Re-epithelialization of adult skin wounds: Cellular mechanisms and therapeutic strategies

Sirtuin-6 knockout causes exacerbated stalled healing of diabetic ulcers in mice

BACKGROUND

Diabetic ulcers (DUs) are characterized by chronic inflammation and delayed re-epithelialization, with a high incidence and weighty economic burden. The primary therapeutic strategies for refractory wounds include surgery, non-invasive wound therapy, and drugs, while the optimum regimen remains controversial. Sirtuin-6 (SIRT6) is a histone deacetylase and a key epigenetic factor that exerts anti-inflammatory and pro-proliferatory effects in wound healing. However, the exact function of SIRT6 in DUs remains unclear.

METHODS

We generated tamoxifen-inducible SIRT6 knockout mice by crossing SIRT6flox/flox homozygous mice with UBC-creERT2+ transgenic mice. Systemic SIRT6 null mice, under either normal or diabetic conditions, were utilized to assess the effects of SIRT6 in DUs treatment. Gene and protein expressions of SIRT6 and inflammatory cytokines were measured by Western blotting and RT-qPCR. Histopathological examination confirmed the altered re-epithelialization (PCNA), inflammation (NF-κB p50 and F4/80), and angiogenesis (CD31) markers during DUs restoration.

RESULTS

Knockout of SIRT6 inhibited the healing ability of DUs, presenting attenuated re-epithelialization (PCNA), exacerbated inflammation responses (NF-κB p50, F4/80, Il-1β, Tnf-α, Il-6, Il-10, and Il-4), and hyperplasia vascular (CD31) compared with control mice.

CONCLUSIONS

SIRT6 could boost impaired wound healing through improving epidermal proliferation, inflammation, and angiogenesis. Our study highlighted the therapeutic potential of the SIRT6 agonist for DUs treatment.

3D Porous Polymer Scaffold-Conjugated KGF-Mimetic Peptide Promotes Functional Skin Regeneration in Chronic Diabetic Wounds

The re-epithelialization process gets severely dysregulated in chronic nonhealing diabetic foot ulcers/wounds. Keratinocyte growth factor (KGF or FGF-7) is the major modulator of the re-epithelialization process, which regulates the physiological phenotypes of cutaneous keratinocytes. The existing therapeutic strategies of growth factor administration have several limitations. To overcome these, we have designed a KGF-mimetic peptide (KGFp, 13mer) based on the receptor interaction sites in murine KGF. KGFp enhanced migration and transdifferentiation of mouse bone marrow-derived MSCs toward keratinocyte-like cells (KLCs). A significant increase in the expression of skin-specific markers Bnc1 (28.5-fold), Ck5 (14.6-fold), Ck14 (26.1-fold), Ck10 (187.7-fold), and epithelial markers EpCam (23.3-fold) and Cdh1 (64.2-fold) was associated with the activation of ERK1/2 and STAT3 molecular signaling in the KLCs. Further, to enhance the stability of KGFp in the wound microenvironment, it was conjugated to biocompatible 3D porous polymer scaffolds without compromising its active binding sites followed by chemical characterization using Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, dynamic mechanical analysis, and thermogravimetry. In vitro evaluation of the KGFp-conjugated 3D polymer scaffolds revealed its potential for transdifferentiation of MSCs into KLCs. Transplantation of allogeneic MSCGFP using KGFp-conjugated 3D polymer scaffolds in chronic nonhealing type 2 diabetic wounds (db/db transgenic, 50-52 weeks old male mice) significantly enhanced re-epithelialization-mediated wound closure rate (79.3%) as compared to the control groups (Untransplanted -22.4%, MSCGFP-3D polymer scaffold -38.5%). Thus, KGFp-conjugated 3D porous polymer scaffolds drive the fate of the MSCs toward keratinocytes that may serve as potential stem cell delivery platform technology for tissue engineering and transplantation.

Injectable nanoparticle-crosslinked xyloglucan/ε-poly-l-lysine composite hydrogel with hemostatic, antimicrobial, and angiogenic properties for infected wound healing

Skin wounds are susceptible to infection, leading to severe inflammatory reactions that can progress to chronic wounds, ultimately causing significant physical and mental distress to the patient. In this study, we propose an injectable composite hydrogel achieved through one-pot gelation of oxidized xyloglucan (OXG), cationic polyamide ε-poly-l-lysine (EPL), and surface amino-rich silicon nanoparticles (SiNPs). OXG exhibits commendable anti-inflammatory properties and provides crosslinking sites. SiNPs serve as mechanically reinforced crosslinkers, facilitating the construction of a dynamic Schiff base network. SiNPs significantly reduced the gelation time to 3 s and tripled the storage modulus of the hydrogels. Additionally, the combination of EPL and SiNPs demonstrated synergistic antimicrobial activity against both S. aureus and E. coli. Notably, the hydrogel effectively halted liver bleeding within 30 s. The hydrogel demonstrated outstanding shear-thinning and self-healing properties, crucial considerations for the design of injectable hydrogels. Furthermore, its efficacy was evaluated as a wound dressing in a mouse model with S. aureus infection. The results indicated that, compared to commercial products, the hydrogel exhibited a shorter wound healing time, decreased inflammation, thinner epithelium, increased hair follicles, enhanced neovascularization, and more substantial collagen deposition. These findings strongly suggest the promising potential of the proposed hydrogel as an effective wound dressing for the treatment of infected wounds.

Hydrogel Loaded with Extracellular Vesicles: An Emerging Strategy for Wound Healing

An increasing number of novel biomaterials have been applied in wound healing therapy. Creating beneficial environments and containing various bioactive molecules, hydrogel- and extracellular vesicle (EV)-based therapies have respectively emerged as effective approaches for wound healing. Moreover, the synergistic combination of these two components demonstrates more favorable outcomes in both chronic and acute wound healing. This review provides a comprehensive discussion and summary of the combined application of EVs and hydrogels to address the intricate scenario of wounds. The wound healing process and related biological mechanisms are outlined in the first section. Subsequently, the utilization of EV-loaded hydrogels during the wound healing process is evaluated and discussed. The moist environment created by hydrogels is conducive to wound tissue regeneration. Additionally, the continuous and controlled release of EVs from various origins could be achieved by hydrogel encapsulation. Finally, recent in vitro and in vivo studies reported on hydrogel dressings loaded with EVs are summarized and challenges and opportunities for the future clinical application of this therapeutic approach are outlined.

Exosome/antimicrobial peptide laden hydrogel wound dressings promote scarless wound healing through miR-21-5p-mediated multiple functions

Mesenchymal stem cell (MSC)-based therapy is an effective strategy for regenerative therapy. However, safety and ease of use are still issues to be overcome in clinical applications. Exosomes are naturally derived nanoparticles containing bioactive molecules, which serve as ideal cell-free therapeutic modalities. However, issues such as delivery, long-term preservation and activity maintenance of exosomes are other problems that limit their application. In this study, we proposed the use of rapid freeze-dry-thaw macroporous hydrogels for the encapsulation of HucMSC-derived exosomes (HucMSC-Exos) combined with an antimicrobial peptide coating. This exosome-encapsulated hyaluronic acid macroporous hydrogel HD-DP7/Exo can achieve long-term storage and transport by lyophilization and can be rapidly redissolved for treatment. After comprehensively comparing the therapeutic effects of HucMSC-Exos and HucMSC-loaded hydrogels, we found that HucMSC-Exos could also effectively regulate fibroblasts, vascular endothelial cells, and macrophages and inhibit myofibroblast-mediated fibrosis, thus promoting tissue regeneration and inhibiting scar formation in a mouse model of deep second-degree burn infection healing. These properties of lyophilized storage and whole-process-repair make HD-DP7/Exo have potential application value and application prospects.

Nanomaterial strategies in wound healing: A comprehensive review of nanoparticles, nanofibres and nanosheets

Wound healing is a complex process that orchestrates the coordinated action of various cells, cytokines and growth factors. Nanotechnology offers exciting new possibilities for enhancing the healing process by providing novel materials and approaches to deliver bioactive molecules to the wound site. This article elucidates recent advancements in utilizing nanoparticles, nanofibres and nanosheets for wound healing. It comprehensively discusses the advantages and limitations of each of these materials, as well as their potential applications in various types of wounds. Each of these materials, despite sharing common properties, can exhibit distinct practical characteristics that render them particularly valuable for healing various types of wounds. In this review, our primary focus is to provide a comprehensive overview of the current state-of-the-art in applying nanoparticles, nanofibres, nanosheets and their combinations to wound healing, serving as a valuable resource to guide researchers in their appropriate utilization of these nanomaterials in wound-healing research. Further studies are necessary to gain insight into the application of this type of nanomaterials in clinical settings.

