Electrospun skin dressings for diabetic wound treatment: a systematic review

Abstract

Diabetes mellitus is a metabolic disease characterized by persistent hyperglycemia associated with a lack of insulin production or insulin resistance. In diabetic patients, the capacity for healing is generally decreased, leading to chronic wounds. One of the most common treatments for chronic wounds is skin dressings, which serve as protection from infection, reduce pain levels, and stimulate tissue healing. Furthermore, electrospinning is one of the most effective techniques used for manufacturing skin dressings.

Objective

The purpose of this study was to perform a systematic review of the literature to examine the effects of electrospun skin dressings from different sources in the process of healing skin wounds using in vivo experiments in diabetic rats.

Methods

The search was carried out according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), and the Medical Subject Headings (MeSH) descriptors were defined as "wound dressing," "diabetes," "in vivo," and "electrospun." A total of 14 articles were retrieved from PubMed and Scopus databases.

Results

The results were based mainly on histological analysis and macroscopic evaluation, demonstrating moderate evidence synthesis for all experimental studies, showing a positive effect of electrospun skin dressings for diabetic wound treatment.

Conclusion

This review confirms the significant benefits of using electrospun skin dressings for skin repair and regeneration. All the inks used were demonstrated to be suitable for dressing manufacturing. Moreover, in vivo findings showed full wound closure in most of the studies, with well-organized dermal and epidermal layers.

Nanomaterials-incorporated hydrogels for 3D bioprinting technology

In the field of tissue engineering and regenerative medicine, various hydrogels derived from the extracellular matrix have been utilized for creating engineered tissues and implantable scaffolds. While these hydrogels hold immense promise in the healthcare landscape, conventional bioinks based on ECM hydrogels face several challenges, particularly in terms of lacking the necessary mechanical properties required for 3D bioprinting process. To address these limitations, researchers are actively exploring novel nanomaterial-reinforced ECM hydrogels for both mechanical and functional aspects. In this review, we focused on discussing recent advancements in the fabrication of engineered tissues and monitoring systems using nanobioinks and nanomaterials via 3D bioprinting technology. We highlighted the synergistic benefits of combining numerous nanomaterials into ECM hydrogels and imposing geometrical effects by 3D bioprinting technology. Furthermore, we also elaborated on critical issues remaining at the moment, such as the inhomogeneous dispersion of nanomaterials and consequent technical and practical issues, in the fabrication of complex 3D structures with nanobioinks and nanomaterials. Finally, we elaborated on plausible outlooks for facilitating the use of nanomaterials in biofabrication and advancing the function of engineered tissues.

Collagen Functionalization of Polymeric Electrospun Scaffolds to Improve Integration into Full-Thickness Wounds

Background: Electrospun fibers are widely studied in regenerative medicine for their ability to mimic the extracellular matrix (ECM) and provide mechanical support. In vitro studies indicated that cell adhesion and migration is superior on smooth poly(L-lactic acid) (PLLA) electrospun scaffolds and porous scaffolds once biofunctionalized with collagen. Methods: The in vivo performance of PLLA scaffolds with modified topology and collagen biofunctionalization in full-thickness mouse wounds was assessed by cellular infiltration, wound closure and re-epithelialization and ECM deposition. Results: Early indications suggested unmodified, smooth PLLA scaffolds perform poorly, with limited cellular infiltration and matrix deposition around the scaffold, the largest wound area, a significantly larger panniculus gape, and lowest re-epithelialization; however, by day 14, no significant differences were observed. Collagen biofunctionalization may improve healing, as collagen-functionalized smooth scaffolds were smallest overall, and collagen-functionalized porous scaffolds were smaller than non-functionalized porous scaffolds; the highest re-epithelialization was observed in wounds treated with collagen-functionalized scaffolds. Conclusion: Our results suggest that limited incorporation of smooth PLLA scaffolds into the healing wound occurs, and that altering surface topology, particularly by utilizing collagen biofunctionalization, may improve healing. The differing performance of the unmodified scaffolds in the in vitro versus in vivo studies demonstrates the importance of preclinical testing.

Application progress of nanotechnology in regenerative medicine of diabetes mellitus

In recent years, the development of diabetic regenerative medicine has led to new developments and progress for the clinical treatment of diabetes mellitus and its various complications. Besides, the emergence of nanotechnology has injected new vitality into diabetic regenerative medicine. Nano-stent provides an appropriate direction for the regeneration of islet β cells, retinal tissue, nerve tissue, and wound tissue cells. Conductive nanomaterials promote various tissues' growth. Many nanoparticles also promote wound healing and present other advantages that have solved many potential problems in the practical application of regenerative medicine. In this review, we will summarize the application of nanotechnology in diabetic regenerative medicine.

