High glucose environment induces M1 macrophage polarization that impairs keratinocyte migration via TNF-α: An important mechanism to delay the diabetic wound healing

Dried tangerine peel polysaccharide accelerates wound healing by recruiting anti-inflammatory macrophages

Macrophage polarization is a key process involved in wound healing. The continuous release of proinflammatory cytokines by macrophages inhibits the healing process of chronic wounds, such as diabetic wounds. To promote wound healing, it is important to change the phenotype of resident macrophages to prevent inflammation. We previously reported that dried tangerine peel polysaccharide (DTPP) binds to and inhibits the TLR4/MD-2 complex, which is crucial for the inflammatory activation of macrophages, suggesting the potential of DTPP in wound healing applications. Both zebrafish and mouse models were used to evaluate the therapeutic efficacy of DTPP. Moreover, we found that DTPP recruited macrophages to the wound area and promoted their M2 repolarization. Using hyperglycaemic zebrafish and db/db mouse models, we discovered that DTPP accelerated wound healing in vivo in metabolic disorders. Our results suggest that DTPP promotes the recruitment of macrophages, shifts macrophages towards the anti-inflammatory M2 phenotype, and ultimately accelerates the wound healing process.

High-glucose impact on UVB responses in human epidermal keratinocytes: Insights on diabetic skin's resistance to photocarcinogenesis

Ultraviolet (UV) B-induced damage in human epidermal keratinocytes (HEKs) initiates photocarcinogenesis. However, how diabetes influences photocarcinogenesis is not well understood. To investigate the impact of high-glucose environments on responses to UVB, we cultured HEKs in normal-glucose (NG) or high-glucose (HG) conditions (G6 and G26), followed by UVB irradiation at 25 mJ/cm2 (G6UVB and G26UVB). We performed next-generation sequencing and analyzed HEKs' expression profiles bioinformatically to identify candidate genes and cellular responses involved. We found UVB induced consistent responses in both NG- and HG-cultivated HEKs, but it also triggered certain distinct processes and pathways specifically in the HG groups. The 459 differentially expressed (DE) genes in the HG groups revealed their roles in chromatin remodeling, nucleosome assembly, and interferon signaling activation. Moreover, the 29 DE genes identified in G26UVB/G6UVB comparison, including the potent tumor suppressor gene TFPI2, were considered key genes contributing to HEKs' altered response to UVB in HG environments. UVB irradiation induced significantly higher TFPI2 expression in HG-cultivated HEKs than their NG-cultivated counterpart. Finally, HG-cultivation significantly increased oxidative stress, cyclobutane pyrimidine dimer formation, and apoptosis, while reducing HEKs' viability after UVB irradiation. These changes under HG conditions probably mediate cell fate toward death and tumor regression. Overall, our findings provide evidence and associated molecular basis on how HG conditions reduce keratinocytes' photocarcinogenic potential following UVB exposure.

Intrinsically bioactive multifunctional Poly(citrate-curcumin) for rapid lung injury and MRSA infection therapy

Dysregulated inflammation after trauma or infection could result in the further disease and delayed tissue reconstruction. The conventional anti-inflammatory drug treatment suffers to the poor bioavailability and side effects. Herein, we developed an amphiphilic multifunctional poly (citrate-polyglycol-curcumin) (PCGC) nano oligomer with the robust anti-inflammatory activity for treating acute lung injury (ALI) and Methicillin-resistant staphylococcus aureus (MRSA) infected wound. PCGC demonstrated the sustained curcumin release, inherent photoluminescence, good cellular compatibility, hemocompatibility, robust antioxidant activity and enhanced cellular uptake. PCGC could efficiently scavenge nitrogen-based free radicals, oxygen-based free radicals, and intracellular oxygen species, enhance the endothelial cell migration and reduce the expression of pro-inflammatory factors through the NF-κB signal pathway. Combined the anti-inflammation and antioxidant properties, PCGC can shortened the inflammatory process. In animal model of ALI, PCGC was able to reduce the pulmonary edema, bronchial cell infiltration, and lung inflammation, while exhibiting rapid metabolic behavior in vivo. The MRSA-infection wound model showed that PCGC significantly reduced the expression of pro-inflammatory factors, promoted the angiogenesis and accelerated the wound healing. The transcriptome sequencing and molecular mechanism studies further demonstrated that PCGC could inhibit multiple inflammatory related pathways including TNFAIP3, IL-15RA, NF-κB. This work demonstrates that PCGC is efficient in resolving inflammation and promotes the prospect of application in inflammatory diseases as the drug-loaded therapeutic system.

Mangiferin Represses Inflammation in Macrophages Under a Hyperglycemic Environment Through Nrf2 Signaling

Inflammation in macrophages is exacerbated under hyperglycemic conditions, contributing to chronic inflammation and impaired wound healing in diabetes. This study investigates the potential of mangiferin, a natural polyphenol, to alleviate this inflammatory response by targeting a redox-sensitive transcription factor, nuclear factor erythroid 2-related factor 2 (Nrf2). Mangiferin, a known Nrf2 activator, was evaluated for its ability to counteract the hyperglycemia-induced inhibition of Nrf2 and enhance antioxidant defenses. The protective effects of mangiferin on macrophages in a hyperglycemic environment were assessed by examining the expression of Nrf2, NF-κB, NLRP3, HO-1, CAT, COX-2, IL-6, and IL-10 through gene and protein expression analyses using qPCR and immunoblotting, respectively. The mangiferin-mediated nuclear translocation of Nrf2 was evidenced, leading to a robust antioxidant response in macrophages exposed to a hyperglycemic microenvironment. This activation suppressed NF-κB signaling, reducing the expression of pro-inflammatory mediators such as COX-2 and IL-6. Additionally, mangiferin decreased NLRP3 inflammasome activation and reactive oxygen species accumulation in hyperglycemia exposed macrophages. Our findings revealed that mangiferin alleviated hyperglycemia-induced reductions in AKT phosphorylation, highlighting its potential role in modulating key signaling pathways. Furthermore, mangiferin significantly enhanced the invasiveness and migration of macrophages in a hyperglycemic environment, indicating its potential to improve wound healing. In conclusion, this study suggests that mangiferin may offer a promising therapeutic approach for managing inflammation and promoting wound healing in diabetic patients by regulating Nrf2 activity in hyperglycemia-induced macrophages.

Zinc-based Polyoxometalate Nanozyme Functionalized Hydrogels for optimizing the Hyperglycemic-Immune Microenvironment to Promote Diabetic Wound Regeneration

BACKGROUND

In diabetic wounds, hyperglycemia-induced cytotoxicity and impaired immune microenvironment plasticity directly hinder the wound healing process. Regulation of the hyperglycemic microenvironment and remodeling of the immune microenvironment are crucial.

RESULTS

Here, we developed a nanozymatic functionalized regenerative microenvironmental regulator (AHAMA/CS-GOx@Zn-POM) for the effective repair of diabetic wounds. This novel construct integrated an aldehyde and methacrylic anhydride-modified hyaluronic acid hydrogel (AHAMA) and chitosan nanoparticles (CS NPs) encapsulating zinc-based polymetallic oxonate nanozyme (Zn-POM) and glucose oxidase (GOx), facilitating a sustained release of release of both enzymes. The GOx catalyzed glucose to gluconic acid and (H₂O₂), thereby alleviating the effects of the hyperglycemic microenvironment on wound healing. Zn-POM exhibited catalase and superoxide dismutase activities to scavenge reactive oxygen species and H₂O₂, a by-product of glucose degradation. Additionally, Zn-POM induced M1 macrophage reprogramming to the M2 phenotype by inhibiting the MAPK/IL-17 signaling diminishing pro-inflammatory cytokines, and upregulating the expression of anti-inflammatory mediators, thus remodeling the immune microenvironment and enhancing angiogenesis and collagen regeneration within wounds. In a rat diabetic wound model, the application of AHAMA/CS-GOx@Zn-POM enhanced neovascularization and collagen deposition, accelerating the wound healing process.

CONCLUSIONS

Therefore, the regenerative microenvironment regulator AHAMA/CS-GOx@Zn-POM can achieve the effective conversion of a pathological microenvironment to regenerative microenvironment through integrated control of the hyperglycemic-immune microenvironment, offering a novel strategy for the treatment of diabetic wounds.

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.