General Semi-Solid Freeze Casting for Uniform Large-Scale Isotropic Porous Scaffolds: An Application for Extensive Oral Mucosal Reconstruction

Ice-templated porous biomaterials possess transformative potential in regenerative medicine; yet, scaling up ice-templating processes for broader applications-owing to inconsistent pore formation-remains challenging. This study reports an innovative semi-solid freeze-casting technique that draws inspiration from semi-solid metal processing (SSMP) combined with ice cream-production routines. This versatile approach allows for the large-scale assembly of various materials, from polymers to inorganic particles, into isotropic 3D scaffolds featuring uniformly equiaxed pores throughout the centimeter scale. Through (cryo-)electron microscopy, X-ray tomography, and finite element modeling, the structural evolution of ice grains/pores is elucidated, demonstrating how the method increases the initial ice nucleus density by pre-fabricating a semi-frozen slurry, which facilitates a transition from columnar to equiaxed grain structures. For a practical demonstration, as-prepared scaffolds are integrated into a bilayer tissue patch using biodegradable waterborne polyurethane (WPU) for large-scale oral mucosal reconstruction in minipigs. Systematic analyses, including histology and RNA sequencing, prove that the patch modulates the healing process toward near-scarless mucosal remodeling via innate and adaptive immunomodulation and activation of pro-healing genes converging on matrix synthesis and epithelialization. This study not only advances the field of ice-templating fabrication but sets a promising precedent for scaffold-based large-scale tissue regeneration.

Modulation of gene expression in skin wound healing by photobiomodulation therapy: A systematic review in vivo studies

BACKGROUND

Wound healing is a multistep process involving coordinated responses of a variety of cell types, cytokines, growth factors, and extracellular matrix (ECM) components leading to the physiological restoration of tissue integrity. Photobiomodulation therapy (PBMT) has been highlighted as an approach to improve the healing process, nonetheless at the molecular level, the effects of PBMT are not entirely understood.

AIM

To systematically review publications that investigated gene expression after PBMT during in vivo skin repair.

METHODS

An electronic search was undertaken in Medline Ovid (Wolters Kluwer), PubMed (National Library of Medicine), Web of Science (Thomson Reuters), Scopus (Elsevier), Embase, and LILACS databases. The search strategy was conducted from the terms: low-level light therapy, gene expression, and wound healing and their synonyms. The databases were consulted in December 2023 and no publication year limit was used.

RESULTS

Eleven studies were included in this review and the expression of 186 genes was evaluated. PBMT modified the expression of several targets genes studied, such as down-regulation of genes related to extracellular matrix proteases (MMP2 and MMP9) and pro-inflammatory cytokines (IL10 and IL6) and up-regulation of DNMT3A and BFGF.

CONCLUSION

This review demonstrates that PBMT is capable of regulating gene expression during wound healing. Most evidence showed a positive impact of PBMT in regulating genes linked to inflammatory cytokines improving skin wound healing. Yet, the effects of PBMT in genes involved in other mechanisms still need to be better understood.

Phenylboronic acid functionalized dextran loading curcumin as nano-therapeutics for promoting the bacteria-infected diabetic wound healing

Chronic bacterial infections, excessive inflammation, and oxidative stress significantly hinder diabetic wound healing by prolonging the inflammatory phase and complicating the healing process. In this study, phenylboronic acid functionalized dextran (PODP) was developed to encapsulate curcumin, referred to as PODP@Cur. Experimental results indicate that PODP significantly improves the water solubility of curcumin and exhibits synergistic biological activity both in vitro and in vivo. PODP@Cur is capable of accelerating drug release under the pathological microenvironment with ROS accumulation. Furthermore, phenylboronic acid (PBA) has demonstrated potential for targeted bacterial drug delivery, enhancing antibacterial efficacy and trapping free LPS/PGN from dead bacteria to reduce undesirable inflammation. In a diabetic mouse model, PODP@Cur exhibits an excellent antibacterial, anti-inflammatory and antioxidant activities to ultimately promote the efficient and safe wound healing. Due to the specific interaction between PBA and LPS, PODP@Cur could enhance antibacterial activity against bacteria, reduce toxic side effects on normal cells, and alleviate the LPS-mediated pro-inflammatory pathological microenvironment. Therefore, PODP@Cur is capable of being exploited as an efficient and safe candidate for promoting the bacteria-infected diabetic wound healing.

Alcaligenes faecalis corrects aberrant matrix metalloproteinase expression to promote reepithelialization of diabetic wounds

Chronic wounds are a common and costly complication of diabetes, where multifactorial defects contribute to dysregulated skin repair, inflammation, tissue damage, and infection. We previously showed that aspects of the diabetic foot ulcer microbiota were correlated with poor healing outcomes, but many microbial species recovered remain uninvestigated with respect to wound healing. Here, we focused on Alcaligenes faecalis, a Gram-negative bacterium that is frequently recovered from chronic wounds but rarely causes infection. Treatment of diabetic wounds with A. faecalis accelerated healing during early stages. We investigated the underlying mechanisms and found that A. faecalis treatment promotes reepithelialization of diabetic keratinocytes, a process that is necessary for healing but deficient in chronic wounds. Overexpression of matrix metalloproteinases in diabetes contributes to failed epithelialization, and we found that A. faecalis treatment balances this overexpression to allow proper healing. This work uncovers a mechanism of bacterial-driven wound repair and provides a foundation for the development of microbiota-based wound interventions.

Latest Insights into the In Vivo Studies in Murine Regarding the Role of TRP Channels in Wound Healing-A Review

Wound healing involves physical, chemical and immunological processes. Transient receptor potential (TRP) and other ion channels are implicated in epidermal re-epithelization. Ion movement across ion channels can induce transmembrane potential that leads to transepithelial potential (TEP) changes. TEP is present in epidermis surrounding the lesion decreases and induces an endogenous direct current generating an epithelial electric field (EF) that could be implicated in wound re-epithelialization. TRP channels are involved in the activation of immune cells during mainly the inflammatory phase of wound healing. The aim of the study was to review the mechanisms of ion channel involvement in wound healing in in vivo experiments in murine (mice, rats) and how can this process be influenced. This review used the latest results published in scientific journals over the last year and this year to date (1 January 2023-31 December 3000) in order to include the in-press articles. Some types of TRP channels, such as TRPV1, TRPV3 and TRPA1, are expressed in immune cells and can be activated by inflammatory mediators. The most beneficial effects in wound healing are produced using agonists of TRPV1, TRPV4 and TRPA1 channels or by inhibiting with antagonists, antisense oligonucleotides or knocking down TRPV3 and TRPM8 channels.

Electrospun Nanofiber Scaffold for Skin Tissue Engineering: A Review

Skin tissue engineering (STE) is widely regarded as an effective approach for skin regeneration. Several synthetic biomaterials utilized for STE have demonstrated favorable fibrillar characteristics, facilitating the regeneration of skin tissue at the site of injury, yet they have exhibited a lack of in situ degradation. Various types of skin regenerative materials, such as hydrogels, nanofiber scaffolds, and 3D-printing composite scaffolds, have recently emerged for use in STE. Electrospun nanofiber scaffolds possess distinct advantages, such as their wide availability, similarity to natural structures, and notable tissue regenerative capabilities, which have garnered the attention of researchers. Hence, electrospun nanofiber scaffolds may serve as innovative biological materials possessing the necessary characteristics and potential for use in tissue engineering. Recent research has demonstrated the potential of electrospun nanofiber scaffolds to facilitate regeneration of skin tissues. Nevertheless, there is a need to enhance the rapid degradation and limited mechanical properties of electrospun nanofiber scaffolds in order to strengthen their effectiveness in soft tissue engineering applications in clinical settings. This Review centers on advanced research into electrospun nanofiber scaffolds, encompassing preparation methods, materials, fundamental research, and preclinical applications in the field of science, technology, and engineering. The existing challenges and prospects of electrospun nanofiber scaffolds in STE are also addressed.

MoO3-X nanodots coated suture for combating surgical site infection via antibacterial and anti-inflammatory properties

Surgical site infection (SSI) significantly affects patient recovery time, health outcomes and quality of life which is closely associated with the use of implants or mesh. Sutures are the most frequently used implants that play a significant role in the development of SSI. Studies have demonstrated that the administration of effective bactericidal and anti-inflammatory treatments can significantly decrease the incidence of SSI. To address this concern, a versatile suture was engineered by coating MoO3-X nanodots in this study. The incorporation of MoO3-X nanodots endowed the suture with desirable antibacterial and anti-inflammatory properties that were evaluated in in vitro and in vivo experiments. The results showed its remarkable ability to facilitate wound healing and prevent SSI through its dual action of combating bacterial infection and reducing inflammation. These findings highlight the promising potential of this multifunctional surgical suture as a versatile tool to promote better outcomes in surgical procedures.

Silk Fibroin and Its Nanocomposites for Wound Care: A Comprehensive Review

For most individuals, wound healing is a highly organized, straightforward process, wherein the body transitions through different phases in a timely manner. However, there are instances where external intervention becomes necessary to support and facilitate different phases of the body's innate healing mechanism. Furthermore, in developing countries, the cost of the intervention significantly impacts access to treatment options as affordability becomes a determining factor. This is particularly true in cases of long-term wound treatment and management, such as chronic wounds and infections. Silk fibroin (SF) and its nanocomposites have emerged as promising biomaterials with potent wound-healing activity. Driven by this motivation, this Review presents a critical overview of the recent advancements in different aspects of wound care using SF and SF-based nanocomposites. In this context, we explore various formats of hemostats and assess their suitability for different bleeding situations. The subsequent sections discuss the primary causes of nonhealing wounds, i.e., prolonged inflammation and infections. Herein, different treatment strategies to achieve immunomodulatory and antibacterial properties in a wound dressing were reviewed. Despite exhibiting excellent pro-healing properties, few silk-based products reach the market. This Review concludes by highlighting the bottlenecks in translating silk-based products into the market and the prospects for the future.

