Wound healing, fibroblast heterogeneity, and fibrosis

Porous gradient hydrogel promotes skin regeneration by angiogenesis

The skin has a multilayered structure, and deep-seated injuries are exposed to external microbial invasion and in vivo microenvironmental destabilization. Here, a bilayer bionic skin scaffold (Bilayer SF) was developed based on methacrylated sericin protein to mimic the skin's multilayered structure and corresponding functions. The outer layer (SF@TA), which mimics the epidermal layer, was endowed with the function of resisting external bacterial and microbial invasion using a small pore structure and bio-crosslinking with tannic acid (TA). The inner layer (SF@DA@Gel), which mimics the dermal layer, was used to promote cellular growth using a large pore structure and introducing dopamine (DA) to regulate the wound microenvironment. This Bilayer SF showed good mechanical properties and structural stability, satisfactory antioxidant and promote cell proliferation and migration abilities. In vitro studies confirmed the antimicrobial properties of the outer layer and the pro-angiogenic ability of the inner layer. In vivo animal studies demonstrated that the bilayer scaffolds promoted collagen deposition, neovascularization, and marginal hair follicle formation, which might be a promising new bionic skin scaffold.

Advances and applications of biomimetic biomaterials for endogenous skin regeneration

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

Netrin-1 co-cross-linked hydrogel accelerates diabetic wound healing in situ by modulating macrophage heterogeneity and promoting angiogenesis

Diabetic wounds, characterized by prolonged inflammation and impaired vascularization, are a serious complication of diabetes. This study aimed to design a gelatin methacrylate (GelMA) hydrogel for the sustained release of netrin-1 and evaluate its potential as a scaffold to promote diabetic wound healing. The results showed that netrin-1 was highly expressed during the inflammation and proliferation phases of normal wounds, whereas it synchronously exhibited aberrantly low expression in diabetic wounds. Neutralization of netrin-1 inhibited normal wound healing, and the topical application of netrin-1 accelerated diabetic wound healing. Mechanistic studies demonstrated that netrin-1 regulated macrophage heterogeneity via the A2bR/STAT/PPARγ signaling pathway and promoted the function of endothelial cells, thus accelerating diabetic wound healing. These data suggest that netrin-1 is a potential therapeutic target for diabetic wounds.

The role of extracellular matrix in angiogenesis: Beyond adhesion and structure

While the extracellular matrix (ECM) has long been recognized for its structural contributions, anchoring cells for adhesion, providing mechanical support, and maintaining tissue integrity, recent efforts have elucidated its dynamic, reciprocal, and diverse properties on angiogenesis. The ECM modulates angiogenic signaling and mechanical transduction, influences the extent and degree of receptor activation, controls cellular behaviors, and serves as a reservoir for bioactive macromolecules. Collectively, these factors guide the formation, maturation, and stabilization of a functional vascular network. This review aims to shed light on the versatile roles of the ECM in angiogenesis, transcending its traditional functions as a mere structural material. We will explore its engagement and synergy in signaling modulation, interactions with various angiogenic factors, and highlight its importance in both health and disease. By capturing the essence of the ECM's diverse functionalities, we highlight the significance in the broader context of vascular biology, enabling the design of novel biomaterials to engineer vascularized tissues and their potential therapeutic implications.

Multifunctional nanofibrous scaffolds for enhancing full-thickness wound healing loaded with Bletilla striata polysaccharides

The considerable challenge of wound healing remains. In this study, we fabricated a novel multifunctional core-shell nanofibrous scaffold named EGF@BSP-CeO2/PLGA (EBCP), which is composed of Bletilla striata polysaccharide (BSP), Ceria nanozyme (CeO2) and epidermal growth factor (EGF) as the core and poly(lactic-co-glycolic acid) (PLGA) as the shell via an emulsion electrospinning technique. An increase in the BSP content within the scaffolds corresponded to improved wound healing performance. These scaffolds exhibited increased hydrophilicity and porosity and improved mechanical properties and anti-UV properties. EBCP exhibited sustained release, and the degradation rate was <4 % in PBS for 30 days. The superior biocompatibility was confirmed by the MTT assay, hemolysis, and H&E staining. In addition, the in vitro results revealed that, compared with the other groups, the EBCP group presented excellent antioxidant and antibacterial effects. More importantly, the in vivo results indicated that the wound closure rate of the EBCP group reached 94.0 % on day 10 in the presence of H2O2. The results demonstrated that EBCP could comprehensively regulate the wound microenvironment, possess hemostatic abilities, and significantly promote wound healing. In conclusion, the EBCP is promising for facilitating the treatment of infected wounds and represents a potential material for clinical applications.

Piezo ion channels: long-sought-after mechanosensors mediating hypertension and hypertensive nephropathy

Recent advances in mechanobiology and the discovery of mechanosensitive ion channels have opened a new era of research on hypertension and related diseases. Piezo1 and Piezo2, first reported in 2010, are regarded as bona fide mechanochannels that mediate various biological and pathophysiological phenomena in multiple tissues and organs. For example, Piezo channels have pivotal roles in blood pressure control, triggering shear stress-induced nitric oxide synthesis and vasodilation, regulating baroreflex in the carotid sinus and aorta, and releasing renin from renal juxtaglomerular cells. Herein, we provide an overview of recent literature on the roles of Piezo channels in the pathogenesis of hypertension and related kidney damage, including our experimental data on the involvement of Piezo1 in podocyte injury and that of Piezo2 in renin expression and renal fibrosis in animal models of hypertensive nephropathy. The mechanosensitive ion channels Piezo1 and Piezo2 play various roles in the pathogenesis of systemic hypertension by acting on vascular endothelial cells, baroreceptors in the carotid artery and aorta, and the juxtaglomerular apparatus. Piezo channels also contribute to hypertensive nephropathy by acting on mesangial cells, podocytes, and perivascular mesenchymal cells.

Lineage mapping of extracellular vesicles: What cells do they come from and where do they go?

SIGNIFICANCE

Release of extracellular vesicles (EVs) by various cell types has been shown to mediate the delivery of biologically active payloads from donor cells to recipient cells, however, it remains unclear what cell types these EVs come from. With a focus on fluorescent reporters to monitor the release of EVs, especially those under the control of cell type specific promoters, we address the translational relevance of genetic tools in cultured cells, normal tissues and in models of development, injury, cancer and wound healing.

RECENT ADVANCES

It is well established that EVs are released by many cell types in the body via fusion and release processes at the plasma membrane. Since there remains debate about what fraction of EVs are released through regulated endosomal trafficking pathways vs. non-specific mechanisms the development and validation of novel molecular tools are important to address the cellular source of EVs.

CRITICAL ISSUES

There is a need to develop and characterize new cell type-specific reporter mouse models that build upon the examples detailed here to identify the cellular source of EVs with genetic approaches being useful in addressing these critical limitations.

FUTURE DIRECTIONS

Advances in reporter systems will drive a better understanding of EV subsets to identify compartment specific EV localization to guide the development of more translationally relevant models for the wound healing field.

Comprehensive transcription factor perturbations recapitulate fibroblast transcriptional states

Cell atlas projects have nominated recurrent transcriptional states as drivers of biological processes and disease, but their origins, regulation, and properties remain unclear. To enable complementary functional studies, we developed a scalable approach for recapitulating cell states in vitro using CRISPR activation (CRISPRa) Perturb-seq. Aided by a novel multiplexing method, we activated 1,836 transcription factors in two cell types. Measuring 21,958 perturbations showed that CRISPRa activated targets within physiological ranges, that epigenetic features predicted activatable genes, and that the protospacer seed region drove an off-target effect. Perturbations recapitulated in vivo fibroblast states, including universal and inflammatory states, and identified KLF4 and KLF5 as key regulators of the universal state. Inducing the universal state suppressed disease-associated states, highlighting its therapeutic potential. Our findings cement CRISPRa as a tool for perturbing differentiated cells and indicate that in vivo states can be elicited via perturbation, enabling studies of clinically relevant states ex vivo.

