Search

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.

Electrospun nanofibrous membranes (eNFMs) have been extensively developed for bio-applications due to their structural and compositional similarity to the natural extracellular matrix. However, the emergence of antibiotic resistance in bacterial infections significantly impedes the further development and applications of eNFMs. The development of antibacterial nanomaterials substantially nourishes the engineering design of antibacterial eNFMs for combating bacterial infections without relying on antibiotics. Herein, a comprehensive review of diverse fabrication techniques for incorporating antibacterial nanomaterials into eNFMs is presented, encompassing an exhaustive introduction to various nanomaterials and their bactericidal mechanisms. Furthermore, the latest achievements and breakthroughs in the application of these antibacterial eNFMs in tissue regenerative therapy, mainly focusing on skin, bone, periodontal and tendon tissues regeneration and repair, are systematically summarized and discussed. In particular, for the treatment of skin infection wounds, we highlight the antibiotic-free antibacterial therapy strategies of antibacterial eNFMs, including (i) single model therapies such as metal ion therapy, chemodynamic therapy, photothermal therapy, and photodynamic therapy; and (ii) multi-model therapies involving arbitrary combinations of these single models. Additionally, the limitations, challenges and future opportunities of antibacterial eNFMs in biomedical applications are also discussed. We anticipate that this comprehensive review will provide novel insights for the design and utilization of antibacterial eNFMs in future research.

Abstract Background Burns cause serious physical and psychological harm to patients, placing a heavy burden on the global healthcare system. Our previous study detailed the epidemiological characteristics of burn injuries in Chinese inpatients from 2009 to 2018. Interestingly, the anatomic locations of burn injuries vary by gender, age, provinces, and outcomes among different causes. Therefore, this current study aims to analyze the characteristics of burn injuries in inpatients with various burn sites by collecting data in China from 2009 to 2018. This analysis will inform future healthcare system decisions and provide effective strategies. Methods Burns inpatients from 196 hospitals across 31 provinces in China were included in the study, covering the period from 2009 to 2018. The data collected encompassed information on gender, age, etiology, regions, clinical outcomes, and anatomical locations of the injuries. Data analysis was conducted using Microsoft Excel 2007. Results From 2009 to 2018, a total of 333,995 burns inpatients were recorded. The most vulnerable parts to burns were multiple burn sites (230,090, 68.89%). Women were more susceptible to lower limb burns (15,608, 14%), while men were more prone to eye injuries (8,387, 3.37%) and hand burns (6,119, 2.75%). The age group of 0–10 years was the most vulnerable to burns across all body areas, including internal organs. In China, individuals aged 20–50 years were at a higher risk of head and neck burns compared to other age groups. The Han population showed increased vulnerability to eye injuries (2.12 times higher than minorities), respiratory tract issues (2.09 times higher than minorities), and trunk burns (1.83 times higher than minorities), while being less susceptible to internal organ injuries (0.23 times fewer than minorities) and lower limb burns (0.78 times fewer than minorities). The southwest region had the highest proportion of burns inpatients with burns affecting single body parts, whereas the eastern area had the highest rates of respiratory tract burns (0.85%) and multiple burn sites (80.64%). Scalding was identified as the most common cause of burns, while flame burns (769, 55.81%) and chemical burns (438, 47.35%) were the main causes of respiratory tract and internal organ injuries, respectively. Conclusions This study provides an initial description of characteristics of burns inpatients with various anatomic locations of burns in China over the past decade. Our findings will contribute to the most up-to-date clinical evidence database for healthcare planning and prevention initiatives in both China and other countries.

Persistent inflammatory responses often occur when bacteria and other microorganisms frequently invade and colonize open wounds and eventually result in the formation of chronic wounds. Therefore, achieving real-time detection of invasive bacteria accurately and promptly is essential for efficient wound management and accelerating the healing process. Recently, flexible wearable sensors have garnered significant attention, especially those designed for monitoring real-time biophysical or biochemical signals in wound sites in a minimally invasive manner. They provide more precise and continuous monitoring data, making them as emerging tools for clinical diagnostics. In this review, we first discuss the species and community distribution of different types of bacteria in chronic wounds. Next, we introduce currently developed techniques for detecting bacteria at wound sites. Following that, we discuss the recent progress and unresolved issues of various flexible wearable sensors in detecting bacteria at wound sites. We believe that this review can provide meaningful guidance for the development of flexible wearable sensors for bacteria detection.

