Extracellular vesicles derived from fibroblasts promote wound healing by optimizing fibroblast and endothelial cellular functions

Immunomodulatory Hydrogel for Electrostatically Capturing Pro-inflammatory Factors and Chemically Scavenging Reactive Oxygen Species in Chronic Diabetic Wound Remodeling

Diabetic wound exhibits the complex characteristics involving continuous oxidative stress and excessive expression of pro-inflammatory cytokines to cause a long-term inflammatory microenvironment. The repair healing of chronic diabetic wounding is tremendously hindered due to persistent inflammatory reaction. To address the aforementioned issues, here, a dual-functional hydrogel is designed, consisting of N1-(4-boronobenzyl)-N3-(4-boronophenyl)-N1, N1, N3, N3-tetramethylpropane-1, 3-diaminium (TSPBA) modified polyvinyl alcohol (PVA) and methacrylamide carboxymethyl chitosan (CMCSMA) can not only electrostatically adsorb proinflammatory cytokines of IL1-β and TNF-α, but can also chemically scavenge the excessive reactive oxygen species (ROS) in situ. Both in vitro and in vivo evaluations verify that the negatively charged and ROS-responsive hydrogel (NCRH) can effectively modulate the chronic inflammatory microenvironment of diabetic wounds and significantly enhance wound remodeling. More importantly, the well-designed NCRH shows a superior skin recovery in comparison with the commercial competitor product of wound dressing. Consequently, the current work highlights the need for new strategies to expedite the healing process of diabetic wounds and offers a wound dressing material with immunomodulation.

Collagen-Based Nanoparticles as Drug Delivery System in Wound Healing Applications

Background

Conventional wound dressings often adhere to wounds and can cause secondary injury due to their lack of anti-inflammatory and antibacterial properties. In contrast, collagen-based nanoparticles (NPs) as drug delivery systems exhibit both biocompatibility and biodegradability, presenting a promising avenue for accelerating wound healing processes.

Aims of Study

This review aims to provide a comprehensive overview of the mechanisms involved in wound healing, description of the attributes of ideal wound dressings, understanding of wound healing efficacy of collagen, exploring NPs-mediated drug delivery mechanisms in wound therapy, detailing the synthesis and fabrication techniques of collagen-based NPs, and delineating the applications of various collagen-based NPs infused wound dressings on wound healing.

Methodology

This review synthesizes relevant literature from reputable databases such as Scopus, Science Direct, Google Scholar, and PubMed.

Results

A diverse array of collagen-based NPs, including nanopolymers, metal NPs, nanoemulsions, nanoliposomes, and nanofibers, demonstrate pronounced efficacy in promoting wound closure and tissue regeneration. The incorporation of collagen-based NPs has not only become an agent for the delivery of therapeutics but also actively contributes to the wound healing cascade.

Conclusion

In conclusion, In brief, the use of collagen-based NPs presents a compelling strategy for expediting wound healing processes.

GelMA loaded with exosomes from human minor salivary gland organoids enhances wound healing by inducing macrophage polarization

Non-healing skin wounds pose significant clinical challenges, with biologic products like exosomes showing promise for wound healing. Saliva and saliva-derived exosomes, known to accelerate wound repair, yet their extraction is difficult due to the complex environment of oral cavity. In this study, as a viable alternative, we established human minor salivary gland organoids (hMSG-ORG) to produce exosomes (MsOrg-Exo). In vitro, MsOrg-Exo significantly enhanced cell proliferation, migration, and angiogenesis. When incorporated into a GelMA-based controlled-release system, MsOrg-Exo demonstrated controlled release, effectively improving wound closure, collagen synthesis, angiogenesis, and cellular proliferation in a murine skin wound model. Further molecular analyses revealed that MsOrg-Exo promotes proliferation, angiogenesis and the secretion of growth factors in wound sites. Proteomic profiling showed that MsOrg-Exo's protein composition is similar to human saliva and enriched in proteins essential for wound repair, immune modulation, and coagulation. Additionally, MsOrg-Exo was found to modulate macrophage polarization, inducing a shift towards M1 and M2 phenotypes in vitro within 48 h and predominantly towards the M2 phenotype in vivo after 15 days. In conclusion, our study successfully extracted MsOrg-Exo from hMSG-ORGs, confirmed the effectiveness of the controlled-release system combining MsOrg-Exo with GelMA in promoting skin wound healing, and explored the potential role of macrophages in this action.

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.

Cell-Specific Impacts of Surface Coating Composition on Extracellular Vesicle Secretion

Biomaterial properties have recently been shown to modulate extracellular vesicle (EV) secretion and cargo; however, the effects of substrate composition on EV production remain underexplored. This study investigates the impacts of surface coatings composed of collagen I (COLI), fibronectin (FN), and poly l-lysine (PLL) on EV secretion for applications in therapeutic EV production and to further understanding of how changes in the extracellular matrix microenvironment affect EVs. EV secretion from primary bone marrow-derived mesenchymal stromal cells (BMSCs), primary adipose-derived stem cells (ASCs), HEK293 cells, NIH3T3 cells, and RAW264.7 cells was characterized on the different coatings. Expression of EV biogenesis genes and cellular adhesion genes was also analyzed. COLI coatings significantly decreased EV secretion in RAW264.7 cells, with associated decreases in cell viability and changes in EV biogenesis-related and cell adhesion genes at day 4. FN coatings increased EV secretion in NIH3T3 cells, while PLL coatings increased EV secretion in ASCs. Surface coatings had significant effects on the capacity of EVs derived from RAW264.7 and NIH3T3 cells to impact in vitro macrophage proliferation. Overall, surface coatings had different cell-specific effects on EV secretion and in vitro functional capacity, thus highlighting the potential of substrate coatings to further the development of clinical EV production systems.

