Macrophage polarization in diabetic wound healing

Naringenin-loaded SBMA/GelMA hydrogel: Restoring immune balance and promoting angiogenesis via the PPARα/STING pathway in diabetic wounds

The impaired wound-healing process in diabetic patients poses a significant clinical challenge due to local immune dysregulation and impaired angiogenesis. This study introduces a novel therapeutic approach using an SBMA/GelMA hydrogel loaded with naringenin (NRN) to restore the immune environment and promote angiogenesis in diabetic wounds. The hydrogel, synthesized via photo-crosslinking, exhibits excellent biocompatibility and inherent antibacterial properties, creating an optimal environment for wound healing. By incorporating NRN, a natural compound with therapeutic potential, the hydrogel enables sustained and controlled release of NRN, ensuring prolonged therapeutic effects. In vitro studies showed that the NRN-loaded SBMA/GelMA hydrogel effectively activated PPARα, suppressing the Sting pathway. This led to enhanced M2 macrophage polarization and increased angiogenesis. In vivo experiments with diabetic wound models further validated the hydrogel's therapeutic potential. The hydrogel significantly accelerated wound healing, evidenced by reduced wound size, enhanced re-epithelialization, and increased angiogenesis. Immunohistochemical analysis demonstrated a shift towards an anti-inflammatory M2 macrophage phenotype within the wound microenvironment. This study provides valuable insights into the mechanisms of wound healing in diabetic conditions and offers new avenues for developing advanced materials for diabetic wound management.

Natural, safety immunomodulatory derivatives of lactobacillus biofilms promote diabetic wound healing by metabolically regulating macrophage phenotype and alleviating local inflammation

INTRODUCTION

Long-term inflammatory microenvironment further impairs the healing process of diabetic wounds. Many studies have shown that Lactobacillus can regulate immune function and promote injured tissue repair. However, the immunomodulatory function and safety of Lactobacillus biofilm (LB) on wounds need further investigation.

OBJECTIVES

In this present research, we proposed a "bacteria-free biofilm derivative therapy" and successfully extracted Lactobacillus biofilm derivatives (LBDs) by ultrasonic separation and filtration technology for the natural and safe treatment of diabetic wounds.

METHODS

The study first cultured Lactobacillus anaerobically and extracted LBDs using ultrasound separation combined with filtration technology. LBDs were characterized via scanning electron microscopy, Concanavalin A fluorescence staining, and protein gel electrophoresis. In vivo diabetic wound model, wound closure rates were dynamically monitored, and tissue sections were analyzed using hematoxylin-eosin and immunofluorescence staining to evaluate LBDs' healing effects. An in vitro macrophage inflammation model was established, employing immunofluorescence, flow cytometry, and Western blotting techniques to explore the molecular mechanisms underlying LBDs' effects on macrophage phenotypes. Furthermore, whole-genome sequencing and proteomics of LBDs-treated macrophages were performed to further elucidate the intrinsic molecular mechanisms through which LBDs regulate macrophage phenotypes.

RESULTS

LBDs were effectively extracted utilizing ultrasonic separation coupled with filtration technology. Studies revealed that LBDs modulate the systemic metabolic reprogramming in wound-site macrophages, suppress JAK-STAT1 signaling pathway, alleviate the local inflammatory microenvironment, promote neovascularization and ultimately accelerate wound healing.

CONCLUSION

The LBDs retains most bioactive components of the LB. As a natural, safe and immunomodulatory agent, LBDs promote diabetic wound healing by metabolically reprogramming macrophage phenotypes and improving the local immune microenvironment, offering promising potential for regenerative applications in diabetic wound management.

Exosome-like vesicles encapsulated with specific microRNAs accelerate burn wound healing and ameliorate scarring

Burn injuries are prevalent, yet effective treatments remain elusive. Exosomes derived from mesenchymal stem cells (MSC-Ex) possess remarkable pro-regenerative properties for wound healing. Despite their potential, the challenge of mass production limits their clinical application. To address this, preparing exosome-like vesicles has become an international trend. In this study, 28 key microRNAs (miRNAs) with significant pro-proliferation, anti-inflammation, and anti-fibrosis functions were screened from MSC-Ex. These miRNAs were encapsulated into liposomes and then hybridized with extracellular vesicles derived from watermelon to create synthetic exosome-like vesicles. The fabricated vesicles exhibited similar particle size and zeta potential to MSC-Ex, demonstrating high serum stability and effectively resisting the degradation of miRNA by RNase. They were efficiently internalized by cells and enabled a high rate of lysosomal escape for miRNAs post cellular uptake, thereby effectively exerting their pro-proliferative, anti-inflammatory, and anti-fibrotic functions. Further experiments demonstrated that these vesicles efficiently accelerated burn wound healing and reduced scarring, with effects comparable to those of natural MSC-Ex. Based on these findings, the exosome-like vesicles fabricated in this study present a promising alternative to MSC-Ex in burn wound treatment.

Injectable DMM/GelMA hydrogel for diabetic wound healing via regulating mitochondrial metabolism and macrophage repolarization

The chronic diabetic wounds represented by diabetes foot ulcers (DFUs) are a worldwide challenge. Excessive production of reactive oxygen species (ROS) and persistent inflammation caused by the impaired phenotype switch of macrophages from M1 to M2 during wound healing are the main culprits of non-healing diabetic wounds. Therefore, an injectable DMM/GelMA hydrogel as a promising wound dressing was designed to regulate the mitochondrial metabolism of macrophages via inhibiting succinate dehydrogenase (SDH) activity and to promote macrophage repolarization towards M2 type. DMM/GelMA hydrogel exhibited good biocompatibility, injectability and water absorption and retention capacity. In vitro studies showed that DMM/GelMA hydrogel inhibited SDH activity, recovered the decrease in mitochondrial membrane potential, and significantly reduced the production of ROS and inflammatory cytokines in the LPS-evoked macrophages. In vivo evaluations and RNA sequencing analysis demonstrated that DMM/GelMA hydrogel downregulated ROS generation, the ratio of M1/M2 macrophages and pro-inflammatory cytokine production in the full-thickness skin wound model in the diabetic mice. Additionally, DMM/GelMA hydrogel improved the wound-healing quality with thicker epidermis, more collagen deposition and higher ratio of collagen I/III by sustained release of DMM. These findings indicate this hydrogel has a great potential to be a biocompatible, injectable and anti-inflammatory dressing for better diabetic wound healing.

A Smart MMP-9-responsive Hydrogel Releasing M2 Macrophage-derived Exosomes for Diabetic Wound Healing

Chronic diabetic wounds are characterized by prolonged inflammation and excessive accumulation of M1 macrophages, which impede the healing process. Therefore, resolving inflammation promptly and transitioning to the proliferative phase are critical steps for effective diabetic wound healing. Exosomes have emerged as a promising therapeutic strategy. In this study, a smart hydrogel capable of responding to pathological cues in the inflammatory microenvironment to promote the transition from inflammation to proliferation by delivering M2 macrophage-derived exosomes (M2-Exos) is developed. The smart hydrogel is synthesized through the cross-linking of oxidized dextran, a matrix metalloproteinase (MMP)-9-sensitive peptide, and carboxymethyl chitosan containing M2-Exos. In response to elevated MMP-9 concentrations in the inflammatory microenvironment, the hydrogel demonstrates diagnostic logic, adjusting the release kinetics of M2-Exos accordingly. The on-demand release of M2-Exos facilitated macrophage polarization from the M1 to the M2 phenotype, thereby promoting the transition from the inflammatory to the proliferative phase and accelerating diabetic wound healing. The transcriptomic analysis further reveals that the MMP-9-responsive hydrogel with M2-Exos delivery exerts anti-inflammatory and regenerative effects by downregulating inflammation-related pathways. This study introduces an innovative, microenvironment-responsive exosome delivery system that enables precise control of therapeutic agent release, offering a personalized approach for the treatment of chronic diabetic wounds.