Abstract Background Understanding factors associated with antiretroviral treatment (ART) adherence is crucial for ART success among people living with HIV (PLHIV) in the “test and treat” era. Multiple psychosocial factors tend to coexist and have a syndemic effect on ART adherence. We aimed to explore factors associated with ART adherence and the syndemic effect of multiple psychosocial factors on ART adherence among PLHIV newly starting ART in Guangdong Province, China. Methods Newly diagnosed PLHIV from six cities in Guangdong Province were recruited between May 2018 and June 2019, and then followed up from May 2019 to August 2020. Baseline and follow-up data were collected from a questionnaire and the national HIV surveillance system, the follow-up data of which were analyzed in this study. A Center for Adherence Support Evaluation (CASE) index > 10 points was defined as optimal ART adherence, which was measured via participants’ self-reported adherence during follow-up survey. Multivariable logistic regression was used to identify factors associated with ART adherence. Exploratory factor analysis (EFA) and multi-order latent variable structural equation modeling (SEM) were performed to explore the syndemic effect of multiple psychosocial factors on ART adherence. Results A total of 734 (68.53%) follow-up participants were finally included in this study among the 1071 baseline participants, of whom 91.28% (670/734) had self-reported optimal ART adherence. Unemployment (aOR = 1.75, 95%CI: 1.01–3.02), no medication reminder (aOR = 2.28, 95%CI: 1.09–4.74), low medication self-efficacy (aOR = 2.28, 95%CI: 1.27–4.10), low social cohesion (aOR = 1.82, 95%CI: 1.03–3.19), no social participation (aOR = 5.65, 95%CI: 1.71–18.63), and ART side effects (aOR = 0.46, 95%CI: 0.26–0.81) were barriers to optimal ART adherence. The EFA and second-order latent variable SEM showed a linear relationship (standardized coefficient = 0.43, P

Abstract Chronic wounds are a major complication in patients with diabetes. Here, we identify a therapeutic circRNA and load it into small extracellular vesicles (sEVs) to treat diabetic wounds in preclinical models. We show that circCDK13 can stimulate the proliferation and migration of human dermal fibroblasts and human epidermal keratinocytes by interacting with insulin-like growth factor 2 mRNA binding protein 3 in an N6-Methyladenosine-dependent manner to enhance CD44 and c-MYC expression. We engineered sEVs that overexpress circCDK13 and show that local subcutaneous injection into male db/db diabetic mouse wounds and wounds of streptozotocin-induced type I male diabetic rats could accelerate wound healing and skin appendage regeneration. Our study demonstrates that the delivery of circCDK13 in sEVs may present an option for diabetic wound treatment.

Abstract With the aging and obesity era, the increasing incidence of diabetes and diabetic complications, especially the non‐healing wounds, imposes a serious economic burden on both patients and society. The complex microenvironments, including hyperglycemia, bacterial infection, ischemia, and nerve damage, lead to the prolonged inflammation and proliferation phase of diabetic wounds. Mesenchymal stem cell‐derived small extracellular vesicles (MSC‐sEVs), which contain a rich variety of therapeutic molecules, have been chased for decades because of their potential roles in cellular communication, tissue regeneration, and drug delivery. As powerful tools for the controlled‐sustained release of sEVs, biocompatible hydrogels have been applied in a wide range of biomedical applications. Herein, we first summarize the pathological features of diabetic wounds, such as angiopathy, neuropathy, and immune cell dysfunction. Then, we discuss the biological properties, therapeutic performance, and stability of pure MSC‐sEVs. After that, we discuss the components, application patterns, and responsiveness of hydrogels. Next, we discuss the loading avenues of MSC‐sEVs into hydrogel, the release behaviors of sEVs from hydrogels, and the influence of the crosslinking method on the hydrogel‐sEV composites. Finally, we provide an overview of the current applications of hydrogels loaded with MSC‐sEVs as a novel cell‐free tissue engineering system in managing diabetic wounds and propose the critical unsolved issues. This review is expected to provide meaningful guidance for developing a novel cell‐free tissue engineering system for diabetic wound management.