Preparation of Luvangetin Nanoemulsions: Antimicrobial Mechanism and Role in Infected Wound Healing

Purpose

Incorporation of luvangetin in nanoemulsions for antimicrobial and therapeutic use in infected wound healing.

Patients and Methods

Luvangetin nanoemulsions were prepared by high-speed shear method and characterized based on their appearance structure, average droplet size, polydispersity index (PDI), electric potential, storage stability. Optimized formulation of luvangetin nanoemulsion by Box-Behnken design (BBD). The antimicrobial activity and antimicrobial mechanism of luvangetin nanoemulsions against common hospital pathogens, ie, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), were investigated using luvangetin nanoemulsions. The biosafety of luvangetin nanoemulsion was evaluated through cytotoxicity, apoptosis, and reactive oxygen species (ROS) assay experiments using human normal epidermal cells and endothelial cells. Finally, the effect of luvangetin nanoemulsion on healing of infected wounds was investigated in B6 mice.

Results

Luvangetin nanoemulsion formulation consists of 2.5% sunflower seed oil, 10% emulsifier Span-20 and 7 minutes of shear time, and with good stability. Luvangetin nanoemulsion produces antibacterial activity against S. aureus and E. coli by disrupting the structure of bacterial cell membranes. Luvangetin nanoemulsion are biologically safe for HaCat and HUVEC. Luvangetin nanoemulsion showed good therapeutic effect on MRSA infected wounds in mice.

Conclusion

For the first time, developed a new formulation called luvangetin nanoemulsion, which exhibited superior antibacterial effects against Gram-positive bacteria. Luvangetin nanoemulsion has a favorable effect in promoting infected wound healing. We have combined luvangetin, which has multiple activities, with nanoemulsions to provide a new topical fungicidal formulation, and have comprehensively evaluated its effectiveness and safety, opening up new possibilities for further applications of luvangetin.

AT2R Activation Improves Wound Healing in a Preclinical Mouse Model

Abnormal skin healing resulting in chronic wounds or hypertrophic scarring remains a major healthcare burden. Here, the antifibrotic angiotensin II type 2 receptor (AT2R) signaling pathway was modulated to determine its impact on cutaneous wound healing. Balb/c mice received two splinted full-thickness wounds. Topical treatments with the selective AT2R agonist compound 21 (C21) and/or selective antagonist PD123319 or saline vehicle were administered until sacrifice on post-wounding days 7 or 10. The rate of wound re-epithelialization was accelerated by PD123319 and combination treatments. In vitro, C21 significantly reduced human fibroblast migration. C21 increased both collagen and vascular densities at days 7 and 10 post-wounding and collagen I:III ratio at day 10, while PD123319 and combination treatments decreased them. Genes associated with regeneration and repair were upregulated by C21, while PD123319 treatment increased the expression of genes associated with inflammation and immune cell chemotaxis. C21 treatment reduced wound total leukocyte and neutrophil staining densities, while PD123319 increased these and macrophage densities. Overall, AT2R activation with C21 yields wounds that mature more quickly with structural, cellular, and gene expression profiles more closely approximating unwounded skin. These findings support AT2R signal modulation as a potential therapeutic target to improve skin quality during wound healing.

Electrospun Nanofibrous Biocomposite of Royal Jelly/Chitosan/Polyvinyl Alcohol (RJ/CS/PVA) Gel as a Biological Dressing for P. aeruginosa-Infected Burn Wound

Burn wounds are vulnerable to various infections due to damage to the tissue and changes in immune responses. Pseudomonas aeruginosa is a critical bacterium that can cause burn wound infections, which can be life-threatening and delay wound healing. Therefore, it is essential to develop an efficient strategy to prevent the spread of infection in burn wounds. The present study aims to investigate the effectiveness of electrospun nanofibers of royal jelly on a chitosan/polyvinyl alcohol polymer scaffold in repairing burn wounds infected with Pseudomonas aeruginosa. To achieve this, the researchers analyzed the morphology and physicochemical properties of the synthesized nanofibers using SEM, FTIR, BET, and TGA analyses. They also examined the antibacterial properties of the nanofibers using agar diffusion and spread plate techniques. In addition, hemolysis tests were carried out to assess biocompatibility. Finally, the ability of the nanofibers to repair burn wounds infected with Pseudomonas aeruginosa was evaluated using a laboratory mouse model. The study results showed that the synthesized nanofibers had desirable morphology and physicochemical properties and significant antibacterial effects in both in vitro and in vivo conditions. Also, loading RJ into the polymer scaffold significantly reduced erythrocyte lysis. The wound healing and contraction rates were significantly higher than the control groups, and tissue repair, re-epithelialization, and collagen synthesis occurred faster, preventing the spread of infection to deeper tissue areas. Based on these findings, the synthesized system has the potential to serve as a suitable substitute for some invasive treatments and chemical drugs to improve chronic wounds and manage infection control in burn injuries.

Multifunctional polyvinyl alcohol/poly-dopamine hydrogels loaded with bio-nano composites promote wound healing by repairing endogenous electric fields

In this paper, a heart-shaped nanocomposite (MXenen@Cu-MOF, MC) has been prepared by hydrothermal method. This material can effectively prevent the accumulation of MXene, improve the material's electrical conductivity and antibacterial properties. In addition, it is loaded into Polyvinyl alcohol/Poly-dopamine hydrogel wound dressings (PPMC), which can effectively destroy bacterial biofilms and provide a new pathway for internal electrical currents, helping to repair internal electric fields and promote wound healing. Through the concentration gradient experiments of hydrogel such as antibacterial, conductive, hemolysis and cell migration, we believe that the addition of MC can improve the basic properties of hydrogel. Among them, PPMC0.2 is the hydrogel with the best performance under the premise of meeting bio-compatibility. Its resistance, between 500 and 1000 Ω, is lower than the skin resistance at the wound site and provides the basis for the passage of current through the body. In addition, the cell mobility (24h) of PPMC0.2 reached 58%, and the wound healing rate (6day) was 81.84%, which was much higher than that of other experimental groups. The experimental results proved that PPMC hydrogel can promote wound healing, and this study also provided a new therapeutic idea for chronic wound healing.

Cupric-polymeric nanoreactors integrate into copper metabolism to promote chronic diabetic wounds healing

Given multifunction of copper (Cu) contributing to all stages of the physiology of wound healing, Cu-based compounds have great therapeutic potentials to accelerate the wound healing, but they must be limited to a very low concentration range to avoid detrimental accumulation. Additionally, the cellular mechanism of Cu-based compounds participating the healing process remains elusive. In this study, copper oxide nanoparticles (CuONPs) were synthesized to mimic the multiple natural enzymes and trapped into PEG-b-PCL polymersomes (PS) to construct cupric-polymeric nanoreactors (CuO@PS) via a direct hydration method, thus allowing to compartmentalize Cu-based catalytic reactions in an isolated space to improve the efficiency, selectivity, recyclability as well as biocompatibility. While nanoreactors trafficked to lysosomes following endocytosis, the released Cu-based compounds in lysosomal lumen drove a cytosolic Cu+ influx to mobilize Cu metabolism mostly via Atox1-ATP7a/b-Lox axis, thereby activating the phosphorylation of mitogen-activated protein kinase 1 and 2 (MEK1/2) to initiate downstream signaling events associated with cell proliferation, migration and angiogenesis. Moreover, to facilitate to lay on wounds, cupric-polymeric nanoreactors were finely dispersed into a thermosensitive Pluronic F127 hydrogel to form a composite hydrogel sheet that promoted the healing of chronic wounds in diabetic rat models. Hence, cupric-polymeric nanoreactors represented an attractive translational strategy to harness cellular Cu metabolism for chronic wounds healing.

Efficacy and safety of radiofrequency in the treatment of hidradenitis suppurativa; a systematic review

BACKGROUND AND AIMS

Hidradenitis suppurativa (HS) is an inflammatory skin disease affecting apocrine gland-bearing sites of the body. Radiofrequency (RF) is a minimally invasive method that acts by minimizing thermal damage to the dermis, resulting in collagen synthesis and scar improvement. We systematically reviewed the efficacy and safety of RF in treating HS.

METHODS

A systematic search was performed up to November 18th, 2023, in PubMed/Medline, Ovid Embase, and Web of Science. Clinical studies with English full texts were included. The National Institute of Health (NIH) Quality Assessment Tool for clinical trials and Methodological quality and synthesis of case series and case reports by Murad et al. were utilized for critical appraisal.