Electrospinning/3D printing drug-loaded antibacterial polycaprolactone nanofiber/sodium alginate-gelatin hydrogel bilayer scaffold for skin wound repair

Skin injuries and defects, as a common clinical issue, still cannot be perfectly repaired at present, particularly large-scale and infected skin defects. Therefore, in this work, a drug-loaded bilayer skin scaffold was developed for repairing full-thickness skin defects. Briefly, amoxicillin (AMX) was loaded on polycaprolactone (PCL) nanofiber via electrospinning to form the antibacterial nanofiber membrane (PCL-AMX) as the outer layer of scaffold to mimic epidermis. To maintain wound wettability and promote wound healing, external human epidermal growth factor (rhEGF) was loaded in sodium alginate-gelatin to form the hydrogel structure (SG-rhEGF) via 3D printing as inner layer of scaffold to mimic dermis. AMX and rhEGF were successfully loaded into the scaffold. The scaffold exhibited excellent physicochemical properties, with elongation at break and tensile modulus were 102.09 ± 6.74% and 206.83 ± 32.10 kPa, respectively; the outer layer was hydrophobic (WCA was 112.09 ± 4.67°), while the inner layer was hydrophilic (WCA was 48.87 ± 5.52°). Meanwhile, the scaffold showed excellent drug release and antibacterial characteristics. In vitro and in vivo studies indicated that the fabricated scaffold could enhance cell adhesion and proliferation, and promote skin wound healing, with favorable biocompatibility and great potential for skin regeneration and clinical application.

Cellular and molecular mechanisms of skin wound healing

Wound healing is a complex process that involves the coordinated actions of many different tissues and cell lineages. It requires tight orchestration of cell migration, proliferation, matrix deposition and remodelling, alongside inflammation and angiogenesis. Whereas small skin wounds heal in days, larger injuries resulting from trauma, acute illness or major surgery can take several weeks to heal, generally leaving behind a fibrotic scar that can impact tissue function. Development of therapeutics to prevent scarring and successfully repair chronic wounds requires a fuller knowledge of the cellular and molecular mechanisms driving wound healing. In this Review, we discuss the current understanding of the different phases of wound healing, from clot formation through re-epithelialization, angiogenesis and subsequent scar deposition. We highlight the contribution of different cell types to skin repair, with emphasis on how both innate and adaptive immune cells in the wound inflammatory response influence classically studied wound cell lineages, including keratinocytes, fibroblasts and endothelial cells, but also some of the less-studied cell lineages such as adipocytes, melanocytes and cutaneous nerves. Finally, we discuss newer approaches and research directions that have the potential to further our understanding of the mechanisms underpinning tissue repair.

Unveiling therapeutic potential: Adipose tissue-derived mesenchymal stem cells and their exosomes in the management of diabetes mellitus, wound healing, and chronic ulcers

Diabetes mellitus (DM) is a pervasive global health issue with substantial morbidity and mortality, often resulting in secondary complications, including diabetic wounds (DWs). These wounds, arising from hyperglycemia, diabetic neuropathy, anemia, and ischemia, afflict approximately 15% of diabetic patients, with a considerable 25% at risk of lower limb amputations. The conventional approaches for chronic and diabetic wounds management involves utilizing various therapeutic substances and techniques, encompassing growth factors, skin substitutes and wound dressings. In parallel, emerging cell therapy approaches, notably involving adipose tissue-derived mesenchymal stem cells (ADMSCs), have demonstrated significant promise in addressing diabetes mellitus and its complications. ADMSCs play a pivotal role in wound repair, and their derived exosomes have garnered attention for their therapeutic potential. This review aimed to unravel the potential mechanisms and provide an updated overview of the role of ADMSCs and their exosomes in diabetes mellitus and its associated complications, with a specific focus on wound healing.

Organ dependency on fascia connective tissue

Fascia is a specialized connective tissue system that encapsulates and interconnects between tissues and organs throughout the body. The fascia system regulates pain sensation, organ inflammation, trauma, and fibrotic diseases. This mini-review summarizes recent findings from animal models, which reveal the inter-dependency between tissues/organs and the fascia system. Special mechanisms are explored of fascia response to skin inflammatory processes and fibrotic microenvironments in trauma models. We highlight the functionally diverse communities of its fascia-born fibroblasts and the significance of their stage-specific differentiation and communication to disease progression. Understanding the molecular mechanisms and cellular processes within the fascia microenvironment may serve as a basis for future clinical translation.

A bitter flavonoid gum from Dorema aucheri accelerate wound healing in rats: Involvement of Bax/HSP 70 and hydroxyprolin mechanisms

BACKGROUND

Dorema aucheri gum (DAG) is a bitter flavonoid gum widely used for numerous medicinal purposes including wound recovery. The present work investigates the acute toxicity and wound-healing effects of DAG in excisional skin injury in rats.

MATERIALS AND METHODS

Sprague Dawley rats (24) were clustered into four groups, each rat had a full-thickness excisional dorsal neck injury (2.00 cm) and addressed with 0.2 mL of the following treatments for 15 days: Group A (vehicle), rats addressed with normal saline; Group B, rats received intrasite gel; C and D, rats addressed with 250 and 500 mg/kg of DAG, respectively.

RESULTS

The results revealed the absence of any toxic signs in rats who received oral dosages of 2 and 5 g/kg of DAG. Wound healing was significantly accelerated following DAG treatments indicated by smaller open areas and higher wound contraction percentages compared to vehicle rats. Histological evaluation revealed higher fibroblast formation, collagen deposition, and noticeably lower inflammatory cell infiltration in granulated skin tissues of DAG-addressed rats compared to vehicle rats. DAG treatment caused significant modulation of immunohistochemical proteins (decreased Bax and increased HSP 70) and inflammatory mediators (reduced TNF-α, IL-6, and magnified IL-10), which were significantly varied compared to vehicle rats. Moreover, topical DAG treatment led to significant upregulation of the hydroxyproline (HDX) (collagen) and antioxidant content. At the same time, decreased the lipid peroxidation (MDA) levels in healed tissues obtained from DAG-treated rats.

CONCLUSION

The present wound contraction by DAG might be linked with the modulatory effect of its phytochemicals (polysaccharides, flavonoids, and phenolic) on the cellular mechanisms, which justify their folkloric use and provokes further investigation as therapeutic drug additives for wound contraction.

Fibroblast and myofibroblast activation in normal tissue repair and fibrosis

The term 'fibroblast' often serves as a catch-all for a diverse array of mesenchymal cells, including perivascular cells, stromal progenitor cells and bona fide fibroblasts. Although phenotypically similar, these subpopulations are functionally distinct, maintaining tissue integrity and serving as local progenitor reservoirs. In response to tissue injury, these cells undergo a dynamic fibroblast-myofibroblast transition, marked by extracellular matrix secretion and contraction of actomyosin-based stress fibres. Importantly, whereas transient activation into myofibroblasts aids in tissue repair, persistent activation triggers pathological fibrosis. In this Review, we discuss the roles of mechanical cues, such as tissue stiffness and strain, alongside cell signalling pathways and extracellular matrix ligands in modulating myofibroblast activation and survival. We also highlight the role of epigenetic modifications and myofibroblast memory in physiological and pathological processes. Finally, we discuss potential strategies for therapeutically interfering with these factors and the associated signal transduction pathways to improve the outcome of dysregulated healing.

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.

Mechanical state transitions in the regulation of tissue form and function

From embryonic development, postnatal growth and adult homeostasis to reparative and disease states, cells and tissues undergo constant changes in genome activity, cell fate, proliferation, movement, metabolism and growth. Importantly, these biological state transitions are coupled to changes in the mechanical and material properties of cells and tissues, termed mechanical state transitions. These mechanical states share features with physical states of matter, liquids and solids. Tissues can switch between mechanical states by changing behavioural dynamics or connectivity between cells. Conversely, these changes in tissue mechanical properties are known to control cell and tissue function, most importantly the ability of cells to move or tissues to deform. Thus, tissue mechanical state transitions are implicated in transmitting information across biological length and time scales, especially during processes of early development, wound healing and diseases such as cancer. This Review will focus on the biological basis of tissue-scale mechanical state transitions, how they emerge from molecular and cellular interactions, and their roles in organismal development, homeostasis, regeneration and disease.