Loss of sweat glands (SwGs) commonly associated with extensive skin defects is a leading cause of hyperthermia and heat stroke. In vivo tissue engineering possesses the potential to take use of the body natural ability to regenerate SwGs, making it more conducive to clinical translation. Despite recent advances in regenerative medicine, reconstructing SwG tissue with the same structure and function as native tissue remains challenging. Elucidating the SwG generation mechanism and developing biomaterials for in vivo tissue engineering is essential for understanding and developing in vivo SwG regenerative strategies. Here, we outline the cell biology associated with functional wound healing and the characteristics of bioactive materials. We critically summarize the recent progress in bioactive material-based cell modulation approaches for in vivo SwG regeneration, including the recruitment of endogenous cells to the skin lesion for SwG regeneration and in vivo cellular reprogramming for SwG regeneration. We discussed the re-establishment of microenvironment via bioactive material-mediated regulators. Besides, we offer promising perspectives for directing in situ SwG regeneration via bioactive material-based cell-free strategy, which is a simple and effective approach to regenerate SwG tissue with both fidelity of structure and function. Finally, we discuss the opportunities and challenges of in vivo SwG regeneration in detail. The molecular mechanisms and cell fate modulation of in vivo SwG regeneration will provide further insights into the regeneration of patient-specific SwGs and the development of potential intervention strategies for gland-derived diseases.

Abstract Delayed wound healing is a major complication of diabetes, and is associated with impaired cellular functions. Current treatments are unsatisfactory. Based on the previous reports on microRNA expression in small extracellular vesicles (sEVs), miR‐17‐5p‐engineered sEVs (sEVs17‐OE) and encapsulated them in gelatin methacryloyl (GelMA) hydrogel for diabetic wounds treatment are fabricated. SEVs17‐OE are successfully fabricated with a 16‐fold increase in miR‐17‐5p expression. SEVs17‐OE inhibited senescence and promoted the proliferation, migration, and tube formation of high glucose‐induced human umbilical vein endothelial cells (HG‐HUVECs). Additionally, sEVs17‐OE also performs a promotive effect on high glucose‐induced human dermal fibroblasts (HG‐HDFs). Mechanism analysis showed the expressions of p21 and phosphatase and tensin homolog (PTEN), as the target genes of miR‐17‐5p, are downregulated significantly by sEVs17‐OE. Accordingly, the downstream genes and pathways of p21 and PTEN, are activated. Next, sEVs17‐OE are loaded in GelMA hydrogel to fabricate a novel bioactive wound dressing and to evaluate their effects on diabetic wound healing. Gel‐sEVs17‐OE effectively accelerated wound healing by promoting angiogenesis and collagen deposition. The cellular mechanism may be associated with local cell proliferation. Therefore, a novel bioactive wound dressing by loading sEVs17‐OE in GelMA hydrogel, offering an option for chronic wound management is successfully fabricated.

Abstract The scar repair inevitably causes damage of skin function and loss of skin appendages such as hair follicles (HF). It is of great challenge in wound repair that how to intervene in scar formation while simultaneously remodeling HF niche and inducing in situ HF regeneration. Here, chemical reprogramming techniques are used to identify a clinically chemical cocktail (Tideglusib and Tamibarotene) that can drive fibroblasts toward dermal papilla cell (DPC) fate. Considering the advantage of biomaterials in tissue repair and their regulation in cell behavior that may contributes to cellular reprogramming, the artificial HF seeding (AHFS) hydrogel microspheres, inspired by the natural processes of “seeding and harvest”, are constructed via using a combination of liposome nanoparticle drug delivery system, photoresponsive hydrogel shell, positively charged polyamide modification, microfluidic and photocrosslinking techniques. The identified chemical cocktail is as the core nucleus of AHFS. In vitro and in vivo studies show that AHFS can regulate fibroblast fate, induce fibroblast‐to‐DPC reprogramming by activating the PI3K/AKT pathway, finally promoting wound healing and in situ HF regeneration while inhibiting scar formation in a two‐pronged translational approach. In conclusion, AHFS provides a new and effective strategy for functional repair of skin wounds.