Downregulated SPESP1-driven fibroblast senescence decreases wound healing in aged mice

BACKGROUND

Human dermal fibroblasts (HDFs) are essential in the processes of skin ageing and wound healing. However, the underlying mechanism of HDFs in skin healing of the elderly has not been well defined. This study aims to elucidate the mechanisms of HDFs senescence and how senescent HDFs affect wound healing in aged skin.

METHODS

The expression and function of sperm equatorial segment protein 1 (SPESP1) in skin ageing were evaluated via in vivo and in vitro experiments. To delve into the potential molecular mechanisms by which SPESP1 influences skin ageing, a combination of techniques was employed, including proteomics, RNA sequencing, immunoprecipitation, chromatin immunoprecipitation and liquid chromatography-mass spectrometry analyses. Clearance of senescent cells by dasatinib plus quercetin (D+Q) was investigated to explore the role of SPESP1-induced senescent HDFs in wound healing.

RESULTS

Here, we define the critical role of SPESP1 in ameliorating HDFs senescence and retarding the skin ageing process. Mechanistic studies demonstrate that SPESP1 directly binds to methyl-binding protein, leading to Decorin demethylation and subsequently upregulation of its expression. Moreover, SPESP1 knockdown delays wound healing in young mice and SPESP1 overexpression induces wound healing in old mice. Notably, pharmacogenetic clearance of senescent cells by D+Q improved wound healing in SPESP1 knockdown skin.

CONCLUSIONS

Taken together, these findings reveal the critical role of SPESP1 in skin ageing and wound healing, expecting to facilitate the development of anti-ageing strategies and improve wound healing in the elderly.

Insights into optimizing exosome therapies for acute skin wound healing and other tissue repair

Exosome therapy holds great promise as a novel approach to improve acute skin wound healing. This review provides a comprehensive overview of the current understanding of exosome biology and its potential applications in acute skin wound healing and beyond. Exosomes, small extracellular vesicles secreted by various stem cells, have emerged as potent mediators of intercellular communication and tissue repair. One advantage of exosome therapy is its ability to avoid potential risks associated with stem cell therapy, such as immune rejection or stem cells differentiating into unwanted cell types. However, further research is necessary to optimize exosome therapy, not only in the areas of exosome isolation, characterization, and engineering, but also in determining the optimal dose, timing, administration, and frequency of exosome therapy. Thus, optimization of exosome therapy is critical for the development of more effective and safer exosome-based therapies for acute skin wound healing and other diseases induced by cancer, ischemia, or inflammation. This review provides valuable insights into the potential of exosome therapy and highlights the need for further research to optimize exosome therapy for clinical use.

Hyperbaric oxygen therapy promotes the browning of white fat and contributes to the healing of diabetic wounds

Non-healing wounds are one of the chronic complications of diabetes and have remained a worldwide challenge as one of the major health problems. Hyperbaric oxygen (HBO) therapy is proven to be very successful for diabetic wound treatment, for which the molecular basis is not understood. Adipocytes regulate multiple aspects of repair and may be therapeutic for inflammatory diseases and defective wound healing associated with aging and diabetes. Endothelial cell-derived extracellular vesicles could promote wound healing in diabetes. To study the mechanism by which HBO promotes wound healing in diabetes, we investigated the effect of HBO on fat cells in diabetic mice. A diabetic wound mouse model was established and treated with HBO. Haematoxylin and eosin (H&E) staining and immunofluorescence were used for the analysis of wound healing. To further explore the mechanism, we performed whole-genome sequencing on extracellular vesicles (EVs). Furthermore, we conducted in vitro experiments. Specifically, exosomes were collected from human umbilical vein endothelial cell (HUVEC) cells after HBO treatment, and then these exosomes were co-incubated with adipose tissue. The wound healing rate in diabetic mice treated with HBO was significantly higher. HBO therapy promotes the proliferation of adipose precursor cells. HUVEC-derived exosomes treated with HBO significantly promoted fat cell browning. These data clarify that HBO therapy may promote vascular endothelial cell proliferation and migration, and promote browning of fat cells through vascular endothelial cells derived exosomes, thereby promoting diabetic wound healing. This provides new ideas for the application of HBO therapy in the treatment of diabetic trauma.

Cobalt/Bioglass Nanoparticles Enhanced Dermal Regeneration in a 3-Layered Electrospun Scaffold

Purpose

Due to the multilayered structure of the skin tissue, the architecture of its engineered scaffolds needs to be improved. In the present study, 45s5 bioglass nanoparticles were selected to induce fibroblast proliferation and their protein secretion, although cobalt ions were added to increase their potency.

