A bioengineered drug-Eluting scaffold accelerated cutaneous wound healing In diabetic mice

Enhancing diabetic wound healing: advances in electrospun scaffolds from pathogenesis to therapeutic applications

Diabetic wounds are a significant subset of chronic wounds characterized by elevated levels of inflammatory cytokines, matrix metalloproteinases (MMPs), and reactive oxygen species (ROS). They are also associated with impaired angiogenesis, persistent infection, and a high likelihood of hospitalization, leading to a substantial economic burden for patients. In severe cases, amputation or even mortality may occur. Diabetic foot ulcers (DFUs) are a common complication of diabetes, with up to 25% of diabetic patients being at risk of developing foot ulcers over their lifetime, and more than 70% ultimately requiring amputation. Electrospun scaffolds exhibit a structural similarity to the extracellular matrix (ECM), promoting the adhesion, growth, and migration of fibroblasts, thereby facilitating the formation of new skin tissue at the wound site. The composition and size of electrospun scaffolds can be easily adjusted, enabling controlled drug release through fiber structure modifications. The porous nature of these scaffolds facilitates gas exchange and the absorption of wound exudate. Furthermore, the fiber surface can be readily modified to impart specific functionalities, making electrospinning nanofiber scaffolds highly promising for the treatment of diabetic wounds. This article provides a concise overview of the healing process in normal wounds and the pathological mechanisms underlying diabetic wounds, including complications such as diabetic foot ulcers. It also explores the advantages of electrospinning nanofiber scaffolds in diabetic wound treatment. Additionally, it summarizes findings from various studies on the use of different types of nanofiber scaffolds for diabetic wounds and reviews methods of drug loading onto nanofiber scaffolds. These advancements broaden the horizon for effectively treating diabetic wounds.

Recent Progress in Development of Dressings Used for Diabetic Wounds with Special Emphasis on Scaffolds

Diabetic wound (DW) is a secondary application of uncontrolled diabetes and affects about 42.2% of diabetics. If the disease is left untreated/uncontrolled, then it may further lead to amputation of organs. In recent years, huge research has been done in the area of wound dressing to have a better maintenance of DW. These include gauze, films, foams or, hydrocolloid-based dressings as well as polysaccharide- and polymer-based dressings. In recent years, scaffolds have played major role as biomaterial for wound dressing due to its tissue regeneration properties as well as fluid absorption capacity. These are three-dimensional polymeric structures formed from polymers that help in tissue rejuvenation. These offer a large surface area to volume ratio to allow cell adhesion and exudate absorbing capacity and antibacterial properties. They also offer a better retention as well as sustained release of drugs that are directly impregnated to the scaffolds or the ones that are loaded in nanocarriers that are impregnated onto scaffolds. The present review comprehensively describes the pathogenesis of DW, various dressings that are used so far for DW, the limitation of currently used wound dressings, role of scaffolds in topical delivery of drugs, materials used for scaffold fabrication, and application of various polymer-based scaffolds for treating DW.

Application of Electrospun Nanofiber Membrane in the Treatment of Diabetic Wounds

Diabetic wounds are complications of diabetes which are caused by skin dystrophy because of local ischemia and hypoxia. Diabetes causes wounds in a pathological state of inflammation, resulting in delayed wound healing. The structure of electrospun nanofibers is similar to that of the extracellular matrix (ECM), which is conducive to the attachment, growth, and migration of fibroblasts, thus favoring the formation of new skin tissue at the wound. The composition and size of electrospun nanofiber membranes can be easily adjusted, and the controlled release of loaded drugs can be realized by regulating the fiber structure. The porous structure of the fiber membrane is beneficial to gas exchange and exudate absorption at the wound, and the fiber surface can be easily modified to give it function. Electrospun fibers can be used as wound dressing and have great application potential in the treatment of diabetic wounds. In this study, the applications of polymer electrospun fibers, nanoparticle-loaded electrospun fibers, drug-loaded electrospun fibers, and cell-loaded electrospun fibers, in the treatment of diabetic wounds were reviewed, and provide new ideas for the effective treatment of diabetic wounds.