RESULTS

Out of 55 identified studies, 11 met our inclusion criteria with 167 subjects who underwent RF therapy alone or combined with an intense pulsed laser (IPL), known as LAight®. LAight® significantly improved clinical outcomes in mild-to-moderate HS patients based on the Dermatology Life Quality Index (DLQI), International Hidradenitis Suppurativa Score System (IHS4), Pain-Numerical Rating Scale (NRS), and Hidradenitis Suppurativa Clinical Response (HiSCR). Moreover, RF therapy alone significantly alleviated the clinical manifestations in patients with mild-to-moderate HS. Additionally, fractional microneedling RF significantly decreased HS-associated inflammatory markers. RF was found to be safe with limited adverse events. However, in moderate-to-severe HS, RF has failed to yield satisfactory results.

CONCLUSION

RF is a safe energy-based method with promising outcomes, especially for long-term application in mild-to-moderate HS. In moderate-to-severe cases, RF should be combined with a systemic medication for further beneficial impacts.

Immediate but Temporal Response: The Role of Distal Epithelial Cells in Wound Healing

Efficient oral mucosal wound healing requires coordinated responses from epithelial progenitor cells, yet their spatiotemporal recruitment and activation remain unclear. Using a mouse model of palatal mucosal wound healing, we investigated the dynamics of epithelial cells during this process. Proliferation analysis revealed that, in addition to the expected proliferation center near the wound edge, distal cell populations rapidly activated post-injury by elevating their mitotic activity. These distal cells displayed predominant lateral expansion in the basal layer, suggesting roles beyond just tissue renewal. However, while proximal proliferation center cells sustained heightened proliferation until re-epithelialization was completed, distal cells restored basal turnover rates before wound closure, indicating temporally confined contributions. Lineage tracing of Wnt-responsive epithelial cells showed remarkable clone expansion in basal layers both proximally and distally after wounding, contrasting with gradual clone expansion in homeostasis. Although prioritizing tissue repair, epithelial progenitor cells maintained differentiation programs and barrier functions, with the exception of the leading edge. At the leading edge, we found accelerated cell turnover, but the differentiation program was suspended. In summary, our findings uncovered that oral wound re-epithelialization involves two phases: an initial widespread response with proliferation of proximal and distal cells, followed by proliferation confined to the wound proximal region. Uncovering these stage-specific healing mechanisms provides insights for developing targeted therapeutic strategies to improve wound care.

Floating electrode-dielectric barrier discharge-based plasma promotes skin regeneration in a full-thickness skin defect mouse model

Wound healing involves a complex and dynamic interplay among various cell types, cytokines, and growth factors. Macrophages and transforming growth factor-β1 (TGF-β1) play an essential role in different phases of wound healing. Cold atmospheric plasma has a wide range of applications in the treatment of chronic wounds. Hence, we aimed to investigate the safety and efficacy of a custom-made plasma device in a full-thickness skin defect mouse model. Here, we investigated the wound tissue on days 6 and 12 using histology, qPCR, and western blotting. During the inflammation phase of wound repair, macrophages play an important role in the onset and resolution of inflammation, showing decreased F4/80 on day 6 of plasma treatment and increased TGF-β1 levels. The plasma-treated group showed better epidermal epithelialization, dermal fibrosis, collagen maturation, and reduced inflammation than the control group. Our findings revealed that floating electrode-dielectric barrier discharge (FE-DBD)-based atmospheric-pressure plasma promoted significantly faster wound healing in the plasma-treated group than that in the control group with untreated wounds. Hence, plasma treatment accelerated wound healing processes without noticeable side effects and suppressed pro-inflammatory genes, suggesting that FE-DBD-based plasma could be a potential therapeutic option for treating various wounds.

Critical Role of CD55 in Controlling Wound Healing

How reparative processes are coordinated following injury is incompletely understood. In recent studies, we showed that autocrine C3a and C5a receptor (C3ar1 and C5ar1) G protein-coupled receptor signaling plays an obligate role in vascular endothelial growth factor receptor 2 growth signaling in vascular endothelial cells. We documented the same interconnection for platelet-derived growth factor receptor growth signaling in smooth muscle cells, epidermal growth factor receptor growth signaling in epidermal cells, and fibroblast growth factor receptor signaling in fibroblasts, indicative of a generalized cell growth regulatory mechanism. In this study, we examined one physiological consequence of this signaling circuit. We found that disabling CD55 (also known as decay accelerating factor), which lifts restraint on autocrine C3ar1/C5ar1 signaling, concomitantly augments the growth of each cell type. The mechanism is heightened C3ar1/C5ar1 signaling resulting from the loss of CD55's restraint jointly potentiating growth factor production by each cell type. Examination of the effect of lifted CD55 restraint in four types of injury (burn, corneal denudation, ear lobe puncture, and reengraftment of autologous skin) showed that disabled CD55 function robustly accelerated healing in all cases, whereas disabled C3ar1/C5ar1 signaling universally retarded it. In wild-type mice with burns or injured corneas, applying a mouse anti-mouse CD55 blocking Ab (against CD55's active site) to wounds accelerated the healing rate by 40-70%. To our knowledge, these results provide new insights into mechanisms that underlie wound repair and open up a new tool for accelerating healing.

Molecular characterization of chronic cutaneous wounds reveals subregion- and wound type-specific differential gene expression

A limited understanding of the pathology underlying chronic wounds has hindered the development of effective diagnostic markers and pharmaceutical interventions. This study aimed to elucidate the molecular composition of various common chronic ulcer types to facilitate drug discovery strategies. We conducted a comprehensive analysis of leg ulcers (LUs), encompassing venous and arterial ulcers, foot ulcers (FUs), pressure ulcers (PUs), and compared them with surgical wound healing complications (WHCs). To explore the pathophysiological mechanisms and identify similarities or differences within wounds, we dissected wounds into distinct subregions, including the wound bed, border, and peri-wound areas, and compared them against intact skin. By correlating histopathology, RNA sequencing (RNA-Seq), and immunohistochemistry (IHC), we identified unique genes, pathways, and cell type abundance patterns in each wound type and subregion. These correlations aim to aid clinicians in selecting targeted treatment options and informing the design of future preclinical and clinical studies in wound healing. Notably, specific genes, such as PITX1 and UPP1, exhibited exclusive upregulation in LUs and FUs, potentially offering significant benefits to specialists in limb preservation and clinical treatment decisions. In contrast, comparisons between different wound subregions, regardless of wound type, revealed distinct expression profiles. The pleiotropic chemokine-like ligand GPR15L (C10orf99) and transmembrane serine proteases TMPRSS11A/D were significantly upregulated in wound border subregions. Interestingly, WHCs exhibited a nearly identical transcriptome to PUs, indicating clinical relevance. Histological examination revealed blood vessel occlusions with impaired angiogenesis in chronic wounds, alongside elevated expression of genes and immunoreactive markers related to blood vessel and lymphatic epithelial cells in wound bed subregions. Additionally, inflammatory and epithelial markers indicated heightened inflammatory responses in wound bed and border subregions and reduced wound bed epithelialization. In summary, chronic wounds from diverse anatomical sites share common aspects of wound pathophysiology but also exhibit distinct molecular differences. These unique molecular characteristics present promising opportunities for drug discovery and treatment, particularly for patients suffering from chronic wounds. The identified diagnostic markers hold the potential to enhance preclinical and clinical trials in the field of wound healing.

Platelet rich fibrin and simvastatin-loaded pectin-based 3D printed-electrospun bilayer scaffold for skin tissue regeneration

Designing multifunctional wound dressings is a prerequisite to prevent infection and stimulate healing. In this study, a bilayer scaffold (BS) with a top layer (TL) comprising 3D printed pectin/polyacrylic acid/platelet rich fibrin hydrogel (Pec/PAA/PRF) and a bottom nanofibrous layer (NL) containing Pec/PAA/simvastatin (SIM) was produced. The biodegradable and biocompatible polymers Pec and PAA were cross-linked to form hydrogels via Ca2+ activation through galacturonate linkage and chelation, respectively. PRF as an autologous growth factor (GF) source and SIM together augmented angiogenesis and neovascularization. Because of 3D printing, the BS possessed a uniform distribution of PRF in TL and an average fiber diameter of 96.71 ± 18.14 nm was obtained in NL. The Young's modulus of BS was recorded as 6.02 ± 0.31 MPa and its elongation at break was measured as 30.16 ± 2.70 %. The wound dressing gradually released growth factors over 7 days of investigation. Furthermore, the BS significantly outperformed other groups in increasing cell viability and in vivo wound closure rate (95.80 ± 3.47 % after 14 days). Wounds covered with BS healed faster with more collagen deposition and re-epithelialization. The results demonstrate that the BS can be a potential remedy for skin tissue regeneration.

