Facile preparation of fatigue-resistant Mxene-reinforced chitosan cryogel for accelerated hemostasis and wound healing

The development of highly effective chitosan-based hemostatic materials that can be utilized for deep wound hemostasis remains a considerable challenge. In this study, a hemostatic antibacterial chitosan/N-hydroxyethyl acrylamide (NHEMAA)/Ti3C2Tx (CSNT) composite cryogel was facilely prepared through the physical interactions between the three components and the spontaneous condensation of NHEMAA. Because of the formation of strong crosslinked network, the CSNT cryogel showed a developed pore structure (~ 99.07 %) and superfast water/blood-triggered shape recovery, enabling it to fill the wound after contacting the blood. Its capillary effect, amino groups, negative charges, and affinity with lipid collectively induced rapid hemostasis, which was confirmed by in vitro and in vivo analysis. In addition, CSNT cryogel showed excellent photothermal antibacterial activities, high biosafety, and in vivo wound healing ability. Furthermore, the presence of chitosan effectively prevented the oxidation of MXene, thus enabling the long-term storage of the MXene-reinforced cryogel. Thus, our hemostatic cryogel demonstrates promising potential for clinical application and commercialization, as it combines high resilience, rapid hemostasis, efficient sterilization, long-term storage, and easy mass production.

Magnetically actuated pandanus fruit-like nanorobots for enhanced pH-stimulated drug release and targeted biofilm elimination in wound healing

Conventional antibiotic treatment struggles to eliminate biofilms in wounds due to the formation compact barrier. Herein, we fabricate magnetic pandanus fruit-like nanorobots (NRs) that function as drug carriers while exhibit excellent maneuverability for enhanced antibacterial tasks. Specifically, zeolitic imidazolate framework-8 (ZIF-8) is self-assembled on the surface of Fe3O4 nanoparticles, loaded with a small quantity of ciprofloxacin, and covered with a layer of polydopamine (PDA). Energized by external magnetic fields, the NRs (F@Z/C/P) are steered in defined direction to penetrate the infection tissues, and effectively arrive targeted areas for pH stimulated drug release and near-infrared triggered phototherapy, contributing to an antibacterial rate of >99.9 %. The Zn2+ in ZIF-8 and the catechol group in PDA form catechol-ZIF-8-drug structures, which effectively reduce drug release by 11 % in high pH environments and promote rapid drug release by 14 % in low pH environments compared to NRs without PDA. Additionally, F@Z/C/P can remove the biofilms and bacteria in Staphylococcus aureus infected wounds, and eventually be discharged from the infected site after treatment, leading to faster healing with an intact epidermis and minimal harm to surrounding tissues and organs. The study provides a promising strategy for tackling biofilm-associated infections in vivo through the use of multi-functional NRs.

Oral Wound Healing: A Scoping Review and Proposal of a New Index for Palatal Mucosa

Purpose

The aim of this scoping review was to evaluate the wound healing indices available in literature and propose a new intra-oral wound healing index to assess the healing of palatal mucosa.

Materials and Methods

A PubMed database search was conducted to identify relevant studies using the search strategy: ('Oral Wound healing') OR ('Palatal tissue healing') OR ('Healing indices in Oral and Maxillofacial Surgery') OR ('Palatal wound healing') OR ('Complications in wound healing'). A qualitative and quantitative synthesis of the results was done and data was presented following the PRISMA-ScR guidelines.

Results

The search resulted in 9 articles published between 2019 and 2022, which were eligible for inclusion in the study. The data revealed that the indices currently available for the assessment of intra-oral healing were limited and primarily concerned with the assessment of gingival and periodontal tissues.

Conclusion

The healing indices devised for gingival and periodontal tissues cannot be applied to palatal healing due to the differences in clinical and histological aspects. Therefore, a new index to monitor the healing response specifically for the soft tissues in the palate has been proposed. This maybe particularly useful in cleft palate repair and other procedures performed over the palatal tissues.

Injectable plant-derived polysaccharide hydrogels with intrinsic antioxidant bioactivity accelerate wound healing by promoting epithelialization and angiogenesis

Skin wound healing is a complex and dynamic process involving hemostasis, inflammatory response, cell proliferation and migration, and angiogenesis. Currently used wound dressings remain unsatisfactory in the clinic due to the lack of adjustable mechanical property for injection operation and bioactivity for accelerating wound healing. In this work, an "all-sugar" hydrogel dressing is developed based on dynamic borate bonding network between the hydroxyl groups of okra polysaccharide (OP) and xyloglucan (XG). Benefiting from the reversible crosslinking network, the resulting composite XG/OP hydrogels exhibited good shear-thinning and fast self-healing properties, which is suitable to be injected at wound beds and filled into irregular injured site. Besides, the proposed XG/OP hydrogels showed efficient antioxidant capacity by scavenging DPPH activity of 73.9 %. In vivo experiments demonstrated that XG/OP hydrogels performed hemostasis and accelerated wound healing with reduced inflammation, enhanced collagen deposition and angiogenesis. This plant-derived dynamic hydrogel offers a facile and effective approach for wound management and has great potential for clinical translation in feature.

Hyaluronic acid-dopamine-NCSN hydrogel combined with extracellular matrix promotes wound healing

The skin barrier is essential to prevent pathogenic invasion. When injury occurs, multiple biological pathways are promptly activated and wound repair processes are triggered. The effective healing of wounds is essential to our survival, and dysfunction could result from aberrant wound repair. Preparation of many hydrogels, which involve the addition of growth/cell factors or mimic extracellular matrix (ECM) components, has not resulted in significant advances in tissue recovery. ECM contains a large number of biologically active molecules that activate a variety of cellular transduction pathways, which are essential for wound repair. Here, we prepared hyaluronic acid-dopamine-thiourea (HA-DA-NCSN) hydrogels exhibiting ultrafast gelation in situ, following the methods of Xu et al., and subsequently designed a hydrogel containing ECM particles. In addition, the loaded ECM material, specifically decellularized ECM material, not only enhanced the strength of the hydrogel network, but also delivered bioactive substances that make it a suitable platform for skin wound repair. The ECM hydrogel has great potential as an efficient bioactive wound dressing. Our research suggested that this strategy is likely to improve skin wound closure in rat skin wound models. This article is protected by copyright. All rights reserved.

Promising application of pulsed electromagnetic fields on tissue repair and regeneration

Tissue repair and regeneration is a vital biological process in organisms, which is influenced by various internal mechanisms and microenvironments. Pulsed electromagnetic fields (PEMFs) are becoming a potential medical technology due to its advantages of effectiveness and non-invasiveness. Numerous studies have demonstrated that PEMFs can stimulate stem cell proliferation and differentiation, regulate inflammatory reactions, accelerate wound healing, which is of great significance for tissue regeneration and repair, providing a solid basis for enlarging its clinical application. However, some important issues such as optimal parameter system and potential deep mechanisms remain to be resolved due to PEMFs window effect and biological complexity. Thus, it is of great importance to comprehensively summarizing and analyzing the literature related to the biological effects of PEMFs in tissue regeneration and repair. This review expounded the biological effects of PEMFs on stem cells, inflammation response, wound healing and musculoskeletal disorders in order to improve the application value of PEMFs in medicine. It is believed that with the continuous exploration of biological effects of PEMFs, it will be applied increasingly widely to tissue repair and other diseases.

Thiolation-Based Protein-Protein Hydrogels for Improved Wound Healing

The limitations of protein-based hydrogels, including their insufficient mechanical properties and restricted biological functions, arise from the highly specific functions of proteins as natural building blocks. A potential solution to overcome these shortcomings is the development of protein-protein hydrogels, which integrate structural and functional proteins. In this study, we introduce a protein-protein hydrogel formed by crosslinking bovine serum albumin (BSA) and a genetically engineered intrinsically disordered collagen-like protein (CLP) through Ag-S bonding. Our approach involves thiolating lysine residues of BSA and crosslinking CLP with Ag+ ions, utilizing thiolation of BSA and the free-cysteines of CLP. The resulting protein-protein hydrogels exhibit exceptional properties, including notable plasticity, inherent self-healing capabilities, and gel-sol transition in response to redox conditions. In comparison to standalone BSA hydrogels, these protein-protein hydrogels demonstrate enhanced cellular viability, and improved cellular migration. In vivo experiments provide conclusive evidence of accelerated wound healing, observed not only in murine models with streptozotocin (Step)-induced diabetes but also in zebrafish models subjected to UV-burn injuries. Detailed mechanistic insights, combined with assessments of pro-inflammatory cytokines and the expression of epidermal differentiation-related proteins, robustly validate the protein-protein hydrogel's effectiveness in promoting wound repair. This article is protected by copyright. All rights reserved.