BackgroundNormal hepatic functional reserve is the key to avoiding liver failure after liver surgery. This study investigated the assessment of hepatic functional reserve using liver shear wave velocity (LSWV) combined with biochemical indicators, tumor volume, and portal vein diameter.MethodsIn this single-center prospective study, a total of 123 patients with hepatocellular carcinoma (HCC) were divided into a test group (n=92) and a validation group (n=31). All patients were Child-Pugh grade A. The indocyanine green retention rate at 15 min (ICG-R15), liver shear wave velocity (LSWV), portal vein diameter (Dpv), alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), γ-glutamyl transpeptidase (γ-GGT), albumin (ALB), prothrombin time (PT), and also liver tumor volume (maximum diameter ≤5 cm) were measured. In the test group, multiple parameters were used to evaluate hepatic functional reserve, and the multiparametric model was established. Receiver operating characteristic (ROC) curve analysis was conducted to assess the diagnostic performance of the multiparametric model. In the validation group, the predictive effectiveness of the multiparametric model was analyzed using consistency tests.ResultsIt was revealed that LSWV, ALB, and PT were statistically significant in evaluation of the hepatic functional reserve (P

Abstract Hypertrophic scar formation is influenced by the intricate interplay between fibroblasts and endothelial cells. In this study, we investigated this relationship using in vitro and in vivo models. Clinical observations revealed distinct morphological changes and increased vascularity at pathological scar sites. Further analysis using OCTA, immunohistochemistry, and immunofluorescence confirmed the involvement of angiogenesis in scar formation. Our indirect co‐culture systems demonstrated that endothelial cells enhance the proliferation and migration of fibroblasts through the secretion of cytokines including VEGF, PDGF, bFGF, and TGF‐β. Additionally, a suspended co‐culture multicellular spheroid model revealed molecular‐level changes associated with extracellular matrix remodeling, cellular behaviors, inflammatory response, and pro‐angiogenic activity. Furthermore, KEGG pathway analysis identified the involvement of TGF‐β, IL‐17, Wnt, Notch, PI3K‐Akt, and MAPK pathways in regulating fibroblasts activity. These findings underscore the critical role of fibroblasts‐endothelial cells crosstalk in scar formation and provide potential targets for therapeutic intervention. Understanding the molecular mechanisms underlying this interplay holds promise for the development of innovative approaches to treat tissue injuries and diseases.

Neutrophil extracellular traps (NETs) have been considered a significant unfavorable factor for wound healing in diabetes, but the mechanisms remain unclear. The therapeutic application of small extracellular vesicles (sEVs) derived from mesenchymal stem cells (MSCs) has received considerable attention for their properties. Hypoxic preconditioning is reported to enhance the therapeutic potential of MSC-derived sEVs in regenerative medicine. Therefore, the aim of this study is to illustrate the detailed mechanism of NETs in impairment of diabetic wound healing and develop a promising NET-targeting treatment based on hypoxic pretreated MSC-derived sEVs (Hypo-sEVs). Excessive NETs were found in diabetic wounds and in high glucose (HG)-induced neutrophils. Further research showed that high concentration of NETs impaired the function of fibroblasts through activating endoplasmic reticulum (ER) stress. Hypo-sEVs efficiently promoted diabetic wound healing and reduced the excessive NET formation by transferring miR-17–5p. Bioinformatic analysis and RNA interference experiment revealed that miR-17–5p in Hypo-sEVs obstructed the NET formation by targeting TLR4/ROS/MAPK pathway. Additionally, miR-17–5p overexpression decreased NET formation and overcame NET-induced impairment in fibroblasts, similar to the effects of Hypo-sEVs. Overall, we identify a previously unrecognized NET-related mechanism in diabetic wounds and provide a promising NET-targeting strategy for wound treatment.

Abstract The ageing process is a systemic decline from cellular dysfunction to organ degeneration, with more predisposition to deteriorated disorders. Rejuvenation refers to giving aged cells or organisms more youthful characteristics through various techniques, such as cellular reprogramming and epigenetic regulation. The great leaps in cellular rejuvenation prove that ageing is not a one-way street, and many rejuvenative interventions have emerged to delay and even reverse the ageing process. Defining the mechanism by which roadblocks and signaling inputs influence complex ageing programs is essential for understanding and developing rejuvenative strategies. Here, we discuss the intrinsic and extrinsic factors that counteract cell rejuvenation, and the targeted cells and core mechanisms involved in this process. Then, we critically summarize the latest advances in state-of-art strategies of cellular rejuvenation. Various rejuvenation methods also provide insights for treating specific ageing-related diseases, including cellular reprogramming, the removal of senescence cells (SCs) and suppression of senescence-associated secretory phenotype (SASP), metabolic manipulation, stem cells-associated therapy, dietary restriction, immune rejuvenation and heterochronic transplantation, etc. The potential applications of rejuvenation therapy also extend to cancer treatment. Finally, we analyze in detail the therapeutic opportunities and challenges of rejuvenation technology. Deciphering rejuvenation interventions will provide further insights into anti-ageing and ageing-related disease treatment in clinical settings.