Impact of hyperglycemia on immune cell function: a comprehensive review

Hyperglycemia, a hallmark of diabetes and various metabolic disorders, has profound implications for immune cell function. The relationship between elevated blood glucose levels and immune cell function is a topic of significant medical interest. In this review, we aim to comprehensively review effects of hyperglycemia on various immune cell types and its clinical implications, particularly T cells, macrophages, natural killer cells, and neutrophils. It aims to consolidate current knowledge on the subject, with a focus on both type 1 and type 2 diabetes, as well as other pathological states where hyperglycemia is a concern. A comprehensive examination of recent studies and clinical data was conducted to assess effects of hyperglycemia on immune cell function. Evidence indicates that hyperglycemia can significantly alter immune cell function, with different diabetic conditions showing varied responses. Roles of key metabolic hormones in regulating T cell function highlight potential therapeutic targets for restoring immune balance. In addition, reprogramming of innate immune cells such as macrophages and natural killer cells under hyperglycemic conditions suggests a complex metabolic-immunological interface. This review will contribute to a better understanding of the link between diabetes, other metabolic disorders, and immune function. By examining recent research and clinical findings, this review will enhance our comprehension of the mechanisms at play and guide future medical strategies for managing and treating conditions associated with hyperglycemia.

Advancements in diabetic foot ulcer research: Focus on mesenchymal stem cells and their exosomes

Diabetes represents a widely acknowledged global public health concern. Diabetic foot ulcer (DFU) stands as one of the most severe complications of diabetes, its occurrence imposing a substantial economic burden on patients, profoundly impacting their quality of life. Despite the deepening comprehension regarding the pathophysiology and cellular as well as molecular responses of DFU, the current therapeutic arsenal falls short of efficacy, failing to offer a comprehensive remedy for deep-seated chronic wounds and microvascular occlusions. Conventional treatments merely afford symptomatic alleviation or retard the disease's advancement, devoid of the capacity to effectuate further restitution of compromised vasculature and nerves. An escalating body of research underscores the prominence of mesenchymal stem cells (MSCs) owing to their paracrine attributes and anti-inflammatory prowess, rendering them a focal point in the realm of chronic wound healing. Presently, MSCs have been validated as a highly promising cellular therapeutic approach for DFU, capable of effectuating cellular repair, epithelialization, granulation tissue formation, and neovascularization by means of targeted differentiation, angiogenesis promotion, immunomodulation, and paracrine activities, thereby fostering wound healing. The secretome of MSCs comprises cytokines, growth factors, chemokines, alongside exosomes harboring mRNA, proteins, and microRNAs, possessing immunomodulatory and regenerative properties. The present study provides a systematic exposition on the etiology of DFU and elucidates the intricate molecular mechanisms and diverse functionalities of MSCs in the context of DFU treatment, thereby furnishing pioneering perspectives aimed at harnessing the therapeutic potential of MSCs for DFU management and advancing wound healing processes.

Shaping the immune landscape: Multidimensional environmental stimuli refine macrophage polarization and foster revolutionary approaches in tissue regeneration

In immunology, the role of macrophages extends far beyond their traditional classification as mere phagocytes; they emerge as pivotal architects of the immune response, with their function being significantly influenced by multidimensional environmental stimuli. This review investigates the nuanced mechanisms by which diverse external signals ranging from chemical cues to physical stress orchestrate macrophage polarization, a process that is crucial for the modulation of immune responses. By transitioning between pro-inflammatory (M1) and anti-inflammatory (M2) states, macrophages exhibit remarkable plasticity, enabling them to adapt to and influence their surroundings effectively. The exploration of macrophage polarization provides a compelling narrative on how these cells can be manipulated to foster an immune environment conducive to tissue repair and regeneration. Highlighting cutting-edge research, this review presents innovative strategies that leverage the dynamic interplay between macrophages and their environment, proposing novel therapeutic avenues that harness the potential of macrophages in regenerative medicine. Moreover, this review critically evaluates the current challenges and future prospects of translating macrophage-centered strategies from the laboratory to clinical applications.

Phytoconstituents as modulators of NF-κB signalling: Investigating therapeutic potential for diabetic wound healing

The NF-κB pathway plays a pivotal role in impeding the diabetic wound healing process, contributing to prolonged inflammation, diminished angiogenesis, and reduced proliferation. In contrast to modern synthetic therapies, naturally occurring phytoconstituents are well-studied inhibitors of the NF-κB pathway that are now attracting increased attention in the context of diabetic wound healing because of lower toxicity, better safety and efficacy, and cost-effectiveness. This study explores recent research on phytoconstituent-based therapies and delve into their action mechanisms targeting the NF-κB pathway and potential for assisting effective healing of diabetic wounds. For this purpose, we have carried out surveys of recent literature and analyzed studies from prominent databases such as Science Direct, Scopus, PubMed, Google Scholar, EMBASE, and Web of Science. The classification of phytoconstituents into various categorie such as: alkaloids, triterpenoids, phenolics, polyphenols, flavonoids, monoterpene glycosides, naphthoquinones and tocopherols. Noteworthy phytoconstituents, including Neferine, Plumbagin, Boswellic acid, Genistein, Luteolin, Kirenol, Rutin, Vicenin-2, Gamma-tocopherol, Icariin, Resveratrol, Mangiferin, Betulinic acid, Berberine, Syringic acid, Gallocatechin, Curcumin, Loureirin-A, Loureirin-B, Lupeol, Paeoniflorin, and Puerarin emerge from these studies as promising agents for diabetic wound healing through the inhibition of the NF-κB pathway. Extensive research on various phytoconstituents has revealed how they modulate signalling pathways, including NF-κB, studies that demonstrate the potential for development of therapeutic phytoconstituents to assist healing of chronic diabetic wounds.

A poly (lactic-co-glycolic acid) self-pumping Janus dressing with bidirectional biofluid transport for diabetic wound healing via anti-bacteria and pro-angiogenesis

Diabetic wound healing poses a substantial challenge owing to bacterial infections, insufficient angiogenesis, and excessive exudates. Currently, most of the clinical dressings used for diabetic wounds are still conventional dressings such as gauze. In this study, a three-layer Janus dressing was developed via continuous electrostatic spinning. The top-layer was composed of polylactic acid-glycolic acid and hydroxyapatite doped with silver ions and silicate. The hydrophobic top-layer prevented the adhesion of foreign bacteria. The mid-layer was composed of polyethylene glycol, polylactic acid-glycolic acid and hydroxyapatite doped with silver ions and silicate facilitated exudate absorption and bioactive ion release. The modified sub-layer containing polylactic acid-glycolic acid, hydroxyapatite doped with silver ions and silicate and sodium alginate microspheres enabled both the transport of wound exudate from the wound bed to dressing and the backflow of bioactive silver ions and silicate to the wound bed, thereby reducing infection and stimulating angiogenesis. Through in vivo and in vivo experiments, the Janus dressing showed to have antimicrobial, angiogenic, and exudate-control properties that accelerate healing in diabetic wounds. As a novel dressing, the multifunctional, self-pumping Janus wound dressing with bi-directional biofluidic transport offers a new approach to diabetic wound healing.

Metabolomic analysis reveals macrophage metabolic reprogramming and polarization under different nutritional cues

BACKGROUND AND AIMS

Obesity-induced chronic inflammation and metabolic abnormalities are highly relevant to the functional dysregulation of macrophages, especially under obese conditions. Hyperglycemia and hyperlipidemia, central to obesity, directly alter macrophage activity. However, the impacts of different nutritional cues on the intricate metabolic networks in macrophages remain unclear.

MATERIALS AND METHODS

In this study, we employed metabolomic approaches to examine the metabolic responses of macrophages to high glucose, high fat and their coexistence, aiming to delineate the molecular mechanisms of nutritional factors on macrophage activation and obesity-related diseases from a metabolic perspective.

RESULTS

Our findings revealed that different nutritional conditions could reprogram key metabolism in macrophages. Additionally, we identified a metabolite derived from macrophages, Long-Chain Phosphatidylcholine (LPC), which exerts beneficial effects on obese mice. It ameliorates the obesity phenotype and improves glucose metabolism profiles. This discovery suggests that LPC has a significant therapeutic potential in the context of obesity-induced metabolic dysfunctions. Our study unveils the metabolic phenotype of macrophages in high-fat and high-sugar environments and uncovers a macrophage-derived metabolite that significantly ameliorates the obesity phenotype.

CONCLUSION

This finding reveals a potential dialogue mechanism between macrophages and adipocytes, shedding light on the complex interplay of immune and metabolic systems in obesity. This discovery not only enhances our understanding of obesity's underlying mechanisms but also opens up new avenues for therapeutic interventions targeting macrophage-adipocyte interactions.

