Single cell transcriptomic landscape of diabetic foot ulcers

Regulation of osteoimmune microenvironment via functional dynamic hydrogel for diabetic bone regeneration

Bone regeneration and repair face formidable challenges under diabetic conditions, primarily due to the disruption of macrophage polarization induced by diabetes and the inflammatory imbalance within the bone microenvironment. We have developed a novel dynamic hydrogel system (AG-CD@LINA), constructed through the coordination crosslinking of thiolated gelatin (SH-Gelatin) and gold ions (Au3+), followed by grafting with cyclodextrin to load the ligand linagliptin. This hydrogel effectively inhibits the formation of M1 macrophages and the expression of pro-inflammatory cytokines by gradually releasing linagliptin. Simultaneously, it promotes the formation of M2 macrophages and the expression of anti-inflammatory cytokines, thus improving the inflammatory microenvironment of diabetic bone defects. Consequently, it facilitates the migration of mesenchymal stem cells and angiogenic cells, augments osteogenic activity, and promotes vascularization, collectively accelerating the regeneration of diabetic bone tissue. Mechanistically, polarization occurs through the TLR3-NF-κB signaling pathway. In vivo experiments demonstrate that the in-situ injection of the hydrogel enhances the regeneration of bone tissue and the restoration of bone structure in diabetic bone defects, effectively modulating local inflammation and promoting vascular formation. This study suggests that functionalized dynamic hydrogels can improve the inflammatory microenvironment by regulating in situ macrophage polarization, thereby facilitating the reconstruction of bone microstructure. This approach represents a promising novel therapeutic strategy for diabetic bone defects.

Shark skin and mussel-inspired polyurethane hydrogel sponge for wounds with infection and exudate

Inspired by the antifouling properties of shark skin and the bioadhesion of mussels, our study presents a three-layer biomimetic wound dressing with hierarchical wettability and rapid exudate drainage capabilities. The shark skin-inspired hydrophobic modified polyurethane (PU) sponge provides antifouling properties and serves as a bacterial barrier. The mussel-inspired dopamine-functionalized carboxymethyl chitosan hydrogel (CMCS-DOP) absorbs exudates and forms an in situ hydrogel, effectively capturing and eliminating bacteria. The porous sponge layer in direct contact with the wound facilitates rapid exudate drainage, preventing excessive wound hydration. This hierarchical structure coordinates exudate transport and bacterial removal. The fabricated PCD hydrogel sponge dressing (PCD dressing) exhibits a wettability transition (contact angle: 3°-35°-101°) and a water vapor transmission rate of 1021-797-691 g/m2. It demonstrates potent bactericidal effects against Staphylococcus aureus and Escherichia coli, with survival rates of only 13 % and 14 %, respectively, and bacterial-blocking efficiencies of 89 % and 94 %. In a chronic bacterial infection wound model, the PCD dressing outperforms conventional clinical dressings, increasing the wound healing rate by 25.8 %, reducing inflammation, and enhancing angiogenesis and collagen deposition. Notably, the PCD mitigates oxidative stress at the wound site by regulating the polarization of anti-inflammatory macrophages. This exudate-draining and responsive dressing offers a promising strategy for promoting the healing of wounds with high exudate levels.

Nano co-inducer of immunogenic cell death and ferroptosis for anti-tumor immunotherapy

Due to population aging and lifestyle changes, the global tumor burden has increased, making tumor disease a significant challenge in public health. Recently, immunotherapy emerged as an effective approach for tumor treatment by activating and enhancing the body's immune system to precisely identify and attack tumor cells. However, its efficacy was limited by the "cold" immunosuppressive tumor microenvironment (ITME) and the tissue repair capabilities of tumors. To address this issue, we developed a dual-target ferroptosis immune-inducer, FTB@CC, which releases photosensitizer (PS), calcium (Ca2+), and Fe2+ under weakly acidic conditions. Upon near-infrared (NIR) laser irradiation, PSs induced endoplasmic reticulum (ER) stress, producing large amounts of reactive oxygen species (ROS) and releasing significant quantities of damage-associated molecular patterns (DAMPs), which mediated immunogenic cell death (ICD). Simultaneously, Ca2+ overload activates the inflammasome and amplifies cellular cytotoxicity for DAMPs release, eventually activating the ICD pathway. The supplementation of Fe2+ increased iron storage within tumor cells and downregulated the expression of glutathione peroxidase 4 (GPX4), leading to the accumulation of lipid peroxides (LPO) and ultimately resulting in ferroptosis. This multi-level interaction strategy restructured the ITME and induced ICD, overcoming the limitations of single-agent therapies, and significantly enhancing the efficacy of anti-PD-L1 antibody (α-PD-L1) in suppressing tumor cell immune evasion. As a result, it promoted the infiltration of immune cells and inhibited both distal and proximal tumors. This nano-integrated ICD-ferroptosis co-inducer offers an intelligent strategy for effectively overcoming ITME, thereby providing a promising avenue for advanced immunotherapeutic interventions.

Progress of microneedle targeted modulation technology in the reconstruction of immune microenvironment in diabetic wounds

Wound healing in diabetic patients is mainly hindered by a combination of long-term glycosylation, persistent inflammatory response, and immunosuppressive state. The interaction of these factors not only results in considerable prolongation of the wound healing process but also elevates the likelihood of recurrent ulcer development, profoundly affecting patients' quality of life. Traditional treatments, including surgical debridement, anti-infection, dressing application, vascular intervention, and glycaemic control, can only relieve some symptoms. However, they are often ineffective in addressing the underlying cause of impaired wound healing. It is of concern that the importance of the immune microenvironment in diabetic wound healing has not yet been fully appreciated and investigated, and the homeostasis of the immune microenvironment is crucial for promoting cell proliferation, angiogenesis, and tissue repair. However, this microenvironment is often dysregulated in the diabetic state. This paper reviews the key factors leading to dysregulation of the immune microenvironment, including immune cell dysfunction, abnormal cytokine expression, and disruption of key signalling pathways, and introduces an innovative silicone-based microneedle drug delivery method, which takes advantage of microneedle's precise targeting and highly efficient drug loading capacity to deliver drugs with immunomodulatory functions directly to the wound in a sustained manner, activate the corresponding signalling pathways, promote the polarization of M1 macrophages into the M2 phenotype, and stimulate neovascularization, providing a low inflammatory and pro-angiogenic immune microenvironment for diabetic wound healing, which provides a new therapeutic idea and means for diabetic wound healing.

Potential Role of CD99 Signaling Pathway in Schwann Cell Dysfunction in Diabetic Foot Ulcers Based on Single-Cell Transcriptome Analysis

Background: Schwann cell (SC) dysfunction contributes to the delayed healing of diabetic foot ulcers (DFUs). However, the underlying molecular mechanism regarding the unregulated SC function is poorly understood. Thus, we examined the single-cell transcriptome data from different DFU states focusing on SC characteristics. Methods: The single-cell RNA sequencing (scRNA-seq) data of DFU was obtained from the Gene Expression Omnibus (GEO) database, covering foot skin samples from nondiabetic patients, diabetic patients without DFU, DFU healers, and DFU nonhealers. After scRNA-seq data processing, downscaling, and cell cluster identification, cell communication analysis was performed by the CellChat package. Furthermore, we subclustered SC populations and ran the trajectory inference and pseudotime analysis to investigate the dynamic changes in SC. Finally, the significant pathways were validated with a db/db mouse wound model. Results: scRNA-seq analysis revealed different SC percentages and gene markers across the DFU groups. We identified that the CD99 signaling pathway was upregulated in the DFU nonhealer group. In the db/db mouse wound model, we observed that CD99 was highly expressed in the demyelinated area of the peripheral nerve fibers. Conclusion: Our study elucidated that the CD99 pathway activation may play a crucial role in SC dysfunction of DFU, providing insights into the peripheral glia regulation mechanism and potential therapeutic target of DFU.