USP7 deficiency promotes diabetic wound healing by repressing GATA3-mediated pro-inflammatory macrophage polarization

BACKGROUND

The polarization of inflammatory macrophages is an important factor contributing to delay wound healing in diabetic foot ulcers (DFU). In this study, the role of ubiquitin-specific protease 7 (USP7) in regulating macrophage polarization during DFU progression was investigated.

METHODS

Gene and protein expression levels were assessed using qRT-PCR and western blot. In vitro and in vivo diabetes mellitus (DM) models were established by HG treatment and STZ injection, respectively. HUVEC viability, migration, and angiogenesis were detected by CCK8 assay, wound healing assay, and tube formation assay, respectively. Flow cytometry was employed to analyze the levels of macrophage polarization markers. Co-IP assay was performed to analyze the interaction between USP7 and GATA3.

RESULTS

Our results demonstrated that USP7 was overexpressed in ulcer margin tissues of DFU patients, wound tissues of DFU mice, and HG-treated macrophages. Functionally, USP7 deficiency inhibited macrophage M1 polarization and promoted wound healing in DFU mice. In vitro, USP7 knockdown promoted HUVEC proliferation, migration, and angiogenesis by inducing M2 macrophage polarization and inhibiting M1 macrophage polarization under HG condition. Mechanistically, USP7 could stabilize GATA3 protein in macrophages by deubiquitinating GATA3. Moreover, the effects of USP7 knockdown on HUVEC function and macrophage polarization under HG condition were partially reversed by GATA3 overexpression.

CONCLUSION

USP7 silencing enhanced wound healing in DFU by inhibiting M1 macrophage polarization and promoting M2 macrophage polarization through mediating GATA3 deubiquitylation.

An injectable and adaptable system for the sustained release of hydrogen sulfide for targeted diabetic wound therapy by improving the microenvironment of inflammation regulation and angiogenesis

The combined effects of persistent chronic inflammation, oxidative stress, microcirculation disorders, and dysregulated cellular energy metabolism often hinder the repair of diabetic skin wounds. Traditional treatment methods are typically insufficient in simultaneously addressing these complex factors, resulting in delayed wound healing and a high propensity for recurrence and chronic ulceration. This study developed an innovative strategy based on reactive oxygen species (ROS)-responsive nanoparticles loaded with an ultraviolet (UV)-light-responsive hydrogen sulfide (H2S) donor. This approach leverages the endogenous ROS present in diabetic wounds and external UV light as dual triggers to facilitate the controlled and stepwise release of H2S. The material design explicitly targets the critical challenges in diabetic wound repair, including the inhibition of chronic inflammation, oxidative stress reduction, microcirculation improvement, and support of cellular energy metabolism, thereby significantly accelerating wound healing. This adaptive release of signaling molecules effectively modulates the wound regeneration microenvironment, enhancing the repair process and offering a promising solution for diabetic skin wound management. STATEMENT OF SIGNIFICANCE: This study developed an innovative strategy based on reactive oxygen species (ROS)-responsive nanoparticles loaded with an ultraviolet (UV)-light-responsive hydrogen sulfide (H2S) donor. This approach leverages the endogenous ROS present in diabetic wounds and external UV light as dual triggers to facilitate the controlled and stepwise release of H2S. The material design explicitly targets the critical challenges in diabetic wound repair, including the inhibition of chronic inflammation, oxidative stress reduction, microcirculation improvement, and support of cellular energy metabolism, thereby significantly accelerating wound healing. This adaptive release of signaling molecules effectively modulates the wound regeneration microenvironment, enhancing the repair process and offering a promising solution for diabetic skin wound management.

Sulforaphane promotes diabetic wound healing by regulating macrophage efferocytosis and polarization

BACKGROUND

Delayed wound healing frequently occurs as a complication of diabetes. Diabetic wounds that are difficult to heal are associated with chronic, persistent inflammation, characterized by impaired efferocytosis and a sustained pro-inflammatory state of macrophages at the wound site. Sulforaphane (SFN), a bioactive compound found in cruciferous vegetables, possesses anti-inflammatory and antioxidant activities. Numerous studies have shown that SFN can inhibit various inflammatory diseases such as atherosclerosis and psoriasis; however, its potential in treating diabetic wounds remains unknown.

PURPOSE

This study investigates the effects and potential mechanisms of SFN on diabetic wound healing.

METHODS

Network pharmacology approaches were employed to identify potential targets of SFN for diabetic wound treatment. Additionally, an STZ-induced diabetic mouse model (C57/B6) was used in in vivo studies to examine SFN's impact on diabetic wound healing. Simultaneously, immunofluorescence staining, immunohistochemical staining, Western blotting, and qPCR analysis were employed to detect phenotypes associated with macrophage efferocytosis and M2 polarization. Subsequently, the mechanism underlying SFN treatment was explored through in vitro experiments utilizing the THP-1 human monocyte cell line.

RESULTS

The results demonstrated that topical SFN application accelerated wound healing in diabetic mice, partly through the enhancement of impaired macrophage efferocytosis and the promotion of M2 macrophage polarization, thereby reducing the inflammatory response at the wound site. SFN promoted the phagocytosis of apoptotic Jurkat cells by THP-1 differentiated macrophages, reducing the resulting inflammatory response. Mechanistic studies revealed that SFN promotes macrophage efferocytosis by activating nuclear factor E2-related factor 2 (Nrf2), leading to upregulation of heme oxygenase 1 (HO-1) expression and subsequent enhancement of mer proto-oncogene tyrosine kinase (MERTK), a recognition receptor for efferocytosis. Furthermore, SFN enhanced macrophage polarization toward the M2 phenotype and reduced the lipopolysaccharide (LPS)-induced inflammatory response in vitro.

CONCLUSION

These data suggest that SFN could serve as an effective adjunct or novel therapeutic agent for treating chronic non-healing wounds in diabetes.

STING coordinates resolution of inflammation during wound repair by modulating macrophage trafficking through STAT3

Efficient cutaneous wound healing requires a coordinated transition between inflammatory phases mediated by dynamic changes in leukocyte subset populations. Here, we identify STING as a key innate immune mediator governing timely resolution of inflammation by regulating macrophage dynamics during skin repair. Using a mouse model, we show STING deficiency caused delayed wound closure associated with abnormal persistence of TNF-α+ leukocytes. This resulted from the impaired macrophage recruitment. STING controlled the trafficking of bone marrow myeloid cells into blood and wounds, intrinsically enhancing macrophage migratory capacity through STAT3 activation. Specifically, STING modulated the production of monocyte chemokines and their receptors CCR2/CCR5 to enable efficient egress and wound infiltration. Consequently, disrupted systemic and local STING-STAT3-chemokine signaling combine to delay macrophage influx. This study elucidates STING as a critical rheostat tuning macrophage responses through STAT3 to orchestrate inflammatory resolution necessary for efficient wound healing. Our findings have broad implications for targeting STING therapeutically in both regenerative medicine and inflammatory disease contexts.

miR-874-3p Alleviates Macrophage-Mediated Inflammatory Injury in Intracerebral Hemorrhage by Targeting HIPK2

Macrophages mediate secondary inflammatory injury after intracerebral hemorrhage (ICH). This study aimed to investigate the role and molecular mechanisms of miR-874-3p in macrophage polarization. A mice model of ICH was constructed by autologous blood injection. Macrophages were treated with erythrocyte lysates to construct an ICH cell model. Real-time quantitative reverse transcription PCR (RT-qPCR) was used to detect miR-874-3p levels. Enzyme-Linked Immunosorbent Assay (ELISA) was used to detect macrophage polarization markers. Brain tissue water content and neurological deficit scores were used to assess the degree of inflammatory injury in ICH mice. RNA immunoprecipitation (RIP) and Dual-luciferase reporter (DLR) assays were used to analyze the targeting relationship between miR-874-3p and target mRNA. miR-874-3p levels were decreased in ICH mice and erythrocyte lysates-treated macrophages. miR-874-3p mimic alleviated inflammatory injury, decreased the levels of M1 macrophage markers, and increased the levels of M2 macrophage markers, suggesting that miR-874-3p is involved in ICH by regulating macrophage polarization. HIPK2 is the target mRNA of miR-874-3p and has the opposite expression pattern of miR-874-3p. Overexpression of HIPK2 attenuates the effect of elevated miR-874-3p levels on macrophage polarization and inflammatory brain injury in ICH mice. miR-874-3p regulates macrophage polarization in ICH by targeting HIPK2. Therefore, the miR-874-3p/HIPK2 axis may be a promising target for ICH treatment.