Mesoporous MOFs with ROS scavenging capacity for the alleviation of inflammation through inhibiting stimulator of interferon genes to promote diabetic wound healing

Excessive production of reactive oxygen species (ROS) and inflammation are the key problems that impede diabetic wound healing. In particular, dressings with ROS scavenging capacity play a crucial role in the process of chronic wound healing. Herein, Zr-based large-pore mesoporous metal-organic frameworks (mesoMOFs) were successfully developed for the construction of spatially organized cascade bioreactors. Natural superoxide dismutase (SOD) and an artificial enzyme were spatially organized in these hierarchical mesoMOFs, forming a cascade antioxidant defense system, and presenting efficient intracellular and extracellular ROS scavenging performance. In vivo experiments demonstrated that the SOD@HMUiO-MnTCPP nanoparticles (S@M@H NPs) significantly accelerated diabetic wound healing. Transcriptomic and western blot results further indicated that the nanocomposite could inhibit fibroblast senescence and ferroptosis as well as the stimulator of interferon genes (STING) signaling pathway activation in macrophages mediated by mitochondrial oxidative stress through ROS elimination. Thus, the biomimetic multi-enzyme cascade catalytic system with spatial ordering demonstrated a high potential for diabetic wound healing, where senescence, ferroptosis, and STING signaling pathways may be potential targets.

New approaches to second-degree burn healing: Polyvinyl alcohol membrane loaded to arnica combined to laser therapy

Second-degree burns require greater care, as the damage is more extensive and worrisome and the use of a biomaterial can help in the cell repair process, with better planning, low cost, and better accessibility. Arnica has anti-inflammatory and analgesic properties in skin lesions treatments and laser therapy is another therapeutic alternative for burns. Evaluate the effects of arnica incorporated into PVA associated or not with low intensity laser on burns in rats. PVA and PVA with arnica (PVA+A) were obtained and characterized physicochemically. Through in vivo studies, the effects of PVA and PVA+A with or without the application of laser on the lesions allowed histological and immunohistochemical analyzes. PVA+A was biocompatible and with sustained release of the active, being a promising pharmacological tool and confirmed that laser therapy was effective in accelerating the healing process, due to its potential biomodulator, improving inflammatory aspects, promoting rapid healing in skin lesions.

A Multifunctional Nanozyme Integrating Antioxidant, Antimicrobial and Pro-Vascularity for Skin Wound Management

Background

Skin wounds are a prevalent issue that can have severe health consequences if not treated correctly. Nanozymes offer a promising therapeutic approach for the treatment of skin wounds, owing to their advantages in regulating redox homeostasis to reduce oxidative damage and kill bacteria. These properties make them an effective treatment option for skin wounds. However, most of current nanozymes lack the capability to simultaneously address inflammation, oxidative stress, and bacterial infection during the wound healing process. There is still great potential for nanozymes to increase their therapeutic functional diversity and efficacy.

Methods

Herein, copper-doped hollow mesopores cerium oxide (Cu-HMCe) nanozymes with multifunctional of antioxidant, antimicrobial and pro-vascularity is successfully prepared. Cu-HMCe can be efficiently prepared through a simple and rapid solution method and displays sound physiological stability. The biocompatibility, pro-angiogenic, antimicrobial, and antioxidant properties of Cu-HMCe were assessed. Moreover, a full-thickness skin defect infection model was utilized to investigate the wound healing capacity, as well as anti-inflammatory and pro-angiogenic properties of nanozymes in vivo.

Results

Both in vitro and in vivo experiments have substantiated Cu-HMCe's remarkable biocompatibility. Moreover, Cu-HMCe possesses potent antioxidant enzyme-like catalytic activity, effectively clearing DPPH radicals (with a scavenging rate of 80%), hydroxyl radicals, and reactive oxygen species. Additionally, Cu-HMCe exhibits excellent antimicrobial and pro-angiogenic properties, with over 70% inhibition of both E. coli and S. aureus. These properties collectively promote wound healing, and the wound treated with Cu-HMCe achieved a closure rate of over 90% on the 14th day.

Conclusion

The results indicate that multifunctional Cu-HMCe with antioxidant, antimicrobial, and pro-angiogenic properties was successfully prepared and exhibited remarkable efficacy in promoting wound healing. This nanozymes providing a promising strategy for skin repair.

Unraveling the complex roles of macrophages in obese adipose tissue: an overview

Macrophages, a heterogeneous population of innate immune cells, exhibit remarkable plasticity and play pivotal roles in coordinating immune responses and maintaining tissue homeostasis within the context of metabolic diseases. The activation of inflammatory macrophages in obese adipose tissue leads to detrimental effects, inducing insulin resistance through increased inflammation, impaired thermogenesis, and adipose tissue fibrosis. Meanwhile, adipose tissue macrophages also play a beneficial role in maintaining adipose tissue homeostasis by regulating angiogenesis, facilitating the clearance of dead adipocytes, and promoting mitochondrial transfer. Exploring the heterogeneity of macrophages in obese adipose tissue is crucial for unraveling the pathogenesis of obesity and holds significant potential for targeted therapeutic interventions. Recently, the dual effects and some potential regulatory mechanisms of macrophages in adipose tissue have been elucidated using single-cell technology. In this review, we present a comprehensive overview of the intricate activation mechanisms and diverse functions of macrophages in adipose tissue during obesity, as well as explore the potential of drug delivery systems targeting macrophages, aiming to enhance the understanding of current regulatory mechanisms that may be potentially targeted for treating obesity or metabolic diseases.

Mesenchymal stem cell therapy in diabetic foot ulcer: An updated comprehensive review

Background

Diabetes has evolved into a worldwide public health issue. One of the most serious complications of diabetes is diabetic foot ulcer (DFU), which frequently creates a significant financial strain on patients and lowers their quality of life. Up until now, there has been no curative therapy for DFU, only symptomatic relief or an interruption in the disease's progression. Recent studies have focused attention on mesenchymal stem cells (MSCs), which provide innovative and potential treatment candidates for several illnesses as they can differentiate into various cell types. They are mostly extracted from the placenta, adipose tissue, umbilical cord (UC), and bone marrow (BM). Regardless of their origin, they show comparable features and small deviations. Our goal is to investigate MSCs' therapeutic effects, application obstacles, and patient benefit strategies for DFU therapy.

Methodology

A comprehensive search was conducted using specific keywords relating to DFU, MSCs, and connected topics in the databases of Medline, Scopus, Web of Science, and PubMed. The main focus of the selection criteria was on English-language literature that explored the relationship between DFU, MSCs, and related factors.

Results and Discussion

Numerous studies are being conducted and have demonstrated that MSCs can induce re-epithelialization and angiogenesis, decrease inflammation, contribute to immunological modulation, and subsequently promote DFU healing, making them a promising approach to treating DFU. This review article provides a general snapshot of DFU (including clinical presentation, risk factors and etiopathogenesis, and conventional treatment) and discusses the clinical progress of MSCs in the management of DFU, taking into consideration the side effects and challenges during the application of MSCs and how to overcome these challenges to achieve maximum benefits.

Conclusion

The incorporation of MSCs in the management of DFU highlights their potential as a feasible therapeutic strategy. Establishing a comprehensive understanding of the complex relationship between DFU pathophysiology, MSC therapies, and related obstacles is essential for optimizing therapy outcomes and maximizing patient benefits.

CD64 plays a key role in diabetic wound healing

Introduction

Wound healing poses a clinical challenge in diabetes mellitus (DM) due to compromised host immunity. CD64, an IgG-binding Fcgr1 receptor, acts as a pro-inflammatory mediator. While its presence has been identified in various inflammatory diseases, its specific role in wound healing, especially in DM, remains unclear.

Objectives

We aimed to investigate the involvement of CD64 in diabetic wound healing using a DM animal model with CD64 KO mice.

Methods

First, we compared CD64 expression in chronic skin ulcers from human DM and non-DM skin. Then, we monitored wound healing in a DM mouse model over 10 days, with or without CD64 KO, using macroscopic and microscopic observations, as well as immunohistochemistry.

Results

CD64 expression was significantly upregulated (1.25-fold) in chronic ulcerative skin from DM patients compared to non-DM individuals. Clinical observations were consistent with animal model findings, showing a significant delay in wound healing, particularly by day 7, in CD64 KO mice compared to WT mice. Additionally, infiltrating CD163+ M2 macrophages in the wounds of DM mice decreased significantly compared to non-DM mice over time. Delayed wound healing in DM CD64 KO mice correlated with the presence of inflammatory mediators.