Granulysin-mediated reduction of PDZRN3 induces Cx43 gap junctions activity exacerbating skin damage in trichloroethylene hypersensitivity syndrome

Trichloroethylene (TCE)-induced hypersensitivity syndrome (THS) has been a concern for many researchers in the field of environmental and occupational health. Currently, there is no specific treatment for THS, leaving patients to contend with severe infections arising from extensive skin lesions, consequently leading to serious adverse effects. However, the pathogenesis of severe skin damage in THS remains unclear. This study aims to investigate the specific danger signals and mechanisms underlying skin damage in THS through in vivo and in vitro experiments. We identified that cell supernatant containing 15 kDa granulysin (GNLY), released from activated CD3-CD56+NK cells or CD3+CD56+NKT cells in PBMC induced by TCE or its metabolite, promoted apoptosis in HaCaT cells. The apoptosis level decreased upon neutralization of GNLY in the supernatant by a GNLY-neutralizing antibody in HaCaT cells. Subcutaneous injection of recombinant 15 kDa GNLY exacerbated skin damage in the THS mouse model and better mimicked patients' disease states. Recombinant 15 kDa GNLY could directly induce cellular communication disorders, inflammation, and apoptosis in HaCaT cells. In addition to its cytotoxic effects, GNLY released from TCE-activated NK cells and NKT cells or synthesized GNLY alone could induce aberrant expression of the E3 ubiquitin ligase PDZRN3, causing dysregulation of the ubiquitination of the cell itself. Consequently, this resulted in the persistent opening of gap junctions composed of connexin43, thereby intensifying cellular inflammation and apoptosis through the "bystander effect". This study provides experimental evidence elucidating the mechanisms of THS skin damage and offers a novel theoretical foundation for the development of effective therapies targeting severe dermatitis induced by chemicals or drugs.

An amphibian-derived cathelicidin accelerates cutaneous wound healing through its main regulatory effect on phagocytes

Cathelicidins are an important family of antimicrobial peptides (AMPs) involved in the innate immunity in vertebrates. The mammalian cathelicidins have been well characterized, but the relationship between structure and function in amphibian cathelicidins is still not well understood. In this study, a novel 29-residue cathelicidin antimicrobial peptide (BugaCATH) was identified from the skin of Bufo gargarizans. Unlike other AMPs, BugaCATH does not display any direct antimicrobial effects in vitro. However, it effectively promotes full-thickness wound repair in mice. Following injury, BugaCATH initiates and expedites the inflammatory stage by recruiting neutrophils and macrophages to the wound site. BugaCATH not only regulates neutrophil phagocytic activity but also stimulates the generation of cytokines (TNF-α, IL-6, and IL-1β) and chemokines (CXCL1, CXCL2, CCL2, and CCL3) in macrophages and in mice. Furthermore, it promotes macrophage M2 polarization that facilitates the conversion from a pro-inflammatory macrophage-dominated wound environment to an anti-inflammatory one during the mid to late stages, which is crucial for reducing inflammation and effective wound repair. The MAPK (ERK, JNK, and p38) and NF-κB-NLRP3 signaling pathways are involved in the activity. Moreover, BugaCATH directly enhances the migration of keratinocytes and vascular endothelial cells without affecting their proliferation. Notably, BugaCATH significantly improves the proliferation of keratinocytes and endothelial cells in the presence of macrophages. The current study revealed that in addition to proliferation of keratinocytes and endothelial cells, BugaCATH possesses the ability to modulate inflammatory processes during skin injury through its regulatory effect on phagocytes. The combination of these capabilities makes BugaCATH a potent candidate for skin wound therapy.

Compound Microalgae-Type Biofunctional Hydrogel for Wound Repair during Full-Thickness Skin Injuries

A dual biofunctional hydrogel (HQCS-SP) wound dressing, offering antibacterial properties and a biological response, was innovatively designed and developed to repair full-layer skin defects. The HQCS-SP hydrogel creates an artificial matrix that facilitates cell recruitment, extracellular matrix deposition, exhibiting exceptional tissue affinity, robust self-healing, effective hemostatic capabilities and accelerates wound healing. It is synthesized by crosslinking modified chitosan (HQCS) with spirulina protein (SP) and Fe3+. The HQCS provides antibacterial, antioxidant, good tissue affinity and excellent hemostasis performance. The incorporation of SP not only reinforces the antioxidant, antibacterial, anti-inflammatory, and pro-angiogenesis effects but also participates in the regulation of signal pathways and promotes wound healing. Therefore, this study offers a new visual angle for the design of advanced functional trauma dressings with great application potential in the bio-medical field.

Signaling Pathways Triggering Therapeutic Hydrogels in Promoting Chronic Wound Healing

In recent years, there has been a significant increase in the prevalence of chronic wounds, such as pressure ulcers, diabetic foot ulcers, and venous ulcers of the lower extremities. The main contributors to chronic wound formation are bacterial infection, prolonged inflammation, and peripheral vascular disease. However, effectively treating these chronic wounds remains a global challenge. Hydrogels have extensively explored as wound healing dressing because of their excellent biocompatibility and structural similarity to extracellular matrix (ECM). Nonetheless, much is still unknown how the hydrogels promote wound repair and regeneration. Signaling pathways play critical roles in wound healing process by controlling and coordinating cells and biomolecules. Hydrogels, along with their therapeutic ingredients that impact signaling pathways, have the potential to significantly enhance the wound healing process and its ultimate outcomes. Understanding this interaction will undoubtedly provide new insights into developing advanced hydrogels for wound repair and regeneration. This paper reviews the latest studies on classical signaling pathways and potential targets influenced by hydrogel scaffolds in chronic wound healing. This work hopes that it will offer a different perspective in developing more efficient hydrogels for treating chronic wounds.

Doping proanthocyanidins into gel/zirconium hybrid hydrogel to reshape the microenvironment of diabetic wounds for healing acceleration

Infection and chronic inflammation caused by oxidative stress are major challenges in chronic wound healing. Preparing a simple, efficient hydrogel with reactive oxygen-scavenging properties for chronic wound repair is a promising strategy. Herein, we report an injectable, self-repairing hydrogel with antioxidant and antibacterial properties that can be used to regenerate diabetic wounds. Hydrogels are prepared by coordination crosslinking of gelatin (Gel), a natural biopolymer derived from collagen, with Zr4+. Because of the dynamic properties of metal ion coordination bonds and the bactericidal effect of Zr4+, the obtained coordination hydrogels exhibit self-healing, injectable, and antibacterial properties. The plant polyphenol "proanthocyanidins," which has reactive oxygen-scavenging and anti-inflammatory effects, was simultaneously loaded into the coordination hydrogel during cross-linking. We obtained a versatile hydrogel that is easy to prepare, resistant to mechanical irritation, and antioxidant, and antibacterial in vitro. We further demonstrated that the injectable self-healing hydrogels could effectively repair diabetic skin wounds and accelerate collagen deposition and wound healing. This study shows that the multifunctional antioxidant hydrogel has great potential in developing multifunctional biomaterials for chronic wound healing.

Dual delivery gene-activated scaffold directs fibroblast activity and keratinocyte epithelization

Fibroblasts are the most abundant cell type in dermal skin and keratinocytes are the most abundant cell type in the epidermis; both play a crucial role in wound remodeling and maturation. We aim to assess the functionality of a novel dual gene activated scaffold (GAS) on human adult dermal fibroblasts (hDFs) and see how the secretome produced could affect human dermal microvascular endothelial cells (HDMVECs) and human epidermal keratinocyte (hEKs) growth and epithelization. Our GAS is a collagen chondroitin sulfate scaffold loaded with pro-angiogenic stromal derived factor (SDF-1α) and/or an anti-aging β-Klotho plasmids. hDFs were grown on GAS for two weeks and compared to gene-free scaffolds. GAS produced a significantly better healing outcome in the fibroblasts than in the gene-free scaffold group. Among the GAS groups, the dual GAS induced the most potent pro-regenerative maturation in fibroblasts with a downregulation in proliferation (twofold, p < 0.05), fibrotic remodeling regulators TGF-β1 (1.43-fold, p < 0.01) and CTGF (1.4-fold, p < 0.05), fibrotic cellular protein α-SMA (twofold, p < 0.05), and fibronectin matrix deposition (twofold, p < 0.05). The dual GAS secretome also showed enhancements of paracrine keratinocyte pro-epithelializing ability (1.3-fold, p < 0.05); basement membrane regeneration through laminin (6.4-fold, p < 0.005) and collagen IV (8.7-fold, p < 0.005) deposition. Our findings demonstrate enhanced responses in dual GAS containing hDFs by proangiogenic SDF-1α and β-Klotho anti-fibrotic rejuvenating activities. This was demonstrated by activating hDFs on dual GAS to become anti-fibrotic in nature while eliciting wound repair basement membrane proteins; enhancing a proangiogenic HDMVECs paracrine signaling and greater epithelisation of hEKs.

Solanum lycopersicum (Tomato)-Derived Nanovesicles Accelerate Wound Healing by Eliciting the Migration of Keratinocytes and Fibroblasts

Plant-derived nanovesicles have been considered interesting in medicine for their breakthrough biological effects, including those relevant to wound healing. However, tomato-derived nanovesicles (TDNVs) have not been studied for their effects on wound closure yet. TDNVs were isolated from Solanum lycopersicum (var. Piccadilly) ripe tomatoes by ultracentrifugation. Extract (collected during the isolation procedure) and NVs (pellet) were characterized by transmission electron microscopy and laser Doppler electrophoresis. Wound healing in the presence of Extract or NVs was analyzed by a scratch assay with monocultures of human keratinocytes (HUKE) or NIH-3T3 mouse fibroblasts. Cell proliferation and migration were studied by MTT and agarose spot assay, respectively. The vesicles in the Extract and NV samples were nanosized with a similar mean diameter of 115 nm and 130 nm, respectively. Both Extract and NVs had already accelerated wound closure of injured HUKE and NIH-3T3 monocultures by 6 h post-injury. Although neither sample exerted a cytotoxic effect on HUKE and NIH-3T3 fibroblasts, they did not augment cell proliferation. NVs and the Extract increased cell migration of both cell types. NVs from tomatoes may accelerate wound healing by increasing keratinocyte and fibroblast migration. These results indicate the potential therapeutic usefulness of TDNVs in the treatment of chronic or hard-to-heal ulcers.

