Skin Wound Healing: Normal Macrophage Function and Macrophage Dysfunction in Diabetic Wounds

Transplanted artificial amnion membrane enhanced wound healing in third-degree burn injury diabetic mouse model

Introduction

Wound healing is severely compromised in patients with diabetes owing to factors such poor blood circulation, delayed immune response, elevated blood sugar levels, and neuropathy. Although the development of new wound healing products and prevention of serious complications such as infections in wounds have received substantial interest, wound healing remains a challenge in regenerative medicine. Burn wounds, especially third-degree burns, are difficult to treat because they are associated with immune and inflammatory reactions and distributive shock. Wound care and treatment that protects the burn site from infection and allows wound healing can be achieved with bioengineered wound dressings. However, few studies have reported effective dressings for third-degree burn wounds, making it important to develop new dressing materials.

Methods

In this study, we developed an artificial amniotic membrane (AM) using epithelial and mesenchymal cells derived from human amnion as a novel dressing material. The artificial AM was applied to the wound of a diabetic third-degree burn model and its wound healing ability was evaluated.

Results

This artificial amnion produced multiple growth factors associated with angiogenesis, fibroblast proliferation, and anti-inflammation. In addition, angiogenesis and granulation tissue formation were promoted in the artificial AM-treated mouse group compared with the control group. Furthermore, the inflammatory phase was prolonged in the control group.

Conclusions

Our preliminary results indicate that the artificial AM might be useful as a new dressing for refractory ulcers and third-degree burns. This artificial AM-based material represents great potential for downstream clinical research and treatment of diabetes patients with third-degree burns.

Synergistic berberine chloride and Curcumin-Loaded nanofiber therapies against Methicillin-Resistant Staphylococcus aureus Infection: Augmented immune and inflammatory responses in zebrafish wound healing

BACKGROUND

Wound healing pivots on a finely orchestrated inflammatory cascade, critical for tissue repair. Chronic wounds, compounded by persistent inflammation and susceptibility to infection, pose formidable clinical challenges. Nanofiber dressings offer promising avenues for wound care, yet their interaction with inflammation and infection remains elusive. We aim to delineate the inflammatory cascade preceding wound closure and assess Cu@Bbc nanofibers' therapeutic efficacy in mitigating inflammation and combating infection. Their unique attributes suggest promise in modulating inflammation, fostering tissue regeneration, and preventing microbial colonization. Investigating the intricate interplay between nanofiber scaffolds, inflammation, and infection may unveil mechanisms of enhanced wound healing. Our findings could stimulate the development of tailored dressings, urgently needed for effective wound management amidst immune dysregulation, infection, and inflammation.

METHODS

In this investigation, we synthesized Cu@Bbc nanofibers, incorporating curcumin and berberine chloride, for wound healing applications. We evaluated their individual and combined antibacterial, anti-biofilm, and antioxidant activities, alongside binding affinity with pro-inflammatory cytokines through molecular docking. Morphological characterization was conducted via SEM, FTIR assessed functional groups, and wettability contact angle measured hydrophobic properties. The physical properties, including tensile strength, swelling behavior, and thermal stability, were evaluated using tensile testing, saline immersion method and thermogravimetric analysis. Biodegradability of the nanofibers was assessed through a soil burial test. Biocompatibility was determined via MTT assay, while wound healing efficacy was assessed with in vitro scratch assays. Controlled drug release and antibacterial activity against MRSA were examined, with in vivo assessment in a zebrafish model elucidating inflammatory responses and tissue remodeling.

RESULTS

In this study, the synergistic action of curcumin and berberine chloride exhibited potent antibacterial efficacy against MRSA, with significant anti-mature biofilm disruption. Additionally, the combination demonstrated heightened antioxidant potential. Molecular docking studies revealed strong binding affinity with pro-inflammatory cytokines, suggesting a role in expediting the inflammatory response crucial for wound healing. Morphological analysis confirmed nanofiber quality, with drug presence verified via FTIR spectroscopy. Cu@Bbc demonstrated higher tensile strength, optimal swelling behavior, and robust thermal stability as evaluated through tensile testing and thermogravimetric analysis. Additionally, the Cu@Bbc nanofiber showed enhanced biodegradability, as confirmed by the soil burial test. Biocompatibility assessments showed favorable compatibility, while in vitro studies demonstrated potent antibacterial activity. In vivo zebrafish experiments revealed accelerated wound closure, re-epithelialization, and heightened immune response, indicative of enhanced wound healing.

CONCLUSION

In summary, our investigation highlights the efficacy of Cu@Bbc nanofibers, laden with curcumin and berberine chloride, in displaying robust antibacterial and antioxidant attributes while also modulating immune responses and inflammatory cascades essential for wound healing. These results signify their potential as multifaceted wound dressings for clinical implementation.

The ASB@HNTs-PVA nanofiber membrane, possessing both anti-inflammatory and hemostatic activities, promotes the healing of T2D skin wounds

The healing of diabetic wounds has long been a significant challenge in the field of medicine. The elevated sugar levels surrounding diabetic wounds create a conducive environment for harmful bacterial growth, resulting in purulent infections that impede the healing process. Thus, the development of a biomaterial that can enhance the healing of diabetic wounds holds great importance. This study developed electrospun dressings for wound healing by combining traditional Chinese medicine and clay. The study utilized electrospinning technology to prepare polyvinyl alcohol (PVA) nanofiber membranes containing ASB and HNTs. These ASB@HNTs-PVA nanofiber membranes demonstrated rapid hemostasis, along with antibacterial and anti-inflammatory properties, facilitating the recovery of type 2 diabetic (T2D) wounds. Various analyses were conducted to assess the performance of the composite nanofiber membrane, including investigations into its biocompatibility and hemostatic abilities through antibacterial experiments, cell experiments, and mouse liver tail bleeding experiments. Western blot analysis confirmed that the composite nanofiber membrane could decrease the levels of inflammatory factors IL-1β and TNF-α. A type 2 diabetic mouse model was utilized, with wounds artificially induced on the backs of mice. Application of the nanofiber membrane to the wounds further confirmed its anti-inflammatory effects and ability to enhance wound healing in vivo.

Mechanism of DT-13 regulating macrophages in diabetic wound healing

BACKGROUND

Diabetes is a complex metabolic system disease, and one of the main reasons why it is difficult to heal is that macrophages cannot realize the transition from pro-inflammatory M1 phenotype to anti-inflammatory M2 phenotype. Liriope spicata Lour. is a traditional Chinese medicine. According to the theory of traditional Chinese medicine, Liriope spicata Lour. has nourishing Yin Sheng Jin, moistening lung clear heart, used for lung dryness dry cough, Yin deficiency cough, throat arthralgia throat pain, thirst, internal heat thirst, upset insomnia, intestinal dryness constipation, is the classification of Yin tonifying drugs. Liriope muscari baily saponins C (DT-13) is one of the main active ingredients of Liriope spicata Lour., has significant anti-inflammatory, anti-tumor, and immunomodulatory effects. This thesis aims to explore the role of DT-13 in angiogenesis by regulating the polarization of macrophages, and ultimately play an anti-inflammatory role in regeneration by regulating immune cells.

METHODS

We conducted in vivo experiments using a diabetic mouse ulcer model to verify the effect of DT-13 in promoting wound healing. Spatial transcriptome sequencing technology was utilized to perform RNA transcript analysis on wound tissues from type II diabetic mice and non-diabetic mice. Subsequently, we used the CCK-8 assay to evaluate the impact of DT-13 on the viability of THP-1 cells (human monocytes). ELISA, immunofluorescence, and Western blot techniques were employed to study the mechanisms by which DT-13 inhibits the sustained inflammation and polarization process of M1 macrophages induced by LPS. The Transwell assay was used to assess the influence of DT-13 treatment on the co-culture of M1 macrophages induced by LPS under high glucose conditions with HUVEC cells. Finally, the chick embryo chorioallantoic membrane (CAM) assay was applied to explore the effects of DT-13 on angiogenesis stimulated by M1 macrophages under high glucose conditions with LPS stimulation.

RESULTS

We found that DT-13 can promote wound healing in a diabetic ulcer model in mice. Through spatial transcriptome sequencing results, we discovered that type II diabetic mice had higher levels of inflammation at the wound site and abnormal expression of macrophage characteristic proteins. The CCK-8 assay detected that DT-13 at 20 μmol/L had an effect on THP-1 cells. Through Q-PCR, ELISA, immunofluorescence, and Western blot results, we found that the mechanism by which DT-13 exerts anti-inflammatory effects on M1 macrophages with sustained inflammation induced by LPS under high glucose conditions may be through the TLR4-NFKB signaling pathway, and the mechanism for inducing the polarization of M1 macrophages to M2 type may be through the ERK-STAT3 signaling pathway. Interestingly, through the Transwell assay, we found that M1 macrophages induced by LPS under high glucose conditions, after treatment with DT-13 and co-cultured with HUVECs, could increase the migratory ability of HUVEC cells. This indicates that M1 macrophages induced by LPS under high glucose conditions, after treatment with DT-13, can promote angiogenesis.