Conclusion

CD64 seems to play a crucial role in wound healing, especially in DM conditions, where it is associated with CD163+ M2 macrophage infiltration. These data suggest that CD64 relies on host immunity during the wound healing process. Such data may provide useful information for both basic scientists and clinicians to deal with diabetic chronic wound healing.

Highly Bioactive MXene-M2-Exosome Nanocomposites Promote Angiogenic Diabetic Wound Repair through Reconstructing High Glucose-Derived Immune Inhibition

The repair of diabetic wounds remains challenging, primarily due to the high-glucose-derived immune inhibition which often leads to the excessive inflammatory response, impaired angiogenesis, and heightened susceptibility to infection. However, the means to reduce the immunosuppression and regulate the conversion of M2 phenotype macrophages under a high-glucose microenvironment using advanced biomaterials for diabetic wounds are not yet fully understood. Herein, we report two-dimensional carbide (MXene)-M2 macrophage exosome (Exo) nanohybrids (FM-Exo) for promoting diabetic wound repair by overcoming the high-glucose-derived immune inhibition. FM-Exo showed the sustained release of M2 macrophage-derived exosomes (M2-Exo) up to 7 days and exhibited broad-spectrum antibacterial activity. In the high-glucose microenvironment, relative to the single Exo, FM-Exo could significantly induce the optimized M2a/M2c polarization ratio of macrophages by activating the PI3K/Akt signaling pathway, promoting the proliferation, migration of fibroblasts, and angiogenic ability of endothelial cells. In the diabetic full-thickness wound model, FM-Exo effectively regulated the polarization status of macrophages and promoted their transition to the M2 phenotype, thereby inhibiting inflammation, promoting angiogenesis through VEGF secretion, and improving proper collagen deposition. As a result, the healing process was accelerated, leading to a better healing outcome with reduced scarring. Therefore, this study introduced a promising approach to address diabetic wounds by developing bioactive nanomaterials to regulate immune inhibition in a high-glucose environment.

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

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

Photothermal-enhanced in situ supramolecular hydrogel promotes bacteria-infected wound healing in diabetes

Bacterial infection can impede the healing of chronic wounds, particularly diabetic wounds. The high-sugar environment of diabetic wounds creates a favorable condition for bacterial growth, posing a challenge to wound healing. In clinical treatment, the irregular shape of the wound and the poor mechanical properties of traditional gel adjuvants make them susceptible to mechanical shear and compression, leading to morphological changes and fractures, and difficult to adapt to irregular wounds. Traditional gel adjuvants are prepared in advance, while in situ gel is formed at the site of administration after drug delivery in a liquid state, which can better fit the shape of the wound. Therefore, this study developed an in situ HA/GCA/Fe2+-GOx gel using a photothermal-enhanced Fenton reaction to promote the generation of hydroxyl radicals (·OH). The generation of ·OH has an antibacterial effect while promoting the formation of the gel, achieving a dual effect. The addition of double-bonded adamantane (Ada) interacts with the host-guest effect of graphene oxide and the double-bond polymerization of HAMA gel, making the entire gel system more complete. At the same time, the storage modulus (G') of the gel increased from 130 to 330 Pa, enhancing the mechanical properties of the gel. This enables the gel to have better injectability and self-healing effects. The addition of GOx can consume glucose at the wound site, providing a good microenvironment for the repair of diabetic wounds. The gel has good biocompatibility and in a diabetic rat wound model infected with S. aureus, it can effectively kill bacteria at the wound site and promote wound repair. Meanwhile, the inflammation of wounds treated with HA/GCA/Fe2+-GOx + NIR was lighter compared to untreated wounds. Therefore, this study provides a promising strategy for treating bacterial-infected diabetic wounds.

Recent advances of hydrogels as smart dressings for diabetic wounds

Chronic diabetic wounds have been an urgent clinical problem, and wound dressings play an important role in their management. Due to the design of traditional dressings, it is difficult to achieve adaptive adhesion and on-demand removal of complex diabetic wounds, real-time monitoring of wound status, and dynamic adjustment of drug release behavior according to the wound microenvironment. Smart hydrogels, as smart dressings, can respond to environmental stimuli and achieve more precise local treatment. Here, we review the latest progress of smart hydrogels in wound bandaging, dynamic monitoring, and drug delivery for treatment of diabetic wounds. It is worth noting that we have summarized the most important properties of smart hydrogels for diabetic wound healing. In addition, we discuss the unresolved challenges and future prospects in this field. We hope that this review will contribute to furthering progress on smart hydrogels as improved dressing for diabetic wound healing and practical clinical application.

Immunomodulation in diabetic wounds healing: The intersection of macrophage reprogramming and immunotherapeutic hydrogels

Diabetic wound healing presents a significant clinical challenge due to the interplay of systemic metabolic disturbances and local inflammation, which hinder the healing process. Macrophages undergo a phenotypic shift from M1 to M2 during wound healing, a transition pivotal for effective tissue repair. However, in diabetic wounds, the microenvironment disrupts this phenotypic polarization, perpetuating inflammation, and impeding healing. Reprograming macrophages to restore their M2 phenotype offers a potential avenue for modulating the wound immune microenvironment and promoting healing. This review elucidates the mechanisms underlying impaired macrophage polarization toward the M2 phenotype in diabetic wounds and discusses novel strategies, including epigenetic and metabolic interventions, to promote macrophage conversion to M2. Hydrogels, with their hydrated 3D cross-linked structure, closely resemble the physiological extracellular matrix and offer advantageous properties such as biocompatibility, tunability, and versatility. These characteristics make hydrogels promising candidates for developing immunomodulatory materials aimed at addressing diabetic wounds. Understanding the role of hydrogels in immunotherapy, particularly in the context of macrophage reprograming, is essential for the development of advanced wound care solutions. This review also highlights recent advancements in immunotherapeutic hydrogels as a step toward precise and effective treatments for diabetic wounds.

High glucose environment induces NEDD4 deficiency that impairs angiogenesis and diabetic wound healing

BACKGROUND

Healing of diabetic wounds, characterized by impaired angiogenesis, remains a clinical challenge. E3 ligase have been identified as potential therapeutic targets of wound healing.

OBJECTIVE

We assessed the role of E3 ligase NEDD4 in the context of angiogenesis and diabetic wound healing.

METHODS

The mRNA expression levels of NEDD4, TSP1 and VEGF were determined by real-time PCR. Western blotting was used to evaluate the protein expression of NEDD4, TSP1 and VEGF. The ubiquitination of TSP1 was evaluated by immunoprecipitation. MTT assay, wound healing assay and tube formation assay were performed to assess the proliferation, migration and angiogenic functions of endothelial cells. The epigenetic modification in the promoter of NEDD4 was confirmed using BSP assay and ChIP-qPCR assay. The role of NEDD4 in wound healing was further verified in diabetic mouse model.

RESULTS

NEDD4 promotes proliferation, migration and tube formation of endothelial cells. It binds to and ubiquitinates TSP1, which lead to TSP1 degradation and thus increased VEGF expression. The inhibitory effect of NEDD4 silencing on the angiogenesis ability of endothelial cells can be restored by TSP1 knockdown. NEDD4 is reduced in diabetic patients, which may due to hypermethylation of NEDD4 promoter mediated via DNMT1 under high glucose condition. Furthermore, inhibition of NEDD4 represses wound healing in diabetic mouse model.

CONCLUSION

NEDD4 might promote angiogenesis and wound healing by inhibiting TSP1 via ubiquitination in diabetic patients.

Repurposing alagebrium for diabetic foot ulcer healing: Impact on AGEs/NFκB/NOX1 signaling

BACKGROUND

Diabetic foot ulcer (DFU) is a common diabetic complication associated with disability and reduced quality of life. Available therapeutics are not sufficient to combat the spread of DFU. Here we aim to investigate the impact of alagebrium, an advanced glycation end product (AGE)-crosslink breaker, on the healing of DFU.

METHODS

Diabetes was induced in Wistar rats by STZ, and after four weeks, wound was induced on the foot. Alagebrium (10 mg/kg) was administered orally for 14 days, and wound size was measured every 3 days. Behavioral tests i.e., hot plate and footprint tests, were performed to assess sensory function and gait. Blood was collected to assess HbA1c, serum AGEs, MDA and NOX1. Tissue was collected to assess histological changes and expression of NF-κB, iNOS, TNF-α, VEGF and EGF. In a subsequent set of experiments with similar design, alagebrium was applied topically as a film-forming gel.

