Rapid hemostatic and mild polyurethane-urea foam wound dressing for promoting wound healing

Tissue-engineered PLLA/gelatine nanofibrous scaffold promoting the phenotypic expression of epithelial and smooth muscle cells for urethral reconstruction

The repair and regeneration of tissues using tissue-engineered scaffolds represent the ultimate goal of regenerative medicine. Despite rapid developments in the field, urethral tissue engineering methods are still insufficient to replicate natural urethral tissue because the bioactivity of existing scaffolds is inefficient, especially for large tissue defects, which require large tissue-engineered scaffolds. Here, we describe the efficiency of gelatine-functionalized, tubular nanofibrous scaffolds of poly(l-lactic acid) (PLLA) in regulating the phenotypic expression of epithelial cells (ECs) and smooth muscle cells (SMCs) for urethral reconstruction. Flexible PLLA/gelatine tubular nanofibrous scaffolds with hierarchical architecture were fabricated by electrospinning. The PLLA/gelatine nanofibrous scaffold exhibited enhanced hydrophilicity and significantly promoted the adhesion, oriented elongation, and proliferation of New Zealand rabbit autologous ECs and SMCs simultaneously. Compared with pure PLLA nanofibrous scaffold, PLLA/gelatine nanofibrous scaffolds upregulated the expression of keratin (AE1/AE3) in ECs and actin (α-SMA) in SMCs as well as the synthesis of elastin. Three months of in vivo scaffold replacement of New Zealand rabbit urethras indicated that a tubular cellularized PLLA/gelatine nanofibrous scaffold maintained urethral patency and facilitated oriented SMC remodeling, lumen epithelialization, and angiogenesis. Our observations showed the synergistic effects of nano-morphology and biochemical clues in the design of biomimetic scaffolds, which can effectively promote urethral regeneration.

Self-Healing Hydrogels: The Next Paradigm Shift in Tissue Engineering?

Given their durability and long-term stability, self-healable hydrogels have, in the past few years, emerged as promising replacements for the many brittle hydrogels currently being used in preclinical or clinical trials. To this end, the incompatibility between hydrogel toughness and rapid self-healing remains unaddressed, and therefore most of the self-healable hydrogels still face serious challenges within the dynamic and mechanically demanding environment of human organs/tissues. Furthermore, depending on the target tissue, the self-healing hydrogels must comply with a wide range of properties including electrical, biological, and mechanical. Notably, the incorporation of nanomaterials into double-network hydrogels is showing great promise as a feasible way to generate self-healable hydrogels with the above-mentioned attributes. Here, the recent progress in the development of multifunctional and self-healable hydrogels for various tissue engineering applications is discussed in detail. Their potential applications within the rapidly expanding areas of bioelectronic hydrogels, cyborganics, and soft robotics are further highlighted.

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.

Nanocomposite foams based on flexible biobased thermoplastic polyurethane and ZnO nanoparticles as potential wound dressing materials

In the present study biobased and soft thermoplastic polyurethane (TPU), obtained by polymerization from fatty acids, was used to produce TPU/ZnO nanocomposite foams by thermally induced phase separation method (TIPS). The produced foams were characterized and evaluated regarding their potential uses as wound dressing materials. The structure and morphology of the prepared flexible polymer foams with different content of ZnO nanofiller (1, 2, 5 and 10 wt% related to the polymer) were studied by Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). Highly porous nanocomposite structure made of interconnected pores with dimensions between 10 and 60 μm was created allowing water vapor transmission rate (WVTR) up to 8.9 mg/cm²·h. The TPU/ZnO foams, tested for their ability to support cells and their growth, showed highest cell proliferation for TPU nanocomposite foams with 2 and 5 wt% ZnO. Overall, the nanocomposite foams displayed a low cytotoxic potential (varied proportionally to the ZnO content) and good biocompatibility. All tested nanocomposite foams were found to be significantly active against biofilms formed by different Gram-positive (Enterococcus faecalis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Based on their behaviors, flexible TPU/ZnO nanocomposite foams can be considered for biomedical applications such as potential active wound dressing.

