Development of pro-angiogenic skin substitutes for wound healing

Wounds pose significant challenges to public health, primarily due to the loss of the mechanical integrity and barrier function of the skin and impaired angiogenesis, causing physical morbidities and psychological trauma to affect patients. Reconstructing the vasculature of the wound bed is crucial for promoting wound healing, reducing scar formation and enhancing the quality of life for patients. The development of pro-angiogenic skin substitutes has emerged as a promising strategy to facilitate vascularization and expedite the healing process of burn wounds. This review provides an overview of the various types of skin substitutes employed in wound healing, explicitly emphasising those designed to enhance angiogenesis. Synthetic scaffolds, biological matrices and tissue-engineered constructs incorporating stem cells and primary cells, cell-derived extracellular vesicles (EVs), pro-angiogenic growth factors and peptides, as well as gene therapy-based skin substitutes are thoroughly examined. The review summarises the existing challenges, future directions and potential innovations in pro-angiogenic dressing for skin substitutes. It highlights the need for continued research to develop new technologies and combine multiple strategies and factors, and to overcome obstacles and advance the field, ultimately leading to improved outcomes for wound patients.

Three-Dimensional Printed Cellulose for Wound Dressing Applications

Wounds are skin tissue damage due to trauma. Many factors inhibit the wound healing phase (hemostasis, inflammation, proliferation, and alteration), such as oxygenation, contamination/infection, age, effects of injury, sex hormones, stress, diabetes, obesity, drugs, alcoholism, smoking, nutrition, hemostasis, debridement, and closing time. Cellulose is the most abundant biopolymer in nature which is promising as the main matrix of wound dressings because of its good structure and mechanical stability, moisturizes the area around the wound, absorbs excess exudate, can form elastic gels with the characteristics of bio-responsiveness, biocompatibility, low toxicity, biodegradability, and structural similarity with the extracellular matrix (ECM). The addition of active ingredients as a model drug helps accelerate wound healing through antimicrobial and antioxidant mechanisms. Three-dimensional (3D) bioprinting technology can print cellulose as a bioink to produce wound dressings with complex structures mimicking ECM. The 3D printed cellulose-based wound dressings are a promising application in modern wound care. This article reviews the use of 3D printed cellulose as an ideal wound dressing and their properties, including mechanical properties, permeability aspect, absorption ability, ability to retain and provide moisture, biodegradation, antimicrobial property, and biocompatibility. The applications of 3D printed cellulose in the management of chronic wounds, burns, and painful wounds are also discussed.

Advanced Hydrogels as Wound Dressings

Skin is the largest organ of the human body, protecting it against the external environment. Despite high self-regeneration potential, severe skin defects will not heal spontaneously and need to be covered by skin substitutes. Tremendous progress has been made in the field of skin tissue engineering, in recent years, to develop new skin substitutes. Among them, hydrogels are one of the candidates with most potential to mimic the native skin microenvironment, due to their porous and hydrated molecular structure. They can be applied as a permanent or temporary dressing for different wounds to support the regeneration and healing of the injured epidermis, dermis, or both. Based on the material used for their fabrication, hydrogels can be subdivided into two main groups—natural and synthetic. Moreover, hydrogels can be reinforced by incorporating nanoparticles to obtain “in situ” hybrid hydrogels, showing superior properties and tailored functionality. In addition, different sensors can be embedded in hydrogel wound dressings to provide real-time information about the wound environment. This review focuses on the most recent developments in the field of hydrogel-based skin substitutes for skin replacement. In particular, we discuss the synthesis, fabrication, and biomedical application of novel “smart” hydrogels.

Chronic wounds: the challenges of appropriate management

The immense burden imposed by chronic wounds-those persisting over 6 weeks despite active intervention-on patients and health services is well recognised. There are various reasons for why a wound fails to progress towards closure, and clinicians must investigate the underlying cause of wound chronicity, as this information guides the management of such wounds. The TIME framework (T=tissue; I=infection/inflammation; M=moisture balance; E=wound edges) is a useful tool for practitioners to systematically undertake wound assessment and product selection. This article discusses chronic wound management based on the TIME framework, examining the aspects to be considered when managing chronic wounds. It also describes the process of dressing selection for overcoming the various barriers to wound healing, specifically discussing the AQUACEL family of dressings.

An in vitro assessment of bacterial transfer by products used in debridement

OBJECTIVE

The aim of this in vitro study was to investigate the transfer of viable Pseudomonas aeruginosa biofilm microorganisms following treatment with debridement tools.

METHOD

The level of viable biofilm microorganisms transferred by debridement tools was compared following treatment that reflected the clinical practice of each product.

