An innovative topical drug formulation for wound healing and infection treatment: in vitro and in vivo investigations of a povidone-iodine liposome hydrogel

Status and Future Scope of Soft Nanoparticles-Based Hydrogel in Wound Healing

Wounds are alterations in skin integrity resulting from any type of trauma. The healing process is complex, involving inflammation and reactive oxygen species formation. Therapeutic approaches for the wound healing process are diverse, associating dressings and topical pharmacological agents with antiseptics, anti-inflammatory, and antibacterial actions. Effective treatment must maintain occlusion and moisture in the wound site, suitable capacity for the absorption of exudates, gas exchange, and the release of bioactives, thus stimulating healing. However, conventional treatments have some limitations regarding the technological properties of formulations, such as sensory characteristics, ease of application, residence time, and low active penetration in the skin. Particularly, the available treatments may have low efficacy, unsatisfactory hemostatic performance, prolonged duration, and adverse effects. In this sense, there is significant growth in research focusing on improving the treatment of wounds. Thus, soft nanoparticles-based hydrogels emerge as promising alternatives to accelerate the healing process due to their improved rheological characteristics, increased occlusion and bioadhesiveness, greater skin permeation, controlled drug release, and a more pleasant sensory aspect in comparison to conventional forms. Soft nanoparticles are based on organic material from a natural or synthetic source and include liposomes, micelles, nanoemulsions, and polymeric nanoparticles. This scoping review describes and discusses the main advantages of soft nanoparticle-based hydrogels in the wound healing process. Herein, a state-of-the-art is presented by addressing general aspects of the healing process, current status and limitations of non-encapsulated drug-based hydrogels, and hydrogels formed by different polymers containing soft nanostructures for wound healing. Collectively, the presence of soft nanoparticles improved the performance of natural and synthetic bioactive compounds in hydrogels employed for wound healing, demonstrating the scientific advances obtained so far.

Local Drug Delivery Strategies towards Wound Healing

A particular biological process known as wound healing is connected to the overall phenomena of growth and tissue regeneration. Several cellular and matrix elements work together to restore the integrity of injured tissue. The goal of the present review paper focused on the physiology of wound healing, medications used to treat wound healing, and local drug delivery systems for possible skin wound therapy. The capacity of the skin to heal a wound is the result of a highly intricate process that involves several different processes, such as vascular response, blood coagulation, fibrin network creation, re-epithelialisation, collagen maturation, and connective tissue remodelling. Wound healing may be controlled with topical antiseptics, topical antibiotics, herbal remedies, and cellular initiators. In order to effectively eradicate infections and shorten the healing process, contemporary antimicrobial treatments that include antibiotics or antiseptics must be investigated. A variety of delivery systems were described, including innovative delivery systems, hydrogels, microspheres, gold and silver nanoparticles, vesicles, emulsifying systems, nanofibres, artificial dressings, three-dimensional printed skin replacements, dendrimers and carbon nanotubes. It may be inferred that enhanced local delivery methods might be used to provide wound healing agents for faster healing of skin wounds.

Antibacterial biomaterials for skin wound dressing

Bacterial infection and the ever-increasing bacterial resistance have imposed severe threat to human health. And bacterial contamination could significantly menace the wound healing process. Considering the sophisticated wound healing process, novel strategies for skin tissue engineering are focused on the integration of bioactive ingredients, antibacterial agents included, into biomaterials with different morphologies to improve cell behaviors and promote wound healing. However, a comprehensive review on anti-bacterial wound dressing to enhance wound healing has not been reported. In this review, various antibacterial biomaterials as wound dressings will be discussed. Different kinds of antibacterial agents, including antibiotics, nanoparticles (metal and metallic oxides, light-induced antibacterial agents), cationic organic agents, and others, and their recent advances are summarized. Biomaterial selection and fabrication of biomaterials with different structures and forms, including films, hydrogel, electrospun nanofibers, sponge, foam and three-dimension (3D) printed scaffold for skin regeneration, are elaborated discussed. Current challenges and the future perspectives are presented in this multidisciplinary field. We envision that this review will provide a general insight to the elegant design and further refinement of wound dressing.

Insightful exploring of advanced nanocarriers for the topical/transdermal treatment of skin diseases

Dermatological products constitute a big segment of the pharmaceutical market. From conventional products to more advanced ones, a wide variety of dosage forms have been developed till current date. A representative of the advanced delivery means is carrier-based systems, which can load large number of drugs for treatment of dermatological diseases, or simply for cosmeceutical purposes. To make them more favorable for topical delivery, further incorporation of these carriers in a topical vehicle, such as gels or creams is made. Therefore in this review article, an overview is compiled of the most commonly encountered novel carrier based topical delivery systems; namely lipid based (nanoemulsions, microemulsions, solid lipid nanoparticles [SLNs] and nanostructured lipid carriers [NLCs]), and vesicular carriers (non-deformable, such as liposomes, niosomes, emulsomes and cerosomes, and deformable, such as transfersomes, ethosomes, transethosomes, and penetration enhancer vesicles), with special emphasis on those loaded in a secondary gel vehicle. A special focus was made on the commonly encountered dermatological diseases, such as bacterial and fungal infections, psoriasis, dermatitis, eczema, vitiligo, oxidative damage, aging, alopecia, and skin cancer.

Functional Hydrogels as Wound Dressing to Enhance Wound Healing

Hydrogels, due to their excellent biochemical and mechnical property, have shown attractive advantages in the field of wound dressings. However, a comprehensive review of the functional hydrogel as a wound dressing is still lacking. This work first summarizes the skin wound healing process and relates evaluation parameters and then reviews the advanced functions of hydrogel dressings such as antimicrobial property, adhesion and hemostasis, anti-inflammatory and anti-oxidation, substance delivery, self-healing, stimulus response, conductivity, and the recently emerged wound monitoring feature, and the strategies adopted to achieve these functions are all classified and discussed. Furthermore, applications of hydrogel wound dressing for the treatment of different types of wounds such as incisional wound and the excisional wound are summarized. Chronic wounds are also mentioned, and the focus of attention on infected wounds, burn wounds, and diabetic wounds is discussed. Finally, the future directions of hydrogel wound dressings for wound healing are further proposed.