Neutrophil Extracellular Traps-Inhibiting and Fouling-Resistant Polysulfoxides Potently Prevent Postoperative Adhesion, Tumor Recurrence, and Metastasis

Peritoneal metastasis (PM) is considered one of the most dreaded forms of cancer metastases for both patients and physicians. Aggressive cytoreductive surgery (CRS) is the primary treatment for peritoneal metastasis. Unfortunately, this intensive treatment frequently causes clinical complications, such as postoperative recurrence, metastasis, and adhesion formation. Emerging evidence suggests that neutrophil extracellular traps (NETs) released by inflammatory neutrophils contribute to these complications. Effective NET-targeting strategies thus show considerable potential in counteracting these complications but remain challenging. Here, one type of sulfoxide-containing homopolymer, PMeSEA, with potent fouling-resistant and NET-inhibiting capabilities, is synthesized and screened. Hydrating sulfoxide groups endow PMeSEA with superior nonfouling ability, significantly inhibiting protein/cell adhesion. Besides, the polysulfoxides can be selectively oxidized by ClO- which is required to stabilize the NETs rather than H2O2, and ClO- scavenging effectively inhibits NETs formation without disturbing redox homeostasis in tumor cells and quiescent neutrophils. As a result, PMeSEA potently prevents postoperative adhesions, significantly suppresses peritoneal metastasis, and shows synergetic antitumor activity with chemotherapeutic 5-Fluorouracil. Moreover, coupling CRS with PMeSEA potently inhibits CRS-induced tumor metastatic relapse and postoperative adhesions. Notably, PMeSEA exhibits low in vivo acute and subacute toxicities, implying significant potential for clinical postoperative adjuvant treatment.

How to Keep Myofibroblasts under Control: Culture of Mouse Skin Fibroblasts on Soft Substrates

During the physiological healing of skin wounds, fibroblasts recruited from the uninjured adjacent dermis and deeper subcutaneous fascia layers are transiently activated into myofibroblasts to first secrete and then contract collagen-rich extracellular matrix into a mechanically resistant scar. Scar tissue restores skin integrity after damage but comes at the expense of poor esthetics and loss of tissue function. Stiff scar matrix also mechanically activates various precursor cells into myofibroblasts in a positive feedback loop. Persistent myofibroblast activation results in pathologic accumulation of fibrous collagen and hypertrophic scarring, called fibrosis. Consequently, the mechanisms of fibroblast-to-myofibroblast activation and persistence are studied to develop antifibrotic and prohealing treatments. Mechanistic understanding often starts in a plastic cell culture dish. This can be problematic because contact of fibroblasts with tissue culture plastic or glass surfaces invariably generates myofibroblast phenotypes in standard culture. We describe a straight-forward method to produce soft cell culture surfaces for fibroblast isolation and continued culture and highlight key advantages and limitations of the approach. Adding a layer of elastic silicone polymer tunable to the softness of normal skin and the stiffness of pathologic scars allows to control mechanical fibroblast activation while preserving the simplicity of conventional 2-dimensional cell culture.

Mechanism and application of fibrous proteins in diabetic wound healing: a literature review

Diabetic wounds are more complex than normal chronic wounds because of factors such as hypoxia, reduced local angiogenesis, and prolonged inflammation phase. Fibrous proteins, including collagen, fibrin, laminin, fibronectin, elastin etc., possess excellent inherent properties that make them highly advantageous in the area of wound healing. Accumulating evidence suggests that they contribute to the healing process of diabetic wounds by facilitating the repair and remodel of extracellular matrix, stimulating the development of vascular and granulation tissue, and so on. However, there is currently a lack of a comprehensive review of the application of these proteins in diabetes wounds. An overview of fibrous protein characteristics and the alterations linked to diabetic wounds is given in this article's initial section. Next is a summary of the advanced applications of fibrous proteins in the last five years, including acellular dermal matrix, hydrogel, foam, scaffold, and electrospun nanofibrous membrane. These dressings have the ability to actively promote healing in addition to just covering wounds compared to traditional wound dressings like gauze or bandage. Research on fibrous proteins and their role in diabetic wound healing may result in novel therapeutic modalities that lower the incidence of diabetic wounds and thereby enhance the health of diabetic patients.

Extracellular matrix hydrogels with fibroblast growth factor 2 containing exosomes for reconstructing skin microstructures

Decellularized extracellular matrix hydrogel (ECM hydrogel), a natural material derived from normal tissue with unique biocompatibility properties, is widely used for tissue repair. However, there are still problems such as poor biological activity and insufficient antimicrobial property. To overcome these drawbacks, fibroblast growth factor 2 (FGF 2) containing exosome (exoFGF 2) was prepared to increase the biological activity. Furthermore, the antimicrobial capacity of ECM hydrogel was optimised by using copper ions as a ligand-bonded cross-linking agent. The decellularized extracellular matrix hydrogel, intricately cross-linked with copper ions through ligand bonds and loaded with FGF 2 containing exosome (exoFGF 2@ECM/Cu2+ hydrogel), has demonstrated exceptional biocompatibility and antimicrobial properties. In vitro, exoFGF 2@ECM/Cu2+ hydrogel effectively promoted cell proliferation, migration, antioxidant and inhibited bacterial growth. In vivo, the wound area of rat treated with exoFGF 2@ECM/Cu2+ hydrogels were significantly smaller than that of other groups at Day 5 (45.24% ± 3.15%), Day 10 (92.20% ± 2.31%) and Day 15 (95.22% ± 1.28%). Histological examination showed that exoFGF 2@ECM/Cu2+ hydrogels promoted angiogenesis and collagen deposition. Overall, this hydrogel has the potential to inhibit bacterial growth and effectively promote wound healing in a variety of clinical applications.

Salvianolic acid B enhances tissue repair and regeneration by regulating immune cell migration and Caveolin-1-mediated blastema formation in zebrafish

INTRODUCTION

Non-healing wounds resulting from trauma, surgery, and chronic diseases annually affect millions of individuals globally, with limited therapeutic strategies available due to the incomplete understanding of the molecular processes governing tissue repair and regeneration. Salvianolic acid B (Sal B) has shown promising bioactivities in promoting angiogenesis and inhibiting inflammation. However, its regulatory mechanisms in tissue regeneration remain unclear.

PURPOSE

This study aims to investigate the effects of Sal B on wound healing and regeneration processes, along with its underlying molecular mechanisms, by employing zebrafish as a model organism.

METHODS

In this study, we employed a multifaceted approach to evaluate the impact of Sal B on zebrafish tail fin regeneration. We utilized whole-fish immunofluorescence, TUNEL staining, mitochondrial membrane potential (MMP), and Acridine Orange (AO) probes to analyze the tissue repair and regenerative under Sal B treatment. Additionally, we utilized transgenic zebrafish strains to investigate the migration of inflammatory cells during different phases of fin regeneration. To validate the importance of Caveolin-1 (Cav1) in tissue regeneration, we delved into its functional role using molecular docking and Morpholino-based gene knockdown techniques. Additionally, we quantified Cav1 expression levels through the application of in situ hybridization.

RESULTS

Our findings demonstrated that Sal B expedites zebrafish tail fin regeneration through a multifaceted mechanism involving the promotion of cell proliferation, suppression of apoptosis, and enhancement of MMP. Furthermore, Sal B was found to exert regulatory control over the dynamic aggregation and subsequent regression of immune cells during tissue regenerative processes. Importantly, we observed that the knockdown of Cav1 significantly compromised tissue regeneration, leading to an excessive infiltration of immune cells and increased levels of apoptosis. Moreover, the knockdown of Cav1 also affects blastema formation, a critical process influenced by Cav1 in tissue regeneration.