CONCLUSION

DT-13 can significantly promote healing wounds in diabetic mice, and its mechanism may be to participate in promoting the formation of blood vessels by changing the polarization of macrophages.

Diphasic CeO2 Nanocrystal/Bioactive Glass Nanosphere-Based Composite Hydrogel for Diabetic Wound Healing by Reactive Oxygen Species Scavenging and Inflammation Regulation

Background: Antioxidant therapy aimed at reducing excessive local oxidative stress is one of the most important strategies for promoting diabetic wound repair. The reversible transformation of Ce3+/Ce4+ in ceria (CeO2) can reduce excessive local oxidative stress. However, inducing angiogenesis, local anti-inflammatory effects, and other positive effects are challenging. Therefore, ideal dressings for chronic diabetic wound management must concurrently reduce excessive oxidative stress, promote angiogenesis, and have anti-inflammatory effects. Methods: In this study, Ce-doped borosilicate bioactive glasses (BGs) were prepared using the sol-gel method, and CeO2 nanocrystals (CeO2-NCs) were precipitated on the glass surface by heat treatment to obtain BG-xCe composite glass nanospheres. Subsequently, nanospheres were modified by amino group and combined with dopamine and acrylamide to obtain BG-xCe/polydopamine/polyacrylamide (PDA/PAM) composite hydrogel. Then, the morphology and properties of composite hydrogels were detected, and the properties to treat the diabetic wounds were also evaluated. Results: The results demonstrated that the BG-10Ce/PDA/PAM composite hydrogel possessed excellent tensile and adhesive properties. In vitro, the migration and angiogenesis of human umbilical vein endothelial cells (HUVECs) and fibroblasts (L929) were enhanced by reducing reactive oxygen species (ROS) levels in the conditioned medium. Animal experiments have shown that CeO2-NCs in hydrogels effectively scavenge ROS in diabetic wounds, and Sr dissolved from the glassy phase can modulate macrophage polarization to the M2 phenotype. Conclusions: The synergistic effect of both amorphous materials and nanocrystals provides the BG-10Ce/PDA/PAM composite hydrogel with great potential for diabetic wound healing.

Versatile conductive hydrogel orchestrating neuro-immune microenvironment for rapid diabetic wound healing through peripheral nerve regeneration

Diabetic wound (DW), notorious for prolonged healing processes due to the unregulated immune response, neuropathy, and persistent infection, poses a significant challenge to clinical management. Current strategies for treating DW primarily focus on alleviating the inflammatory milieu or promoting angiogenesis, while limited attention has been given to modulating the neuro-immune microenvironment. Thus, we present an electrically conductive hydrogel dressing and identify its neurogenesis influence in a nerve injury animal model initially by encouraging the proliferation and migration of Schwann cells. Further, endowed with the synergizing effect of near-infrared responsive release of curcumin and nature-inspired artificial heterogeneous melanin nanoparticles, it can harmonize the immune microenvironment by restoring the macrophage phenotype and scavenging excessive reactive oxygen species. This in-situ formed hydrogel also exhibits mild photothermal therapy antibacterial efficacy. In the infected DW model, this hydrogel effectively supports nerve regeneration and mitigates the immune microenvironment, thereby expediting the healing progress. The versatile hydrogel exhibits significant therapeutic potential for application in DW healing through fine-tuning the neuro-immune microenvironment.

Multifunctional combined drug-loaded nanofibrous dressings with anti-inflammatory, antioxidant stress and microenvironment improvement for diabetic wounds

The treatment of diabetic wounds remains a formidable clinical challenge worldwide. Because of persistent inflammatory reaction, excessive oxidative stress, cell dysfunction, poor blood microcirculation and other microvascular complications, diabetic wounds often fall into inflammatory circulation and are difficult to heal, making patients confront the risk of amputation. In this study, silver complex nanoparticles with Resina Draconis extract and Rhodiola rosea L. extract were loaded in situ onto thermoplastic polyurethane nanofibers to develop a multifunctional electrospun nanofiber wound dressing with excellent mechanical properties, superior water absorption and breathability, good coagulation promoting activity, strong antibacterial performance and antioxidant properties. This wound dressing could effectively enhance the migration and proliferation of fibroblasts, reduce the increased thickness of regenerated epidermis caused by diabetes, and the high expression and high lipid peroxidation levels of IL-1 β, IL-6, TNF α, iNOS and MMP-9, and raise the low expression of VEGF, which shows great potential to accelerate the wound healing of diabetic mouse models. The wound healing rate reached about 87.92%, close to the non-diabetic group. Our findings suggest a breakthrough in diabetic wound care, offering a viable solution to a long-standing medical shackle.

Single-cell RNA-seq in diabetic foot ulcer wound healing

Diabetic foot ulcer (DFU) is a chronic and serious complication of diabetes mellitus. It is mainly caused by hyperglycaemia, diabetic peripheral vasculopathy and diabetic peripheral neuropathy. These conditions result in ulceration of foot tissues and chronic wounds. If left untreated, DFU can lead to amputation or even endanger the patient's life. Single-cell RNA sequencing (scRNA-seq) is a technique used to identify and characterise transcriptional subpopulations at the single-cell level. It provides insight into cellular function and the molecular drivers of disease. The objective of this paper is to examine the subpopulations, genes and molecules of cells associated with chronic wounds of diabetic foot by using scRNA-seq. The paper aims to explore the wound-healing mechanism of DFU from three aspects: inflammation, angiogenesis and extracellular matrix remodelling. The goal is to gain a better understanding of the mechanism of DFU wound healing and identify possible DFU therapeutic targets, providing new insights for the application of DFU personalised therapy.

Hyaluronic Acid/Gelatin-Based Multifunctional Bioadhesive Hydrogel Loaded with a Broad-Spectrum Bacteriocin for Enhancing Diabetic Wound Healing

The development of multifunctional wound adhesives is critical in clinical settings due to the scarcity of dressings with effective adhesive properties while protecting against infection by drug-resistant bacteria. Polysaccharide and gelatin-based hydrogels, known for their biocompatibility and bioactivity, assist in wound healing. This study introduces a multifunctional bioadhesive hydrogel developed through dynamic covalent bonding and light-triggered covalent bonding, comprising oxidized hyaluronic acid, methacrylated gelatin, and the bacteriocin recently discovered by our lab, named jileicin (JC). The adhesion strength of the hydrogel, measured at 180 kPa, was 4.35 times higher than that of the fibrin glue. Furthermore, the hydrogel demonstrated robust platelet adhesion, procoagulant activity, and outstanding hemostatic properties in a mouse liver injury model. Incorporating JC significantly enhanced the phagocytosis and bactericidal capabilities of the macrophages. This immunomodulatory function on host cells, coupled with its potent bacterial membrane-disrupting ability, makes JC an effective killer against methicillin-resistant Staphylococcus aureus. In wound repair experiments on diabetic mice with infected full-thickness skin defects, the hydrogel treatment group showed a notable reduction in bacterial load, accelerated M2-type macrophage polarization, diminished inflammation, and hastened wound healing. Owing to its outstanding biocompatibility, antibacterial activity, and controlled adhesion, this hydrogel presents a promising therapeutic option for treating infected skin wounds.

Triple threat: how diabetes results in worsened bacterial infections

Diabetes mellitus, characterized by impaired insulin signaling, is associated with increased incidence and severity of infections. Various diabetes-related complications contribute to exacerbated bacterial infections, including hyperglycemia, innate immune cell dysfunction, and infection with antibiotic-resistant bacterial strains. One defining symptom of diabetes is hyperglycemia, resulting in elevated blood and tissue glucose concentrations. Glucose is the preferred carbon source of several bacterial pathogens, and hyperglycemia escalates bacterial growth and virulence. Hyperglycemia promotes specific mechanisms of bacterial virulence known to contribute to infection chronicity, including tissue adherence and biofilm formation. Foot infections are a significant source of morbidity in individuals with diabetes and consist of biofilm-associated polymicrobial communities. Bacteria perform complex interspecies behaviors conducive to their growth and virulence within biofilms, including metabolic cross-feeding and altered phenotypes more tolerant to antibiotic therapeutics. Moreover, the metabolic dysfunction caused by diabetes compromises immune cell function, resulting in immune suppression. Impaired insulin signaling induces aberrations in phagocytic cells, which are crucial mediators for controlling and resolving bacterial infections. These aberrancies encompass altered cytokine profiles, the migratory and chemotactic mechanisms of neutrophils, and the metabolic reprogramming required for the oxidative burst and subsequent generation of bactericidal free radicals. Furthermore, the immune suppression caused by diabetes and the polymicrobial nature of the diabetic infection microenvironment may promote the emergence of novel strains of multidrug-resistant bacterial pathogens. This review focuses on the "triple threat" linked to worsened bacterial infections in individuals with diabetes: (i) altered nutritional availability in diabetic tissues, (ii) diabetes-associated immune suppression, and (iii) antibiotic treatment failure.