The incorporation of vasculature is known to be effective in tissue or organ functional regeneration. However, a vague understanding of the interaction between epidermal appendages and their vascular niches is a foremost obstacle to obtaining sweat gland (SG)-specific vasculature units. Here, we map their precise anatomical connections and report that the interplay between SG cells (SGCs) and the surrounding vascular niche is key for glandular development and homeostasis maintenance. To replicate this interplay in vitro, we used three-dimensional (3D) bioprinting to generate reproducible SGC spheroids from differentiated adipose-derived mesenchymal stem cells (ADSCs). With dermal microvascular endothelial cells (DMECs), sacrificial templates made from poly (ε-caprolactone) (PCL) were fabricated to pattern the vascular niche. This interplay model promoted physiologically relevant vascularized glandular morphogenesis in vitro and in vivo. We identified a reciprocal regulatory mechanism for promoting SGs regeneration via contact-independent cell communication and direct cell-cell interactions between SGs and the vasculature. We envision the successful use of our approach for vascularized organ regeneration in the near future.

Abstract Diabetic wounds have imposed a significant burden on both patients and society with prolonged healing processes hindered by dysfunctional skin repair cells. Small extracellular vesicles (sEVs), as the important media for intercellular communications, show promising therapeutic potential in treating diabetic wounds by restoring cellular functions. However, low yields and limited bio‐function of sEVs greatly challenge their large‐scale clinical use. Here, we briefly overview the biogenesis and cellular uptake of sEVs, emphasize current advances in improving the yields of sEVs and optimizing the function of sEVs with engineering approaches, and summarize the applications of engineered sEVs in diabetic wound treatment. Furthermore, the undissolved issues during the clinical transformation of engineered sEVs are also discussed. This critical review aims to provide meaningful guidance for future applications of engineered sEVs in the management of diabetic wounds.

Abstract Ferroptosis plays an essential role in the development of diabetes and its complications, suggesting potential therapeutic strategies targeting ferroptosis. Secretory autophagosomes (SAPs) carrying cytoplasmic cargoes have been recognized as novel nano‐warrior to defeat diseases. Here, it is hypothesized that SAPs derived from human umbilical vein endothelial cells (HUVECs) can restore the function of skin repair cells by inhibiting ferroptosis to promote diabetic wound healing. High glucose (HG)‐caused ferroptosis in human dermal fibroblasts (HDFs) is observed in vitro, which results in impaired cellular function. SAPs successfully inhibit ferroptosis in HG‐HDFs, thereby improving their proliferation and migration. Further research show that the inhibitory effect of SAPs on ferroptosis resulted from a decrease in endoplasmic reticulum (ER) stress‐regulated generation of free ferrous ions (Fe2+) in HG‐HDFs and an increase in exosome release to discharge free Fe2+ from HG‐HDFs. Additionally, SAPs promote the proliferation, migration, and tube formation of HG‐HUVECs. Then the SAPs are loaded into gelatin‐methacryloyl (GelMA) hydrogels to fabricate functional wound dressings. The results demonstrate the therapeutic effect of Gel‐SAPs on diabetic wounds by restoring the normal behavior of skin repair cells. These findings suggest a promising SAP‐based strategy for the treatment of ferroptosis‐associated diseases.

Abstract Unhealable diabetic wounds need to be addressed with the help of newer, more efficacious strategies. Exosomes combined with biomaterials for sustained delivery of therapeutic agents are expected to bring new hope for chronic wound treatment. Here, the engineered exosomes modified for efficiently loading miR146a and attaching to silk fibroin patch (SFP) were demonstrated to promote diabetic wound healing. Silk fibroin binding peptide (SFBP) was screened through phage display, and SFBP-Gluc-MS2 (SGM) and pac-miR146a-pac fusion protein were constructed. The designed exosomes (SGM-Exos, miR146a-Exos, and SGM-miR146a-Exos) were isolated from the engineered placental mesenchymal stem cells (PMSCs) transduced with SGM or/and pac-miR146a-pac protein. Gluc signals indicated SGM-Exo@SFP markedly increased the binding rate and the stability of SGM-Exo. Moreover, the loading efficiency of miR146a in SGM-miR146a-Exos was ten-fold higher than that in miR146a-Exos. Superior to untreated, SGM-miR146a-Exo-only treated, and SFP-only treated groups, SGM-miR146a-Exo@SFP drived wound healing associated with less inflammation, collagen deposition, and neovascularization. The transcriptomics analysis suggested anti-inflammatory and regenerative effects with SGM-miR146a-Exo@SFP treatment. Here, we show efficient exosome@biomaterial-based miRNA delivery systems for regenerative medicine and tissue engineering.