Indocyanine green-loaded platelet activated by photodynamic and photothermal effects for selective control of wound repair

OBJECTIVE

Prompt and effective wound repair is an essential strategy to promote recovery and prevent infection in patients with various types of trauma. Platelets can release a variety of growth factors upon activation to facilitate revascularization and tissue repair, provided that their activation is uncontrollable. The present study is designed to explore the selective activation of platelets by photodynamic and photothermal effects (PDE/PTE) as well as the trauma repair mediated by PDE/PTE.

MATERIALS AND METHODS

In the current research, platelets were extracted from the blood of mice. Indocyanine green (ICG) was applied to induce PDE/PTE. The uptake of ICG by platelets was detected by laser confocal microscopy and flow cytometry. The cellular integrity was measured by microscopy. The reactive oxygen species (ROS) generation and temperature of platelets were assayed by 2,7-Dichlorodihydrofluorescein diacetate (DCFH-DA) and temperature detector. The activation of platelets was measured by western blots (WB), dynamic light scattering (DLS), and scanning electron microscopy (SEM). The release of growth factor was detected by enzyme-linked immuno sorbent assay (Elisa), wherein the in vitro cell proliferation was investigated by 5-Ethynyl-2'-deoxyuridine (EDU) assay. The wound infection rates model and histological examination were constructed to assay the ICG-loaded platelet-mediated wound repair.

RESULTS

Platelets could load with ICG, a kind of photodynamic and photothermal agent, as carriers and remain intact. Near-infrared (NIR) laser irradiation of ICG-loaded platelets (ICG@PLT) facilitated higher temperature and ROS generation, which immediately activated ICG@PLT, as characterized by increased membrane p-selectin (CD62p), cyclooxygenase-2 (COX-2), thromboxane A2 receptor (TXA2R) expression, elevated hydrated particle size, and prominent aggregation in platelets. Further investigation revealed that massive insulin-like growth factor (IGF) and platelet-derived growth factor (PDGF) were released from the activated ICG@PLT, which also promoted the proliferation of endothelial cells and keratinocytes in co-culture. In consequence, activated platelets and increased neovascularization could be observed in rats with wound infection treated by ICG@PLT in the presence of NIR. More impressively, the hydrogel containing ICG@PLT accelerated wound healing and suppressed inflammation under NIR, exhibiting excellent wound repair properties.

CONCLUSION

Taken together, the current work identified that platelets could be activated by PDE/PTE and thereby release growth factor, potentiating wound repair in a controlled manner.

Natural agents as wound-healing promoters

The management of acute and chronic wounds resulting from diverse injuries poses a significant challenge to clinical practices and healthcare providers. Wound healing is a complex biological process driven by a natural physiological response. This process involves four distinct phases, namely hemostasis, inflammation, proliferation, and remodeling. Despite numerous investigations on wound healing and wound dressing materials, complications still persist, necessitating more efficacious therapies. Wound-healing materials can be categorized into natural and synthetic groups. The current study aims to provide a comprehensive review of highly active natural animal and herbal agents as wound-healing promoters. To this end, we present an overview of in vitro, in vivo, and clinical studies that led to the discovery of potential therapeutic agents for wound healing. We further elucidated the effects of natural materials on various pharmacological pathways of wound healing. The results of previous investigations suggest that natural agents hold great promise as viable and accessible products for the treatment of diverse wound types.

Novel microneedle platforms for the treatment of wounds by drug delivery: A review

The management and treatment of wounds are complex and pose a substantial financial burden to the patient. However, the complex environment of wounds leads to inadequate drug absorption to achieve the desired therapeutic effect. As a novel technological platform, microneedles are widely used in drug delivery because of their multiple drug loading, multistage drug release, and multiple designs of topology. This study systematically summarizes and analyzes the manufacturing methods and limitations of different microneedles, as well as the latest research advances in pain management, drug delivery, and healing promotion, and presents the challenges and opportunities for clinical applications. On this basis, the development of microneedles in external wound repair and management is envisioned, and it is hoped that this study can provide guidelines for the design of microneedle systems in different application contexts, including the selection of materials, preparation methods, and structural design, to achieve better healing and regeneration results.

Biocompatible and biodegradable Bletilla striata polysaccharides hydrogels crosslinked by BDDE for wound healing through the regulating of macrophage polarization

Bletilla striata polysaccharide (BSP) is a naturally occurring polysaccharide that demonstrates notable biocompatibility and biodegradability. Additionally, BSP possesses therapeutic attributes, including anti-inflammatory and reparative actions. Herein, we report a novel BSP hydrogel prepared using 1,4-butanediol diglycidyl ether (BDDE) as a cross-linking agent. The hydrogel was synthesized via condensation of the hydroxyl group in the BSP molecule with the epoxy group in BDDE. This technique of preparation preserves BSP's natural properties while avoiding any potentially hazardous or adverse effects that may occur during the chemical alteration. Compared with BSP before crosslinking, BSP hydrogel has distinct advantages, such as a three-dimensional network structure, improved water retention, enhanced swelling capacity, greater thermal stability, and superior mechanical properties. Experiments on in vitro cytotoxicity, hemolysis, and degradation revealed that BSP hydrogel had good biocompatibility and biodegradability. Finally, we evaluated the in vivo wound repair effect of BSP hydrogel, and the results showed that BSP hydrogel had a significant wound-healing effect. Furthermore, the BSP hydrogel promoted the polarization of M1-type macrophages towards the M2-type and reduced the inflammatory response during the wound healing phase. Because of its ease of production, safety, efficacy, and environmental friendliness, BSP hydrogel is considered a highly promising material for wound dressings.

Genetically encoded zinc-binding collagen-like protein hybrid hydrogels for wound repair

Incorporating zinc oxide nanoparticles (ZnOnps) into collagen is a promising strategy for fabricating biomaterials with excellent antibacterial activity, but modifications are necessary due to the low zinc binding affinity of native collagen, which can cause disturbances to the functions of both ZnOnps and collagen and result in heterogeneous effects. To address this issue, we have developed a genetically encoded zinc-binding collagen-like protein, Zn-eCLP3, which was genetically modified by Scl2 collagen-like protein. Our study found that Zn-eCLP3 has a binding affinity for zinc that is 3-fold higher than that of commercialized type I collagen, as determined by isothermal titration calorimetry (ITC). Using ZnOnps-coordinated Zn-eCLP3 protein and xanthan gum, we prepared a hydrogel that showed significantly stronger antibacterial activity compared to a collagen hydrogel prepared in the same manner. In vitro cytocompatibility tests were conducted to assess the potential of the Zn-eCLP3 hydrogel for wound repair applications. In vivo experiments, which involved an S. aureus-infected mouse trauma model, showed that the application of the Zn-eCLP3 hydrogel resulted in rapid wound regeneration and increased expression of collagen-1α and cytokeratin-14. Our study highlights the potential of Zn-eCLP3 and the hybrid hydrogel for further studies and applications in wound repair.

Development of a bioactive silk fibroin bilayer scaffold for wound healing and scar inhibition

In cases of deep skin defects, spontaneous tissue regeneration and excessive collagen deposition lead to hyperplastic scars. Conventional remedial action after scar formation is limited with a high recurrence rate. In this study, we designed a new artificial skin bilayer using silk fibroin nanofibers films (SNF) as the epidermis, and silk fibroin (SF) / hyaluronic acid (HA) scaffold as the dermal layer. The regenerated SF film was used as a binder to form a functional SNF-SF-HA bilayer scaffold. The bilayer scaffold showed high porosity, hydrophilicity, and strength, and retained its shape over 30 days in PBS. In vitro, human umbilical vein endothelial cells were seeded into the bilayer scaffold and showed superior cell viability. In vivo analyses using the rabbit ear hypertrophic scar (HS) model indicated that the bilayer scaffold not only supported the reconstruction of new tissue, but also inhibited scar formation. The scaffold possibly achieved scar inhabitation by reducing wound contraction, weakening inflammatory reactions, and regulating collagen deposition and type conversion, which was partly observed through the downregulation of type I collagen, transforming growth factor-β, and α-smooth muscle actin. This study describes a new strategy to expand the application of silk-based biomaterials for the treatment of hyperplastic skin scars.