The role of SLC7A11 in diabetic wound healing: novel insights and new therapeutic strategies

Diabetic wounds are a severe complication of diabetes, characterized by persistent, non-healing ulcers due to disrupted wound-healing mechanisms in a hyperglycemic environment. Key factors in the pathogenesis of these chronic wounds include unresolved inflammation and antioxidant defense imbalances. The cystine/glutamate antiporter SLC7A11 (xCT) is crucial for cystine import, glutathione production, and antioxidant protection, positioning it as a vital regulator of diabetic wound healing. Recent studies underscore the role of SLC7A11 in modulating immune responses and oxidative stress in diabetic wounds. Moreover, SLC7A11 influences critical processes such as insulin secretion and the mTOR signaling pathway, both of which are implicated in delayed wound healing. This review explores the mechanisms regulating SLC7A11 and its impact on immune response, antioxidant defenses, insulin secretion, and mTOR pathways in diabetic wounds. Additionally, we highlight the current advancements in targeting SLC7A11 for treating related diseases and conceptualize its potential applications and value in diabetic wound treatment strategies, along with the challenges encountered in this context.

Advances and applications of biomimetic biomaterials for endogenous skin regeneration

Endogenous regeneration is becoming an increasingly important strategy for wound healing as it facilitates skin's own regenerative potential for self-healing, thereby avoiding the risks of immune rejection and exogenous infection. However, currently applied biomaterials for inducing endogenous skin regeneration are simplistic in their structure and function, lacking the ability to accurately mimic the intricate tissue structure and regulate the disordered microenvironment. Novel biomimetic biomaterials with precise structure, chemical composition, and biophysical properties offer a promising avenue for achieving perfect endogenous skin regeneration. Here, we outline the recent advances in biomimetic materials induced endogenous skin regeneration from the aspects of structural and functional mimicry, physiological process regulation, and biophysical property design. Furthermore, novel techniques including in situ reprograming, flexible electronic skin, artificial intelligence, single-cell sequencing, and spatial transcriptomics, which have potential to contribute to the development of biomimetic biomaterials are highlighted. Finally, the prospects and challenges of further research and application of biomimetic biomaterials are discussed. This review provides reference to address the clinical problems of rapid and high-quality skin regeneration.

A Living Microecological Hydrogel with Microbiota Remodeling and Immune Reinstatement for Diabetic Wound Healing

Dysregulated skin microbiota and compromised immune responses are the major etiological factors for non-healing diabetic wounds. Current antibacterial strategies fail to orchestrate immune responses and indiscriminately eradicate bacteria at the wound site, exacerbating the imbalance of microbiota. Drawing inspiration from the beneficial impacts that probiotics possess on microbiota, a living microecological hydrogel containing Lactobacillus plantarum and fructooligosaccharide (LP/FOS@Gel) is formulated to remodel dysregulated skin microbiota and reinstate compromised immune responses, cultivating a conducive environment for optimal wound healing. LP/FOS@Gel acts as an "evocator," skillfully integrating the skin microecology, promoting the proliferation of Lactobacillus, Ralstonia, Muribaculum, Bacillus, and Allobaculum, while eradicating colonized pathogenic bacteria. Concurrently, LP/FOS@Gel continuously generates lactic acid to elicit a reparative macrophage response and impede the activation of the nuclear factor kappa-B pathway, effectively alleviating inflammation. As an intelligent microecological system, LP/FOS@Gel reinstates the skin's sovereignty during the healing process and effectively orchestrates the harmonious dialogue between the host immune system and microorganisms, thereby fostering the healing of diabetic infectious wounds. These remarkable attributes render LP/FOS@Gel highly advantageous for pragmatic clinical applications.

Vascular endothelial growth factor accelerates healing of foot ulcers in diabetic rats via promoting M2 macrophage polarization

AIM

The objective was to investigate the specific role and the regulatory mechanism of vascular endothelial growth factor (VEGF) during wound healing in diabetic foot ulcer (DFU).

METHODS

Streptozotocin-induced diabetic rats were used to establish a DFU animal model. VEGF and Axitinib (a specific inhibitor of VEGFR) were used for treatment in vivo. The wounds at different time points were imaged and histological analysis of the wounds were performed by haematoxylin and eosin (H&E) staining and Masson's trichrome staining. Immunohistochemical staining was conducted to examine CD31 and eNOS expression in the wounds. Immunofluorescence assay and quantitative real-time PCR were performed to examine macrophage markers. In addition, THP-1 was differentiated to macrophages, and then treated with interleukin (IL)-4 to induce M2 macrophages, followed by VEGF treatment. The conditional medium (CM) from VEGF-mediated macrophages were collected to culture human dermal fibroblasts (HDFs). Cell viability and migration were measured by Cell Counting Kit (CCK)-8, wound-healing and Transwell assays, respectively.

RESULTS

VEGF treatment remarkably accelerated wound healing of DFU rats. VEGF promoted collagen deposition and elevated CD31 and eNOS expression, confirming the pro-angiogenesis of VEGF around diabetic wound in rats. Meanwhile, VEGF restricted pro-inflammatory cytokines and increased F4/80 and CD206 expression, highlighting the activated macrophages and enhanced M2 macrophages following VEGF treatment in diabetic wounds of DFU rats. However, Axitinib exerted an opposite function to VEGF in DFU rats. Moreover, VEGF directly promoted macrophage polarization toward M2 phenotype in vitro, and the CM from VEGF-mediated M2 macrophages markedly promoted HDFs proliferation, migration and collagen deposition.

CONCLUSION

VEGF might accelerate the wound healing of DFU through promoting M2 macrophage polarization and fibroblast migration.

Single-Cell RNA Sequencing Reveals a Unique Fibroblastic Subset and Immune Disorder in Lichen Sclerosus Urethral Stricture

Purpose

Lichen sclerosus urethral stricture disease (LS USD) is a refractory and progressive disease primarily affecting the anterior urethra in males. Various potential etiological factors, such as genetics, autoimmunity, infection, and exposure to infectious urine, have been suggested. However, the accurate etiology of LS in the male urethra remains unclear.

Patients and Methods

In this study, we conducted single-cell RNA sequencing to identify the transcriptional profiles of three patients with LS USD and three patients with non-LS USD. Immunofluorescence was used to confirm the single-cell sequence results.

Results

Our study revealed distinct subsets of vein endothelial cells (ECs), smooth muscle cells (SMCs), and fibroblasts (FBs) with high proportions in LS USD, contributing to the tissue microenvironment primarily involved in proinflammatory and immune responses. In particular, FBs displayed a unique subset, Fib7, which is exclusively present in LS USD, and exhibited high expression levels of SAA1 and SAA2. The accumulation of macrophages, along with the dysregulated ratios of M1/M2-like phenotype macrophages, may be engaged in the pathogenesis of LS USD. Through cell-cell communication analysis, we identified significant interactions involving CXCL8/ACKR1 and CCR7/CCL19 in LS USD. Remarkably, Fib7 exhibited exclusive communication with IL-1B macrophages through the SAA1/FPR2 receptor-ligand pair.

Conclusion

Our study provides a profound understanding of the tissue microenvironment in LS USD, which may be valuable for understanding the pathogenesis of LS USD.

Transcriptional analysis of efferocytosis in mouse skin wounds

Defects in apoptotic cell clearance, or efferocytosis, can cause inflammatory diseases and prevent tissue repair due in part to inducing a pro-repair transcriptional program in phagocytic cells like macrophages. While the cellular machinery and metabolic pathways involved in efferocytosis have been characterized, the precise efferocytic response of macrophages is dependent on the identity and macromolecular cues of apoptotic cells, and the complex tissue microenvironment in which efferocytosis occurs. Here, we find that macrophages undergoing active efferocytosis in mid-stage mouse skin wounds in vivo display a pro-repair gene program, while efferocytosis of apoptotic skin fibroblasts in vitro also induces an inflammatory transcription response. These data provide a resource for understanding how the skin wound environment influences macrophage efferocytosis and will be useful for future investigations that define the role of efferocytosis during tissue repair.

Therapeutic implication of targeting mitochondrial drugs designed for efferocytosis dysfunction

Efferocytosis refers to the process by which phagocytes remove apoptotic cells and related apoptotic products. It is essential for the growth and development of the body, the repair of damaged or inflamed tissues, and the balance of the immune system. Damaged efferocytosis will cause a variety of chronic inflammation and immune system diseases. Many studies show that efferocytosis is a process mediated by mitochondria. Mitochondrial metabolism, mitochondrial dynamics, and communication between mitochondria and other organelles can all affect phagocytes' clearance of apoptotic cells. Therefore, targeting mitochondria to modulate phagocyte efferocytosis is an anticipated strategy to prevent and treat chronic inflammatory diseases and autoimmune diseases. In this review, we introduced the mechanism of efferocytosis and the pivoted role of mitochondria in efferocytosis. In addition, we focused on the therapeutic implication of drugs targeting mitochondria in diseases related to efferocytosis dysfunction.

