Nitric oxide: a newly discovered function on wound healing

Multifaceted Study of the Interactions between CPO-27-Ni and Polyurethane and Their Impact on Nitric Oxide Release Performance

A multifaceted study involving focused ion beam scanning electron microscopy techniques, mechanical analysis, water adsorption measurements, and molecular simulations is employed to rationalize the nitric oxide release performance of polyurethane films containing 5, 10, 20, and 40 wt % of the metal-organic framework (MOF) CPO-27-Ni. The polymer and the MOF are first demonstrated to exhibit excellent compatibility. This is reflected in the even distribution and encapsulation of large wt % MOF loadings throughout the full thickness of the films and by the rather minimal influence of the MOF on the mechanical properties of the polymer at low wt %. The NO release efficiency of the MOF is attenuated by the polymer and found to depend on wt % of MOF loading. The formation of a fully connected network of MOF agglomerates within the films at higher wt % is proposed to contribute to a more complex guest transport in these formulations, resulting in a reduction of NO release efficiency and film ductility. An optimum MOF loading of 10 wt % is identified for maximizing NO release without adversely impacting the polymer properties. Bactericidal efficacy of released NO from the films is demonstrated against Pseudomonas aeruginosa, with a >8 log₁₀ reduction in cell density observed after a contact period of 24 h.

On the Liquid Chemistry of the Reactive Nitrogen Species Peroxynitrite and Nitrogen Dioxide Generated by Physical Plasmas

Cold physical plasmas modulate cellular redox signaling processes, leading to the evolution of a number of clinical applications in recent years. They are a source of small reactive species, including reactive nitrogen species (RNS). Wound healing is a major application and, as its physiology involves RNS signaling, a correlation between clinical effectiveness and the activity of plasma-derived RNS seems evident. To investigate the type and reactivity of plasma-derived RNS in aqueous systems, a model with tyrosine as a tracer was utilized. By high-resolution mass spectrometry, 26 different tyrosine derivatives including the physiologic nitrotyrosine were identified. The product pattern was distinctive in terms of plasma parameters, especially gas phase composition. By scavenger experiments and isotopic labelling, gaseous nitric dioxide radicals and liquid phase peroxynitrite ions were determined as dominant RNS. The presence of water molecules in the active plasma favored the generation of peroxynitrite. A pilot study, identifying RNS driven post-translational modifications of proteins in healing human wounds after the treatment with cold plasma (kINPen), demonstrated the presence of in vitro determined chemical pathways. The plasma-driven nitration and nitrosylation of tyrosine allows the conclusion that covalent modification of biomolecules by RNS contributes to the clinically observed impact of cold plasmas.

Advances in inorganic-based colloidal nanovehicles functionalized for nitric oxide delivery

Nitric oxide (NO) is an important pharmaceutical agent of considerable therapeutic interest ascribed to its vasodilative, tumoricidal and antibacterial effects. Rapid development of functional nanomaterials has provided opportunities for us to achieve controllable exogenous delivery of NO. In the current review, a variety of functionalized colloidal nanovehicles that have been developed to date for nitric oxide delivery are reported. Specifically, we focus on inorganic nanomaterials such as semiconductor quantum dots, silica nanoparticles, upconversion nanomaterials, carbon/graphene nanodots, gold nanoparticles, iron oxide nanoparticles as the functional or/and supporting materials to carry NO donors. N-diazeniumdiolates, S-nitrosothiols, nitrosyl metal complexes and organic nitrates as main types of NO donors have their own unique properties and molecular structures. Conjugating the NO donors of different forms with appropriate nanomaterials results in NO delivery nanovehicles capable of releasing NO in a dose-controllable or/and on-demand manner. We also consider the therapeutic applications of those NO delivery nanovehicles, especially their applications for cancer therapy. In the end, we discuss possible future directions for developing exogenous NO delivery systems with more desired structure and improved performance. This review aims to offer the readers an overall view of the advances in functionalized colloidal nanovehicles for NO delivery. It will be attractive to scientists and researchers in the areas of material science, nanotechnology, biomedical engineering, chemical biology, etc.

Development and Characterization of a Non-Thermal Plasma Source for Therapeutic Treatments

OBJECTIVE

an innovative non-thermal plasma (NTP) system constituted by a radiofrequency (RF) power generator directly coupled to a treatment probe is described and characterized. This system is intended to be applied as a medical device for therapeutic treatments.

METHODS

electrical characterization of the radiofrequency power generator supplying the treatment probe was performed. Meanwhile, generated NTP was optically analyzed. Obtained data were studied to establish the safety profile of plasma application on heat sensitive matter.

RESULTS

the NTP system was validated through bacterial deactivation trials, as well as, of being capable of deactivating carcinogenic cells. Besides promoting and accelerating wound closure in vivo performed in mice, demonstrating faster healing than that done with conventional treatments.

CONCLUSION

the NTP system's characterization is an essential stage to determine the adequate application of the generated plasma over organic media. The therapeutic benefits of the NTP system were proved by the development of in vivo experiences involving laboratory mice.

SIGNIFICANCE

the generated NTP interacts with surrounding air particles producing reactive oxygen and nitrogen species, which, exhibit bactericidal and antiseptic effects due to their strong biochemical reactivity; functioning like critical mediators in animal physiology and promoting wound healing processes. These properties make the NTP system a feasible technology intended for therapeutic treatments.

In vitro and in vivo testing of nanofibrous membranes doped with alaptide and L-arginine for wound treatment

We have prepared a candidate biocompatible construct for skin wound healing based on electrospun polycaprolactone (PCL) nanofibrous membranes. The membrane material was loaded either with L-arginine or with alaptide, or with a mixture of both bioactive components. Alaptide is a spirocyclic synthetic dipeptide, an analogue of melanocyte-stimulating hormone release-inhibiting factor. L-arginine is an amino acid with a basic guanidine side chain. It is a direct precursor of nitric oxide, which plays a pivotal role in skin repair. The presence and the distribution of the additives were proved with high-performance liquid chromatography, Fourier-transform infrared spectroscopy and Raman spectroscopy. The influence of L-arginine and alaptide on the morphology of the membrane was characterized using scanning electron microscopy. No statistically significant correlation between fiber diameter and drug concentration was observed. The membranes were then tested in vitro for their cytotoxicity, using primary human dermal fibroblasts, in order to obtain the optimal concentrations of the additives for in vivo tests in a rat model. The membranes with the highest concentration of L-arginine (10 wt. %) proved to be cytotoxic. The membranes with alaptide in concentrations from 0.1 to 2.5 wt.%, and with the other L-arginine concentrations (1 and 5 wt.%), did not show high toxicity. In addition, there was no observed improvement in cell proliferation on the membranes. The in vivo experiments revealed that membranes with 1.5 wt.% of alaptide or with 1.5 wt.% of alaptide in combination with 5 wt.% of L-arginine markedly accelerated the healing of skin incisions, and particularly the healing of skin burns, i.e. wounds of relatively large extent. These results indicate that our newly-developed nanofibrous membranes are promising for treating wounds with large damaged areas, where a supporting material is needed.