Using halofuginone-silver thermosensitive nanohydrogels with antibacterial and anti-inflammatory properties for healing wounds infected with Staphylococcus aureus

Contamination by pathogens, such as bacteria, can irritate a wound and prevent its healing, which may affect the physical fitness of the infected person. As such, the development of more novel nano-biomaterials able to cope with the inflammatory reaction to bacterial infection during the wound healing process to accelerate wound healing is required. Herein, a halofuginone‑silver nano thermosensitive hydrogel (HTPM&AgNPs-gel) was prepared via a physical swelling method. HTPM&AgNPs-gel was characterized based on thermogravimetric analysis, differential scanning calorimetry, morphology, injectability, and rheological mechanics that reflected its exemplary nature. Moreover, HTPM&AgNPs-gel was further tested for its ability to facilitate healing of skin fibroblasts and exert antibacterial activity. Finally, HTPM&AgNPs-gel was tested for its capacity to accelerate general wound healing and treat bacterially induced wound damage. HTPM&AgNPs-gel appeared spherical under a transmission electron microscope and showed a grid structure under a scanning electron microscope. Additionally, HTPM&AgNPs-gel demonstrated excellent properties, including injectability, temperature-dependent swelling behavior, low loss at high temperatures, and appropriate rheological properties. Further, HTPM&AgNPs-gel was found to effectively promote healing of skin fibroblasts and inhibit the proliferation of Escherichia coli and Staphylococcus aureus. An evaluation of the wound healing efficacy demonstrated that HTPM&AgNPs-gel had a more pronounced ability to facilitate wound repair and antibacterial effects than HTPM-gel or AgNPs-gel alone, and exhibited ideal biocompatibility. Notably, HTPM&AgNPs-gel also inhibited inflammatory responses in the healing process. HTPM&AgNPs-gel exhibited antibacterial, anti-inflammatory, and scar repair features, which remarkably promoted wound healing. These findings indicated that HTPM&AgNPs-gel holds great clinical potential as a promising and valuable wound healing treatment.

Management of wounds in diabetes by administering allicin and quercetin in emulsion form as wound medicine in diabetic rat models

Wounds in diabetes is a complex problem that requires effective treatment at a high cost. Adjuvant therapy from natural bioactive elements can be an alternative to overcome problems in diabetic wound healing disorders. Allicin and quercetin are natural bioactive substances contained in several fruit or vegetable plants that have various pharmacological effects. The purpose of this study was to determine the effect of allicin and quercetin in emulsion form as wound medicine in helping the wound healing process. Diabetic wistar rats with wounds on their backs measuring 1 × 1 cm were divided into four treatment groups which were given wound medicine once a day for seven days according to their distribution. The wound healing process was evaluated on the third and seventh day. Data were observed and analyzed using appropriate statistical tools. Measurement of wound healing indicators was carried out by examining wound contraction and histopathological examination showing that the treatment group given the allicin and quercetin formula experienced an improvement compared to the treatment group without allicin and quercetin. Allicin and quercetin increase the percentage of wound contraction, increase the density of blood vessels and the epithelialization process in the wound so that the wound healing process becomes faster. In conclusion, allicin and quercetin can be effective adjuvant therapies in helping wound healing in diabetes. Wound medication in the form of an emulsion is an effective choice, because it can maintain the stability of the allicin and quercetin content and can make the wound environment moist.

Protein-based bioactive coatings: from nanoarchitectonics to applications

Protein-based bioactive coatings have emerged as a versatile and promising strategy for enhancing the performance and biocompatibility of diverse biomedical materials and devices. Through surface modification, these coatings confer novel biofunctional attributes, rendering the material highly bioactive. Their widespread adoption across various domains in recent years underscores their importance. This review systematically elucidates the behavior of protein-based bioactive coatings in organisms and expounds on their underlying mechanisms. Furthermore, it highlights notable advancements in artificial synthesis methodologies and their functional applications in vitro. A focal point is the delineation of assembly strategies employed in crafting protein-based bioactive coatings, which provides a guide for their expansion and sustained implementation. Finally, the current trends, challenges, and future directions of protein-based bioactive coatings are discussed.

Two-Dimensional Biodegradable Black Phosphorus Nanosheets Promote Large Full-Thickness Wound Healing through In Situ Regeneration Therapy

Large full-thickness skin lesions have been one of the most challenging clinical problems in plastic surgery repair and reconstruction. To achieve in situ skin regeneration and perfect clinical outcomes, we must address two significant obstacles: angiogenesis deficiency and inflammatory dysfunction. Recently, black phosphorus has shown great promise in wound healing. However, few studies have explored the bio-effects of BP to promote in situ skin regeneration based on its nanoproperties. Here, to investigate whether black phosphorus nanosheets have positive bio-effects on in situ skin repair, we verified black phosphorus nanosheets' positive effects on angiogenic and anti-inflammatory abilities in vitro. Next, the in vivo evaluation performed on the rat large full-thickness excisional wound splinting model more comprehensively showed that the positive bio-effects of black phosphorus nanosheets are multilevel in wound healing, which can effectively enhance anti-inflammatory ability, angiogenesis, collagen deposition, and skin re-epithelialization. Then, multiomics analysis was performed to explore further the mechanism of black phosphorus nanosheets' regulation of endothelial cells in depth. Molecular mechanistically, black phosphorus nanosheets activated the JAK-STAT-OAS signaling pathway to promote cellular function and mitochondrial energy metabolism in endothelial cells. This study can provide a theoretical basis for applying two-dimensional black phosphorus nanosheets as nanomedicine to achieve in situ tissue regeneration in complex human pathological microenvironments, guiding the subsequent optimization of black phosphorus.

Enhancing Human Cutaneous Wound Healing through Targeted Suppression of Large Conductance Ca2+-Activated K+ Channels

The modulation of K+ channels plays a crucial role in cell migration and proliferation, but the effect of K+ channels on human cutaneous wound healing (CWH) remains underexplored. This study aimed to determine the necessity of modulating K+ channel activity and expression for human CWH. The use of 25 mM KCl as a K+ channel blocker markedly improved wound healing in vitro (in keratinocytes and fibroblasts) and in vivo (in rat and porcine models). K+ channel blockers, such as quinine and tetraethylammonium, aided in vitro wound healing, while Ba2+ was the exception and did not show similar effects. Single-channel recordings revealed that the Ba2+-insensitive large conductance Ca2+-activated K+ (BKCa) channel was predominantly present in human keratinocytes. NS1619, an opener of the BKCa channel, hindered wound healing processes like proliferation, migration, and filopodia formation. Conversely, charybdotoxin and iberiotoxin, which are BKCa channel blockers, dramatically enhanced these processes. The downregulation of BKCa also improved CWH, whereas its overexpression impeded these healing processes. These findings underscore the facilitative effect of BKCa channel suppression on CWH, proposing BKCa channels as potential molecular targets for enhancing human cutaneous wound healing.

The efficacy of adipose-derived stem cells in burn injuries: a systematic review

BACKGROUND

Burn injuries can be associated with prolonged healing, infection, a substantial inflammatory response, extensive scarring, and eventually death. In recent decades, both the mortality rates and long-term survival of severe burn victims have improved significantly, and burn care research has increasingly focused on a better quality of life post-trauma. However, delayed healing, infection, pain and extensive scar formation remain a major challenge in the treatment of burns. ADSCs, a distinct type of mesenchymal stem cells, have been shown to improve the healing process. The aim of this review is to evaluate the efficacy of ADSCs in the treatment of burn injuries.

METHODS

A systematic review of the literature was conducted using the electronic databases PubMed, Web of Science and Embase. The basic research question was formulated with the PICO framework, whereby the usage of ADSCs in the treatment of burns in vivo was determined as the fundamental inclusion criterion. Additionally, pertinent journals focusing on burns and their treatment were screened manually for eligible studies. The review was registered in PROSPERO and reported according to the PRISMA statement.

RESULTS

Of the 599 publications screened, 21 were considered relevant to the key question and were included in the present review. The included studies were almost all conducted on rodents, with one exception, where pigs were investigated. 13 of the studies examined the treatment of full-thickness and eight of deep partial-thickness burn injuries. 57,1 percent of the relevant studies have demonstrated that ADSCs exhibit immunomodulatory effects during the inflammatory response. 16 studies have shown improved neovascularisation with the use of ADSCs. 14 studies report positive influences of ADSCs on granulation tissue formation, while 11 studies highlight their efficacy in promoting re-epithelialisation. 11 trials demonstrated an improvement in outcomes during the remodelling phase.