Multifunctional Bioactive Nanozyme Systems for Enhanced Diabetic Wound Healing

The protracted transition from inflammation to proliferation in diabetic wound healing poses significant challenges, exacerbated by persistent inflammatory responses and inadequate vascularization. To address these issues, a novel nanozymatic therapeutic approach utilizing asymmetrically structured MnO₂-Au-mSiO₂@aFGF Janus nanoparticles is engineered. Nanozymes featuring a mSiO₂ head and MnO₂ extensions, into which acidic fibroblast growth factor (aFGF) is encapsulated, resulting in MnO₂-Au-mSiO₂@aFGF Janus nanoparticles (mSAM@aFGF), are synthesized. This nanozyme system effectively emulates enzymatic activities of catalase (CAT) and superoxide dismutase (SOD), catalyzing degradation of reactive oxygen species (ROS) and generating oxygen. In addition, controlled release of aFGF fosters tissue regeneration and vascularization. In vitro studies demonstrate that mSAM@aFGF significantly alleviates oxidative stress in cells, and enhances cell proliferation, migration, and angiogenesis. An injectable hydrogel based on photocrosslinked hyaluronic acid (HAMA), incorporating the nanozymatic ROS-scavenging and growth factor-releasing system, is developed. The HAMA-mSAM@aFGF hydrogel exhibits multifaceted benefits in a diabetic wound model, including injectability, wound adhesion, hemostasis, anti-inflammatory effects, macrophage polarization from M1 to M2 phenotype, and promotion of vascularization. These attributes underscore the potential of this system to facilitate transition from chronic inflammation to the proliferative phase of wound repair, offering a promising therapeutic strategy for diabetic wound management.

Therapeutic potential of microalgae-derived natural compounds in diabetic wound healing: A comprehensive review

A variety of cell types and chemical systems are known to interact throughout the complex process of wound healing. In addition to being very uncomfortable for patients, wounds that do not heal properly or become chronic can place a heavy burden on society. The creation of novel treatment approaches can expedite the healing process, reduce the societal burden, and improve patient outcomes. Due to advancements in the field of biomedical science, microalgae have significant potential for use in diabetic wound healing and other wound healing applications. This review delves into the physiological process of wound healing, the use of microalgae in wound healing, and a detailed explanation of the wound healing roles of various microalgal originated bioactive compounds including alginate, pigments, fatty acids, proteins, polysaccharides, flavonoids and phenols. The study discusses the efficacy of photosynthetic hydrogels in drugs and oxygen delivery to the wounded area that is crucial for promoting a good healing process, as well as highlights the drawbacks and challenges involved in using microalgae for wound healing. Given the current state of the art in utilizing microalgae for wound care, this review provides new perspectives for further research, along with insightful advice and innovative suggestions for academics engaged in this area.

Injectable polypeptide/chitosan hydrogel with loaded stem cells and rapid gelation promoting angiogenesis for diabetic wound healing

Diabetic wounds face challenges like infection, prolonged inflammation, and poor vascularization. To address these, we developed an injectable hydrogel for diabetic wound dressing by grafting palmitoyl tetrapeptide-7 (Pal-7) onto chitosan (CS) to form CS/Pal-7 (CP7). Glutaraldehyde (GA) was used to enhance crosslinking between CS, creating the CP7 hydrogel. The hydrogel showed rapid gelation, good mechanical properties, biocompatibility, and strong antibacterial effects. Additionally, stem cells derived from human deciduous teeth (SHED) were loaded into the CP7 hydrogel to form SHED@CP7. This complex promoted human umbilical vein endothelial cell (HUVEC) migration and tube formation, aiding angiogenesis, and induced macrophage polarization toward the M2 phenotype, exerting anti-inflammatory effects. In streptozotocin-induced diabetic mouse wounds, SHED@CP7 significantly improved wound healing with over 95 % wound closure, increased collagen deposition, and reduced tumor necrosis factor-α (TNF-α) expression by approximately 75 % and Interleukin-6 (IL-6) expression by around 81 %. It also increased Interleukin-10 (IL-10) expression by approximately 58 %, modulating the inflammatory microenvironment for regeneration. Moreover, SHED@CP7 enhanced angiogenesis, as shown by a 69 % increase in endothelial cell marker CD31 staining, supporting faster wound healing. These results highlight the potential of SHED@CP7 as an effective treatment for diabetic wounds.

Bone Morphogenetic Protein 7 Improves Wound Healing in Diabetes by Decreasing Inflammation and Promoting M2 Macrophage Polarization

Diabetic foot ulcers (DFUs) are a devastating complication of diabetes, presenting limited treatment success rates due to their complex pathophysiology. Bone morphogenetic protein 7 (BMP7) confers tissue protective and regenerative functions, but its potential role in diabetic wound healing is unknown. The aim of this study was to investigate the effects of topical BMP7 treatment in wound healing using a streptozotocin-induced diabetic mouse model. The expression of markers of wound healing progression were detected using RT-PCR or immunohistochemistry. Overall, BMP7 improved wound closure, as well as maturation of granulation tissue and collagen deposition, as evidenced by hematoxylin and eosin and Masson's trichrome histological analysis. The expression of inflammatory markers (IL-6, TNF-α) and matrix metalloproteinase-9 were decreased in BMP7-treated wounds, together with the number of pro-inflammatory M1 macrophages and T lymphocytes. The number of anti-inflammatory M2 macrophages was increased in BMP7-treated wounds. Moreover, BMP7 decreased oxidative stress and increased Ki67+ cells and CD31+ cells, indicating induced proliferation and angiogenesis in the wound bed compared to the control wounds. Finally, BMP7 activated the ERK pathway and suppressed the p38 pathway in diabetic wounds. Together, our data suggest that BMP7 enhanced skin wound healing in diabetes by decreasing local inflammation and oxidative stress, which promoted a regenerative environment for collagen deposition, wound maturation, cell proliferation, and angiogenesis. These findings underline BMP7 as a potential therapeutic agent for the treatment of skin wounds in diabetes.

Uncovering Sex-Related Differences in Skin Macrophage Polarization During Wound Healing in Diabetic Mice

BACKGROUND

Chronic wounds, such as diabetes-related foot ulcers, arise from delayed wound healing and create significant health and economic burdens. Macrophages regulate healing by shifting between pro- and anti-inflammatory phenotypes, known as macrophage polarization. Sex and diabetes can impair wound healing, but their influence on macrophage phenotype in skin tissue during wound healing remains unclear, which was investigated in this study using a novel two-sex diabetic mouse model.