CONCLUSION

The results of this study showed that Sal B facilitated tissue repair and regeneration through regulating of immune cell migration and Cav1-mediated fibroblast activation, promoting blastema formation and development. This study highlighted the potential pharmacological effects of Sal B in promoting tissue regeneration. These findings contributed to the advancement of regenerative medicine research and the development of novel therapeutic approaches for trauma.

Nano-enzyme functionalized hydrogels promote diabetic wound healing through immune microenvironment modulation

Non-healing diabetic wounds often culminate in amputation and mortality. The main pathophysiological features in diabetic wounds involve the accumulation of M1-type macrophages and excessive oxidative stress. In this study, we engineered a nano-enzyme functionalized hydrogel by incorporating a magnesium ion-doped molybdenum-based polymetallic oxide (Mg-POM), a novel bioactive nano-enzyme, into a GelMA hydrogel, to obtain the GelMA@Mg-POM system to enhance diabetic wound healing. GelMA@Mg-POM was crosslinked using UV light, yielding a hydrogel with a uniformly porous three-dimensional mesh structure. In vitro experiments showed that GelMA@Mg-POM extraction significantly enhanced human umbilical vein endothelial cell (HUVEC) migration, scavenged ROS, improved the inflammatory microenvironment, induced macrophage reprogramming towards M2, and promoted HUVEC regeneration of CD31 and fibroblast regeneration of type I collagen. In in vivo experiments, diabetic rat wounds treated with GelMA@Mg-POM displayed enhanced granulation tissue genesis and collagen production, as evidenced by HE and Masson staining. Immunohistochemistry demonstrated the ability of GelMA@Mg-POM to mitigate macrophage-associated inflammatory responses and promote angiogenesis. Overall, these findings suggest that GelMA@Mg-POM holds significant promise as a biomaterial for treating diabetic wounds.

A bioactive xyloglucan polysaccharide hydrogel mechanically enhanced by Pluronic F127 micelles for promoting chronic wound healing

Chronic wounds represent a formidable global healthcare challenge due to the bacteria infections and uncontrollable inflammation responses, while developing wound healing materials capable of resolving these issues remains a challenge. In this study, we integrated xyloglucan (XG) with Pluronic F127 diacrylate (F127DA)to develop a composite hydrogel for wound healing, where the XG introduced anti-inflammation and anti-bacterial properties to the construct, and F127DA provides the photocurable properties essential for hydrogel formation and robust mechanical characteristics to achieve physical strength that matches tissue regeneration. The material characterizations suggested that XG/F127DA hydrogels had great biostability, blood compatibility and antibacterial effects, which was suitable to be used as a wound healing material. The in vitro analysis by culturing L929 fibroblasts on the hydrogel surface demonstrated that the inclusion of XG could promote the cellular proliferation rate, migration rate, and re-epithelialization-related marker expression, while downregulate the inflammation process. The XG/F127DA hydrogel was further used for the full-thickness skin wound healing test on mice, where the inclusion of XG significantly increased the wound closure rate through reducing the inflammation responses, and promote re-epithelialization and angiogenesis. These results indicated that XG/F127DA hydrogel has great potential to be used for wound healing in future clinical translation.

Exosomes derived from mouse vibrissa dermal papilla cells promote hair follicle regeneration during wound healing by activating Wnt/β-catenin signaling pathway

Hair follicle (HF) regeneration during wound healing continues to present a significant clinical challenge. Dermal papilla cell-derived exosomes (DPC-Exos) hold immense potential for inducing HF neogenesis. However, the accurate role and underlying mechanisms of DPC-Exos in HF regeneration in wound healing remain to be fully explained. This study, represents the first analysis into the effects of DPC-Exos on fibroblasts during wound healing. Our findings demonstrated that DPC-Exos could stimulate the proliferation and migration of fibroblasts, more importantly, enhance the hair-inducing capacity of fibroblasts. Fibroblasts treated with DPC-Exos were capable of inducing HF neogenesis in nude mice when combined with neonatal mice epidermal cells. In addition, DPC-Exos accelerated wound re-epithelialization and promoted HF regeneration during the healing process. Treatment with DPC-Exos led to increased expression levels of the Wnt pathway transcription factors β-catenin and Lef1 in both fibroblasts and the dermis of skin wounds. Specifically, the application of a Wnt pathway inhibitor reduced the effects of DPC-Exos on fibroblasts and wound healing. Accordingly, these results offer evidence that DPC-Exos promote HF regeneration during wound healing by enhancing the hair-inducing capacity of fibroblasts and activating the Wnt/β-catenin signaling pathway. This suggests that DPC-Exos may represent a promising therapeutic strategy for achieving regenerative wound healing.

Self-Assembly of Rhein and Matrine Nanoparticles for Enhanced Wound Healing

Carrier-free self-assembly has gradually shifted the focus of research on natural products, which effectively improve the bioavailability and the drug-loading rate. However, in spite of the existing studies, the development of self-assembled natural phytochemicals that possess pharmacological effects still has scope for further exploration and enhancement. Herein, a nano-delivery system was fabricated through the direct self-assembly of Rhein and Matrine and was identified as a self-assembled Rhein-Matrine nanoparticles (RM NPs). The morphology of RM NPs was characterized by TEM. The molecular mechanisms of self-assembly were explored using FT-IR, 1H NMR, and molecular dynamics simulation analysis. Gelatin methacryloyl (GelMA) hydrogel was used as a drug carrier for controlled release and targeted delivery of RM NPs. The potential wound repair properties of RM NPs were evaluated on a skin wound-healing model. TEM and dynamic light scattering study demonstrated that the RM NPs were close to spherical, and the average size was approximately 75 nm. 1H NMR of RM NPs demonstrated strong and weak changes in the interaction energies during self-assembly. Further molecular dynamics simulation analysis predicted the self-assembly behavior. An in vivo skin wound-healing model demonstrated that RM NPs present better protection effect against skin damages. Taken together, RM NPs are a new self-assembly system; this may provide new directions for natural product applications.

Electrical Stimulating Redox Membrane Incorporated with PVA/Gelatin Nanofiber for Diabetic Wound Healing

Chronic wounds adversely affect the quality of life. Although electrical stimulation has been utilized to treat chronic wounds, there are still limitations to practicing it due to the complicated power system. Herein, an electrostimulating membrane incorporated with electrospun nanofiber (M-sheet) to treat diabetic wounds is developed. Through the screen printing method, the various alternate patterns of both Zn and AgCl on a polyurethane substrate, generating redox-mediated electrical fields are introduced. The antibacterial ability of the patterned membrane against both E. coli and S. aureus is confirmed. Furthermore, the poly(vinyl alcohol) (PVA)/gelatin electrospun fiber is incorporated into the patterned membrane to enhance biocompatibility and maintain the wet condition in the wound environment. The M-sheet can improve cell proliferation and migration in vitro and has an immune regulatory effect by inducing the polarization of macrophage to the M2 phenotype. Finally, when applied to a diabetic skin wound model, the M-sheet displays an accelerated wound healing rate and enhances re-epithelialization, collagen synthesis, and angiogenesis. It suggests that the M-sheet is a simple and portable system for the spontaneous generation of electrical stimulation and has great potential to be used in the practical wound and other tissue engineering applications.

