atmospheric plasma (CAP) activates angiogenesis-related molecules in skin keratinocytes, fibroblasts and endothelial cells and improves wound angiogenesis in an autocrine and paracrine mode

BACKGROUND

Cold atmospheric plasma (CAP) emerged as a novel therapeutic field with applications developed for bacterial sterilization, wound healing and cancer treatment. For clinical implementation it is important to know how CAP works and which molecular changes occur after the CAP treatment. Vascularization is an important step during wound healing, however, the effects of CAP on wound angiogenesis are not well examined so far. Furthermore, it has not been investigated, whether CAP primarily affects endothelial cells directly or via paracrine mechanisms to modulate the vasculature.

OBJECTIVE

This study concentrates on the influence of CAP on angiogenesis-related molecules in human epidermal keratinocytes, dermal fibroblasts and endothelial cells.

METHODS

CAP was generated by the MicroPlaSter ß® plasma torch system and CAP effects on angiogenesis were determined in vitro and in vivo.

RESULTS

We observed that CAP significantly induces the expression of Artemin, EGF, EG-VEGF (PK1), Endothelin-1 (ET-1), FGF-2 (FGF basic), IL-8 (CXCL8) and uPA in keratinocytes and Angiogenin (ANG), Endostatin (Col18A1), MCP-1 (CCL2), MMP-9, TIMP-1, uPA and VEGF in fibroblasts. In addition, CAP activates the expression of Angiopoietin-2 (Ang-2), Angiostatin (PLG), Amphiregulin (AR), Endostatin, FGF-2 and angiogenic-involved receptor expression of FGF R1 and VEGF R1 in HUVEC endothelial cells. It was also demonstrated that supernatants collected from CAP activated fibroblasts and keratinocytes elevate tube formation by endothelial cells and FGF-2 appears to be an important pro-angiogenic factor that controls vascularization via paracrine mechanisms. Mouse experiments supplement that CAP promotes angiogenesis during wound healing in vivo.

CONCLUSIONS

Taken together, these results suggest that CAP modulates angiogenesis-involved factors via autocrine and paracrine mechanisms and may be used to affect angiogenesis during wound healing.

Basic Research in Plasma Medicine - A Throughput Approach from Liquids to Cells

In plasma medicine, ionized gases with temperatures close to that of vertebrate systems are applied to cells and tissues. Cold plasmas generate reactive species known to redox regulate biological processes in health and disease. Pre-clinical and clinical evidence points to beneficial effects of plasma treatment in the healing of chronic ulcer of the skin. Other emerging topics, such as plasma cancer treatment, are receiving increasing attention. Plasma medical research requires interdisciplinary expertise in physics, chemistry, and biomedicine. One goal of plasma research is to characterize plasma-treated cells in a variety of specific applications. This includes, for example, cell count and viability, cellular oxidation, mitochondrial activity, cytotoxicity and mode of cell death, cell cycle analysis, cell surface marker expression, and cytokine release. This study describes the essential equipment and workflows required for such research in plasma biomedicine. It describes the proper operation of an atmospheric pressure argon plasma jet, specifically monitoring its basic emission spectra and feed gas settings to modulate reactive species output. Using a high-precision xyz-table and computer software, the jet is hovered in millisecond-precision over the cavities of 96-well plates in micrometer-precision for maximal reproducibility. Downstream assays for liquid analysis of redox-active molecules are shown, and target cells are plasma-treated. Specifically, melanoma cells are analyzed in an efficient sequence of different consecutive assays but using the same cells: measurement of metabolic activity, total cell area, and surface marker expression of calreticulin, a molecule important for the immunogenic cell death of cancer cells. These assays retrieve content-rich biological information about plasma effects from a single plate. Altogether, this study describes the essential steps and protocols for plasma medical research.