Abstract Mesenchymal stem cell (MSC)-based therapy has been considered as a promising approach targeting a variety of intractable diseases due to remarkable multiple effect of MSCs, such as multilineage differentiation, immunomodulatory property, and pro-regenerative capacity. However, poor engraftment, low survival rate of transplanted MSC, and impaired donor-MSC potency under host age/disease result in unsatisfactory therapeutic outcomes. Enhancement strategies, including genetic manipulation, pre-activation, and modification of culture method, have been investigated to generate highly functional MSC, and approaches for MSC pre-activation are highlighted. In this review, we summarized the current approaches of MSC pre-activation and further classified, analysed the scientific principles and main characteristics of these manipulations, and described the pros and cons of individual pre-activation strategies. We also discuss the specialized tactics to solve the challenges in this promising field so that it improves MSC therapeutic functions to serve patients better.

Abstract. Background:. Sweat secreted by eccrine sweat glands is transported to the skin surface through the lumen. The eccrine sweat gland develops from the initial solid bud to the final gland structure with a lumen, but how the lumen is formed and the mechanism of lumen formation have not yet been fully elucidated. This study aimed to investigate the mechanism of lumen formation of eccrine gland organoids (EGOs). Methods:. Human eccrine sweat glands were isolated from the skin for tissue culture, and the primary cultured cells were collected and cultured in Matrigel for 14 days in vitro. EGOs at different development days were collected for hematoxylin and eosin (H&E) staining to observe morphological changes and for immunofluorescence staining of proliferation marker Ki67, cellular motility marker filamentous actin (F-actin), and autophagy marker LC3B. Western blotting was used to detect the expression of Ki67, F-actin, and LC3B. Moreover, apoptosis was detected using a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis assay kit, and the expression of poly (ADP-ribose) polymerase and Caspase-3 was detected by Western blot. In addition, 3-methyladenine (3MA) was used as an autophagy inhibitor to detect whether the formation of sweat glands can be effectively inhibited. Results:. The results showed that a single gland cell proliferated rapidly and formed EGOs on day 4. The earliest lumen formation was observed on day 6. From day 8 to day 14, the rate of lumen formation in EGOs increased significantly. The immunofluorescence and Western blot analyses showed that the expression of Ki67 gradually decreased with the increase in days, while the F-actin expression level did not change. Notably, the expression of autophagy marker LC3B was detected in the interior cells of EGOs as the apoptosis signal of EGOs was negative. Compared with the control group, the autophagy inhibitor 3MA can effectively limit the formation rate of the lumen and reduce the inner diameter of EGOs. Conclusion:. Using our model of eccrine gland 3D-reconstruction in Matrigel, we determined that autophagy rather than apoptosis plays a role in the lumen formation of EGOs.

