Design and characterization of a chitosan physical gel promoting wound healing in mice

Chitosan and chitosan/turmeric-based membranes for wound healing: Production, characterization and application

In the present study, chitosan and chitosan/turmeric-based membranes were produced, characterized and applied in in vivo experiments showing the applicability for skin wound repair. Chitosan 1 % (w/v), chitosan + glycerol 30 % (w/w) and chitosan + glycerol 30 % + turmeric 1.5 % (w/w) membranes were produced through the casting technique. Self-sustainable, homogeneous, and flexible membranes were obtained from all materials tested. The FTIR spectra showed the main vibrational bands for materials used in the chemical groups. The membranes containing glycerol are more flexible than those formed with pure chitosan. Membranes formed with glycerol and glycerol/turmeric are more hydrophilic compared to the membranes formed by pure chitosan. The in vivo results showed that the group who received the chi/gly/turmeric membrane had a statistically greater reduction in the injured area, as well as a better healing process in the histological analysis compared to the other experimental groups. The material developed here is from a natural source, low cost and easy to apply and can accelerate the process of repairing skin lesions.

Chitosan-poloxamer-based thermosensitive hydrogels containing zinc gluconate/recombinant human epidermal growth factor benefit for antibacterial and wound healing

Chitosan/poloxamer-based thermosensitive hydrogels containing zinc gluconate/recombinant human epidermal growth factor (ZnG/rhEGF@Chit/Polo) were developed as a convenient, safe and effective dressing for skin wound treatment. Their fabrication procedure and characterization were reported, and their morphology was examined by a scanning electron microscope. Antibacterial and biofilms activities were evaluated by in vitro tests to reveal the inhibitory effects and scavenging activity on the biofilms of Staphylococcus aureus and Pseudomonas aeruginosa. ZnG/rhEGF@Chit/Polo was also investigated as a potential therapeutic agent for wound healing therapy. In vivo wound healing studies on rats for 21 days proves that ZnG/rhEGF@Chit/Polo supplements the requisite Zn²⁺ and rhEGF for wound healing to promote the vascular remodeling and collagen deposition, facilitate fibrogenesis, and reduce the level of interleukin 6 for wound basement repair, and thus is a good wound therapy.

Biocompatibility of the Biopolymer Cyanoflan for Applications in Skin Wound Healing

There is a great demand for the development of novel wound dressings to overcome the time and costs of wound care performed by a vast number of clinicians, especially in the current overburdened healthcare systems. In this study, Cyanoflan, a biopolymer secreted by a marine unicellular cyanobacterium, was evaluated as a potential biomaterial for wound healing. Cyanoflan effects on cell viability, apoptosis, and migration were assessed in vitro, while the effect on tissue regeneration and biosafety was evaluated in healthy Wistar rats. The cell viability and apoptosis of fibroblasts and endothelial cells was not influenced by the treatment with different concentrations of Cyanoflan, as observed by flow cytometry. Moreover, the presence of Cyanoflan did not affect cell motility and migratory capacity, nor did it induce reactive oxygen species production, even revealing an antioxidant behavior regarding the endothelial cells. Furthermore, the skin wound healing in vivo assay demonstrated that Cyanoflan perfectly adapted to the wound bed without inducing systemic or local oxidative or inflammatory reaction. Altogether, these results suggest that Cyanoflan is a promising biopolymer for the development of innovative applications to overcome the many challenges that still exist in skin wound healing.

Design and evaluation of a multifunctional thermosensitive poloxamer-chitosan-hyaluronic acid gel for the treatment of skin burns

The main goal of this study was the design, development and characterization of a poloxamer/chitosan/hyaluronic based vehicle including three biological antioxidant molecules such as vitamins A, D and E aimed at improving the treatment of skin burns. The physical characterization of hydrogel, its mechanical and rheological properties as well as internal structure were investigated. Furthermore, biological characteristics such as ex vivo antimicrobial properties and in vivo wound healing were also accomplished and compared with a commercial reference. Results showed optimal physicochemical properties with biocompatible pH value of 4.6 ± 0.1 and zeta potential dependent on pH. The swelling rate was around 350% with optimal wettability, adhesion and leakage properties, as well as thermosensitive gelation processes. The microbiological assay demonstrated similar antimicrobial activity to that of commercial reference. In vivo tolerance study revealed no skin reactions. Finally, the wound healing efficacy of hydrogel in skin burn model showed dermal appendages and similar epidermis, dermis and stratum corneum to the commercial reference. These findings indicated that our hydrogel loading vitamins could be considered an outstanding candidate for further clinical studies.