Hydrogels based on low-methoxyl amidated citrus pectin and flaxseed gum formulated with tripeptide glycyl-l-histidyl-l-lysine improve the healing of experimental cutting wounds in rats

Hydrogels based on natural and modified polysaccharides represent growing group of suitable matrices for the construction of effective wound healing materials. Bioactive tripeptide glycyl-l-histidyl-l-lysine and amino acid α-l-arginine are known to accelerate wound healing and skin repair. In this study, hydrogels based on low-methoxyl amidated citrus pectin or flaxseed gum were prepared and used for the transport of these healing agents to the experimental cutting wounds affected by extensive skin damage. Fourier-transform infrared spectroscopy, rheology, differential scanning calorimetry, scanning electron microscopy, swelling and release tests confirmed that these hydrogels differed in structure and physical properties. The cationic tripeptide was found to bind to carboxylic groups in LMA pectin, and the C3OH hydroxyl and ring oxygen O5 are involved in this interaction. The pectin hydrogel showed high viscosity and strong elastic properties, while the flaxseed gum hydrogel was characterised as a viscoelastic system of much lower viscosity. The former hydrogel released the drugs very slowly, while the latter hydrogel demonstrated zero order releasing kinetics optimal for drug delivery. In the in vivo wound healing testing on rats, both polysaccharide hydrogels improved the healing process mediated by the mentioned biomolecules. The tripeptide applied in the hydrogels showed significantly higher healing degree and lower healing time than in the control animals without treatment and when it was applied in an aqueous solution. Despite the absence of a synergistic effect, the mixture of the tripeptide and α-l-arginine in the hydrogels was also quite effective in wound healing. According to histological analysis, complete healing was achieved only when using the tripeptide in the flaxseed gum hydrogel. These observations might have an important prospect in clinical application of polysaccharide hydrogels.

Potassium bromate cytotoxicity in the Wister rat model of chronic gastric ulcers: Possible reversal by protocatechuic acid

The interaction between ingested xenobiotics and the gastrointestinal epithelium influences the possibility of gut epithelial cytotoxicity and systemic toxicity. Potassium bromate (KBrO₃ ) has been shown to perturb the central nervous system and it may be carcinogenic, albeit it is used as a food additive. This highlights the need to understand KBrO₃ 's effect on the stomach epithelium. Here, we report the cytotoxic potential of KBrO₃ in an ulcerated stomach, as well as possible cytoprotection by the polyphenol - protocatechuic acid. Potassium bromate (12.5 mg/kg) and protocatechuic acid (120 mg/kg) were administered orally while omeprazole (20 mg/kg) was used as standard. Potassium bromate exacerbated gastric ulcers, increased malonaldehyde levels, catalase, and sodium pump activities, but reduced nitric oxide levels. Potassium bromate further increased mast cell count in the muscularis mucosa, while inducing chronic inflammation and moderate angiogenesis in the gastric mucosa. Our results delineate KBrO₃ -induced gastric epithelial cytotoxicity that is ameliorated by protocatechuic acid. PRACTICAL APPLICATIONS: Potassium bromate is a known food additive in the baking, brewing, and cheese-making process. Conversely, protocatechuic acid (3,4-dihydroxybenzoic acid) is the polyphenolic content of plants like Hibiscus sabdariffa L that are commonly consumed as herbal drink, food, spices, and used in folk medicine. This study reports the cytoprotective effect of protocatechuic acid against gastric mucosa ulceration that has been aggravated by potassium bromate.

Cold Atmospheric Pressure Plasma in Wound Healing and Cancer Treatment

Plasma medicine is gaining increasing attention and is moving from basic research into clinical practice. While areas of application are diverse, much research has been conducted assessing the use of cold atmospheric pressure plasma (CAP) in wound healing and cancer treatment—two applications with entirely different goals. In wound healing, a tissue-stimulating effect is intended, whereas cancer therapy aims at killing malignant cells. In this review, we provide an overview of the latest clinical and some preclinical research on the efficacy of CAP in wound healing and cancer therapy. Furthermore, we discuss the current understanding of molecular signaling mechanisms triggered by CAP that grant CAP its antiseptic and tissue regenerating or anti-proliferative and cell death-inducing properties. For the efficacy of CAP in wound healing, already substantial evidence from clinical studies is available, while evidence for therapeutic effects of CAP in oncology is mainly from in vitro and in vivo animal studies. Efforts to elucidate the mode of action of CAP suggest that different components, such as ultraviolet (UV) radiation, electromagnetic fields, and reactive species, may act synergistically, with reactive species being regarded as the major effector by modulating complex and concentration-dependent redox signaling pathways.

Nitric Oxide-Releasing Thermoresponsive Pluronic F127/Alginate Hydrogel for Enhanced Antibacterial Activity and Accelerated Healing of Infected Wounds

Nitric oxide (NO), a highly reactive and lipophilic molecule, is one of the molecules present in the wound environment and implicated as an important regulator in all phases of wound healing. Here, we developed an NO-releasing thermoresponsive hydrogel (GSNO-PL/AL) composed of S-nitrosoglutathione (GSNO), pluronic F127 (PL), and alginate (AL) for the treatment of infected wounds. The GSNO was incorporated into the thermoresponsive PL/AL hydrogel, and differential scanning calorimetry techniques were used for the hydrogel characterization. The hydrogel was assessed by in vitro NO release, antibacterial activity, cytotoxicity, and wound-healing activity. The GSNO-PL/AL hydrogel demonstrated thermal responsiveness and biocompatibility, and it showed sustained NO release for 7 days. It also exhibited potent bactericidal activity against Gram-positive methicillin-resistant Staphylococcus aureus and Gram-negative multidrug-resistant Pseudomonas aeruginosa (MRPA). Moreover, the GSNO-PL/AL treatment of MRPA-infected wounds accelerated healing with a reduced bacterial burden in the wounds. The GSNO-PL/AL hydrogel would be a promising option for the treatment of infected wounds.