RESULTS

A significant level of microorganism transfer was seen in response to the mechanical debridement tool. Minimal transfer of microorganisms was seen when in vitro-established biofilms were treated with hydroresponsive wound dressing + polyhexamethylene biguanide (HRWD+PHMB, HydroClean plus). Less Pseudomonas aeruginosa was recovered from explants exposed to dressings compared with those exposed to debridement tools suggesting that there was less transfer of bacteria by dressings.

CONCLUSION

The reduced transfer of viable microorganisms by HRWD+PHMB may be the result of significant binding and retention of microbes by the superabsorbent polymer within the dressing, together with enhanced sequestered bacterial killing within the dressing by polymer-bound PHMB. The high levels of microbial transfer/transmission seen for debridement tools suggests that, in the clinical setting, a significant level of bacterial spread over the wound surface and/or surrounding skin by these cleansing tools is likely.

Synthesis and biomedical applications of aerogels: Possibilities and challenges

Aerogels are an exceptional group of nanoporous materials with outstanding physicochemical properties. Due to their unique physical, chemical, and mechanical properties, aerogels are recognized as promising candidates for diverse applications including, thermal insulation, catalysis, environmental cleaning up, chemical sensors, acoustic transducers, energy storage devices, metal casting molds and water repellant coatings. Here, we have provided a comprehensive overview on the synthesis, processing and drying methods of the mostly investigated types of aerogels used in the biological and biomedical contexts, including silica aerogels, silica-polymer composites, polymeric and biopolymer aerogels. In addition, the very recent challenges on these aerogels with regard to their applicability in biomedical field as well as for personalized medicine applications are considered and explained in detail.

The thickness of exudate: does it matter?

The majority of chronic wounds are managed in the community by the district nursing team. With increasing constraints on the health-care budget, it can be tempting to manage exudate by focusing solely on the exudate-handling capability of some of the more absorbent dressings available. However, exudate levels and viscosity can change depending on the patient and the wound, with exudate being a marker of potential infection. Ongoing assessment of the wound, the exudate and the patient is pivotal to effective wound management, with timely and appropriate intervention being key. This article discusses this management, with particular focus on dealing with thick exudate.

A prospective, open, multicentre study to evaluate a new gelling fibre dressing containing silver in the management of venous leg ulcers

This study investigated the performance of a new gelling fibre dressing containing silver (DURAFIBER™ Ag; Smith & Nephew, Hull, UK) in moderate to highly exuding venous leg ulcers with one or more clinical signs of infection. Fourteen patients with venous leg ulceration of median ulcer duration 12·5 weeks, recruited from three centres in South Africa, received treatment with the new dressing for a maximum of 8 weeks. Multilayer compression bandaging was used for all patients, at the majority of assessments. The objectives of this study were to assess the clinical acceptability of the dressing in terms of the following characteristics: antimicrobial properties, the progress of the wound towards healing, wear time, exudate management, conformability, patient comfort, pain on application, pain on removal and dressing integrity. The new dressing was rated as clinically acceptable for all characteristics, for all 14 patients (100%). It was easy to apply and remove; in 96·8% of removals, the dressing stayed intact on removal and could be removed in one piece. Fifty per cent of the wounds healed within the 8-week study duration; between baseline and final assessment, the median percentage reduction in wound area was 98·2% and the median percentage reduction in devitalised tissue was 78%. Exudate levels and wound pain were significantly improved at final assessment compared to baseline assessment, and an increase in the number of patients with healthy peri-wound skin between baseline and final assessment was observed. A reduction in bioburden and signs of clinical infection and an improvement in quality of life were observed over the 8-week period. The average wear time was 6·4 days. This study supports the use of new dressing in the management of moderately to highly exuding venous leg ulcers with clinical signs of infection.

In situ forming antibacterial dextran blend hydrogel for wound dressing: SAA technology vs. spray drying

This study focuses on designing microparticulate carriers based on high-mannuronic alginate and amidated pectin blend loaded with gentamicin sulphate able to move rapidly from dry to soft hydrogel. Supercritical assisted atomization was used to produce microparticles in form of dry powder and characteristics were compared with those obtained by spray-drying. Particles with very high encapsulation efficiency (approximately 100%) and small diameter (less than 2 μm) showed good flowability and high fluid uptake enabling wound site filling and limiting bacterial proliferation. Moisture transmission of the in situ formed hydrogel was about 95 g/m(2)h, ideal to avoid wound dehydration or occlusion phenomena. All formulations presented a burst effect, suitable to prevent infection spreading at the beginning of the therapy, followed by prolonged release (4-10 days) related to drug/polymers ratio. Antimicrobial tests showed stronger effect than pure GS over time (up-to 24 days) and the ability to degrade preformed biofilms, essential to properly treat infected wounds.