Heterogeneous Cu2O-SnO2 doped polydopamine fenton-like nanoenzymes for synergetic photothermal-chemodynamic antibacterial application

Wound infections caused by drug-resistant bacteria pose a great threat to human health, and the development of non-drug-resistant antibacterial approaches has become a research priority. In this study, we developed Cu2O-SnO2 doped polydopamine (CSPDA) triple cubic antibacterial nanoenzymes with high photothermal conversion efficiency and good Fenton-like catalase performance. CSPDA antibacterial nanoplatform can catalyze the generation of hydroxyl radical (·OH) from H2O2 at low concentration (50 μg∙mL-1) under 808 nm near-infrared (NIR) irradiation to achieve a combined photothermal therapy (PTT) and chemodynamic therapy (CDT). And the CSPDA antibacterial nanoplatform displays broad-spectrum and long-lasting antibacterial effects against both Gram-negative Escherichia coli (100 %) and Gram-positive Staphylococcus aureus (100 %) in vitro. Moreover, in a mouse wound model with mixed bacterial infection, the nanoplatform demonstrates a significant in vivo bactericidal effect while remaining good cytocompatible. To conclude, this study successfully develops an efficient and long-lasting bacterial infection treatment system. This system provided different options for future studies on the design of synergistic antimicrobial therapy. Hence, the as-synthesized synergetic photothermal therapy and chemodynamic therapy nanoenzymes have rapid and long-term bactericidal ability, well-conglutinant performance and effectively preventing wound infection for clinical application. STATEMENT OF SIGNIFICANCE: Wound infections caused by drug-resistant bacteria pose a great threat to human health, and the development of non-drug-resistant antibacterial approaches has become a research priority. In this study, we developed Cu2O-SnO2 doped polydopamine (CSPDA) triple cubic yolk-like antibacterial nanoenzymes with high photothermal conversion efficiency and Fenton-like catalase effect for photothermal and Chemodynamic antibacterial therapy, Meanwhile, the nanocomposites exhibit good antibioadhesion in a natural water environment for a long-time immersion. In conclusion, this study successfully develops an efficient and long-lasting bacterial infection treatment system. These findings present a pioneering strategy for future research on the design of synergistic antibacterial and antibioadhesive systems.

A multifunctional and self-adaptive double-layer hydrogel dressing based on chitosan for deep wound repair

Hydrogel wound dressing for irregular shape and deep wound repair is a research hotspot. Herein, a multifunctional and self-adaptive double-layer hydrogel was constructed, which was comprised of chitosan-based inner layer hydrogel and gellan gum-based outer layer hydrogel. Various properties of inner layer hydrogel were systematically investigated, including injectability, shape-adaptability, solid-liquid phase transition, biocompatibility, hemostasis, antibacterial performance and anti-inflammatory. Thanks to the phase-transition from solid to liquid at body temperature, inner layer hydrogel exhibited stronger adaptability to fill irregular and deep wounds, in which chitosan was liquefied and its therapeutic effect was maximized. Outer layer hydrogel was fabricated by calcium ions and gellan gum, whose certain mechanical strength could provide protection and a moister environment for wounds. Because of these characteristics, double-layer hydrogel markedly promoted skin tissue regeneration and wound closure and thereby possessed potential clinical application prospect as wound dressing for deep wounds.

Advantage effect of Dalbergia pinnata on wound healing and scar formation of burns

ETHNOPHARMACOLOGICAL RELEVANCE

Dalbergia pinnata, as a natural and ethnic medicine in China, has been used for burns and wounds with a long history, which has the effect of invigorating blood and astringent sores. However, there were no reports on the advantage activity of burns.

AIM OF STUDY

The purpose of this study was to screen out the best active extract part of Dalbergia pinnata and investigate its therapeutic effect on wound healing and scar resolution.

MATERIALS AND METHODS

Rat burn model was established and the healing effects of extracts from Dalbergia pinnata on burn wounds were evaluated by the percentage of wound contraction and period of epithelialization. Histological observation, immunohistochemistry, immunofluorescence and ELISA were used for the examination of inflammatory factors, TGF-β1, neovascularization and collagen fibers through the period of epithelialization. In addition, the effect of the optimal extraction site on fibroblast cells was evaluated by cell proliferation and cell migration assays. The extracts of Dalbergia pinnata were analyzed by UPLC-Q/TOF-MS or GC-MS technique.

RESULTS

Compared to the model group, there were better wound healing, suppressed inflammatory factors, more neovascularization as well as newly formed collagen in the ethyl acetate extract (EAE) and petroleum ether extract (PEE) treatment groups. The ratio of Collagen I and Collagen III was lower in the EAE and PEE treatment groups, suggesting a potential for reduced scarring. Furthermore, EAE and PEE could repair wounds by up-regulating TGF-β1 in the early stage of wound repair and down-regulating TGF-β1 in the late stage. In vitro studies showed that both EAE and PEE were able to promote NIH/3T3 cells proliferation and migration compared with the control group.

CONCLUSIONS

In this study, EAE and PEE were found to significantly accelerate wound repair and might have an inhibitory effect on the generation of scars. It was also hypothesized that the mechanism might be related to the regulation of TGF-β1 secretion. This study provided an experimental basis for the development of topical drugs for the treatment of burns with Dalbergia pinnata.

Risk of wound infection with use of sterile versus clean gloves in wound repair at the Emergency Department: A systematic review and meta-analysis

STUDY OBJECTIVE

Sterile gloves are widely used during wound repair procedures in Emergency Departments (ED) worldwide. It is unclear whether sterile gloves protect against postoperative wound infections. We conducted a systematic review and meta-analysis to determine if sterile gloves offer significant protection against wound infections compared to clean gloves for wound repair in the ED.

METHODS

Ovid MEDLINE, Ovid Embase, Cochrane Library and Web Of Science were searched for randomised controlled trials (RCTs) or non-randomized studies of intervention (NRSIs) from their dates of inception to January 2023. RCTs or NRSIs comparing sterile (control) vs. clean/no (intervention) glove use for wound repair procedures in the ED and reporting postoperative wound infections were included. Two investigators independently extracted data and assessed risk-of-bias of each report on a standardised form. Wound infection incidence was pooled using a random effects model. Subgroup analysis was performed to explore heterogeneity.

RESULTS

7 studies were included in the review, with 6 included in the meta-analysis. Of 3227 patients, 115/1608 (7.2%) patients in the intervention group and 135/1619 (8.3%) patients in the control group had postoperative wound infections. Overall RR was 0.86 (95% CI,0.67-1.10, I2=3.6%), and of high evidence certainty (GRADE). Absence of a protective effect was invariant in sensitivity analyses, leave-one-out analysis and subgroup analyses.

CONCLUSION

No evidence of additional protection against wound infections with the use of sterile gloves for wound repair in the ED compared to clean gloves was found. However, the review was limited by nonreporting of antibiotic history and time between wound repair and follow-up amongst included studies. Considering the ergonomics, potential cost-savings and environmental impact, clean gloves are a viable alternative to sterile gloves, without compromising wound infection risk in this setting.

Bioengineered skin constructs based on mesenchymal stromal cells and acellular dermal matrix exposed to inflammatory microenvironment releasing growth factors involved in skin repair

BACKGROUND

Skin tissue engineering is a rapidly evolving field of research that effectively combines stem cells and biological scaffolds to replace damaged tissues. Human Wharton's jelly mesenchymal stromal cells (hWJ-MSCs) are essential to generate tissue constructs, due to their potent immunomodulatory effects and release of paracrine factors for tissue repair. Here, we investigated whether hWJ-MSC grown on human acellular dermal matrix (hADM) scaffolds and exposed to a proinflammatory environment maintain their ability to produce in vitro growth factors involved in skin injury repair and promote in vivo wound healing.

METHODS

We developed a novel method involving physicochemical and enzymatic treatment of cadaveric human skin to obtain hADM scaffold. Subsequently, skin bioengineered constructs were generated by seeding hWJ-MSCs on the hADM scaffold (construct 1) and coating it with human platelet lysate clot (hPL) (construct 2). Either construct 1 or 2 were then incubated with proinflammatory cytokines (IL-1α, IL-1β, IL-6, TNF-α) for 12, 24, 48, 72 and 96 h. Supernatants from treated and untreated constructs and hWJ-MSCs on tissue culture plate (TCP) were collected, and concentration of the following growth factors, bFGF, EGF, HGF, PDGF, VEGF and Angiopoietin-I, was determined by immunoassay. We also asked whether hWJ-MSCs in the construct 1 have potential toward epithelial differentiation after being cultured in an epithelial induction stimulus using an air-liquid system. Immunostaining was used to analyze the synthesis of epithelial markers such as filaggrin, involucrin, plakoglobin and the mesenchymal marker vimentin. Finally, we evaluated the in vivo potential of hADM and construct 1 in a porcine full-thickness excisional wound model.

RESULTS

We obtained and characterized the hADM and confirmed the viability of hWJ-MSCs on the scaffold. In both constructs without proinflammatory treatment, we reported high bFGF production. In contrast, the levels of other growth factors were similar to the control (hWJ-MSC/TCP) with or without proinflammatory treatment. Except for PDGF in the stimulated group. These results indicated that the hADM scaffold maintained or enhanced the production of these bioactive molecules by hWJ-MSCs. On the other hand, increased expression of filaggrin, involucrin, and plakoglobin and decreased expression of vimentin were observed in constructs cultured in an air-liquid system. In vivo experiments demonstrated the potential of both hADM and hADM/hWJ-MSCs constructs to repair skin wounds with the formation of stratified epithelium, basement membrane and dermal papillae, improving the appearance of the repaired tissue.