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

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

Exosomes: compositions, biogenesis, and mechanisms in diabetic wound healing

Diabetic wounds are characterized by incomplete healing and delayed healing, resulting in a considerable global health care burden. Exosomes are lipid bilayer structures secreted by nearly all cells and express characteristic conserved proteins and parent cell-associated proteins. Exosomes harbor a diverse range of biologically active macromolecules and small molecules that can act as messengers between different cells, triggering functional changes in recipient cells and thus endowing the ability to cure various diseases, including diabetic wounds. Exosomes accelerate diabetic wound healing by regulating cellular function, inhibiting oxidative stress damage, suppressing the inflammatory response, promoting vascular regeneration, accelerating epithelial regeneration, facilitating collagen remodeling, and reducing scarring. Exosomes from different tissues or cells potentially possess functions of varying levels and can promote wound healing. For example, mesenchymal stem cell-derived exosomes (MSC-exos) have favorable potential in the field of healing due to their superior stability, permeability, biocompatibility, and immunomodulatory properties. Exosomes, which are derived from skin cellular components, can modulate inflammation and promote the regeneration of key skin cells, which in turn promotes skin healing. Therefore, this review mainly emphasizes the roles and mechanisms of exosomes from different sources, represented by MSCs and skin sources, in improving diabetic wound healing. A deeper understanding of therapeutic exosomes will yield promising candidates and perspectives for diabetic wound healing management.

Chitosan-taurine nanoparticles cross-linked carboxymethyl chitosan hydrogels facilitate both acute and chronic diabetic wound healing

Wound dressing diligently facilitate healing by fostering hemostasis, immunoregulation, the angiogenesis, and collagen deposition. Our methodology entails fabricating chitosan-taurine nanoparticles (CS-Tau) through an ionic gelation method. The morphology of CS-Tau was observed utilizing Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Dynamic Light Scattering (DLS). The nanoparticles are subsequently incorporated into carboxymethyl chitosan hydrogels for crosslinking by EDC-NHS, yielding hydrogel dressings (CMCS-CS-Tau) designed to extend the duration of taurine release. In vitro investigations confirmed that these innovative compound dressings displayed superior biodegradation, biocompatibility, cytocompatibility, and non-toxicity, in addition to possessing anti-inflammatory properties, and stimulating the proliferation and mobility of human umbilical vein endothelial cells (HUVECs). Experiments conducted on mice models with full-thickness skin removal demonstrated that CMCS-CS-Tau efficaciously aided in wound healing by spurring angiogenesis, and encouraging collagen deposition. CMCS-CS-Tau can also minimize inflammation and promote collagen deposition in chronic diabetic wound. Hence, CMCS-CS-Tau promotes both acute and chronic diabetic wound healing. Furthermore, the sustained release mechanism of CMCS-CS-Tau on taurine reveals promising potential for extending its clinical utility in relation to various biological effects of taurine.

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

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

Fibroblast alignment and matrix remodeling induced by a stiffness gradient in a skin-derived extracellular matrix hydrogel

Large skin injuries heal as scars. Stiffness gradually increases from normal skin to scar tissue (20x higher), due to excessive deposition and crosslinking of extracellular matrix (ECM) mostly produced by (myo)fibroblasts. Using a custom mold, skin-derived ECM hydrogels (dECM) were UV crosslinked after diffusion of ruthenium (Ru) to produce a Ru-dECM gradient hydrogel. The Ru diffusion gradient equates to a stiffness gradient and models physiology of the scarred skin. Crosslinking in Ru-dECM hydrogels results in a 23-fold increase in stiffness from a stiffness similar to that of normal skin. Collagen fiber density increases in a stiffness-dependent fashion while stress relaxation also alters, with one additional Maxwell element necessary for characterizing Ru-dECM. Alignment of fibroblasts encapsulated in hydrogels suggests that the stiffness gradient directs fibroblasts to orientate at ∼45 ° in regions below 120 kPa. In areas above 120 kPa, fibroblasts decrease the stiffness prior to adjusting their orientation. Furthermore, fibroblasts remodel their surrounding ECM in a gradient-dependent fashion, with rearrangement of cell-surrounding ECM in high-stiffness areas, and formation of interlaced collagen bundles in low-stiffness areas. Overall, this study shows that fibroblasts remodel their local environment to generate an optimal ECM mechanical and topographical environment. STATEMENT OF SIGNIFICANCE: This study developed a versatile in vitro model with a gradient stiffness using skin-derived ECM hydrogel with unchanged biochemical environment. Using Ruthenium crosslinking, a 20-fold stiffness increase was achieved as observed in fibrotic skin. The interaction between fibroblasts and matrix depends on changes in the matrix stiffness. The stiffness gradient directed the alignment of fibroblasts with ∼45° in regions with≤ 120 kPa. The cells in regions with the higher stiffness decreased stiffness first and then oriented themselves. Furthermore, fibroblasts remodeled surrounding ECM and regulated its mechanics in a gradient-dependent fashion to reach an optimal condition. Our study highlights the dynamic interplay between cells and surrounding matrix, shedding light on potential mechanisms and strategies to target scar formation and remodeling.

The effects of Quercetin on wound healing in the human umbilical vein endothelial cells

An injury that affects the integrity of the skin, either inside or externally, is called a wound. Damaged tissue is repaired by a set of cellular and molecular mechanisms known as wound healing. Quercetin, a naturally occurring flavonoid, may hasten the healing of wounds. The study's objective was to investigate any potential impacts of quercetin on the wound-healing process. Human umbilical vein endothelial cells (HUVECs) were treated to varying dose ranges of quercetin (5-320 nM) for 24 and 48 h. Cultured cells were evaluated by using the MTT analysis, wound scratch assay and vascular tube formation. Furthermore the gene expression of VEGF and FGF were evaluated by qRT-PCR to determine the effects of quercetin on angiogenezis and wound repair. Positive effects of quercetin on cellular viability were demonstrated by the MTT experiment. In HUVECs quercetin promoted tube formation, migration, and proliferation while also averting wound breakage. Moreover, quercetin increased the expression of the FGF and VEGF genes, which aid in the healing of wounds in HUVECs. Quercetin may be bioactive molecule that successfully speeds up wound healing by regulating the vasculogenezis and healing cells.

UCHL1-dependent control of hypoxia-inducible factor transcriptional activity during liver fibrosis

Liver fibrosis is the excessive accumulation of extracellular matrix proteins that occurs in most types of chronic liver disease. At the cellular level, liver fibrosis is associated with the activation of hepatic stellate cells (HSCs) which transdifferentiate into a myofibroblast-like phenotype that is contractile, proliferative and profibrogenic. HSC transdifferentiation induces genome-wide changes in gene expression that enable the cell to adopt its profibrogenic functions. We have previously identified that the deubiquitinase ubiquitin C-terminal hydrolase 1 (UCHL1) is highly induced following HSC activation; however, the cellular targets of its deubiquitinating activity are poorly defined. Here, we describe a role for UCHL1 in regulating the levels and activity of hypoxia-inducible factor 1 (HIF1), an oxygen-sensitive transcription factor, during HSC activation and liver fibrosis. HIF1 is elevated during HSC activation and promotes the expression of profibrotic mediator HIF target genes. Increased HIF1α expression correlated with induction of UCHL1 mRNA and protein with HSC activation. Genetic deletion or chemical inhibition of UCHL1 impaired HIF activity through reduction of HIF1α levels. Furthermore, our mechanistic studies have shown that UCHL1 elevates HIF activity through specific cleavage of degradative ubiquitin chains, elevates levels of pro-fibrotic gene expression and increases proliferation rates. As we also show that UCHL1 inhibition blunts fibrogenesis in a pre-clinical 3D human liver slice model of fibrosis, these results demonstrate how small molecule inhibitors of DUBs can exert therapeutic effects through modulation of HIF transcription factors in liver disease. Furthermore, inhibition of HIF activity using UCHL1 inhibitors may represent a therapeutic opportunity with other HIF-related pathologies.

Single-cell transcriptional analysis of irradiated skin reveals changes in fibroblast subpopulations and variability in caveolin expression

BACKGROUND

Radiation-induced fibrosis (RIF) is an important late complication of radiation therapy, and the resulting damaging effects of RIF can significantly impact reconstructive outcomes. There is currently a paucity of effective treatment options available, likely due to the continuing knowledge gap surrounding the cellular mechanisms involved. In this study, detailed analyses of irradiated and non-irradiated human skin samples were performed incorporating histological and single-cell transcriptional analysis to identify novel features guiding development of skin fibrosis following radiation injury.