Dysfunctional crosstalk between macrophages and fibroblasts under LPS-infected and hyperglycemic environment in diabetic wounds

Diabetic wounds, especially diabetic foot ulcers, present a major clinical challenge due to delayed healing and prolonged inflammation. Macrophage-fibroblast interactions are essential for wound repair, yet this crosstalk is disrupted in diabetic wounds due to hyperglycemia and bacterial infection. This study investigates the dysfunctional communication between macrophages and fibroblasts, focusing on autocrine, paracrine, and juxtacrine signaling in simulated diabetic environments. Using monoculture and co-culture models of THP-1-derived macrophages and primary human dermal fibroblasts, we simulated conditions of normal glucose, LPS-induced infection, high glucose (with AGEs), and combined high glucose (with AGEs) and LPS. Macrophages in hyperglycemic and LPS-infected environments exhibited a pro-inflammatory M1 phenotype with elevated expression of CD80, and STAT1 and increased production of IL-1β, TNF-α, and MMP9. Fibroblast migration was significantly impaired under high glucose conditions, particularly in paracrine model. Secretome profiling showed heightened pro-inflammatory cytokines and proteases, with reduced anti-inflammatory markers (IL-10 and VEGF-A) under hyperglycemic conditions. Paracrine signaling exacerbated the inflammatory response, while juxtacrine signaling showed more moderate effects, conducive to healing. These findings highlight the pathological macrophage-fibroblast crosstalk in diabetic wounds, particularly under hyperglycemic and LPS-infected conditions, offering insights for potential immunomodulatory therapies aimed at restoring effective signaling and improving wound healing outcomes.

The Role of Omics Techniques in Diabetic Wound Healing: Recent Insights into the Application of Single-Cell RNA Sequencing, Bulk RNA Sequencing, Spatial Transcriptomics, and Proteomics

Diabetic foot ulcers (DFUs) are a devastating complication of diabetes mellitus (DM) that affect millions of people worldwide every year. They have a long-term impact on patients' quality of life and pose a significant challenge for both patients and clinicians, alongside negative economic implications on affected individuals. The current therapeutic approaches are costly and, in many cases, ineffective, highlighting the urgent need to develop novel, affordable, more efficient, and personalized treatments. Recent advances in high-throughput omics technologies, including proteomics, bulk RNA sequencing (bulk RNA-seq), single-cell RNA sequencing (scRNA-seq), and spatial transcriptomics in both preclinical animal and human clinical studies, have enhanced our understanding of the molecular function and mechanisms of DFUs, thereby offering potential for targeted therapies. Additionally, these technologies provide valuable insights behind the mechanism of action of novel wound dressings and treatments. In this review, we outline the latest application of omics technologies in DFU preclinical animal and human clinical research on diabetic wound healing, and spotlight recent findings.A graphical abstract is available with this article.

Dysregulated mast cell activation induced by diabetic milieu exacerbates the progression of diabetic peripheral neuropathy in mice

Diabetic peripheral neuropathy (DPN), a common disorder in diabetes, is associated with severe microenvironment imbalance due to immunometabolic stress. However, the underlying mechanistic drivers remain unclear. Here, we generate a single-cell atlas of human peripheral nerves and identify cell-specific transcriptional changes in DPN as well as aberrant amplification of mast cells. Using streptozotocin-induced mouse diabetes models, we further find that glucose uptake mediated by GLUT3 in high-glucose (HG) diabetic milieu upregulates ERK1/2 phosphorylation in mouse mast cells. Sustained HG stimulation also induces aberrant mTOR hyperactivity, resulting in endoplasmic reticulum stress and mitochondrial oxidative stress, thereby impairing mitochondrial functions of mast cells. Dysregulated mast cells then degranulate and release histamine, tryptase and inflammatory factors into neural microenvironment to cause neuropathy in diabetic mice. Lastly, mice with mast cell deficiency are protected from the immune imbalance in nerves and progression of neuropathy. Our findings thus implicate dysregulated activation of mast cells as a potential driver in the progression of DPN.

Diabetic foot in the context of rheumatic diseases: pathogenesis and treatment approaches

Diabetic foot is a frequent and debilitating complication of diabetes mellitus that significantly impairs quality of life and increases the risk of disability and amputation. This review examines the multifactorial pathogenesis of diabetic foot, focusing on its increased incidence and severity in patients with rheumatic diseases. The development of diabetic foot is driven by diabetic neuropathy, peripheral vascular disease, and infection. In patients with rheumatic diseases, chronic systemic inflammation and vascular dysfunction further accelerate tissue damage and impair wound healing. Long-term use of pharmacologic agents such as glucocorticoids and nonsteroidal anti-inflammatory drugs also contributes to metabolic imbalance, immune suppression, and vascular complications, increasing the risk of ulceration and infection. Rheumatic disease-related joint deformities and altered foot biomechanics add mechanical stress, exacerbating the condition. Effective management of diabetic foot in patients with rheumatic diseases requires a multidisciplinary approach. This includes early diagnosis, strict glycemic control, modulation of systemic inflammation, optimization of vascular health, and preventive foot care strategies. Addressing both metabolic and rheumatologic components is essential to reduce the risk of severe outcomes such as chronic infection and limb amputation. Understanding the interplay between diabetes and rheumatic diseases is crucial for improving clinical outcomes. Targeted, integrated interventions are key to preventing complications and enhancing the quality of life for affected patients.

Deciphering the Dysregulating IGF-1-SP1-CD248 Pathway in Fibroblast Functionality during Diabetic Wound Healing

Reduced fibroblast activity is a critical factor in the progression of diabetic ulcers. CD248, a transmembrane glycoprotein prominently expressed in activated fibroblasts, plays a pivotal role in wound healing. However, the role of CD248 in diabetic wound healing and the CD248 regulatory pathway remains largely unexplored. Our study shows that CD248 expression is significantly reduced in skin wounds from both patients and mice with diabetes. Single-cell transcriptome data analyses reveal a marked reduction of CD248-enriched secretory-reticular fibroblasts in diabetic wounds. We identify IGF-1 as a key regulator of CD248 expression through the protein kinase B/mTOR signaling pathway and the SP1 transcription factor. Overexpression of CD248 enhances fibroblast motility, elucidating the under-representation of CD248-enriched fibroblasts in diabetic wounds. Immunohistochemical staining of diabetic wound samples further confirms low SP1 expression and fewer CD248-positive secretory-reticular fibroblasts. Further investigation reveals that elevated TNFα levels in diabetic environment promotes IGF-1 resistance, and inhibiting IGF-1 induced CD248 expression. In summary, our findings underscore the critical role of the IGF1-SP1-CD248 axis in activating reticular fibroblasts during wound-healing processes. Targeting this axis in fibroblasts could help develop a therapeutic regimen for diabetic ulcers.

Emerging Techniques in Spatial Multiomics: Fundamental Principles and Applications to Dermatology

Molecular pathology, such as high-throughput genomic and proteomic profiling, identifies precise disease targets from biopsies but require tissue dissociation, losing valuable histologic and spatial context. Emerging spatial multi-omic technologies now enable multiplexed visualization of genomic, proteomic, and epigenomic targets within a single tissue slice, eliminating the need for labeling multiple adjacent slices. Although early work focused on RNA (spatial transcriptomics), spatial technologies can now concurrently capture DNA, genome accessibility, histone modifications, and proteins with spatially-resolved single-cell resolution. This review outlines the principles, advantages, limitations, and potential for spatial technologies to advance dermatologic research. By jointly profiling multiple molecular channels, spatial multiomics enables novel studies of copy number variations, clonal heterogeneity, and enhancer dysregulation, replete with spatial context, illuminating the skin's complex heterogeneity.

Epigallocatechin gallate and vancomycin loaded poly(vinyl)-pyrrolidone-gelatine nanofibers, conceivable curative approach for wound healing

During surgical procedures, skin and soft tissue wounds are often infected by resistant strains of gram-positive bacteria and gram-negative bacteria, resulting in serious obstacles to the healing of these wounds. Commercially available dressings for such wounds are still insufficient to combat resistant infections. Here, we designed vancomycin and epigallocatechin gallate (EGCG) loaded poly(vinyl)-pyrrolidone-gelatine nanofiber's membrane dressing for potential synergistic efficiency against infected post-surgical wounds. The nanofiber's membrane was physiochemically characterized by surface morphology, chemical and physical compatibilities', thermal stability, and drug release. Disk diffusion assays, Minimum inhibitor concentrations (MICs), and fractional inhibitory concentration indexes (FICI) were measured to analyze synergistic efficiency against Escherichia coli. Furthermore, Balb/c mice were used for in vivo healing studies, and to observe the healing mechanisms, histological assessments were performed. The designed system displayed excellent physical and chemical properties. The in vitro studies unveiled controlled-release patterns of vancomycin and EGCG and, at the same time, revealed 1.5-fold higher antimicrobial synergistic efficacy (FICI 0.485) than vancomycin against E. coli. The wound healing mechanisms reflected quick and mature healing processes with the promotion of collagen and angiogenesis at wound sites. The designed electrospun nanofiber technology might be personalized, rapid wound healing remedy for scientists and healthcare providers, and may enhance patients' outcomes and quality of life.