Crafting Polymeric and Peptidic Hydrogels for Improved Wound Healing

Wound healing is a multifaceted biological process involving the replacement of damaged tissues and cellular structures, restoring the skin barrier's function, and maintaining internal homeostasis. Over the past two decades, numerous approaches are undertaken to improve the quality and healing rate of complex acute and chronic wounds, including synthetic and natural polymeric scaffolds, skin grafts, and supramolecular hydrogels. In this context, this review assesses the advantages and drawbacks of various types of supramolecular hydrogels including both polymeric and peptide-based hydrogels for wound healing applications. The molecular design features of natural and synthetic polymers are examined, as well as therapeutic-based and drug-free peptide hydrogels, and the strategies for each system are analyzed to integrate key elements such as biocompatibility, bioactivity, stimuli-responsiveness, site specificity, biodegradability, and clearance.

Chitosan-Based Polyelectrolyte Complexes for Doxorubicin and Zoledronic Acid Combined Therapy to Overcome Multidrug Resistance

This study aimed to develop nanovectors co-encapsulating doxorubicin (Doxo) and zoledronic acid (Zol) for a combined therapy against Doxo-resistant tumors. Chitosan (CHI)-based polyelectrolyte complexes (PECs) prepared by ionotropic gelation technique were proposed. The influence of some experimental parameters was evaluated in order to optimize the PECs in terms of size and polydispersity index (PI). PEC stability was studied by monitoring size and zeta potential over time. In vitro studies were carried out on wild-type and Doxo-resistant cell lines, to assess both the synergism between Doxo and Zol, as well as the restoring of Doxo sensitivity. Polymer concentration, incubation time, and use of a surfactant were found to be crucial to achieving small size and monodisperse PECs. Doxo and Zol, only when encapsulated in PECs, showed a synergistic antiproliferative effect in all the tested cell lines. Importantly, the incubation of Doxo-resistant cell lines with Doxo/Zol co-encapsulating PECs resulted in the restoration of Doxo sensitivity.

Chitosan Gel to Treat Pressure Ulcers: A Clinical Pilot Study

Chitosan is biopolymer with promising properties in wound healing. Chronic wounds represent a significant burden to both the patient and the medical system. Among chronic wounds, pressure ulcers are one of the most common types of complex wound. The efficacy and the tolerability of chitosan gel formulation, prepared into the hospital pharmacy, in the treatment of pressure ulcers of moderate severity were evaluated. The endpoint of this phase II study was the reduction of the area of the lesion by at least 20% after four weeks of treatment. Thus, 20 adult volunteers with pressure ulcers within predetermined parameters were involved in a 30 days study. Dressing change was performed twice a week at outpatient clinic upon chronic wounds management. In the 90% of patients involved in the study, the treatment was effective, with a reduction of the area of the lesion and wound healing progress. The study demonstrated the efficacy of the gel formulation for treatment of pressure ulcers, also providing a strong reduction of patient management costs.

Autoclavable physically-crosslinked chitosan cryogel as a wound dressing

Moist wounds were known to heal more rapidly than dry wounds. Hydrogel wound dressings were suitable for the moist wound healing because of their hyperhydrous structure. Chitosan was a strong candidate as a base material for hydrogel wound dressings because the polymer had excellent biological properties that promoted wound healing. We previously developed physically-crosslinked chitosan cryogels, which were prepared solely by freeze-thawing of a chitosan-gluconic acid conjugate (CG) aqueous solution, for wound treatment. The CG cryogels were disinfected by immersing in 70% ethanol before applying to wounds in our previous study. In the present study, we examined the influence of autoclave sterilization (121°C, 20 min) on the characteristics of CG cryogel because complete sterilization was one of the fundamental requirements for medical devices. We found that optimum value of gluconic acid content of CG, defined as the number of the incorporated gluconic acid units per 100 glucosamine units of chitosan, was 11 for autoclaving. An increased crosslinking level of CG cryogel on autoclaving enhanced resistance of the gels to enzymatic degradation. Furthermore, the autoclaved CG cryogels retained favorable biological properties of the pre-autoclaved CG cryogels in that they showed the same hemostatic activity and efficacy in repairing full-thickness skin wounds as the pre-autoclaved CG cryogels. These results showed the great potential of autoclavable CG cryogels as a practical wound dressing.