Methods

A 3-layer scaffold was designed as polyurethane (PU) - polycaprolactone (PCL)/ collagen/nanoparticles-PCL/collagen. The scaffolds examined by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), tensile, surface hydrophilicity and weight loss. Biological tests were performed to assess cell survival, adhesion and the pattern of gene expression.

Results

The mechanical assay showed the highest young modulus for the scaffold with the doped nanoparticles and the water contact angle of this scaffold after chemical crosslinking of collagen was reduced to 52.34±7.7°. In both assessments, the values were statistically compared to other groups. The weight loss of the corresponding scaffold was the highest value of 82.35±4.3 % due to the alkaline effect of metal ions and indicated significant relations in contrast to the scaffold with non-doped particles and bare one (P value<0.05). Moreover, better cell expansion, greater cell confluence and a lower degree of toxicity were confirmed. The up-regulation of TGF β1 and VEGF genes introduced this scaffold as a better model for the fibroblasts commitment to a new skin tissue among bare and nondoped scaffold (P value<0.05).

Conclusion

The 3-layered scaffold which is loaded with cobalt ions-bonded bioglass nanoparticles, is a better substrate for the culture of the fibroblasts.

Anti-melanogenic effect of exosomes derived from human dermal fibroblasts (BJ-5ta-Ex) in C57BL/6 mice and B16F10 melanoma cells

Exosomes are involved in intercellular communication by transferring cargo between cells and altering the specific functions of the target cells. Recent studies have demonstrated the therapeutic effects of exosomes in several skin diseases. However, understanding of the effects of exosomes on anti-pigmentation is limited. Therefore, we investigated whether BJ-5ta exosomes (BJ-5ta-Ex) derived from human foreskin fibroblasts regulate melanogenesis and delineated the underlying mechanism. Interestingly, treatment with BJ-5ta-Ex induced decreased melanin content, tyrosinase (TYR) activity, and expression of melanogenesis-related genes, including microphthalmia-related transcription factor (MITF), TYR, tyrosinase-related protein-1 (TRP1), and tyrosinase-related protein-2 (TRP2). In addition, BJ-5ta-Ex downregulated the cAMP/PKA and GSK-3β/β-catenin signaling pathways and upregulated the MAPK/ERK signaling pathway. Notably, treatment with BJ-5ta-Ex inhibited α-melanocyte-stimulating hormone-induced melanosome transport and decreased the expression of key proteins involved in melanosome transport, namely, rab27a and melanophilin (MLPH). To further confirm the depigmenting effects of BJ-5ta-Ex, we conducted experiments using a three-dimensional reconstituted human full skin model and ultraviolet B (UVB)-irradiated mouse model. Treatment with BJ-5ta-Ex improved tissue brightness and reduced the distribution of melanosomes. In UVB-irradiated mouse ears, BJ-5ta-Ex reduced the number of active melanocytes and melanin granules. These results demonstrate that BJ-5ta-Ex can be useful for the clinical treatment of hyperpigmentation disorders.

Functionalised biomaterials as synthetic extracellular matrices to promote vascularisation and healing of diabetic wounds

Diabetic foot ulcers (DFU) are a type of chronic wound that constitute one of the most serious and debilitating complications associated with diabetes. The lack of clinically efficacious treatments to treat these recalcitrant wounds can lead to amputations for those worst affected. Biomaterial-based approaches offer great hope in this regard, as they provide a template for cell infiltration and tissue repair. However, there is an additional need to treat the underlying pathophysiology of DFUs, in particular insufficient vascularization of the wound which significantly hampers healing. Thus, the addition of pro-angiogenic moieties to biomaterials is a promising strategy to promote the healing of DFUs and other chronic wounds. In this review, we discuss the potential of biomaterials as treatments for DFU and the approaches that can be taken to functionalise these biomaterials such that they promote vascularisation and wound healing in pre-clinical models.

The diffusion of normal skin wound myofibroblast-derived microvesicles differs according to matrix composition

Microvesicles (MVs) are a subtype of extracellular vesicles that can transfer biological information over long distances, affecting normal and pathological processes including skin wound healing. However, the diffusion of MVs into tissues can be impeded by the extracellular matrix (ECM). We investigated the diffusion of dermal wound myofibroblast-derived MVs into the ECM by using hydrogels composed of different ECM molecules such as fibrin, type III collagen and type I collagen that are present during the healing process. Fluorescent MVs mixed with hydrogels were employed to detect MV diffusion using fluorometric methods. Our results showed that MVs specifically bound type I collagen and diffused freely out of fibrin and type III collagen. Further analysis using flow cytometry and specific inhibitors revealed that MVs bind to type I collagen via the α2β1 integrin. These data demonstrate that MV transport depends on the composition of the wound environment.