METHODS

Diabetes was induced in male and female C57BL/6J mice using low-dose streptozotocin injections and high-fat diet feeding, with chow-fed mice as controls. After 18 weeks, each mouse received four circular full-thickness dorsal skin wounds. The macrophage phenotypes in wounded skin tissues at Day 0 and Day 10 post-wounding were analyzed using mass cytometry with manual gating and automated computational clustering.

RESULTS

Male diabetic mice exhibited more severe hyperglycemia and insulin resistance compared to females. Although diabetic mice did not display delayed wound healing, male mice had a greater proportion of total macrophages than females, especially a higher proportion of pro-inflammatory matrix metalloproteinase-9 (MMP-9)+ macrophages and a lower proportion of anti-inflammatory adiponectin receptor 1 (AdipoR1)+ macrophages in male diabetic mice compared to females, indicating an imbalanced polarization towards a pro-inflammatory phenotype that could result in poorer wound healing. Interestingly, computational clustering identified a new pro-inflammatory, pro-healing phenotype (Ly6C+AdipoR1+CD163-CD206-) more abundant in females than males, suggesting this phenotype may play a role in the transition from the inflammatory to the proliferative stage of wound healing.

CONCLUSIONS

This study demonstrated a significant sex-based difference in macrophage populations, with male diabetic mice showing a pro-inflammatory bias that may impair wound healing, while a unique pro-inflammatory, pro-healing macrophage population more abundant in females could facilitate recovery. Further research is needed to investigate the role of these newly identified phenotypes in regulating impaired wound healing.

Thermosensitive, injectable, antibacterial glabridin liposome/chitosan dual network hydrogel for diabetic wound healing

Thermosensitive hydrogels show great potential in healing diabetic wounds, but they are still challenged by the long healing time, risk of infectivity, and accumulation of melanin. Herein, a dual network hydrogel is designed, which consists of chlorogenic acid (CA) modified chitosan (CS) (CA@CS), poly(N-isopropylacrylamide) (PNIPAm), and glabridin liposomes (GL). The gelation transition temperature of the hydrogel is 32-34 °C, which thus endows it with superior injectability at ambient temperature. Moreover, GL/PNIPAm/CA@CS also exhibits excellent biocompatibility, and can promote the growth of epidermal cells, and the healing of diabetic wounds. GL/PNIPAm/CA@CS can also control the immune reactions by enhancing the release of CD206, and decreasing the formation of CD86 and ROS, which further promotes the production of CD31 and VEGF, and reduces the expression of pro-inflammatory factors, thus aiding in the healing of diabetic wounds. Furthermore, GL/PNIPAm/CA@CS can also suppress the growth bacterial, which can thus decrease the wound microbiota levels and facilitate the recovery of diabetic wounds. More importantly, it can reduce melanin production by 80 % due to the action of glabridin. Consequently, GL/PNIPAm/CA@CS shows significant promise in enhancing the wound healing in future and decreasing the accumulation of melanin.

Antibacterial betaine modified chitosan-based hydrogel with angiogenic property for photothermal enhanced diabetic wound repairing

Chronic diabetes wound repairing is still a huge challenge in clinical practice. High concentration of reactive oxygen species and vascular disfunction are the main factors hindering the recovery of diabetes wounds. This research grafted betaine onto chitosan (CSBT) to enhance the antibacterial property and the CSBT was cross-linked with PEO90 dialdehyde (PEO DA) to prepare hydrogel with Ca2+ loading to promote the coagulation. The polydopamine nanoparticles (PDA NPs) with photothermal property and antioxidant property was composited to the hydrogel and deferoxamine (DFO) was loaded to fabricate the multifunctional CBPCa/PDA/DFO hydrogel to promote vascular regeneration in combination with photothermal antibacterial performance for the diabetes wounds treatment. The CBPCa/PDA/DFO hydrogel showed good mechanical strength, injectability, anti-inflammatory property and coagulation performance. Furthermore, the antibacterial effect of chitosan based hydrogel was enhanced with near infrared (NIR) stimulated photothermal treatment. Combined with the photothermal effect and the angiogenic drug DFO release, the CBPCa/PDA/DFO hydrogel significantly enhanced vascular regeneration and reduced the inflammation in the in vivo wound repairing experiment. As a result, the CBPCa/PDA/DFO hydrogel may provide a promising therapeutic platform for diabetic trauma repairing.

Lack of glycemic control in type two diabetes mellitus patients is associated with reduced serum epidermal growth factor level and increased insulin resistance

The prevalence of type 2 diabetes mellitus (T2DM) is steadily increasing worldwide in an alarming fashion. Importantly, poor glycemic control is associated with development of various health sequalae's due to glucolipotoxicity, oxidative stress and increased inflammatory cytokines. The aim of the present study was to examine the effect of glycemic control on the relative abundance of inflammatory markers in patients with controlled and uncontrolled T2DM, and to test their association with the glycemic status in diabetic patients in Jordan. An observational cross-sectional study design was used. Patients with T2DM with controlled diabetes [glycated hemoglobin (HbA1c) ≤7.0%, n=110] and age-, sex- and body mass index (BMI)-matched uncontrolled diabetic patients (HbA1c >7.0%, n=105) were recruited. An antibody membrane array was used to examine the relative abundance of inflammatory cytokines and growth factors in the sera of the study subjects, followed by enzyme-linked immunosorbent assay (ELISA) to confirm the results. Fasting blood glucose, serum insulin, triglyceride and homeostatic model assessment for insulin resistance (HOMA-IR) score were significantly elevated in the uncontrolled T2DM group (P<0.05). Antibody membrane array showed that serum epidermal growth factor (EGF) is significantly decreased in the uncontrolled T2DM group, and this was confirmed by ELISA (158.77±111.7 vs. 95.9±82.7 pg/ml, P=0.002). The binary logistic model was used to predict the likelihood of being uncontrolled diabetic based on EGF levels. After controlling for age, sex and BMI, EGF was statistically associated with diabetes control, where lower EGF levels predicted uncontrolled diabetes. Additionally, Pearson's product-moment correlation showed a statistically significant negative correlation between EGF and HbA1c (r=-0.25, P<0.0001), and a positive correlation between HOMA-IR and HbA1c, (r=0.32, P<0.0001). The current data identify a novel link between serum EGF levels and the status of HbA1c indicative of diabetic control.

Epigenetic regulatory mechanism of macrophage polarization in diabetic wound healing (Review)

Diabetic wounds represent a significant complication of diabetes and present a substantial challenge to global public health. Macrophages are crucial effector cells that play a pivotal role in the pathogenesis of diabetic wounds, through their polarization into distinct functional phenotypes. The field of epigenetics has emerged as a rapidly advancing research area, as this phenomenon has the potential to markedly affect gene expression, cellular differentiation, tissue development and susceptibility to disease. Understanding epigenetic mechanisms is crucial to further exploring disease pathogenesis. A growing body of scientific evidence has highlighted the pivotal role of epigenetics in the regulation of macrophage phenotypes. Various epigenetic mechanisms, such as DNA methylation, histone modification and non‑coding RNAs, are involved in the modulation of macrophage phenotype differentiation in response to the various environmental stimuli present in diabetic wounds. The present review provided an overview of the various changes that take place in macrophage phenotypes and functions within diabetic wounds and discussed the emerging role of epigenetic modifications in terms of regulating macrophage plasticity in diabetic wounds. It is hoped that this synthesis of information will facilitate the elucidation of diabetic wound pathogenesis and the identification of potential therapeutic targets.