Efficiency of Multiparticulate Delivery Systems Loaded with Flufenamic Acid Designed for Burn Wound Healing Applications

Burns are soft tissue injuries that require particular care for wound healing. Current tissue engineering approaches are aimed at identifying the most efficient treatment combinations to restore the tissue properties and function by using adapted scaffolds or delivery platforms for tissue repair and regeneration by triggering molecules. To reduce the inflammation associated with skin burns, the addition of an anti-inflammatory factor in these scaffolds would greatly increase the quality of the therapy. Therefore, this study is aimed at obtaining and validating a novel multiparticulate system based on a collagen matrix with controlled delivery of flufenamic acid anti-inflammatory drug for burn wound healing applications. In this work, we have characterized the properties and biocompatibility of these multiparticulate drug delivery systems (MDDS) and we have demonstrated their efficiency against burns and soft tissue lesions, particularly when the drug was microencapsulated, and thus with a controlled release. This study contributes to the advancement in therapy of burns and burn wound healing applications.

Preparation of hydroxylated lecithin complexed iodine/carboxymethyl chitosan/sodium alginate composite membrane by microwave drying and its applications in infected burn wound treatment

Improving the antibacterial properties of membrane wound dressings of natural polymers is crucial. Iodine is an important safe inorganic antibacterial agent, but was confined in the composition with polymer membranes due to the challenges of homogeneity and stability during drying. In the present work, iodine was complexed with hydroxylated lecithin (HL) to improve its stability and complexing efficiency for the composition with carboxymethly chitosan/sodium alginate. With the aid of microwave drying, hydroxylated lecithin complexed iodine/carboxymethly chitosan/sodium alginate (HLI/CMCS/SA) composite membranes with homogeneously distributions of HLI, high contents of activated iodine, good mechanical and swelling properties, proper water vapor permeability, pH controllable iodine release and excellent antibacterial properties were prepared. The composite membranes exhibited high repairing efficiencies for the infection of a rat model of the seawater immersed wound infection of deep partial-thickness burns. This novel antibacterial composite membrane can be potentially used as a high performance wound dressing for treating and repairing open trauma infections.

HRP-mediated graft polymerization of acrylic acid onto silk fibroins and in situ biomimetic mineralization

Silk fibroin (SF) can be extensively utilized in biomedical areas owing to its appreciable bioactivity. In this study, biocompatible composites of SF and hydroxyapatite (HAp) were fabricated through in situ biomimetic mineralization process. Graft copolymerization of acrylic acid (AA) onto SF was conducted by using the catalytic system of acetylacetone (ACAC), hydrogen peroxide (H₂O₂) and horseradish peroxidase (HRP), for enhancing the deposition of apatite onto the fibroin chains. Subsequently, biomimetic mineralization of the prepared fibroin-based membrane was performed in Ca/P solutions to synthesize the organized SF/HAp composites. The efficacies of graft copolymerization and biomimetic mineralization were evaluated by means of ATR-FTIR, GPC, EDS-Mapping, XRD and others. The results denoted that AA was successfully graft-copolymerized with fibroin and formed the copolymer of silk fibroin-graft-polyacrylic acid (SF-g-PAA), and the grafting percentage (GP) and grafting efficiency (GE) under the optimal condition reached to 23.2% and 29.4%, respectively. More mineral phases were detected on the surface of SF-g-PAA membrane after mineralization process when compared to that of the untreated fibroin membrane, companying with an improved mechanical property. According to MG-63 cell viability and fluorescent adhesion assays, the mineralized SF-g-PAA composite showed satisfactory biocompatibility and exceptional adhesive effects as well. The synthetized composite of SF-g-PAA/HAp can be potentially applied in the fields of bone tissue engineering.

Hyaluronic Acid and Polyethylene Glycol Hybrid Hydrogel Encapsulating Nanogel with Hemostasis and Sustainable Antibacterial Property for Wound Healing