RESULTS

Systemic alagebrium treatment accelerated the healing of diabetic wound, improved sensory functions and gait, and ameliorated histological changes. It also reduced serum levels of AGEs, MDA and NOX1, and the tissue expression of NF-κB, iNOS, TNF-α, and increased VEGF and EGF in diabetic rats. Topical alagebrium led to similar beneficial effects i.e., accelerated diabetic wound healing, improved wound histological changes, reduced expression of NF-κB and iNOS and increased VEGF.

CONCLUSIONS

Our findings suggest repurposing of alagebrium for the management of DFU to accelerate the healing process and improve the clinical outcomes in diabetic patients.

Based on Clinical Research Matrix Metalloprotease (MMP) Inhibitors to Promote Diabetic Wound Healing

Chronic inflammation is a common factor in obesity, diabetes mellitus, and the complications of diabetes, including diabetic wounds. These ulcers are characterized by persistent lesions that are challenging to heal, significantly decreasing patients' quality of life and imposing a substantial financial burden on society. MMP are zinc endopeptidases that play a role in wound healing in response to various stimuli, including diabetes mellitus. MMP levels fluctuate throughout the wound healing process in diabetic patients' serum, skin tissues, and wound fluid, indicating their potential as biomarkers for diabetic foot ulcers. Targeting MMP has emerged as a promising strategy for treating diabetic wounds, as these enzymes are involved in critical biological processes related to wound healing, including extracellular matrix secretion, angiogenesis, granulation tissue formation, collagen growth, re-epithelization, inflammatory response, and oxidative stress.

Harnessing strategies for enhancing diabetic wound healing from the perspective of spatial inflammation patterns

Diabetic wound is a great threat to patient's health and lives. The refractory diabetic wound shows spatial inflammation patterns, in which the early-wound pattern depicts a deprived acute inflammatory response, and the long-term non-healing wound pattern delineates an excessive and persistent inflammation due to the delayed immune cell infiltration in a positive feedback loop. In this work, we give points to some strategies to normalize the dysregulated immune process based on the spatial inflammation pattern differences in diabetic wound healing. First of all, inhibiting inflammatory response to avoid subsequent persistent and excessive immune infiltration for the early diabetic wound is proposed. However, diabetic wounds are unperceptive trauma that makes patients miss the best treatment time. Therefore, we also introduce two strategies for the long-term non-healing diabetic wound. One strategy is about changing chronic wounds to acute ones, which aims to rejuvenate M1 macrophages in diabetic wounds and make spontaneous M2 polarization possible. To activate the controllable proinflammatory response, western medicine delivers proinflammatory molecules while traditional Chinese medicine develops "wound-pus promoting granulation tissue growth theory". Another strategy to solve long-term non-healing wounds is seeking switches that target M1/M2 transition directly. These investigations draw a map that delineates strategies for enhancing diabetic wound healing from the perspective of spatial inflammation patterns systematically.

Engineering homologous platelet-rich plasma, platelet-rich plasma-derived exosomes, and mesenchymal stem cell-derived exosomes-based dual-crosslinked hydrogels as bioactive diabetic wound dressings

The management of diabetic wounds remains a critical therapeutic challenge. Platelet-rich plasma (PRP) gel, PRP-derived exosomes (PRP-Exos), and mesenchymal stem cell-derived exosomes (MSC-Exos) have demonstrated therapeutic potential in wound treatment. Unfortunately, their poor mechanical properties, the short half-lives of growth factors (GFs), and the burst release of GFs and exosomes have limited their clinical applications. Furthermore, proteases in diabetic wounds degrade GFs, which hampers wound repair. Silk fibroin is an enzyme-immobilization biomaterial that could protect GFs from proteases. Herein, we developed novel dual-crosslinked hydrogels based on silk protein (SP) (sericin and fibroin), including SP@PRP, SP@MSC-Exos, and SP@PRP-Exos, to promote diabetic wound healing synergistically. SP@PRP was prepared from PRP and SP using calcium gluconate/thrombin as agonist, while SP@PRP-Exos and SP@MSC-Exos were derived from exosomes and SP with genipin as crosslinker. SP provided improved mechanical properties and enabled the sustained release of GFs and exosomes, thereby overcoming the limitations of PRP and exosomes in wound healing. The dual-crosslinked hydrogels displayed shear-induced thinning, self-healing, and eradication of microbial biofilms in a bone-mimicking environment. In vivo, the dual-crosslinked hydrogels contributed to faster diabetic wound healing than PRP and SP by upregulating GFs expression, down-regulating matrix metalloproteinase-9 expression, and by promoting an anti-NETotic effect, angiogenesis, and re-epithelialization. Hence, these dual-crosslinked hydrogels have the potential to be translated into a new generation of diabetic wound dressings.

Research hotspot and trend of chronic wounds: A bibliometric analysis from 2013 to 2022

Chronic wounds have been confirmed as a vital health problem facing people in the global population aging process. While significant progress has been achieved in the study of chronic wounds, the treatment effect should be further improved. The number of publications regarding chronic wounds has been rising rapidly. In this study, bibliometric analysis was conducted to explore the hotspots and trends in the research on chronic wounds. All relevant studies on chronic wounds between 2013 and 2022 were collected from the PubMed database of the Web of Science (WOS) and the National Center for Biotechnology Information (NCBI). The data were processed and visualised using a series of software. On that basis, more insights can be gained into hotspots and trends of this research field. Wound Repair and Regeneration has the highest academic achievement in the field of chronic wound research. The United States has been confirmed as the most productive country, and the University of California System ranks high among other institutions. Augustin, M. is the author of the most published study, and Frykberg, RG et al. published the most cited study. Furthermore, the hotspots of wound research over the last decade were identified (e.g., bandages, infection and biofilms, pathophysiology and therapy). This study will help researchers gain insights into chronic wound research's hotspots and trends accurately and quickly. Moreover, the exploration of bacterial biofilm and the pathophysiological mechanism of the chronic wound will lay a solid foundation and clear direction for treating chronic wounds.

Hyperglycemia-activated 11β-hydroxysteroid dehydrogenase type 1 increases endoplasmic reticulum stress and skin barrier dysfunction

The diabetes mellitus (DM) skin shows skin barrier dysfunction and skin lipid abnormality, similar to conditions induced by systemic or local glucocorticoid excess and aged skin. Inactive glucocorticoid (GC) is converted into active glucocorticoid by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). Hyperglycemia in DM and excessive GC are known to increase endoplasmic reticulum (ER) stress. We hypothesized that hyperglycemia affects systemic GC homeostasis and that the action of skin 11β-HSD1 and GC contributes to increased ER stress and barrier defects in DM. We compared 11β-HSD1, active GC, and ER stress between hyperglycemic and normoglycemic conditions in normal human keratinocytes and db/db mice. 11β-HSD1 and cortisol increased with time in keratinocyte culture under hyperglycemic conditions. 11β-HSD1 siRNA-transfected cells did not induce cortisol elevation in hyperglycemic condition. The production of 11β-HSD1 and cortisol was suppressed in cell culture treated with an ER stress-inhibitor. The 14-week-old db/db mice showed higher stratum corneum (SC) corticosterone, and skin 11β-HSD1 levels than 8-week-old db/db mice. Topical 11β-HSD1 inhibitor application in db/db mice decreased SC corticosterone levels and improved skin barrier function. Hyperglycemia in DM may affect systemic GC homeostasis, activate skin 11β-HSD1, and induce local GC excess, which increases ER stress and adversely affects skin barrier function.

In situ photo-crosslinking silk fibroin based hydrogel accelerates diabetic wound healing through antibacterial and antioxidant

Bacterial infection and excessive reactive oxygen species (ROS) in diabetic wounds lead to a prolonged inflammatory phase, and injuries are highly susceptible to developing into chronic wounds. Improving the poor microenvironment is vital to achieving effective diabetic wound healing. In this work, methacrylated silk fibroin (SFMA) was combined with ε-polylysine (EPL) and manganese dioxide nanoparticles (BMNPs) to form an SF@(EPL-BM) hydrogel with in situ forming, antibacterial and antioxidant properties. EPL imparted high antibacterial activity (>96 %) to the hydrogel. BMNPs and EPL showed good scavenging activity against a variety of free radicals. SF@(EPL-BM) hydrogel had low cytotoxicity and could alleviate H₂O₂-induced oxidative stress in L929 cells. In diabetic wounds infected with Staphylococcus aureus (S. aureus), the SF@(EPL-BM) hydrogel exhibited better antibacterial properties and reduced wound ROS levels more significantly than that of the control in vivo. In this process, the pro-inflammatory factor TNF-α was down-regulated, and the vascularization marker CD31 was up-regulated. H&E and Masson staining showed a rapid transition from the inflammatory to the proliferative phase of the wounds, with significant new tissue and collagen deposition. These results confirm that this multifunctional hydrogel dressing holds well potential for chronic wound healing.