CONCLUSIONS

hADM is viable to fabricate a tissue construct with hWJ-MSCs able to promote the in vitro synthesis of growth factors and differentiation of these cells toward epithelial lineage, as well as, promote in a full-thickness skin injury the new tissue formation. These results indicate that hADM 3D architecture and its natural composition improved or maintained the cell function supporting the potential therapeutic use of this matrix or the construct for wound repair and providing an effective tissue engineering strategy for skin repair.

Regulatory T cells in skin regeneration and wound healing

As the body's integumentary system, the skin is vulnerable to injuries. The subsequent wound healing processes aim to restore dermal and epidermal integrity and functionality. To this end, multiple tissue-resident cells and recruited immune cells cooperate to efficiently repair the injured tissue. Such temporally- and spatially-coordinated interplay necessitates tight regulation to prevent collateral damage such as overshooting immune responses and excessive inflammation. In this context, regulatory T cells (Tregs) hold a key role in balancing immune homeostasis and mediating cutaneous wound healing. A comprehensive understanding of Tregs' multifaceted field of activity may help decipher wound pathologies and, ultimately, establish new treatment modalities. Herein, we review the role of Tregs in orchestrating the regeneration of skin adnexa and catalyzing healthy wound repair. Further, we discuss how Tregs operate during fibrosis, keloidosis, and scarring.

Cell electrospinning and its application in wound healing: principles, techniques and prospects

Currently, clinical strategies for the treatment of wounds are limited, especially in terms of achieving rapid wound healing. In recent years, based on the technique of electrospinning (ES), cell electrospinning (C-ES) has been developed to better repair related tissues or organs (such as skin, fat and muscle) by encapsulating living cells in a microfiber or nanofiber environment and constructing 3D living fiber scaffolds. Therefore, C-ES has promising prospects for promoting wound healing. In this article, C-ES technology and its advantages, the differences between C-ES and traditional ES, the parameters suitable for maintaining cytoactivity, and material selection and design issues are summarized. In addition, we review the application of C-ES in the fields of biomaterials and cells. Finally, the limitations and improved methods of C-ES are discussed. In conclusion, the potential advantages, limitations and prospects of C-ES application in wound healing are presented.

Mesenchymal stem cell-derived extracellular vesicles in skin wound healing: roles, opportunities and challenges

Skin wounds are characterized by injury to the skin due to trauma, tearing, cuts, or contusions. As such injuries are common to all human groups, they may at times represent a serious socioeconomic burden. Currently, increasing numbers of studies have focused on the role of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) in skin wound repair. As a cell-free therapy, MSC-derived EVs have shown significant application potential in the field of wound repair as a more stable and safer option than conventional cell therapy. Treatment based on MSC-derived EVs can significantly promote the repair of damaged substructures, including the regeneration of vessels, nerves, and hair follicles. In addition, MSC-derived EVs can inhibit scar formation by affecting angiogenesis-related and antifibrotic pathways in promoting macrophage polarization, wound angiogenesis, cell proliferation, and cell migration, and by inhibiting excessive extracellular matrix production. Additionally, these structures can serve as a scaffold for components used in wound repair, and they can be developed into bioengineered EVs to support trauma repair. Through the formulation of standardized culture, isolation, purification, and drug delivery strategies, exploration of the detailed mechanism of EVs will allow them to be used as clinical treatments for wound repair. In conclusion, MSC-derived EVs-based therapies have important application prospects in wound repair. Here we provide a comprehensive overview of their current status, application potential, and associated drawbacks.

Sequential treatment for diabetic foot ulcers in dialysis patients: A case report

BACKGROUND

Diabetic foot ulcers (DFUs) are common in patients with diabetes, especially those undergoing hemodialysis. In severe cases, these ulcers can cause damage to the lower extremities and lead to amputation. Traditional treatments such as flap transposition and transfemoral amputation are not always applicable in all cases. Therefore, there is a need for alternative treatment methods.

CASE SUMMARY

This report describes a 62-year-old female patient who was admitted to the hospital with plantar and heel ulcers on her left foot. The patient had a history of renal failure and was undergoing regular hemodialysis. Digital subtraction angiography showed extensive stenosis and occlusion in the left superficial femoral artery, left peroneal artery and left posterior tibial artery. Following evaluation by a multidisciplinary team, the patient was diagnosed with type 2 DFUs (TEXAS 4D). Traditional treatments were deemed unsuitable, and the patient was treated with endovascular surgery in the affected area, in addition to supportive medical treatment, local debridement, and sequential repair using split-thickness skin and tissue-engineered skin grafts combined with negative pressure treatment. After four months, the wound had completely healed, and the patient was able to walk with a walking aid.

CONCLUSION

This study demonstrates a new treatment method for DFUs was successful, using angioplasty, skin grafts, and negative pressure.

Nanosilver alleviates foreign body reaction and facilitates wound repair by regulating macrophage polarization

Foreign body reactions induced by macrophages often cause delay or failure of wound healing in the application of tissue engineering scaffolds. This study explores the application of nanosilver (NAg) to reduce foreign body reactions during scaffold transplantation. An NAg hybrid collagen-chitosan scaffold (NAg-CCS) was prepared using the freeze-drying method. The NAg-CCS was implanted on the back of rats to evaluate the effects on foreign body reactions. Skin tissue samples were collected for histological and immunological evaluation at variable intervals. Miniature pigs were used to assess the effects of NAg on skin wound healing. The wounds were photographed, and tissue samples were collected for molecular biological analysis at different time points post-transplantation. NAg-CCS has a porous structure and the results showed that it could release NAg constantly for two weeks. The NAg-CCS group rarely developed a foreign body reaction, while the blank-CCS group showed granulomas or necrosis in the subcutaneous grafting experiment. Both matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were reduced significantly in the NAg-CCS group. The NAg-CCS group had higher interleukin (IL)-10 and lower IL-6 than the blank CCS group. In the wound healing study, M1 macrophage activation and inflammatory-related proteins (inducible nitric oxide synthase (iNOS), IL-6, and interferon-‍γ (IFN-‍γ)) were inhibited by NAg. In contrast, M2 macrophage activation and proinflammatory proteins (arginase-1, major histocompatibility complex-II (MHC-II), and found in inflammatory zone-1 (FIZZ-1)) were promoted, and this was responsible for suppressing the foreign body responses and accelerating wound healing. In conclusion, dermal scaffolds containing NAg suppressed the foreign body reaction by regulating macrophages and the expression of inflammatory cytokines, thereby promoting wound healing.

Multifunctional antibacterial bioactive nanoglass hydrogel for normal and MRSA infected wound repair

Large-scale skin damage brings potential risk to patients, such as imbalance of skin homeostasis, inflammation, fluid loss and bacterial infection. Moreover, multidrug resistant bacteria (MDRB) infection is still a great challenge for skin damage repair. Herein, we developed an injectable self-healing bioactive nanoglass hydrogel (FABA) with robust antibacterial and anti-inflammatory ability for normal and Methicillin-resistant Staphylococcus aureus (MRSA) infected skin wound repair. FABA hydrogel was fabricated facilely by the self-crosslinking of F127-CHO (FA) and alendronate sodium (AL)-decorated Si-Ca-Cu nanoglass (BA). FABA hydrogel could significantly inhibit the growth of Staphylococcus aureus, Escherichia coli and MRSA in vitro, while showing good cytocompatibility and hemocompatibility. In addition, FABA hydrogel could inhibit the expression of proinflammatory factor TNF-α and enhance the expression of anti-inflammatory factor IL-4/ IL-10. Based on its versatility, FABA hydrogel could complete wound closure efficiently (75% at day 3 for normal wound, 70% at day 3 for MRSA wound), which was almost 3 times higher than control wound, which was related with the decrease of inflammatory factor in early wound. This work suggested that FABA hydrogel could be a promising dressing for acute and MRSA-infected wound repair.