METHODS

Paired irradiated and contralateral non-irradiated skin samples were obtained from six female patients undergoing post-oncologic breast reconstruction. Skin samples underwent histological evaluation, immunohistochemistry, and biomechanical testing. Single-cell RNA sequencing was performed using the 10X single cell platform. Cells were separated into clusters using Seurat in R. The SingleR classifier was applied to ascribe cell type identities to each cluster. Differentially expressed genes characteristic to each cluster were then determined using non-parametric testing.

RESULTS

Comparing irradiated and non-irradiated skin, epidermal atrophy, dermal thickening, and evidence of thick, disorganized collagen deposition within the extracellular matrix of irradiated skin were readily appreciated on histology. These histologic features were associated with stiffness that was higher in irradiated skin. Single-cell RNA sequencing revealed six predominant cell types. Focusing on fibroblasts/stromal lineage cells, five distinct transcriptional clusters (Clusters 0-4) were identified. Interestingly, while all clusters were noted to express Cav1, Cluster 2 was the only one to also express Cav2. Immunohistochemistry demonstrated increased expression of Cav2 in irradiated skin, whereas Cav1 was more readily identified in non-irradiated skin, suggesting Cav1 and Cav2 may act antagonistically to modulate fibrotic cellular responses.

CONCLUSION

In response to radiation therapy, specific changes to fibroblast subpopulations and enhanced Cav2 expression may contribute to fibrosis. Altogether, this study introduces a novel pathway of caveolin involvement which may contribute to fibrotic development following radiation injury.

Integration mapping of cardiac fibroblast single-cell transcriptomes elucidates cellular principles of fibrosis in diverse pathologies

Single-cell technology has allowed researchers to probe tissue complexity and dynamics at unprecedented depth in health and disease. However, the generation of high-dimensionality single-cell atlases and virtual three-dimensional tissues requires integrated reference maps that harmonize disparate experimental designs, analytical pipelines, and taxonomies. Here, we present a comprehensive single-cell transcriptome integration map of cardiac fibrosis, which underpins pathophysiology in most cardiovascular diseases. Our findings reveal similarity between cardiac fibroblast (CF) identities and dynamics in ischemic versus pressure overload models of cardiomyopathy. We also describe timelines for commitment of activated CFs to proliferation and myofibrogenesis, profibrotic and antifibrotic polarization of myofibroblasts and matrifibrocytes, and CF conservation across mouse and human healthy and diseased hearts. These insights have the potential to inform knowledge-based therapies.

Blockade of Sialylation with Decrease in Polysialic Acid Levels Counteracts Transforming Growth Factor β1-Induced Skin Fibroblast-to-Myofibroblast Transition

Aberrant sialylation with overexpression of the homopolymeric glycan polysialic acid (polySia) was recently reported in fibroblasts from fibrotic skin lesions. Yet, whether such a rise in polySia levels or sialylation in general may be functionally implicated in profibrotic activation of fibroblasts and their transition to myofibroblasts remains unknown. Therefore, we herein explored whether inhibition of sialylation could interfere with the process of skin fibroblast-to-myofibroblast transition induced by the master profibrotic mediator transforming growth factor β1 (TGFβ1). Adult human skin fibroblasts were pretreated with the competitive pan-sialyltransferase inhibitor 3-Fax-peracetyl-Neu5Ac (3-Fax) before stimulation with recombinant human TGFβ1, and then analyzed for polySia expression, cell viability, proliferation, migratory ability, and acquisition of myofibroblast-like morphofunctional features. Skin fibroblast stimulation with TGFβ1 resulted in overexpression of polySia, which was effectively blunted by 3-Fax pre-administration. Pretreatment with 3-Fax efficiently lessened TGFβ1-induced skin fibroblast proliferation, migration, changes in cell morphology, and phenotypic and functional differentiation into myofibroblasts, as testified by a significant reduction in FAP, ACTA2, COL1A1, COL1A2, and FN1 gene expression, and α-smooth muscle actin, N-cadherin, COL1A1, and FN-EDA protein levels, as well as a reduced contractile capability. Moreover, skin fibroblasts pre-administered with 3-Fax displayed a significant decrease in Smad3-dependent canonical TGFβ1 signaling. Collectively, our in vitro findings demonstrate for the first time that aberrant sialylation with increased polySia levels has a functional role in skin fibroblast-to-myofibroblast transition and suggest that competitive sialyltransferase inhibition might offer new therapeutic opportunities against skin fibrosis.

Imaging at the nexus: how state of the art imaging techniques can enhance our understanding of cancer and fibrosis

Both cancer and fibrosis are diseases involving dysregulation of cell signaling pathways resulting in an altered cellular microenvironment which ultimately leads to progression of the condition. The two disease entities share common molecular pathophysiology and recent research has illuminated the how each promotes the other. Multiple imaging techniques have been developed to aid in the early and accurate diagnosis of each disease, and given the commonalities between the pathophysiology of the conditions, advances in imaging one disease have opened new avenues to study the other. Here, we detail the most up-to-date advances in imaging techniques for each disease and how they have crossed over to improve detection and monitoring of the other. We explore techniques in positron emission tomography (PET), magnetic resonance imaging (MRI), second generation harmonic Imaging (SGHI), ultrasound (US), radiomics, and artificial intelligence (AI). A new diagnostic imaging tool in PET/computed tomography (CT) is the use of radiolabeled fibroblast activation protein inhibitor (FAPI). SGHI uses high-frequency sound waves to penetrate deeper into the tissue, providing a more detailed view of the tumor microenvironment. Artificial intelligence with the aid of advanced deep learning (DL) algorithms has been highly effective in training computer systems to diagnose and classify neoplastic lesions in multiple organs. Ultimately, advancing imaging techniques in cancer and fibrosis can lead to significantly more timely and accurate diagnoses of both diseases resulting in better patient outcomes.

Electrospray Nano-Micro Composite Sodium Alginate Microspheres with Shape-Adaptive, Antibacterial, and Angiogenic Abilities for Infected Wound Healing

Nonhealing infectious wounds, characterized by bacterial colonization, wound microenvironment destruction, and shape complexity, present an intractable problem in clinical practice. Inspired by LEGOs, building-block toys that can be assembled into desired shapes, we proposed the use of electrospray nano-micro composite sodium alginate (SA) microspheres with antibacterial and angiogenic properties to fill irregularly shaped wounds instantly. Specifically, porous poly(lactic-co-glycolic acid) (PLGA) microspheres (MSs) encapsulating basic fibroblast growth factor (bFGF) were produced by a water-in-oil-in-water double-emulsion method. Then, bFGF@MSs were blended with the SA solution containing ZIF-8 nanoparticles. The resultant solution was electrosprayed to obtain nano-micro composite microspheres (bFGF@MS/ZIF-8@SAMSs). The composite MSs' size could be regulated by PLGA MS mass proportion and electrospray voltage. Moreover, bFGF, a potent angiogenic agent, and ZIF-8, bactericidal nanoparticles, were found to release from bFGF@MS/ZIF-8@SAMSs in a controlled and sustainable manner, which promoted cell proliferation, migration, and tube formation and killed bacteria. Through experimentation on rat models, bFGF@MS/ZIF-8@SAMSs were revealed to adapt to wound shapes and accelerate infected wound healing because of the synergistic effects of antibacterial and angiogenic abilities. In summation, this study developed a feasible approach to prepare bioactive nano-micro MSs as building blocks that can fill irregularly shaped infected wounds and improve healing.

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.