Hypoxic microenvironment promotes diabetic wound healing by polarizing macrophages to the M2 phenotype in vivo

BACKGROUND

In diabetic wounds, M2 polarization of macrophages regulates the transition from an inflammatory phase to a proliferative phase. Prior investigations have demonstrated the potential of deferoxamine (DFO) in creating a localized hypoxic microenvironment, which could stimulate angiogenesis by promoting vascular endothelial growth factor (VEGF) secretion in diabetic wound healing. Nevertheless, there is still no clear information on whether this chemically induced hypoxic microenvironment modulates macrophage polarization to promote diabetic wound healing.

METHODS

The 18 diabetic mice were randomly divided into three groups: a control group (n = 6), a 100µM DFO group (n = 6), and a 200µM DFO group (n = 6). Subsequently, a full-thickness wound with a diameter of 1.00 cm was created on the dorsal region of the diabetic mice. Observe wound closure regularly during treatment. At the end of the observation, tissue specimens were collected for a series of experiments and analyses, including hematoxylin and eosin (H&E), Masson, immunofluorescent, and immunohistochemical staining. The role and mechanism of DFO in regulating macrophage polarization were studied using RAW264.7 cells.

RESULTS

In comparison to the control group, the administration of DFO notably facilitates wound healing in diabetic mice. In diabetic wounds, DFO increases blood supply by upregulating VEGF, which promotes angiogenesis. Additionally, The expression of HSP70 and CD206 were also upregulated by DFO in both vivo and in vitro, while iNOS expression was downregulated. Additionally, knk437 inhibited the expression of HSP70 in RAW264.7 cells, resulting in a reduction of M2 polarization and an increase in M1 polarization.

CONCLUSION

The induction of a hypoxic microenvironment by DFO has been found to exert a substantial influence on the process of diabetic wound healing. DFO treatment enhances the capacity of diabetic wounds to stimulate angiogenesis and modulate macrophage polarization that may be associated with HSP70 expression, thereby expediting the transition of these wounds from an inflammatory to a proliferative state.

Tracing Immunological Interaction in Trimethylamine N-Oxide Hydrogel-Derived Zwitterionic Microenvironment During Promoted Diabetic Wound Regeneration

The diabetic wound healing is challenging due to the sabotaged delicate balance of immune regulation via an undetermined pathophysiological mechanism, so it is crucial to decipher multicellular signatures underlying diabetic wound healing and seek therapeutic strategies. Here, this work develops a strategy using novel trimethylamine N-oxide (TMAO)-derived zwitterionic hydrogel to promote diabetic wound healing, and explore the multi-cellular ecosystem around zwitterionic hydrogel, mapping out an overview of different cells in the zwitterionic microenvironment by single-cell RNA sequencing. The diverse cellular heterogeneity is revealed, highlighting the critical role of macrophage and neutrophils in managing diabetic wound healing. It is found that polyzwitterionic hydrogel can upregulate Ccl3+ macrophages and downregulate S100a9+ neutrophils and facilitate their interactions compared with polyanionic and polycationic hydrogels, validating the underlying effect of zwitterionic microenvironment on the activation of adaptive immune system. Moreover, zwitterionic hydrogel inhibits the formation of neutrophil extracellular traps (NETs) and promotes angiogenesis, thus improving diabetic wound healing. These findings expand the horizons of the sophisticated orchestration of immune systems in zwitterion-directed diabetic wound repair and uncover new strategies of novel immunoregulatory biomaterials.

Macrophage plasticity: signaling pathways, tissue repair, and regeneration

Macrophages are versatile immune cells with remarkable plasticity, enabling them to adapt to diverse tissue microenvironments and perform various functions. Traditionally categorized into classically activated (M1) and alternatively activated (M2) phenotypes, recent advances have revealed a spectrum of macrophage activation states that extend beyond this dichotomy. The complex interplay of signaling pathways, transcriptional regulators, and epigenetic modifications orchestrates macrophage polarization, allowing them to respond to various stimuli dynamically. Here, we provide a comprehensive overview of the signaling cascades governing macrophage plasticity, focusing on the roles of Toll-like receptors, signal transducer and activator of transcription proteins, nuclear receptors, and microRNAs. We also discuss the emerging concepts of macrophage metabolic reprogramming and trained immunity, contributing to their functional adaptability. Macrophage plasticity plays a pivotal role in tissue repair and regeneration, with macrophages coordinating inflammation, angiogenesis, and matrix remodeling to restore tissue homeostasis. By harnessing the potential of macrophage plasticity, novel therapeutic strategies targeting macrophage polarization could be developed for various diseases, including chronic wounds, fibrotic disorders, and inflammatory conditions. Ultimately, a deeper understanding of the molecular mechanisms underpinning macrophage plasticity will pave the way for innovative regenerative medicine and tissue engineering approaches.

Tropoelastin modulates systemic and local tissue responses to enhance wound healing

Wound healing is facilitated by biomaterials-based grafts and substantially impacted by orchestrated inflammatory responses that are essential to the normal repair process. Tropoelastin (TE) based materials are known to shorten the period for wound repair but the mechanism of anti-inflammatory performance is not known. To explore this, we compared the performance of the gold standard Integra Dermal Regeneration Template (Integra), polyglycerol sebacate (PGS), and TE blended with PGS, in a murine full-thickness cutaneous wound healing study. Systemically, blending with TE favorably increased the F4/80+ macrophage population by day 7 in the spleen and contemporaneously induced elevated plasma levels of anti-inflammatory IL-10. In contrast, the PGS graft without TE prompted prolonged inflammation, as evidenced by splenomegaly and greater splenic granulocyte and monocyte fractions at day 14. Locally, the inclusion of TE in the graft led to increased anti-inflammatory M2 macrophages and CD4+T cells at the wound site, and a rise in Foxp3+ regulatory T cells in the wound bed by day 7. We conclude that the TE-incorporated skin graft delivers a pro-healing environment by modulating systemic and local tissue responses. STATEMENT OF SIGNIFICANCE: Tropoelastin (TE) has shown significant benefits in promoting the repair and regeneration of damaged human tissues. In this study, we show that TE promotes an anti-inflammatory environment that facilitates cutaneous wound healing. In a mouse model, we find that inserting a TE-containing material into a full-thickness wound results in defined, pro-healing local and systemic tissue responses. These findings advance our understanding of TE's restorative value in tissue engineering and regenerative medicine, and pave the way for clinical applications.

Bioengineered mesenchymal stem cell-derived exosomes: emerging strategies for diabetic wound healing

Diabetic wounds are among the most common complications of diabetes mellitus and their healing process can be delayed due to persistent inflammatory reactions, bacterial infections, damaged vascularization and impaired cell proliferation, which casts a blight on patients'health and quality of life. Therefore, new strategies to accelerate diabetic wound healing are being positively explored. Exosomes derived from mesenchymal stem cells (MSC-Exos) can inherit the therapeutic and reparative abilities of stem cells and play a crucial role in diabetic wound healing. However, poor targeting, low concentrations of therapeutic molecules, easy removal from wounds and limited yield of MSC-Exos are challenging for clinical applications. Bioengineering techniques have recently gained attention for their ability to enhance the efficacy and yield of MSC-Exos. In this review, we summarise the role of MSC-Exos in diabetic wound healing and focus on three bioengineering strategies, namely, parental MSC-Exos engineering, direct MSC-Exos engineering and MSC-Exos combined with biomaterials. Furthermore, the application of bioengineered MSC-Exos in diabetic wound healing is reviewed. Finally, we discuss the future prospects of bioengineered MSC-Exos, providing new insights into the exploration of therapeutic strategies.

Global trends in publications regarding macrophages-related diabetic foot ulcers in the last two decades

BACKGROUND

Diabetic foot ulcers (DFUs) are one of the most severe and popular complications of diabetes. The persistent non-healing of DFUs is the leading cause of ampu-tation, which causes significant mental and financial stress to patients and their families. Macrophages are critical cells in wound healing and perform essential roles in all phases of wound healing. However, no studies have been carried out to systematically illustrate this area from a scientometric point of view. Although there have been some bibliometric studies on diabetes, reports focusing on the investigation of macrophages in DFUs are lacking.

AIM

To perform a bibliometric analysis to systematically assess the current state of research on macrophage-related DFUs.

METHODS

The publications of macrophage-related DFUs from January 1, 2004, to December 31, 2023, were retrieved from the Web of Science Core Collection on January 9, 2024. Four different analytical tools: VOSviewer (v1.6.19), CiteSpace (v6.2.R4), HistCite (v12.03.07), and Excel 2021 were used for the scientometric research.

