Nanocrystalline silver, gelatinases and the clinical implications

To Debride or Not to Debride: A Review of Wound Management for Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are immune-mediated skin reactions with high mortality as a result of severely compromised skin barrier function. Currently, there is no consensus on the topical management of these conditions. Some advocate for surgical debridement of affected skin as a means of preventing infection and facilitating reepithelialization with synthetic and biological wound coverage. Others prefer a conservative approach that relies on leaving the blistered skin in situ. A consensus is lacking, primarily due to the rarity of the disease and the lack of high-quality evidence supporting one particular form of management. The goal of this review is to explore and compare the two treatment approaches for SJS and TEN, namely conservative management and surgical debridement.

The Leptospermum scoparium (Mānuka)-Specific Nectar and Honey Compound 3,6,7-Trimethyllumazine (LepteridineTM) That Inhibits Matrix Metalloproteinase 9 (MMP-9) Activity

3,6,7-trimethyllumazine (Lepteridine™) is a newly discovered natural pteridine derivative unique to Mānuka (Leptospermum scoparium) nectar and honey, with no previously reported biological activity. Pteridine derivative-based medicines, such as methotrexate, are used to treat auto-immune and inflammatory diseases, and Mānuka honey reportedly possesses anti-inflammatory properties and is used topically as a wound dressing. MMP-9 is a potential candidate protein target as it is upregulated in recalcitrant wounds and intestinal inflammation. Using gelatin zymography, 40 μg/mL LepteridineTM inhibited the gelatinase activities of both pro- (22%, p < 0.0001) and activated (59%, p < 0.01) MMP-9 forms. By comparison, LepteridineTM exerted modest (~10%) inhibition against a chromogenic peptide substrate and no effect against a fluorogenic peptide substrate. These findings suggest that LepteridineTM may not interact within the catalytic domain of MMP-9 and exerts a negligible effect on the active site hydrolysis of small soluble peptide substrates. Instead, the findings implicate fibronectin II domain interactions by LepteridineTM which impair gelatinase activity, possibly through perturbed tethering of MMP-9 to the gelatin matrix. Molecular modelling analyses were equivocal over interactions at the S1' pocket versus the fibronectin II domain, while molecular dynamic calculations indicated rapid exchange kinetics. No significant degradation of synthetic or natural LepteridineTM in Mānuka honey occurred during simulated gastrointestinal digestion. MMP-9 regulates skin and gastrointestinal inflammatory responses and extracellular matrix remodelling. These results potentially implicate LepteridineTM bioactivity in Mānuka honey's reported beneficial effects on wound healing via topical application and anti-inflammatory actions in gastrointestinal disorder models via oral consumption.

Application of an instructive hydrogel accelerates re-epithelialization of xenografted human skin wounds

Poor quality (eg. excessive scarring) or delayed closure of skin wounds can have profound physical and pyschosocial effects on patients as well as pose an enormous economic burden on the healthcare system. An effective means of improving both the rate and quality of wound healing is needed for all patients suffering from skin injury. Despite wound care being a multi-billion-dollar industry, effective treatments aimed at rapidly restoring the skin barrier function or mitigating the severity of fibrotic scar remain elusive. Previously, a hydrogel conjugated angiopoietin-1 derived peptide (QHREDGS; Q-peptide) was shown to increase keratinocyte migration and improve wound healing in diabetic mice. Here, we evaluated the effect of this Q-Peptide Hydrogel on human skin wound healing using a mouse xenograft model. First, we confirmed that the Q-Peptide Hydrogel promoted the migration of adult human keratinocytes and modulated their cytokine profile in vitro. Next, utilizing our human to mouse split-thickness skin xenograft model, we found improved healing of wounded human epidermis following Q-Peptide Hydrogel treatment. Importantly, Q-Peptide Hydrogel treatment enhanced this wound re-epithelialization via increased keratinocyte migration and survival, rather than a sustained increase in proliferation. Overall, these data provide strong evidence that topical application of QHREDGS peptide-modified hydrogels results in accelerated wound closure that may lead to improved outcomes for patients.