Interaction of Staphylococcus aureus and Host Cells upon Infection of Bronchial Epithelium during Different Stages of Regeneration

The primary barrier that protects our lungs against infection by pathogens is a tightly sealed layer of epithelial cells. When the integrity of this barrier is disrupted as a consequence of chronic pulmonary diseases or viral insults, bacterial pathogens will gain access to underlying tissues. A major pathogen that can take advantage of such conditions is Staphylococcus aureus, thereby causing severe pneumonia. In this study, we investigated how S. aureus responds to different conditions of the human epithelium, especially nonpolarization and fibrogenesis during regeneration using an in vitro infection model. The infective process was monitored by quantification of the epithelial cell and bacterial populations, fluorescence microscopy, and mass spectrometry. The results uncover differences in bacterial internalization and population dynamics that correlate with the outcome of infection. Protein profiling reveals that, irrespective of the polarization state of the epithelial cells, the invading bacteria mount similar responses to adapt to the intracellular milieu. Remarkably, a bacterial adaptation that was associated with the regeneration state of the epithelial cells concerned the early upregulation of proteins controlled by the redox-responsive regulator Rex when bacteria were confronted with a polarized cell layer. This is indicative of the modulation of the bacterial cytoplasmic redox state to maintain homeostasis early during infection even before internalization. Our present observations provide a deeper insight into how S. aureus can take advantage of a breached epithelial barrier and show that infected epithelial cells have limited ability to respond adequately to staphylococcal insults.

A novel multifaceted approach for wound healing: Optimization and in vivo evaluation of spray dried tadalafil loaded pro-nanoliposomal powder

The topical delivery of nanotherapeutics at the injury site for skin regeneration has received increasing attention as a strategy for wound treatment. This study aimed to investigate the preparation of spray dried tadalafil loaded pro-nanoliposomes powder as a novel system to accelerate wound healing process. The optimization was carried out employing 3² factorial design based on phospholipid and cholesterol concentrations. The physicochemical characterizations, in vitro cellular assessment and in vivo performance were evaluated. The results obtained pointed out that phospholipid concentration presented a positive effect on the entrapment efficacy and particle size, while cholesterol hindered the entrapment efficacy yet presented a prominent influence on particle size. Moreover, the optimized formulation showed a sustained release, high zeta potential and uniform spherical particles indicating entrapment of tadalafil in its amorphous state as demonstrated by FTIR and XPRD results. Cell viability and in vitro scratch assay demonstrated no cytotoxicity on human fibroblast cell lines and the ability of the drug and optimized formulation to promote cell migration. In vivo wound healing studies revealed significantly higher wound closure rates for areas treated with optimized loaded-formulation (65.95±6.47%) compared to unloaded formulation (29.78±9.65%), free drug (38.87±11.44%) and sham group (10.22±5.11%). In the in vivo study, histopathological specimens supported the previous results with presentation of cascade of healing elements via the angiogenetic activity of tadalafil. These outcomes provide an insight of a novel and emerging therapeutic drug system for wound treatment in clinical practice.

Enzyme Mimics for the Catalytic Generation of Nitric Oxide from Endogenous Prodrugs

The highly diverse biological roles of nitric oxide (NO) in both physiological and pathophysiological processes have prompted great interest in the use of NO as a therapeutic agent in various biomedical applications. NO can exert either protective or deleterious effects depending on its concentration and the location where it is delivered or generated. This double-edged attribute, together with the short half-life of NO in biological systems, poses a major challenge to the realization of the full therapeutic potential of this molecule. Controlled release strategies show an admirable degree of precision with regard to the spatiotemporal dosing of NO but are disadvantaged by the finite NO deliverable payload. In turn, enzyme-prodrug therapy techniques afford enhanced deliverable payload but are troubled by the inherent low stability of natural enzymes, as well as the requirement to control pharmacokinetics for the exogenous prodrugs. The past decade has seen the advent of a new paradigm in controlled delivery of NO, namely localized bioconversion of the endogenous prodrugs of NO, specifically by enzyme mimics. These early developments are presented, successes of this strategy are highlighted, and possible future work on this avenue of research is critically discussed.

Functional Applications of Polyarginine-Hyaluronic Acid-Based Electrostatic Complexes

Background: Electrostatic complexes of poly (l-Arginine) (pArg) and hyaluronic acid (HA) have been investigated for their functional applications to supply free or polymeric form of l-Arginine (Arg) to target cells. As a vital amino acid, Arg plays significant role in multitude of pathophysiological processes ranging from wound healing to cancer. However, serum arginase expression and toxicity of Arg at cellular level renders exogenous delivery of this amino acid a challenging task. We showed that polyarginine-hyaluronic acid ionic nanocomplexes (pArg-HA iNCs) could be an effective way to deliver Arg to target cell populations. Materials and Methods: These electrostatic complexes were prepared by mixing HA (average m.w. of 200 kDa) with pArg (m.w. 5-15 kDa; Sigma) in aqueous solutions and purifying over glycerol. Nanocomplexes were characterized for their particle size, surface charge, capacity to release l-Arg, and intracellular uptake of complexes. Results: Synthesized nanocomplexes showed hydrodynamic diameter ranging from 140-306 nm depending on the content of pArg or HA within the formulation. With surface charge (ζ-potential) of -29 mV, the nanocomplexes showed pH-dependent release of Arg. At pH 7.4, pArg-HA iNCs released 30% of the total Arg-content, while at pH 5.0, 60% of Arg was released after 24 h. These electrostatically stabilized complexes were found to promote growth of human dermal fibroblasts (HDF) in wound-healing assay and increased nitric oxide (NO) activity in these cells in a time-dependent manner. Nanocomplexes also showed cellular uptake and enhanced dose-dependent toxicity against two pancreatic cancer cell lines, i.e. MIA PaCa-2 and Panc-1. Interestingly, the cytotoxic effect was synergized upon pre-treatment of the cells with a frontline chemotherapeutic agent, gemcitabine (GEM), and was not observed when the cells were treated with Arg alone. Conclusion: As such, this communication shows the prospect of pArg-HA iNC electrostatic nanocomplexes to interact and interfere with intracellular Arg metabolic machinery conducive to rescuing different pathological conditions.

The evolving landscape for cellular nitric oxide and hydrogen sulfide delivery systems: A new era of customized medications

Nitric oxide (NO) and hydrogen sulfide (H2S) are industrial toxins or pollutants; however, both are produced endogenously and have important biological roles in most mammalian tissues. The recognition that these gasotransmitters have a role in physiological and pathophysiological processes has presented opportunities to harness their intracellular effects either through inhibition of their production; or more commonly, through inducing their levels and or delivering them by various modalities. In this review article, we have focused on an array of NO and H2S donors, their hybrids with other established classes of drugs, and the various engineered delivery platforms such a fibers, polymers, nanoparticles, hydrogels, and others. In each case, we have reviewed the rationale for their development.