Research on evolution process of full-layer incision of skin tissue under different laser incidences

Considering difficulties of achieving vertical incidence of beam in different positions of skin, it is significant to study potential effects of incidence angles of laser on incisions. Surgical platform with a 1064 nm continuous fiber laser was established. Incident angle was adopted and real-time temperature fluctuations in laser operating area could be monitored. The rats were treated with laser at day 0 and day 3 after incision modeling, and H&E, Masson, Sirius Red, and Immuno-histochemical staining and enzyme-linked immunosorbent assay were adopted at day 3, 7, 14 to analyze the performance of healing. Laser with energy density of 67.54 J/mm2 can effectively accelerate wound healing in vivo, in which a laser with incident angle around 60° can effectively avoid scar hyperplasia. Therefore, the use of low energy laser with a small deflection angle has a good clinical application prospect in promoting wound healing.

ApoSEVs-Mediated Modulation of Versatile Target Cells Promotes Diabetic Wound Healing: Unveiling a Promising Strategy

Background

Diabetic chronic wounds present a formidable challenge in clinical management, lacking effective treatment options. Mesenchymal stem cell (MSC) transplantation has emerged as a promising therapy for tissue repair and regeneration. However, transplanted MSCs often undergo rapid apoptosis, giving rise to heterogeneous extracellular vesicles (EVs), including apoptotic bodies (apoBDs) and apoptotic small extracellular vesicles (apoSEVs). The potential stimulatory role of these EVs in diabetic wound healing remains unknown.

Methods

In this study, we investigated the effects of apoSEVs derived from adipose-derived mesenchymal/stromal cells (ADSCs) on the recovery of diabetic wounds by modulating the function of versatile target cells. First, we characterized the apoSEVs and apoBDs derived from apoptotic ADSCs. Subsequently, we evaluated the effects of apoSEVs and apoBDs on macrophages, endothelial cells, and fibroblasts, three essential cell types in wound healing, under high-glucose conditions. Furthermore, we developed a gelatin methacryloyl (GelMA) hydrogel for the sustained release of apoSEVs and investigated its therapeutic effects on wound healing in type 2 diabetic mice in vivo.

Results

apoSEVs facilitated the polarization of M1 phenotype macrophages to M2 phenotype, promoted proliferation, migration, and tube formation of endothelial cells, and enhanced fibroblast proliferation and migration. However, apoBDs failed to improve the function of endothelial cells and fibroblasts. In vivo, the apoSEVs-loaded GelMA effectively promoted wound healing by facilitating collagen fiber deposition, angiogenesis, and immune regulation.

Conclusion

Our study elucidates the beneficial effects of apoSEVs on wound recovery in diabetes and introduces a novel strategy for diabetic wound treatment based on apoSEVs.

Engineered extracellular vesicles from human skin cells induce pro-β-cell conversions in pancreatic ductal cells

Direct nuclear reprogramming has the potential to enable the development of β cell replacement therapies for diabetes that do not require the use of progenitor/stem cell populations. However, despite their promise, current approaches to β cell-directed reprogramming rely heavily on the use of viral vectors. Here we explored the use of extracellular vesicles (EVs) derived from human dermal fibroblasts (HDFs) as novel non-viral carriers of endocrine cell-patterning transcription factors, to transfect and transdifferentiate pancreatic ductal epithelial cells (PDCs) into hormone-expressing cells. Electrotransfection of HDFs with expression plasmids for Pdx1, Ngn3, and MafA (PNM) led to the release of EVs loaded with PNM at the gene, mRNA, and protein level. Exposing PDC cultures to PNM-loaded EVs led to successful transfection and increased PNM expression in PDCs, which ultimately resulted in endocrine cell-directed conversions based on the expression of insulin/c-peptide, glucagon, and glucose transporter 2 (Glut2). These findings were further corroborated in vivo in a mouse model following intraductal injection of PNM- vs sham-loaded EVs. Collectively these findings suggest that dermal fibroblast-derived EVs could potentially serve as a powerful platform technology for the development and deployment of non-viral reprogramming-based cell therapies for insulin-dependent diabetes.

Neonatal-Tissue-Derived Extracellular Vesicle Therapy (NEXT): A Potent Strategy for Precision Regenerative Medicine

Extracellular vesicle (EV)-based therapies have emerged as a promising means in regenerative medicine. However, the conventional EV therapy strategy displays some limitations, such as inefficient EV production and lack of tissue-specific repair effects. Here, it is reported that neonatal-tissue-derived EV therapy (NEXT) is a potent strategy for precision tissue repair. In brief, large amounts of EVs with higher yield/purity can be readily isolated from desired tissues with less production time/cost compared to the conventional cell-culture-based method. Moreover, source factors, such as age and tissue type, can affect the repair efficacy of such tissue-derived EVs in different tissue injury models (skin wounds and acute kidney injury), and neonatal-tissue-derived EVs show superior tissue repair potency compared with adult-tissue-derived EVs. Different age- or tissue-type-derived EVs have distinct composition (e.g., protein) signatures that are likely due to the diverse metabolic patterns of the donor tissues, which may contribute to the specific repair action modes of NEXT in different types of tissue injury. Furthermore, neonatal-tissue-derived EVs can be incorporated with bioactive materials for advanced tissue repair. This study highlights that the NEXT strategy may provide a new avenue for precision tissue repair in many types of tissue injury.