RESULTS

A total of 330 articles on macrophage-related DFUs were retrieved. The most published countries, institutions, journals, and authors in this field were China, Shanghai Jiao Tong University of China, Wound Repair and Regeneration, and Aristidis Veves. Through the analysis of keyword co-occurrence networks, historical direct citation networks, thematic maps, and trend topics maps, we synthesized the prevailing research hotspots and emerging trends in this field.

CONCLUSION

Our bibliometric analysis provides a comprehensive overview of macrophage-related DFUs research and insights into promising upcoming research.

Periplaneta americana extract promotes infectious diabetic ulcers wound healing by downregulation of LINC01133/SLAMF9

Wound healing in diabetic ulcers remains a significant clinical challenge, primarily due to bacterial infection and impaired angiogenesis. Periplaneta americana extract (PAE) has been widely used to treat diabetic wounds, yet its underlying mechanisms are not fully understood. This study aimed to elucidate these mechanisms by analyzing long non-coding RNA (lncRNA) expressions in the wound tissues from diabetic anal fistula patients treated with or without PAE, using high-throughput sequencing. Peripheral blood monocytes from patients were differentiated into M0 macrophages with human macrophage colony-stimulating factor (hM-CSF) and subsequently polarized into M1 macrophages with lipopolysaccharide. The results indicated that LINC01133 and SLAMF9 were downregulated in wound tissues of patients treated with PAE. Furthermore, PAE suppressed M1 macrophage polarization and enhanced human umbilical vein endothelial cell (HUVEC) proliferation, migration, and angiogenesis. These effects were diminished when LINC01133 or SLAMF9 were overexpressed. Mechanistically, LINC01133 was shown to upregulate SLAMF9 through interaction with ELAVL1. Overexpression of SLAMF9 reversed the effects of LINC01133 silencing on macrophage polarization and HUVEC functions. In conclusion, PAE facilitates the healing of infected diabetic ulcers by downregulating the LINC01133/SLAMF9 pathway.

The Mechanisms of Adipose Stem Cell-Derived Exosomes Promote Wound Healing and Regeneration

Chronic wound healing is a class of diseases influenced by multiple complex factors, causing severe psychological and physiological impact on patients. It is an intractable clinical challenge and its possible mechanisms are not yet clear. It has been proven that adipose stem cell-derived exosomes (ADSC-Exos) can promote wound healing and inhibit scar formation by regulating inflammation, promoting cell proliferation, migration, and angiogenesis, regulating matrix remodeling, which provides a new approach for wound healing through biological treatment. This review focuses on the mechanism, treatment, and administration methods of ADSC-Exos in wound healing, providing a comprehensive understanding the mechanisms of ADSC-Exos on wound healing. LEVEL OF EVIDENCE I: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

G-protein-coupled receptor 84 regulates acute inflammation in normal and diabetic skin wounds

Lipids have emerged as potent regulators of immune cell function. In the skin, adipocyte lipolysis increases the local pool of free fatty acids and is essential for coordinating early macrophage inflammation following injury. Here, we investigate G-protein-coupled receptor 84 (GPR84), a medium-chain fatty acid (MCFA) receptor, for its potential to propagate pro-inflammatory signaling after skin injury. GPR84 signaling was identified as a key component of regulating myeloid cell numbers and subsequent tissue repair through in vivo administration of a pharmacological antagonist and the MCFA decanoic acid. We found that impaired injury-induced dermal adipocyte lipolysis is a hallmark of diabetes, and lipidomic analysis demonstrated that MCFAs are significantly reduced in diabetic murine wounds. Furthermore, local administration of decanoic acid rescued myeloid cell numbers and tissue repair during diabetic wound healing. Thus, GPR84 is a readily targetable lipid signaling pathway for manipulating injury-induced tissue inflammation with beneficial effects on acute diabetic healing.

Adipose-Derived Stem Cell Exosomes Facilitate Diabetic Wound Healing: Mechanisms and Potential Applications

Wound healing in diabetic patients is frequently hampered. Adipose-derived stem cell exosomes (ADSC-eoxs), serving as a crucial mode of intercellular communication, exhibit promising therapeutic roles in facilitating wound healing. This review aims to comprehensively outline the molecular mechanisms through which ADSC-eoxs enhance diabetic wound healing. We emphasize the biologically active molecules released by these exosomes and their involvement in signaling pathways associated with inflammation modulation, cellular proliferation, vascular neogenesis, and other pertinent processes. Additionally, the clinical application prospects of the reported ADSC-eoxs are also deliberated. A thorough understanding of these molecular mechanisms and potential applications is anticipated to furnish a theoretical groundwork for combating diabetic wound healing.

Antibacterial Antimicrobial Peptide Grafted HA/SF/Alg Wound Dressing Containing AIEgens for Infected Wound Treating

Chronic wounds are characterized with excessive biofluid and persistent infection. Therefore, there is an urgent desire to develop a multifunctional wound dressing that can meet the extreme requirements including effective antibacterial and powerful wound microenvironment regulation and protection function to promote wounds heal quickly. In this study, a multifunctional composite dressing (HA-AMP/SF/Alg/Rb-BG-AIEgens) was synthesized by combining a mesoporous bioactive glass framework loaded with AIEgens (Rb-BG-AIEgens) with cross-linked antimicrobial peptide grafted hyaluronic acid (HA-AMP), sodium alginate (Alg), and silk fibroin (SF). It is important to note that the Rb-BG-AIEgens can achieve real-time and sensitive bacterial detection. HA-AMP can achieve broad spectrum antibacterial and avoid the residue of drug-resistant bacteria. The HA-AMP/SF/Alg/Rb-BG-AIEgens dressing can up-regulate related proliferative proteins, thereby promoting regeneration of tissue and the rapid healing of chronic wounds. With good biocompatibility and antibacterial ability, HA-AMP/SF/Alg/Rb-BG-AIEgens dressing has great potential to become a next generation wound dressing for clinical biological fluid management and chronic bacterial infection treatment.

Enhancing diabetic wound healing with a pH/glucose dual-responsive hydrogel for ROS clearance and antibacterial activity

Currently, the treatment of diabetic wounds in clinical practice is still unsatisfactory due to the risks of oxidative damage and bacterial infection during the healing process. An optimal wound dressing should exhibit robust capabilities in scavenging reactive oxygen species (ROS) and combatting bacterial growth. In this study, we utilized borax as a crosslinker and prepared a pH/glucose dual-responsive composite hydrogel based on poly(vinyl alcohol) (PVA), sodium alginate (SA), and tannic acid (TA). This hydrogel, loaded with cerium dioxide, serves as an effective ROS scavenger, promoting wound closure by reducing the level of ROS in the wound area. Additionally, the hydrogel can release the antibacterial drug ofloxacin in response to the low pH and high glucose microenvironment in infected wounds. Results from skin defect model in diabetic mice demonstrated this ROS-scavenging and antibacterial hydrogel can suppress inflammation and accelerate wound healing. In summary, our work provides a new perspective on a local and stimulus-responsive drug delivery strategy for treating diabetic wounds.

Exosomes from adipose-derived stem cells regulate macrophage polarization and accelerate diabetic wound healing via the circ-Rps5/miR-124-3p axis

BACKGROUND

Adipose-derived stem cells (ADSCs) hold promising application prospects in the treatment of diabetic wounds, although the underlying mechanisms of repair have not been fully elucidated. This research aimed to elucidate the mechanisms by which ADSCs promote wound healing.

METHODS

Exosomes from ADSCs were isolated and circRps5 level was identified. To investigate the role of circRps5 in the regulation, exosomes from differently treated ADSCs were used. Different exosomes were injected into the edge of the wound in diabetic mice, and the effects on wound healing status, pathology, collagen, cytokines, and macrophage phenotype were assessed. Raw264.7 cells were co-treated with high glucose and exosomes, and then cell phenotype and autophagy were examined in vitro, followed by the evaluation of miR-124-3p's impact on cell phenotype.

RESULTS

Exosomes from ADSCs were isolated and identified using nanoparticle tracking analysis and exosome markers. Overexpression of circRps5 accelerated wound healing, reduced inflammatory response, enhanced collagen production, and promoted the M2 transformation of macrophages. In high glucose-induced macrophages, its overexpression also inhibited excessive autophagy. When macrophages overexpressed miR-124-3p, the induction of the M2 phenotype was suppressed. Luciferase reporter assay proved the combination of circRps5 and miR-124-3p.

CONCLUSION

This study identifies that circRps5 carried by ADSC-Exos promotes macrophage M2 polarization through miR-124-3p. These findings provide valuable insights into the mechanism of ADSC-Exos for treating refractory diabetic wounds, laying a solid theoretical groundwork for future clinical development.

IL-17 Control of Cutaneous Immune Homeostasis

IL-17 is widely recognized for its roles in host defense and inflammatory disorders. However, it has become clear that IL-17 is also an essential regulator of barrier tissue physiology. Steady-state microbe sensing at the skin surface induces low-level IL-17 expression that enhances epithelial integrity and resists pathogens without causing overt inflammation. Recent reports describe novel protective roles for IL-17 in wound healing and counteracting physiologic stress; however, chronic amplification of these beneficial responses contributes to skin pathologies as diverse as fibrosis, cancer, and autoinflammation. In this paper, we discuss the context-specific roles of IL-17 in skin health and disease and therapeutic opportunities.