CONCLUSION

In conclusion, it appears that adipose-derived stem cells demonstrate remarkable efficacy in the field of regenerative medicine. However, the usage of ADSCs in the treatment of burns is still at an early experimental stage, and further investigations are required in order to examine the potential usage of ADSCs in future clinical burn care.

Skin benefits of postbiotics derived from Micrococcus luteus derived from human skin: an untapped potential for dermatological health

BACKGROUND

The skin microbiome, a diverse community of microorganisms, plays a crucial role in maintaining skin health. Among these microorganisms, the gram-positive bacterium Micrococcus luteus exhibits potential for promoting skin health. This study focuses on postbiotics derived from M. luteus YM-4, a strain isolated from human skin.

OBJECTIVE

Our objective is to explore the beneficial effects of YM-4 culture filtrate on dermatological health, including enhancing barrier function, modulating immune response, and aiding recovery from environmental damage.

METHODS

The effects of the YM-4 culture filtrate were tested on human keratinocytes and fibroblasts under various conditions using real-time PCR for gene expression analysis and fibroblast migration assays. A dehydration-simulated model was employed to prepare RNA-Seq samples from HaCaT cells treated with the YM-4 culture filtrate. Differentially expressed genes were identified and functionally classified through k-means clustering, gene ontology terms enrichment analyses, and protein-protein interactions mapping.

RESULTS

The YM-4 culture filtrate enhanced the expression of genes involved in skin hydration, hyaluronic acid synthesis, barrier function, and cell proliferation. It also reduced inflammation markers in keratinocytes and fibroblasts under stress conditions. It mitigated UVB-induced collagen degradation while promoted collagen synthesis, suggesting anti-aging properties, and accelerated wound healing processes by promoting cell proliferation and migration. RNA sequencing analysis revealed that the YM-4 culture filtrate could reverse dehydration-induced transcriptional changes towards a state similar to untreated cells.

CONCLUSION

M. luteus YM-4 culture filtrate exhibits significant therapeutic potential for dermatological applications.

Conjugated Polymer Composite Nanoparticles Augmenting Photosynthesis-Based Light-Triggered Hydrogel Promotes Chronic Wound Healing

Diabetic chronic wounds are characterized by local hypoxia, impaired angiogenesis, and bacterial infection. In situ, self-supply of dissolved oxygen combined with the elimination of bacteria is urgent and challenging for chronic nonhealing wound treatment. Herein, an oxygen-generating system named HA-L-NB/PFE@cp involving biological photosynthetic chloroplasts (cp)/conjugated polymer composite nanoparticles (PFE-1-NPs@cp) and light-triggered hyaluronic acid-based (HA-L-NB) hydrogel for promoting diabetic wound healing is introduced. Briefly, conjugated polymer nanoparticles (PFE-1-NPs) possess unique light harvesting ability, which accelerates the electron transport rates in photosystem II (PS II) by energy transfer, elevating photosynthesis beyond natural chloroplasts. The enhanced release of oxygen can greatly relieve hypoxia, promote cell migration, and favor antibacterial photodynamic therapy. Additionally, the injectable hydrogel precursors are employed as a carrier to deliver PFE-1-NPs@cp into the wound. Under light irradiation, they quickly form a gel by S-nitrosylation coupling reaction and in situ anchor on tissues through amine-aldehyde condensation. Both in vitro and in vivo assays demonstrate that the oxygen-generating system can simultaneously relieve wound hypoxia, eliminate bacteria, and promote cell migration, leading to the acceleration of wound healing. This study provides a facile approach to develop an enhanced oxygen self-sufficient system for promoting hypoxic tissue, especially diabetic wound healing.

Reepithelialization of Diabetic Skin and Mucosal Wounds Is Rescued by Treatment With Epigenetic Inhibitors

Wound healing is a complex, highly regulated process and is substantially disrupted by diabetes. We show here that human wound healing induces specific epigenetic changes that are exacerbated by diabetes in an animal model. We identified epigenetic changes and gene expression alterations that significantly reduce reepithelialization of skin and mucosal wounds in an in vivo model of diabetes, which were dramatically rescued in vivo by blocking these changes. We demonstrate that high glucose altered FOXO1-matrix metallopeptidase 9 (MMP9) promoter interactions through increased demethylation and reduced methylation of DNA at FOXO1 binding sites and also by promoting permissive histone-3 methylation. Mechanistically, high glucose promotes interaction between FOXO1 and RNA polymerase-II (Pol-II) to produce high expression of MMP9 that limits keratinocyte migration. The negative impact of diabetes on reepithelialization in vivo was blocked by specific DNA demethylase inhibitors in vivo and by blocking permissive histone-3 methylation, which rescues FOXO1-impaired keratinocyte migration. These studies point to novel treatment strategies for delayed wound healing in individuals with diabetes. They also indicate that FOXO1 activity can be altered by diabetes through epigenetic changes that may explain other diabetic complications linked to changes in diabetes-altered FOXO1-DNA interactions.

ARTICLE HIGHLIGHTS

FOXO1 expression in keratinocytes is needed for normal wound healing. In contrast, FOXO1 expression interferes with the closure of diabetic wounds. Using matrix metallopeptidase 9 as a model system, we found that high glucose significantly increased FOXO1-matrix metallopeptidase 9 interactions via increased DNA demethylation, reduced DNA methylation, and increased permissive histone-3 methylation in vitro. Inhibitors of DNA demethylation and permissive histone-3 methylation improved the migration of keratinocytes exposed to high glucose in vitro and the closure of diabetic skin and mucosal wounds in vivo. Inhibition of epigenetic enzymes that alter FOXO1-induced gene expression dramatically improves diabetic healing and may apply to other conditions where FOXO1 has a detrimental role in diabetic complications.

Lavandula stoechas extract incorporated polylactic acid nanofibrous mats as an antibacterial and cytocompatible wound dressing

In recent years, great efforts have been devoted to the design and production of bioactive wound dressings that promote skin regeneration and prevent infection. Many plant extracts and essential oils have been widely accepted in traditional medicine for a wide variety of medicinal purposes, especially wound healing. Over the past decade, many studies have focused on manufacturing and designing wound dressings containing plant compounds and extracts. In this study, Lavandula stoechas extract (LSE) (0.25 %, 0.5 %, and 1%wt) incorporated-polylactic acid (PLA) nanofibrous mats were successfully produced and characterized. Microstructural analysis by SEM revealed that the fiber diameter changed with the increase in the amount of LSE. Also, the nanofibrous mats were evaluated for their in vitro antibacterial, cytotoxicity, and wound healing properties for their use as a wound dressing material. According to the results of the disc diffusion test, PLA nanofibrous mats containing LSE %1 showed 9.65 ± 0.46 and 7.37 ± 0.03 inhibition zone (mm) against E. coli and S. aureus, respectively. According to the results of the in vitro wound healing assay, mats containing 0.5 % LSE showed better-wound closure activity compared to the control. Our results show that LSE-incorporated nanofibrous dressings can be an effective alternative with good antimicrobial activity.

A polyglutamic acid/tannic acid-based nano drug delivery system: Antibacterial, immunoregulation and sustained therapeutic strategies for oral ulcers

Oral ulcers are a common inflammatory mucosal ulcer, and the moist and dynamic environment in the oral cavity makes topical pharmacological treatment of oral ulcers challenging. Herein, oral ulcer tissue adhesion nanoparticles were prepared by using esterification reaction between polyglutamic acid and tannic acid, and at the same time doxycycline hydrochloride was loaded into the nanoparticles. The obtained slow drug release effect of the drug-loaded nanoparticles reduced the toxicity of the drug, and by penetrating into the fine crevice region of the wound tissue and adhering to it, they could in-situ release the carried drug more effectively and thus have shown significant antibacterial effects. In addition, tannic acid in the system conferred adhesion, antioxidant and immune regulation activities to the nanocarriers. A rat oral ulcer model based on fluorescent labeling was established to investigate the retention of nanoparticles at the ulcer, and the results showed that the retention rate of drug-loaded nanoparticles at the ulcer was 17 times higher than that of pure drug. Due to the antibacterial and immune regulation effects of the drug-loaded nanoparticles, the healing of oral ulcer wounds was greatly accelerated. Such application of doxycycline hydrochloride loaded polyglutamic acid/tannic acid nanoparticles is a novel and effective treatment strategy for oral ulcer.

Targeting DNA methylation and demethylation in diabetic foot ulcers

BACKGROUND

Poor wound healing is a significant complication of diabetes, which is commonly caused by neuropathy, trauma, deformities, plantar hypertension and peripheral arterial disease. Diabetic foot ulcers (DFU) are difficult to heal, which makes patients susceptible to infections and can ultimately conduce to limb amputation or even death in severe cases. An increasing number of studies have found that epigenetic alterations are strongly associated with poor wound healing in diabetes.