Antibacterial Activity of Silver and Its Application in Dentistry, Cardiology and Dermatology

The problem of antimicrobial resistance is increasingly present and requires the discovery of new antimicrobial agents. Although the healing features of silver have been recognized since ancient times, silver has not been used due to newly discovered antibiotics. Thanks to technology development, a significant step forward has been made in silver nanoparticles research. Nowadays, silver nanoparticles are a frequent target of researchers to find new and better drugs. Namely, there is a need for silver nanoparticles as alternative antibacterial nanobiotics. Silver nanoparticles (AgNPs), depending on their size and shape, also have different antimicrobial activity. In addition to their apparent antibacterial activity, AgNPs can serve as drug delivery systems and have anti-thrombogenic, anti-platelet, and anti-hypertensive properties. Today they are increasingly used in clinical medicine and dental medicine. This paper presents silver antimicrobial activity and its use in dentistry, cardiology, and dermatology, where it has an extensive range of effects.

A Retrospective Study on the Use of Dermis Micrografts in Platelet-Rich Fibrin for the Resurfacing of Massive and Chronic Full-Thickness Burns

The coverage of massive burns still represents a big challenge, even if several strategies are to date available to deal with this situation. In this study, we describe the use of a combination of platelet-rich fibrin and micrograft spray-on skin in order to increase the yield of grafted cells in patients. We treated a total of five patients, of which two were affected by massive burns and three with chronic burn wounds. Briefly, autologous micrografts were obtained by Rigenera technology using a class I medical device called Rigeneracons. The micrografts were then combined with PRF and sprayed on the wound bed by a Spraypen. Before applying PRF/micrograft spray-on skin, the wound bed was covered with an Integra® dermal template, and the wounds were dressed with a layer of antimicrobial dressing applied directly over the silicone layer. When the silicone layer of the dermal template started showing signs of separation, the wound was considered ready for grafting. In all cases, we observed a fast and complete skin graft on average after 7-10 days by PRF/micrograft spray-on skin treatment. In particular, two patients with massive burns reported rapid reepithelialization, and three patients with chronic burn wounds, two of whom had failed skin grafts before the procedure, had complete wound healing within a week. In conclusion, the results showed in this study suggest that the use of PRF/micrograft spray-on skin represents a promising approach in the management of burns or chronic burn wounds.

Fabrication of biopolymer based nanocomposite wound dressing: evaluation of wound healing properties and wound microbial load

The aim of this study is to introduce natural-based polymers, chitosan and starch, to design a remedial nanocomposite, comprising of cerium oxide nanoparticles and silver nanoparticles, to investigate their effects in accelerating wound healing and in wound microbial load. Cerium oxide nanoparticles synthesized in starch solution added to the colloidal dispersion of synthesized silver nanoparticles in chitosan to make a three-component nanomaterial. Mice were anaesthetized and two parallel full-thickness round wounds were excised under aseptic conditions with the help of sterile dermal biopsy punch. Furthermore, effects of silver-chitosan and silver-cerium-chitosan nanocomposite had evaluated on rate of wound closure and collagen density and on microbial load of wound in full-thickness model. Results showed that both silver chitosan and silver-cerium-chitosan had significant impact on acceleration of wound closure and collagen content and on reduction of wound microbial load in comparison with control group, which was, received no treatments. However, the silver-cerium-chitosan nanocomposite is more potent than silver-chitosan group and control group in wound closure. The wound healing effects of silver-cerium-chitosan nanocomposite are due to unique features of its three components and this nanocomposite promises impressive remedies for clinical application.

Aspects of Nanomaterials in Wound Healing

Wound infections impose a remarkable clinical challenge that has a considerable influence on morbidity and mortality of patients, influencing the cost of treatment. The unprecedented advancements in molecular biology have come up with new molecular and cellular targets that can be successfully applied to develop smarter therapeutics against diversified categories of wounds such as acute and chronic wounds. However, nanotechnology-based diagnostics and treatments have achieved a new horizon in the arena of wound care due to its ability to deliver a plethora of therapeutics into the target site, and to target the complexity of the normal wound-healing process, cell type specificity, and plethora of regulating molecules as well as pathophysiology of chronic wounds. The emerging concepts of nanobiomaterials such as nanoparticles, nanoemulsion, nanofibrous scaffolds, graphene-based nanocomposites, etc., and nano-sized biomaterials like peptides/proteins, DNA/RNA, oligosaccharides have a vast application in the arena of wound care. Multi-functional, unique nano-wound care formulations have acquired major attention by facilitating the wound healing process. In this review, emphasis has been given to different types of nanomaterials used in external wound healing (chronic cutaneous wound healing); the concepts of basic mechanisms of wound healing process and the promising strategies that can help in the field of wound management.