Therapy of infected wounds: overcoming clinical challenges by advanced drug delivery systems

In recent years, the incidence of infected wounds is steadily increasing, and so is the clinical as well as economic interest in effective therapies. These combine reduction of pathogen load in the wound with general wound management to facilitate the healing process. The success of current therapies is challenged by harsh conditions in the wound microenvironment, chronicity, and biofilm formation, thus impeding adequate concentrations of active antimicrobials at the site of infection. Inadequate dosing accuracy of systemically and topically applied antibiotics is prone to promote development of antibiotic resistance, while in the case of antiseptics, cytotoxicity is a major problem. Advanced drug delivery systems have the potential to enable the tailor-made application of antimicrobials to the side of action, resulting in an effective treatment with negligible side effects. This review provides a comprehensive overview of the current state of treatment options for the therapy of infected wounds. In this context, a special focus is set on delivery systems for antimicrobials ranging from semi-solid and liquid formulations over wound dressings to more advanced carriers such as nano-sized particulate systems, vesicular systems, electrospun fibers, and microneedles, which are discussed regarding their potential for effective therapy of wound infections. Further, established and novel models and analytical techniques for preclinical testing are introduced and a future perspective is provided.

Managing Diabetic Foot Ulcers: Pharmacotherapy for Wound Healing

Historically, there has been a scarcity of evidence-based topical therapy to hasten the healing of diabetic foot ulcers. But recently new evidence-based treatments have emerged from multicentre, randomised, controlled trials. This article highlights those trials, and describes the current pharmacological management of the diabetic foot ulcer and the advances that have been made in wound therapy to date. It provides an overview of topical and systemic pharmacotherapies in current use and those in development for future use in managing the diabetic foot. For each treatment, proposed mechanisms of action and evidence available to support their clinical use are presented. There is supporting randomised, controlled evidence for sucrose octasulfate in the treatment of neuro-ischaemic ulcers, and multi-layered patch of autologous leucocytes, platelets and fibrin in ulcers with or without ischaemia. There is also evidence for placentally derived products and for topical and systemic oxygen therapy in the healing of diabetic foot ulcers. Growth factors, bio-engineered tissues, stem cell therapy, gene therapy and peptide therapy also have some supporting evidence in the healing of diabetic foot ulcers. Nonsurgical debriding agents may be useful when the optimum approach of sharp debridement is not possible, and immunomodulators may be helpful for their antimicrobial effects, but robust data is still required to strengthen the case for general use. The review does not cover antimicrobials as their primary role are as anti-infectives and not in wound healing. The development of nanotechnology has created a means of prolonging the bioavailability of target molecules at the wound site, with the use of glass/hydrogel nanoparticles, polyethylene glycol and hyaluronic acid. Looking forward, novel therapies, including traction force-activated payloads, local delivery of short-interfering RNA and finally hydrogels incorporating bioactive agents or cells may provide possibilities for pharmacotherapy in the future.

Engineering Smart Targeting Nanovesicles and Their Combination with Hydrogels for Controlled Drug Delivery

Smart engineered and naturally derived nanovesicles, capable of targeting specific tissues and cells and delivering bioactive molecules and drugs into them, are becoming important drug delivery systems. Liposomes stand out among different types of self-assembled nanovesicles, because of their amphiphilicity and non-toxic nature. By modifying their surfaces, liposomes can become stimulus-responsive, releasing their cargo on demand. Recently, the recognized role of exosomes in cell-cell communication and their ability to diffuse through tissues to find target cells have led to an increase in their usage as smart delivery systems. Moreover, engineering "smarter" delivery systems can be done by creating hybrid exosome-liposome nanocarriers via membrane fusion. These systems can be loaded in naturally derived hydrogels to achieve sustained and controlled drug delivery. Here, the focus is on evaluating the smart behavior of liposomes and exosomes, the fabrication of hybrid exosome-liposome nanovesicles, and the controlled delivery and routes of administration of a hydrogel matrix for drug delivery systems.

Evaluation in broilers of aerosolized nanoparticles vaccine encapsulating imuno-stimulant and antigens of avian influenza virus/Mycoplasma gallisepticum

Background

The global prevalence of economic primary infection of poultry by H9N2 virus, including the Lineage A, panzootic group ME1, and associated with secondary infection by Mycoplasma gallisepticum (MG), is alarming to the sustainability of the poultry sector. This research evaluated in broilers the immunity and protection induced by aerosolization of liposomal nanoparticles vaccine, encapsulating antigens of H9N2 virus and MG, with or without the incorporation of Echinacea extract (EE) immuno-stimulant. Six different treatments (TRTs) of broilers were included in the experimental design, with three replicate pens/TRT and stocking of 20 day-old birds/replicate.

Results

The tracheobronchial washings of birds subjected to aerosolization of liposomal nanoparticles, encapsulating antigens of H9N2 and MG and EE had the highest significant mean levels of each of IgA and IgG specific to H9N2 and MG, associated with lowest tracheal MG colonization, tracheal H9N2 recovery, tracheal histopathologic lesions, mortality, and best performance in body weight and feed conversion compared to all other challenged birds allocated to different treatments (P < 0.05). However, the control broilers, free from challenge with MG and H9N2, had the lowest mortality and tracheal lesions, and the highest production performance.

Conclusion

The aerosolization of liposomal nanoparticles, encapsulating antigens of H9N2 and MG and EE resulted in enough local immunity for protection of broilers against infection, and in attaining the highest production performance in challenged birds. The potential implication of vaccinating with safe killed nanoparticle vaccines is of utmost importance to the global poultry sector.