Engineering exosome-based biomimetic nanovehicles for wound healing

Complexity and difficulties in wound management are pressing concerns that affect patients' quality of life and may result in tissue infection, necrosis, and loss of local and systemic functions. Hence, novel approaches to accelerate wound healing are being actively explored over the last decade. Exosomes as important mediators of intercellular communications are promising natural nanocarriers due to their biocompatibility, low immunogenicity, drug loading and targeting capacities, and innate stability. More importantly, exosomes are developed as a versatile pharmaceutical engineering platform for wound repair. This review provides an overview of the biological and physiological functions of exosomes derived from a variety of biological origins during wound healing phases, strategies for exosomal engineering, and therapeutic applications in skin regeneration.

Extracellular vesicles from human plasma for biomarkers discovery: Impact of anticoagulants and isolation techniques

Extracellular vesicles (EVs) isolated from plasma are increasingly recognized as promising circulating biomarkers for disease discovery and progression, as well as for therapeutic drug delivery. The scientific community underlined the necessity of standard operative procedures for the isolation and storage of the EVs to ensure robust results. The understanding of the impact of the pre-analytical variables is still limited and some considerations about plasma anticoagulants and isolation methods are necessary. Therefore, we performed a comparison study between EVs isolated by ultracentrifugation and by affinity substrate separation from plasma EDTA and sodium citrate. The EVs were characterized by Nano Tracking Analysis, Western Blot, cytofluorimetric analysis of surface markers, and lipidomic analysis. While anticoagulants did not significantly alter any of the analyzed parameters, the isolation methods influenced EVs size, purity, surface markers expression and lipidomic profile. Compared to ultracentrifugation, affinity substrate separation yielded bigger particles highly enriched in tetraspanins (CD9, CD63, CD81), fatty acids and glycerolipids, with a predominant LDL- and vLDL-like contamination. Herein, we highlighted that the isolation method should be carefully evaluated prior to study design and the need of standardized operative procedures for EVs isolation and application to biomarkers discovery.

Native and engineered extracellular vesicles for wound healing

Extracellular vesicles (EVs) that act as messengers mediate communication between parent and recipient cells through their contents, including nucleic acids, proteins, and lipids. These endogenous vesicles have emerged as a novel cell-free strategy for the treatment of diseases. EVs can be released by various types of cells with unique biological properties. Recent studies have shown that native EVs are used as therapeutic agents to promote tissue repair by delivering various growth factors and trophic factors including VEGF, EGF, TFN-α, IL-1β, and TGF-β to participate in all physiological processes of wound healing. Furthermore, to improve their specificity, safety, and efficiency for wound healing, the content and surface of EVs can be designed, modified, and engineered. The engineering strategies of EVs are divided into parent cell modification and indirect modification of EVs. The therapeutic potential of current EVs and engineered EVs for wound healing still requires the exploration of their large-scale clinical applications through innovative approaches. Herein, we provide an overview of the current biological knowledge about wound healing and EVs, as well as the application of native EVs in promoting wound healing. We also outline recent advances in engineering EV methodologies to achieve ideal therapeutic potential. Finally, the therapeutic applications of engineered EVs in wound healing are reviewed, and the challenges and prospects for the translation of engineered EVs to clinical applications are discussed.

Murine macrophages or their secretome delivered in alginate dressings enhance impaired wound healing in diabetic mice

Diabetic foot ulceration is a devastating diabetic complication with unmet needs. We explored the efficacy of calcium-crosslinked alginate dressings in topically delivering primary macrophages and their secretome to diabetic wounds. The alginate bandages had a microporous structure that enabled even cell loading with prolonged cell survival and egress following wound placement. In vitro experiments showed that we could successfully differentiate and polarize primary murine bone marrow derived monocytes into M0, M1, M2a and M2c defined states with distinct gene expression, surface protein and secretome profiles. The primary macrophages were delivered in the bandages, migrated within the wounds and were still present for as long as 16 days post-injury. In wounds of db/db mice, treatment with all macrophage subtypes and their secretome, when compared to control, accelerated wound healing. Bulk RNA sequencing analysis and multiplex protein quantification of wound lysates revealed that M2c macrophages conditioned media had the most impact in wound healing affecting processes like neurogenesis, while M1 conditioned media promoted keratinization and epidermal differentiation. Collectively, our results indicate that alginate dressings can serve as a delivery platform for topical treatment of diabetic wounds and that conditioned media from distinctly polarized macrophages is equally or more effective than their parental cells in advancing wound healing and could therefore be a promising and technically advantageous alternative to cell therapy.

Application of Cell-Derived Extracellular Vesicles and Engineered Nanovesicles for Hair Growth: From Mechanisms to Therapeutics

Hair loss is one of the most common disorders that affect both male and female patients. Cell-derived nanovesicles (CDVs) are natural extracellular vesicles and engineered nanovesicles that can carry various biologicals materials such as proteins, lipids, mRNA, miRNA, and DNA. These vesicles can communicate with local or distant cells and are capable of delivering endogenous materials and exogenous drugs for regenerative therapies. Recent studies revealed that CDVs can serve as new treatment strategies for hair growth. Herein, we review current knowledge on the role of CDVs in applications to hair growth. The in-depth understanding of the mechanisms by which CDVs enable therapeutic effects for hair growth may accelerate successful clinical translation of these vesicles for treating hair loss.