Acellular Scaffolds as Innovative Biomaterial Platforms for the Management of Diabetic Wounds

Diabetic wound (DW) is one of the leading complications of patients having a long history of uncontrolled diabetes. Moreover, it also imposes an economic burden on people suffering from wounds to manage the treatment. The major impending factors in the treatment of DW are infection, prolonged inflammation and decreased oxygen levels. Since these non-healing wounds are associated with an extended recovery period, the existing therapies provide treatment for a limited period only. The areas covered in this review are general sequential events of wound healing along with DW's pathophysiology, the origin of DW and success, as well as limitations of existing therapies. This systematic review's significant aspect is to highlight the fabrication, characterization and applications of various acellular scaffolds used to heal DW. In addition to that, cellular scaffolds are also described to a limited extent.

Limited Treatment Options for Diabetic Wounds: Barriers to Clinical Translation Despite Therapeutic Success in Murine Models

Significance: Millions of people worldwide suffer from diabetes mellitus and its complications, including chronic diabetic wounds. To date, there are few widely successful clinical therapies specific to diabetic wounds beyond general wound care, despite the vast number of scientific discoveries in the pathogenesis of defective healing in diabetes. Recent Advances: In recent years, murine animal models of diabetes have enabled the investigation of many possible therapeutics for diabetic wound care. These include specific cell types, growth factors, cytokines, peptides, small molecules, plant extracts, microRNAs, extracellular vesicles, novel wound dressings, mechanical interventions, bioengineered materials, and more. Critical Issues: Despite many research discoveries, few have been translated from their success in murine models to clinical use in humans. This massive gap between bench discovery and bedside application begs the simple and critical question: what is still missing? The complexity and multiplicity of the diabetic wound makes it an immensely challenging therapeutic target, and this lopsided progress highlights the need for new methods to overcome the bench-to-bedside barrier. How can laboratory discoveries in animal models be effectively translated to novel clinical therapies for human patients? Future Directions: As research continues to decipher deficient healing in diabetes, new approaches and considerations are required to ensure that these discoveries can become translational, clinically usable therapies. Clinical progress requires the development of new, more accurate models of the human disease state, multifaceted investigations that address multiple critical components in wound repair, and more innovative research strategies that harness both the existing knowledge and the potential of new advances across disciplines.

Polycaprolactone nanofiber coated with chitosan and Gamma oryzanol functionalized as a novel wound dressing for healing infected wounds

This study was conducted to design and evaluate a wound dressing based on a polycaprolactone (PCL) nanofiber coated with gamma oryzanol (GO) and chitosan (CS) in mice model. All the dressings were prepared by electrospinning method, and their morphology and physical properties were investigated. The mice were divided into five groups and treated with I) PCL-sole (PCL), III) PCL-mupirocin (PCL-M), IV) PCL-GO, IV) PCL-CS, and V) PCL-CS-GO. Wound area, total bacterial count, histopathological parameters, and expressions of IL-1β, TNF-α, IL-10, MMP-9, EGF, and VEGF were assessed. The fibers were randomly distributed in PCL group, but loading CS and GO increased the complexity and placing on the dressings. PCLs loaded with GO and CS showed lower viscosity, surface tension, and fiber diameter and higher conductivity and water contact angle compared to unloaded PCLs (P < 0.05). The treatment with PCLs loaded with mupirocin, CS, and GO significantly reduced wound area and total bacterial count (P < 0.05). Loading PCLs with mupirocin, CS, and GO decreased the expressions of IL-1β, TNF-α, MMP-9, but increased the expressions of IL-10 and VEGF compared to the unloaded PCL group (P < 0.05). The most optimal responses to wound healing and physical parameters belonged to the PCL-CS-GO group.

Moringa oleifera standardised aqueous leaf extract-loaded hydrocolloid film dressing: in vivo dermal safety and wound healing evaluation in STZ/HFD diabetic rat model

Previously, Moringa oleifera leaf (MOL) standardised aqueous extract-loaded films were successfully developed and they showed potential wound healing activity in vitro. The objective of this study was to evaluate in vivo dermal safety as well as wound healing efficacy of these MOL film dressings (containing 0.1, 0.5 and 1% MOL) on diabetic rat model. The acute dermal toxicity was carried out on healthy rats, and signs of toxicity over 14 days were observed. For wound healing studies, excision and abrasion wounds were created out on the STZ/HFD-induced diabetic rat model and the wound healing was studied over 21 days. The wound healing evaluation determined by histology staining, hydroxyproline assay and ELISA assays on wound healing related-growth factors, cytokines and chemokines. MOL film formulations exhibited no signs of dermal toxicities. In excision wound model, 0.5% film significantly enhanced the wound closure by 77.67 ± 7.28% at day 7 compared to control group. While in abrasion wounds, 0.5% MOL films accelerated wound closure significantly at 81 ± 4.5% as compared to the control. The histology findings and hydroxyproline assay revealed that high collagen deposition and complete re-epithelialisation were observed for the wounds treated with 0.5 and 1% MOL films. All MOL film dressings had successfully tested non-toxic via in vivo safety dermal toxicity. It was concluded that the 0.5% MOL extract-loaded film had proven to be the most promising approach to accelerate diabetic wound healing process in both full-thickness excision and partial thickness abrasion wounds on the HFD/STZ-induced diabetic type II model.

