Antibacterial and safety tests of a flexible cold atmospheric plasma device for the stimulation of wound healing

Non-invasive physical plasma for preventing radiation dermatitis in breast cancer: Results from an intrapatient-randomised double-blind placebo-controlled trial

Background and Purpose

To investigate the effect of topical non-invasive physical plasma (NIPP), a volatile mix generated out of ambient air, on prevention of acute radiation dermatitis (RD) during and after whole-breast irradiation (WBI).

Materials and Methods

Lateral and medial breast halves were randomised within each patient to receive either 120 s of NIPP or sham treatment daily during WBI. Standard skin care with urea lotion was applied to the whole breast. Blinded acute skin toxicity was assessed weekly for each breast half separately and included clinician- (CTCAE) and patient-reported (modified RISRAS), and objective (spectrophotometry) assessments. As an additional external control, a comparable standard of care (SoC) patient collective from a previous prospective trial was used.

Results

Sixty-four patients were included. There were no significant differences between breast halves. Post-hoc comparison with a similar SoC control collective revealed OR = 0.28 (95% CI 0.11-0.76; p = 0.014) for grade ≥ 2 RD upon WBI completion, along with less hyperpigmentation (p < 0.001), oedema (p = 0.020), dry (p < 0.001) and moist desquamation (p = 0.017), pain, itching, and burning (p < 0.001 for each). Tolerability of NIPP was excellent and side effects were not observed.

Conclusion

Even though there were no differences between intrapatient-randomised breast halves, the overall incidence and severity of acute radiation-induced skin toxicity were considerably lower when compared to a prospectively collected SoC cohort. Our data suggest the potential benefit of NIPP in RD prevention. A randomised trial with a physical control group is warranted to confirm these promising results (DRKS00026225).

Effects of Nitro-Oxidative Stress on Biomolecules: Part 1-Non-Reactive Molecular Dynamics Simulations

Plasma medicine, or the biomedical application of cold atmospheric plasma (CAP), is an expanding field within plasma research. CAP has demonstrated remarkable versatility in diverse biological applications, including cancer treatment, wound healing, microorganism inactivation, and skin disease therapy. However, the precise mechanisms underlying the effects of CAP remain incompletely understood. The therapeutic effects of CAP are largely attributed to the generation of reactive oxygen and nitrogen species (RONS), which play a crucial role in the biological responses induced by CAP. Specifically, RONS produced during CAP treatment have the ability to chemically modify cell membranes and membrane proteins, causing nitro-oxidative stress, thereby leading to changes in membrane permeability and disruption of cellular processes. To gain atomic-level insights into these interactions, non-reactive molecular dynamics (MD) simulations have emerged as a valuable tool. These simulations facilitate the examination of larger-scale system dynamics, including protein-protein and protein-membrane interactions. In this comprehensive review, we focus on the applications of non-reactive MD simulations in studying the effects of CAP on cellular components and interactions at the atomic level, providing a detailed overview of the potential of CAP in medicine. We also review the results of other MD studies that are not related to plasma medicine but explore the effects of nitro-oxidative stress on cellular components and are therefore important for a broader understanding of the underlying processes.

Cold Plasma Therapy in Chronic Wounds-A Multicenter, Randomized Controlled Clinical Trial (Plasma on Chronic Wounds for Epidermal Regeneration Study): Preliminary Results

Chronic wounds (CWs) pose a significant health challenge in clinical practice. Standard wound therapy (SWT) is currently considered the gold standard. However, recent evidence suggests that cold plasma therapy (CPT) holds promise for improving CWs. In light of this, the POWER study was conducted as a multicenter, randomized clinical trial to investigate the effect of large-area plasma application compared with SWT in patients with chronic, non-healing arterial or venous wounds on the lower leg. To analyze the interim results, we employed a comprehensive range of statistical tests, including both parametric and non-parametric methods, as well as GLS model regression and an ordinal mixed model. Our findings clearly demonstrate that CPT therapy significantly accelerates wound closure compared with SWT. In fact, complete wound closure was exclusively observed in the CPT group during the intervention period. Additionally, the CPT group required significantly less antibiotic therapy (4%) compared with the SWT group (23%). Furthermore, CPT led to a significant reduction in wound pain and improved quality of life compared with SWT. In conclusion, the study highlights that the combination of CPT and SWT surpasses monotherapy with SWT alone.