Multi-layer-structured bioactive glass nanopowder for multistage-stimulated hemostasis and wound repair

Current treatments for full-thickness skin injuries are still unsatisfactory due to the lack of hierarchically stimulated dressings that can integrate the rapid hemostasis, inflammation regulation, and skin tissue remodeling into the one system instead of single-stage boosting. In this work, a multilayer-structured bioactive glass nanopowder (BGN@PTE) is developed by coating the poly-tannic acid and ε-polylysine onto the BGN via facile layer-by-layer assembly as an integrative and multilevel dressing for the sequential management of wounds. In comparison to BGN and poly-tannic acid coated BGN, BGN@PTE exhibited the better hemostatic performance because of its multiple dependent approaches to induce the platelet adhesion/activation, red blood cells (RBCs) aggregation and fibrin network formation. Simultaneously, the bioactive ions from BGN facilitate the regulation of the inflammatory response while the poly-tannic acid and antibacterial ε-polylysine prevent the wound infection, promoting the wound healing during the inflammatory stage. In addition, BGN@PTE can serve as a reactive oxygen species scavenger, alleviate the oxidation stress in wound injury, induce the cell migration and angiogenesis, and promote the proliferation stage of wound repair. Therefore, BGN@PTE demonstrated the significantly higher wound repair capacity than the commercial bioglass dressing Dermlin™. This multifunctional BGN@PTE is a potentially valuable dressing for full-thickness wound management and may be expected to extend to the other wounds therapy.

Red LED light therapy associated with epidermal growth factor on wound repair process in rats

Epidermal growth factor (EGF) and light-emitting diode (LED) are currently deployed as promissory treatments for skin repair; however, the mechanisms of their association are not yet evidenced. Thus, the present study aimed to evaluate the effects of combined treatment with EGF and red LED on the wound healing processes in rats. Adult Wistar rats were randomized in control group (CG) wounds without treatment; wounds submitted to EGF treatment (EGF); wounds submitted to LED treatment (LED); wounds submitted to EGF associated with LED treatments (EGF/LED). Treatments were performed immediately after the surgical procedure and each 24 h, totaling 8 sessions. Moreover, LED was applied before EGF treatment at a single point in the center of the wound. Morphological characteristics and the immunoexpression of COX-2, VEGF, and TGF-β were measured. The results demonstrated that EGF/LED group presented a higher wound healing index. Additionally, all experimental groups presented similar findings in the histological evaluation, the degree of inflammation, and the area of dermis-like tissue. However, for EGF-treated animals (with or without LED), neoepithelial length was higher. Furthermore, all the treated groups decreased COX-2 and increased VEGF immunoexpression, and only EGF/LED group enhanced the TGF-β protein expression when compared to the untreated group. This research shows that EGF and LED modulate inflammatory process and increase the vascularity. In addition, treatment of EGF associated with LED promoted a more evident positive effect for increasing TGF-β expression and may be promising resources in the clinical treatment of cutaneous wounds.

Stability and biosafety of human epidermal stem cell for wound repair: preclinical evaluation

BACKGROUND

Cell therapy is a key technology to prevent sacrificing normal skin. Although some studies have shown the promise of human epidermal stem cells (EpiSCs), the efficacy, biosafety and quality control of EpiSC therapy have not been systematically reported.

METHODS

The biosafety, stemness maintenance and wound repair of EpiSC were systematically verified by in vitro and in vivo experiments. EpiSC were prepared from the foreskin using a collagen type IV rapid adherence method. The EpiSCs were identified by flow cytometry, immunofluorescence staining and cell morphology. The well-growing passage 1 (P1) EpiSCs were used to determine the proliferation curve (counting method). EpiSC clone formation assay was performed by Giemsa staining. Nude mice were used to prepare a full-thickness skin defect wound model to detect the repair effect of EpiSCs. The biosafety of EpiSCs was double tested in vitro and in vivo.

RESULTS

The results showed that the expression of specific markers and clone formation efficiency was stable when passage 1 (P1) to P8 cells were cultured, and the stemness rate of P8 cells was close to 85.1%. EpiSCs were expanded in vitro for 25 days, the number of cells reached 2.5 × 10⁸, and the transplantable area was approximately 75% of the total body surface area (TBSA). At 45 days, the total number of cells was approximately 30 billion, and the transplantable area was approximately the size of a volleyball court. A nude mouse wound model indicated that EpiSCs could rapidly close a wound. On postinjury day 7, the wound epithelialization rate in the cell transplantation group was significantly higher than that in the NaCl group (P < 0.05). In vitro, cell senescence increased, and telomerase activity decreased in P1 to P8 EpiSCs. In vivo, there were no solid tumors or metastatic tumors after EpiSC (P8) transplantation. In addition, the quality control of cultured cells met the clinical application criteria for cell therapy.

CONCLUSION

This preclinical study showed the stability and biosafety of human EpiSC therapy for wound repair.

Polydopamine-doped supramolecular chiral hydrogels for postoperative tumor recurrence inhibition and simultaneously enhanced wound repair

Cancer recurrence remains a major challenge after primary tumor excision, and the inflammation of tumor-caused wounds can hinder wound healing and potentially promote tumor growth. Herein, a chiral L-phenylalanine-based (LPFEG) supramolecular hydrogel system encapsulated with polydopamine nanoparticles (PDA-NPs) has been developed in order to prevent tumor relapse after surgery and promote wound repair. PDA-NPs allow for near-infrared (NIR) light-triggered photothermal therapy, especially, it can scavenge free radicals in the surgical wound. LPFEG can mimic native extracellular matrix (ECM) structure to create a chiral microenvironment that enhances fibroblast adhesion, proliferation, and new tissue regeneration. With anticancer drug doxorubicin (DOX) loaded into the composite hydrogel, the antitumor effect is significantly enhanced by the integration of chemo-photothermal therapy both in vitro and in vivo. The PDA-based chiral supramolecular composite hydrogel as an effective postoperative adjuvant possesses promising applicable prospects in inhibiting tumor recurrence and accelerating wound healing after operation. STATEMENT OF SIGNIFICANCE: After primary tumor excision, cancer recurrence remains a severe concern, and the inflammation induced by tumor-related wounds can delay wound healing. Herein, we designed a chiral L-phenylalanine-based (LPFEG) supramolecular hydrogel platform that was co-assembled with polydopamine nanoparticles (PDA-NPs). Among them, PDA-NPs can offer photothermal therapy and scavenge free radicals in surgical wounds. LPFEG can create a chiral microenvironment that promotes fibroblast adhesion, proliferation, and new tissue regeneration. Furthermore, with anticancer drug doxorubicin (DOX) loaded into the composite hydrogel, the antitumor effect is considerably boosted. Therefore, the PDA-based chiral supramolecular hydrogel shows high application potential as a postoperative adjuvant in preventing tumor relapse as well as accelerating wound healing after surgery.

Aminated β-Glucan with immunostimulating activities and collagen composite sponge for wound repair

Immunostimulating activities of yeast β(1 → 3)-D-Glucan (β-Glucan) mainly depended on its structures. However, due to the tight triple helix structure of β-Glucan, its immunostimulating activity is greatly weakened. Therefore, in order to partially unwind the tight triple helix structure of β-glucan and improve its solubility in the medium, we modified it by amination in this study (A-Glu). The results showed that A-Glu could stimulate Raw264.7 macrophages and significantly enhance its TNF-α, IL-6, and IL-10 cytokine expression levels in vitro. A-Glu could also induce a shift of M0 Raw264.7 toward M1, and M2 toward M1. To expand the application of A-Glu in wound repair, the composite sponge consisting of A-Glu and type I collagen via the formation of a stable polyion complex (PIC) was developed. Moreover, the composite sponge could accelerate wound repair significantly. These results reveal that soluble A-Glu as an immunostimulating agent has potential applications in biomedicine.

Extraction kinetic model of polysaccharide from Codonopsis pilosula and the application of polysaccharide in wound healing

The crude polysaccharide (CPNP) of Codonopsis pilosula was obtained by hot-water extraction technology. The extraction kinetic model established according to Fick's first law of diffusion and related parameters of polysaccharide was studied. CPNP microcapsules were prepared by blending with sodium alginate, Ca2+ ions and crude CPNP. The quality control (Drug loading rate, embedding rate and release rate, etc) of CPNP microcapsules were analyzed by pharmacopeas standards. The structure feature of CPNP microcapsules also were determined with various methods. The wound healing ability of CPNP microcapsules loading with different concentration of CPNP was evaluated using the rat wound model. The activity of various enzymes and the expression levels of pro-inflammatory factors in the model skin tissue also were determined by enzyme linked immunosorbent assay (ELISA). Hematoxylin-eosin staining (HE), Masson, immunohistochemistry were used to investigate the external application effect of CPNP microcapsules on skin wound repair. The extraction kinetics of CPNP was established with the linear correlation coefficient (R2) of 0.83-0.93, implied that the extraction process was fitted well with the Fick's first law of diffusion. The CPNP has good compatibility with sodium alginate and Ca2+ ions by SEM and TEM observation, and the particle size of CPNP microcapsules was 21.25±2.84 μm with the good degradation rate, loading rate (61.59%) and encapsulation rate (55.99%), maximum swelling rate (397.380 ±25.321%). Compared with control group, the redness, and swelling, bleeding, infection, and exudate of the damaged skin decreased significantly after CPNP microcapsules treatment, and the CPNP microcapsules groups exhibited good wound healing function with less inflammatory cell infiltration. The pathological structure showed that in the CPNP microcapsules group, more newborn capillaries, complete skin structure, and relatively tight and orderly arrangement of collagen fibers were observed in the skin of rats. CPNP microcapsules could effectively inhibit the high expression of pro-inflammatory factors in damaged skin, and significantly increase the contents of related enzymes (GSH-Px, T-AOC, LPO) and collagen fibers. The relative expression levels of genes (VEGF and miRNA21) in the CPNP microcapsules group were higher than those in the model group and the negative group. The above results suggested that the CPNP microcapsules could controlled-release the CPNP to the wound surface, and then played a better role in antibacterial, anti-inflammatory and skin wound repair.