Efferocytosis: Unveiling its potential in autoimmune disease and treatment strategies

Efferocytosis is a crucial process whereby phagocytes engulf and eliminate apoptotic cells (ACs). This intricate process can be categorized into four steps: (1) ACs release "find me" signals to attract phagocytes, (2) phagocytosis is directed by "eat me" signals emitted by ACs, (3) phagocytes engulf and internalize ACs, and (4) degradation of ACs occurs. Maintaining immune homeostasis heavily relies on the efficient clearance of ACs, which eliminates self-antigens and facilitates the generation of anti-inflammatory and immunosuppressive signals that maintain immune tolerance. However, any disruptions occurring at any of the efferocytosis steps during apoptosis can lead to a diminished efficacy in removing apoptotic cells. Factors contributing to this inefficiency encompass dysregulation in the release and recognition of "find me" or "eat me" signals, defects in phagocyte surface receptors, bridging molecules, and other signaling pathways. The inadequate clearance of ACs can result in their rupture and subsequent release of self-antigens, thereby promoting immune responses and precipitating the onset of autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes, and multiple sclerosis. A comprehensive understanding of the efferocytosis process and its implications can provide valuable insights for developing novel therapeutic strategies that target this process to prevent or treat autoimmune diseases.

Promoting Diabetic Wound Healing through a Hydrogel-Based Cascade Regulation Strategy of Fibroblast-Macrophage

The management of diabetic wounds (DWs) continues to pose a significant challenge in the field of medicine. DWs are primarily prevented from healing due to damage to macrophage efferocytosis and fibroblast dysfunction. Consequently, a treatment strategy that involves both immunoregulation and the promotion of extracellular matrix (ECM) formation holds promise for healing DWs. Nevertheless, existing treatment methods necessitate complex interventions and are associated with increased costs, for example, the use of cytokines and cell therapy, both of which have limited effectiveness. In this study, a new type of ruthenium (IV) oxide nanoparticles (RNPs)-laden hybrid hydrogel dressing with a double network of Pluronic F127 and F68 has been developed. Notably, the hybrid hydrogel demonstrates remarkable thermosensitivity, injectability, immunoregulatory characteristics, and healing capability. RNPs in hydrogel effectively regulate both fibroblasts and macrophages in a cascade manner, stimulating fibroblast differentiation while synergistically enhancing the efferocytosis of macrophage. The immunoregulatory character of the hydrogel aids in restoring the intrinsic stability of the immune microenvironment in the wound and facilitates essential remodeling of the ECM. This hydrogel therefore offers a novel approach for treating DWs through intercellular communication.

A pro-reparative bioelectronic device for controlled delivery of ions and biomolecules

Wound healing is a complex physiological process that requires precise control and modulation of many parameters. Therapeutic ion and biomolecule delivery has the capability to regulate the wound healing process beneficially. However, achieving controlled delivery through a compact device with the ability to deliver multiple therapeutic species can be a challenge. Bioelectronic devices have emerged as a promising approach for therapeutic delivery. Here, we present a pro-reparative bioelectronic device designed to deliver ions and biomolecules for wound healing applications. The device incorporates ion pumps for the targeted delivery of H+ and zolmitriptan to the wound site. In vivo studies using a mouse model further validated the device's potential for modulating the wound environment via H+ delivery that decreased M1/M2 macrophage ratios. Overall, this bioelectronic ion pump demonstrates potential for accelerating wound healing via targeted and controlled delivery of therapeutic agents to wounds. Continued optimization and development of this device could not only lead to significant advancements in tissue repair and wound healing strategies but also reveal new physiological information about the dynamic wound environment.

Tissue Regeneration and Remodeling in Rat Models after Application of Hypericum perforatum L. Extract-Loaded Bigels

The wound-healing effect of St. John's Wort (SJW) is mainly attributed to hyperforin (HP), but its low stability restricts its topical administration. This study investigates how "free" HP-rich SJW extract (incorporated into a bigel; B/SJW) and extract "protected" by nanostructured lipid carriers (also included in a biphasic semisolid; B/NLC-SJW) affect tissue regeneration in a rat skin excision wound model. Wound diameter, histological changes, and tissue gene expression levels of fibronectin (Fn), matrix metalloproteinase 8 (MMP8), and tumor necrosis factor-alpha (TNF-α) were employed to quantify the healing progress. A significant wound size reduction was achieved after applying both extract-containing semisolids, but after a 21-day application period, the smallest wound size was observed in the B/NLC-SJW-treated animals. However, the inflammatory response was affected more favorably by the bigel containing the "free" SJW extract, as evidenced by histological studies. Moreover, after the application of B/SJW, the expression of Fn, MMP8, and TNF-α was significantly higher than in the positive control. In conclusion, both bigel formulations exhibited beneficial effects on wound healing in rat skin, but B/SJW affected skin restoration processes in a comprehensive and more efficient way.

Micro-environment triple-responsive hyaluronic acid hydrogel dressings to promote antibacterial activity, collagen deposition, and angiogenesis for diabetic wound healing

The clinical treatment of chronic diabetic wounds is a long-standing thorny issue. Strategies targeting the diabetic micro-environment have been developed to promote wound healing. However, it remains challenging to reverse the adverse conditions and re-activate tissue regeneration and angiogenesis. In this work, we develop injectable hydrogels that are responsive to acidic conditions, reactive oxygen species (ROS), and high glucose levels in a diabetic wound micro-environment to sustainably deliver tannic acid (TA) to augment antibacterial, anti-inflammatory, and anti-oxidative activities. This triple-responsive mechanism is designed by introducing dynamic acylhydrazone and phenylboronic ester bonds to crosslink modified hyaluronic acid (HA) chains. At a diabetic wound, the acylhydrazone bonds may be hydrolyzed at low pH. Meanwhile, glucose may compete with TA, and ROS may oxidize the C-B bond to release TA. Thus, sustained release of TA is triggered by the diabetic micro-environment. The released TA effectively scavenges ROS and kills bacteria. In vivo experiments on diabetic mice demonstrate that the hydrogel dressing highly promotes angiogenesis and extracellular matrix (ECM) deposition, leading to eventual full healing of diabetic skin wounds. This micro-environment-triggered triple-responsive drug release provides a promising method for chronic diabetic wound healing.

Biopolymer based nanoparticles and their therapeutic potential in wound healing - A review

Nanoparticles (NPs) have been extensively investigated for their potential in nanomedicine. There is a significant level of enthusiasm about the potential of NPs to bring out a transformative impact on modern healthcare. NPs can serve as effective wound dressings or delivery vehicles due to their antibacterial and pro-wound-healing properties. Biopolymer-based NPs can be manufactured using various food-grade biopolymers, such as proteins, polysaccharides, and synthetic polymers, each offering distinct properties suitable for different applications which include collagen, polycaprolactone, chitosan, alginate, and polylactic acid, etc. Their biodegradable and biocompatible nature renders them ideal nanomaterials for applications in wound healing. Additionally, the nanofibers containing biopolymer-based NPs have shown excellent anti-bacterial and wound healing activity like silver NPs. These NPs represent a paradigm shift in wound healing therapies, offering targeted and personalized solutions for enhanced tissue regeneration and accelerated wound closure. The current review focuses on biopolymer NPs with their applications in wound healing.

Dysfunctional iron metabolism in pressure injuries is related to aberrant CD163 and Homx-1 signal transduction

Dysregulation of iron metabolism has been associated with impaired chronic wound healing. However, changes in iron metabolism have yet to be reported in pressure injuries, a type of chronic wound. In this study, we aimed to investigate changes in iron metabolism and associated regulatory mechanisms in pressure injuries. We collected tissue biopsies and data from 20 consenting stage IV-pressure injuries patients and 5 non-pressure injuries patients hospitalised at the Affiliated Hospital of Qingdao University between March 2021 and June 2021. In addition, we measured the iron content by inductively coupled plasma mass spectrometry and Prussian blue staining in deep tissue pressure injury mouse models. An Enzyme-linked immune sorbent assay measured the expression of ferritin, ferroportin-1 and transferrin. Immunofluorescence staining, high-throughput transcriptome sequencing, Western blot and RT-qPCR further analysed the fundamental mechanisms regulating iron metabolism. In this study, we observed numerous inflammatory cells infiltrating the marginal tissues of stage IV pressure injury patients and in deep tissue pressure injury models. The expression levels of pro-inflammatory factors, such as inducible nitric oxide synthase and interleukin-6, were significantly increased (p < 0.05). The iron level was proportional to the degree of progression, with the most significant change appearing on the third day in deep tissue pressure injury models (p < 0.05). Enzyme-linked immune sorbent assay results suggested abnormal gene expression was related to iron metabolism, including a substantial increase in ferritin and a significant decrease in the expression of ferroportin-1 (p < 0.05). In addition, immunofluorescence staining and Western blot showed that the expression of macrophage membrane receptor CD163 was abnormally elevated (p < 0.05). Both high-throughput transcriptome sequencing and qRT-PCR results suggested aberrant expression of the CD163/Homx-1-mediated signalling pathway. Dysfunctional iron metabolism was suggested to be related to the aberrant CD163/Homx-1 signalling pathway in deep tissue pressure injury models.