The Wound Healing Property of N-Methyl-(2S,4R)-trans-4-Hydroxy-L-Proline from Sideroxylon obtusifolium is Related to its Anti-Inflammatory and Antioxidant Actions

Wound healing involves the interaction of blood cells, proteins, proteases, growth factors, and extracellular matrix components. Inflammation is one of the first events occurring during this process. Previously, we showed that the N-Methyl-(2S,4R)-trans-4-Hydroxy-L-Proline (NMP) from Sideroxylon obtusifolium leaves (a Brazilian medicinal species) presents an anti-inflammatory action. Considering inflammation as an important event in the wound healing process, the objectives were to investigate the topical effects of the NMP gel on a mice wound-induced model. Male Swiss mice were divided into 4 groups: Sham (surgical procedure only), Control (gel-base treated), and 3% or 10% NMP gel-treated groups. Measurements of wound areas and microscopic analyses (HE [hematoxylin-eosin] and PSR [picrosirius red] stainings) were carried out, at the 7th and 12th, days after the wound induction. Furthermore, immunohistochemical assays for iNOS (inducible nitric oxide synthase) and COX-2 (cyclooxygenase-2) and biochemical measurements for TBARS (thiobarbituric acid reactive substances), GSH (glutathione), and myeloperoxidase (MPO) were also performed, at the second day after the wound induction. The work showed that NMP decreases the wound areas, after topical application, relatively to the Sham and Control groups. In addition, microscopic alterations were reduced and collagen deposition was increased, at the 7th and 12th days, in the 10% NMP group. While iNOS and COX-2 immunostainings and GSH contents increased, in relation to the Sham and Control groups, TBARS and MPO decreased. Altogether, the results showed NMP to improve the wound healing process, by upregulating iNOS and COX-2 activities, reducing lipid peroxidation and MPO activity, and increasing GSH contents. In addition, NMP certainly contributes to the increased collagen deposition. These data may stimulate translational studies dealing with the possible use of NMP from Sideroxylon obtusifolium or from other sources for the management of wound healing.

Cu∥-loaded polydopamine coatings with in situ nitric oxide generation function for improved hemocompatibility

NO is the earliest discovered gas signal molecule which is produced by normal healthy endothelial cells, and it has many functions, such as maintaining cardiovascular homeostasis, regulating vasodilation, inhibiting intimal hyperplasia and preventing atherosclerosis in the blood system. Insufficient NO release is often observed in the pathological environment, for instance atherosclerosis. It was discovered that NO could be released from the human endogenous NO donor by many compounds, and these methods can be used for the treatment of certain diseases in the blood system. In this work, a series of copper-loaded polydopamine (PDA) coatings were produced through self-polymerization time for 24, 48 and 72 h. The chemical composition and structure, coating thickness and hydrophilicity of the different copper-loaded PDA coatings surfaces were characterized by phenol hydroxyl quantitative, X-ray photoelectron spectroscopy, ellipsometry atomic force microscopy and water contact angles. The results indicate that the thickness and the surface phenolic hydroxyl density of the PDA coatings increased with the polymerization time.This copper-loaded coating has glutathione peroxidase-like activity, and it has the capability of catalyzing NO releasing from GSNO. The surface of the coating showed desirable hemocompatibility, the adhesion and activation of platelets were inhibited on the copper-loaded coatings. At the same time, the formation of the thrombosis was also suppressed. These copper-loaded PDA coatings could provide a promising platform for the development of blood contact materials.

Cartilage acidic protein 1 promotes increased cell viability, cell proliferation and energy metabolism in primary human dermal fibroblasts

Cartilage acidic protein 1 (CRTAC1) is an extracellular matrix protein of human chondrogenic tissue that is also present in other vertebrates, non-vertebrate eukaryotes and in some prokaryotes. The function of CRTAC1 remains unknown but the protein's structure indicates a role in cell-cell or cell-matrix interactions and calcium-binding. The aim of the present study was to evaluate the in vitro effects of hCRTAC1-A on normal human dermal fibroblasts (NHDF). A battery of in vitro assays (biochemical and PCR), immunofluorescence and a biosensor approach were used to characterize the protein's biological activities on NHDF cells in a scratch assay. Gene expression analysis revealed that hCRTAC1-A protein is associated with altered levels of expression for genes involved in the processes of cell proliferation (CXCL12 and NOS2), cell migration (AQP3 and TNC), and extracellular matrix-ECM regeneration and remodeling (FMOD, TIMP1, FN1) indicating a role for hCRTAC1-A in promoting these activities in a scratch assay. In parallel, the candidate processes identified by differential gene transcription were substantiated and extended using Electric cell-substrate impedance sensing (ECIS) technology, immunofluorescence and cell viability assays. Our findings indicate that hCRTAC1-A stimulated cell proliferation, migration and ECM production in primary human fibroblasts in vitro.

Asiaticoside nitric oxide gel accelerates diabetic cutaneous ulcers healing by activating Wnt/β-catenin signaling pathway

Diabetic ulcers, gangrene, local infections and other traumatic symptoms of wound healing are all directly related. Promoting the early healing of diabetic cutaneous ulcers (DCU) and reducing the disability and treatment costs is an important research project integrating traditional Chinese and Western medicine. Nitric oxide (NO) is a key component of wound healing, and endogenous NO secretion is insufficient during the development of DCU. It has been reported that exogenous NO can promote wound healing, but exogenous NO has a short half-life and is difficult to adhere to the skin. Asiaticoside (AC) is extracted from the traditional Chinese medicine Centella asiatica, and has angiogenic, anticancer, antioxidant, anti-inflammatory, and wound-healing effects. Therefore, our study is based on the hypothesis that the combination of AC and NO to treat DCU is possible. In this study we considered gels of AC and NO, and evaluated the effects of the gel on DCU healing. Based on our study, it was found that the combined effect of asiaticoside and NO could accelerate the healing rate of DCU wounds. The asiaticoside NO gel can inhibit the growth of bacteria in the wound surface, alleviate the inflammatory reaction of wound, and increase the expression of VEGF, iNOS, eNOS and CD34. Our research shows that asiaticoside NO gel may promote DCU wound healing by regulating Wnt/β-Catenin signaling pathway. It will provide new targets and strategies for the diagnosis and treatment of DCU.

New Disposable Nitric Oxide Sensor Fabrication Using GaN Nanowires

Gallium nitride (GaN) nanowires anchored on the surface of cost-effective pencil graphite electrodes (PGEs) have been developed as a new disposable nitric oxide (NO) sensor through a hydrothermal method followed by annealing treatment. The as-obtained nanomaterials were examined by field emission scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and EIS. Concurrently, the electrocatalytic performance has been analyzed using cyclic voltammetry and amperometric measurements. The experimental results exhibit good electrochemical sensing performance toward the generated NO in NO2 - with a wide linear detection range of 1.0 μM to 1.0 mM with a correlation coefficient of 0.999 and a detection limit of 0.180 μM. In addition, the GaN nanowire-modified PGE surface showed high selectivity for the detection of NO as compared to other relevant biomolecules. This confirms that the PGE/GaN nanowire is a new promising electrochemical sensor for the sensitive detection of NO.