Mechanisms of Impaired Wound Healing in Type 2 Diabetes: The Role of Epigenetic Factors

Despite decades of research, impaired extremity wound healing in type 2 diabetes remains a significant driver of patient morbidity, mortality, and health care costs. Advances in surgical and medical therapies, including the advent of endovascular interventions for peripheral artery disease and topical therapies developed to promote wound healing, have not reduced the frequency of lower leg amputations for nonhealing wounds in type 2 diabetes. This brief report is aimed at reviewing the roles of various cell types in tissue repair and summarizing the known dysfunctions of these cell types in diabetic foot ulcers. Recent advances in our understanding of the epigenetic regulation in immune cells identified to be altered in type 2 diabetes are summarized, and particular attention is paid to the developing research defining the epigenetic regulation of structural cells, including keratinocytes, fibroblasts, and endothelial cells. Gaps in knowledge are highlighted, and potential future directions are suggested based on the current state of the field.

Mechanisms and therapeutic opportunities in metabolic aberrations of diabetic wounds: a narrative review

Metabolic aberrations are fundamental to the complex pathophysiology and challenges associated with diabetic wound healing. These alterations, induced by the diabetic environment, trigger a cascade of events that disrupt the normal wound-healing process. Key factors in this metabolic alternation include chronic hyperglycemia, insulin resistance, and dysregulated lipid and amino acid metabolism. In this review, we summarize the underlying mechanisms driving these metabolic changes in diabetic wounds, while emphasizing the broad implications of these disturbances. Additionally, we discuss therapeutic approaches that target these metabolic anomalies and how their integration with existing wound-healing treatments may yield synergistic effects, offering promising avenues for innovative therapies.

Dehydroabietic acid protects against cerebral ischaemia-reperfusion injury by modulating microglia-mediated neuroinflammation via targeting PKCδ

BACKGROUND AND PURPOSE

Cerebral ischaemia-reperfusion injury (CIRI) is a major contributor to global morbidity and mortality, although its underlying mechanisms remain only partly understood. Emerging evidence indicates that inhibiting microglia-mediated neuroinflammation would be an effective therapeutic approach for CIRI, and pharmacological interventions targeting this pathway hold significant therapeutic promise. This study aimed to identify a potent anti-inflammatory drug from a natural compound library as a potential treatment for CIRI.

EXPERIMENTAL APPROACH

We used oxygen-glucose deprivation/reperfusion (OGD/R) and middle cerebral artery occlusion in male C57BL/6 mice to evaluate the efficacy of DHA in neurological deficits and the anti-inflammatory effects. Using BV2 cells and murine brain tissue, liquid chromatography-tandem mass spectrometry was used to identify potential molecular targets of DHA, followed by bio-layer interferometry, molecular docking, molecular dynamics simulations and cellular thermal shift assays to validate DHA's binding interactions with protein kinase C delta (PKCδ).

KEY RESULTS

DHA decreased production of pro-inflammatory cytokines following OGD/R, thereby inhibiting microglia-mediated neuroinflammation to protect neurons and reducing brain infarct size and improving neurological outcomes. Mechanistically, DHA directly bound to PKCδ, inhibiting its phosphorylation and downstream NF-κB signalling. This binding interaction involved TRP55 and LEU106 on PKCδ, as confirmed by molecular docking and other biophysical techniques.

CONCLUSION AND IMPLICATIONS

DHA specifically interacts with PKCδ, preventing its phosphorylation induced by ischaemia-reperfusion injury. These results suggest that DHA is a novel inhibitor of PKCδ and provide solid experimental foundations for using DHA in treating neuroinflammation-related conditions, such as CIRI.

S100A9 as a promising therapeutic target for diabetic foot ulcers

BACKGROUND

Diabetic foot is a complex condition with high incidence, recurrence, mortality, and disability rates. Current treatments for diabetic foot ulcers are often insufficient. This study was conducted to identify potential therapeutic targets for diabetic foot.

METHODS

Datasets related to diabetic foot and diabetic skin were retrieved from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified using R software. Enrichment analysis was conducted to screen for critical gene functions and pathways. A protein interaction network was constructed to identify node genes corresponding to key proteins. The DEGs and node genes were overlapped to pinpoint target genes. Plasma and chronic ulcer samples from diabetic and non-diabetic individuals were collected. Western blotting, immunohistochemistry, and enzyme-linked immunosorbent assays were performed to verify the S100 calcium binding protein A9 (S100A9), inflammatory cytokine, and related pathway protein levels. Hematoxylin and eosin staining was used to measure epidermal layer thickness.

RESULTS

In total, 283 common DEGs and 42 node genes in diabetic foot ulcers were identified. Forty-three genes were differentially expressed in the skin of diabetic and non-diabetic individuals. The overlapping of the most significant DEGs and node genes led to the identification of S100A9 as a target gene. The S100A9 level was significantly higher in diabetic than in non-diabetic plasma (178.40 ± 44.65 ng/mL vs. 40.84 ± 18.86 ng/mL) and in chronic ulcers, and the wound healing time correlated positively with the plasma S100A9 level. The levels of inflammatory cytokines (tumor necrosis factor-α, interleukin [IL]-1, and IL-6) and related pathway proteins (phospho-extracellular signal regulated kinase [ERK], phospho-p38, phospho-p65, and p-protein kinase B [Akt]) were also elevated. The epidermal layer was notably thinner in chronic diabetic ulcers than in non-diabetic skin (24.17 ± 25.60 μm vs. 412.00 ± 181.60 μm).

CONCLUSIONS

S100A9 was significantly upregulated in diabetic foot and was associated with prolonged wound healing. S100A9 may impair diabetic wound healing by disrupting local inflammatory responses and skin re-epithelialization.

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.

Identification and validation of immune-related biomarkers and polarization types of macrophages in keloid based on bulk RNA-seq and single-cell RNA-seq analysis

INTRODUCTION

Keloids are a common complication that occurs after injury. The pathogenesis of this disease remains unknown. Therefore, identifying immune-related biomarkers and macrophage polarization types in keloids can provide new insights into their treatment.

METHODS

In this study, keloid-related bulk RNA-seq data (GSE83286, GSE212954, GSE92566, and GSE90051) were obtained from the Gene Expression Omnibus (GEO) database. The datasets GSE83286, GSE212964, and GSE92566 were combined to form a training set, while GSE90051 was utilized as an external validation set. Differentially expressed genes (DEGs) were detected by comparing keloid and normal samples within the training set. Differentially expressed immune-related genes (DIRGs) were then determined by intersecting the DEGs with immune-related genes (IRGs). Based on the protein-protein interaction (PPI) network, the top 40 DIRGs were selected for further analyses. Weighted Gene Co-expression Network Analysis (WGCNA), in conjunction with three machine learning techniques - least absolute shrinkage and selection operator (LASSO), support vector machine-recursive feature elimination (SVM-RFE), and random forest (RF) - employed to identify biomarkers. Subsequently, a nomogram model was constructed and validated. Single-cell RNA (scRNA) analysis was used to examine the expression of biomarkers at the cell-type level. Furthermore, since keloid is a chronic inflammatory disease and the abnormal polarization of macrophages is essential for the occurrence of this kind of disease, in this study we also endeavor to elucidate the state of macrophage polarization dysregulation within keloid, with the anticipation of generating novel concepts for the treatment of keloid. Finally, western blot (WB) and immunofluorescence (IF) analyses were carried out to confirm the expression levels of the biomarkers.

RESULTS

A total of 740 DEGs were identified in the training set, comprising 331 up-regulated genes and 409 down-regulated genes. After intersecting with the IRGs, 73 DIRGs were obtained. Subsequently, the top 40 DIRGs were chosen for further analysis. Eventually, two biomarkers, namely BMP1 and IL1R1, were identified through WGCNA and the three machine learning methods. Their expression levels were then verified by single-cell analysis, WB, and IF analysis. Additionally, it was found that the number of M2 macrophages significantly increased, while the number of M1 macrophages decreased in keloids compared to normal samples.