Development and Evaluation of Multistructured and Hierarchical Epidermal Growth Factor-Poly ( ε -Caprolactone) Scaffolds

In this paper, we separately fabricated the poly ( ε -caprolactone) (PCL) scaffolds containing epidermal growth factor (EGF) by using our-self fabricated electrospinning machine for tissue regeneration application. Several fundamental properties, including the dimensions, wettability, and EGF release profiles, of the fabricated EGF-PCL bead, fibrous, and multistructured scaffolds were characterized by using the scanning electron microscopy (SEM), contact angle goniometer, and vertical diffusion system. The EGF release profiles of three scaffolds were measured for 200 h, and the multistructured scaffold performed stable and long EGF release properties. Furthermore, the in vitro and in vivo experiments were conducted to evaluate the performance of three types of EGF-PCL scaffolds. The NIH-3T3 fibroblast cells were cultured on the scaffolds to study the effects of the released EGF by using the Alamar Blue Cell Viability Assays, fluorescence image analysis, and SEM. The animal experiment demonstrated that the multistructured EGF-PCL scaffold achieved 95% of the wound healing rate to the cut-damaged wounds after 16 days. Moreover, the histopathological skin tissue showed that the wound regenerated well after the treatment of the multistructured EGF-PCL scaffold. The developed multistructured EGF-PCL scaffold has a high potential for the wound healing applications.

Antioxidant Preconditioning Improves the Paracrine Responsiveness of Mouse Bone Marrow Mesenchymal Stem Cells to Diabetic Wound Fluid

Mesenchymal stem cells (MSCs) are a promising therapeutic tool for the treatment of nonhealing diabetic wounds. The pathological nature of the niche microenvironment limits the use of autologous cell therapy in diabetic patients. Prolonged exposure of endogenous MSCs to a pathological microenvironment in vivo reduces their ability to respond to environmental cues. This study investigated the effectiveness of ex vivo antioxidant treatment [N-acetylcysteine (7.5 mM NAC) and Ascorbic acid 2-phosphate (0.6 mM AAP)] to restore the paracrine function of diabetic MSCs. Healthy control [bone marrow stem cells derived from wild-type mice (SC^WT)] (source: wild-type C57BL/6J mice) (n = 12) and impaired/dysfunctional [bone marrow stem cells derived from ob/ob mice (SC^ob)] (source: obese diabetic, B6.Cg-Lep^ob/J mice) (n = 12) MSCs were isolated. Ex vivo treatment groups (SC^WT vs. SC^ob) were as follows: (1) no treatment (baseline phenotype), (2) stimulated with diabetic wound fluid (DWF) (baseline response), (3) antioxidant preconditioning (preconditioned phenotype), and (4) antioxidant preconditioned with subsequent stimulation with DWF (preconditioned response). The paracrine responsiveness on both the molecular (mRNA expression of 80 cytokines and receptors, quantitative polymerase chain reaction microarray) and protein (23-plex bead-array Luminex assay) level was assessed. At baseline, 31 genes were overexpressed (> × 2-fold) and 39 genes were underexpressed (> × 2-fold) in SC^ob versus SC^WT. In conditioned media, significant differences (P < 0.05) were detected at baseline for two proinflammatory cytokines [tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ)], four chemokines [keratinocyte chemoattractant (KC), granulocyte colony-stimulating factor (GCSF), Eotaxin, and macrophage chemoattractant protein (MCP1)], and one anti-inflammatory cytokine [interleukin 10 (IL10)]. Following stimulation with DWF, significant differences (P < 0.05) were detected in the secretion of two chemokines [granulocyte macrophage colony-stimulating factor (GMCSF) and Eotaxin], three proinflammatory cytokines (TNFα, IFNγ, and IL9), and four anti-inflammatory cytokines (IL10, IL4, IL13, and IL3). Antioxidant preconditioning significantly dampened the excessive TNFα response observed in SC^ob and improved the secretion of IL10. Taken together these data suggest that the combined ex vivo treatment of autologous stem cells with NAC and AAP could potentially be an effective strategy to restore the paracrine function of impaired diabetic MSCs before transplantation.