In Situ Hydrogel-Forming/Nitric Oxide-Releasing Wound Dressing for Enhanced Antibacterial Activity and Healing in Mice with Infected Wounds

The eradication of bacteria from wound sites and promotion of healing are essential for treating infected wounds. Nitric oxide (NO) is desirable for these purposes due to its ability to accelerate wound healing and its broad-spectrum antibacterial effects. We developed an in situ hydrogel-forming/NO-releasing powder dressing (NO/GP), which is a powder during storage and forms a hydrogel when applied to wounds, as a novel NO-releasing formulation to treat infected wounds. An NO/GP fine powder (51.5 μm) was fabricated by blending and micronizing S-nitrosoglutathione (GSNO), alginate, pectin, and polyethylene glycol (PEG). NO/GP remained stable for more than four months when stored at 4 or 37 °C. When applied to wounds, NO/GP absorbed wound fluid and immediately converted to a hydrogel. Additionally, wound fluid triggered a NO release from NO/GP for more than 18 h. The rheological properties of hydrogel-transformed NO/GP indicated that NO/GP possesses similar adhesive properties to marketed products (Vaseline). NO/GP resulted in a 6-log reduction in colony forming units (CFUs) of methicillin resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, which are representative drug-resistant gram-positive and -negative bacteria, respectively. The promotion of wound healing by NO/GP was demonstrated in mice with full-thickness wounds challenged with MRSA and P. aeruginosa. Thus, NO/GP is a promising formulation for the treatment of infected wounds.

Bioinorganics and Wound Healing

Wound dressings and the healing enhancement (increasing healing speed and quality) are two components of wound care that lead to a proper healing. Wound care today consists mostly of providing an optimal environment by removing waste and necrotic tissues from a wound, preventing infections, and keeping the wounds adequately moist. This is however often not enough to re-establish the healing process in chronic wounds; with the local disruption of vascularization, the local environment is lacking oxygen, nutrients, and has a modified ionic and molecular concentration which limits the healing process. This disruption may affect cellular ionic pumps, energy production, chemotaxis, etc., and will affect the healing process. Biomaterials for wound healing range from simple absorbents to sophisticated bioactive delivery vehicles. Often placing a material in or on a wound can change multiple parameters such as pH, ionic concentration, and osmolarity, and it can be challenging to pinpoint key mechanism of action. This article reviews the literature of several inorganic ions and molecules and their potential effects on the different wound healing phases and their use in new wound dressings.

Metabolites of the Nitric Oxide (NO) Pathway Are Altered and Indicative of Reduced NO and Arginine Bioavailability in Patients with Cardiometabolic Diseases Complicated with Chronic Wounds of Lower Extremities: Targeted Metabolomics Approach (LC-MS/MS)

OBJECTIVE

The status of metabolites of the nitric oxide (NO) pathway in patients with chronic wounds in the course of cardiometabolic diseases is largely unknown. Yet arginine supplementation and citrulline supplementation as novel therapeutic modalities aimed at increasing NO are tested.

MATERIAL AND METHODS

Targeted metabolomics approach (LC-MS/MS) was applied to determine the concentrations of L-arginine, L-citrulline, asymmetric and symmetric dimethylarginines (ADMA and SDMA), and arginine/ADMA and arginine/SDMA ratios as surrogate markers of NO and arginine availability in ulnar and femoral veins, representing systemic and local levels of metabolites, in patients with chronic wounds in the course of cardiometabolic diseases (n = 59) as compared to patients without chronic wounds but with similar cardiometabolic burden (n = 55) and healthy individuals (n = 88).

RESULTS

Patients with chronic wounds had significantly lower systemic L-citrulline and higher ADMA and SDMA concentrations and lower L-arginine/ADMA and L-arginine/SDMA as compared to healthy controls. The presence of chronic wounds in patients with cardiometabolic diseases was associated with decreased L-arginine but with increased L-citrulline, ADMA, and SDMA concentrations and decreased L-arginine/ADMA and L-arginine/SDMA. Serum obtained from the ulnar and femoral veins of patients with chronic wounds differed by L-arginine concentrations and L-arginine/SDMA ratio, both lower in the femoral vein. Wound etiology affected L-citrulline and SDMA concentrations, lower and higher, respectively, in patients with venous stasis, and the L-arginine/SDMA ratio-lower in venous stasis. The wound type affected L-arginine/ADMA and citrulline-lower in patients with ulcerations or gangrene. IL-6 was an independent predictor of L-arginine/ADMA, VEGF-A of ADMA, G-CSF of L-arginine/SDMA, and GM-CSF of L-citrulline and SDMA.

CONCLUSION

Chronic wounds in the course of cardiometabolic diseases are associated with reduced NO and arginine availability due to ADMA and SDMA accumulation rather than arginine deficiency, not supporting its supplementation. Wound character seems to affect NO bioavailability and wound etiology-arginine bioavailability. Arginine concentration and its availability are more markedly reduced at the local level than the systemic level.

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.

Cellular and physiological upregulation of inducible nitric oxide synthase, arginase, and inducible cyclooxygenase in wound healing

Wound repair is regulated by overlapping cellular, physiological and biochemical events. Prostaglandins and nitric oxide have been a focus for inflammation research particularly since the discovery of their inducible isoforms nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Study of the cellular expression of iNOS and COX-2 and arginase which competes with iNOS for its substrate, in an in vivo model of wound healing could reveal important roles for these enzymes in the physiological progression of wound repair. Adult male rats received full thickness dermal wounds which were harvested at different times. Protein levels and activities of the enzymes were assessed by western blot and biochemical assays respectively. The cellular distribution and the colocalization were assessed by immunostaining. The protein levels and activities of iNOS, arginase, and COX-2 increased only during the inflammatory phase of wound. Immunocytochemistry showed that the three enzymes were coexpressed and the main cellular source was inflammatory cells mainly macrophages. iNOS was induced at the wound site and was the earliest to increase significantly (p < 0.05) for only up to 3 days postwounding. However, arginase and COX-2 significant ( p < 0.05) upregulation started at a later time points and continued for up to 14 days postwounding. Therefore iNOS, compared with arginase and COX-2, showed a temporal difference in expression during wound healing which could be explained by their products being required at different stages of the healing process. The coordinated expression of the three enzymes at different time points could account for the physiological progression of the healing process.

Therapeutic strategies for enhancing angiogenesis in wound healing

The enhancement of wound healing has been a goal of medical practitioners for thousands of years. The development of chronic, non-healing wounds is a persistent medical problem that drives patient morbidity and increases healthcare costs. A key aspect of many non-healing wounds is the reduced presence of vessel growth through the process of angiogenesis. This review surveys the creation of new treatments for healing cutaneous wounds through therapeutic angiogenesis. In particular, we discuss the challenges and advancement that have been made in delivering biologic, pharmaceutical and cell-based therapies as enhancers of wound vascularity and healing.