In situ-formed adhesive hyaluronic acid hydrogel with prolonged amnion-derived conditioned medium release for diabetic wound repair

Hydrogels have long been used for encapsulating stem cell-derived conditioned mediums to achieve skin regeneration after wounding. However, inappropriate mechanical strength, low adhesion and low elasticity limit their clinical application. To address these challenges, we engineered a hyaluronic acid-based hydrogel grafted with methacrylic anhydride and N-(2-aminoethyl)-4-[4-(hydroxymethyl)-2-methoxy-5-nitrophenoxy]-butanamide (NB) groups to encapsulate a lyophilized amnion-derived conditioned medium (AM-CM). This hydrogel can photopolymerize in situ within 3 s by photo-initiated free-radical crosslinking between methacrylate moieties. Meanwhile, the formed o-nitrosobenzaldehyde groups by photo-irradiation could covalently bond with the amino groups of tissue surface, which allowed strong tissue adhesion. Furthermore, the hydrogel possessed excellent mechanical properties, high elasticity, favorable biocompatibility and prolonged AM-CM release. Our further vitro and in vivo studies showed that the hydrogel significantly accelerated diabetic wound healing by regulating macrophage polarization and promoting angiogenesis. The engineered hydrogel with AM-CM release has high potential to treat chronic wounds in clinics.

Mussel-Inspired Epoxy Bioadhesive with Enhanced Interfacial Interactions for Wound Repair

The balance between high mechanical properties and strong adhesion strength is crucial in designing and preparing a bio-based hydrogel adhesive for wound closure. Although the adhesion performance of bioadhesives has been remarkably improved by modification with catechol groups, their mechanical properties are yet to meet the biomedical requirements. In this study, mussel-inspired epoxy bioadhesives (CSD-PEG) were synthesized based on catechol-modified chitosan oligosaccharide (CSD) and polyethylene glycol diglycidyl ether (PEGDGE) through nucleophilic substitution. Notably, the CSD-PEG adhesive showed high mechanical and adhesion strengths, which were up to 50.7 kPa and 136.7 kPa, respectively. It was confirmed that a certain amount of the epoxy and catechol groups provided multiple interfacial interactions among the adhesives, substrates, and polymer chains for enhancing the performance of adhesives. The adhesives showed good binding and repairing effects for wound closure and favorable biocompatibility in vivo. The prepared CSD-PEG adhesives are expected to be a promising candidate for surgical tissue repair, wound closure, and tissue engineering fields. STATEMENT OF SIGNIFICANCE: Current reported adhesives composed of biopolymers generally suffer from poor mechanical properties or weak tissue adhesiveness. Therefore, to achieve simultaneously high mechanical and adhesion properties in a bio-based adhesive for wound closure is a big challenge. In this study, mussel-inspired adhesive hydrogels (CSD-PEG) were prepared based on catechol-modified chitosan oligosaccharide (CSD) and polyethylene glycol diglycidyl ether (PEGDGE). The tensile strength and adhesive strength of CSD-PEG on porcine skin reached 50.7 kPa and 136.7 kPa, respectively, which were higher than those for most reported biopolymeric adhesives, mainly due to the multiple interfacial interactions between the catechol and epoxy groups. The CSD-PEG bioadhesives also showed good binding and repairing effects for wound closure and tissue regeneration in vivo.

A platelet-derived hydrogel improves neovascularisation in full thickness wounds

Platelets are a reservoir of growth factors, cytokines and chemokines involved in spontaneous wound repair. In this study, a platelet-rich and fibrin-rich hydrogel was generated from expired platelet components that would have otherwise been transfused. The material contained physiological concentrations of transforming growth factor β1 (TGF-β1, platelet-derived growth factor AB (PDGF-AB), PDGF-BB, insulin-like growth factor-1 (IGF-1), fibroblast growth factor 2 (FGF-2), and epidermal growth factor (EGF). The effect of the hydrogel on wound repair was investigated in SKH-1 mice. Full thickness dorsal wounds were created on the mice and treated with the hydrogel at various concentrations. Immunohistochemical staining with CD31 (endothelial cell marker) revealed that wounds treated with the hydrogel showed significantly enhanced vascularisation in the wound bed. Moreover, high levels of interleukin-6 (IL-6) and KC (IL-8 functional homologue) in treated wounds were sustained over a longer period of time, compared to untreated wounds. We postulate that sustained IL-6 is a driver, at least partly, of enhanced vascularisation in full thickness wounds treated with the hydrogel. Future work is needed to explore whether this hydrogel can be utilised as a treatment option when vascularisation is a critical limitation. STATEMENT OF SIGNIFICANCE: The economic cost of wound repair is estimated in billions of dollars each year. In many cases time required to vascularise wounds is a major contributor to slow wound repair. In this study, we developed a blood-derived platelet- and fibrin-rich hydrogel. It contains a number of growth factors actively involved in spontaneous wound healing. This hydrogel significantly improved dermal repair and vascularisation in a full-thickness wound mouse model. This study provides an action mechanism for modulation of localised inflammation.

Regulating the mechanics of silk fibroin scaffolds promotes wound vascularization

Functional blood vessels are crucial to wound healing, and faster vascularization means faster tissue repair to some extent. Increasing numbers of pro-vascularization wound coverings are being developed and studied. Moreover, mechanical properties of the extracellular matrix can guide the behaviour of related cells to some degree. Studies have shown that the mechanical range of 1-7 kPa contributes to the differentiation of stem cells into endothelial cells and thus to the process of wound vascularization. Unfortunately, the regulatory mechanics of vascularizing wound coverings have been poorly studied. Silk fibroin (SF) has attracted much attention because of its good biocompatibility, degradability and adjustable mechanical properties. In this paper, silk scaffolds with mechanical properties of 2 kPa and 5.9 kPa were prepared by adjusting the mechanics of silk scaffolds in terms of freezing temperature and aligned structure. The mechanical properties of the 5.9 kPa aligned silk scaffold (ASS) showed good vascularization ability. By adjusting the intermediate conformation and physical structure of Silk fibroin (SF), the mechanical strength of the silk scaffold could be increased, enabling us to better understand the mechanical regulation mode. At the same time, the aligned structure of the aligned silk scaffold (ASS) promoted the migration and proliferation of cells related to wound repair to a certain extent. By adjusting the mechanical properties and physical structure of the material, an aligned silk scaffold with vascularization function was constructed, providing more possibilities for faster wound repair.

A mechanical, electrical dual autonomous self-healing multifunctional composite hydrogel

The versatile properties make hydrogels a potential multipurpose material that finds wide applications. However, the preparation of multipurpose hydrogels is very challenging. Here, we report a method based on free radical reaction and composite mechanisms to prepare mechanical and electrical self-healing multifunctional hydrogels. In this study, the introduction of imidazolium salt ionic liquids and glycerol in the hydrogel system endows the gels with good antibacterial, conductive, and adhesive properties and excellent antifreeze properties. The testing results show that the as-prepared hydrogel has stable mechanical and electrical properties even under the extremely cold condition of -50°C after self-healing. Moreover, the active esters formed in the dynamic radical reaction have better reducibility, thus further investing the as-prepared hydrogel with high antioxidant activity. The application results show that these comprehensive properties make such hydrogel system very useful in wound repair and wearable strain sensors.