CONCLUSION

BMP1 and IL1R1 might function as novel biomarkers and potential therapeutic targets for keloid treatment. Moreover, upregulating M1 macrophages and downregulating M2 macrophages could represent a promising approach for the treatment of keloids.

Dynamic single-cell transcriptomic reveals the cellular heterogeneity and a novel fibroblast subpopulation in laryngotracheal stenosis

BACKGROUND

Laryngotracheal stenosis (LTS), a pathological narrowing of the upper airway caused by excessive extracellular matrix (ECM) deposition, often leads to dyspnea and even respiratory failure. However, systematic studies addressing the specific subpopulations and their contribution to LTS development still remain underexplored.

RESULTS

We collected laryngotracheal tissue at multiple time points of LTS rat model, established by injuring their laryngotracheal lining, and performed dynamic single-cell RNA sequencing (scRNA-seq) to elucidate the transcriptomic atlas of LTS development. The results showed, from the inflammatory state to the repair/fibrotic state, infiltration of immune cells such as monocyte macrophages decreased and fibroblast increased. We delineated the markers and functional status of different fibroblasts subsets and identified that fibrotic fibroblasts may originate from multiple fibroblast subpopulations, including a new subpopulation characterized by the expression of chondrogenic markers such as Ucma and Col2a1, we designated this subcluster as chondrocyte injury-related fibroblasts (CIRF). Furthermore, we categorized monocytes/macrophages into several subtypes and identified that SPP1 high macrophages represented the largest macrophage subpopulation in LTS, providing evidence to clarify the importance of SPP1 macrophages in fibrosis disease. Our findings also revealed the interactions among these cells to explore the molecular mechanism associated with LTS pathogenesis.

CONCLUSIONS

Our study, for the first time, conducted dynamic scRNA-seq on LTS, revealing the cellular heterogeneity and providing a valuable resource for exploring the intricate molecular landscape of LTS. We propose CIRF may represent a tissue-specific fibroblast lineage in LTS and potentially originate from cells in the perichondrium of the trachea and transform into fibrotic fibroblasts. Integration of our study with those of other respiratory fibrotic diseases will allow for a comprehensive understanding of airway remodeling in respiratory diseases and exploring potential new therapeutic targets for their treatment.

Microenvironment of diabetic foot ulcers: Implications for healing and therapeutic strategies

Diabetic foot ulcers (DFUs) are a common yet serious complication in individuals with diabetes, often presenting as chronic, nonhealing wounds that significantly impair quality of life. The healing process of DFUs is largely influenced by the local microenvironment, which encompasses factors such as hypoxia, inflammation, and the involvement of various cell types. Poor blood circulation in the affected area results in hypoxia, compromising cellular function and restricting nutrient supply, thereby delaying wound healing. In addition, chronic inflammation disrupts immune system balance, with excessive pro-inflammatory cytokines not only failing to facilitate tissue repair but also exacerbating tissue damage. Moreover, key cell types, including fibroblasts, keratinocytes, and macrophages, play crucial roles at different stages of the healing process, contributing to collagen production and skin regeneration. A comprehensive understanding of the complex dynamics within the DFU microenvironment is essential for developing more precise therapeutic approaches, such as advanced drug delivery systems and bioactive materials, aimed at promoting wound healing and reducing the risk of recurrence.

Analysis and Validation of Mitophagy-Related Genes in Diabetic Foot Ulcers

Purpose

This study aimed to identify hub genes associated with mitophagy involved in the pathogenesis and progression of diabetic foot ulcer (DFU), and to characterize their immune cell infiltration features and single-cell expression profiles.

Methods

DFU-related datasets (GSE80178, GSE68183) were retrieved from the GEO database. Subsequently, differentially expressed genes (DEGs) were identified via limma analysis, followed by gene set enrichment analysis (GSEA) to assess gene function enrichment. Identified DEGs were intersected with mitophagy-related genes. Machine learning (ML) algorithms were further employed to identify hub genes. Additionally, immune cell infiltration was examined via the CIBERSORT algorithm, and the correlation between the identified genes and immune infiltration was investigated. Finally, hub genes identified were validated via the single-cell RNA sequencing dataset GSE165816, and further validated using RT-PCR and Western blot (WB) assays.

Results

Two hub genes, ANO6 and ALDH2, were identified and found to be significantly downregulated in the skin tissues of patients with DFU. Receiver operating characteristic (ROC) analysis demonstrated robust diagnostic potential (ANO6, AUC = 0.833, ALDH2, AUC = 0.806). Immune cell infiltration analysis demonstrated notable differences between the DFU and normal groups in naïve B cells, monocytes, resting mast cells, γδT cells, and regulatory T cells (Tregs). The findings were further validated through single-cell RNA sequencing (scRNA-seq) analysis and experimental studies, which confirmed the downregulation of ANO6 and ALDH2 in DFU tissues.

Conclusion

Two mitophagy-related hub genes, ANO6 and ALDH2, were identified and validated as being significantly downregulated in DFU. Both genes demonstrated diagnostic potential and showed an association with immune cell infiltration. These findings suggest that mitophagy dysfunction may contribute to the pathophysiology of DFU, potentially through the dysregulation of inflammatory pathways and immune responses. While the results provide valuable insights into DFU and its management, further studies with larger cohorts and deeper exploration of mechanistic links to inflammation are necessary to translate these findings into therapeutic strategies.

Single-cell RNA sequencing reveals a new mechanism of endothelial cell heterogeneity and healing in diabetic foot ulcers

Diabetic foot ulcers (DFU) are a common and severe complication among diabetic patients, posing a significant burden on patients' quality of life and healthcare systems due to their high incidence, amputation rates, and mortality. This study utilized single-cell RNA sequencing technology to deeply analyze the cellular heterogeneity of the skin on the feet ofDFU patients and the transcriptomic characteristics of endothelial cells, aiming to identify key cell populations and genes associated with the healing and progression of DFU. The study found that endothelial cells from DFU patients exhibited significant transcriptomic differences under various conditions, particularly in signaling pathways related to inflammatory responses and angiogenesis. Through trajectory analysis and cell communication research, we revealed the key role of endothelial cell subsets in the development of DFU and identified multiple important gene modules associated with the progression of DFU. Notably, the promoting effect of the SH3BGRL3 gene on endothelial cell proliferation, migration, and angiogenic capabilities under high glucose conditions was experimentally verified, providing a new potential target and theoretical basis for the treatment of DFU. This study not only enhances the understanding of the pathogenesis ofDFU but also provides a scientific basis for the development ofnew therapeutic strategies.

Corilagin enhances wound healing by modulating the macrophage phenotype in diabetic mice

Excessive inflammation is a prominent issue in diabetic wounds, leading to delayed healing or amputation. Corilagin (Cori) is a natural polyphenolic compound with diverse pharmacological activities, particularly its anti-inflammatory properties. The aim of this study was to evaluate the anti-inflammatory effect of Cori on diabetic wounds and to explore the potential underlying mechanisms. The impact of Cori on wound healing was assessed in streptozotocin (STZ)-induced diabetic mice through morphological observation, histological staining, and gene expression analysis. Flow cytometry, qRT-PCR, western blot analysis, and RNA sequencing were conducted to elucidate the underlying mechanisms in RAW264.7 cells. The results demonstrated that Cori accelerated wound healing, inhibited excessive inflammation, and regulated macrophage polarization in diabetic mice. In Vitro, Cori decreased M1 polarization and inhibited the expression of pro-inflammatory mediators in RAW264.7 cells. Sequencing analysis revealed that Cori exerts anti-inflammatory effects on RAW 264.7 cells through multiple targeted mechanisms. Moreover, in LPS-induced macrophages, Cori dramatically decreased the activation of TLR4, MyD88, and NF-κB. Additionally, Cori enhanced M2 polarization by promoting fatty acid oxidation. In conclusion, the findings suggest that Cori modulates macrophage polarization through various targeted mechanisms, effectively suppressing inflammation and accelerating diabetic wound healing.