Engineered Biopolymeric Scaffolds for Chronic Wound Healing

Skin regeneration requires the coordinated integration of concomitant biological and molecular events in the extracellular wound environment during overlapping phases of inflammation, proliferation, and matrix remodeling. This process is highly efficient during normal wound healing. However, chronic wounds fail to progress through the ordered and reparative wound healing process and are unable to heal, requiring long-term treatment at high costs. There are many advanced skin substitutes, which mostly comprise bioactive dressings containing mammalian derived matrix components, and/or human cells, in clinical use. However, it is presently hypothesized that no treatment significantly outperforms the others. To address this unmet challenge, recent research has focused on developing innovative acellular biopolymeric scaffolds as more efficacious wound healing therapies. These biomaterial-based skin substitutes are precisely engineered and fine-tuned to recapitulate aspects of the wound healing milieu and target specific events in the wound healing cascade to facilitate complete skin repair with restored function and tissue integrity. This mini-review will provide a brief overview of chronic wound healing and current skin substitute treatment strategies while focusing on recent engineering approaches that regenerate skin using synthetic, biopolymeric scaffolds. We discuss key polymeric scaffold design criteria, including degradation, biocompatibility, and microstructure, and how they translate to inductive microenvironments that stimulate cell infiltration and vascularization to enhance chronic wound healing. As healthcare moves toward precision medicine-based strategies, the potential and therapeutic implications of synthetic, biopolymeric scaffolds as tunable treatment modalities for chronic wounds will be considered.

Stimuli-responsive chitosan/poly (N-isopropylacrylamide) semi-interpenetrating polymer networks: effect of pH and temperature on their rheological and swelling properties

The aim of this work was to synthesize semi-interpenetrating polymer networks (semi-IPNs) by free radical polymerization of N-isopropylacrylamide [poly (NIPAAm)], in the presence of chitosan (CHI), and to study the effect of pH and temperature changes on their rheological and swelling properties. The semi-IPNs are thermally stable up to about 400 °C and the presence of CHI increases the thermal degradation rate compared to bare poly (NIPAAm). The prepared systems presents a well-defined porosity and proved to be non-toxic, in vitro, on human embryonic skin fibroblast, thus offering appropriate support for cell proliferation. The semi-IPNs present, at physiological pH, swelling degrees well below those of the pure poly (NIPAAm). Differently, at acidic pH, the CHI macromolecules are protonated and become much more permeable to the diffusion of water giving a swelling degree that approaches that of bare poly (NIPAAm). The viscoelastic moduli of the semi-IPNs increase as a function of pH while the LCST remain unchanged. Moreover, the semi-IPNs viscoelastic moduli increase with the increase of CHI content and, in particular, the difference between the elastic modulus before and after the sol/gel transition is higher for the semi-IPN than for bare poly (NIPAAm) just at about physiological conditions.

Propionyl-L-Carnitine Enhances Wound Healing and Counteracts Microvascular Endothelial Cell Dysfunction

Background

Impaired wound healing represents a high cost for health care systems. Endothelial dysfunction characterizes dermal microangiopathy and contributes to delayed wound healing and chronic ulcers. Endothelial dysfunction impairs cutaneous microvascular blood flow by inducing an imbalance between vasorelaxation and vasoconstriction as a consequence of reduced nitric oxide (NO) production and the increase of oxidative stress and inflammation. Propionyl-L-carnitine (PLC) is a natural derivative of carnitine that has been reported to ameliorate post-ischemic blood flow recovery.