Orchestration of Macrophage Polarization Dynamics by Fibroblast-Secreted Exosomes during Skin Wound Healing

Macrophages undertake pivotal yet dichotomous functions during skin wound healing, mediating both early proinflammatory immune activation and late anti-inflammatory tissue remodeling processes. The timely phenotypic transition of macrophages from inflammatory M1 to proresolving M2 activation states is essential for efficient healing. However, the endogenous mechanisms calibrating macrophage polarization in accordance with the evolving tissue milieu remain undefined. In this study, we reveal an indispensable immunomodulatory role for fibroblast-secreted exosomes in directing macrophage activation dynamics. Fibroblast-derived exosomes permitted spatiotemporal coordination of macrophage phenotypes independent of direct intercellular contact. Exosomes enhanced macrophage sensitivity to both M1 and M2 polarizing stimuli, yet they also accelerated timely switching from M1 to M2 phenotypes. Exosome inhibition dysregulated macrophage responses, resulting in aberrant inflammation and impaired healing, whereas provision of exogenous fibroblast-derived exosomes corrected defects. Topical application of fibroblast-derived exosomes onto chronic diabetic wounds normalized dysregulated macrophage activation to resolve inflammation and restore productive healing. Our findings elucidate fibroblast-secreted exosomes as remote programmers of macrophage polarization that calibrate immunological transitions essential for tissue repair. Harnessing exosomes represents a previously unreported approach to steer productive macrophage activation states with immense therapeutic potential for promoting healing in chronic inflammatory disorders.

MCC950 promotes diabetic wound healing through modulating macrophage polarization in an MDSC-dependent manner

Diabetic foot ulcers (DFUs) are serious skin injuries whereby the wound healing process is frequently stalled in the inflammatory phase. Currently, there is a lack of effective therapeutic strategies. MCC950, a highly selective nod-like receptor family pyrin domain containing 3 (NLRP3) inhibitor, has been reported to show strong anti-inflammation effects in many diseases. In this study, we unveiled the role of MCC950 in DFU mice model and its underlying molecular mechanisms. MCC950 could significantly accelerate diabetic wound healing, as shown by shortened healing time and better healing quality. Moreover, increased M2 phenotype macrophages and decreased pro-inflammatory genes were observed in MCC950-treated DFU mice. Additionally, myeloid-derived suppressor cells (MDSCs) were significantly increased in blood, spleen and wound tissues at different time courses. Specifically, MCC950 could recruit more MDSCs in an early phase in DFU mice, exerting an anti-inflammation effect. We identified the cell crosstalk between macrophages and MDSCs with MCC950 treatment process. Depleting MDSCs in vivo could eliminate the therapeutic effect of MCC950 on diabetic wound healing through inhibiting M2 macrophage polarization. Besides, MDSCs isolated from the wounds of MCC950 or saline treated mice were cocultured with bone marrow derived macrophage (BMDM) in a transwell system. Results confirmed that MDSCs sorted from MCC950 treated mice caused a significant increased percentage of M2 macrophages. Collectively, our findings suggest that the administration of MCC950 has the potential to accelerate diabetic wound healing by promoting M2 macrophage polarization in an MDSC-dependent manner. This study provides valuable insights into the utilization of pharmacological agents for DFU treatment.

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.

Stiffness and surface topology of silicone implants competitively mediate inflammatory responses of macrophages and foreign body response

Adverse inflammatory responses, dominated by macrophages, that are induced by physical cues of silicone implants can heavily damage the life quality of patients via causing fibrosis and device failure. As stiffness and surface topology affect macrophages at the same time, the competition or partnership among physical cues against the regulation of macrophages is still ambiguous. Herein, a series of PDMS implants with different stiffness at ∼ MPa and surface topology at tens of micrometers were fabricated to investigate the relationship, the regulation rule, and the underlying mechanism of the two physical cues against the inflammatory responses of M1 macrophages. There is a competitive rule: surface topology could suppress the inflammatory responses of M1 macrophages in the soft group but did not have the same effect in the stiff group. Without surface topology, lower stiffness unexpectedly evoked stronger inflammatory responses of M1 macrophages. Implanting experiments also proved that the competitive state against mediating in vivo immune responses and the unexpected inflammatory responses. The reason is that stiffness could strongly up-regulate focal adhesion and activate the MAPK/NF-κB signaling axis to evoke inflammatory responses, which could shield the effect of surface topology. Therefore, for patient healthcare, it is crucial to prioritize stiffness while not surface topology at MPa levels to minimize adverse reactions.

The Immune-Centric Revolution Translated into Clinical Application: Peripheral Blood Mononuclear Cell (PBMNC) Therapy in Diabetic Patients with No-Option Critical Limb-Threatening Ischemia (NO-CLTI)-Rationale and Meta-Analysis of Observational Studies

Chronic limb-threatening ischemia (CLTI), the most advanced form of peripheral arterial disease (PAD), is the comorbidity primarily responsible for major lower-limb amputations, particularly for diabetic patients. Autologous cell therapy has been the focus of efforts over the past 20 years to create non-interventional therapeutic options for no-option CLTI to improve limb perfusion and wound healing. Among the different available techniques, peripheral blood mononuclear cells (PBMNC) appear to be the most promising autologous cell therapy due to physio-pathological considerations and clinical evidence, which will be discussed in this review. A meta-analysis of six clinical studies, including 256 diabetic patients treated with naive, fresh PBMNC produced via a selective filtration point-of-care device, was conducted. PBMNC was associated with a mean yearly amputation rate of 15.7%, a mean healing rate of 62%, and a time to healing of 208.6 ± 136.5 days. Moreover, an increase in TcPO2 and a reduction in pain were observed. All-cause mortality, with a mean rate of 22.2% and a yearly mortality rate of 18.8%, was reported. No serious adverse events were reported. Finally, some practical and financial considerations are provided, which point to the therapy's recommendation as the first line of treatment for this particular and crucial patient group.

Dental Pulp Stem Cell Lysate-Based Hydrogel Improves Diabetic Wound Healing via the Regulation of Anti-Inflammatory Macrophages and Keratinocytes

The prolonged existence of chronic wounds heightens the risk of patients experiencing chronic pain, necrosis, and amputation. Dental pulp stem cells (DPSCs) have garnered attention due to their potential immunomodulatory and tissue repair regenerative effects in the management of chronic wounds. However, stem-cell-based therapy faces challenges such as malignant differentiation, immune rejection, and long-term effectiveness. To overcome these challenges, we proposed a chronic wound therapy using a hydrogel derived from human-originated dental pulp stem cell lysate (DPSCL). Our data indicate that, with the degradation of the dental pulp stem cell lysate-based hydrogel (DPSCLH), the slowly released cell lysates recruit anti-inflammatory M2 macrophages and promote the proliferation, migration, and keratinization of HacaT cells. In addition, in vivo studies revealed that DPSCLH avoids immune rejection reactions and induces a long-term accumulation of endogenous M2 macrophages. In a mouse model of diabetic wounds, DPSCLH effectively modulates the inflammatory microenvironment around diabetic wounds, promotes the formation of the stratum corneum, and facilitates the healing of wounds, thus holding tremendous potential for the treatment of diabetic wounds.

Inflammation-Modulating Biomedical Interventions for Diabetic Wound Healing: An Overview of Preclinical and Clinical Studies

A diabetic wound exemplifies the challenge of chronic, nonhealing wounds. Elevated blood sugar levels in diabetes profoundly disrupt macrophage function, impairing crucial activities such as phagocytosis, immune response, cell migration, and blood vessel formation, all essential for effective wound healing. Moreover, the persistent presence of pro-inflammatory cytokines and reactive oxygen species, coupled with a decrease in anti-inflammatory factors, exacerbates the delay in wound healing associated with diabetes. This review emphasizes the dysfunctional inflammatory responses underlying diabetic wounds and explores preclinical studies of inflammation-modulating bioactives and biomaterials that show promise in expediting diabetic wound healing. Additionally, this review provides an overview of selected clinical studies employing biomaterials and bioactive molecules, shedding light on the gap between extensive preclinical research and limited clinical studies in this field.