Nanoarchitectonics for Ultrathin Gold Films Deposited on Collagen Fabric by High-Power Impulse Magnetron Sputtering

Gold nanoparticles conjugated with collagen molecules and fibers have been proven to improve structure strength, water and enzyme degradation resistance, cell attachment, cell proliferation, and skin wound healing. In this study, high-power impulse magnetron sputtering (HiPIMS) was used to deposit ultrathin gold films (UTGF) and discontinuous island structures on type I collagen substrates. A long turn-off time of duty cycle and low chamber temperature of HiPIMS maintained substrate morphology. Increasing the deposition time from 6 s to 30 s elevated the substrate surface coverage by UTGF up to 91.79%, as observed by a field emission scanning electron microscope. X-ray diffractometry analysis revealed signature low and wide peaks for Au (111). The important surface functional groups and signature peaks of collagen substrate remained unchanged according to Fourier transform infrared spectroscopy results. Multi-peak curve fitting of the Amide I spectrum revealed the non-changed protein secondary structure of type I collagen, which mainly consists of α-helix. Atomic force microscopy observation showed that the roughness average value shifted from 1.74 to 4.17 nm by increasing the deposition time from 13 s to 77 s. The uneven surface of collagen substrate made quantification of thin film thickness by AFM difficult. Instead, UTGF thickness was measured using simultaneously deposited glass specimens placed in an HiPIMS chamber with collagen substrates. Film thickness was 3.99 and 10.37 nm at deposition times of 13 and 77 s, respectively. X-ray photoelectron spectroscopy showed preserved substrate elements on the surface. Surface water contact angle measurement revealed the same temporary hydrophobic behavior before water absorption via exposed collagen substrates, regardless of deposition time. In conclusion, HiPIMS is an effective method to deposit UTGF on biomedical materials such as collagen without damaging valuable substrates. The composition of two materials could be further used for biomedical purposes with preserved functions of UTGF and collagen.

Collagen based electrospun materials for skin wounds treatment

Materials used for wound care have evolved from simple covers to functional wound dressings with bioactive properties. Electrospun nanofibers show great similarity to the natural fibrillar structure of skin extracellular matrix (ECM); therefore, by mimic, the morphology of ECM, nanofibers show high potential for facilitating the healing of skin injuries. Besides morphology, scaffold composition is another important parameter in the production of bioactive wound dressings. Collagen type I is the main structural protein of skin ECM is biocompatible, biodegradable, and its extraction from animal sources is relatively simple. The fabrication of electrospun wound dressings based on collagen and its blends have been studied for skin tissue engineering applications. This review focus on the new advances of collagen electrospun materials for skin wound treatment. It summarizes the recent research on pristine collagen, collagen blends, and collagen surface modifications on nanofibers mats. Finally, the strategies for three-dimensional nanofibers production will also be discussed.

Nanofibrous cosmetic face mask for transdermal delivery of nano gold: synthesis, characterization, release and zebra fish employed toxicity studies

This study involves the generation of gold nanoparticles (Au NPs) via a novel natural/non-toxic methodology using tea and orange-peel extracts. These were then embedded into a novel blend composed of a polyethylene oxide and gelatin (PEO-Gel) fibre mat. The scanning electron microscopy results indicated that the addition of both collagen (COL) and ascorbic acid (AA) into the PEO-Gel system (PEO-Gel-AA-COL system) enhances the Au NP incorporation into nanofibres leading to a diameter of 164.60 ± 20.95 and 192.43 ± 39.14 nm in contrast to the spraying observed with the Au PEO-Gel system alone. Releasing studies conducted over 30 min indicated that the PEO-Gel-AA-COL-orange peel Au (OpAu) system accounts for a higher content of Au release than the green tea Au (GtAu) NP system where a maximum release could be attained within 10-30 min depending on the amount of Au NPs that have been incorporated. Moreover, the transdermal diffusion studies conducted using Strat membrane indicated that Au NPs from both formulations (PEO-Gel-AA-COL-GtAu nanofibre, PEO-Gel-AA-COL-OpAu nanofibre) have diffused through the stratum corneum and trapped in the dermis and epidermis indicating its transdermal deliverability. Additionally, 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay revealed that nanofibres have similar radical scavenging activity like AA standard. Toxicity evaluation on a zebra fish embryo model confirmed that both GtAu NPs and OpAu NPs do not induce any teratogenic activity and are safe to be used in the range of 1.0-167 µg ml-1.