Electrospun Poly(ε-caprolactone) Nanofibrous Mesh for Imiquimod Delivery in Melanoma Therapy

Drug delivery systems (DDS) are commonly employed to administer drug-loaded composites to their therapeutic targets both in vitro and in vivo. Thus, we herein report the study of imiquimod-poly(ε-caprolactone) (IMQ-PCL) nanofibrous meshes for application in melanoma therapy. The preparation route employed was based on the electrospinning technique, with the melanoma cells being cultured on electrospun nanofibrous meshes to study their biocompatibility. All parameters employed, including the flow rate and polymer solution concentration, were examined to gain an improved understanding of the factors influencing the diameter and morphology of the electrospun fibre. The optimised parameters were employed to produce 12 IMQ-PCL nanofibrous meshes with diameters ranging from 100 to 900 nm to the melanoma cell viability. The relationship between the fibrous diameter and the imiquimod release profile was also determined using UV-Vis spectroscopy. In addition, similar results were obtained for the simulated imiquimod release profile obtained by COMSOL Multiphysics®. The IMQ-PCL nanofibrous meshes were found to decrease cell viability by ≥50%, with the number of cells dropping by ~10% over 48 h. As the cell viability was affected by the release of imiquimod, we believe that IMQ-PCL nanofibrous meshes are a promising drug delivery system for application in melanoma therapy.

Graphene-Functionalized Biomimetic Scaffolds for Tissue Regeneration

Graphene is a two-dimensional atomic layer of graphite, where carbon atoms are assembled in a honeycombed lattice structure. Recently, graphene family nanomaterials, including pristine graphene, graphene oxide and reduced graphene oxide, have increasingly attracted a great deal of interest from researchers in a variety of science, engineering and industrial fields because of their unique structural and functional features. In particular, extensive studies have been actively conducted in the biomedical and related fields, including multidisciplinary and emerging areas, as their stimulating effects on cell behaviors have been becoming an increasing concern. Herein, we are attempting to summarize some of recent findings in the fields of tissue regeneration concerning the graphene family nanomaterial-functionalized biomimetic scaffolds, and to provide the promising perspectives for the possible applications of graphene family nanomaterial.

Development and Characterisation of the Imiquimod Poly(2-(2-methoxyethoxy)ethyl Methacrylate) Hydrogel Dressing for Keloid Therapy

The imiquimod-poly(2-(2-methoxyethoxy)ethyl methacrylate) hydrogel (poly(MEO₂MA) hydrogel) dressing was developed for the keloid therapy application. Four groups of the hydrogels, including the imiquimod-poly(MEO₂MA) hydrogel, crosslinked with 0.2 mol %, 0.4 mol %, 0.6 mol %, and 0.8 mol % of di(ethylene glycol) dimethacrylate cross-linker (DEGDMA), were synthesised and characterised for fabricating the imiquimod-poly(MEO₂MA) hydrogel pad. The lower critical solution temperature (LCST) of the poly(MEO₂MA) hydrogel was measured at approximately 28 °C and was used as a trigger to control the imiquimod loading and release. The loaded amounts of the imiquimod in the poly(MEO₂MA) hydrogel, crosslinked with 0.2 mol % and 0.8 mol % of DEGDMA, were about 27.4 μg and 14.1 μg per 1 mm³ of the hydrogel, respectively. The imiquimod-release profiles of two samples were characterised in a phosphate buffered saline (PBS) solution at 37 °C and the released imiquimod amount were about 45% and 46% of the total loaded imiquimod. The Cell Counting Kit-8 (CCK-8) assay was utilised to analyse the cell viability of keloid fibroblasts cultured on the samples of imiquimod-poly(MEO₂MA) hydrogel, crosslinked with 0.2 mol % and 0.8 mol % of DEGDMA. There was around a 34% decrease of the cell viabilities after 2 days, compared with the pure-poly(MEO₂MA) hydrogel samples. Therefore, the developed imiquimod-poly(MEO₂MA) hydrogel dressing can affect the proliferation of keloid fibroblasts. It should be possible to utilise the hydrogel dressing for the keloid therapy application.