Immediate hemorrhage control and anti-infection play important roles in the wound management. Besides, a moist environment is also beneficial for wound healing. Hydrogels are promising materials in urgent hemostasis and drug release. However, hydrogels have the disadvantage of rapid release profiles, leading to the exposure to high drug concentrations. In this study, we constructed hybrid hydrogels with rapid hemostasis and sustainable antibacterial property combining aminoethyl methacrylate hyaluronic acid (HA-AEMA) and methacrylated methoxy polyethylene glycol (mPEG-MA) hybrid hydrogels and chlorhexidine diacetate (CHX)-loaded nanogels. The CHX-loaded nanogels (CLNs) were prepared by the enzyme degradation of CHX-loaded lysine-based hydrogels. The HA-AEMA and mPEG-MA hybrid hydrogel loaded with CLNs (labeled as Gel@CLN) displayed a three-dimensional microporous structure and exhibited excellent swelling, mechanical property, and low cytotoxicity. The Gel@CLN hydrogel showed a prolonged release period of CHX over 240 h and the antibacterial property over 10 days. The hemostasis and wound-healing properties were evaluated in vivo using a mouse model. The results showed that hydrogel had the rapid hemostasis capacity and accelerated wound healing. In summary, CLN-loaded hydrogels may be excellent candidates as hemostasis and anti-infection materials for the wound dressing application.

Polycaprolactone nanofibers functionalized with placental derived extracellular matrix for stimulating wound healing activity

Impaired wound healing is primarily associated with inadequate angiogenesis, repressed cell migration, deficient synthesis of extracellular matrix (ECM) component/growth factors, and altered inflammatory responses in the wound bed environment.

Can regenerative medicine and nanotechnology combine to heal wounds? The search for the ideal wound dressing

Skin is the outermost covering of the human body and at the same time the largest organ comprising 15% of body weight and 2 m2 surface area. Skin plays a key role as a barrier against the outer environment depending on its thickness, color and structure, which differ from one site to another. The four major types of problematic wounds include ulcers (diabetic, venous, pressure) and burn wounds. Developing novel dressings helps us to improve the wound healing process in difficult patients. Recent advances in regenerative medicine and nanotechnology are revolutionizing the field of wound healing. Antimicrobial activity, exogenous cell therapy, growth factor delivery, biodegradable and biocompatible matrix construction, all play a role in hi-tech dressing design. In the present review, we discuss how the principles of regenerative medicine and nanotechnology can be combined in innovative wound dressings.

Development, Optimization and In Vitro/In Vivo Characterization of Collagen-Dextran Spongious Wound Dressings Loaded with Flufenamic Acid

The aim of this study was the development and optimization of some topical collagen-dextran sponges with flufenamic acid, designed to be potential dressings for burn wounds healing. The sponges were obtained by lyophilization of hydrogels based on type I fibrillar collagen gel extracted from calf hide, dextran and flufenamic acid, crosslinked and un-crosslinked, and designed according to a 3-factor, 3-level Box-Behnken experimental design. The sponges showed good fluid uptake ability quantified by a high swelling ratio. The flufenamic acid release profiles from sponges presented two stages—burst effect resulting in a rapid inflammation reduction, and gradual delivery ensuring the anti-inflammatory effect over a longer burn healing period. The resistance to enzymatic degradation was monitored through a weight loss parameter. The optimization of the sponge formulations was performed based on an experimental design technique combined with response surface methodology, followed by the Taguchi approach to select those formulations that are the least affected by the noise factors. The treatment of experimentally induced burns on animals with selected sponges accelerated the wound healing process and promoted a faster regeneration of the affected epithelial tissues compared to the control group. The results generated by the complex sponge characterization indicate that these formulations could be successfully used for burn dressing applications.

Hemostatic kaolin-polyurethane foam composites for multifunctional wound dressing applications

There are numerous challenges associated with the acute care of traumatic limb injuries in forward military settings. A lack of immediate medical facilities necessitates that the wound dressing perform multiple tasks including exudate control, infection prevention, and physical protection of the wound for extended periods of time. Here, kaolin was incorporated into recently developed robust polyurethane (PU) hydrogel foams at 1-10wt% in an effort to impart hemostatic character. ATR-IR and gel fraction analysis demonstrated that the facile, one-pot synthesis of the PU hydrogel was unaffected by kaolin loading, as well as the use of a non-toxic catalyst, which significantly improved cytocompatibility of the materials. Kaolin was generally well dispersed throughout the PU matrix, though higher loadings exhibited minor evidence of aggregation. Kaolin-PU composites exhibited burst release of ciprofloxacin over 2h, the initial release rates of which increased with kaolin loading. Kaolin loading imparted excellent hemostatic character to the PU foams at relatively low loading levels (5wt%). This work demonstrates the simple and inexpensive synthesis of robust, hemostatic, and absorptive kaolin-PU foams that have promising potential as multifunctional wound dressing materials.