Function and mechanism of mesenchymal stem cells in the healing of diabetic foot wounds

Diabetes has become a global public health problem. Diabetic foot is one of the most severe complications of diabetes, which often places a heavy economic burden on patients and seriously affects their quality of life. The current conventional treatment for the diabetic foot can only relieve the symptoms or delay the progression of the disease but cannot repair damaged blood vessels and nerves. An increasing number of studies have shown that mesenchymal stem cells (MSCs) can promote angiogenesis and re-epithelialization, participate in immune regulation, reduce inflammation, and finally repair diabetic foot ulcer (DFU), rendering it an effective means of treating diabetic foot disease. Currently, stem cells used in the treatment of diabetic foot are divided into two categories: autologous and allogeneic. They are mainly derived from the bone marrow, umbilical cord, adipose tissue, and placenta. MSCs from different sources have similar characteristics and subtle differences. Mastering their features to better select and use MSCs is the premise of improving the therapeutic effect of DFU. This article reviews the types and characteristics of MSCs and their molecular mechanisms and functions in treating DFU to provide innovative ideas for using MSCs to treat diabetic foot and promote wound healing.

Recent Advances in Nano-Drug Delivery Systems for the Treatment of Diabetic Wound Healing

Diabetes mellitus (DM) induced wound healing impairment remains a serious health problem and burden on the clinical obligation for high amputation rates. Based on the features of wound microenvironment, biomaterials loading specific drugs can benefit diabetic wound treatment. Drug delivery systems (DDSs) can carry diverse functional substances to the wound site. Nano-drug delivery systems (NDDSs), benefiting from their features related to nano size, overcome limitations of conventional DDSs application and are considered as a developing process in the wound treatment field. Recently, a number of finely designed nanocarriers efficiently loading various substances (bioactive and non-bioactive factors) have emerged to circumvent constraints faced by traditional DDSs. This review describes various recent advances of nano-drug delivery systems involved in mitigating diabetes mellitus-based non-healing wounds.

The Epidermal Keratinocyte as a Therapeutic Target for Management of Diabetic Wounds

Diabetes mellitus (DM) is an important cause of chronic wounds and non-traumatic amputation. The prevalence and number of cases of diabetic mellitus are increasing worldwide. Keratinocytes, the outermost layer of the epidermis, play an important role in wound healing. A high glucose environment may disrupt the physiologic functions of keratinocytes, resulting in prolonged inflammation, impaired proliferation, and the migration of keratinocytes and impaired angiogenesis. This review provides an overview of keratinocyte dysfunctions in a high glucose environment. Effective and safe therapeutic approaches for promoting diabetic wound healing can be developed if molecular mechanisms responsible for keratinocyte dysfunction in high glucose environments are elucidated.

Targeting matrix metalloproteases in diabetic wound healing

Chronic inflammation participates in the progression of multiple chronic diseases, including obesity, diabetes mellitus (DM), and DM related complications. Diabetic ulcer, characterized by chronic wounds that are recalcitrant to healing, is a serious complication of DM tremendously affecting the quality of life of patients and imposing a costly medical burden on society. Matrix metalloproteases (MMPs) are a family of zinc endopeptidases with the capacity of degrading all the components of the extracellular matrix, which play a pivotal part in healing process under various conditions including DM. During diabetic wound healing, the dynamic changes of MMPs in the serum, skin tissues, and wound fluid of patients are in connection with the degree of wound recovery, suggesting that MMPs can function as essential biomarkers for the diagnosis of diabetic ulcer. MMPs participate in various biological processes relevant to diabetic ulcer, such as ECM secretion, granulation tissue configuration, angiogenesis, collagen growth, re-epithelization, inflammatory response, as well as oxidative stress, thus, seeking and developing agents targeting MMPs has emerged as a potential way to treat diabetic ulcer. Natural products especially flavonoids, polysaccharides, alkaloids, polypeptides, and estrogens extracted from herbs, vegetables, as well as animals that have been extensively illustrated to treat diabetic ulcer through targeting MMPs-mediated signaling pathways, are discussed in this review and may contribute to the development of functional foods or drug candidates for diabetic ulcer therapy. This review highlights the regulation of MMPs in diabetic wound healing, and the potential therapeutic ability of natural products for diabetic wound healing by targeting MMPs.

Current and future outlook of loaded components in hydrogel composites for the treatment of chronic diabetic ulcers

Due to recalcitrant microangiopathy and chronic infection, traditional treatments do not easily produce satisfactory results for chronic diabetic ulcers. In recent years, due to the advantages of high biocompatibility and modifiability, an increasing number of hydrogel materials have been applied to the treatment of chronic wounds in diabetic patients. Research on composite hydrogels has received increasing attention since loading different components can greatly increase the ability of composite hydrogels to treat chronic diabetic wounds. This review summarizes and details a variety of newly loaded components currently used in hydrogel composites for the treatment of chronic diabetic ulcers, such as polymer/polysaccharides/organic chemicals, stem cells/exosomes/progenitor cells, chelating agents/metal ions, plant extracts, proteins (cytokines/peptides/enzymes) and nucleoside products, and medicines/drugs, to help researchers understand the characteristics of these components in the treatment of diabetic chronic wounds. This review also discusses a number of components that have not yet been applied but have the potential to be loaded into hydrogels, all of which play roles in the biomedical field and may become important loading components in the future. This review provides a "loading component shelf" for researchers of composite hydrogels and a theoretical basis for the future construction of "all-in-one" hydrogels.

Exploring the mechanism by which aqueous Gynura divaricata inhibits diabetic foot based on network pharmacology, molecular docking and experimental verification

BACKGROUND

To predict and validate the potential mechanism by which Gynura divaricata (GD) functions in the treatment of diabetic foot (DF).

METHODS

The main chemical constituents of GD were identified by reviewing the literature, the traditional Chinese medicine database platform (TCMIP) and the BATMAN-TCM platform. DF disease targets were identified with the GeneCards database, and the compound-target network was constructed by using the intersection of drugs and disease. The STRING platform was used to construct the protein-protein interaction (PPI) network, and Cytoscape 3.7.2 software was used to visualize the results. Moreover, the Metascape database was used for Gene Ontology (GO) enrichment analyses and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Molecular docking of the active ingredients of GD and core protein targets of DF was performed using AutoDock software. Finally, the predicted results were preliminarily verified with experiments.

RESULTS

A total of 140 potential targets of GD were identified and associated with DF. According to the PPI network analysis, GD accelerated DF wound healing, and the mechanism may be related to proteins such as AKT1, TP53, IL6, CASP3, TNF, and VEGFA. GO and KEGG enrichment analyses indicated that GD may play a role in the treatment of diabetic foot by affecting various signaling pathways. Molecular docking results showed that the proteins AKT1, TP53, IL6, CASP3, TNF, and VEGFA were closely associated with the components of GD. The animal experiments showed that GD reduced the levels of IL-6 and TNF-α and increased the mRNA and protein expression of VEGFA in rats with DF.

CONCLUSIONS

GD regulates multiple targets and multiple pathways to promote wound healing in DF.

Investigation of the keratinocyte transcriptome altered in high-glucose environment: An in-vitro model system for precision medicine

BACKGROUND

Impaired wound healing is a serious diabetes complication compromising patients' quality of life. However, the pathogenesis of diabetic wounds (DWs) remains incompletely understood. Human epidermal keratinocyte (HEK) is the sentinel cell that initiates healing processes after the epidermal integrity has been disrupted.

OBJECTIVE

This study aimed to investigate the functional roles of HEKs in wound healing and to identify candidate genes, signaling pathways and molecular signatures contributing to the DWs.

METHODS

HEKs were cultured in normal or high-glucose environment, followed by scratch, to mimic the microenvironment of normal wounds and DWs. Subsequently, we performed RNA sequencing and systematically analyzed the expression profiles by bioinformatics approaches.

RESULTS

High-glucose environment altered the keratinocyte transcriptome responses to wounding. In experimental model of DWs, we found that TNF, CYP24A1, NR4A3 and GGT1 were key overexpressed genes in keratinocytes and were implicated in multiple cellular responses. Further analysis showed that wounding in high-glucose environment activated G-protein-coupled receptor (GPCR) signaling, cAMP response element-binding protein (CREB) signaling, and adrenomedullin signaling in keratinocytes, while dysregulated skin development and immune responses as compared to their counterpart in normal glucose settings.