Non-thermal atmospheric plasma ameliorates imiquimod-induced psoriasis-like skin inflammation in mice through inhibition of immune responses and up-regulation of PD-L1 expression

Plasma medicine is an emerging novel therapeutic field. It has been reported that plasma can kill bacteria, promote wound healing and induce apoptosis of tumor cells. However, the effects of plasma on immune cells and immune related skin diseases have not been well studied. In this study, we demonstrated that non-thermal atmospheric plasma (NTP) treatment could inhibit psoriasis-like skin inflammation in mice. NTP treatment in imiquimod-induced psoriasis-like mouse skin inhibited increases in epithelial cell thickness and expression of pro-inflammatory molecules compared to ones without the NTP treatment. In addition, differentiation of Th17 cells, an important cell type for pathogenesis of psoriasis, was inhibited in the NTP-treated mouse lymph nodes. It was also demonstrated that liquid type plasma (LTP), which is also known as indirect plasma, inhibited Th17 cell differentiation in vitro. Other in vitro experiments showed that LTP inhibited bone marrow-derived dendritic cell activation. Interestingly, LTP enhanced PD-L1 expression in HaCaT cells, suggesting that NTP may inhibit unwanted over-activation of T cells through increased PD-L1 expression. Taken together, these results suggest that NTP may be used in treatment of CD4+ T cell-mediated autoimmune diseases such as psoriasis.

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.

Cold atmospheric plasma restores tamoxifen sensitivity in resistant MCF-7 breast cancer cell

Cancer recurrence, which is frequently accompanied by chemotherapy, has been a challenge in cancer treatment. This study was carried out to examine the potential applications of the reactive oxygen species (ROS)-producing cold atmospheric plasma (CAP) to overcome the cancer cells' drug resistance, which has been emerging as an alternative therapeutic tool for cancer. For this, we developed a tamoxifen (Tam)-resistant MCF-7 (MCF-7/TamR) breast cancer cell model and examined the effect of CAP on the recovery of Tam sensitivity at the cellular and molecular level. The ROS level was increased 1.9-fold in CAP-treated MCF-7/TamR cells compared to the non-treated cell. CAP was proven to restore sensitivity by up to 50% for MCF-7/TamR cells against Tam after CAP treatment. The comparison of genome-wide expression between the acquisition of Tam resistance and CAP treatment identified 20 genes that commonly showed significant expression changes. Notably, all the genes except two have been oppositely dysregulated in the two cellular statuses, and the majority of them are known to contribute to the acquisition of Tam resistance. The protein expression of selected genes, MX1 and HOXC6, was recovered to that of their parental cell by CAP. Furthermore, the dysregulation of MX1 and HOXC6 in MCF-7/TamR alleviated the drug sensitivity recovery effect of CAP. Taken together, CAP inhibited the growth of Tam-resistant MCF-7 cancer cells and reset it to the Tam-sensitive status by restoring the expression of drug resistance-related genes. These findings may lend credence to CAP as an alternative or complementary tool in the treatment or prevention of Tam-resistant cancer.

Cold atmospheric plasma in orthopaedic and urologic tumor therapy

Cold atmospheric plasma (CAP) is a highly reactive ionized physical state thereby provoking divers biological effects. In medical applications, CAP treatment promotes wound healing, provokes immunostimulation, and is antiseptically active. Moreover, CAP interacts with antiproliferative mechanisms suggesting CAP treatment as a promising anticancer strategy. Here we review the current state of science concerning the so far investigated CAP effects on different cancer entities in orthopaedic and urologic oncology.

[Plasma medicine in dermatology: Mechanisms of action and clinical applications]

Plasma medicine has developed into an innovative field of research showing high potential. Since the establishment of cold atmospheric plasma, new, multifaceted medical treatment opportunities have become available. Within a short time a multidisciplinary special interest group of medical scientists, physicists, and biologists was created, aiming to understand plasma medicine and answer clinical as well as scientific questions. In dermatology, new horizons are being opened for wound healing, tissue regeneration, treatment of skin infections, and tumor therapy. A major task will be the introduction of plasma into clinical medicine and, simultaneously, the further investigation of the mechanisms of action of plasma at the cellular level. Only then can the safety of plasma treatment in patients be assured.