PEI/NONOates-doped PLGA nanoparticles for eradicating methicillin-resistant Staphylococcus aureus biofilm in diabetic wounds via binding to the biofilm matrix

Wounds infected with methicillin-resistant Staphylococcus aureus (MRSA) biofilm represent a high risk in patients with diabetes. Nitric oxide (NO) has shown promise in dispersing biofilm and wound healing. For an effective treatment of MRSA biofilm-infected wounds, however, NO needs to be supplied to the biofilm matrix in a sustainable manner due to a short half-life and limited diffusion distance of NO. In this study, polyethylenimine/diazeniumdiolate (PEI/NONOate)-doped PLGA nanoparticles (PLGA-PEI/NO NPs) with an ability to bind to the biofilm matrix are developed to facilitate the NO delivery to MRSA biofilm-infected wound. In simulated wound fluid, PLGA-PEI/NO NPs show an extended NO release over 4 days. PLGA-PEI/NO NPs firmly bind to the MRSA biofilm matrix, resulting in a greatly enhanced anti-biofilm activity. Moreover, PLGA-PEI/NO NPs accelerate healing of MRSA biofilm-infected wounds in diabetic mice along with complete biofilm dispersal and reduced bacterial burden. These results suggest that the biofilm-binding NO-releasing NPs represent a promising NO delivery system for the treatments of biofilm-infected chronic wounds.

Enhancing Microcirculation on Multitriggering Manner Facilitates Angiogenesis and Collagen Deposition on Wound Healing by Photoreleased NO from Hemin-Derivatized Colloids

A deficiency of nitric oxide (NO) supply has been found to impair wound healing. The exogenous topical delivery of NO is a promising approach to enhance vasodilation and stimulate angiogenesis and collagen deposition. In this study, the CN groups on the surface of Prussian blue (PB) nanocubes were carefully reduced to -CH₂-NH₂ to conjugate with COOH group of hemin consisting of a Fe-porphyrin structure with strong affinity toward NO. Accordingly, the NO gas was able to coordinate to hemin-modified PB nanocubes. The hemin-modified PB carrying NO (PB-NO) can be responsible to near-infrared (NIR) light (808 nm) exposure to induce the thermo-induced liberation of NO based on the light-to-heat transformation property of PB nanocubes. The NO supply on the incisional wound sites can be readily topically dropped the colloidal solution of PB-NO for receiving NIR light irradiation. The enhanced blood flow was in a controllable manner whenever the wound sites containing PB-NO received NIR light irradiation. The promotion of blood perfusion following the on-demand multidelivery of NO has effectively facilitated the process of wound closure to enhance angiogensis and collagen deposition.

A bioactive exopolysaccharide from marine bacteria Alteromonas sp. PRIM-28 and its role in cell proliferation and wound healing in vitro

Marine bacteria secrete exopolysaccharides (EPS) with unique structural and functional properties and serve as a source of newer bioactive biopolymers. This study reports an EPS produced by a marine bacterium identified as Alteromonas sp. PRIM-28 for its bioactivities. The EPS was characterised using standard methods and tested for its bioactivities using in vitro models. EPS-A28 is an anionic heteropolysaccharide with a molecular weight of 780 kDa and exists as triple helical structure in aqueous solution. Monosaccharide composition is mannuronic acid, glucose and N-acetyl glucosamine repeating units in the ratio 1:3.67:0.93. The FT-IR spectra showed the presence of sulphate, phosphate and uronic acid residues. The thermal analysis showed partial degradation of the EPS-A28 at 190 °C and 40% of residues were stable up to 800 °C. It showed biocompatibility and induced proliferation and migration of dermal fibroblasts (HDF) and keratinocytes. EPS-A28 could increase the S-phase of cell cycle. The proliferative property of the EPS-A28 was established by the increased expression of fibroblast proliferation marker (Ki-67) also its capability of binding to cell surface. It also induced nitric oxide and arginase synthesis in macrophages. These findings suggest that EPS-A28 can be potentially used as a multifunctional bioactive polymer in wound care.

Plasma cupping induces VEGF expression in skin cells through nitric oxide-mediated activation of hypoxia inducible factor 1

Despite a long history, the clinical efficacy of cupping therapy is still under debate. This is likely due to the lack of direct evidence for the biological actions of cupping, since the short exposure of cells to vacuum condition rarely has affects cellular activity. In this study, the medicinal properties of a recent medical technology, non-thermal plasma, were added to classical cupping and designated as 'plasma cupping' (PC). In our results, the plasma-generating efficacy was increased under a cupping-like semi-vacuum condition (410 Torr) rather than normal atmospheric pressure (760 Torr). Notably, while cupping rarely affects the angiogenic factor vascular-endothelial growth factor (VEGF)-A, the PC treatment on HaCaT human keratinocytes significantly induced the expression of VEGF-A. The increased expression of the VEGF-A gene after the PC treatment was expected to be a result of PC-mediated ERK protein activation. The PC-mediated activation of ERK was essential for the activity of hypoxia inducible factor (HIF) 1 alpha, which is responsible for the PC-mediated expression of VEGF-A. The PC mediated increase of NO in the media was thought as a main reason for the elevated HIF-1 protein activity. In addition to the angiogenesis-promoting action of PC, it also showed anti-inflammatory activity by reducing TNF-α-mediated IL-1β and IL-6 expression. Taken together, this study indicates the potential for PC that could enhance the clinical efficacy of cupping by adding the effects of non-thermal plasma to traditional cupping.

Poly(DL-Lactide-co-ε-Caprolactone)/Poly(Acrylic Acid) Composite Implant for Controlled Delivery of Cationic Drugs

Poly(DL-lactide-co-ε-caprolactone)/poly(acrylic acid) implantable composite reservoirs for cationic drugs are synthesized by sequentially applying photoirradiation and liquid phase inversion. The chemical composition and microstructure of reservoirs are characterized with Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and scanning electron microscopy (SEM), respectively. Drug loading and release properties are investigated using methylene blue as the drug model. Biocompatibility of reservoirs is examined through a series of in vitro tests and an in vivo experiment of subcutaneous implantation in Dark Agouti rats. Reservoirs show good ion-exchange capacity, high water content, and fast reversible swelling with retained geometry. Results of drug loading and release reveal excellent loading efficiency and diffusion-controlled release during 2 weeks. Biocompatibility tests in vitro demonstrate the lack of implant proinflammatory potential and hindered adhesion of L929 cells on the implant surface. Implants exhibit low acute toxicity and elicit a normal acute foreign body reaction that reaches the early stages of fibrous capsule formation after 7 days.