A novel approach to expedite wound healing with plasma brush of cold flame

Excessive or persistent infection is a major contributing factor in impeding chronic wound healing. Wound bed preparations using antiseptics do not necessarily target the entire bacterial spectrum, and the highly proliferating granulation tissue may be sensitive to the cytotoxic effects, impairing tissue repair. Non-thermal gas atmospheric pressure plasmas are partially ionized gases that contain highly reactive particles while the gas phase remains near room temperature, thus having the capability of accessing small irregular cavities and fissures and killing bacteria because of the diffusive nature of gas phase plasma species that are chemically reactive, providing an ideal approach to topical wound disinfection. A non-thermal plasma brush device of novel design has been developed that is suitable for clinical application in the disinfection of oral and wound bacteria. In vivo studies have indicated that the plasma brush treatment rendered no harmful effect on healthy skin or tissues, while it could improve wound healing in Pseudomonas aeruginosa biofilm infected wounds exposed to an optimized treatment with argon plus 1% nitrogen (Ar + N2) plasma.

Mechanisms of bacterial inhibition and tolerance around cold atmospheric plasma

The grim situation of bacterial infection has undoubtedly become a major threat to human health. In the context of frequent use of antibiotics, a new bactericidal method is urgently needed to fight against drug-resistant bacteria caused by non-standard use of antibiotics. Cold atmospheric plasma (CAP) is composed of a variety of bactericidal species, which has excellent bactericidal effect on microbes. However, the mechanism of interaction between CAP and bacteria is not completely clear. In this paper, we summarize the mechanisms of bacterial killing by CAP in a systematic manner, discuss the responses of bacteria to CAP treatment that are considered to be related to tolerance and their underlying mechanisms, review the recent advances in bactericidal applications of CAP finally. This review indicates that CAP inhibition and tolerance of survival bacteria are a set of closely related mechanisms and suggests that there might be other mechanisms of tolerance to survival bacteria that had not been discovered yet. In conclusion, this review shows that CAP has complex and diverse bactericidal mechanisms, and has excellent bactericidal effect on bacteria at appropriate doses. KEY POINTS: • The bactericidal mechanism of CAP is complex and diverse. • There are few resistant bacteria but tolerant bacteria during CAP treatment. • There is excellent germicidal effect when CAP in combination with other disinfectants.

Modulation of the Tumor-Associated Immuno-Environment by Non-Invasive Physical Plasma

Over the past 15 years, investigating the efficacy of non-invasive physical plasma (NIPP) in cancer treatment as a safe oxidative stress inducer has become an active area of research. So far, most studies focused on the NIPP-induced apoptotic death of tumor cells. However, whether NIPP plays a role in the anti-tumor immune responses need to be deciphered in detail. In this review, we summarized the current knowledge of the potential effects of NIPP on immune cells, tumor-immune interactions, and the immunosuppressive tumor microenvironment. In general, relying on their inherent anti-oxidative defense systems, immune cells show a more resistant character than cancer cells in the NIPP-induced apoptosis, which is an important reason why NIPP is considered promising in cancer management. Moreover, NIPP treatment induces immunogenic cell death of cancer cells, leading to maturation of dendritic cells and activation of cytotoxic CD8⁺ T cells to further eliminate the cancer cells. Some studies also suggest that NIPP treatment may promote anti-tumor immune responses via other mechanisms such as inhibiting tumor angiogenesis and the desmoplasia of tumor stroma. Though more evidence is required, we expect a bright future for applying NIPP in clinical cancer management.

Topical Hyperbaric Oxygen Therapy Versus Local Ozone Therapy in Healing of Venous Leg Ulcers

BACKGROUND

the treatment of venous leg ulcers still poses a difficult interdisciplinary medical problem. The aim of this study was to compare the therapeutic efficacy of local hyperbaric oxygen therapy with local ozone therapy in the treatment of venous leg ulcers.

MATERIALS

this study included 114 patients; 60 males (52.63%) and 54 females (47.36%) of ages ranging between 39 and 88 years (mean age: 68.9 ± 9.8 years) with venous leg ulcers, who underwent topical hyperbaric oxygen therapy (group I) and local ozone therapy (group II). In each of the study groups, the patients underwent 30 therapeutic procedures lasting 30 min each. The progress in wound healing was evaluated by computerized planimetry, and the intensity of pain was assessed with the use of the Visual Analogue Scale (VAS).