BackgroundChronic wounds are a complex medical problem. With the difficulty of skin healing, the microbial ecology of chronic wounds is an essential factor affecting wound healing. High-throughput sequencing (HTS) technology is a vital method to reveal the microbiome diversity and population structure of chronic wounds.ObjectiveThe aim of this paper was to delineate the scientific output characteristics, research trends, hotspots and frontiers of HTS technologies related to chronic wounds globally over the past 20 years.MethodsWe searched the Web of Science Core Collection (WoSCC) database for articles published between 2002 and 2022 and their full record information. The Bibliometrix software package was used to analyze bibliometric indicators and VOSviewer visualization analysis results.ResultsUltimately, a total of 449 original articles were reviewed, and the results showed that the number of annual publications (Nps) about HTS associated with chronic wounds has steadily increased over the last 20 years. The United States and China produce the most articles and have the highest H-index, while the United States and England have the largest number of citations (Nc) in this field. The University of California, Wound Repair and Regeneration and National Institutes of Health Nih United States were the most published institutions, journals and fund resources, respectively. The global research could be divided into 3 clusters as follows: microbial infection of chronic wounds, the healing process of wounds and microscopic processes, skin repair mechanism stimulated by antimicrobial peptides and oxidative stress. In recent years, “wound healing”, “infections”, “expression”, “inflammation”, “chronic wounds”, “identification” and “bacteria” “angiogenesis”, “biofilms” and “diabetes” were the most frequently used keywords. In addition, research on “prevalence”, “gene expression”, “inflammation” and “infection” has recently become a hotspot.ConclusionsThis paper compares the research hotspots and directions in this field globally from the perspectives of countries, institutions and authors, analyzes the trend of international cooperation, and reveals the future development direction of the field and research hotspots of great scientific research value. Through this paper, we can further explore the value of HTS technology in chronic wounds to better solve the problem of chronic wounds.

Chronic skin inflammatory diseases including atopic dermatitis (AD) and psoriasis have been considered uncontrolled inflammatory responses, which have usually troubled patients around the world. Moreover, the recent method to treat AD and psoriasis has been based on the inhibition, not regulation, of the abnormal inflammatory response, which can induce a number of side effects and drug resistance in long-term treatment. Mesenchymal stem/stromal cells (MSCs) and their derivatives have been widely used in immune diseases based on their regeneration, differentiation, and immunomodulation with few adverse effects, which makes MSCs a promising treatment for chronic skin inflammatory diseases. As a result, in this review, we aim to systematically discuss the therapeutic effects of various resources of MSCs, the application of preconditioning MSCs and engineering extracellular vesicles (EVs) in AD and psoriasis, and the clinical evaluation of the administration of MSCs and their derivatives, which can provide a comprehensive vision for the application of MSCs and their derivatives in future research and clinical treatment.

Various intractable inflammatory diseases caused by disorders of immune systems have pressed heavily on public health. Innate and adaptive immune cells as well as secreted cytokines and chemokines are commanders to mediate our immune systems. Therefore, restoring normal immunomodulatory responses of immune cells is crucial for the treatment of inflammatory diseases. Mesenchymal stem cell derived extracellular vesicles (MSC-EVs) are nano-sized double-membraned vesicles acting as paracrine effectors of MSCs. MSC-EVs, containing a variety of therapeutic agents, have shown great potential in immune modulation. Herein, we discuss the novel regulatory functions of MSC-EVs from different sources in the activities of innate and adaptive immune cells like macrophages, granulocytes, mast cells, natural killer (NK) cells, dendritic cells (DCs) and lymphocytes. Then, we summarize the latest clinical trials of MSC-EVs in inflammatory diseases. Furthermore, we prospect the research trend of MSC-EVs in the field of immune modulation. Despite the fact that the research on the role of MSC-EVs in regulating immune cells is in infancy, this cell-free therapy based on MSC-EVs still offers a promising solution for the treatment of inflammatory diseases.

Blood-brain barrier (BBB) is the most important component of central nervous system (CNS) to keep toxins and pathogens from CNS. Although our studies demonstrated that using interleukin-6 antibodies (IL-6-AB) reversed the increased permeability of BBB, IL-6-AB is limited in their application that only could be used a few hours before surgery and seemed delayed the surgical wounds healing process, which urges us to find another more effective method. In this study, we employed the C57BL/6J female mice to investigate the potential effects of umbilical cord-derived mesenchymal stem cells (UC-MSCs) transplantation on BBB dysfunction induced by surgical wound. Compared to IL-6-AB, the transplantation of UC-MSCs more effectively decreased the BBB permeability after surgical wound evaluated by dextran tracer (immunofluorescence imaging and luorescence quantification). In addition, UC-MSCs can largely decrease the ratio of proinflammatory cytokine IL-6 to the anti-inflammatory cytokine IL-10 in both serum and brain tissue after surgical wound. Moreover, UC-MSCs successfully increased the levels of tight junction proteins (TJs) in BBB such as ZO-1, Occludin, and Claudin-5 and extremely decreased the level of matrix metalloproteinase-9 (MMP-9). Interestingly, UC-MSCs treatment also had positive effects on wound healing while protecting the BBB dysfunction induced by surgical wound compared to IL-6-AB treatment. These findings suggest that UC-MSCs transplantation is a highly efficient and promising approach on protecting the integrity of BBB which caused by peripheral traumatic injuries.