Chitosan-Poly(caprolactone) Nanofibers for Skin Repair

Dermal wounds, both acute and chronic, represent a significant clinical challenge and therefore the development of novel biomaterial-based skin substitutes to promote skin repair is essential. Nanofibers have garnered attention as materials to promote skin regeneration due to the similarities in morphology and dimensionality between nanofibers and native extracellular matrix proteins, which are critical in guiding cutaneous wound healing. Electrospun chitosan-poly(caprolactone) (CPCL) nanofiber scaffolds, which combine the important intrinsic biological properties of chitosan and the mechanical integrity and stability of PCL, were evaluated as skin tissue engineering scaffolds using a mouse cutaneous excisional skin defect model. Gross assessment of wound size and measurement of defect recovery over time as well as histological evaluation of wound healing showed that CPCL nanofiber scaffolds increased wound healing rate and promoted more complete wound closure as compared with Tegaderm, a commercially available occlusive dressing. CPCL nanofiber scaffolds represent a biomimetic approach to skin repair by serving as an immediately available provisional matrix to promote wound closure. These nanofiber scaffolds may have significant potential as a skin substitute or as the basis for more complex skin tissue engineering constructs involving integration with biologics.

Biomaterials and Bioactive Factor Delivery Systems for the Control of Macrophage Activation in Regenerative Medicine

Macrophages play an important role in tissue repair, regeneration, and the ability of biomaterials to mediate these processes. Macrophages are highly plastic cells that exhibit altered behavior in response to changes in the microenvironment. With the growing knowledge of the roles that different macrophage phenotypes play in specific pathologies and/or injuries, researchers are now focusing on designing biomaterials to actively control macrophage behavior and promote healing outcomes. In this review, we highlight a variety of biomaterial strategies for controlling macrophage phenotype in chronic wounds, tissue defects, and inflammatory conditions, although these strategies can be applied to many other applications. In particular, we highlight the different situations in which biomaterials should inhibit or promote M1 or M2 activation, or both, for therapeutic outcomes.

Minimizing Skin Scarring through Biomaterial Design

Wound healing continues to be a major burden to patients, though research in the field has expanded significantly. Due to an aging population and increasing comorbid conditions, the cost of chronic wounds is expected to increase for patients and the U.S. healthcare system alike. With this knowledge, the number of engineered products to facilitate wound healing has also increased dramatically, with some already in clinical use. In this review, the major biomaterials used to facilitate skin wound healing will be examined, with particular attention allocated to the science behind their development. Experimental therapies will also be evaluated.

Recent advances in biomaterials for the treatment of diabetic foot ulcers

Diabetes mellitus is one of the most challenging epidemics facing the world today, with over 300 million patients affected worldwide.

Hyaluronic Acid/PLGA Core/Shell Fiber Matrices Loaded with EGCG Beneficial to Diabetic Wound Healing

During the last few decades, considerable research on diabetic wound healing strategies has been performed, but complete diabetic wound healing remains an unsolved problem, which constitutes an enormous biomedical burden. Herein, hyaluronic acid (HA)/poly(lactic-co-glycolic acid, PLGA) core/shell fiber matrices loaded with epigallocatechin-3-O-gallate (EGCG) (HA/PLGA-E) are fabricated by coaxial electrospinning. HA/PLGA-E core/shell fiber matrices are composed of randomly-oriented sub-micrometer fibers and have a 3D porous network structure. EGCG is uniformly dispersed in the shell and sustainedly released from the matrices in a stepwise manner by controlled diffusion and PLGA degradation over four weeks. EGCG does not adversely affect the thermomechanical properties of HA/PLGA-E matrices. The number of human dermal fibroblasts attached on HA/PLGA-E matrices is appreciably higher than that on HA/PLGA counterparts, while their proliferation is steadily retained on HA/PLGA-E matrices. The wound healing activity of HA/PLGA-E matrices is evaluated in streptozotocin-induced diabetic rats. After two weeks of surgical treatment, the wound areas are significantly reduced by the coverage with HA/PLGA-E matrices resulting from enhanced re-epithelialization/neovascularization and increased collagen deposition, compared with no treatment or HA/PLGA. In conclusion, the HA/PLGA-E matrices can be potentially exploited to craft strategies for the acceleration of diabetic wound healing and skin regeneration.