Bactericidal and virucidal activity of ethanol and povidone-iodine

Ethanol and povidone‐iodine (PVP‐I) are important microbicides that inactivate bacteria and viruses. The present study provides a review of literature data on the concentration‐dependent bactericidal and virucidal activity of ethanol and PVP‐I in vitro. A systematic search was performed using the meta‐database for biomedicine PubMed. Eventually, 74 studies with original data on the reduction of bacterial and viral infectivity using in vitro tests were analyzed. A safe bactericidal effect of ethanol can be expected at concentrations between 60% and 85%, and the exposure times vary between ≤0.5 and ≥5 min. Within an exposure of up to 5 min, 80%–90% ethanol also exerts virucidal/low‐level activity, which includes its action against enveloped viruses plus adeno‐, noro‐, and rotaviruses. For PVP‐I, the best bactericidal and virucidal/high‐level effect is present at a concentration range of approx. 0.08%–0.9% depending on the free iodine concentration. The maximum exposure times are 5 min for bacteria and 60 min for viruses. The available data may help optimize the significant inactivation of bacteria and viruses in various areas. However, as the conditions in application practice can vary, concrete recommendations for the application can only be derived to a limited extent.

Therapeutic compression materials and wound dressings for chronic venous insufficiency: A comprehensive review

Chronic venous insufficiency (CVI) is a common disorder worldwide. Related pathophysiological mechanisms reportedly involve venous pooling and reduced venous return, leading to heaviness, aching, itchiness, tiredness, varicosities, pigmentation, and even lower limb ulceration. Approaches adopted to manage CVI at various stages of clinical-etiology-anatomy-pathophysiology include compression therapy, pharmacological treatment, ultrasound treatment, surgery, electrical or wireless microcurrent stimulation, and pulsed electromagnetic treatment. Among these, polymer-based therapeutic compression materials and wound dressings play increasingly key roles in treating all stages of CVI because of their unique physical, mechanical, chemical, and biological functions. However, the characteristics, working mechanisms, and effectiveness of these CVI treatment materials are not comprehensively understood. The present systematic review examines the structures, properties, types, and applications of various polymer-based compression materials and wound dressings used in prophylaxis and treatment of CVI. Existing problems, limitations, and future trends of CVI treatment materials are also discussed. This review could contribute to the design and application of new functional polymer materials and dressings to enhance the efficiency of CVI treatments, thereby facilitating patients' self-care ability and long-term health improvement.

A Bifunctional Adsorber Particle for the Removal of Hydrophobic Uremic Toxins from Whole Blood of Renal Failure Patients

Hydrophobic uremic toxins accumulate in patients with chronic kidney disease, contributing to a highly increased cardiovascular risk. The clearance of these uremic toxins using current hemodialysis techniques is limited due to their hydrophobicity and their high binding affinity to plasma proteins. Adsorber techniques may be an appropriate alternative to increase hydrophobic uremic toxin removal. We developed an extracorporeal, whole-blood bifunctional adsorber particle consisting of a porous, activated charcoal core with a hydrophilic polyvinylpyrrolidone surface coating. The adsorption capacity was quantified using analytical chromatography after perfusion of the particles with an albumin solution or blood, each containing mixtures of hydrophobic uremic toxins. A time-dependent increase in hydrophobic uremic toxin adsorption was depicted and all toxins showed a high binding affinity to the adsorber particles. Further, the particle showed a sufficient hemocompatibility without significant effects on complement component 5a, thrombin-antithrombin III complex, or thrombocyte concentration in blood in vitro, although leukocyte counts were slightly reduced. In conclusion, the bifunctional adsorber particle with cross-linked polyvinylpyrrolidone coating showed a high adsorption capacity without adverse effects on hemocompatibility in vitro. Thus, it may be an interesting candidate for further in vivo studies with the aim to increase the efficiency of conventional dialysis techniques.

Hydrogel-Based Strategies to Advance Therapies for Chronic Skin Wounds

Chronic skin wounds are the leading cause of nontraumatic foot amputations worldwide and present a significant risk of morbidity and mortality due to the lack of efficient therapies. The intrinsic characteristics of hydrogels allow them to benefit cutaneous healing essentially by supporting a moist environment. This property has long been explored in wound management to aid in autolytic debridement. However, chronic wounds require additional therapeutic features that can be provided by a combination of hydrogels with biochemical mediators or cells, promoting faster and better healing. We survey hydrogel-based approaches with potential to improve the healing of chronic wounds by reviewing their effects as observed in preclinical models. Topics covered include strategies to ablate infection and resolve inflammation, the delivery of bioactive agents to accelerate healing, and tissue engineering approaches for skin regeneration. The article concludes by considering the relevance of treating chronic skin wounds using hydrogel-based strategies.

Consensus on Wound Antisepsis: Update 2018

Wound antisepsis has undergone a renaissance due to the introduction of highly effective wound-compatible antimicrobial agents and the spread of multidrug-resistant organisms (MDROs). However, a strict indication must be set for the application of these agents. An infected or critically colonized wound must be treated antiseptically. In addition, systemic antibiotic therapy is required in case the infection spreads. If applied preventively, the Wounds-at-Risk Score allows an assessment of the risk for infection and thus appropriateness of the indication. The content of this updated consensus recommendation still largely consists of discussing properties of octenidine dihydrochloride (OCT), polihexanide, and iodophores. The evaluations of hypochlorite, taurolidine, and silver ions have been updated. For critically colonized and infected chronic wounds as well as for burns, polihexanide is classified as the active agent of choice. The combination 0.1% OCT/phenoxyethanol (PE) solution is suitable for acute, contaminated, and traumatic wounds, including MRSA-colonized wounds due to its deep action. For chronic wounds, preparations with 0.05% OCT are preferable. For bite, stab/puncture, and gunshot wounds, polyvinylpyrrolidone (PVP)-iodine is the first choice, while polihexanide and hypochlorite are superior to PVP-iodine for the treatment of contaminated acute and chronic wounds. For the decolonization of wounds colonized or infected with MDROs, the combination of OCT/PE is preferred. For peritoneal rinsing or rinsing of other cavities with a lack of drainage potential as well as the risk of central nervous system exposure, hypochlorite is the superior active agent. Silver-sulfadiazine is classified as dispensable, while dyes, organic mercury compounds, and hydrogen peroxide alone are classified as obsolete. As promising prospects, acetic acid, the combination of negative pressure wound therapy with the instillation of antiseptics (NPWTi), and cold atmospheric plasma are also subjects of this assessment.