Ruyi Jinhuang Powder accelerated diabetic ulcer wound healing by regulating Wnt/β-catenin signaling pathway of fibroblasts In Vivo and In Vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic ulcer is a common complication of diabetes. Therapies of diabetic ulcer are still challenging due to the complicated aetiology. Ruyi Jinhuang Powder (RJP) is gradually adopted to treat diabetic ulcer and has a significant therapeutic effect.

AIM OF THE STUDY

To investigate the therapeutic potential for diabetic ulcer in vivo and in vitro, we explored whether and how RJP influences wound healing in mice and fibroblasts at the tissular, cellular and molecular levels.

MATERIALS AND METHODS

The chemical composition of RJP was identified by HPLC. Streptozotocin (STZ) induced diabetic mice were used to confirm the curative effect of RJP in vivo. Besides, the impact of RJP in stimulating fibroblasts proliferation, migration and reducing inflammation was studied through CCK-8 assay, cell scratch assay, PCR, WB, etc. RESULTS: A total of 17 compounds were identified in RJP by HPLC. Our data indicated that RJP promoted fibroblasts proliferation and migration via activating Wnt/β-catenin signaling pathway. Consistently, RNA-seq analysis of mice skin samples also showed that the shared differentially expressed genes (DEGs) between RJP group and control group were most enriched in wnt signaling pathway. These DEGs were closely related with wound repair. In addition, the anti-inflammation effect of RJP was also confirmed through downregulation of IL-1α, IL-1β, IL-6 and IL-10 expression levels. These biological effects were reduced when the Wnt/β-catenin signaling was blocked. The in vivo study also demonstrated the effect of RJP in improving epidermal wound closure, which was consistent with the in vitro results.

CONCLUSIONS

Topical application of RJP was effective in treating diabetic ulcer. This research is helpful to provide new insights and evidence into the role of RJP in accelerating unhealing wound and reducing wound inflammation.

Hydrogel-based dressings in the treatment of partial thickness experimentally induced burn wounds in rats

Purpose:

To compare four commercially available hydrogel formulations in the healing of partial thickness burns experimentally induced in rats.

Methods:

Wistar rats were used, and after the burn wound induction they were divided into the following treatment groups: G1) NaCl 0.9%; G2) 1% silver sulfadiazine; G3) Debrigel™; G4) Safgel™; G5) Dersani™; G6) Solosite™. The animals were followed during seven, 14 and 30 days after the injury induction. Morphometric, macroscopic and microscopic evaluations were performed.

Results:

The treatment with Dersani™ induced better results during the inflammatory and proliferative phases of the healing process (p<0.05). The animals treated with Safgel™ presented better scaring in the remodeling phase (p<0.05), and the treatment with Dersani™ and Solosite™ induced greater wound closure (p<0.05).

Conclusions:

The hydrogel-based dressings presented beneficial outcomes in the healing of burn wounds experimentally induced in rats due to their ability in maintain the humidity of the wound, in removing the exudate, in promoting cell migration and collagen production during the different phases of the healing process.

Extracellular Vesicles in Facial Aesthetics: A Review

Facial aesthetics involve the application of non-invasive or minimally invasive techniques to improve facial appearance. Currently, extracellular vesicles (EVs) are attracting much interest as nanocarriers in facial aesthetics due to their lipid bilayer membrane, nanosized dimensions, biological origin, intercellular communication ability, and capability to modulate the molecular activities of recipient cells that play important roles in skin rejuvenation. Therefore, EVs have been suggested to have therapeutic potential in improving skin conditions, and these highlighted the potential to develop EV-based cosmetic products. This review summarizes EVs’ latest research, reporting applications in facial aesthetics, including scar removal, facial rejuvenation, anti-aging, and anti-pigmentation. This review also discussed the advanced delivery strategy of EVs, the therapeutic potential of plant EVs, and clinical studies using EVs to improve skin conditions. In summary, EV therapy reduces scarring, rejuvenates aging skin, and reduces pigmentation. These observations warrant the development of EV-based cosmetic products. However, more efforts are needed to establish a large-scale EV production platform that can consistently produce functional EVs and understand EVs’ underlying mechanism of action to improve their efficacy.