Clinical Effectiveness of Dorsal Branch Skin Flap of Proper Palmar Digital Artery with Distal Pedicle in Repairing of Fingertip Soft Tissue Defect: A 1-Year Prospective Study in a Chinese Tertiary Referral Teaching Hospital

Background: Digital island flap remains among the most useful types of providing soft-tissues coverage for defect on the fingertip accompanied with underlying structures exposure. Nevertheless, its trends of functional and aesthetic issues such as the limited length of advancement and the limited flap size are the essential disadvantages. The main objective of the study was to assess the clinical effectiveness of dorsal branch skin flap of proper palmar digital artery with distal pedicle in repairing of fingertip soft tissue defect accompanied with underlying structures exposure. Methods: This is a 1-year prospective study, in which 21 patients (24 fingers) with traumatic fingertip skin and soft tissue defects had undergone emergency repair with dorsal skin flap of proper palmar digital artery with distal pedicle. The starting point of the dorsal proper palmar digital artery which is at the connection of distal interphalangeal joint with the digital midline was selected as the rotation point of the surgical skin flap, with an incision area of 1.1 cm × 1.4 cm-2.7 cm × 2.0 cm, the pedicle of 0.8-1.7 cm and disposition of 90°-120° to cover the fingertip. Results: All flaps had completely healed postoperatively. In 2 cases, tension blisters of the flap and partial necrosis were observed, which survived after change in dressing and rational administration vasodilator medication. Patients were followed up to 6 months. Favorable appearance and function were restored, and satisfactory recovery of the sensory functions of the fingers had been achieved. The two-point discrimination of skin flap with anastomosis of nerve could reach 4.5-9.4 mm (mean, 6.80 mm). Conclusions: Repairing the fingertip skin and soft tissue defect of 2^nd-5^th finger via primary surgical repair with dorsal distal pedicle or proper palmar digital artery skin flap is a good technique. The high survival rate of the flap, the favorable flap's appearance, and the satisfactory recovery of the sensory functions of the fingers are among the advantages of this reconstructive technique.

The promising pro-healing role of the association of mesoglycan and lactoferrin on skin lesions

Skin wound repair represents an important topic for the therapeutic challenges. Many molecules are commonly used as active principles of topical devices to induce the correct tissue regeneration. Among these molecules, mesoglycan, a mixture of glycosaminoglycans, and the lactoferrin have recently aroused interest. Here, for the first time, we used mesoglycan/lactoferrin to treat the cell populations mainly involved in wound healing. We showed that human keratinocytes, fibroblasts and endothelial cells migrate and invade more rapidly when treated with the association. Moreover, we found that mesoglycan/lactoferrin, are able to trigger the differentiation process of keratinocytes, the switch of the fibroblasts into myofibroblasts, the acquisition of a mesenchymal phenotype for the endothelial cells which, in this way, start to form the capillary-like structures. Additionally, we proved that the well known antimicrobial behavior of lactoferrin encourages the inhibition of S. aureus and P. aeruginosa biofilm formation by the whole association, providing an appealing feature for this formulation. Finally, by the in vivo analysis, we showed that the mesoglycan/lactoferrin favors the closure of skin wounds performed on the mice back. Beside the decrease of the lesion diameters, by a confocal analysis of mice biopsies we found that the use of the association strongly promote cell activation underlying the correct tissue regeneration. These results encourage to further investigation aiming the development of a new topical patch that includes this association.

An enzyme-responsive Gp1a-hydrogel for skin wound healing

Faster recovery and fewer scars are ideal wound healing. We have demonstrated that the cannabinoid receptor 2 (CB₂) agonist Gp1a is beneficial to skin wound healing, which inhibits inflammation and fibrogenesis while promoting re-epithelialization. However, the systemic administration is imprecise and overqualified for a local skin wound. Herein, we prepared Gp1a-gel using triglycerol monostearate (Tm) hydrogel and detected whether the Gp1a-gel worked effectively on mouse skin excision wounds. The results showed that Gp1a-gel might sustainably increase the CB₂ for at least 8 days. It decreased inflammation and fibrogenesis while promoting wound enclosure and re-epithelialization. These results suggested Gp1a-gel may utilize as a potential formulation strategy to treat the skin wound.

Proteomic analysis of Caenorhabditis elegans wound model reveals novel molecular players involved in repair

Wound repair is a multistep process which involves coordination of multiple molecular players from different cell types and pathways. Though the cellular processes that are taking place in order to repair damage is already known, molecular players involved in crucial pathways are still scarce. In this regard, the present study intends to uncover crucial players that are involved in the central repair events through proteomics approach which included 2-D GE and LC-MS/MS using Caenorhabditis elegans wound model. Initial gel-based 2-D GE and following protein-protein interaction (PPI) network analyses revealed active role of calcium signaling, acetylcholine transport and serotonergic neurotransmitter pathways. Further, gel-free LC-MS/MS and following PPI network analyses revealed the incidence of actin nucleation at the initial hours immediately after injury. Further by visualizing the PPI network and the interacting players, pink-1, a mitochondrial Serine/threonine-protein kinase which is known to regulate mitochondrial dynamics, was found to be the central player in facilitating the mitochondrial fission and its role was further verified using qPCR analysis and pink-1 transgenic worms. Overall, the study delivers new insights from crucial regulatory pathways and central players involved in wound repair using high throughput proteomic approaches and the mass spectrometry Data (PXD024629/PXD024744) are available via ProteomeXchange. SIGNIFICANCE.

Effect of the orientation of microskin on the survival rate of transplantation and improving the method

The direction of microskin transplantation is difficult to control, and the survival rate is critically affected. In this study, we show for the first time that survival rate of transplantation was improved by changing the direction of microskin. A human split-thickness skin graft was prepared as microskin (size of 1 mm × 1 mm), and was transplanted onto a wound in nude mice. The effect of the orientation of microskin on the survival rate of transplants was observed. The collagen membrane was first attached to the epidermal surface of pig skin, which was then cut into microskin and then they were floated on physiological saline. The effect of the collagen membrane on the orientation of microskin was observed. Then the microskin of pig with an epidermal surface attached to the collagen membrane was transplanted to the wound of the pig, and the survival rate of transplants was observed. In the 2^nd, 3^rd and 4^th week after transplantation of nude mice, the wound healing rate in group A (all of the microskin's epidermal surface was upward) was significantly higher than in other groups (P < 0.01). The floating rate and the forward floating rate in the experimental group were significantly higher than those in the control group (P < 0.01). Four weeks after microskin transplantation of pigs, the wound contraction rate in group A, compared with group B, was significantly lower, and the wound healing rate was significantly higher (P < 0.01). In microskin grafting, the direction of microskin significantly affects the survival rate of transplantation. The method of adhering the collagen membrane to the epidermal surface of microskin may ensure complete floating of microskin on the physiological saline with the epidermal surface facing up. This is a new method to improve the survival rate of microskin grafting.

The complexity of TGFβ/activin signaling in regeneration

The role of transforming growth factor β TGFβ/activin signaling in wound repair and regeneration is highly conserved in the animal kingdom. Various studies have shown that TGF-β/activin signaling can either promote or inhibit different aspects of the regeneration process (i.e., proliferation, differentiation, and re-epithelialization). It has been demonstrated in several biological systems that some of the different cellular responses promoted by TGFβ/activin signaling depend on the activation of Smad-dependent or Smad-independent signal transduction pathways. In the context of regeneration and wound healing, it has been shown that the type of R-Smad stimulated determines the different effects that can be obtained. However, neither the possible roles of Smad-independent pathways nor the interaction of the TGFβ/activin pathway with other complex signaling networks involved in the regenerative process has been studied extensively. Here, we review the important aspects concerning the TGFβ/activin signaling pathway in the regeneration process. We discuss data regarding the role of TGF-β/activin in the most common animal regenerative models to demonstrate how this signaling promotes or inhibits regeneration, depending on the cellular context.

A novel two-component, expandable bioadhesive for exposed defect coverage: Applicability to prenatal procedures

BACKGROUND/PURPOSE

We sought to test select properties of a novel, expandable bioadhesive composite that allows for enhanced adhesion control in liquid environments.

METHODS

Rabbit fetuses (n = 23) underwent surgical creation of spina bifida on gestational day 22-25 (term 32-33 days). Defects were immediately covered with a two-component tough adhesive consisting of a hydrogel made of a double network of ionically crosslinked alginate and covalently crosslinked polyacrylamide linked to a bridging chitosan polymer adhesive. Animals were euthanized prior to term for different analyses, including hydraulic pressure testing.

RESULTS

Hydrogels remained adherent in 70% (16/23) of the recovered fetuses and in all of the last 14 fetuses as the procedure was optimized. Adherent hydrogels showed a median two-fold (IQR: 1.7-2.4) increase in area at euthanasia, with defect coverage confirmed by ultrasound and histology. The median maximum pressure to repair failure was 15 mmHg (IQR: 7.8-55.3), exceeding reported neonatal cerebrospinal fluid pressures.

CONCLUSIONS

This novel bioadhesive composite allows for selective, stable attachment of an alginate-polyacrylamide hydrogel to specific areas of the spina bifida defect in a fetal rabbit model, while the hydrogel expands with the defect over time. It could become a valuable alternative for the prenatal repair of spina bifida and possibly other congenital anomalies.

TYPE OF STUDY

N/A (animal and laboratory study).

LEVEL OF EVIDENCE

N/A (animal and laboratory study).