Clinical and Biological Principles of Cold Atmospheric Plasma Application in Skin Cancer

Plasma-based electrosurgical devices have long been employed for tissue coagulation, cutting, desiccation, and cauterizing. Despite their clinical benefits, these technologies involve tissue heating and their effects are primarily heat-mediated. Recently, there have been significant developments in cold atmospheric pressure plasma (CAP) science and engineering. New sources of CAP with well-controlled temperatures below 40 °C have been designed, permitting safe plasma application on animal and human bodies. In the last decade, a new innovative field, often referred to as plasma medicine, which combines plasma physics, life science, and clinical medicine has emerged. This field aims to exploit effects of mild plasma by controlling the interactions between plasma components (and other secondary species that can be formed from these components) with specific structural elements and functionalities of living cells. Recent studies showed that CAP can exert beneficial effects when applied selectively in certain pathologies with minimal toxicity to normal tissues. The rapid increase in new investigations and development of various devices for CAP application suggest early adoption of cold plasma as a new tool in the biomedical field. This review explores the latest major achievements in the field, focusing on the biological effects, mechanisms of action, and clinical evidence of CAP applications in areas such as skin disinfection, tissue regeneration, chronic wounds, and cancer treatment. This information may serve as a foundation for the design of future clinical trials to assess the efficacy and safety of CAP as an adjuvant therapy for skin cancer.

The repetitive use of non-thermal dielectric barrier discharge plasma boosts cutaneous microcirculatory effects

BACKGROUND

Non-thermal atmospheric plasma has proven its benefits in sterilization, cauterization and even in cancer reduction. Furthermore, physical plasma generated by dielectric barrier discharge (DBD) promotes wound healing in vivo and angiogenesis in vitro. Moreover, cutaneous blood flow and oxygen saturation can be improved in human skin. These effects are mostly explained by reactive oxygen species (ROS), but electric fields, currents and ultraviolet radiation may also have an impact on cells in the treated area. Usually, single session application is used. The aim of this study was to evaluate the effects of the repetitive use of cold atmospheric plasma (rCAP) on cutaneous microcirculation.

HYPOTHESIS

The repetitive use of non-thermal atmospheric plasma boosts cutaneous microcirculation effects.

METHODS

Microcirculatory data was assessed at a defined skin area of the radial forearm of 20 healthy volunteers (17 males, 3 females; mean age 39.1±14.8years; BMI 26.4±4.6kg/m(2)). Microcirculatory measurements were performed under standardized conditions using a combined laser Doppler and photospectrometry system. After baseline measurement, CAP was applied by a DBD plasma device for 90s and cutaneous microcirculation was assessed for 10min. Afterwards, a second session of CAP application was performed and microcirculation was measured for another 10min. Then, the third application was made and another 20min of microcirculatory parameters were assessed.

RESULTS

Tissue oxygen saturation and postcapillary venous filling pressure significantly increased after the first application and returned to baseline values within 10min after treatment. After the second and third applications, both parameters increased significantly vs. baseline until the end of the 40-minute measuring period. Cutaneous blood flow was significantly enhanced for 1min after the first application, with no significant differences found during the remainder of the observation period. The second application improved and prolonged the effect significantly until 7min and the third application until 13min.

CONCLUSION

These data indicate that the repetitive use of non-thermal atmospheric plasma boosts and prolongs cutaneous microcirculation and might therefore be a potential tool to promote wound healing.

Bactericidal Efficacy of Cold Plasma at Different Depths of Infected Root Canals In Vitro

Objectives:

Cold plasma (CP) has been shown to be effective even against multiresistant microorganisms. As previous investigations on the effect of CP in root canals showed promising results, the aim of the present study was to analyze the bactericidal efficacy of CP in different depths of infected dentin.

Methods:

32 standardized root canals of human mandibular premolars were infected with Enterococcus faecalis and incubated for one week. Specimens were randomly selected for one of four disinfection methods: control (5mL NaCl), 5mL chlorhexidine (CHX), CP alone (CP), and a combination of 5mL CHX and cold plasma (CHX+CP). CHX was ultrasonically activated for 30s, while cold plasma was used for 60s in the root canals. Dentin samples at depths of 300, 500 and 800 µm were obtained and diluted serially. Colony forming units (CFUs) were counted on agar plates after 24h of incubation.

Results:

The highest overall logarithmic reduction factors (RF) were obtained from CHX+CP (log RF 3.56 p<0.01; Mann-Whitney U test), followed by CP (log RF 3.27 p<0.01) and CHX alone (log RF 2.65 p<0.01) related to the control. All disinfection methods showed significantly lower CFU counts compared to the control group in 300 µm and 800 µm (both p<0.01, Kruskal-Wallis test).

Discussion:

The adjuvant use of CP might be beneficial in highly infected root canals to improved disinfection. However, the disinfection effect against Enterococcus faecalis of CP is comparable to ultrasonically activated CHX.