Investigative Study on Nitric Oxide Production in Human Dermal Fibroblast Cells under Normal and High Glucose Conditions

Diabetic foot ulcers (DFU) are a major health problem associated with diabetes mellitus. Impaired nitric oxide (NO) production has been shown to be a major contributor to the dysregulation of healing in DFU. The level of impairment is not known primarily due to challenges with measuring NO. Herein, we report the actual level of NO produced by human dermal fibroblasts cultured under normal and high glucose conditions. Fibroblasts produce the extracellular matrix, which facilitate the migration of keratinocytes to close wounds. The results show that NO production was significantly higher in normal glucose compared to high glucose conditions. The real-time NO detected was compared to the nitrite present in the culture media and there was a direct correlation between real-time NO and nitrite in normal glucose conditions. However, real-time NO detection and nitrite measurement did not correlate under high glucose conditions. The inducible nitric oxide synthase (iNOS) enzyme responsible for NO production was upregulated in normal and high glucose conditions and the proliferation rate of fibroblasts was not statistically different in all the treatment groups. Relying only on nitrite to assess NO production is not an accurate determinant of the NO present in the wound bed in pathological states such as diabetes mellitus.

Host-microbiome interactions and recent progress into understanding the biology of acne vulgaris

Acne is one of the most common skin diseases worldwide and results in major health care costs and significant morbidity to severely affected individuals. However, the pathophysiology of this disorder is not well understood. Host-microbiome interactions that affect both innate and adaptive immune homeostasis appear to be a central factor in this disease, with recent observations suggesting that the composition and activities of the microbiota in acne is perturbed. Staphylococcus epidermidis and Cutibacterium acnes (C. acnes; formerly Propionibacterium acnes) are two major inhabitants of the skin that are thought to contribute to the disease but are also known to promote health by inhibiting the growth and invasion of pathogens. Because C. acnes is ubiquitous in sebaceous-rich skin, it is typically labeled as the etiological agent of acne yet it fails to fulfill all of Koch's postulates. The outdated model of acne progression proposes that increased sebum production promotes over-proliferation of C. acnes in a plugged hair follicle, thereby driving inflammation. In contrast, growing evidence indicates that C. acnes is equally abundant in both unaffected and acne-affected follicles. Moreover, recent advances in metagenomic sequencing of the acne microbiome have revealed a diverse population structure distinct from healthy individuals, uncovering new lineage-specific virulence determinants. In this article, we review recent developments in the interactions of skin microbes with host immunity, discussing the contribution of dysbiosis to the immunobiology of acne and newly emerging skin microbiome-based therapeutics to treat acne.

Supramolecular poly(acrylic acid)/F127 hydrogel with hydration-controlled nitric oxide release for enhancing wound healing

Topical nitric oxide (NO) delivery has been shown to accelerate wound healing. However, delivering NO to wounds at appropriate rates and doses requires new biomaterial-based strategies. Here, we describe the development of supramolecular interpolymer complex hydrogels comprising PEO-PPO-PEO (F127) micelles embedded in a poly(acrylic acid) (PAA) matrix, with S-nitrosoglutathione (GSNO) molecules dissolved in the hydrophilic domain. We show that PAA:F127/GSNO hydrogels start releasing NO upon hydration at rates controlled by their rates of water absorption. SAXS measurements indicate that the supramolecular structure of the hydrogels retains long-range order domains of F127 micelles. The PAA/F1227 hydrogels displayed dense morphologies and reduced rates of hydration. The NO release rates remain constant over the first 200 min, are directly correlated with the hydration rates of the PAA:F127/GSNO hydrogels, and can be modulated in the range of 40 nmol/g h to 1.5 μmol/g h by changing the PAA:F127 mass ratio. Long-term NO-release profiles over 5 days are governed by the first-order exponential decay of GSNO, with half-lives in the range of 0.5-3.4 days. A preliminary in vivo study on full-thickness excisional wounds in mice showed that topical NO release from the PAA:F127/GSNO hydrogels is triggered by exudate absorption and leads to increased angiogenesis and collagen fiber organization, as well as TGF-β, IGF-1, SDF-1, and IL-10 gene expressions in the cicatricial tissue. In summary, these results suggest that hydration-controlled NO release from topical PAA:F127/GSNO hydrogels is a potential strategy for enhancing wound healing.

STATEMENT OF SIGNIFICANCE

The topical delivery of nitric oxide (NO) to wounds may provide significant beneficial results and represent a promising strategy to treat chronic wounds. However, wound dressings capable of releasing NO after application and allowing the modulation of NO release rates, demand new platforms. Here, we describe a novel strategy to overcome these challenges, based on the use of supramolecular poly(acrylic acid) (PAA):F127 hydrogels charged with the NO donor S-nitrosoglutathione (GSNO) from whereby the NO release can be triggered by exudate absorption and delivered to the wound at rates controlled by the PAA:F127 mass ratio. Preliminary in vivo results offer a proof of concept for this strategy by demonstrating increased angiogenesis; collagen fibers organization; and TGF-β, IGF-1, SDF-1, and IL-10 gene expressions in the cicatricial tissue after topical treatment with a PAA:F127/GSNO hydrogel.

Platinum nanoparticles: an avenue for enhancing the release of nitric oxide from S-nitroso-N-acetylpenicillamine and S-nitrosoglutathione

Nitric oxide (NO) is an endogenous bioregulator with established roles in diverse fields. The difficulty in the modulation of NO release is still a significant obstacle to achieving successful clinical applications. We report herein our initial work using electron spin resonance (ESR) spectroscopy to detect NO generated from S-nitroso-N-acetylpenicillamine (SNAP) and S-nitrosoglutathione (GSNO) donors catalyzed by platinum nanoparticles (Pt NPs, 3 nm) under physiological conditions. With ESR spectroscopy coupled with spin trapping and spin labeling techniques, we identified that Pt NPs can significantly promote the generation of NO from SNAP and GSNO under physiological conditions. A classic NO colorimetric detection kit was also employed to verify that Pt NPs truly triggered the release of NO from its donors. Pt NPs can act as promising delivery vehicles for on-demand NO delivery based on time and dosage. These results, along with the detection of the resulting disulfide product, were confirmed with mass spectrometry. In addition, cellular experiments provided a convincing demonstration that the triggered release of NO from its donors by Pt NPs is efficient in killing human cancer cells in vitro. The catalytic mechanism was elucidated by X-ray photo-electron spectroscopy (XPS) and ultra-high performance liquid chromatography/high-resolution mass spectrometry (UHPLC-HRMS), which suggested that Pt-S bond formation occurs in the solution of Pt NPs and NO donors. Identification of Pt NPs capable of generating NO from S-nitrosothiols (RSNOs) is an important step in harnessing NO for investigations into its clinical applications and therapies.