AIM OF REVIEW

This work provides significant insights into the development of therapeutics for improving chronic diabetic wound healing, particularly by targeting and regulating DNA methylation and demethylation in DFU. Key scientific concepts of review: DNA methylation and demethylation play an important part in diabetic wound healing, via regulating corresponding signaling pathways in different breeds of cells, including macrophages, vascular endothelial cells and keratinocytes. In this review, we describe the four main phases of wound healing and their abnormality in diabetic patients. Furthermore, we provided an in-depth summary and discussion on how DNA methylation and demethylation regulate diabetic wound healing in different types of cells; and gave a brief summary on recent advances in applying cellular reprogramming techniques for improving diabetic wound healing.

Preparation of Multi-Functional Quaternary Ammonium Chitosan/Surfactin Hydrogel and its Application in Wound Management

Hydrogel with a 3D network structure can cover the wound to stop the bleeding and support the host tissue infiltration and integration. In this study, an antibacterial hydrogel with hemostasis and the ability to promote wound healing is proposed. This hydrogel comprised surfactin, polyvinylpyrrolidone, and methacrylic anhydride (MA) grafted quaternary ammonium chitosan (CS-MA). The hydrogel formation is triggered by the ultraviolet-initiated polymerization of CS-MA, while the surfactin is complexed with the hydrogel through hydrogen bonding interaction. The results showed that this hydrogel is an adhesive hydrogel with shape adaptability, which can cover the wound surface and promote contact between the hydrogel and the wound surface. More importantly, this hydrogel can simulate the microenvironment of the primary extracellular matrix and increase collagen deposition, and inflammatory factor transformation. The designing of such a multi-functional hydrogel is expected to provide a novel approach to promoting the healing of wounds.

Neuro-Inspired Biomimetic Microreactor for Sensory Recovery and Hair Follicle Neogenesis under Skin Burns

Deep burns are one of the most severe skin wounds, with typical symptoms being a contradiction between initial severe pain and a subsequent loss of sensation. Although it has long been known that sensory nerves promote skin regeneration and modulate skin function, no proven burn management strategies target sensory nerves. Here, a neuro-inspired biomimetic microreactor is designed based on the immune escape outer membrane of neuroblastoma cells and neural-associated intracellular proteins. The microreactor is constructed on a metal-organic framework (MOF) with a neuroblastoma membrane coating the surface and intracellular proteins loaded inside, called Neuro-MOF. It is loaded into a therapeutic hydrogel and triggers the release of its content proteins upon excitation by near-infrared light. The proteins compensate the skin microenvironment for permanent neurological damage after burns to initiate peripheral nerve regeneration and hair follicle niche formation. In addition, the neuroblastoma cell membrane is displayed on the surface of the Neuro-MOF microreactor, decreasing its immunogenicity and suppressing local inflammation. In a mouse model of deep skin burns, the Neuro-MOF microreactor exhibited significant functional skin regeneration effects, particularly sensory recovery and hair follicle neogenesis.

Angiogenesis, hemocompatibility and bactericidal effect of bioactive natural polymer-based bilayer adhesive skin substitute for infected burned wound healing

Thermal wounds are complex and lethal with irregular shapes, risk of infection, slow healing, and large surface area. The mortality rate in patients with infected burns is twice that of non-infected burns. Developing multifunctional skin substitutes to augment the healing rate of infected burns is vital. Herein, we 3D printed a hydrogel scaffold comprising carboxymethyl chitosan (CMCs) and oxidized alginate grafted catechol (O-AlgCat) on a hydrophobic electrospun layer, forming a bilayer skin substitute (BSS). The functional layer (FL) was fabricated by physiochemical crosslinking to ensure favorable biodegradability. The gallium-containing hydrophobic electrospun layer or backing layer (BL) could mimic the epidermis of skin, avoiding fluid penetration and offering antibacterial activity. 3D printed FL contains catechol, gallium, and biologically active platelet rich fibrin (PRF) to adhere to both tissue and BL, show antibacterial activity, encourage angiogenesis, cell growth, and migration. The fabricated bioactive BSS exhibited noticeable adhesive properties (P ≤ 0.05), significant antibacterial activity (P ≤ 0.05), faster clot formation, and the potential to promote proliferation (P ≤ 0.05) and migration (P ≤ 0.05) of L929 cells. Furthermore, the angiogenesis was significantly higher (P ≤ 0.05) when evaluated in vivo and in ovo. The BSS-covered wounds healed faster due to low inflammation and high collagen density. Based on the obtained results, the fabricated bioactive BSS could be an effective treatment for infected burn wounds.

Secretome of stem cells from human exfoliated deciduous teeth (SHED) and its extracellular vesicles improves keratinocytes migration, viability, and attenuation of H2 O2 -induced cytotoxicity

Therapies for wound healing using the secretome and extracellular vesicles (EVs) of mesenchymal stem/stromal cells have been shown to be successful in preclinical studies. This study aimed to characterise the protein content of the secretome from stem cells from human exfoliated deciduous teeth (SHED) and analyse the in vitro effects of SHED-conditioned medium (SHED-CM) and SHED extracellular vesicles (SHED-EVs) on keratinocytes. EVs were isolated and characterised. The keratinocyte viability and migration of cells treated with SHED-EVs and conditioned medium (CM) were evaluated. An HaCaT apoptosis model induced by H2 O2 in vitro was performed with H2 O2 followed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and live/dead assays. Finally, the expression of vascular endothelial growth factor (VEGF) in keratinocytes treated with secretome and EVs was evaluated by immunofluorescence staining and confirmed with RT-qPCR. SHED-EVs revealed a cup-shaped morphology with expression of the classical markers for exosomes CD9 and CD63, and a diameter of 181 ± 87 nm. The internalisation of EVs by HaCaT cells was confirmed by fluorescence microscopy. Proteomic analysis identified that SHED-CM is enriched with proteins related to stress response and development, including cytokines (CXCL8, IL-6, CSF1, CCL2) and growth factors (IGF2, MYDGF, PDGF). The results also indicated that 50% CM and 0.4-0.6 μg/mL EVs were similarly efficient for improving keratinocyte viability, migration, and attenuation of H2 O2 -induced cytotoxicity. Additionally, expression of VEGF on keratinocytes increased when treated with SHED secretome and EVs. Furthermore, VEGF gene expression in keratinocytes increased significantly when treated with SHED secretome and EVs. Both SHED-CM and SHED-EVs may therefore be promising therapeutic tools for accelerating re-epithelialization in wound healing.

Wound-Induced Hair Follicle Neogenesis as a Promising Approach for Hair Regeneration

The mammalian skin contains hair follicles, which are epidermal appendages that undergo periodic cycles and exhibit mini-organ features, such as discrete stem cell compartments and different cellular components. Wound-induced hair follicle neogenesis (WIHN) is the remarkable ability to regenerate hair follicles after large-scale wounding and occurs in several adult mammals. WIHN is comparable to embryonic hair follicle development in its processes. Researchers are beginning to identify the stem cells that, in response to wounding, develop into neogenic hair follicles, as well as to understand the functions of immune cells, mesenchymal cells, and several signaling pathways that are essential for this process. WIHN represents a promising therapeutic approach to the reprogramming of cellular states for promoting hair follicle regeneration and preventing scar formation. In the scope of this review, we investigate the contribution of several cell types and molecular mechanisms to WIHN.

Mesenchymal stem cell-derived secretomes-enriched alginate/ extracellular matrix hydrogel patch accelerates skin wound healing

BACKGROUND

The secretomes of mesenchymal stem cells (MSCs) have great therapeutic potential and thereby their efficient delivery into the target site is of particular interest. Here, we propose a new strategy of hMSCs-derived secretomes delivery for advanced wound healing upon harnessing the working principle of extracellular matrix (ECM)-growth factors interaction in vivo.

METHODS

We prepared an alginate hydrogel based wound patch, where it contains both human MSC-derived secretomes and ECM. The ECM was obtained from the decellularization of in vitro cultured human lung fibroblasts. The alginate solution was blended with ECM suspension, crosslinked, air-dried, then rehydrated with the secretomes contained in the concentrated conditioned media (CCM) as a highly saturated form of conditioned media (CM). We tested four different groups, with or without the ECM to investigate not only the role of ECM but the therapeutic effect of secretomes.

RESULTS

The secretomes reserved many, diverse bioactive factors, such as VEGF, HGF, IGFBPs, IL-6, and IL-8. Alginate/ECM/CCM (AEC) patch could hold significantly larger amount of secretomes and release them longer than the other groups. Our AEC patch was the most effective in stimulating not only cell migration and proliferation but the collagen synthesis of dermal fibroblasts in vitro. Moreover, the AEC patch-treated full-thickness skin wounds disclosed significantly better wound healing indications: cell recruitment, neovascularization, epidermis thickness, keratinocyte migration, and mature collagen deposition, as assessed via histology (H&E, Herovici staining) and immunofluorescence, respectively. In particular, our AEC patch enabled a phenotype shift of myofibroblast into fibroblast over time and led to mature blood vessel formation at 14 day.

CONCLUSIONS

We believe that ECM certainly contributed to generate a secretomes-enriched milieu via ECM-secretomes interactions and thereby such secretomes could be delivered more efficiently, exerting significant therapeutic impact either individually or collectively during wound healing process.