Efficacy of Conventional and Liposomal Povidone-Iodine in Infected Mesh Skin Grafts: An Exploratory Study

Introduction

Infection is a major threat to wound healing and a leading cause of graft loss in patients undergoing meshed skin grafts (MSGs). Therefore, topical antisepsis is important in the overall treatment scheme.

Methods

An exploratory satellite group of 14 patients with infected MSGs were enrolled as part of a prospective, randomized, controlled, parallel-group, open-label, pilot Phase II study that investigated the efficacy and tolerability of 3% liposomal povidone–iodine hydrogel (PVP–ILH, Repithel^®; RepiGel^®) versus chlorhexidine gauze in non-infected MSGs. The satellite group included both patients with infected wound beds prior to grafting and patients with infection of a previously placed graft, with MSG sizes ranging from 50 to 1000 cm², who were randomized to treatment with (PVP–ILH) or 10% povidone–iodine ointment (Betaisodona^®; BETADINE^®). Medication was applied in a 2-mm layer and dressing changes with identical application of study medication took place daily. Wounds were evaluated by photoplanimetry, microbiologically and subjectively by patients and physicians.

Results

The results for the main study group have been reported previously. In the satellite group, both PVP–ILH and povidone–iodine ointment performed remarkably well with respect to lowering the bacterial count and restoring wound healing, with different emphasis. Povidone–iodine ointment showed excellent antibacterial efficacy with no detectable microorganisms by Day 10, and rapid re-epithelialization (mean 90% by Day 6). PVP–ILH also demonstrated rapid re-epithelialization (mean 72% by Day 6) with a trend towards improved subjective measures of wound healing quality. Four patients (40%) receiving PVP–ILH experienced partial graft loss (10–15% of total MSG area); no patients in the povidone–iodine ointment group experienced graft loss.

Conclusion

Our results suggest that povidone–iodine ointment has a strong role in managing infected wounds, especially when a high concentration of povidone–iodine may be warranted, while PVP–ILH indicated similar beneficial results on markers of wound healing quality in larger infected wounds.

Trial Registration

The trial was conducted prior to mandatory registration of drug products, PVP–ILH represents a medicated device in the EU and many other countries.

Funding

Mundipharma Research GmbH & Co. KG.

Efficacy and tolerability of liposomal polyvinylpyrrolidone-iodine hydrogel for the localized treatment of chronic infective, inflammatory, dermatoses: an uncontrolled pilot study

Infection is common in many chronic, inflammatory skin conditions but is often difficult to treat, in part due to growing bacterial resistance to antibiotics. Liposomal polyvinyl-pyrrolidone (PVP)-iodine hydrogel has a unique mode of action, combining the antiseptic and anti-inflammatory actions of PVP-iodine with the drug delivery and moisturizing properties of liposomes. We investigated the utility of liposomal PVP-iodine to treat infective dermatoses. In this prospective, single-arm (uncontrolled), open-label Phase II pilot study, patients with acne vulgaris (n=30), atopic dermatitis (n=20), impetigo contagiosa (n=10), and rosacea (n=10) received PVP-iodine (3%) hydrogel for ≤4 weeks. Global Clinical Severity score improved for all dermatoses (range: 0.5 for acne vulgaris [p<0.001] to 1.0 for impetigo contagiosa [p=0.011]). Improvements in pain, quality of life, (Freiburg Life Quality Assessment), and Eczema Area and Severity Index scores were also seen. Treatment was well tolerated; most frequent adverse events were burning (14%) or itching (9%) sensations. Thus, liposomal PVP-iodine hydrogel has potential utility as an effective treatment for inflammatory skin conditions associated with bacterial colonization.

Heparin-Based Coacervate of FGF2 Improves Dermal Regeneration by Asserting a Synergistic Role with Cell Proliferation and Endogenous Facilitated VEGF for Cutaneous Wound Healing

Effective wound healing requires complicated, coordinated interactions and responses at protein, cellular, and tissue levels involving growth factor expression, cell proliferation, wound closure, granulation tissue formation, and vascularization. In this study, we develop a heparin-based coacervate consisting of poly(ethylene argininylaspartate digylceride) (PEAD) as a storage matrix, heparin as a bridge, and fibroblast growth factor-2 (FGF2) as a cargo (namely heparin-FGF2@PEAD) for wound healing. First, in vitro characterization demonstrates the loading efficiency and control release of FGF2 from the heparin-FGF2@PEAD coacervate. The following in vivo studies examine the wound healing efficiency of the heparin-FGF2@PEAD coacervate upon delivering FGF2 to full-thickness excisional skin wounds in vivo, in comparison with the other three control groups with saline, heparin@PEAD as vehicle, and free FGF2. Collective in vivo data show that controlled release of FGF2 to the wounds by the coacervate significantly accelerates the wound healing by promoting cell proliferation, stimulating the secretion of vascular endothelial growth factor (VEGF) for re-epithelization, collagen deposition, and granulation tissue formation, and enhancing the expression of platelet endothelial cell adhesion molecule (CD31) and alpha-smooth muscle actin (α-SMA) for blood vessel maturation. In parallel, no obvious wound healing effect is found for the control, vehicle, and free FGF2 groups, indicating the important role of the coavervate in the wound healing process. This work designs a suitable delivery system that can protect and release FGF2 in a sustained and controlled manner, which provides a promising therapeutic potential for topical treatment of wounds.