Topical Reconstituted High-Density Lipoproteins Elicit Anti-Inflammatory Effects in Diabetic Wounds

Objective: Reconstituted high-density lipoproteins (rHDL) improve wound healing in diabetes. We aimed to determine if rHDL elicit anti-inflammatory effects in diabetic wounds, as a mechanism to explain their wound healing benefits. Approach: Diabetes was induced using streptozotocin in C57Bl6/J mice. Two full-thickness wounds were placed on the subflanks of diabetic and nondiabetic (ND) mice. Phosphate-buffered saline (PBS) or rHDL (50 µg/wound/day) were applied topically. Wound closure was assessed daily. Inflammatory gene transcripts were measured by qPCR and proteins by Western blotting and enzyme-linked immunosorbent assay in wounds collected at baseline, 24 h, and 3 days postwounding. Wound macrophages were assessed by flow cytometry 7 days postwounding. The fate of fluorescent 3,3-dioctadecyloxacarbocyanine, perchlorate (DiO)-labeled rHDL was tracked by flow cytometry, fluorescent imaging, and microscopy. Results: In diabetic mice, rHDL increased wound closure rates at days 6 (+288%, p < 0.01) and 7 (+639%, p < 0.0001) postwounding, compared with PBS controls. After 3 days, rHDL-treated diabetic wounds had lower Rela (-65%) and C-C motif chemokine ligand 2 (Ccl2) (-59%) mRNA levels and CCL2 protein (29%) than PBS controls, p < 0.05 for all. Wound macrophage content was higher in diabetic than ND wounds, but rHDL did not change macrophage content or polarity. DiO-rHDL were taken up by key wound cells including fibroblasts, macrophages, keratinocytes and endothelial cells, and retained in wounds for at least 48 h. Innovation: rHDL exerts anti-inflammatory effects in diabetic wounds early postwounding, which may contribute to its wound healing properties. Conclusion: The anti-inflammatory properties of rHDL in diabetic wounds present topical rHDL as a novel treatment option for improving healing in patients with diabetic foot ulcers.

Mesoporous bioactive glass-enhanced MSC-derived exosomes promote bone regeneration and immunomodulation in vitro and in vivo

BACKGROUND

Exosomes produced by mesenchymal stem cells (MSCs) have vascular generative properties and are considered new effective candidates for the treatment of bone defects as alternatives to cell therapy. Improving the pro-regenerative function and efficacy of exosomes has been a popular research topic in the field of orthopaedics.

METHODS

We prepared mesoporous bioactive glass (mBG) microspheres via the template method. The ionic products of mBGs used to treat MSCs were extracted, and the effects of exosomes secreted by MSCs on osteoblast (OB) and macrophage (MP) behaviour and bone defect repair were observed in vivo (Micro-CT, H&E, Masson, and immunofluorescence staining for BMP2, COL1, VEGF, CD31, CD163, and iNOS).

RESULTS

The mBG spheres were successfully prepared, and the Exo-mBG were isolated and extracted. Compared with those in the blank and Exo-Con groups, the proliferation and osteogenic differentiation of OBs in the Exo-mBG group were significantly greater. For example, on Day 7, OPN gene expression in the Ctrl-Exo group was 3.97 and 2.83 times greater than that in the blank and Exo-mBG groups, respectively. In a cranial defect rat model, Exo-mBG promoted bone tissue healing and angiogenesis, increased M2 macrophage polarisation and inhibited M1 macrophage polarisation, as verified by micro-CT, H&E staining, Masson staining and immunofluorescence staining. These effects may be due to the combination of a higher silicon concentration and a higher calcium-to-phosphorus ratio in the mBG ionic products.

CONCLUSION

This study provides insights for the application of exosomes in cell-free therapy and a new scientific basis and technical approach for the utilisation of MSC-derived exosomes in bone defect repair.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

Our study demonstrated that exosomes produced by mBG-stimulated MSCs have excellent in vitro and in vivo bone-enabling and immunomodulatory functions and provides insights into the use of exosomes in clinical cell-free therapies.

The Core-Shell Microneedle with Probiotic Extracellular Vesicles for Infected Wound Healing and Microbial Homeostasis Restoration

Wound healing is a dynamic process involving the timely transition of organized phases. However, infected wounds often experience prolonged inflammation due to microbial overload. Thus, addressing the viable treatment needs across different healing stages is a critical challenge in wound management. Herein, a novel core-shell microneedle (CSMN) patch is designed for the sequential delivery of tannic acid-magnesium (TA-Mg) complexes and extracellular vesicles from Lactobacillus druckerii (LDEVs). Upon application to infected sites, CSMN@TA-Mg/LDEV releases TA-Mg first to counteract pathogenic overload and reduce reactive oxygen species (ROS), aiding the transition to proliferative phase. Subsequently, the sustained release of LDEVs enhances the activities of keratinocytes and fibroblasts, promotes vascularization, and modulates the collagen deposition. Notably, dynamic track of microbial composition demonstrates that CSMN@TA-Mg/LDEV can both inhibit the aggressive pathogen and increase the microbial diversity at wound sites. Functional analysis further highlights the potential of CSMN@TA-Mg/LDEV in facilitating wound healing and skin barrier restoration. Moreover, it is confirmed that CSMN@TA-Mg/LDEV can accelerate wound closure and improve post-recovery skin quality in the murine infected wound. Conclusively, this innovative CSMN patch offers a rapid and high-quality alternative treatment for infected wounds and emphasizes the significance of microbial homeostasis.

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.

Recent advances in sodium alginate-based dressings for targeted drug delivery in the context of diabetic wound healing

Diabetic wounds pose a significant challenge in healthcare due to impaired healing and increased risk of complications. In recent years, various drug delivery systems with stimuli-responsive features have been developed to address these issues. These systems enable precise dosage control and tailored drug release, promoting comprehensive tissue repair and regeneration. This review explores targeted therapeutic agents, such as carboxymethyl chitosan-alginate hydrogel formulations, nanofiber mats, and core-shell nanostructures, for diabetic wound healing. Additionally, the integration of nanotechnology and multifunctional biomimetic scaffolds shows promise in enhancing wound healing outcomes. Future research should focus on optimizing the design, materials, and printing parameters of 3D-bio-printed wound dressings, as well as exploring combined strategies involving the simultaneous release of antibiotics and nitric oxide for improved wound healing.

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.

The Angiogenic Repertoire of Stem Cell Extracellular Vesicles: Demystifying the Molecular Underpinnings for Wound Healing Applications

Stem cells-derived extracellular vesicles (SC-EVs) have emerged as promising therapeutic agents for wound repair, recapitulating the biological effects of parent cells while mitigating immunogenic and tumorigenic risks. These EVs orchestrate wound healing processes, notably through modulating angiogenesis-a critical event in tissue revascularization and regeneration. This study provides a comprehensive overview of the multifaceted mechanisms underpinning the pro-angiogenic capacity of EVs from various stem cell sources within the wound microenvironment. By elucidating the molecular intricacies governing their angiogenic prowess, we aim to unravel the mechanistic repertoire underlying their remarkable potential to accelerate wound healing. Additionally, methods to enhance the angiogenic effects of SC-EVs, current limitations, and future perspectives are highlighted, emphasizing the significant potential of this rapidly advancing field in revolutionizing wound healing strategies.