Metabolism and bioenergetics in the pathophysiology of organ fibrosis

Fibrosis is the tissue scarring characterized by excess deposition of extracellular matrix (ECM) proteins, mainly collagens. A fibrotic response can take place in any tissue of the body and is the result of an imbalanced reaction to inflammation and wound healing. Metabolism has emerged as a major driver of fibrotic diseases. While glycolytic shifts appear to be a key metabolic switch in activated stromal ECM-producing cells, several other cell types such as immune cells, whose functions are intricately connected to their metabolic characteristics, form a complex network of pro-fibrotic cellular crosstalk. This review purports to clarify shared and particular cellular responses and mechanisms across organs and etiologies. We discuss the impact of the cell-type specific metabolic reprogramming in fibrotic diseases in both experimental and human pathology settings, providing a rationale for new therapeutic interventions based on metabolism-targeted antifibrotic agents.

Integrating scRNA-seq and bulk RNA-seq to explore the differentiation mechanism of human nail stem cells mediated by onychofibroblasts

Introduction: Nail stem cell (NSC) differentiation plays a vital role in maintaining nail homeostasis and facilitating digit regeneration. Recently, onychofibroblasts (OFs), specialized mesenchymal cells beneath the nail matrix, have emerged as potential regulators of NSC differentiation. However, limited understanding of OFs' cellular properties and transcriptomic profiles hinders our comprehension of their role. This study aims to characterize human OFs and investigate their involvement in NSC differentiation. Methods: Human OFs were isolated and characterized for their mesenchymal stem cell (MSC)-like phenotype through flow cytometry and multilineage differentiation assays. Bulk RNA-seq analysis was conducted on three samples of OFs and control fibroblasts from human nail units to delineate their molecular features. Integrated analysis with scRNA-seq data was performed to identify key signaling pathways involved in OF-induced NSC differentiation. Co-culture experiments, siRNA transfection, RT-qPCR, and immunocytochemistry were employed to investigate the effect of OF-derived soluble proteins on NSC differentiation. Drug treatments, RT-qPCR, western blotting, and immunocytochemistry were used to verify the regulation of candidate signaling pathways on NSC differentiation in vitro. Results: Human OFs exhibited slow cell cycle kinetics, expressed typical MSC markers, and demonstrated multilineage differentiation potential. Bulk RNA-seq analysis revealed differential gene expression in OFs compared to control fibroblasts, highlighting their role in coordinating nail development. Integrated analysis identified BMP4 as a pivotal signal for OFs to participate in NSC differentiation through mesenchymal-epithelial interactions, with the TGF-beta pathway possibly mediating this signal. OFs synthesized and secreted more BMP4 than control fibroblasts, and BMP4 derived from OFs induced NSC differentiation in a co-culture model. Recombinant human BMP4 activated the TGF-beta pathway in NSCs, leading to cell differentiation, while the BMP type I receptor inhibitor LDN193189 attenuated this effect. Discussion: This study characterizes the cellular and molecular features of human OFs, demonstrating their ability to regulate NSC differentiation via the TGF-beta signaling pathway. These findings establish a connection between the dermal microenvironment and NSC differentiation, suggesting the potential of OFs, in conjunction with NSCs, for developing novel therapies targeting nail and digit defects, even severe limb amputation.

Development of a multifunctional nano-hydroxyapatite platform (nHEA) for advanced treatment of severely infected full-thickness skin wounds

The treatment of full-thickness skin injuries complicated by severe infection is hampered by the lack of comprehensive solutions that can regulate the various stages of wound healing. Consequently, there is an urgent need for a multifunctional dressing capable of multi-level regulation. In this study, we propose a novel solution by covalently integrating ε-poly-l-lysine-grafted gallic acid (EG) and in situ bioreduced silver nanoparticles (AgNPs) onto nano-hydroxyapatite (nHAP), thereby developing a multi-layered, multifunctional nanoplatform (nHEA). Cell experiments have shown that, compared to nHAP and nHAP loaded only with EG (nHEG), the addition of AgNPs to nHEA confers excellent antibacterial properties while maintaining optimal biocompatibility. The incorporation of EG onto nHEG and nHEA imparts antioxidation, anti-inflammatory, and pro-angiogenic functions, and the release of Ca2+ and EG further enhances fibroblast migration and collagen secretion. In a rat model of full-thickness skin injury with severe infection, nHEA demonstrates remarkable antibacterial and anti-inflammatory effects, along with promoting collagen remodeling and regeneration. Together, both cell experiments and animal studies confirm the significant potential of this innovative multifunctional nanoplatform in the treatment of full-thickness skin injuries with severe infection. STATEMENT OF SIGNIFICANCE: Treating infected full-thickness skin injuries poses a longstanding challenge due to the lack of comprehensive solutions that can regulate different stages of wound healing. This study introduces a novel multifunctional nanoplatform, nHEA, developed by covalently integrating ε-poly-l-lysine grafted with gallic acid (EG) and in situ bioreduced AgNPs onto nano-hydroxyapatite (nHAP). Cell experiments reveal that the integration of AgNPs enhances nHEA's antibacterial performance while maintaining optimal biocompatibility. The inclusion of EG bestows antioxidant, inflammation-regulating, and angiogenetic properties upon nHEA, and the release of Ca2+ and EG stimulates the migration and collagen secretion of fibroblast cells. Consequently, nHEA exhibits superior antibacterial and inflammation-regulating efficacy, and stimulates collagen remodeling and regeneration in vivo, making it a promising treatment for severely infected skin injuries.

A critical overview of challenging roles of medicinal plants in improvement of wound healing technology

PURPOSE

Chronic diseases often hinder the natural healing process, making wound infections a prevalent clinical concern. In severe cases, complications can arise, potentially leading to fatal outcomes. While allopathic treatments offer numerous options for wound repair and management, the enduring popularity of herbal medications may be attributed to their perceived minimal side effects. Hence, this review aims to investigate the potential of herbal remedies in efficiently treating wounds, presenting a promising alternative for consideration.

METHODS

A literature search was done including research, reviews, systematic literature review, meta-analysis, and clinical trials considered. Search engines such as Pubmed, Google Scholar, and Scopus were used while retrieving data. Keywords like Wound healing 'Wound healing and herbal combinations', 'Herbal wound dressing', Nanotechnology and Wound dressing were used.

RESULT

This review provides valuable insights into the role of natural products and technology-based formulations in the treatment of wound infections. It evaluates the use of herbal remedies as an effective approach. Various active principles from herbs, categorized as flavonoids, glycosides, saponins, and phenolic compounds, have shown effectiveness in promoting wound closure. A multitude of herbal remedies have demonstrated significant efficacy in wound management, offering an additional avenue for care. The review encompasses a total of 72 studies, involving 127 distinct herbs (excluding any common herbs shared between studies), primarily belonging to the families Asteraceae, Fabaceae, and Apiaceae. In research, rat models were predominantly utilized to assess wound healing activities. Furthermore, advancements in herbal-based formulations using nanotechnology-based wound dressing materials, such as nanofibers, nanoemulsions, nanofiber mats, polymeric fibers, and hydrogel-based microneedles, are underway. These innovations aim to enhance targeted drug delivery and expedite recovery. Several clinical-based experimental studies have already been documented, evaluating the efficacy of various natural products for wound care and management. This signifies a promising direction in the field of wound treatment.

CONCLUSION

In recent years, scientists have increasingly utilized evidence-based medicine and advanced scientific techniques to validate the efficacy of herbal medicines and delve into the underlying mechanisms of their actions. However, there remains a critical need for further research to thoroughly understand how isolated chemicals extracted from herbs contribute to the healing process of intricate wounds, which may have life-threatening consequences. This ongoing research endeavor holds great promise in not only advancing our understanding but also in the development of innovative formulations that expedite the recovery process.