Colloidal stability and biological activity evaluation of microbial exopolysaccharide levan-capped gold nanoparticles

The main objectives of this study were to explore the suitability of the exopolysaccharide levan, biosynthesized by Bacillus subtilis, to aid in the formation of gold nanoparticles (AuNPs) and to investigate the colloidal stability and in vitro biological activity of this biopolymer-AuNPs complex. AuNPs (mainly spherical, 8-10 nm-sized, and monodispersed) were successfully synthesized in levan concentrations up to 0.5% w/v (L-AuNP0.5) while exposed to ultraviolet C (UVC) irradiation. The increase of levan quantity decreased the size of AuNPs according to Transmission Electron Microscopy (TEM) images and enhanced the colloidal stability significantly. The presence of L-AuNP0.5 at the highest treatment dose (1000 μg/mL) exhibited substantial cytotoxicity towards L-929 mouse fibroblasts for all incubation periods. Dose-dependent toxicity was observed for the first day while, after this threshold value, medium (100 μg/mL) and the lowest (10 μg/mL) treatment doses were non-cytotoxic during 7 days of incubation, implying dose and time-independent cell viabilities (> 95%) compared to the negative control (complete cell culture medium). There occurred a special surface interaction with cells and L-AuNP0.5, especially when the cells were subjected to deliberate starvation periods to increase L-AuNP0.5 internalization via passive and active endocytosis. Scanning Electron Microscopy (SEM) images showed high accumulation of L-AuNP0.5 around or inside the cell membrane after 7 days. Overall, this attribute (high uptake of L-AuNP0.5) could make them promising candidates for prospective cancer therapeutics or drug delivery systems by enabling the cell internalization of anticancer drugs.

Nanostructured Materials for Artificial Tissue Replacements

This paper review current trends in applications of nanomaterials in tissue engineering. Nanomaterials applicable in this area can be divided into two groups: organic and inorganic. Organic nanomaterials are especially used for the preparation of highly porous scaffolds for cell cultivation and are represented by polymeric nanofibers. Inorganic nanomaterials are implemented as they stand or dispersed in matrices promoting their functional properties while preserving high level of biocompatibility. They are used in various forms (e.g., nano- particles, -tubes and -fibers)-and when forming the composites with organic matrices-are able to enhance many resulting properties (biologic, mechanical, electrical and/or antibacterial). For this reason, this contribution points especially to such type of composite nanomaterials. Basic information on classification, properties and application potential of single nanostructures, as well as complex scaffolds suitable for 3D tissues reconstruction is provided. Examples of practical usage of these structures are demonstrated on cartilage, bone, neural, cardiac and skin tissue regeneration and replacements. Nanomaterials open up new ways of treatments in almost all areas of current tissue regeneration, especially in tissue support or cell proliferation and growth. They significantly promote tissue rebuilding by direct replacement of damaged tissues.

Functional Skin Grafts: Where Biomaterials Meet Stem Cells

Skin tissue engineering has attained several clinical milestones making remarkable progress over the past decades. Skin is inhabited by a plethora of cells spatiotemporally arranged in a 3-dimensional (3D) matrix, creating a complex microenvironment of cell-matrix interactions. This complexity makes it difficult to mimic the native skin structure using conventional tissue engineering approaches. With the advent of newer fabrication strategies, the field is evolving rapidly. However, there is still a long way before an artificial skin substitute can fully mimic the functions and anatomical hierarchy of native human skin. The current focus of skin tissue engineers is primarily to develop a 3D construct that maintains the functionality of cultured cells in a guided manner over a period of time. While several natural and synthetic biopolymers have been translated, only partial clinical success is attained so far. Key challenges include the hierarchical complexity of skin anatomy; compositional mismatch in terms of material properties (stiffness, roughness, wettability) and degradation rate; biological complications like varied cell numbers, cell types, matrix gradients in each layer, varied immune responses, and varied methods of fabrication. In addition, with newer biomaterials being adopted for fabricating patient-specific skin substitutes, issues related to escalating processing costs, scalability, and stability of the constructs under in vivo conditions have raised some concerns. This review provides an overview of the field of skin regenerative medicine, existing clinical therapies, and limitations of the current techniques. We have further elaborated on the upcoming tissue engineering strategies that may serve as promising alternatives for generating functional skin substitutes, the pros and cons associated with each technique, and scope of their translational potential in the treatment of chronic skin ailments.