Injectable and Microporous Microgel-Fiber Granular Hydrogel Loaded with Bioglass and siRNA for Promoting Diabetic Wound Healing

Injectable hydrogels find extensive application in the treatment of diabetic wound healing. However, traditional bulk hydrogels are significantly limited due to their nano-porous structure, which obstructs cell migration and tissue infiltration. Moreover, regulating inflammation and matrix metalloproteinase -9 (MMP-9) expression in diabetic wounds is crucial for enhancing wound healing. This study marks the first instance of introducing an efficient, scalable, and simple method for producing microfiber-gel granules encapsulating bioceramics powders. Utilizing this method, an injectable microporous granular microgel-fiber hydrogel (MFgel) is successfully developed by assembling microgel-fibers made from hyaluronic acid (HA) and sodium alginate (SA) loaded with small interfering RNA (siRNA) and bioglass (BG) particles. Compared to traditional hydrogels (Tgel), MFgel possesses a highly interconnected network with micron-sized pores, demonstrating favorable properties for cell adhesion and penetration in in vitro experiments. Additionally, MFgel exhibits a higher compressive modulus and superior mechanical stability. When implanted subcutaneously in mice, MFgel promotes cellular and tissue infiltration, facilitating cell proliferation. Furthermore, when applied to skin defects in diabetic rats, MFgel not only effectively regulates inflammation and suppresses MMP-9 expression but also enhances angiogenesis and collagen deposition, thereby significantly accelerating diabetic wound healing. Taken together, this hydrogel possesses great potential in diabetic wound healing applications.

Uncommon dermatologic manifestation (paronychia) in a cat with diabetes mellitus

A 3.5-year-old male intact domestic short hair cat presented for a chronic wound and crusts over the claw and claw folds over several months. The cat was diagnosed with diabetes mellitus based on the presence of persistent hyperglycemia, glucosuria, and compatible clinical signs which consist of polyuria, polydipsia, polyphagia, and weight loss. Glipizide (Glucotrol XL, Pfizer, Indonesia) 2.5 mg orally twice daily was prescribed. By the seventeenth day, the patient's claws and skin around the paw had normalized and the abnormal claw sloughed off, revealing a normal claw underneath. Blood glucose, urinalysis and serum fructosamine were also normalized by the thirtieth day. The patient underwent diabetic remission, and the skin and claw lesions have remained in remission and not recurred since the treatment of the diabetes mellitus. This is the first report of a diabetic cat with dermatologic changes to the skin and claw regions. As the diabetes mellitus went into clinical remission, so too did the dermatologic manifestations, even without any specific dermatologic treatment.

The mutual regulation between γδ T cells and macrophages during wound healing

Macrophages are the main cells shaping the local microenvironment during wound healing. As the prime T cells in the skin, γδ T cells participate in regulating microenvironment construction, determining their mutual regulation helps to understand the mechanisms of wound healing, and explore innovative therapeutic options for wound repair. This review introduced their respective role in wound healing firstly, and then summarized the regulatory effect of γδ T cells on macrophages, including chemotaxis, polarization, apoptosis, and pyroptosis. Last, the retrograde regulation on γδ T cells by macrophages was also discussed. The main purpose is to excavate novel interventions for treating wound and provide new thought for further research.

The future of diabetic wound healing: unveiling the potential of mesenchymal stem cell and exosomes therapy

Diabetes mellitus (DM) is a significant public health problem and is one of the most challenging medical conditions worldwide. It is the severe complications that make this disease more intricate. A diabetic wound is one of these complications. Patients with diabetes are at higher risk of developing diabetic foot ulcers (DFU). Due to the ineffectiveness of Conventional treatments, growth in limb amputation, morbidity, and mortality have been recognized, which indicates the need for additional treatment. Mesenchymal stem cells (MSCs) can significantly improve wound healing. However, there are some risks related to stem cell therapy. Exosome therapy is a new treatment option for diabetic wounds that has shown promising results. However, an even more advanced form called cell-free therapy using exosomes has emerged. This upgraded version of stem cell therapy offers improved efficacy and eliminates the risk of cancer progression. Exosome therapy promotes wound healing from multiple angles, unlike traditional methods that primarily rely on the body's self-healing ability and only provide wound protection. Therefore, exosome therapy has the potential to replace conventional treatments effectively. However, further research is necessary to distinguish the optimal type of stem cells for therapy, ensure their safety, establish appropriate dosing, and identify the best management trail. The present study focused on the current literature on diabetic wound ulcers, their treatment, and mesenchymal stem cell and exosome therapy potential in DFU.

Spatiotemporal orchestration of macrophage activation trajectories by Vγ4 T cells during skin wound healing

Dysregulated macrophage polarization from pro-inflammatory M1 to anti-inflammatory M2 phenotypes underlies impaired cutaneous wound healing. This study reveals Vγ4+ γδ T cells spatiotemporally calibrate macrophage trajectories during skin repair via sophisticated interferon-γ (IFN-γ) conditioning across multiple interconnected tissues. Locally within wound beds, infiltrating Vγ4+ γδ T cells directly potentiate M1 activation and suppress M2 polarization thereby prolonging local inflammation. In draining lymph nodes, infiltrated Vγ4+ γδ T cells expand populations of IFN-γ-competent lymphocytes which disseminate systemically and infiltrate into wound tissues, further enforcing M1 macrophages programming. Moreover, Vγ4+γδ T cells flushed into bone marrow stimulate increased IFN-γ production, which elevates the output of pro-inflammatory Ly6C+monocytes. Mobilization of these monocytes continually replenishes the M1 macrophage pool in wounds, preventing phenotypic conversion to M2 activation. Thus, multi-axis coordination of macrophage activation trajectories by trafficking Vγ4+ γδ T cells provides a sophisticated immunological mechanism regulating inflammation timing and resolution during skin repair.

PROS1 is a crucial gene in the macrophage efferocytosis of diabetic foot ulcers: a concerted analytical approach through the prisms of computer analysis

BACKGROUND

Diabetic foot ulcers (DFUs) pose a serious long-term threat because of elevated mortality and disability risks. Research on its biomarkers is still, however, very limited. In this paper, we have effectively identified biomarkers linked with macrophage excretion in diabetic foot ulcers through the application of bioinformatics and machine learning methodologies. These findings were subsequently validated using external datasets and animal experiments. Such discoveries are anticipated to offer novel insights and approaches for the early diagnosis and treatment of DFU.

METHODS

In this work, we used the Gene Expression Omnibus (GEO) database's datasets GSE68183 and GSE80178 as the training dataset to build a gene model using machine learning methods. After that, we used the training and validation sets to validate the model (GSE134431). On the model genes, we performed enrichment analysis using both gene set variant analysis (GSVA) and gene set enrichment analysis (GSEA). Additionally, the model genes were subjected to immunological association and immune function analyses.

RESULTS

In this study, PROS1 was identified as a potential key target associated with macrophage efflux in DFU by machine learning and bioinformatics approaches. Subsequently, the key biomarker status of PROS1 in DFU was also confirmed by external datasets. In addition, PROS1 also plays a key role in macrophage exudation in DFU. This gene may be associated with macrophage M1, CD4 memory T cells, naïve B cells, and macrophage M2, and affects IL-17, Rap1, hedgehog, and JAK-STAT signaling pathways.

CONCLUSIONS

PROS1 was identified and validated as a biomarker for DFU. This finding has the potential to provide a target for macrophage clearance of DFU.

Bioengineered MSCCxcr2 transdifferentiated keratinocyte-like cell-derived organoid potentiates skin regeneration through ERK1/2 and STAT3 signaling in diabetic wound

Skin regeneration is severely compromised in diabetic foot ulcers. Allogeneic mesenchymal stem cell (MSC) transplantation is limited due to the poor engraftment, mitogenic, and differentiation potential in the harsh wound microenvironment. Thus, to improve the efficacy of cell therapy, the chemokine receptor Cxcr2 was overexpressed in MSCs (MSCCxcr2). CXCL2/CXCR2 axis induction led to the enhanced proliferation of MSCs through the activation of STAT3 and ERK1/2 signaling. Transcriptional upregulation of FGFR2IIIb (KGF Receptor) promoter by the activated STAT3 and ERK1/2 suggested trans-differentiation of MSCs into keratinocytes. These stable MSCCxcr2 in 2D and 3D (spheroid) cell cultures efficiently transdifferentiated into keratinocyte-like cells (KLCs). An in vivo therapeutic potential of MSCCxcr2 transplantation and its keratinocyte-specific cell fate was observed by accelerated skin tissue regeneration in an excisional splinting wound healing murine model of streptozotocin-induced type 1 diabetes. Finally, 3D skin organoids generated using MSCCxcr2-derived KLCs upon grafting in a relatively avascular and non-healing wounds of type 2 diabetic db/db transgenic old mice resulted in a significant enhancement in the rate of wound closure by increased epithelialization (epidermal layer) and endothelialization (dermal layer). Our findings emphasize the therapeutic role of the CXCL2/CXCR2 axis in inducing trans-differentiation of the MSCs toward KLCs through the activation of ERK1/2 and STAT3 signaling and enhanced skin regeneration potential of 3D organoids grafting in chronic diabetic wounds.