Methods and Results

We investigated the effects of PLC in rat skin flap and cutaneous wound healing. A daily oral PLC treatment improved skin flap viability and associated with reactive oxygen species (ROS) reduction, inducible nitric oxide synthase (iNOS) and NO up-regulation, accelerated wound healing and increased capillary density, likely favoring dermal angiogenesis by up-regulation for iNOS, vascular endothelial growth factor (VEGF), placental growth factor (PlGF) and reduction of NADPH-oxidase 4 (Nox4) expression. In serum-deprived human dermal microvascular endothelial cell cultures, PLC ameliorated endothelial dysfunction by increasing iNOS, PlGF, VEGF receptors 1 and 2 expression and NO level. In addition, PLC counteracted serum deprivation-induced impairment of mitochondrial β-oxidation, Nox4 and cellular adhesion molecule (CAM) expression, ROS generation and leukocyte adhesion. Moreover, dermal microvascular endothelial cell dysfunction was prevented by Nox4 inhibition. Interestingly, inhibition of β-oxidation counteracted the beneficial effects of PLC on oxidative stress and endothelial dysfunction.

Conclusion

PLC treatment improved rat skin flap viability, accelerated wound healing and dermal angiogenesis. The beneficial effects of PLC likely derived from improvement of mitochondrial β-oxidation and reduction of Nox4-mediated oxidative stress and endothelial dysfunction. Antioxidant therapy and pharmacological targeting of endothelial dysfunction may represent a promising tool for the treatment of delayed wound healing or chronic ulcers.

Nanoparticle-Integrated Hydrogels as Multifunctional Composite Materials for Biomedical Applications

This review focuses on the most recent developments in the field of nanocomposite hydrogels intended for biomedical applications. Nanocomposite hydrogels are hydrated polymeric networks with a physically or covalently crosslinked three-dimensional (3D) structure swollen with water, in the presence of nanoparticles or nanostructures. A wide array of nanomaterials (polymeric, carbon-based, metallic, ceramic) can be incorporated within the hydrogel network to obtain reinforced nanocomposite hydrogels. Nanocomposites represent a new class of materials with properties absent in the individual components. In particular, the incorporation of nanomaterials within a polymeric hydrogel network is an attractive approach to tailor the mechanical properties of the hydrogels and/or to provide the nanocomposite with responsiveness to external stimuli.

The Use of Biologic Scaffolds in the Treatment of Chronic Nonhealing Wounds

Significance: Injuries to the skin as a result of illness or injury, particularly chronic nonhealing wounds, present a major healthcare problem. Traditional wound care approaches attempt to control the underlying causes, such as infection and ischemia, while the application of wound dressings aims to modify a poorly healing wound environment into a microenvironment more closely resembling an acute wound allowing the body to heal the wound naturally. Recent Advances: Regenerative medicine approaches, such as the use of biologic scaffold materials comprising an intact extracellular matrix (ECM) or individual components of the ECM, are providing new therapeutic options that focus upon the provision of biochemical cues that alter the wound microenvironment to facilitate rapid restoration of normal skin architecture. Critical Issues: The incidence of chronic nonhealing wounds continues to increase. For example, between 15% and 20% of diabetics are likely to develop chronic, nonhealing foot wounds creating an increasing burden on healthcare systems worldwide. Future Directions: Developing a thorough understanding of wound microenvironment and the mechanisms by which biologic scaffolds work in vivo has the potential to markedly improve outcomes in the clinical translation for the treatment of chronic wounds.

Chitin, chitosan, and its derivatives for wound healing: old and new materials

Chitin (β-(1-4)-poly-N-acetyl-d-glucosamine) is widely distributed in nature and is the second most abundant polysaccharide after cellulose. It is often converted to its more deacetylated derivative, chitosan. Previously, many reports have indicated the accelerating effects of chitin, chitosan, and its derivatives on wound healing. More recently, chemically modified or nano-fibrous chitin and chitosan have been developed, and their effects on wound healing have been evaluated. In this review, the studies on the wound-healing effects of chitin, chitosan, and its derivatives are summarized. Moreover, the development of adhesive-based chitin and chitosan are also described. The evidence indicates that chitin, chitosan, and its derivatives are beneficial for the wound healing process. More recently, it is also indicate that some nano-based materials from chitin and chitosan are beneficial than chitin and chitosan for wound healing. Clinical applications of nano-based chitin and chitosan are also expected.