RESULTS

in both groups of treated patients, a statistically significant (p = 0.000001) reduction in the area of treated ulcers was achieved. In group I, the wound area decreased by an average of 69.67 ± 22.52%, from 7.55 ± 2.99 cm² to 2.78 ± 2.43 cm², and in group II, by an average of 41.33 ± 21.31%, from 7.36 ± 2.82 cm² to 4.62 ± 2.76 cm². In both groups of patients, a statistically significant (p = 0.000001) reduction in the intensity of pain ailments was observed: in group I, by an average of 0.55 ± 0.54 points, and in group II, by an average of 2.33 ± 0.82 points on the VAS scale.

CONCLUSIONS

local hyperbaric oxygen therapy and local ozone therapy cause a statistically significant reduction in the surface area of venous leg ulcers as well as in the intensity of pain. Better results were observed after the application of local hyperbaric oxygen therapy procedures.

Revealing low-temperature plasma efficacy through a dose-rate assessment by DNA damage detection combined with machine learning models

Low-temperature plasmas have quickly emerged as alternative and unconventional types of radiation that offer great promise for various clinical modalities. As with other types of radiation, the therapeutic efficacy and safety of low-temperature plasmas are ubiquitous concerns, and assessing their dose rates is crucial in clinical settings. Unfortunately, assessing the dose rates by standard dosimetric techniques has been challenging. To overcome this difficulty, we proposed a dose-rate assessment framework that combined the predictive modeling of plasma-induced damage in DNA by machine learning with existing radiation dose-DNA damage correlations. Our results indicated that low-temperature plasmas have a remarkably high dose rate that can be tuned by various process parameters. This attribute is beneficial for inducing radiobiological effects in a more controllable manner.

Cold Atmospheric Plasma Jet Treatment Improves Human Keratinocyte Migration and Wound Closure Capacity without Causing Cellular Oxidative Stress

Cold Atmospheric Plasma (CAP) is an emerging technology with great potential for biomedical applications such as sterilizing equipment and antitumor strategies. CAP has also been shown to improve skin wound healing in vivo, but the biological mechanisms involved are not well known. Our study assessed a possible effect of a direct helium jet CAP treatment on keratinocytes, in both the immortalized N/TERT-1 human cell line and primary keratinocytes obtained from human skin samples. The cells were covered with 200 µL of phosphate buffered saline and exposed to the helium plasma jet for 10−120 s. In our experimental conditions, micromolar concentrations of hydrogen peroxide, nitrite and nitrate were produced. We showed that long-time CAP treatments (≥60 s) were cytotoxic, reduced keratinocyte migration, upregulated the expression of heat shock protein 27 (HSP27) and induced oxidative cell stress. In contrast, short-term CAP treatments (<60 s) were not cytotoxic, did not affect keratinocyte proliferation and differentiation, and did not induce any changes in mitochondria, but they did accelerate wound closure in vitro by improving keratinocyte migration. In conclusion, these results suggest that helium-based CAP treatments improve wound healing by stimulating keratinocyte migration. The study confirms that CAP could be a novel therapeutic method to treat recalcitrant wounds.

Non-Invasive Physical Plasma for Preventing Radiation Dermatitis in Breast Cancer: A First-In-Human Feasibility Study

Radiation dermatitis (RD) is the most common acute side effect of breast irradiation. More than a century following the therapeutic utilisation of X-rays, potent preventative and therapeutic options are still lacking. Non-invasive physical plasma (NIPP) is an emerging approach towards treatment of various dermatological disorders. In this study, we sought to determine the safety and feasibility of a NIPP device on RD. Thirty patients undergoing hypofractionated whole-breast irradiation were included. Parallel to radiation treatment, the irradiated breast was treated with NIPP with different application regimens. RD was assessed during and after NIPP/radiation, using clinician- and patient-reported outcomes. Additionally, safety and feasibility features were recorded. None of the patients was prescribed topical corticosteroids and none considered the treatment to be unpleasant. RD was less frequent and milder in comparison with standard skin care. Neither NIPP-related adverse events nor side effects were reported. This proven safety and feasibility profile of a topical NIPP device in the prevention and treatment of RD will be used as the framework for a larger intrapatient-randomised double-blind placebo-controlled trial, using objective and patient-reported outcome measures as an endpoint.