Gelatin Microspheres Based on H8-Loaded Macrophage Membrane Vesicles to Promote Wound Healing in Diabetic Mice

Diabetic wound healing remains a worldwide challenge for both clinicians and researchers. The high expression of matrix metalloproteinase 9 (MMP9) and a high inflammatory response are indicative of poor diabetic wound healing. H8, a curcumin analogue, is able to treat diabetes and is anti-inflammatory, and our pretest showed that it has the potential to treat diabetic wound healing. However, H8 is highly expressed in organs such as the liver and kidney, resulting in its unfocused use in diabetic wound targeting. (These data were not published, see Table S1 in the Supporting Information.) Accordingly, it is important to pursue effective carrier vehicles to facilitate the therapeutic uses of H8. The use of H8 delivered by macrophage membrane-derived nanovesicles provides a potential strategy for repairing diabetic wounds with improved drug efficacy and fast healing. In this study, we fabricated an injectable gelatin microsphere (GM) with sustained MMP9-responsive H8 macrophage membrane-derived nanovesicles (H8NVs) with a targeted release to promote angiogenesis that also reduces oxidative stress damage and inflammation, promoting diabetic wound healing. Gelatin microspheres loaded with H8NV (GMH8NV) stimulated by MMP9 can significantly facilitate the migration of NIH-3T3 cells and facilitate the development of tubular structures by HUVEC in vitro. In addition, our results demonstrated that GMH8NV stimulated by MMP9 protected cells from oxidative damage and polarized macrophages to the M2 phenotype, leading to an inflammation inhibition. By stimulating angiogenesis and collagen deposition, inhibiting inflammation, and reducing MMP9 expression, GMH8NV accelerated wound healing. This study showed that GMH8NVs were targeted to release H8NV after MMP9 stimulation, suggesting promising potential in achieving satisfactory healing in diabetic treatment.

Role of the Skin Immune System in Wound Healing

Wound healing is a dynamic and complex process, characterized by the coordinated activities of multiple cell types, each with distinct roles in the stages of hemostasis, inflammation, proliferation, and remodeling. The cells of the immune system not only act as sentinels to monitor the skin and promote homeostasis, but they also play an important role in the process of skin wound repair. Skin-resident and recruited immune cells release cytokines and growth factors that promote the amplification of the inflammatory process. They also work with non-immune cells to remove invading pathogens and debris, as well as guide the regeneration of damaged host tissues. Dysregulation of the immune system at any stage of the process may lead to a prolongation of the inflammatory phase and the development of a pathological condition, such as a chronic wound. The present review aims to summarize the roles of different immune cells, with special emphasis on the different stages of the wound healing process.

Correlation between inflammatory factors, autophagy protein levels, and infection in granulation tissue of diabetic foot ulcer

OBJECTIVE

To observe the expression of inflammatory factors and autophagy-related proteins in granulation tissue of diabetic foot ulcer (DFU) patients and analyze their relationship with infection.

METHODS

This is a retrospective cohort study. One hundred and fifty-two patients with DFU in our hospital from July 2020 to March 2022 were selected as the DFU group, including 98 cases in infection stage group and 54 cases in infection control group. The patients were further graded as the mild (51 cases), the moderate (65 cases), and the severe infection group (36 cases) according to the Wagner grading criteria. Sixty-seven patients with foot burns during the same period were selected as the control group. The distribution of pathogenic bacteria on the ulcer surface was examined using fully automated bacterial analyzer. The expression of inflammatory factors (procalcitonin [PCT], tumor necrosis factor-α [TNF-α], and interleukin-6 [IL-6]) was valued by real-time fluorescence quantitative PCR (qRT-PCR). Protein expression was measured by immunohistochemistry (IHC). The correlation was analyzed by Pearson.

RESULTS

The surface infection of DFU patients was mostly induced by gram-negative and gram-positive bacteria, with Pseudomonas aeruginosa predominating among the Gram-negative bacteria and Staphylococcus aureus among the gram-positive bacteria. The infection stage group had higher content of PCT, TNF-α, and IL-6 and lower content of Beclin-1 and LC3 than the infection control group (p < .001). The levels of PCT, TNF-α, and IL-6 in the DFU patients with cardiovascular events were higher than those in the nonoccurrence group (p < .001). Glycated hemoglobin in patients with DFU was positively correlated with PCT, TNF-α, and IL-6 levels (p < .05), and negatively correlated with Beclin-1 and LC3 levels (p < .001).

CONCLUSION

P. aeruginosa and S. aureus were predominant bacterial in DFU infections. Inflammatory factor and autophagy protein expression were closely correlated with the degree of infection.

Acellular embryoid body and hydroxybutyl chitosan composite hydrogels promote M2 macrophage polarization and accelerate diabetic cutaneous wound healing

Diabetic wound healing is delayed due to persistent inflammation, and macrophage-immunomodulating biomaterials can control the inflammatory phase and shorten the healing time. In this study, acellular embryoid bodies (aEBs) were prepared and mixed with thermosensitive hydroxybutyl chitosan (HBC) hydrogels to produce aEB/HBC composite hydrogels. The aEB/HBC composite hydrogels exhibited reversible temperature-sensitive phase transition behavior and a hybrid porous network. In vitro analysis showed that the aEB/HBC composite hydrogels exhibited better antimicrobial activity than the PBS control, aEBs or HBC hydrogels and promoted M0 to M2 polarization but not M1 to M2 macrophage repolarization in culture. The in vivo results showed that the aEB/HBC composite hydrogels accelerated cutaneous wound closure, re-epithelialization, ingrowth of new blood vessels, and collagen deposition and reduced the scar width during wound healing in diabetic mice over time. Macrophage phenotype analysis showed that the aEB/HBC composite hydrogels induce M2 macrophage reactions continually, upregulate M2-related mRNA and protein expression and downregulate M1-related mRNA and protein expression. Therefore, the aEB/HBC composite hydrogels have excellent antimicrobial activity, promote M2 macrophage polarization and accelerate the functional and structural healing of diabetic cutaneous wounds.

Advancements in Regenerative Hydrogels in Skin Wound Treatment: A Comprehensive Review

This state-of-the-art review explores the emerging field of regenerative hydrogels and their profound impact on the treatment of skin wounds. Regenerative hydrogels, composed mainly of water-absorbing polymers, have garnered attention in wound healing, particularly for skin wounds. Their unique properties make them well suited for tissue regeneration. Notable benefits include excellent water retention, creating a crucially moist wound environment for optimal healing, and facilitating cell migration, and proliferation. Biocompatibility is a key feature, minimizing adverse reactions and promoting the natural healing process. Acting as a supportive scaffold for cell growth, hydrogels mimic the extracellular matrix, aiding the attachment and proliferation of cells like fibroblasts and keratinocytes. Engineered for controlled drug release, hydrogels enhance wound healing by promoting angiogenesis, reducing inflammation, and preventing infection. The demonstrated acceleration of the wound healing process, particularly beneficial for chronic or impaired healing wounds, adds to their appeal. Easy application and conformity to various wound shapes make hydrogels practical, including in irregular or challenging areas. Scar minimization through tissue regeneration is crucial, especially in cosmetic and functional regions. Hydrogels contribute to pain management by creating a protective barrier, reducing friction, and fostering a soothing environment. Some hydrogels, with inherent antimicrobial properties, aid in infection prevention, which is a crucial aspect of successful wound healing. Their flexibility and ability to conform to wound contours ensure optimal tissue contact, enhancing overall treatment effectiveness. In summary, regenerative hydrogels present a promising approach for improving skin wound healing outcomes across diverse clinical scenarios. This review provides a comprehensive analysis of the benefits, mechanisms, and challenges associated with the use of regenerative hydrogels in the treatment of skin wounds. In this review, the authors likely delve into the application of rational design principles to enhance the efficacy and performance of hydrogels in promoting wound healing. Through an exploration of various methodologies and approaches, this paper is poised to highlight how these principles have been instrumental in refining the design of hydrogels, potentially revolutionizing their therapeutic potential in addressing skin wounds. By synthesizing current knowledge and highlighting potential avenues for future research, this review aims to contribute to the advancement of regenerative medicine and ultimately improve clinical outcomes for patients with skin wounds.