Catalytic selectivity of metallophthalocyanines for electrochemical nitric oxide sensing

The catalytic properties of metallophthalocyanine (MPc) complexes have long been applied to electrochemical sensing of nitric oxide (NO) to amplify sensitivity and reduce the substantial overpotential required for NO oxidation. The latter point has significant ramifications for in situ amperometric detection, as large working potentials oxidize biological interferents (e.g., nitrite, L-ascorbate, and carbon monoxide). Herein, we sought to isolate and quantify, for the first time, the selectivity benefits of MPc modification of glassy carbon electrodes. A series of the most catalytically active MPc complexes towards NO, including Fe(II)Pc, Co(II)Pc, Ni(II)Pc, and Zn(II)Pc, was selected and probed for NO sensing ability under both differential pulse voltammetry (DPV) and constant potential amperometry (CPA). Data from DPV measurements provided information with respect to MPc signal sensitivity amplification (~1.5×) and peak shifting (100-200 mV). Iron-Pc exerted the most specific catalytic activity towards NO over nitrite. Catalyst-enabled reduction of the working potential under CPA was found to improve selectivity for NO over high potential interferents, regardless of MPc. However, impaired selectivity against low potential interferents was also noted.

Wearable Technology for Chronic Wound Monitoring: Current Dressings, Advancements, and Future Prospects

Chronic non-healing wounds challenge tissue regeneration and impair infection regulation for patients afflicted with this condition. Next generation wound care technology capable of in situ physiological surveillance which can diagnose wound parameters, treat various chronic wound symptoms, and reduce infection at the wound noninvasively with the use of a closed loop therapeutic system would provide patients with an improved standard of care and an accelerated wound repair mechanism. The indicating biomarkers specific to chronic wounds include blood pressure, temperature, oxygen, pH, lactate, glucose, interleukin-6 (IL-6), and infection status. A wound monitoring device would help decrease prolonged hospitalization, multiple doctors' visits, and the expensive lab testing associated with the diagnosis and treatment of chronic wounds. A device capable of monitoring the wound status and stimulating the healing process is highly desirable. In this review, we discuss the impaired physiological states of chronic wounds and explain the current treatment methods. Specifically, we focus on improvements in materials, platforms, fabrication methods for wearable devices, and quantitative analysis of various biomarkers vital to wound healing progress.

Assessment of clinical effectiveness of haemoglobin spray as adjunctive therapy in the treatment of sloughy wounds

OBJECTIVE

To assess use of an adjunctive topical haemoglobin spray in the treatment of sloughy wounds.

METHOD

In addition to a standard wound care regimen, consecutive patients with sloughy wounds self-administered haemoglobin spray treatment twice a week until the wound was healed. All patients were followed-up for 26 weeks. Results were compared with a retrospective cohort of 100 consecutive patients, treated during the same period the previous year with standard wound care alone. Data were collected on wound characteristics including percentage of slough, exudate levels, wound pain, and wound size.

RESULTS

After 26 weeks, 94/100 patients (94%) treated with haemoglobin spray were completely healed compared with 63/100 control patients (63%). Positive results were evident as early as week one with 52% mean wound size reduction using the heamoglobin spray versus 11% in the retrospective control (p<0.001). At baseline, mean slough coverage was higher in the haemoglobin group, 58% versus 44% in the control group (p<0.001). By week four, mean slough coverage was 1% in the haemoglobin versus 29% in the control group (p<0.001). Reductions in exudate and pain levels (p<0.001) were also observed.

CONCLUSION

Overall, results of this evaluation showed the addition of adjunctive haemoglobin spray to standard wound care treatment achieved positive clinical outcomes for patients self-managing complicated sloughy wounds, by supporting reduction of wound exudate and slough within the complex multifaceted process of wound healing.

Electroactive biomaterials: Vehicles for controlled delivery of therapeutic agents for drug delivery and tissue regeneration

Electrical stimulation for delivery of biochemical agents such as genes, proteins and RNA molecules amongst others, holds great potential for controlled therapeutic delivery and in promoting tissue regeneration. Electroactive biomaterials have the capability of delivering these agents in a localized, controlled, responsive and efficient manner. These systems have also been combined for the delivery of both physical and biochemical cues and can be programmed to achieve enhanced effects on healing by establishing control over the microenvironment. This review focuses on current state-of-the-art research in electroactive-based materials towards the delivery of drugs and other therapeutic signalling agents for wound care treatment. Future directions and current challenges for developing effective electroactive approach based therapies for wound care are discussed.

Histopathological and Inflammatory Features of Chronically Discharging Open Mastoid Cavities: Secondary Analysis of a Randomized Clinical Trial

Importance

Many patients with an open radical mastoid cavity experience therapy-resistant otorrhea. Little is known about the underlying histopathological substrate of unstable cavities and the correlation with treatment failure.

Objective

To study the histopathological and inflammatory features of chronically discharging open radical mastoid cavities and the influence of different treatments.

Design, Setting, and Participants

This secondary analysis of a randomized clinical trial was a histopathology study of tissue samples of a cohort of 30 patients with a chronically discharging open mastoid cavity. Samples were taken from the cavities, which were treated with either honey gel or conventional eardrops in a tertiary center between 2012 and 2013. Tissue staining was performed in May 2014; final computer analysis/correlation studies were performed in June 2016.

Main Outcomes and Measures

Differences of epithelial tissue coverage, infiltration of T cells (CD3, CD4, CD8) and macrophage (CD68, isoenzyme nitric oxide synthase, arginase 1) (sub-)populations, infection status, and the correlation with clinical presentation.

Results

There were 30 patients (24 [80%] male; mean [SD] age, 59 [14] years). Cavities were covered with either stratified squamous (keratinized) epithelium (n = 10), respiratory columnar epithelium (n = 9), or granulation tissue (n = 10). The presence of respiratory epithelium was associated with lower treatment success (posttreatment VAS improvement of 3.1 [95% CI, 0.5 to 5.8] for discomfort and 3.6 [95% CI, 0.2 to 6.9] for otorrhea in the group with granulation tissue coverage vs 4.9 [95% CI, 0.2 to 9.6] and 5.8 [95% CI, -0.1 to 11.6] in the group with squamous [keratinized] epithelium coverage and 1.4 [95% CI, -1.2 to 4.1] and 2.5 [95% CI, -1.3 to 6.2] in the group with respiratory columnar epithelium coverage). In all 3 tissue types of cavity-covering tissues, T-cell infiltrates consisted of helper T cells and cytotoxic T cells, together with a lower number of macrophages. The immunopositivity for isoenzyme nitric oxide synthase and arginase 1 was high and not restricted to a macrophage subpopulation, but seen in various cell types. Inflammatory infiltrations varied strongly in all 3 tissue modalities.

Conclusions and Relevance

Discharging open mastoid cavities can be classified histologically into 3 different types, based on their coverage: squamous epithelium, respiratory epithelium, or granulation tissue. Treatment is less successful in cavities covered with respiratory epithelium, possibly explained by the status of bacterial infection and local immunological differences.

Nitric oxide release from a cucurbituril encapsulated NO-donor

The denitrosation of a S-nitrosothiol derivative, nitrosomercaptopyridine (SNO⁺), can be inhibited by incorporation into the cucurbit[7]uril cavity. Owing to the reversible character of host : guest complexation, SNO⁺ can be expelled from the host cavity through the application of a chemical stimulus allowing controlled nitric oxide release.