Identification of Angiogenic Cargoes in Human Fibroblasts-Derived Extracellular Vesicles and Induction of Wound Healing

A complete redevelopment of the skin remains a challenge in the management of acute and chronic wounds. Recently, the application of extracellular vesicles (EVs) for soft tissue wound healing has received much attention. As fibroblasts are fundamental cells for soft tissues and skin, we investigate the proangiogenic factors in human normal fibroblast-derived EVs (hNF-EVs) and their effects on wound healing. Normal fibroblasts were isolated from human skin tissues and characterized by immunofluorescence (IF) and Western blotting (WB). hNF-EVs were isolated by ultracentrifugation and characterized using transmission electron microscopy and WB. The proangiogenic cargos in hNF-EVs were identified by a TaqMan assay and a protein array. Other in vitro assays, including internalization assays, cell counting kit-8 analysis, scratch wound assays, WBs, and tube formation assays were conducted to assess the effects of hNF-EVs on fibroblasts and endothelial cells. A novel scaffold-free noninvasive delivery of hNF-EVs with or without fibrin glue was applied onto full-thickness skin wounds in mice. The wound healing therapeutical effect of hNF-EVs was assessed by calculating the rate of wound closure and through histological analysis. Isolated hNF was confirmed by verifying the expression of the fibroblast markers vimentin, αSMA, Hsp70, and S100A4. Isolated hNF-EVs showed intact EVs with round morphology, enriched in CD81 and CD63, and devoid of the cell markers GM130, Calnexin, and Cytochrome C. Our TaqMan assay showed that hNF-EVs were enriched in miR130a and miR210, and protein arrays showed enriched levels of the proangiogenic proteins’ vascular endothelial growth factor (VEGF)-D and CXCL8. Next, we found that the internalization of hNF-EVs into hNF increased the proliferation and migration of hNF, in addition to increasing the expression of bFGF, MMP2, and αSMA. The internalization of hNF-EVs into the endothelial cells increased their proliferation and tube formation. A scaffold-free noninvasive delivery of hNF-EVs with or without fibrin glue accelerated the wound healing rate in full-thickness skin wounds in mice, and the treatments increased the cellular density, deposition, and maturation of collagens in the wounds. Moreover, the scaffold-free noninvasive delivery of hNF-EVs with or without fibrin glue increased the VEGF and CD31 expression in the wounds, indicating that hNF-EVs have an angiogenic ability to achieve complete skin regeneration. These findings open up for new treatment strategies to be developed for wound healing. Further, we offer a new approach to the efficient, scaffold-free noninvasive delivery of hNF-EVs to wounds.

Extracellular Vesicles and Acute Kidney Injury: Potential Therapeutic Avenue for Renal Repair and Regeneration

Acute kidney injury (AKI) is a sudden decline of renal function and represents a global clinical problem due to an elevated morbidity and mortality. Despite many efforts, currently there are no treatments to halt this devastating condition. Extracellular vesicles (EVs) are nanoparticles secreted by various cell types in both physiological and pathological conditions. EVs can arise from distinct parts of the kidney and can mediate intercellular communication between various cell types along the nephron. Besides their potential as diagnostic tools, EVs have been proposed as powerful new tools for regenerative medicine and have been broadly studied as therapeutic mediators in different models of experimental AKI. In this review, we present an overview of the basic features and biological relevance of EVs, with an emphasis on their functional role in cell-to-cell communication in the kidney. We explore versatile roles of EVs in crucial pathophysiological mechanisms contributing to AKI and give a detailed description of the renoprotective effects of EVs from different origins in AKI. Finally, we explain known mechanisms of action of EVs in AKI and provide an outlook on the potential clinical translation of EVs in the setting of AKI.

Young fibroblast-derived exosomal microRNA-125b transfers beneficial effects on aged cutaneous wound healing

Aged skin wounds heal poorly, resulting in medical, economic, and social burdens posed by nonhealing wounds. Age-related defects in repair are associated with reduced myofibroblasts and dysfunctional extracellular matrix (ECM) deposition. Bidirectional cell-cell communication involving exosome-borne cargo such as micro RNAs (miRs) has emerged as a critical mechanism for wound healing and aged tissue regeneration. Here we report that at the wound edge, aged fibroblasts display reduced migration and differentiation into myofibroblasts, with impaired ECM deposition, when compared with young tissue. Proper activation of fibroblasts to myofibroblasts may alleviate age-related defects in wound healing. Herein, an exosome-guided cell technique was performed to induce effective wound healing. Supplementing wounds with exosomes isolated from young mouse wound-edge fibroblasts (exosomes^Young) significantly improved the abundance of myofibroblasts and wound healing in aged mice and caused fibroblasts to migrate and transition to myofibroblasts in vitro. To determine the underlying mechanism, we found that exosomal transfer of miR-125b to fibroblasts inhibited sirtuin 7 (Sirt7), thus accelerating myofibroblast differentiation and wound healing in aged mice. Notably, after epidermal inhibition of miR-125b or overexpression of Sirt7 in fibroblasts, migration and myofibroblast transition were perturbed. Our findings thus reveal that miR-125b is transferred through exosomes from young fibroblasts to old fibroblasts contributes to promoting fibroblast migration and transition to counteract aging, suggesting a potential avenue for anti-aging interventions in wound healing.