The In-Vitro Activity of a Cold Atmospheric Plasma Device Utilizing Ambient Air against Bacteria and Biofilms Associated with Periodontal or Peri-Implant Diseases

Due to its antimicrobial and healing-promoting effects, the application of cold atmospheric plasma (CAP) appears to be a promising modality in various fields of general medicine and dentistry. The aim of the present study was to evaluate the antibacterial and anti-biofilm activity of a handheld device utilizing ambient air for plasma generation. Suspensions of 11 oral bacteria (among them Fusobacterium nucleatum, Porphyromonas gingivalis, Parvimonas micra, Streptococcus gordonii, and Tannerella forsythia) were exposed to CAP for 10, 30, 60, and 120 s. Before and after treatment, colony forming unit (CFU) counts were determined. Then, 12-species biofilms were cultured on dentin and titanium specimens, and CAP was applied for 30, 60, and 120 s before quantifying CFU counts, biofilm mass, and metabolic activity. A reduction of ≥3 log₁₀ CFU, was found for ten out of the eleven tested species at 30 s (except for T. forsythia) and for all species at 60 s. For biofilm grown on dentin and titanium specimens, the log₁₀ reductions were 2.43 log₁₀ CFU/specimen and by about 4 log₁₀ CFU/specimen after 120 s of CAP. The CAP application did not reduce the biomass significantly, the metabolic activity of the biofilms on dentin and titanium decreased by 98% and 95% after 120 s of CAP. An application of 120 s of CAP had no cytotoxic effect on gingival fibroblasts and significantly increased the adhesion of gingival fibroblasts to the titanium surface. These results are promising and underline the potential of CAP for implementation in periodontal and peri-implantitis therapy.

Chronic wounds treated with cold atmospheric plasmajet versus best practice wound dressings: a multicenter, randomized, non-inferiority trial

The use of phase-adapted wound dressings represents best practice (BP) in chronic wound treatment. However, efficacy is often limited and associated care requirements are high. Cold atmospheric plasmajet (CAP-jet) is a promising new therapeutic tool for these wounds. In the present multicenter, randomized, open-label, prospective, clinical trial, non-inferiority of the CAP-jet versus BP was assessed in 78 patients with infected or non-infected chronic wounds of different etiology. Primary outcome measure was the sum of granulation tissue, furthermore wound area reduction, healing rate, time to complete healing, changes in wound pH value, infection score, exudate level and local tolerability were assessed. In CAP-jet treated wounds compared to control, the sum of granulation tissue was significantly higher (p < 0.0001) and wound area reduced significantly faster (p < 0.001). Furthermore, wound pH value decreased significantly faster (p = 0.0123) and local infection was overcome more rapidly by CAP-jet therapy. In 58.97% CAP-jet- vs. 5.13% BP-treated patients, complete healing of chronic ulcers was documented after 6 weeks. Treatment with CAP-jet appeared not only non-inferior, but even superior to BP in all wound entities analyzed with a favorable tolerability profile. Thus, treatment with the CAP-jet provides beneficial effects in chronic wound treatment regarding promotion of the wound healing process.

Unraveling the permeation of reactive species across nitrated membranes by computer simulations

Reactive oxygen and nitrogen species (RONS) are involved in many biochemical processes, including nitro-oxidative stress that causes cancer cell death, observed in cancer therapies such as photodynamic therapy and cold atmospheric plasma. However, their mechanisms of action and selectivity still remain elusive due to the complexity of biological cells. For example, it is not well known how RONS generated by cancer therapies permeate the cell membrane to cause nitro-oxidative damage. There are many studies dedicated to the permeation of RONS across native and oxidized membranes, but not across nitrated membranes, another lipid product also generated during nitro-oxidative stress. Herein, we performed molecular dynamics (MD) simulations to calculate the free energy barrier of RONS permeation across nitrated membranes. Our results show that hydrophilic RONS, such as hydroperoxyl radical (HO₂) and peroxynitrous acid (ONOOH), have relatively low barriers compared to hydrogen peroxide (H₂O₂) and hydroxyl radical (HO), and are more prone to permeate the membrane than for the native or peroxidized membranes, and similar to aldehyde-oxidized membranes. Hydrophobic RONS like molecular oxygen (O₂), nitrogen dioxide (NO₂) and nitric oxide (NO) even have insignificant barriers for permeation. Compared to native and peroxidized membranes, nitrated membranes are more permeable, suggesting that we must not only consider oxidized membranes during nitro-oxidative stress, but also nitrated membranes, and their role in cancer therapies.