Homeostasis and evolution in relation to regeneration and repair

Homeostasis constitutes a key concept in physiology and refers to self-regulating processes that maintain internal stability when adjusting to changing external conditions. It diminishes internal entropy constituting a driving force behind evolution. Natural selection might act on homeostatic regulatory mechanisms and control mechanisms including homeodynamics, allostasis, hormesis and homeorhesis, where different stable stationary states are reached. Regeneration is under homeostatic control through hormesis. Damage to tissues initiates a response to restore the impaired equilibrium caused by mild stress using cell proliferation, cell differentiation and cell death to recover structure and function. Repair is a homeorhetic change leading to a new stable stationary state with decreased functionality and fibrotic scarring without reconstruction of the 3-D pattern. Mechanisms determining entrance of the tissue or organ to regeneration or repair include the balance between innate and adaptive immune cells in relation to cell plasticity and stromal stem cell responses, and redox balance. The regenerative and reparative capacities vary in different species, distinct tissues and organs, and at different stages of development including ageing. Many cell signals and pathways play crucial roles determining regeneration or repair by regulating protein synthesis, cellular growth, inflammation, proliferation, autophagy, lysosomal function, metabolism and metalloproteinase cell signalling. Attempts to favour the entrance of damaged tissues to regeneration in those with low proliferative rates have been made; however, there are evolutionary constraint mechanisms leading to poor proliferation of stem cells in unfavourable environments or tumour development. More research is required to better understand the regulatory processes of these mechanisms.

IL-17 Control of Cutaneous Immune Homeostasis

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

Effect of pomegranate peel with/without autologous bone marrow on healing of acute cutaneous wounds in alloxan-induced diabetic rabbits

Background

Healing of bum wounds is commonly associated with many complications. Every year various new repair materials are developed and experimentally used for treating burn wounds. Humans with diabetes mellitus usually suffer from chronic wound healing. Vascular, neuropathic, immune function, and biochemical abnormalities each contribute to the altered tissue repair. One underlying factor that accompanies all diabetic ulcerations is poor vascular flow, a circumstance that impedes proper wound healing. Numerous studies have highlighted the importance of adequate vascular sufficiency and vessel proliferation in tissue repair and the lack thereof in diabetic wound healing. Other studies have looked at whether disarrayed capillary remodeling and maturation of vessels might play a role in impaired diabetic wound healing.

Aim

This investigation has been planned to report the influence of treatment with a mixture of both the powder of pomegranate peel (PP) accompanied with an autologous bone marrow (BM) on the cure of burn injuries in experimentally induced diabetic rabbits.

Methods

Alloxan monohydrate has been applied to create diabetes in 50 rabbits. Then in each rabbit, two deep second-degree burn wounds were experimentally created. The animals were then divided randomly into 5 treatment sections: non-treatment controls (C1), treated with an available commercial powder for wound (C2), treatment with powder of PP, treatment with alone BM, and the final group treated with PP powder with bone marrow (PPBM). The speed of wound closure and the histopathological changes during healing were measured. The levels of the biomarkers of rabbit platelet-derived growth factor AA (PDGF-AA) and rabbit protease-activated receptor 1 (PAR-1) were measured on days 0, 4, 8, and 12.

Results

Wound healing was markedly more rapid in all the treatment groups versus the control non-treated group. Interestingly, a rapid wound cure was significantly observed in the PPBM group versus the other treatment ones. The histological assessment clarified a significant elevation in the fibroblast and collagen scores in the PPBM group versus the other sections. In addition, there were significant increases in the serum levels of the biomarkers PDGF-AA and PAR-1 among groups.

Conclusion

Dependent on the results of current research, it can be concluded that both PP powder with BM PPBM significantly accelerate the healing process of burn wounds in experimentally induced diabetic rabbits.

Tissue fibroblasts are versatile immune regulators: An evaluation of their impact on the aging process

Fibroblasts are abundant stromal cells which not only control the integrity of extracellular matrix (ECM) but also act as immune regulators. It is known that the structural cells within tissues can establish an organ-specific immunity expressing many immune-related genes and closely interact with immune cells. In fact, fibroblasts can modify their immune properties to display both pro-inflammatory and immunosuppressive activities in a context-dependent manner. After acute insults, fibroblasts promote tissue inflammation although they concurrently recruit immunosuppressive cells to enhance the resolution of inflammation. In chronic pathological states, tissue fibroblasts, especially senescent fibroblasts, can display many pro-inflammatory and immunosuppressive properties and stimulate the activities of different immunosuppressive cells. In return, immunosuppressive cells, such as M2 macrophages and myeloid-derived suppressor cells (MDSC), evoke an excessive conversion of fibroblasts into myofibroblasts, thus aggravating the severity of tissue fibrosis. Single-cell transcriptome studies on fibroblasts isolated from aged tissues have confirmed that tissue fibroblasts express many genes coding for cytokines, chemokines, and complement factors, whereas they lose some fibrogenic properties. The versatile immune properties of fibroblasts and their close cooperation with immune cells indicate that tissue fibroblasts have a crucial role in the aging process and age-related diseases.

Targeting pathogenic fibroblast-like synoviocyte subsets in rheumatoid arthritis

Fibroblast-like synoviocytes (FLSs) play a central role in RA pathogenesis and are the main cellular component in the inflamed synovium of patients with rheumatoid arthritis (RA). FLSs are emerging as promising new therapeutic targets in RA. However, fibroblasts perform many essential functions that are required for sustaining tissue homeostasis. Direct targeting of general fibroblast markers on FLSs is challenging because fibroblasts in other tissues might be altered and side effects such as reduced wound healing or fibrosis can occur. To date, no FLS-specific targeted therapies have been applied in the clinical management of RA. With the help of high-throughput technologies such as scRNA-seq in recent years, several specific pathogenic FLS subsets in RA have been identified. Understanding the characteristics of these pathogenic FLS clusters and the mechanisms that drive their differentiation can provide new insights into the development of novel FLS-targeting strategies for RA. Here, we discuss the pathogenic FLS subsets in RA that have been elucidated in recent years and potential strategies for targeting pathogenic FLSs.

Synergistic Enhancement of Targeted Wound Healing by Near-Infrared Photodynamic Therapy and Silver Metal-Organic Frameworks Combined with S- or N-Doped Carbon Dots

The literature data emphasize that nanoparticles might improve the beneficial effects of near-infrared light (NIR) on wound healing. This study investigates the mechanisms of the synergistic wound healing potential of NIR light and silver metal-organic frameworks combined with nitrogen- and sulfur-doped carbon dots (AgMOFsN-CDs and AgMOFsS-CDs, respectively), which was conducted by testing the fibroblasts viability, scratch assays, biochemical analysis, and synchrotron-based Fourier transform infrared (SR-FTIR) cell spectroscopy and imaging. Our findings reveal that the combined treatment of AgMOFsN-CDs and NIR light significantly increases cell viability to nearly 150% and promotes cell proliferation, with reduced interleukin-1 levels, suggesting an anti-inflammatory response. SR-FTIR spectroscopy shows this combined treatment results in unique protein alterations, including increased α-helix structures and reduced cross-β. Additionally, protein synthesis was enhanced upon the combined treatment. The likely mechanism behind the observed changes is the charge-specific interaction of N-CDs from the AgMOFsN-CDs with proteins, enhanced by NIR light due to the nanocomposite's optical characteristics. Remarkably, the complete wound closure in the in vitro scratch assay was achieved exclusively with the combined NIR and AgMOFsN-CDs treatment, demonstrating the promising application of combined AgMOFsN-CDs with NIR light photodynamic therapy in regenerative nanomedicine and tissue engineering.

Multifunctional antibacterial hydrogels for chronic wound management

Chronic wounds have gradually evolved into a global health challenge, comprising long-term non-healing wounds, local tissue necrosis, and even amputation in severe cases. Accordingly, chronic wounds place a considerable psychological and economic burden on patients and society. Chronic wounds have multifaceted pathogenesis involving excessive inflammation, insufficient angiogenesis, and elevated reactive oxygen species levels, with bacterial infection playing a crucial role. Hydrogels, renowned for their excellent biocompatibility, moisture retention, swelling properties, and oxygen permeability, have emerged as promising wound repair dressings. However, hydrogels with singular functions fall short of addressing the complex requirements associated with chronic wound healing. Hence, current research emphasises the development of multifunctional antibacterial hydrogels. This article reviews chronic wound characteristics and the properties and classification of antibacterial hydrogels, as well as their potential application in chronic wound management.