Human adipose mesenchymal stem cells modulate inflammation and angiogenesis through exosomes

Stem cell-derived exosomes are efficient and safe therapeutic tools for transferring endogenous biological cargo or functional biomolecules for regenerative medicine. The regulation of inflammation and angiogenesis plays a pivotal role in wound healing and tissue regeneration. The purpose of this study was to investigate the anti-inflammatory and pro-angiogenic roles of human adipose mesenchymal stem cell-derived exosomes, focusing on the underlying mechanisms. Exosomes inhibited LPS-induced inflammation by activating ROCK1 and PTEN expression. Moreover, microRNAs (miR-132 and miR-146a) released from exosomes upregulated the expression of pro-angiogenic genes and promoted proliferation activity and tube formation in human umbilical vein endothelial cells. Exosomal effects were verified using ROCK1/PTEN inhibitors for anti-inflammation and miR-132/miR-146a inhibitors for pro-angiogenesis. Our findings suggest that exosomes exert anti-inflammatory effects by targeting the ROCK1/PTEN pathway and exhibit pro-angiogenic effects via delivery of miR-132 and miR-146a. Taken together, these results suggest that exosomes may be promising therapeutic candidates for curing diseases involved in inflammation and angiogenesis.

Extracellular Vesicles in Skin Wound Healing

Each year, millions of individuals suffer from a non-healing wound, abnormal scarring, or injuries accompanied by an infection. For these cases, scientists are searching for new therapeutic interventions, from which one of the most promising is the use of extracellular vesicles (EVs). Naturally, EV-based signaling takes part in all four wound healing phases: hemostasis, inflammation, proliferation, and remodeling. Such an extensive involvement of EVs suggests exploiting their action to modulate the impaired healing phase. Furthermore, next to their natural wound healing capacity, EVs can be engineered for better defined pharmaceutical purposes, such as carrying specific cargo or targeting specific destinations by labelling them with certain surface proteins. This review aims to promote scientific awareness in basic and translational research of EVs by summarizing the current knowledge about their natural role in each stage of skin repair and the most recent findings in application areas, such as wound healing, skin regeneration, and treatment of dermal diseases, including the stem cell-derived, plant-derived, and engineered EVs.

Cytotoxicity and Effect of Topical Application of Tranexamic Acid on Human Fibroblast in Spine Surgery

OBJECTIVE

In spinal surgery, considerable blood loss is increasingly treated with the local application of tranexamic acid (TXA). However, little is known about its cytotoxicity and effect on human fibroblasts. This study was to identify the effect of TXA solution on human fibroblast at different concentrations and exposure times in vitro.

METHODS

To mimic the actual clinical situation, human fibroblasts were subjected to both limited and chronic exposure to various clinically relevant concentrations of TXA to mimic different ways of topical administration. At time points after treatment, the viability, proliferation, apoptosis, collagen synthesis, adhesion, and migration of fibroblasts were analyzed in vitro.

RESULTS

Limited exposure (10 minutes) to a high concentration of TXA (100 mg/mL) did not affect the viability, proliferation, and apoptosis of fibroblasts, and chronic exposure to low concentration of TXA (≤12.5 mg/mL) exerted little effect on viability, proliferation, apoptosis, collagen synthesis, adhesion, and migration of human fibroblasts (P > 0.05). However, the chronic exposure to a high concentration of TXA (≥25 mg/mL) can inhibit the viability, proliferation, collagen synthesis, adhesion and migration, and induce apoptosis of fibroblasts.

CONCLUSIONS

Although limited exposure to high concentration of TXA and chronic exposure to low concentration of TXA exerted little effect on fibroblasts, chronic exposure to high concentration of TXA can lead to fibroblast injury.

Identification of Angiogenic Cargo in Extracellular Vesicles Secreted from Human Adipose Tissue-Derived Stem Cells and Induction of Angiogenesis In Vitro and In Vivo

Angiogenesis is defined as the generation of new blood vessels or the sprouting of endothelial cells from a pre-existing vascular network. Angiogenesis occurs during the growth and development of an organism, the response of organs or tissues to injury, and during cancer development and progression. The majority of studies on stem-cell-derived extracellular vesicles (EVs) have used cell lines, and have primarily focused on well-known solitary proteins. Here, we isolated stem cells from human adipose tissue (ADSCs), and we isolated EVs from them (ADSC-EVs). The ADSC-EVs were characterised and 20 angiogenic proteins were analysed using an angiogenic antibody array. Furthermore, we analysed the ability of ADSC-EVs to induce angiogenesis in vitro and in vivo. ADSC-EVs were positive for CD81 and negative for GM130, calnexin, and cytochrome-C. ADSC-EVs showed typical EV spherical morphology and were ~200 nm in size. ADSC-EVs were found to contain angiogenic proteins as cargo, among which interleukin 8 (IL-8) was the most abundant, followed by chemokine (C-C motif) ligand 2 (CCL2), a tissue inhibitor of metalloproteinases 1 (TIMP-1), TIMP-2, and vascular endothelial growth factor-D (VEGF-D). ADSC-EVs treatment increased the proliferation, migration, total vessel length, total number of junctions, and junction density of endothelial cells in vitro. The results of an in vivo Matrigel plug assay revealed that ADSC-EVs induced more blood vessels in the Matrigel compared with the control. These results demonstrate that ADSC-EVs contain angiogenic proteins as cargo and promote angiogenesis in vitro and in vivo. Therefore, ADSC-EVs have potential for therapeutic use in ischaemia.