Nrf2 Activation in Keratinocytes: A Central Role in Diabetes-Associated Wound Healing

Wound healing is a complex biological process crucial for tissue repair, wherein keratinocytes play a pivotal role in initiating, sustaining and completing the cascade. Various local and systemic factors, such as lifestyle, age metabolic disorders and vascular insufficiency, can influence this process, and in the context of diabetic wounds, disrupted biological mechanisms, including inflammation, tissue hypoxia, decrease in collagen production along with increased oxidative stress and keratinocyte dysfunction, contribute to delayed healing. During re-epithelialisation, keratinocytes undergo rapid multiplication and migration, forming a dense hyperproliferative epithelial layer that restores the epidermal barrier. Nuclear factor-erythroid 2-related factor (Nrf2), a vital transcription factor, emerges as a central regulator in managing antioxidant proteins and detoxifying enzymes, serving as a guardian against elevated reactive oxygen species (ROS) levels during stress. Nrf2 also orchestrates angiogenesis and anti-inflammatory responses crucial for wound repair. Studies demonstrate that under high-glucose conditions, Nrf2 activation promotes wound healing by enhancing cell proliferation and migration while reducing apoptosis. Nrf2 activators stimulate endogenous antioxidant production, thereby mitigating oxidative stress. Furthermore, Nrf2 upregulation is associated with decreased expression of cytokines such as TNF-α and IL- 6. Recent research underscores the potential of bioactive molecules, including dietary polyphenols, traditional medicinal compounds and pharmacological agents, in activating Nrf2 and preventing diseases such as diabetes due to their robust antioxidative properties. This review aims to investigate the activation of Nrf2 by these bioactive molecules in cultured keratinocytes and animal models, elucidating the key molecular regulatory mechanisms involved in alleviating oxidative stress and facilitating the diabetic wound healing process. Understanding these complex pathways may offer insights into novel therapeutic strategies for enhanced wound healing in diabetes-associated complications.

l-Arginine-Loaded Oxidized Isabgol/Chitosan-Based Biomimetic Composite Scaffold Accelerates Collagen Synthesis, Vascularization, and Re-epithelialization during Wound Healing in Diabetic Rats

Impaired wound healing in diabetic wounds is common due to infection, inflammation, less collagen synthesis, and vascularization. Diabetic wound healing in patients is still a challenge and needs an ideal wound dressing to treat and manage diabetic wounds. Herein, an efficacious wound dressing biomaterial was fabricated by cross-linking oxidized isabgol (Oisab) and chitosan (Cs) via trisodium trimetaphosphate and Schiff base bonds. l-Arginine (l-Arg) was incorporated as a bioactive substance in the Oisab + Cs scaffold to promote cell adhesion, cell proliferation, collagen synthesis, and vascularization. The fabricated scaffolds showed microporous networks in the scanning electron microscopy analysis. The scaffold also possessed excellent hemocompatibility. In vitro studies using fibroblasts (L929 and human dermal fibroblast cells) confirmed the cytocompatibility of these scaffolds. The results of the in vivo chicken chorioallantoic membrane assay confirmed the proangiogenic activity of the Oisab + Cs + l-Arg scaffolds. The wound-healing potential of these scaffolds was studied in streptozotocin-induced diabetic rats. This in vivo study showed that the period of epithelialization in the Oisab + Cs + l-Arg scaffold-treated wounds was 21.67 ± 1.6 days, which was significantly faster than the control (30.33 ± 2.5 days). Histological and immunohistochemical studies showed that the Oisab + Cs + l-Arg scaffolds significantly accelerated the rate of wound contraction by reducing inflammation, improving collagen synthesis, and promoting neovascularization. These findings suggest that the Oisab + Cs + l-Arg scaffolds could be beneficial in treating diabetic wounds in clinical applications.

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.

Anthocyanidin-Loaded Superabsorbent Self-Pumping Dressings for Macrophage Immunomodulation and Diabetic Wound Healing

Management of diabetic chronic wound exudate is a serious challenge in healthcare worldwide since it is related to the speed of diabetic wound healing. However, current foam dressings not only absorb fluid to generate swelling and compress the wound to hinder wound healing but also are very thick and less comfortable to use. Herein, a superabsorbent self-pumping ultrathin dressing is reported to accelerate diabetic wound healing by achieving superior exudate absorption and management in an ultrathin state. The self-pumping dressing is composed of a drainage layer loaded with anthocyanidin and a thermoplastic polyurethane absorbent layer embedded with superabsorbent particles. The dressing realizes the self-pumping process of unidirectional exudate draining to the absorption layer through the drainage layer without significant dressing swelling to compress the diabetic wound. The dressing is experimentally proven to unidirectionally drain excessive exudate with inflammatory factors and modulate the conversion of macrophages from M1 to M2 in diabetic wounds, thereby promoting the healing of diabetic skin ulcers faster than commercial foam dressings. Therefore, the dressing provides a new idea and novel method for accelerating diabetic skin ulcer healing.

Adipose stem cell-derived exosomes in the treatment of wound healing in preclinical animal models: a meta-analysis

Background

Wound healing has always been a serious issue for doctors and primary health care systems. In addition, adipose stem cell-derived exosomes have been proven to play a positive and effective role in tissue repair and regeneration. A systematic review of these preclinical studies was performed to assess the efficacy of adipose stem cell-derived exosomes (ADSC-Exos) in treating wounds. This article aimed to study the effectiveness of ADSC-Exos for the treatment of animal skin wounds and includes a meta-analysis of exosomes from general wounds and diabetic ulcer wounds in in vitro models of animals to provide a theoretical basis for clinical translation.

Methods

A total of 19 studies with 356 animals were identified by searching the PubMed, Cochrane, MEDLINE Complete, Web of Science, CNKI and Wanfang databases from inception to 15 November 2022. No language or time restrictions were applied. Stata17 was used for all the data analyses.

Results

The meta-analysis showed that ADSC-Exo therapy significantly improved the wound healing rate in the control group, except in the diabetes group on day 7. Day 7 of general wounds [standard mean difference (SMD) 2.87, 95% confidence interval (CI) 1.91-3.83)] and day 14 (SMD 2.89, 95%CI 1.47-4.30). Day 14 (SMD 3.43, 95%CI 1.28-5.58) of diabetic wounds. Other outcomes, such as blood vessel density, collagen deposition and wound re-epithelization, improved with the administration of ADSC-Exos.

Conclusions

A meta-analysis showed that ADSC-Exo therapy applied to general and diabetic wounds can promote neovascularization, improve epithelization and collagen fiber deposition, promote healing, and reduce scar formation. ADSC-Exos have broad potential in preclinical research and clinical fields.

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.

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.

A bioenergetically-active ploy (glycerol sebacate)-based multiblock hydrogel improved diabetic wound healing through revitalizing mitochondrial metabolism

Diabetic wounds impose significant burdens on patients' quality of life and healthcare resources due to impaired healing potential. Factors like hyperglycemia, oxidative stress, impaired angiogenesis and excessive inflammation contribute to the delayed healing trajectory. Mounting evidence indicates a close association between impaired mitochondrial function and diabetic complications, including chronic wounds. Mitochondria are critical for providing energy essential to wound healing processes. However, mitochondrial dysfunction exacerbates other pathological factors, creating detrimental cycles that hinder healing. This study conducted correlation analysis using clinical specimens, revealing a positive correlation between mitochondrial dysfunction and oxidative stress, inflammatory response and impaired angiogenesis in diabetic wounds. Restoring mitochondrial function becomes imperative for developing targeted therapies. Herein, we synthesized a biodegradable poly (glycerol sebacate)-based multiblock hydrogel, named poly (glycerol sebacate)-co-poly (ethylene glycol)-co-poly (propylene glycol) (PEPGS), which can be degraded in vivo to release glycerol, a crucial component in cellular metabolism, including mitochondrial respiration. We demonstrate the potential of PEPGS-based hydrogels to improve outcomes in diabetic wound healing by revitalizing mitochondrial metabolism. Furthermore, we investigate the underlying mechanism through proteomics analysis, unravelling the regulation of ATP and nicotinamide adenine dinucleotide metabolic processes, biosynthetic process and generation during mitochondrial metabolism. These findings highlight the therapeutic potential of PEPGS-based hydrogels as advanced wound dressings for diabetic wound healing.