Insights into the molecular underpinning of type 2 diabetes complications

Type 2 diabetes (T2D) complications pose a significant global health challenge. Omics technologies have been employed to investigate these complications and identify the biological pathways involved. In this review, we focus on four major T2D complications: diabetic kidney disease, diabetic retinopathy, diabetic neuropathy, and cardiovascular complications. We discuss advancements in omics research, summarizing findings from genetic, epigenomic, transcriptomic, proteomic, and metabolomic studies across different ancestries and disease-relevant tissues. We stress the importance of integrating multi-omics techniques to elucidate the biological mechanisms underlying T2D complications and advocate for ancestrally diverse studies. Ultimately, these insights will improve risk prediction for T2D complications and inform translation strategies.

Spatiotemporal single-cell roadmap of human skin wound healing

Wound healing is vital for human health, yet the details of cellular dynamics and coordination in human wound repair remain largely unexplored. To address this, we conducted single-cell multi-omics analyses on human skin wound tissues through inflammation, proliferation, and remodeling phases of wound repair from the same individuals, monitoring the cellular and molecular dynamics of human skin wound healing at an unprecedented spatiotemporal resolution. This singular roadmap reveals the cellular architecture of the wound margin and identifies FOSL1 as a critical driver of re-epithelialization. It shows that pro-inflammatory macrophages and fibroblasts sequentially support keratinocyte migration like a relay race across different healing stages. Comparison with single-cell data from venous and diabetic foot ulcers uncovers a link between failed keratinocyte migration and impaired inflammatory response in chronic wounds. Additionally, comparing human and mouse acute wound transcriptomes underscores the indispensable value of this roadmap in bridging basic research with clinical innovations.

Tissue nanotransfection-based endothelial PLCγ2-targeted epigenetic gene editing rescues perfusion and diabetic ischemic wound healing

Diabetic wounds are complicated by underlying peripheral vasculopathy. Reliance on vascular endothelial growth factor (VEGF) therapy to improve perfusion makes logical sense, yet clinical study outcomes on rescuing diabetic wound vascularization have yielded disappointing results. Our previous work has identified that low endothelial phospholipase Cγ2 (PLCγ2) expression hinders the therapeutic effect of VEGF on the diabetic ischemic limb. In this work, guided by single-cell RNA sequencing of human wound edge, we test the efficacy of gene-targeted therapeutic demethylation intending to improve VEGF-mediated neovascularization. PLCγ2 expression was diminished in all five identified diabetic wound-edge endothelial subclusters encompassing arterial, venous, and capillary cells. Such low expression was associated with hypermethylated PLCγ2 promoter. PLCγ2 promoter was also hypermethylated at murine diabetic ischemic wound edge. To specifically demethylate endothelial PLCγ2 promoter during VEGF therapy, a CRISPR-dCas9-based demethylation cocktail was delivered to the ischemic wound edge using tissue nanotransfection (TNT) technology. Demethylation-based upregulation of PLCγ2 during VEGF therapy improved wound tissue blood flow with an increased abundance of von Willebrand factor (vWF)+/PLCγ2+ vascular tissue elements by activating p44/p42-mitogen-activated protein kinase (MAPK) → hypoxia-inducible factor [HIF]-1α pathway. Taken together, TNT-based delivery of plasmids to demethylate the PLCγ2 gene promoter activity led to significant improvements in VEGF therapy for cutaneous diabetic wounds, resulting in better perfusion and accelerated wound closure.

Scupa: single-cell unified polarization assessment of immune cells using the single-cell foundation model

MOTIVATION

Immune cells undergo cytokine-driven polarization in response to diverse stimuli, altering their transcriptional profiles and functional states. This dynamic process is central to immune responses in health and diseases, yet a systematic approach to assess cytokine-driven polarization in single-cell RNA sequencing data has been lacking.

RESULTS

To address this gap, we developed single-cell unified polarization assessment (Scupa), the first computational method for comprehensive immune cell polarization assessment. Scupa leverages data from the Immune Dictionary, which characterizes cytokine-driven polarization states across 14 immune cell types. By integrating cell embeddings from the single-cell foundation model Universal Cell Embeddings, Scupa effectively identifies polarized cells across different species and experimental conditions. Applications of Scupa in independent datasets demonstrated its accuracy in classifying polarized cells and further revealed distinct polarization profiles in tumor-infiltrating myeloid cells across cancers. Scupa complements conventional single-cell data analysis by providing new insights into dynamic immune cell states, and holds potential for advancing therapeutic insights, particularly in cytokine-based therapies.

AVAILABILITY AND IMPLEMENTATION

The code is available at https://github.com/bsml320/Scupa.

Single-cell RNA sequencing reveals the impaired epidermal differentiation and pathological microenvironment in diabetic foot ulcer

Background

Diabetic foot ulcer (DFU) is one of the most common and complex complications of diabetes, but the underlying pathophysiology remains unclear. Single-cell RNA sequencing (scRNA-seq) has been conducted to explore novel cell types or molecular profiles of DFU from various perspectives. This study aimed to comprehensively analyze the potential mechanisms underlying impaired re-epithelization of DFU in a single-cell perspective.

Methods

We conducted scRNA-seq on tissues from human normal skin, acute wound, and DFU to investigate the potential mechanisms underlying impaired epidermal differentiation and the pathological microenvironment. Pseudo-time and lineage inference analyses revealed the distinct states and transition trajectories of epidermal cells under different conditions. Transcription factor analysis revealed the potential regulatory mechanism of key subtypes of keratinocytes. Cell-cell interaction analysis revealed the regulatory network between the proinflammatory microenvironment and epidermal cells. Laser-capture microscopy coupled with RNA sequencing (LCM-seq) and multiplex immunohistochemistry were used to validate the expression and location of key subtypes of keratinocytes.

Results

Our research provided a comprehensive map of the phenotypic and dynamic changes that occur during epidermal differentiation, alongside the corresponding regulatory networks in DFU. Importantly, we identified two subtypes of keratinocytes: basal cells (BC-2) and diabetes-associated keratinocytes (DAK) that might play crucial roles in the impairment of epidermal homeostasis. BC-2 and DAK showed a marked increase in DFU, with an inactive state and insufficient motivation for epidermal differentiation. BC-2 was involved in the cellular response and apoptosis processes, with high expression of TXNIP, IFITM1, and IL1R2. Additionally, the pro-differentiation transcription factors were downregulated in BC-2 in DFU, indicating that the differentiation process might be inhibited in BC-2 in DFU. DAK was associated with cellular glucose homeostasis. Furthermore, increased CCL2 + CXCL2+ fibroblasts, VWA1+ vascular endothelial cells, and GZMA+CD8+ T cells were detected in DFU. These changes in the wound microenvironment could regulate the fate of epidermal cells through the TNFSF12-TNFRSF12A, IFNG-IFNGR1/2, and IL-1B-IL1R2 pathways, which might result in persistent inflammation and impaired epidermal differentiation in DFU.

Conclusions

Our findings offer novel insights into the pathophysiology of DFU and present potential therapeutic targets that could improve wound care and treatment outcomes for DFU patients.

Exosome-carried miR-1248 from adipose-derived stem cells improves angiogenesis in diabetes-associated wounds

Chronic non-healing wounds are a common complication of diabetes, marked by impaired angiogenesis. This study explores how exosomes (Exo-miR-1248) from miR-1248-overexpressing adipose-derived stem cells enhance diabetic wound healing by modulating endothelial cell function. Adipose-derived stem cells were transfected with a lentivirus carrying miR-1248 to produce Exo-miR-1248, isolated via differential centrifugation. In vitro, Exo-miR-1248's effects on proliferation, scratch wound healing, and tube formation in human umbilical vein endothelial cells (HUVECs) were assessed. For in vivo analysis, diabetic mice were induced with streptozotocin (STZ) and full-thickness skin defects were created. The impact of Exo-miR-1248 on wound healing was evaluated through subcutaneous injections. Histological analysis included H&E staining for epithelial regeneration and wound width, Masson's staining for collagen deposition, immunofluorescence for CD31 and α-SMA expression, RT-qPCR and WB for mRNA and protein levels of pro-angiogenic genes (VEGF-A, TGF-β, and Angpt-1). Exo-miR-1248 significantly enhanced HUVEC proliferation and migration. Tube formation assays showed increased capillary-like structures. In vivo, Exo-miR-1248-treated wounds healed faster, with improved collagen deposition and blood vessel formation. RT-qPCR and WB show that the mRNA and protein levels of VEGF-A, Angpt-1, and TGF-β are upregulated. Exo-miR-1248 may enhance diabetic wound healing by upregulating pro-angiogenic factors, offering a novel therapeutic approach.