Improvement of cutaneous microcirculation by cold atmospheric plasma (CAP): Results of a controlled, prospective cohort study

BACKGROUND

Cold atmospheric plasma (CAP) has proven its benefits in the reduction of various bacteria and fungi in both in vitro and in vivo studies. Moreover, CAP generated by dielectric barrier discharge (DBD) promoted wound healing in vivo. Charged particles, chemically reactive species (such as O3, OH, H2O2, O, NxOy), ultraviolet radiation (UV-A and UV-B), strong oscillating electric fields as well as weak electric currents are produced by DBD operated in air. However, wound healing is a complex process, depending on nutrient and oxygen supply via cutaneous blood circulation. Therefore, this study examined the effects of CAP on cutaneous microcirculation in a prospective cohort setting.

HYPOTHESIS

Cold atmospheric plasma application enhances cutaneous microcirculation.

METHODS

Microcirculatory data of 20 healthy subjects (11 males, 9 females; mean age 35.2 ± 13.8 years; BMI 24.3 ± 3.1 kg/m(2)) were recorded continuously at a defined skin area at the radial forearm. Under standardized conditions, microcirculatory measurements were performed using a combined laser Doppler and photospectrometry system. After baseline measurement, CAP was applied by a DBD plasma device for 90 s to the same defined skin area of 22.5 cm(2). Immediately after the application cutaneous microcirculation was assessed for 30 min at the same site.

RESULTS

After CAP application, tissue oxygen saturation immediately increased by 24% (63.8 ± 13.8% from 51.4 ± 13.2% at baseline, p<0.001) and stayed significantly elevated for 8 min. Cutaneous blood flow increased by 73% (41.0 ± 31.2 AU from 23.7 ± 20.8 AU at baseline, p<0.001) and remained upregulated for 11 min. Furthermore, cutaneous blood flow showed two peaks at 14 (29.8 ± 25.0 AU, p=0.049) and 19 min (29.8 ± 22.6 AU, p=0.048) after treatment. Postcapillary venous filling pressure continuously increased, but showed no significant change vs. baseline in the non-specific BMI group. Subgroup analysis revealed that tissue oxygen saturation, postcapillary venous filling pressure and blood flow increased more in case of a lower BMI.

CONCLUSION

CAP increases cutaneous tissue oxygen saturation and capillary blood flow at the radial forearm of healthy volunteers. These results support recently published data on wound healing after CAP treatment. However, further studies are needed to determine if this treatment can improve the reduced microcirculation in diabetic foot ulcers. Moreover, repetitive application protocols have to be compared with a single session treatment approach.

Proteomic Changes of Tissue-Tolerable Plasma Treated Airway Epithelial Cells and Their Relation to Wound Healing

Background. The worldwide increasing number of patients suffering from nonhealing wounds requires the development of new safe strategies for wound repair. Recent studies suggest the possibility of nonthermal (cold) plasma application for the acceleration of wound closure. Methods. An in vitro wound healing model with upper airway S9 epithelial cells was established to determine the macroscopically optimal dosage of tissue-tolerable plasma (TTP) for wound regeneration, while a 2D-difference gel electrophoresis (2D-DIGE) approach was used to quantify the proteomic changes in a hypothesis-free manner and to evaluate the balance of beneficial and adverse effects due to TTP application. Results. Plasma doses from 30 s up to 360 s were tested in relation to wound closure after 24 h, 48 h, 72 h, 96 h, and 120 h, in which lower doses (30, 60, and 120 s) resulted in dose-dependent improved wound healing rate compared to untreated cells. Thereby, the 120 s dose caused significantly the best wound healing properties after 96 and 120 h. The proteome analysis combined with IPA revealed that a lot of affected stress adaptation responses are linked to oxidative stress response emphasizing oxidative stress as a possible key event in the regeneration process of epithelial cells as well as in the adaptation to plasma exposure. Further cellular and molecular functions like proliferation and apoptosis were significantly up- or downregulated by all TTP treatments but mostly by the 120 s dose. Conclusions. For the first time, we were able to show plasma effects on cellular adaptation of upper airway epithelial S9 cells improving wound healing. This is of particular interest for plasma application, for example, in the surgery field of otorhinolaryngology or internal medicine.