Recent advancements in biopolymer and metal nanoparticle-based materials in diabetic wound healing management

Currently, diabetes mellitus (DM) accelerated diabetic foot ulcer (DFU) remains vivacious health problem related with delayed healing and high amputation rates which leads to enormous clinical obligation. Keeping in view of the foregoing, researchers have been made in their efforts to develop novel materials which accelerate delayed wound healing in the diabetic patient and reduce the adversative influences of DFUs. The most prominent materials used for the wound healing application have biocompatibility, low cytotoxicity, excellent biodegradable properties, and antimicrobial activity properties. Utilization of nanoparticles has emerged as a protruding scientific and technological revolution in controlling DFUs. Biopolymers in combination with bioactive nanoparticles having antimicrobial, antibacterial, and anti-inflammatory properties have great potential in wound care to enhance the healing process of diabetic wound infectious. Combination of antibacterial nanoparticles like silver nanoparticles (AgNPs), gold nanoparticles (AuNPs), copper nanoparticles (CuNPs) etc. with polymeric matrix could efficiently inhibit bacterial growth and at the same time fastens the healing process of a wound. This review briefed the recent development of different natural polymers and antibacterial nanoparticles to mitigate the diabetes mellitus based DFU.

Silver nanoparticles enhance wound healing in zebrafish (Danio rerio)

Silver nanoparticles (AgNPs) were successfully synthesized by a chemical reduction method, physico-chemically characterized and their effect on wound-healing activity in zebrafish was investigated. The prepared AgNPs were circular-shaped, water soluble with average diameter and zeta potential of 72.66 nm and -0.45 mv, respectively. Following the creation of a laser skin wound on zebrafish, the effect of AgNPs on wound-healing activity was tested by two methods, direct skin application (2 μg/wound) and immersion in a solution of AgNPs and water (50 μg/L). The zebrafish were followed for 20 days post-wounding (dpw) by visual observation of wound size, calculating wound healing percentage (WHP), and histological examination. Visually, both direct skin application and immersion AgNPs treatments displayed clear and faster wound closure at 5, 10 and 20 dpw compared to the controls, which was confirmed by 5 dpw histology data. At 5 dpw, WHP was highest in the AgNPs immersion group (36.6%) > AgNPs direct application group (23.7%) > controls (18.2%), showing that WHP was most effective in fish immersed in AgNPs solution. In general, exposure to AgNPs induced gene expression of selected wound-healing-related genes, namely, transforming growth factor (TGF-β), matrix metalloproteinase (MMP) -9 and -13, pro-inflammatory cytokines (IL-1β and TNF-α) and antioxidant enzymes (superoxide dismutase and catalase), which observed differentiation at 12 and 24 h against the control; but the results were not consistently significant, and many either reached basal levels or were down regulated at 5 dpw in the wounded muscle. These results suggest that AgNPs are effective in acceleration of wound healing and altered the expression of some wound-healing-related genes. However, the detailed mechanism of enhanced wound healing remains to be investigated in fish.

Exudate collection using wound sponges-An easy, non-invasive and reliable method to explore protease activities in ulcers

Proteases are important for wound healing, but in excessive amounts or left uncontrolled, they may cause healing impairment or other severe wound complications. Point-of-care testing for protease activities in wounds may be useful for monitoring the effectiveness of treatment, and for early identification of wounds that potentially fail to heal. Here we describe an easy, noninvasive method to collect wound fluid for evaluating the protease milieu of wounds. Wound fluids were collected using sterile sponges applied between wound surface and normal wound dressing. Wound fluid could be easily squeezed or centrifuged out of the sponges and was tested for gelatinase (MMP-2 and MMP-9) activities by gel zymography. In addition, we measured polymorphonuclear granulocyte elastase levels by ELISA. Both gelatinases were remarkably stable in sponge derived fluids, as no significant loss was observed even when samples were stored for 3 days at room temperature. Protease levels were highly diverse amongst patients and, in some cases, showed substantial variations in the course of the treatment. The here described wound sponge approach represents a patient-friendly and reliable method to collect wound fluid for evaluating wound healing relevant biomarkers, such as matrix metalloproteinases.