Turning sublimed sulfur and bFGF into a nanocomposite to accelerate wound healing via co-activate FGFR and Hippo signaling pathway

Clinical treatment of diabetic refractory ulcers is impeded by chronic inflammation and cell dysfunction associated with wound healing. The significant clinical application of bFGF in wound healing is limited by its instability in vivo. Sulfur has been applied for the treatment of skin diseases in the clinic for antibiosis. We previously found that sulfur incorporation improves the ability of selenium nanoparticles to accelerate wound healing, yet the toxicity of selenium still poses a risk for its clinical application. To obtain materials with high pro-regeneration activity and low toxicity, we explored the mechanism by which selenium-sulfur nanoparticles aid in wound healing via RNA-Seq and designed a nanoparticle called Nano-S@bFGF, which was constructed from sulfur and bFGF. As expected, Nano-S@bFGF not only regenerated zebrafish tail fins and promoted skin wound healing but also promoted skin repair in diabetic mice with a profitable safety profile. Mechanistically, Nano-S@bFGF successfully coactivated the FGFR and Hippo signalling pathways to regulate wound healing. Briefly, the Nano-S@bFGF reported here provides an efficient and feasible method for the synthesis of bioactive nanosulfur and bFGF. In the long term, our results reinvigorated efforts to discover more peculiar unique biofunctions of sulfur and bFGF in a great variety of human diseases.

Verapamil and tangeretin enhances the M1 macrophages to M2 type in lipopolysaccharide-treated mice and inhibits the P-glycoprotein expression by downregulating STAT1/STAT3 and upregulating SOCS3

LPS induced sepsis is a complex process involving various immune cells and signaling molecules. Dysregulation of macrophage polarization and ROS production contributed to the pathogenesis of sepsis. PGP is a transmembrane transporter responsible for the efflux of a number of drugs and also expressed in murine macrophages. Natural products have been shown to decrease inflammation and expression of efflux transporters. However, no treatment is currently available to treat LPS induced sepsis. Verapamil and Tangeretin also reported to attenuate lipopolysaccharide-induced inflammation. However, the effects of verapamil or tangeretin on lipopolysaccharide (LPS)-induced sepsis and its detailed anti-inflammatory mechanism have not been reported. Here, we have determined that verapamil and tangeretin protects against LPS-induced sepsis by suppressing M1 macrophages populations and also through the inhibition of P-glycoprotein expression via downregulating STAT1/STAT3 and upregulating SOCS3 expression in macrophages. An hour before LPS (10 mg/kg) was administered; mice were given intraperitoneal injections of either verapamil (5 mg/kg) or tangeretin (5 mg/kg). The peritoneal macrophages from different experimental groups of mice were isolated. Hepatic, pulmonary and splenic morphometric analyses revealed that verapamil and tangeretin decreased the infiltration of neutrophils into the tissues. Verapamil and tangeritin also enhanced the activity of SOD, CAT, GRX and GSH level in all the tissues tested. verapamil or tangeretin pre-treated mice shifted M1 macrophages to M2 type possibly through the inhibition of P-glycoprotein expression via downregulating STAT1/STAT3 and upregulating SOCS3 expression. Hence, both these drugs have shown protective effects in sepsis via suppressing iNOS, COX-2, oxidative stress and NF-κB signaling in macrophages. Therefore, in our study we can summarize that mice were treated with either Vera or Tan before LPS administration cause an elevated IL-10 by the macrophages which enhances the SOCS3 expression, and thereby able to limits STAT1/STAT3 inter-conversion in the macrophages. As a result, NF-κB activity is also getting down regulated and ultimately mitigating the adverse effect of inflammation caused by LPS in resident macrophages. Whether verapamil or tangeretin offers such protection possibly through the inhibition of P-glycoprotein expression in macrophages needs clarification with the bio availability of these drugs under PGP inhibited conditions is a limitation of this study.

Hydrogen sulfide regulates macrophage polarization and necroptosis to accelerate diabetic skin wound healing

Hydrogen sulfide (H2S), recognized as the third gasotransmitter, plays a pivotal role in the pathophysiological processes of various diseases. Cystathionine γ-lyase (CSE) is the main enzyme for H2S production in the skin. However, effects and mechanisms of H2S in diabetic skin wound healing remain unclear. Our findings revealed a decrease in plasma H2S content in diabetic patients with skin wounds. CSE knockout (KO) diabetic mice resulted in delayed wound healing, reduced blood perfusion, and CD31 expression around the wounds. It also led to increased infiltration of inflammatory cells and M1-type macrophages, decreased collagen levels, α-smooth muscle actin (α-SMA), and proliferating cell nuclear antigen (PCNA) expression. Additionally, there were enhanced expressions of necroptosis related proteins, including receptor interacting protein kinase 1 (RIPK1), RIPK3 and mixed lineage kinase domain like protein (MLKL). In comparison, sodium hydrosulfide (NaHS), H2S donor, accelerated skin wound healing in leptin receptor deficiency (db/db) mice. This acceleration was accompanied by increased blood perfusion and CD31 expression, reduced infiltration of inflammatory cells and M1-type macrophages, elevated collagen levels, α-SMA, and PCNA expressions, and decreased necroptosis-related protein expressions together with nuclear factor-κB (NF-κB) p65 phosphorylation. In conclusion, H2S regulates macrophage polarization and necroptosis, contributing to the acceleration of diabetic skin wound healing. These findings offer a novel strategy for the treatment of diabetic skin wounds.

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.

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.

A Novel Self-Pumping Janus Dressing for Promoting Wound Immunomodulation and Diabetic Wound Healing

Self-pumping dressings become one of the optimal solutions for the controlled management of chronic diabetic wound exudate and wound healing. However, present self-pumping dressings are not only prone to breakage of the loose hydrophobic layer but also have cumbersome and complicated preparation steps, which hinder the application of self-pumping dressings in diabetic wound treatment. Herein, a novel self-pumping structure of superabsorbent Janus dressing is designed to improve the strength of the hydrophobic layer and promote diabetic wound healing. The Janus dressing consists of a hydrophobic layer with a drainage agent (drainage layer) and a fluffy 3D nanofiber cotton (absorbent layer). Regardless of the thickness of the drainage layer, the drainage agent in the drainage layer provides the fluid to penetrate the drainage layer to the absorbent layer for unidirectional fluid draining. In design proof, the superabsorbent Janus dressing provides unidirectional drainage of inflammatory exudate and regulation of macrophage polarization, resulting in faster diabetic wound healing than single-layer dressings. Thus, the Janus dressing demonstrates important clinical implications to offer a novel design and preparation strategy for accelerating diabetic wound healing.

Epigenetic modification: A novel insight into diabetic wound healing

Wound healing is an intricate and fine regulatory process. In diabetic patients, advanced glycation end products (AGEs), excessive reactive oxygen species (ROS), biofilm formation, persistent inflammation, and angiogenesis regression contribute to delayed wound healing. Epigenetics, the fast-moving science in the 21st century, has been up to date and associated with diabetic wound repair. In this review, we go over the functions of epigenetics in diabetic wound repair in retrospect, covering transcriptional and posttranscriptional regulation. Among these, we found that histone modification is widely involved in inflammation and angiogenesis by affecting macrophages and endothelial cells. DNA methylation is involved in factors regulation in wound repair but also affects the differentiation phenotype of cells in hyperglycemia. In addition, noncodingRNA regulation and RNA modification in diabetic wound repair were also generalized. The future prospects for epigenetic applications are discussed in the end. In conclusion, the study suggests that epigenetics is an integral regulatory mechanism in diabetic wound healing.