Characterisation and in vitro antimicrobial potential of liposome encapsulated silver ions against Candida albicans

Liposomes are biocompatible, biodegradable, controlled delivery systems with the ability to encapsulate both lipophilic and hydrophilic compounds, including metal ions. Liposome encapsulated Ag(+) (lipo-Ag(+)), prepared by reverse-phase evaporation, was used as a controlled delivery system against Candida albicans. Characterisation of the lipo-Ag(+) indicated that the multilamellar vesicles with diameters ranging between ≈ 0.5 and 5.0 μm showed potential as a controlled delivery system to consistently deliver Ag(+) to C. albicans. Results from inductively coupled plasma (ICP) analysis showed higher association of cell bound Ag(+) at 15 mins post exposure when compared to unencapsulated Ag(+). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicate detrimental effects of Ag(+) on C. albicans cell structure. These effects along with the ICP results also correlate with previously reported time kill experiment observations.

Vapor-based grafting of crosslinked poly(N-vinyl pyrrolidone) coatings with tuned hydrophilicity and anti-biofouling properties

Vapor-based one-step synthesis and grafting of poly(N-vinyl pyrrolidone) enable potent and durable anti-biofouling coatings with tailored structures.

Clinical and Antibiofilm Efficacy of Antimicrobial Hydrogels

Significance: Hydrogels have been shown to have a significant role to play in wound healing. Hydrogels are used to assist in the management of dry, sloughy, or necrotic wounds. However, recent scientific evidence has shown that biofilms delay wound healing and increase a wound propensity to infection. It is therefore essential that hydrogels incorporating antimicrobials demonstrate efficacy on biofilms. Consequently, it is the aim of this article to review the efficacy of hydrogels, incorporating antimicrobials, on wounds with specific reference to their efficacy on biofilms. Recent Advances: Technologies being developed for the management of wounds are rapidly expanding. In particularly next-generation hydrogels, incorporating copolymers, have been reported to enable the smart release of antimicrobials. This has led to the development of a more tailored patient-specific antimicrobial hydrogel therapy. Critical Issues: Evidence relating to the efficacy of hydrogels, incorporating antimicrobials, on biofilms within both the in vitro and in vivo environments is lacking. Future Direction: Studies that investigate the efficacy of antimicrobial hydrogel wound dressings on both in vivo and in vitro biofilms are important. However, there is a significant need for better and more reproducible in vivo biofilm models. Until this is possible, data generated from appropriate and representative in vitro models will help to assist researchers and clinicians in evaluating antimicrobial and antibiofilm hydrogel technology for the extrapolation of efficacy data relevant to biofilms present in the in vivo environment.

Delineating fibronectin bioadhesive micropatterns by photochemical immobilization of polystyrene and poly(vinylpyrrolidone)

Bioadhesive micropatterns, capable of laterally confining cells to a 2D lattice, have proven effective in simulating the in vivo tissue environment. They reveal fundamental aspects of the role of adhesion in cell mechanics, proliferation, and differentiation. Here we present an approach based on photochemistry for the fabrication of synthetic polymer micropatterns. Perfluorophenyl azide (PFPA), upon deep-UV exposure, forms a reactive nitrene capable of covalently linking to a molecule that is in close proximity. PFPA has been grafted onto a backbone of poly(allyl amine), which readily forms a self-assembled monolayer on silicon wafers or glass. A film of polystyrene was applied by spin-coating, and by laterally confining the UV exposure through a chromium-on-quartz photomask, monolayers of polymers could be immobilized in circular microdomains. Poly(vinylpyrrolidone) (PVP) was attached to the background to form a barrier to nonspecific protein adsorption and cell adhesion. Micropatterns were characterized with high-lateral-resolution time-of-flight secondary ion mass spectrometry (TOF-SIMS), which confirmed the formation of polystyrene domains within a PVP background. Fluorescence-microscopy adsorption assays with rhodamine-labeled bovine serum albumin demonstrated the nonfouling efficiency of PVP and, combined with TOF-SIMS, allowed for a comprehensive characterization of the pattern geometry. The applicability of the micropatterned platform in single-cell assays was tested by culturing two cell types, WM 239 melanoma cells and SaOs-2 osteoblasts, on micropatterned glass, either with or without backfilling of the patterns with fibronectin. It was demonstrated that the platform was efficient in confining cells to the fibronectin-backfilled micropatterns for at least 48 h. PVP is thus proposed as a viable, highly stable alternative to poly(ethylene glycol) for nonfouling applications. Due to the versatility of the nitrene-insertion reaction, the platform could be extended to other polymer pairs or proteins and the surface chemistry adapted to specific applications.

Liposomes: a new non-pharmacological therapy concept for seasonal-allergic-rhinoconjunctivitis

Mucosal barrier disorders play an important role in the pathomechanism of the allergic disease. A new approach for their treatment uses liposomes, which consist of phospholipids that make up 75% of the protective nasal surfactant layer. Our aim was to investigate the efficacy of liposomal-based therapy, as a comprehensive treatment alternative to guideline cromoglycate-based therapy, in the treatment of seasonal allergic rhinoconjunctivitis (SAR). We compared nasal and conjunctival symptom reduction with LipoNasal n nasal spray used as monotherapy (LNM), or LipoNasal n nasal spray and Tears Again eye spray combination therapy (LTC), against standard cromoglycate combination therapy (CGC). This prospective, controlled, open observational study was conducted monocentrically. According to their symptoms and preferences 72 patients with SAR were distributed in three equal groups. The study comprised two visits at an interval of 7 days. The efficacy was examined by daily documenting nasal and conjunctival symptom scores. The Nasal-Spray-Sensory-Scale and the Eye-Drops/Spray-Sensory-Scale were used to investigate the tolerability. Quality of life (QoL) was evaluated, using the RHINASTHMA QoL German adapted version. LNM achieved significant improvement in nasal (p < 0.001) and conjunctival symptoms (p = 0.050). The symptom reduction using CGC was equally significant. LTC led to significant nasal symptom relief (p = 0.045). QoL did not improve significantly in all groups (p > 0.05). The tolerability of all treatments was good and no adverse reactions were observed. In all treatment groups the improvement of the nasal and conjunctival symptom scores exceeds the minimal clinically important difference (MCID). The results demonstrate good tolerability and efficacy of non-pharmaceutical liposomal-based treatment (LipoNasal n and Tears Again), given as monotherapy or combination therapy, for nasal and conjunctival symptoms caused by SAR. This study indicates that liposomal-based treatment for SAR may be a comparable alternative to cromoglycate therapy. Further studies are needed to verify these findings.