Bioactive Nanocomposites for Tissue Repair and Regeneration: A Review

This review presents scientific findings concerning the use of bioactive nanocomposites in the field of tissue repair and regeneration. Bioactivity is the ability of a material to incite a specific biological reaction, usually at the boundary of the material. Nanocomposites have been shown to be ideal bioactive materials due the many biological interfaces and structures operating at the nanoscale. This has resulted in many researchers investigating nanocomposites for use in bioapplications. Nanocomposites encompass a number of different structures, incorporating organic-inorganic, inorganic-inorganic and bioinorganic nanomaterials and based upon ceramic, metallic or polymeric materials. This enables a wide range of properties to be incorporated into nanocomposite materials, such as magnetic properties, MR imaging contrast or drug delivery, and even a combination of these properties. Much of the classical research was focused on bone regeneration, however, recent advances have enabled further use in soft tissue body sites too. Despite recent technological advances, more research is needed to further understand the long-term biocompatibility impact of the use of nanoparticles within the human body.

Fabrication of transparent quaternized PVA/silver nanocomposite hydrogel and its evaluation as an antimicrobial patch for wound care systems

Grafting of quaternary nitrogen atoms into the backbone of polymer is an efficient way of developing new generation antimicrobial polymeric wound dressing. In this study, an elastic, non-adhesive and antimicrobial transparent hydrogel based dressing has been designed, which might be helpful for routine observation of wound area without removing the dressing material along with maintaining a sterile environment for a longer period of time. Green synthesized silver nanoparticles have been loaded into the quaternized PVA hydrogel matrix to improve its antimicrobial property. Silver nanoparticles loaded quaternized PVA hydrogel showed enhanced mechanical and swelling properties compared to native quaternized PVA hydrogel. Release kinetics evaluated by atomic absorption spectroscopy revealed that the release mechanism of silver nanoparticles from the hydrogel follows Fickian diffusion. Antimicrobial efficacy of the hydrogels was evaluated by disk diffusion test on Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. After 96 h of release in phosphate buffer, the growth inhibition zone created by silver nanoparticless loaded quaternized PVA hydrogel is comparable to that created by ampicillin. These observations assert that the silver nanoparticles loaded quaternized PVA hydrogel acts as a reservoir of silver nanoparticles, which helps in maintaining a sterile environment for longer time duration by releasing Ag nanocrystallite in sustained manner.

Nanomaterials as a game changer in the management and treatment of diabetic foot ulcers

Nanoengineered biomaterials have tremendously improved the range of tools utilized for the control of as well as acceleration of healing of diabetic foot ulcers (DFU) over the last few decades.

Acticoat™ stimulates inflammation, but does not delay healing, in acute full-thickness excisional wounds

Acticoat™ has antimicrobial and anti-inflammatory effects which aid wound healing. However, in vitro studies indicate that Acticoat™ is cytotoxic and clinical and in vivo studies suggest that it may delay healing in acute wounds. Therefore, this study investigated the effects of Acticoat™ on healing in acute full-thickness excisional wounds. Using a porcine model, healing was assessed on days 3, 6, 9 and 15 post-wounding. Five wounds dressed with Acticoat™ and five wounds dressed with polyurethane film (control) were assessed per day (n = 40 wounds). The rate of healing, inflammatory response, restoration of the epithelium and blood vessel and collagen formation were evaluated. No difference was found in the rate of healing between wounds treated with Acticoat™ and the control wounds. Inflammation was increased in Acticoat™-treated wounds on day 3 post-wounding compared to the control wounds. However, by day 15 post-wounding, the epithelium of the Acticoat™-treated wounds closely resembled normal epithelium. Acticoat™-treated wounds also contained a higher proportion of mature blood vessels, and differences in collagen deposition were apparent. Despite inducing an inflammatory response, Acticoat™ did not delay healing in acute wounds. Conversely, the improved quality of the epithelium and blood vessels within Acticoat™-treated wounds indicates that Acticoat™ has a beneficial effect on healing.