Integrated Single-Cell Analysis Reveals Spatially and Temporally Dynamic Heterogeneity in Fibroblast States during Wound Healing

Wound healing is a dynamic process over temporal and spatial scales. Key to repair outcomes are fibroblasts; yet, how they modulate healing across time and in different wound regions remains incompletely understood. By integrating single-cell RNA-sequencing datasets of mouse skin and wounds, we infer that fibroblasts are the most transcriptionally dynamic skin-resident cells, evolving during postnatal skin maturation and rapidly after injury toward distinct late scar states. We show that transcriptional dynamics in fibroblasts are largely driven by genes encoding extracellular matrix and signaling factors. Lineage trajectory inference and spatial gene mapping reveal that Prg4-expressing fibroblasts transiently emerge along early wound edges. Within days, they become replaced by long-lasting and likely noninterconverting fibroblast populations, including Col25a1-expressing and Pamr1-expressing fibroblasts that occupy subepidermal and deep scar regions, respectively, where they engage in reciprocal signaling with immune cells. Signaling inference shows that fibroblast-immune crosstalk repeatedly uses some signaling pathways across wound healing time, whereas use of other signaling pathways is time and space limited. Collectively, we uncovered high transcriptional plasticity by wound fibroblasts, with early states transiently forming distinct microniches along wound edges and in the fascia, followed by stable states that stratify scar tissue into molecularly dissimilar upper and lower layers.

Extracellular Mitochondrial-Derived Vesicles Affect the Progression of Diabetic Foot Ulcer by Regulating Oxidative Stress and Mitochondrial Dysfunction

Diabetic foot ulcer (DFU) is a common and severe complication of diabetes mellitus, the etiology of which remains insufficiently understood, particularly regarding the involvement of extracellular vesicles (EVs). In this study, nanoflow cytometry to detect EVs in DFU skin tissues is used and found a significant increase in the Translocase of Outer Mitochondrial Membrane 20 (TOM20)+ mitochondrial-derived vesicles (MDVs). The role of MDVs in DFU is yet to be reported. Using single-cell datasets, it is discovered that the increase in MDVs may be regulated by Sorting Nexin 9 (SNX9). In vitro experiments revealed that MDVs secreted by fibroblasts cultured in high glucose medium exhibited similar composition and protein enrichment results to those in DFU tissues, suggesting their potential as an ideal in vitro surrogate. These MDVs promoted apoptosis and intracellular oxidative stress, disrupted mitochondrial structure, and reduced aerobic metabolism in target cells. In vivo experiments also showed that MDV drops hindered wound healing in diabetic mice; however, this effect is rescued by SNX9 inhibitors, restoring mitochondrial dynamics and balance. Under high glucose conditions, MDVs significantly upregulated oxidative stress levels and induced mitochondrial dysfunction. This study proposes targeting MDVs as a potential therapeutic strategy for DFU.

How Can Spatial Transcriptomic Profiling Advance Our Understanding of Skin Diseases?

Spatial transcriptomic (ST) profiling is the mapping of gene expression within cell populations with preservation of positional context and represents an exciting new approach to develop our understanding of local and regional influences upon skin biology in health and disease. With the ability to probe from a few hundred transcripts to the entire transcriptome, multiple ST approaches are now widely available. In this paper, we review the ST field and discuss its application to dermatology. Its potential to advance our understanding of skin biology in health and disease is highlighted through the illustrative examples of 3 research areas: cutaneous aging, tumorigenesis, and psoriasis.

Exosomes derived from fibroblasts in DFUs delay wound healing by delivering miR-93-5p to target macrophage ATG16L1

Diabetes is an extremely costly disease, one-third of which are attributed to the management of diabetic foot disease including chronic, non-healing, diabetic foot ulcers (DFUs). Therefore, much effort is needed to understand the pathogenesis of DFUs and novel therapeutics. We utilized exosome staining to confirm the interaction between fibroblast-derived exosomes and macrophages. Subsequently, we employed public data and qPCR to screen for upregulated miRNAs in fibroblast-derived exosomes in DFUs. The relationship between was validate miR-93-5 and ATG16L1 through data prediction and dual-luciferase reporter assays. A variety of molecular biology experiments were used for subsequent pathway validation. Additionally, we established Atg16l1MKI and Nlrp3MKO mice for further validation. We identified that miR-93-5p derived from fibroblasts played an important role in M1 macrophages polarization. Predicted by database, we found that miR-93-5p can bind to ATG16L1 mRNA, thereby influencing macrophage autophagy mediated by ATG16L1 in the clearance of ROS, thus activating the NLRP3 signaling pathway. In vivo, miR-93-5p antagomir treatment accelerated diabetic wound healing and induced M2 macrophage polarization. Fibroblasts and macrophages show cell crosstalk during the development of DFUs by miR-93-5p, and that antagomir treatment may be a promising and technically advantageous alternative to DFUs therapies.

Heterogeneous porous hypoxia-mimicking scaffolds propel urethral reconstruction by promoting angiogenesis and regulating inflammation

The nasty urine microenvironment (UME) impedes neourethral regeneration by inhibiting angiogenesis and inducing an excessive inflammatory response. Cellular adaptation to hypoxia improves regeneration in numerous tissues. In this study, heterogeneous porous hypoxia-mimicking scaffolds were fabricated for urethral reconstruction via promoting angiogenesis and modulating the inflammatory response based on sustained release of dimethyloxalylglycine (DMOG) to promote HIF-1α stabilization. Such scaffolds exhibit a two-layered structure: a dense layer composed of electrospun poly (l-lactic acid) (PLLA) nanofibrous mats and a loose layer composed of a porous gelatin matrix incorporated with DMOG-loaded mesoporous silica nanoparticles (DMSNs) and coated with poly(glycerol sebacate) (PGS). The modification of PGS could significantly increase rupture elongation, making the composite scaffolds more suitable for urethral tissue regeneration. Additionally, sustained release of DMOG from the scaffold facilitates proliferation, migration, tube formation, and angiogenetic gene expression in human umbilical vein endothelial cells (HUVECs), as well as stimulates M2 macrophage polarization and its regulation of HUVECs migration and smooth muscle cell (SMCs) contractile phenotype. These effects were downstream of the stabilization of HIF-1α in HUVECs and macrophages under hypoxia-mimicking conditions. Furthermore, the scaffold achieved better urethral reconstruction in a rabbit urethral stricture model, including an unobstructed urethra with a larger urethral diameter, increased regeneration of urothelial cells, SMCs, and neovascularization. Our results indicate that heterogeneous porous hypoxia-mimicking scaffolds could promote urethral reconstruction via facilitating angiogenesis and modulating inflammatory response.

Development of a Cellular Assay as a Personalized Model for Testing Chronic Wound Therapeutics

Exudates of nonhealing wounds contain drivers of pathogenicity. We utilized >800 exudates from nonhealing and healing wounds of diverse etiologies, collected by 3 different methods, to develop a wound-specific, cell-based functional biomarker assay. Human dermal fibroblast proliferation served as readout to (i) differentiate between healing and nonhealing wounds, (ii) follow the healing process of individual patients, and (iii) assess the effects of therapeutics for chronic wounds ex vivo. We observed a strong correlation between wound chronicity and inhibitory effects of individual exudates on fibroblast proliferation, with good diagnostic sensitivity (76-90%, depending on the sample collection method). Transition of a clinically nonhealing to a healing phenotype restored fibroblast proliferation and extracellular matrix formation while reducing inflammatory cytokine production. Transcriptional analysis of fibroblasts exposed to ex vivo nonhealing wound exudates revealed an induction of inflammatory cytokine and chemokine pathways and the unfolded protein response, indicating that these changes may contribute to the pathology of nonhealing wounds. Testing the wound therapeutics, PDGF and silver sulfadiazine, yielded responses in line with clinical experience and indicates the usefulness of the assay to search for and profile new therapeutics.