CONCLUSION

This simplified in-vitro model serves as a valuable tool to gain insights into the molecular basis of DWs and to facilitate establishment of personalized therapies in clinical practice.

Mapping intellectual structure and research hotspots in the field of fibroblast-associated DFUs: a bibliometric analysis

Background

Diabetic foot ulcers (DFUs) are one of the most popular and severe complications of diabetes. The persistent non-healing of DFUs may eventually contribute to severe complications such as amputation, which presents patients with significant physical and psychological challenges. Fibroblasts are critical cells in wound healing and perform essential roles in all phases of wound healing. In diabetic foot patients, the disruption of fibroblast function exacerbates the non-healing of the wound. This study aimed to summarize the hotspots and evaluate the global research trends on fibroblast-related DFUs through bibliometric analysis.

Methods

Scientific publications on the study of fibroblast-related DFUs from January 1, 2000 to April 27, 2022 were retrieved from the Web of Science Core Collection (WoSCC). Biblioshiny software was primarily performed for the visual analysis of the literature, CiteSpace software and VOSviewer software were used to validate the results.

Results

A total of 479 articles on fibroblast-related DFUs were retrieved. The most published countries, institutions, journals, and authors in this field were the USA, The Chinese University of Hong Kong, Wound Repair and Regeneration, and Seung-Kyu Han. In addition, keyword co-occurrence networks, historical direct citation networks, thematic map, and the trend topics map summarize the research hotspots and trends in this field.

Conclusion

Current studies indicated that research on fibroblast-related DFUs is attracting increasing concern and have clinical implications. The cellular and molecular mechanisms of the DFU pathophysiological process, the molecular mechanisms and therapeutic targets associated with DFUs angiogenesis, and the measures to promote DFUs wound healing are three worthy research hotspots in this field.

Pinoresinol stimulates keratinocyte proliferation and downregulates TNF-α secretion in peripheral blood mononuclear cells: An experimental in vitro study

Background and Aims

Natural coniferous resins are used in traditional medicine for the treatment of skin wounds. Coniferous wood resins ("callus" resin) are a mixture of abietic (resin) acids, lignans such as pinoresinol, and p-coumaric acid. The wound-healing properties of resins are thought to be related to their antimicrobial properties, but also to their effects on cell proliferation and inflammation. The purpose of this study was to identify and investigate the effects of novel aqueous dispersions of resin and its main components in the proliferation of human primary keratinocytes in vitro and in the expression of proinflammatory cytokines in human peripheral blood mononuclear cells.

Methods

The proliferation studies were performed under low and high calcium conditions with or without added growth stimulators at the time points of 2 and 6 days using AlamarBlue Cell Viability Reagent. The cytokine release assay was carried out by incubating the cells with the test articles for 18 h, after which the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and IL-8 were measured in the supernatant by enzyme-linked immunosorbent assay.

Results

Resin and the purified lignan PINO, but not p-coumaric acid or abietic acid (industrial tall oil rosin), enhanced the proliferation of human keratinocytes in vitro and inhibited the expression of TNF-α, and to a lesser extent the expression of IL-1β in peripheral blood mononuclear cells.

Conclusions

In this study, novel aqueous dispersions of spruce resin were used to investigate the effects of main resin components on keratinocyte proliferation and on the expression of key proinflammatory cytokines known to be associated with chronic wounds. The observations suggest that lignans, such as PINO, but not resin acids, are the components of resins that mediate the proliferative and TNF-α-suppressing effects. Lignans including PINO were identified as novel potential compounds in the treatment of chronic skin ulcers.

Hyperbaric oxygen therapy and chemokine administration - a combination with potential therapeutic value for treating diabetic wounds

Non-healing wounds impart serious medical problems to people with diabetes. Amongst 15% of diabetic patients, the incidence of foot ulcer is the most prevailing, which confers a significant risk of limb amputation, mainly due to hypoxia and impairment in cell signaling. Alteration in the expression of chemokines and the related factors in diabetic conditions delays the recruitment of different cell types, including fibroblasts, keratinocytes, and immune cells such as macrophages to the site of injury, further impairing neovasculogenesis, re-epithelialization, and extracellular matrix formation. Thus, proper activation of effector cells through an accurate signal pathway is necessary for better therapeutic application. Hyperbaric oxygen therapy (HBOT) is the current treatment prescribed by medical practitioners, shown to have increased the wound healing rate by reducing the need for significant amputation among the diabetic population. However, the risk of morbidity associated with HBOT needs complete attention through rigorous research to avoid adverse outcomes. Altering the level of pro-angiogenic chemokines may regulate the inflammatory response, further promote vascularization, and enhance the complete healing of wounds in diabetic patients. Thus, a combination of better therapeutic approaches could pave the way for developing a successful treatment for diabetic foot and wound healing.

Recent Advancement of Functional Hydrogels toward Diabetic Wound Management

Wound healing is a dynamic, orchestrated process comprising partially overlapping phases of hemostasis, inflammation, proliferation, and remodeling. This programmed process, dysregulated in diabetic individuals, results in chronic diabetic wounds. The normal process of healing halts at the inflammatory stage, and this prolonged inflammatory phase is characteristic of diabetic wounds. There are a few U.S. Food & Drug Administration approved skin substitutes; dermal matrixes are commercially available to manage diabetic wounds. However, expensiveness and nonresponsiveness in a few instances are the major limitations of such modalities. To address the issues, several treatment strategies have been exploited to treat chronic wounds; among them hydrogel-based systems showed promise due to favorable properties such as excellent absorption capabilities, porous structure, tunable mechanical strength, and biocompatibility. In the past two decades, hydrogels have become one of the most acceptable systems in the field of wound dressing material, offering single functionality to multifunctionality. This review focuses on the advancement of functional hydrogels explored for diabetic wound management. The process of diabetic wound healing is discussed in the light of the normal healing process, and the role of macrophages in the process is explained. This review also discusses the different approaches to treat diabetic wounds using functional hydrogels, along with their future opportunities.

High levels of TIMP1 are associated with increased extracellular matrix stiffness in isocitrate dehydrogenase 1-wild type gliomas

Glioma progression is accompanied with increased tumor tissue stiffness, yet the underlying mechanisms are unclear. Herein, we employed atomic force microscopy analysis to show that tissue stiffness was higher in isocitrate dehydrogenase (IDH)-wild type gliomas than IDH-mutant gliomas. Bioinformatic analyses revealed that tissue inhibitor of metalloproteinase-1 (TIMP1) was one of the preferentially upregulated genes in IDH-wild type gliomas as compared to IDH-mutant gliomas, and its higher expression indicated worse prognosis of glioma patients. TIMP1 intensity determined by immunofluorescence staining on glioma tissues positively correlated with glioma tissue stiffness. Mechanistically, TIMP1 expression was positively correlated with the gene expression of two predominant extracellular matrix components, tenascin C and fibronectin, both of which were also highly expressed in IDH-wild type gliomas. By introducing IDH1-R132H-containing vectors into human IDH1-wild type glioma cells to obtain an IDH1-mutant cell line, we found that IDH1 mutation increased the TIMP1 promoter methylation through methylation-specific PCR. More importantly, IDH1-R132H mutation decreased both the expression of TIMP1, fibronectin, tenascin C, and the tumor tissue stiffness in IDH1-mutant glioma xenografts in contrast to IDH1-wild type counterparts. Moreover, TIMP1 knockdown in IDH-wild type glioma cells inhibited the expression of tenascin C and fibronectin, and decreased tissue stiffness in intracranial glioma xenografts. Conclusively, we revealed an IDH mutation status-mediated mechanism in regulating glioma tissue stiffness through modulating TIMP1 and downstream extracellular matrix components.