Neutrophil signaling during myocardial infarction wound repair

Neutrophils are key effector cells of the innate immune system, serving as a first line of defense in the response to injury and playing essential roles in the wound healing process. Following myocardial infarction (MI), neutrophils infiltrate into the infarct region to propagate inflammation and begin the initial phase of cardiac wound repair. Pro-inflammatory neutrophils release proteases to degrade extracellular matrix (ECM), a necessary step for the removal of necrotic myocytes as a prelude for scar formation. Neutrophils transition their phenotype over time to regulate MI inflammation resolution and stabilize scar formation. Neutrophils contribute to the evolution from inflammation to resolution and scar formation by serving anti-inflammatory and repair functions. As anti-inflammatory cells, neutrophils contribute ECM proteins during scar formation, in particular fibronectin, galectin-3, and vimentin. The diverse and polarizing functions that contribute to MI wound repair make this innate immune cell a viable target to improve MI outcomes. Thus, understanding the signaling involved in neutrophil physiology in the context of MI may help to identify novel therapeutic targets.

Photobiomodulation invigorating collagen deposition, proliferating cell nuclear antigen and Ki67 expression during dermal wound repair in mice

The present investigation focuses on understanding the role of photobiomodulation in enhancing tissue proliferation. Circular excision wounds of diameter 1.5 cm were created on Swiss albino mice and treated immediately with 2 J/cm² and 10 J/cm² single exposures of the Helium-Neon laser along with sham-irradiated controls. During different days of healing progression (day 5, day 10, and day 15), the tissue samples upon euthanization of the animals were taken for assessing collagen deposition by Picrosirius red staining and cell proliferation (day 10) by proliferating cell nuclear antigen (PCNA) and Ki67. The positive influence of red light on collagen synthesis was found to be statistically significant on day 10 (P < 0.01) and day 15 (P < 0.05) post-wounding when compared to sham irradiation, as evident from the image analysis of collagen birefringence. Furthermore, a significant rise in PCNA (P < 0.01) and Ki67 (P < 0.05) expression was also recorded in animals exposed to 2 J/cm² when compared to sham irradiation and (P < 0.01) compared to the 10 J/cm² treated group as evidenced by the microscopy study. The findings of the current investigation have distinctly exhibited the assenting influence of red laser light on excisional wound healing in Swiss albino mice by augmenting cell proliferation and collagen deposition.

[Research advances on the roles of exosomes derived from vascular endothelial progenitor cells in wound repair]

Angiogenesis is the core step of wound repair, and vascular endothelial progenitor cells (EPC) play an extremely important role during wound repair. Recent studies have shown that vascular EPC-derived exosomes (EPC-Exo) can protect vessels, promote the proliferation and migration of vascular endothelial cells, and have anti-inflammatory, anti-oxidant and anti-apoptotic effects on vascular endothelial cells. This article reviews the mechanism of vascular EPC-Exo in angiogenesis and its potential applications in wound repair in recent years.

[National expert consensus on the application of natural dermal matrix in wound repair (2020 version)]

Natural dermal matrix has good biocompatibility and can serve as " biological template" in wound repair. According to the source of material, natural dermal matrix can be divided into acellular dermal matrix (ADM), denatured dermal matrix, and scar dermal matrix. ADM is a biological material prepared by removing cellular components from the skin and retaining extracellular matrix (ECM) of the dermis. ADM possesses abundant natural biological information, low immunogenicity, and excellent regenerative capacity, which has greatly promoted the development of wound healing specialty as dermal substitute. Denatured dermis matrix is a layer of dermal tissue made by superficial tangential excision or dermabrasion on deeply burned wounds. The retained denatured dermis can recover gradually after transplantation of autologous skin on its surface, with similar structure, morphology, and biomechanics to healthy dermis. Scar dermal matrix is a kind of dermal scaffold made of autologous split-thickness scar tissue, possessing the characteristics of high survival rate, good texture, and slight scar reaction. Scar dermal matrix can effectively reduce secondary damage to the donor site when repairing scar contracture deformity. Based on the research progress at home and abroad and the opinions of domestic experts, this paper summarizes the indications, application methods, contraindications, and considerations of different types of natural dermal matrix in application of wound repair.

Differences in sphere-forming cells from keratoconic and normal corneal tissue: Implications for keratoconus pathogenesis

Keratoconus is primarily an anterior corneal disorder of unclear aetiology. Stem cells may play a role in the perpetuation of keratoconus, although this has yet to be definitively established. Sphere-forming cells from normal human donor corneas have previously been shown to be a heterogenous mix of epithelial, stromal, stem and progenitor cell components which have potential for treatment of corneal dystrophies. Our work set out to isolate and characterise sphere-forming cells from human keratoconic tissue. Keratoconic donor corneas were successfully used to culture sphere-forming cells in vitro. Time lapse imaging of these spheres on a collagen surface over 8 days revealed keratoconic spheres lack the ability to maintain a central core and have diminished ability to repopulate the surface. Immunocytochemistry showed positive labelling for the stem cell marker 'Adenosine triphosphate-binding cassette sub-family B member 5 (ABCB5)' indicating stem cell retention and the myofibroblast marker alpha smooth muscle actin indicating wound repair while droplet digital Polymerase Chain Reaction confirmed an increase in expression of stem and stromal cell markers in keratoconic spheres compared to spheres cultured from normal donors at day 7 post-placement. Keratoconic sphere-forming cells showed a diminished repopulation ability, a faster wound healing response and lack of central core retention. These results suggest stem cells in keratoconus may be in an elevated state of wound repair and unable to respond appropriately to further injury in corneal maintenance. Sphere forming cell populations in keratoconus appear to be different to those isolated from normal corneas and this may be an important consideration in unearthing keratoconus aetiology.

Full- versus partial-thickness sutures: experimental models of corneal injury repair

PURPOSE

To evaluate the performance of full-thickness (FT) versus partial-thickness (PT) sutures in a full-thickness corneal wound in an animal model.

METHODS

This is a prospective, experimental, comparative, longitudinal study. A 6-mm linear, full-thickness corneal incision was performed on the right eye of eight domestic pigs. Eyes were randomly assigned for repair with interrupted PT (80-90% depth) sutures or FT 10-0 nylon sutures. Anterior segment OCT, corneal pachymetry and clinical photographs were obtained 1, 4 and 8 weeks postoperatively. Corneal thickness, depth of suture placement, perilesional edema, coaptation of wound edges and complications were noted. Histopathologic examination was performed at 8 weeks.

RESULTS

100% of the eyes with FT sutures developed a linear, less opaque scar. 100% of the eyes with PT developed a dense, opaque stromal scar (p = 0.02). Vascularization of the cornea was present in 75% of PT group and 25% in the FT group (p = 0.50). As the corneas healed, there was a marked trend toward thicker corneas in the PT group versus FT group with a median difference of - 63 µm at week 1 [median 788 µm vs. 725 µm, (p = 0.11)], - 38 µm at week 4, (724 µm vs. 686 µm, (p = 0.63)) and - 47 µm median difference at week 8 with (670 µm vs. 623 µm, (p = 0.06)). Histopathology showed disorganization of the collagen fibers and the formation of a retrocorneal fibrous membrane in the PT group.

CONCLUSIONS

The FT group presented less corneal edema at week 8 with a more linear and less opaque scar. Histopathology showed a better-organized scar and endothelialization without the formation of a fibrous membrane.

[Normative application of negative-pressure wound therapy to improve the wound repair level]

In recent 20 years, the technology of negative-pressure wound therapy (NPWT) has been widely used in the field of wound repair. Basic research and clinical application have proved that NPWT plays a positive role in regulating wound repair in many aspects. Compared with the previous 10 years, NPWT has made great progress in the last 10 years in negative pressure materials or equipment, as well as in the use method, mechanism research, and clinical application strategy. Strict and accurate grasp of the clinical application indication of NPWT and scientific application of NPWT to regulate the microenvironment of wound healing, effective improvement of the healing quality of different types of wounds, and further improve the level of wound repair are the core principles of the normative use of NPWT.

Long non-coding RNAs in cutaneous biology and keratinocyte carcinomas

Long non-coding RNAs (lncRNAs) are a largely uncharacterized group of non-coding RNAs with diverse regulatory roles in various biological processes. Recent observations have elucidated the functional roles of lncRNAs in cutaneous biology, e.g. in proliferation and differentiation of epidermal keratinocytes and in cutaneous wound repair. Furthermore, the role of lncRNAs in keratinocyte-derived skin cancers is emerging, especially in cutaneous squamous cell carcinoma (cSCC), which presents a significant burden to health care services worldwide and causes high mortality as metastatic disease. Elucidation of the functions of keratinocyte-specific lncRNAs will improve understanding of the molecular pathogenesis of epidermal disorders and skin cancers and can be exploited in development of new diagnostic and therapeutic applications for keratinocyte carcinomas. In this review, we summarize the current evidence of functionally important lncRNAs in cutaneous biology and in keratinocyte carcinomas.