Evaluation of the tissue toxicity of antiseptics by the hen's egg test on the chorioallantoic membrane (HETCAM)

Background

Antiseptics are frequently used for the prophylaxis and treatment of local infections of chronic wounds. Whereas local antiseptics in general have a positive effect on wound healing an uncritical use may impair wound healing due to toxic side effects.

Objective

We sought to assess the vascular irritation potential of different antiseptic solutions and ointments commonly used for short and long term application as a measure of tissue toxicity.

Method

The vascular irritation was evaluated by the hen's egg test (HET) on the chorioallantoic membrane (CAM). The effects on the vessels of a mucous membrane were directly assessed by stereomicroscopic observation in vivo.

Results

Severe CAM irritation was observed after short-term applications of 1% octenidin-2HCl (Octeni sept™), 72% isopropanol (Cutasept™), 0.35% chloroxylenol (Dettol™) and 10% PVP-I ointment (Betaisodona™). Medium irritations were observed for 10% PVP-I solution (Betaisodona™), 3% lysosomal PVP-I ointment (Repithel™), 1.8% cadexomer-iodine ointment (Iodosorb™) and 1% cadexomer-iodine pellets (Iodosorb™). Finally, slight irritations were observed for 1% PVP-I solution (Betaisodona™), 0.1% polyhexanid plus betain (Prontosan™) and 1% silver-sulfadiazine ointment (Flammazine™), whereas 0.04% polyhexanid solution (Lavanid™), washings from sterile maggots of Lucilia sericata and filtrated enzymes from Clostridium histolyticum (Iruxol-N™) showed no effects of irritation. In the long-term approaches, no vascular irritations were found for polyhexanid, washings from Lucilia sericata and enzyme filtrations from Clostridium histolyticum.

Conclusion

The vascular injuries caused by the studied antiseptics are an indirect indicator of their tissue toxicity. Strikingly, even therapeutic substances, which have been regarded as safe in their application for the treatment of chronic wounds in clinical studies, showed severe irritations on the CAM. We suggest that agents with no or low irritation potential on the CAM should be preferred in the clinical practice in order to obtain optimal results.

Thermally cross-linked PNVP films as antifouling coatings for biomedical applications

Protein repellent coatings are widely applied to biomedical devices in order to reduce the nonspecific adhesion of plasma proteins, which can lead to failure of the device. Poly(N-vinylpyrrolidone) (PNVP) is a neutral, hydrophilic polymer with outstanding antifouling properties often used in these applications. In this paper, we characterize for the first time a cross-linking mechanism that spontaneously occurs in PNVP films upon thermal annealing. The degree of cross-linking of PNVP films and their solubility in water can be tailored by controlling the annealing, with no need for additional chemical treatment or irradiation. The physicochemical properties of the cross-linked films were investigated by X-ray photoelectron spectroscopy, infrared spectroscopy, neutron and X-ray reflectometry, ellipsometry, and atomic force microscopy, and a mechanism for the thermally induced cross-linking based on radical formation was proposed. The treated films are insoluble in water and robust upon immersion in harsh acid environment, and maintain the excellent protein-repellent properties of unmodified PNVP, as demonstrated by testing fibrinogen and immunoglobulin G adsorption with a quartz crystal microbalance. Thermal cross-linking of PNVP films could be exploited in a wide range of biotechnological applications to give antifouling properties to objects of any size, essentially making this an alternative to high-tech surface modification techniques.

Virucidal efficacy of povidone-iodine-containing disinfectants

AIMS

The objective of this study was to evaluate virucidal efficacy of the commercially available povidone-iodine formulations Betaisodona solution and Betaseptic Mundipharma (Mundipharma).

METHODS AND RESULTS

The quantitative suspension test for virucidal testing of biocides according to the German guideline was used as method. The use of Betaisodona solution resulted in virucidal efficacy, corresponding to >or=10(4)-fold reduction in viral titre, against vaccinia virus, bovine viral diarrhoea virus and polyomavirus SV40 within 0.5 min and adenovirus type 5 within 3-5 min without and with organic load. For inactivation of the most resistant poliovirus type 1, a time interval of >or=60 min was needed. By contrast, Betaseptic Mundipharma inactivated significantly all model viruses for virucidal testing including poliovirus type 1 within 5 min independently from the addition of proteins.

CONCLUSIONS

Betaisodona solution shows a good efficacy against enveloped model viruses as well as against some nonenveloped human viruses, e.g. adenovirus and polyomavirus. Betaseptic Mundipharma has an excellent virucidal efficacy including the inactivation of the most resistent poliovirus type 1.

SIGNIFICANCE AND IMPACT OF THE STUDY

The findings of this study make Betaseptic Mundipharma suitable for virucidal disinfection of the skin within short time intervals.

Effect of Povidone-Iodine Liposome Hydrogel on Colonic Anastomosis

BACKGROUND

To evaluate the effect of povidone-iodine liposome hydrogel on colonic anastomosis.

METHODS

70 Wistar-Albino male rats were randomly divided into seven groups. The left colon was transected and end-to-end anastomosis was performed. PVP-I liposome hydrogel was applied around the anastomoses in groups 2 and 5. Colonic bursting pressures and tissue hydroxyproline contents were measured on postoperative days 3 and 7.

RESULTS

PVP-I application did not cause any difference in the bursting pressures on postoperative day 3, but anastomotic strength was significantly increased by the use of PVP-I on postoperative day 7. The use of PVP-I liposome hydrogel had no effect on the level of perianastomotic hydroxyproline on postoperative day 3 but had positive effects on postoperativeday 7.

CONCLUSIONS

We concluded that the beneficial effects of PVP-I liposome hydrogel might be due to the combination of broad-spectrum antimicrobial activity of PVP-I with the drug delivery properties and moisturizing molecular film effects of the liposome hydrogel.