Polydopamine-mediated graphene oxide and nanohydroxyapatite-incorporated conductive scaffold with an immunomodulatory ability accelerates periodontal bone regeneration in diabetes

Regenerating periodontal bone tissues in the aggravated inflammatory periodontal microenvironment under diabetic conditions is a great challenge. Here, a polydopamine-mediated graphene oxide (PGO) and hydroxyapatite nanoparticle (PHA)-incorporated conductive alginate/gelatin (AG) scaffold is developed to accelerate periodontal bone regeneration by modulating the diabetic inflammatory microenvironment. PHA confers the scaffold with osteoinductivity and PGO provides a conductive pathway for the scaffold. The conductive scaffold promotes bone regeneration by transferring endogenous electrical signals to cells and activating Ca²⁺ channels. Moreover, the scaffold with polydopamine-mediated nanomaterials has a reactive oxygen species (ROS)-scavenging ability and anti-inflammatory activity. It also exhibits an immunomodulatory ability that suppresses M1 macrophage polarization and activates M2 macrophages to secrete osteogenesis-related cytokines by mediating glycolytic and RhoA/ROCK pathways in macrophages. The scaffold induces excellent bone regeneration in periodontal bone defects of diabetic rats because of the synergistic effects of good conductive, ROS-scavenging, anti-inflammatory, and immunomodulatory abilities. This study provides fundamental insights into the synergistical effects of conductivity, osteoinductivity, and immunomodulatory abilities on bone regeneration and offers a novel strategy to design immunomodulatory biomaterials for treatment of immune-related diseases and tissue regeneration.

•

The conductive PGO-PHA-AG scaffold can activate Ca²⁺ channels.

•The PGO-PHA-AG scaffold had ROS-scavenging and anti-inflammatory activities.

•The scaffold exhibited an immunomodulatory ability.

•The scaffold induced excellent periodontal bone regeneration in diabetes.

Promoting Re-epithelialization in an oxidative diabetic wound microenvironment using self-assembly of a ROS-responsive polymer and P311 peptide micelles

Engineering smart nano-therapeutics for re-epithelialisation of chronic wounds facilitates the wound healing process. However, due to excessive oxidative stress damage and persistent inflammation in diabetic wound microenvironment, the migration of stimulating epidermal cells in diabetic wounds represents a significant challenge. Here we synthesised P311-loaded micelles by self-assembly of P311 peptides and diblock copolymer poly (ethylene glycol)-block-poly (propylene sulfide) (PEG-b-PPS, denoted as PEPS) that have unique ability to transform an oxidative wound microenvironment into a proregenerative one while also providing cues for epidermal cell migration. The P311@PEPS showed an accelerated migration of epidermal cells via activation of the Akt signalling pathway, simultaneously suppressing the unfavourable oxidative wound microenvironment by scavenging reactive oxygen species (ROS), ultimately leading to the induction of an environment conducive to cell migration. Furthermore, the micelles were able to bypass the inhibitory effect of ROS on the Akt signalling pathway, thereby promoting epidermal cell migration. Additionally, we observed that diabetic wounds treated with P311@PEPS showed accelerated chronic wound healing, granulation tissue formation, collagen deposition and re-epithelialisation, thereby suggesting the efficacy of P311@PEPS as a promising nanoplatform for the treatment of chronic wounds. STATEMENT OF SIGNIFICANCE: Based on the unique conditions of the diabetic wound microenvironment, a smart drug delivery system with ROS-responsive nanomaterials has been widely investigated to enhance diabetic wound healing. In our previous studies, we observed that P311 promotes epidermal cell migration to induce wound re-epithelialisation. However, the application of P311 suffers from its instability. Herein, we developed a therapeutic platform with P311-loaded micelles (P311@PEPS), which were synthesized by the self-assembly of P311 peptides and diblock copolymer poly (ethylene glycol)-block-poly (propylene sulfide) (PEG-b-PPS, denoted as PEPS). These micelles provide continuous migration signals for epidermal cells by ROS-trigged P311 release. Additionally, P311@PEPS scavenges excess ROS and provides a microenvironment that reduces inflammation, which could protect P311 from enzymatic degradation and improve the bioavailability of P311.

New Horizons of Macrophage Immunomodulation in the Healing of Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) are one of the most costly and troublesome complications of diabetes mellitus. The wound chronicity of DFUs remains the main challenge in the current and future treatment of this condition. Persistent inflammation results in chronic wounds characterized by dysregulation of immune cells, such as M1 macrophages, and impairs the polarization of M2 macrophages and the subsequent healing process of DFUs. The interactive regulation of M1 and M2 macrophages during DFU healing is critical and seems manageable. This review details how cytokines and signalling pathways are co-ordinately regulated to control the functions of M1 and M2 macrophages in normal wound repair. DFUs are defective in the M1-to-M2 transition, which halts the whole wound-healing machinery. Many pre-clinical and clinical innovative approaches, including the application of topical insulin, CCL chemokines, micro RNAs, stem cells, stem-cell-derived exosomes, skin substitutes, antioxidants, and the most recent Phase III-approved ON101 topical cream, have been shown to modulate the activity of M1 and M2 macrophages in DFUs. ON101, the newest clinically approved product in this setting, is designed specifically to down-regulate M1 macrophages and further modulate the wound microenvironment to favour M2 emergence and expansion. Finally, the recent evolution of macrophage modulation therapies and techniques will improve the effectiveness of the treatment of diverse DFUs.

Photocatalytic glucose depletion and hydrogen generation for diabetic wound healing

High-glucose microenvironment in the diabetic foot ulcer (DFU) causes excessive glycation and induces chronic inflammation, leading to the difficulty of DFU healing. Hydrogen-rich water bath can promote the healing of DFU in clinic by virtue of the anti-inflammatory effect of hydrogen molecules, but the long-term daily soaking counts against the formation of a scab and cannot change the high-glucose microenvironment, limiting the outcome of DFU therapy. In this work, photocatalytic therapy of diabetic wound is proposed for sustainable hydrogen generation and local glucose depletion by utilizing glucose in the high-glucose microenvironment as a sacrificial agent. Hydrogen-incorporated titanium oxide nanorods are developed to realize efficient visible light (VIS)-responsive photocatalysis for glucose depletion and hydrogen generation, achieving a high efficacy of diabetic wound healing. Mechanistically, local glucose depletion and hydrogen generation jointly attenuate the apoptosis of skin cells and promote their proliferation and migration by inhibiting the synthesis of advanced glycation end products and the expression of their receptors, respectively. The proposed VIS-photocatalytic strategy provides a solution for facile, safe and efficient treatment of DFU.

Hydrogenation is a treatment for chronic inflammation caused by high glucose levels in diabetic ulcers, However, current therapies have limitations. Here, the authors report on the creation of a visible light photocatalytic agent which depletes glucose in the wound and generates hydrogen to aid in diabetic wound healing.

Macrophages as a therapeutic target to promote diabetic wound healing

It is well‏ ‏established that macrophages are key regulators of wound healing, displaying impressive plasticity and an evolving phenotype, from an aggressive pro-inflammatory or "M1" phenotype to a pro-healing or "M2" phenotype, depending on the wound healing stage, to ensure proper healing. Because dysregulated macrophage responses have been linked to impaired healing of diabetic wounds, macrophages are being considered as a therapeutic target for improved wound healing. In this review, we first discuss the role of macrophages in a normal skin wound healing process and discuss the aberrations that occur in macrophages under diabetic conditions. Next we provide an overview of recent macrophage-based therapeutic approaches, including delivery of ex-vivo-activated macrophages and delivery of pharmacological strategies aimed at eliminating or re-educating local skin macrophages. In particular, we focus on strategies to silence key regulator genes to repolarize wound macrophages to the M2 phenotype, and we provide a discussion of their potential future clinical translation.

Stem Cell-Based Therapeutic Strategies in Diabetic Wound Healing

Impaired wound healing and especially the “all-too-common” occurrence of associated diabetic foot ulcers (DFU) are becoming an increasingly urgent and deteriorating healthcare issue, which drastically impact the quality of life and further heighten the risks of infection and amputation in patients with diabetes mellitus. Amongst the multifactorial wound healing determinants, glycemic dysregulation has been identified to be the primary casual factor of poor wound healing. Unfortunately, current therapeutic modalities merely serve as moderate symptomatic relieves but often fail to completely restore the wound site to its pre-injury state and prevent further recurrence. Stem cell-based therapeutics have been employed for its promising potential to address the root of the problem as they not only exhibit the capacity for self-renewal and differentiation towards multiple lineages, but also have been disclosed to participate in mediating variant growth factors and cytokines. Herein we review the current literatures on the therapeutic benefits of using various kinds of stem cells, including embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), mesenchymal stem cells (MSCs), and adipose-derived stem cells (ASCs) in diabetic wound healing by searching on the PubMed® Database for publications. This study shall serve as an overview of the current body of research with particular focus on autologous ASCs and the laboratory expandable iPSCs in hope of shedding more light on this attractive therapy so as to elevate the efficacy of wound healing that is almost always compromised in diabetic patients.