Skin wound regeneration with bioactive glass-gold nanoparticles ointment

The bioactive glasses can lead to the promotion of growth of granulation tissue, while the gold nanoparticles (AuNPs) can induce the acceleration of wound healing including tissue regeneration, connective tissue formation, and angiogenesis. The aim of this study was to evaluate the impact of using the bioactive glass (BG) and BG-AuNPs composites on skin wound healing in experimental rat models for 14 days. Sol-gel derived BGs and BG-AuNPs composites mixed with Vaseline at 6, 12 and 18 wt% were used to evaluate the repair response of the skin. During the process of healing, granulomatous reaction was observed in the wound treated with 12 and 18 wt% BG-Vaseline ointments. Furthermore, a strong vascular proliferation and complete wound regeneration were found in 18%BG-AuNPs-Vaseline treated groups. The results derived from the performed investigations revealed that the 18% BG-AuNPs-Vaseline ointment is a promising candidate for wound healing applications.

Biomaterials for Skin Substitutes

Patients with extensive burns rely on the use of tissue engineered skin due to a lack of sufficient donor tissue, but it is a challenge to identify reliable and economical scaffold materials and donor cell sources for the generation of a functional skin substitute. The current review attempts to evaluate the performance of the wide range of biomaterials available for generating skin substitutes, including both natural biopolymers and synthetic polymers, in terms of tissue response and potential for use in the operating room. Natural biopolymers display an improved cell response, while synthetic polymers provide better control over chemical composition and mechanical properties. It is suggested that not one material meets all the requirements for a skin substitute. Rather, a composite scaffold fabricated from both natural and synthetic biomaterials may allow for the generation of skin substitutes that meet all clinical requirements including a tailored wound size and type, the degree of burn, the patient age, and the available preparation technique. This review aims to be a valuable directory for researchers in the field to find the optimal material or combination of materials based on their specific application.

Collagen/gold nanoparticle nanocomposites: A potential skin wound healing biomaterial

In this study, nanocomposite collagen scaffolds incorporating gold nanoparticles (AuNPs) were prepared for wound healing applications. Initially, dose (<20 ppm) and size (>20 nm) of AuNPs that were not cytotoxic on HaCat keratinocytes and 3T3 fibroblasts were determined. Both collagen sponges and AuNP-incorporated nanocomposites (CS-Au) were cross-linked with glutaraldehyde (CS-X and CS-AuX). Incorporation of AuNPs into cross-linked scaffolds enhanced their stability against enzymatic degradation and increased the tensile strength. Hydrolytic degradation of CS-Au group was also less than CS after seven days. Upon confirming in vitro biocompatibility of the scaffolds with cytotoxicity assays, cell attachment and proliferation tests and the in vivo efficacy for healing of full-thickness skin wounds were investigated by applying CS-X, CS-AuX or a commercial product (Matriderm®) onto defect sites and covering with Ioban® drapes. Defects were covered only with drapes for untreated control group. The wound areas were examined with histopathological and biomechanical tests after 14 days of operation. CS-AuX group was superior to untreated control and Matriderm®; it suppressed the inflammation while significantly promoting granulation tissue formation. Inflammatory reaction against CS-AuX was milder than CS-X. Neovascularization was also higher in CS-AuX than other groups, though the result was not significant. Wound closure in CS-X (76%), CS-AuX (69%), and Matriderm® (65%) were better than untreated control (45%). CS-AuX group had the highest tensile strength (significantly higher than Matriderm®) and modulus (significantly higher than Matriderm® and CS-X), indicating a faster course of dermal healing. Further studies are also needed to investigate whether higher loading of AuNPs affects these results positively in a statistically meaningful manner. Overall, their contribution to the enhancement of degradation profiles and mechanical properties, their excellent in vitro biocompatibility, and tendency to accelerate wound healing are encouraging the use of AuNPs in collagen sponges as potent skin substitutes in the future.

Wet electrospun silk fibroin/gold nanoparticle 3D matrices for wound healing applications

The effectiveness of a silk fibroin/gold nanoparticle 3D nanofibrous matrix on a rat model of full-thickness dermal wound healing was investigated.