[Local therapy of grade IIa burns: efficacy and tolerability of a new hydrosome wound gel for the local treatment of grade IIa burns as compared with silver sulfadiazine ointment]

BACKGROUND

A new hydrosome wound gel is based on a new mechanism of action. It contains hydrosomes that penetrate to the wound bed and supply the wound with phospholipids, which are identical to membrane phospholipids of human cells. In this manner it supports the proliferative processes during wound healing.

PATIENTS AND METHODS

In a randomized, controlled, intraindividual comparative study of 47 patients with grade IIa burns, the hydrosome wound gel was tested against silver sulfadiazine cream. Digital pictures of the burn wounds were taken daily, and the wounds were analyzed in terms of their reepithelization rate.

RESULTS

Wounds receiving the hydrosome wound gel healed 1.5-2 days faster than wounds treated with sulfadiazine cream (9.9+/-4.5 days vs. 11.3+/-4.9 days, p=0.015). In 66% of the patients, faster epithelization was observed with the hydrosome wound gel treatment. The hydrosome gel guaranteed secure prophylaxis against infection, and it was well tolerated and easy to apply.

CONCLUSION

In this study, the treatment of grade IIa burn wounds with hydrosome wound gel led to faster wound closure compared with treatment with sulfadiazine cream. Therefore, hydrosome gel represents a good alternative to sulfadiazine cream.

[Innovative wound therapy and skin substitutes for burns]

The success of modern burn therapy is based mainly on special burn intensive care, topical treatment, early eschar excision, and wound closure by immediate skin grafting or skin substitutes. This paper describes the current state of wound care and skin substitutes in burn therapy.

A Liposome Hydrogel With Polyvinyl-Pyrrolidone Iodine in the Local Treatment of Partial-Thickness Burn Wounds

Local treatment of burn injuries with conventional anti-infective preparations does not provide the moist environment that promotes fast wound healing. In a randomized controlled trial the effects of liposome polyvinyl-pyrrolidone-iodine (PVP-I) hydrogel, a novel formulation of PVP-I in a liposome hydrogel with high water-binding capacity, were investigated in 43 patients with partial-thickness burn wounds in an intraindividual comparison with a conventional silver-sulfadiazine cream. Treatment with liposome PVP-I hydrogel resulted in significantly faster complete healing of the burn wounds compared with silver-sulfadiazine cream (9.9 +/- 4.5 days versus 11.3 +/- 4.9; P < 0.015). The cosmetic result (smoothness, elasticity, appearance) was rated as excellent for 37.0% of study wounds with liposome PVP-I hydrogel compared with 13.0% of wounds treated with silver-sulfadiazine cream. Local tolerability was good; handling and change of dressing were rated as easy. Local treatment with liposome PVP-I hydrogel thus provides fast wound healing with a favorable cosmetic result.

Topical iodophor use in chronic wounds: a literature review

This study aimed to do a review of the literature regarding the use of topic iodine and/or compounds in the treatment of chronic wounds. The clinical trials were searched in the Cochrane database. Fourteen (58.3%) among 24 studies fulfilled the inclusion criteria. The articles were analyzed regarding journal and study characteristics and classified into three groups: Iodine versus other topic agents (7/ 50%); Iodine versus different dressings (6/ 42.9%); Iodine versus without Iodine (1/ 7.1%). Favorable results for the use of Iodine or similar product occurred in 50% of the analyzed studies. Six out of 8 trials showed favorable results for healing and infection prevention/ treatment; 4 out of 5 were not favorable when the healing objective was investigated and 1 study for infection treatment showed no favorable result.

Evaluation of amino acids as mediators for the antibacterial activity of iodine-lithium-alpha-dextrin in vitro and in vivo

OBJECTIVES

The systemic therapeutic application of iodophores has not yet been accepted due to limited availability of safe and effective ionized iodine preparations. Here we evaluated the antibacterial activity of iodine-lithium-alpha-dextrin (ILalphaD) both in vitro and in vivo.

METHODS

The MIC values of ILalphaD against 189 bacterial isolates in various growth media and in vivo toxicity and protective efficacy of ILalphaD in preventing mortality of rats infected with Staphylococcus aureus were determined. The intracellular killing of S. aureus by neutrophils in the presence of ILalphaD and myeloperoxidase (MPO)-catalysed oxidation of iodide was also determined.

RESULTS

The MIC values of ILalphaD against 189 Gram-positive cocci and Gram-negative bacilli ranged between 124-512 mg/L in growth media and 6.2-12.5 mg/L in buffer solution, and were highly variable in the presence of amino acids. We observed protection of S. aureus-infected rats from death with significant reduction of bacterial growth in organs upon intravenous administration of ILalphaD at doses that are 4-12 times lower than maximal in vivo tolerability dose. Intracellular killing of S. aureus by neutrophils increased in the presence of ILalphaD probably due to MPO-catalysed oxidation of iodide into hypoiodous acid. The pattern of ILalphaD reaction with amino acids at different pH or halide ion content determined both the generation of long-lived secondary oxidants and antibacterial activity.

CONCLUSIONS

Systemic application of ILalphaD proved to be successful in the rat infection model by promoting host defence. Probable mechanisms are increased intracellular killing of bacteria by production of hypoiodous acid and iodamines as well as anti-inflammatory activity.

Evaluation of the antibacterial activity and toxicity of 2 new hydrogels: a pilot study

Wound bed preparation remains a very important issue in wound healing. To promote the production of granulation tissue, it is necessary to remove necrotic tissue and to control infection. Necrotic tissue may be removed using a hydrogel preparation. Flaminal and Flaminal Hydro (Flen Pharma, Belgium) are 2 new hydroactive colloid gel dressings with state antibacterial properties. These properties are attributed to an enzymatic complex in their formulation. In the study described in this report, the antibacterial effects of Flaminal and Flaminal Hydro were confirmed in an in vitro as well as an in vivo setting. It was also demonstrated that Flaminal and Flaminal Hydro are not toxic to keratinocytes in vitro using an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] test.