Single-Cell Analysis of Debrided Diabetic Foot Ulcers Reveals Dysregulated Wound Healing Environment in Non-Hispanic Black Patients

Diabetic foot ulcer is a critical complication of diabetes, but the wound microenvironment and its healing process are not completely understood. In this study, we optimized single-cell profiling from sharp debrided ulcers. Our findings demonstrate that healing diabetic foot ulcers were significantly enriched with distinct fibroblasts-expressing genes related to inflammation (CHI3L1, IL6) and extracellular matrix remodeling (ASPN), validating our previous studies on surgically resected ulcers. The race-focused analysis depicted lower expression of key healing-associated genes such as CHIL3L1, matrix metalloproteinase 11 gene MMP11, and SFRP4 in fibroblasts of non-Hispanic Black patients than in those of White patients. In cellular communication analysis, healing-enriched fibroblasts of non-Hispanic Black patients exhibited upregulation of signaling pathways such as WNT, whereas those of White patients showed insulin-like GF and Midkine pathways upregulation. Our findings advocate race as a risk marker of diabetic foot ulcer outcomes, likely reflecting underlying disparities in environmental exposures and access to care that profoundly influence healing markers. Using sharp debrided tissues for single-cell assays, this study highlights the need for in-depth investigations into dysregulated wound healing microenvironments of under-represented racial groups.

Adipose-Derived Stem Cell Exosomes Promote Scar-Free Healing of Diabetic Wounds via miR-204-5p/TGF-β1/Smad Pathway

Numerous researches have demonstrated the therapeutic potential of adipose-derived stem cell exosomes (ADSC-Exos) in promoting wound healing. In this study, we aimed to investigate the impact of ADSC-Exos on diabetic wound fibroblasts and elucidate its possible mechanisms. CCK-8, Edu, cell scratch, and Transwell tests were used to evaluate the function of ADSC-Exos on rat skin fibroblasts (RSFs) in high-glucose (HG) medium. The targeting effect of ADSC-Exo-derived microRNA (miRNA) and TGF-β1 was assessed using bioinformatic analysis and then confirmed with western blot and dual luciferase reporter assays. ADSC-Exos, miR-204-5p mimic, and anti-miR-204-5p mimic were used to stimulate RSFs, and the levels of TGF-β1/Smad pathway were analyzed by western blot. In vivo, digital photo and tissue section staining were used to evaluate the therapeutic effect of ADSC-Exos on diabetic wounds. The data showed that ADSC-Exos enhance the proliferation and migration of fibroblasts under HG conditions, reduce excessive myofibroblast differentiation and collagen deposition, and promote scarless healing of diabetic wounds. Additionally, miR-204-5p in ADSC-Exos targets TGF-β1 to inhibit p-Smad2/3, Col I, and alpha-smooth muscle actin (α-SMA), thereby reducing fibrosis. These findings suggest that ADSC-Exos have potential prospects for promoting diabetic wound healing.

Tailored bioengineering and nanomedicine strategies for sex-specific healing of chronic wounds

Chronic wounds, defined by their prolonged healing process, significantly impair patients' quality of life and impose a hefty financial burden on healthcare systems worldwide. Sex- and gender-specific mechanisms regulate inflammation and infection, angiogenesis, matrix synthesis and cell recruitment. All of these processes contribute to cutaneous wound healing but remain largely understudied. This review aims to spotlight the innovative realm of bioengineering and nanomedicine, which is at the helm of revolutionizing complex chronic wound care. It underscores the significance of integrating patient sex into the development and (pre)clinical testing of these avant-garde treatment modalities, in order to enhance healing prospects for all patients regardless of sex. Moreover, we explore the representation of male and female patients in clinical trials of bioengineered and nanomedicine products. Finally, we examine the primary reasons for the historical neglect in translating sex-specific wound healing research into clinical practice and propose strategic solutions. By tackling these issues, the article advocates advanced treatment frameworks that could significantly improve healing outcomes for individuals of all sexes, thereby optimizing both efficacy and inclusivity in chronic wound management.

Chronic Wound Initiation: Single-Cell RNAseq of Cutaneous Wound Tissue and Contributions of Oxidative Stress to Initiation of Chronicity

Chronic wounds (CWs) in humans affect millions of people in the US alone, cost billions of dollars, cause much suffering, and still there are no effective treatments. Patients seek medical care when wound chronicity is already established, making it impossible to investigate factors that initiate chronicity. In this study, we used a diabetic mouse model of CWs that mimics many aspects of chronicity in humans. We performed scRNAseq to compare the cell composition and function during the first 72 h post-injury and profiled 102,737 cells into clusters of all major cell types involved in healing. We found two types of fibroblasts. Fib 1 (pro-healing) was enriched in non-CWs (NCWs) whereas Fib 2 (non-healing) was in CWs. Both showed disrupted proliferation and migration, and extracellular matrix (ECM) deposition in CWs. We identified several subtypes of keratinocytes, all of which were more abundant in NCWs, except for Channel-related keratinocytes, and showed altered migration, apoptosis, and response to oxidative stress (OS) in CWs. Vascular and lymphatic endothelial cells were both less abundant in CWs and both had impaired migration affecting the development of endothelial and lymphatic microvessels. Study of immune cells showed that neutrophils and mast cells are less abundant in CWs and that NCWs contained more proinflammatory macrophages (M1) whereas CWs were enriched in anti-inflammatory macrophages (M2). Also, several genes involved in mitochondrial function were abnormally expressed in CWs, suggesting impaired mitochondrial function and/or higher OS. Heat shock proteins needed for response to OS were downregulated in CWs, potentially leading to higher cellular damage. In conclusion, the initiation of chronicity is multifactorial and involves various cell types and cellular functions, indicating that one type of treatment will not fix all problems, unless the root cause is fundamental to the cell and molecular mechanisms of healing. We propose that such a fundamental process is high OS and its association with wound infection/biofilm.

Out of this World: Wound Healing on Earth and in Space

Impaired wound healing is a significant concern for humans in space, where the unique microgravity environment poses challenges to the natural healing processes of the body. Similar to chronic wounds on earth, such as diabetic foot ulcers and venous leg ulcers, wounds inflicted in space exhibit delayed or impaired healing responses. These wounds share common features, including dysregulated cellular signaling, altered cytokine profiles, and impaired tissue regeneration. Little is known about the mechanisms underlying wound healing under microgravity. In this review, we focused on exploring the parallels between wound healing in space and chronic wounds on earth as a fundamental approach for developing effective countermeasures to promote healing and mitigate associated health risks during long-space missions.

Fetal Skin Wound Healing: Key Extracellular Matrix Components and Regulators in Scarless Healing

Fetal skin at early gestational stage is able to regenerate and heal rapidly after wounding. The exact mechanisms and molecular pathways involved in this process are however still largely unknown. The numerous differences in the skin of the early fetus versus skin in later developmental stages might provide clues for the mechanisms of scarless healing. This review summarizes the differences between mammalian fetal skin and the skin at later developmental phases in healthy and wounded conditions, focusing on extracellular matrix components, which are crucial factors in the microenvironment that direct cells and tissue functions and hence the wound healing process.

In-Situ Electrospinning Dressings Loaded with Kaempferol for Reducing MMP9 to Promote Diabetic Ulcer Healing

Background

Diabetic foot ulcers (DFUs) are often associated with persistent inflammatory response, impaired macrophage polarization, and slow vascular regeneration. Existing treatments cannot be adapted to wounds and do not achieve the desired therapeutic effects. The high porosity of biomaterials induces more M2 macrophages, while the natural compound kaempferol inhibits the expression of matrix metalloproteinase 9 (MMP9) and thus inhibits the associated inflammatory and immunological responses.

Methods

portable electrospinning dressings (PEDs) were prepared from the spinning solution using a portable electrospinning device. The material properties of PEDs were examined by scanning electron microscope, contact angle tester and WVTR-C3. Then, the in vitro biocompatibility of the dressings was evaluated using NIH3T3 cells. The in vivo wound healing efficacy of the dressings was analyzed in the diabetic wound model rats. Histological and immunofluorescence staining were performed to determine the status of epithelization, collagen deposition, MMP9 expression, macrophage polarization, inflammation response and angiogenesis.