Salivary proteomics in bisphosphonate-related osteonecrosis of the jaw

OBJECTIVE

The objective of this study was to identify differentially expressed salivary proteins in bisphosphonate-related osteonecrosis of the jaw (BRONJ) patients that could serve as biomarkers for BRONJ diagnosis.

SUBJECTS AND METHODS

Whole saliva obtained from 20 BRONJ patients and 20 controls were pooled within groups. The samples were analyzed using iTRAQ-labeled two-dimensional liquid chromatography-tandem mass spectrometry.

RESULTS

Overall, 1340 proteins were identified. Of these, biomarker candidates were selected based on P-value (<0.001), changes in protein expression (≥1.5-fold increase or decrease), and unique peptides identified (≥2). Three comparisons made between BRONJ and control patients identified 200 proteins to be differentially expressed in BRONJ patients. A majority of these proteins were predicted to have a role in drug metabolism and immunological and dermatological diseases. Of all the differentially expressed proteins, we selected metalloproteinase-9 and desmoplakin for further validation. Immunoassays confirmed increased expression of metalloproteinase-9 in individual saliva (P = 0.048) and serum samples (P = 0.05) of BRONJ patients. Desmoplakin was undetectable in saliva. However, desmoplakin levels tended to be lower in BRONJ serum than controls (P = 0.157).

CONCLUSIONS

Multiple pathological reactions are involved in BRONJ development. One or more proteins identified by this study may prove to be useful biomarkers for BRONJ diagnosis. The role of metalloproteinase-9 and desmoplakin in BRONJ requires further investigation.

Bioengineered matrices--part 2: focal adhesion, integrins, and the fibroblast effect

Initial efforts at biologic skin replacement strategies were mainly directed toward keratinocyte regeneration and epithelial replacement. It soon became evident that without a good dermal scaffold, the long-term efficacy of epithelial replacement was very limited. Further studies have focused on matrix replacement predominantly involving collagen frameworks with or without cellular additions. The fibroblast is central to the process of dermal regeneration and to the success of biologic matrix design. The sequence of cellular focal adhesion, integrin phosphorylated activation, intracellular and extracellular signaling, cytoskeletal activation, changes in cell morphology, and cytokine growth factor interaction are all important in influencing cell proliferation, cell spreading, neocollagenesis, and collagen translocation. A basic acellular matrix with chemical composition and correct physical structure (pore size and resistance) that takes cognizance of this sequence of matrix deposition and fibroblast functionality should be successful in promoting intrinsic healing and dermal replacement.

Chronic wound fluid--thinking outside the box

Chronic wounds are associated with an altered wound milieu that results from an imbalance in extracellular matrix (ECM) homeostasis. This alteration is characterized by an increased destruction and degradation of components of the ECM with a concomitant lack of synthesis of these elements. Traditionally wound fluid has been considered a reflection of the internal wound milieu. It has been used to monitor and reflect on the chronic status of a wound or to measure the efficacy of wound treatment. However, on closer inspection of chronic wound fluid, certain components of the fluid, particularly matrix metalloproteinases (MMPs) and their subcomponents (MMP-9) have been found to exist at higher levels in wound fluid than in the corresponding wound. There is mounting evidence that much of the destructive effects observed in chronic wounds may be compounded by components of the wound exudate which are corrosive in nature resulting in a continuum of ECM breakdown. Isolation of these components has identified MMPs, in particular MMP-9 as dominant in this destructive process. Additionally an association has been made between high bacterial levels and elevated MMP9 in chronic wounds. Agents that have efficacy against MMP-9 and significant antibacterial potency thus provide a dual defense against chronic wounds. It is likely that these agents cause a change in the chronic wound fluid components that more closely resemble the balance of proteases and growth factors seen acute wounds, thus triggering a positive wound healing process. Nanocrystalline silver appears to fulfill these criteria. A strategy is suggested whereby wound fluid is directly targeted to diminish the corrosive wound fluid elements in an attempt to break the ongoing destructive inflammatory cycle. This presents a relatively new treatment paradigm attempting to influence wound healing by working from without to initiate changes within.