PVP-iodine in hydrosomes and hydrogel--a novel concept in wound therapy leads to enhanced epithelialization and reduced loss of skin grafts

BACKGROUND

Moist wound treatment improves healing at a possibly increased risk of bacterial infection and many local antiseptics impair healing. A moist treatment modality with efficient antimicrobial activity would be desirable.

METHODS

In this monocentric, randomized, observer blinded, phase III study, a new hydrosome polyvinyl-pyrrolidone (PVP)-iodine preparation in hydrogel containing iodine in a 3% concentration (Repithel) was investigated for its effect on epithelialization in patients receiving meshed skin grafts. Grafts of 167 patients (donor site defects, burn wounds, or chronic defects) were dressed either with Repithel (n=83) covered with a gauze (Jelonet), or Jelonet-gauze only (n=84) until healing.

RESULTS

Grafts receiving Repithel healed significantly earlier (9.4 days versus 12.4 days; p<0.0001) and faster than controls as measured by neo-epithelialization of mesh holes between days 7 and 11 (91.2+/-22.8% versus 82.3%+/-28.6, p<0.0001). A subgroup analysis showed that the effects on grafted burn wounds (p=0.0042) and chronic defects (p<0.0001) was more significant than on donor sites. Also a higher take rate of grafts (p=0.0053) and a reduced loss of grafts was observed with Repithel treatment (8 grafts versus 20 grafts) (p=0.0063, respectively). Smokers had improved graft take (p=0.0069) and higher rate of epithelialization (p=0.0040) compared to smokers of the control group.

CONCLUSIONS

The results demonstrate significant clinical advantages of Repithel. This new local wound healing drug combines antisepsis and wound moisture efficiently resulting in significantly enhanced epithelialization, decreased transplant losses, and significantly improved healing especially in smokers.

Effect of Polyvinylpyrrolidone-Iodine Liposomal Hydrogel on Wound Microcirculation in SKH1-hr Hairless Mice

AIM

Polyvinylpyrrolidone-iodine liposomal hydrogel (PVP-ILH) is a hydrogel formulation based on polyvinylpyrrolidone-iodine (PVP-I) and liposomes. The beneficial effects of PVP-ILH on wound healing have been previously shown. The aim of this study was to investigate the effects of topically applied PVP-ILH on wound microcirculation.

MATERIALS AND METHODS

Experiments were performed on wounds in male SKH1-hr hairless mice (n = 48). Mice were randomized into five treatment groups: mice treated with polyacrylic acid (PAA) and PAA 1:10 as well as PVP-ILH and PVP-ILH 1:10. Mice treated with sodium chloride served as control. Immediately as well as 3, 7, and 14 days after wounding, intravital fluorescent microscopy (IFM) was performed to determine wound surface area and standard microcirculatory parameters.

RESULTS

Topically administered PVP-ILH reduced wound size significantly faster compared to controls. Standard microcirculatory parameters, e.g. functional capillary density (FCD) and plasma leakage, showed no differences. FCD increases in all groups after wound creation. Using PVP-ILH, a trend towards higher FCD was observed.

CONCLUSION

The wound model in hairless mice in combination with IFM is suitable to qualitatively assess wound microcirculation over a period of 2 weeks even after topical application of pigmented ointments. PVP-ILH showed a positive effect on dermal wound healing and wound microcirculation.

Repithel®: Removing the Barriers to Wound Healing

BACKGROUND

Various standardized and/or validated models exist to test wound healing products. This article discusses their usefulness in clinical practice.

OBJECTIVES

Major barriers to wound healing have been identified after intense interaction of research and practitioners. Although extensively tested, wound healing products are still associated with trial and error due to the high variability and complexity associated with the treatment of wounds. Therefore, the results of preclinical testing are compared and contrasted with clinical observations of a liposomal hydrogel containing 3% povidone-iodine (Repithel, PVP-ILH) to assess their expressiveness and to give the practitioner more guidance in application.

METHODS

Testing of PVP-ILH included physicochemical testing according to ISO norms, testing in in vitro and in vivo models. The obtained results are compared to the clinical profile of the obtained product in randomized controlled trials and ultimately expressive case studies.

RESULTS

PVP-ILH displays good local tolerance, the basis for use in sensitive and predamaged tissue. As observed in laboratory testing, it readily provides moisture and takes up limited amounts of moisture. This was also seen in the clinical testing, as the ability to keep wounds moist and incorporate a certain -- but not large -- amount of exudates. Clinical results also show clean, well-debrided wounds, an effect that (in the absence of an established model for wound cleansing) was traced to the hydrogel component carbomer.

DISCUSSION

Recent consensus advocates the concept of wound bed preparation as a systematic approach to removing barriers to healing (TIME). Based on the results, tissue (removing non-viable tissue and debris) and moisture (balance) can now be better understood, and infection/inflammation (control) and edge (progressing, non-advancing or undermining wound edges) are reviewed together with previously published data to assess all aspects potentially impeding wound healing.

CONCLUSION

PVP-ILH successfully removes barriers to wound healing, thus laying the foundation to high-quality wound closure. Results from many scientific disciplines can help the user to better understand a product, standardization of testing is the only way of making results comparable.

Bewährte und aktuelle Verfahren in der Wundheilung

Most chronic wounds are caused by arterial or venous vascular disease. Wound care is an interdisciplinary task and economic challenge. Numerous new wound dressings and treatment methods have been introduced recently. Basic research has enhanced our understanding of stimulation and inhibition of wound healing. Well-constructed clinical studies have shown some traditional approaches to be effective and others, less so. Successful wound healing requires treatment of the underlying disease as well as correction of local factors that may delay healing. The choice of dressings must be based on continuous re-assessment of the wound. Modern approaches for the most common types of chronic wounds, as well as options such as vacuum treatment and tissue-engineered skin are presented along with information on latest rules for reimbursement for wound care in Germany.