Results

Material science experiments have shown that the dressing has optimal fiber micromorphology and good water vapor transport properties (WVTR: 4.88 kg m-2 24h-1); in vivo, diabetic wound experiments have shown that the high porosity and pharmacological effects of PED4 can mutually promote the rapid healing of diabetic wounds (healed 95.9% on day 15), facilitate the transformation of macrophages from M1-type to M2-type and regulate the expression of MMP9.

Conclusion

Portable electrospinning dressings equipped with kaempferol not only better fit irregular wounds, but also promote wound healing through MMP9 and macrophage polarization. Thus, PEDs show great promise for advancing research of personalized diabetic wound healing.

Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor Roxadustat Accelerates Wound Healing in a Mouse Hind limb Lymphedema Model

Objective: Drugs regulating hypoxia-inducible factor (HIF)-1α have not been investigated for wound healing in lymphedema. Therefore, we examined the effects of drug modulation of HIF-1α activity for wound healing in our previously developed mouse model of nonirradiated hind limb lymphedema. Approach: Mouse hind limb lymphedema models (n = 17) and a sham group (n = 6) were created using 8- to 10-week-old male C57BL/6N mice. Mice with hind limb lymphedema were randomized into experimental groups receiving roxadustat, 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1), or dimethyl sulfoxide and were given intraperitoneal injections every 2 days for up to 2 weeks. Four days after the surgery, an 8-mm diameter full-thickness skin wound was created in the hind limb. The number of days required for wound closure and the percentage of wounds closed were measured. Skin samples taken at wound creation were evaluated by histological and molecular analysis. Results: Administration of roxadustat accelerated wound healing, whereas YC-1 delayed it, with a significant decrease and increase in skin thickness, respectively. The relative mRNA expression of Hif1α, matrix metalloproteinase-3, and interleukin-6 was significantly higher in the roxadustat group and that of metalloproteinase-9 was significantly lower in the roxadustat group compared with the control group. Innovation: This study is the first to demonstrate delayed wound healing in a mouse model of hind limb lymphedema and the first to demonstrate the promotion of significant wound healing through the use of roxadustat. Conclusion: Roxadustat exerts wound-healing effects and may promote the regulation of extracellular matrix remodeling via gene expression in hind limb lymphedema wound models.

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.

Spatial Transcriptomics in Inflammatory Skin Diseases Using GeoMx Digital Spatial Profiling: A Practical Guide for Applications in Dermatology

The spatial organization of the skin is critical for its function. In particular, the skin immune microenvironment is arranged spatially and temporally, such that imbalances in the immune milieu are indicative of disease. Spatial transcriptomic platforms are helping to provide additional insights into aberrant inflammation in tissues that are not captured by tissue processing required for single-cell RNA sequencing. In this paper, we discuss a technical and user experience overview of NanoString's GeoMx Digital Spatial Profiler to perform in-depth spatial analysis of the transcriptome in inflammatory skin diseases. Our objective is to provide potential pitfalls and methods to optimize RNA capture that are not readily available in the manufacturer's guidelines. We use concrete examples from our experiments to demonstrate these strategies in inflammatory skin diseases, including psoriasis, lichen planus, and discoid lupus erythematosus. Overall, we hope to illustrate the potential of digital spatial profiling to dissect skin disease pathogenesis in a spatially resolved manner and provide a framework for other skin biology investigators using digital spatial profiling.

Novel integrated multiomics analysis reveals a key role for integrin beta-like 1 in wound scarring

Exacerbation of scarring can originate from a minority fibroblast population that has undergone inflammatory-mediated genetic changes within the wound microenvironment. The fundamental relationship between molecular and spatial organization of the repair process at the single-cell level remains unclear. We have developed a novel, high-resolution spatial multiomics method that integrates spatial transcriptomics with scRNA-Seq; we identified new characteristic features of cell-cell communication and signaling during the repair process. Data from PU.1-/- mice, which lack an inflammatory response, combined with scRNA-Seq and Visium transcriptomics, led to the identification of nine genes potentially involved in inflammation-related scarring, including integrin beta-like 1 (Itgbl1). Transgenic mouse experiments confirmed that Itgbl1-expressing fibroblasts are required for granulation tissue formation and drive fibrogenesis during skin repair. Additionally, we detected a minority population of Acta2high-expressing myofibroblasts with apparent involvement in scarring, in conjunction with Itgbl1 expression. IL1β signaling inhibited Itgbl1 expression in TGFβ1-treated primary fibroblasts from humans and mice. Our novel methodology reveal molecular mechanisms underlying fibroblast-inflammatory cell interactions that initiate wound scarring.

Elevated EBF2 in mouse but not pig drives the progressive brown fat lineage specification via chromatin activation

Brown adipose tissue (BAT) is responsible for non-shivering thermogenesis, but it is absent in some mammals, including pigs. During development, BAT progenitors are derived from paired box 7 (Pax7)-expressing somitic mesodermal stem cells, which also give rise to skeletal muscle. However, the intrinsic mechanisms underlying the fate decisions between brown fat and muscle progenitors remain elusive across species. In this study, we analyzed the dynamics of chromatin landscape during the segregation and specification of brown fat and muscle lineages from Pax7+ multipotent mesodermal stem cells, aiming to uncover epigenetic factors that drive de novo BAT formation. Notably, myogenic progenitors were specified at embryonic day (E) 12.5, exhibiting high levels of H3K4me3 and low H3K27me3 at muscle-related genes. In contrast, the specification of the BAT lineage occurred much later, with coordinated step-wise depositions of histone modifications at BAT-associated genes from E10.5 to E14.5. We identified the transcription factor early B-cell factor 2 (EBF2) as a key driver of the progressive specification of brown fat lineage and the simultaneous deviation away from the muscle lineage. Mechanistically, EBF2 interacts with transcriptional co-activators CREB binding protein/ E1A-binding protein p300 (CBP/P300) to induce H3K27ac deposition and chromatin activation at BAT-associated genes to promote brown adipogenesis. Both mouse and pig EBF2 could potently stimulate adipogenesis in unspecified multipotent mesodermal stem cells. However, in pigs, EBF2 expression was depleted during the critical lineage specification time window, thus preventing the embryonic formation and development of porcine BAT. Hence, the elevation of EBF2 in mice, but not in pigs, promote chromatin activation to drive the progressive specification of brown fat lineage.

Identification and validation of up-regulated TNFAIP6 in osteoarthritis with type 2 diabetes mellitus

Lines of evidence have indicated that type 2 diabetes mellitus (T2DM) is an independent risk factor for osteoarthritis (OA) progression. However, the study focused on the relationship between T2DM and OA at the transcriptional level remains empty. We downloaded OA- and T2DM-related bulk RNA-sequencing and single-cell RNA sequencing data from the Gene Expression Omnibus (GEO) dataset. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were performed to screen out hub genes between OA and T2DM, and functional enrichment was done. Single-cell sequencing analysis was further used to screen key genes on OA and T2DM datasets. Rat chondrocytes and human articular cartilage were used to validate biomarkers among OA and T2DM. Sixty-eight hub genes were obtained, which were mainly enriched in the inflammatory response. We found that the hub gene TNFAIP6 is not only closely related to OA and T2DM but also a marker of prehypertrophic chondrocytes, which are closely related to the progression of OA. TNFAIP6 was found to be significantly elevated in CD14 + monocytes in T2DM patients, and this group of cells can promote inflammation. Validation on rat chondrocytes and human cartilage showed that TNFAIP6 was highly expressed in OA and further increased in the presence of T2DM or high glucose. Our study identified several characteristic modules and hub genes in the pathogenesis of T2DM-induced OA, which may facilitate further investigation of its molecular mechanisms. Up-regulated TNFAIP6 may contribute to OA in patients with T2DM by the recruitment of pro-inflammatory CD14 + monocytes in the OA synovium, which provides a potential target for the diagnosis and treatment of T2DM-associated OA.

Advancements in the Application of scRNA-Seq in Breast Research: A Review

Single-cell sequencing technology provides apparent advantages in cell population heterogeneity, allowing individuals to better comprehend tissues and organs. Sequencing technology is currently moving beyond the standard transcriptome to the single-cell level, which is likely to bring new insights into the function of breast cells. In this study, we examine the primary cell types involved in breast development, as well as achievements in the study of scRNA-seq in the microenvironment, stressing the finding of novel cell subsets using single-cell approaches and analyzing the problems and solutions to scRNA-seq. Furthermore, we are excited about the field's promising future.