BackgroundCommunication between fibroblasts and endothelial cells is essential for skin wound repair and regeneration. Extracellular vesicles (EVs) are crucial for intracellular communication by transporting active molecules. However, whether EVs derived from diabetic fibroblasts can perform the nomal communication function is unclear. Here, we compared the effects of EVs from human skin fibroblasts (HSFs) induced with or without HG on the angiogenic function of endothelial cells and wound healing.MethodsWe first collected EVs from HSFs cultured with normal glucose concentration (NG-EVs) or with HG concentration (HG-EVs) and applied them to treat human umbilical vein endothelial cells (HUVECs). The cells were divided into three groups: control group, NG-EVs group, and HG-EVs group. We then examined the proliferation, migration, apoptosis, and tube formation of HUVECs. To illustrate the mechanism, the expression of β-catenin, GSK-3β, and p-GSK-3β was detected by western-blot. Finally, NG-EVs or HG-EVs were used to treat the wounds of mice to determine their role in wound closure.ResultsBy DNA content detection, Annexin V/PI staining, and EdU staining, we found that NG-EVs promoted HUVEC proliferation, while HG-EVs exhibited an opposite effect (p

Neurological degeneration after neuroinflammation, such as that resulting from Alzheimer’s disease (AD), stroke, multiple sclerosis (MS), and post-traumatic brain injury (TBI), is typically associated with high mortality and morbidity and with permanent cognitive dysfunction, which places a heavy economic burden on families and society. Diagnosing and curing these diseases in their early stages remains a challenge for clinical investigation and treatment. Recent insight into the onset and progression of these diseases highlights the permeability of the blood–brain barrier (BBB). The primary factor that influences BBB structure and function is inflammation, especially the main cytokines including IL-1β, TNFα, and IL-6, the mechanism on the disruption of which are critical component of the aforementioned diseases. Surprisingly, the main cytokines from systematic inflammation can also induce as much worse as from neurological diseases or injuries do. In this review, we will therefore discuss the physiological structure of BBB, the main cytokines including IL-1β, TNFα, IL-6, and their mechanism on the disruption of BBB and recent research about the main cytokines from systematic inflammation inducing the disruption of BBB and cognitive impairment, and we will eventually discuss the need to prevent the disruption of BBB.

With the acceleration of population aging and the changes of disease spectrum, the number of wound patients has increased annually in the past 20 years, which has become a major problem in terms of China's medical and health work. To address this challenge, the National Health Commission of China issued a notice in November 2019, requiring qualified medical and health institutions to establish wound repair departments to strengthen the standardized diagnosis and treatment management of various wound patients. This article introduces the establishment process of the wound repair discipline in China, as well as the practice and experience of building a high-level wound repair department in Chinese hospitals, hoping that it can be used for reference by peers.

Eccrine sweat glands (ESGs) perform critical functions in temperature regulation in humans. Foxa1 plays an important role in ESG maturation and sweat secretion. Its molecular mechanism, however, remains unknown. This study investigated the expression of Foxa1 and Na-K-ATPase (NKA) in rat footpads at different development stages using immunofluorescence staining, qRT-PCR, and immunoblotting. Also, bioinformatics analysis and Foxa1 overexpression and silencing were employed to evaluate Foxa1 regulation of NKA. The results demonstrated that Foxa1 was consistently expressed during the late stages of ESGs and had a significant role in secretory coil maturation during sweat secretion. Furthermore, the mRNA abundance and protein expression of NKA had similar accumulation trends to those of Foxa1, confirming their underlying connections. Bioinformatics analysis revealed that Foxa1 may interact with these two proteins via binding to conserved motifs in their promoter regions. Foxa1 gain-of-function and loss-of-function experiments in Foxa1-modified cells demonstrated that the activities of NKA were dependent on the presence of Foxa1. Collectively, these data provided evidence that Foxa1 may influence ESG development through transcriptional regulation of NKA expression.

Late testing and antiretroviral therapy (ART) prevailed among people living with HIV (PLHIV) and impacted the benefit of immediate ART. This study aimed to identify the benefit of the test-and-immediate-treat policy in China, the effect of immediate ART, and the influence of late testing and ART on the whole PLHIV in Guangdong Province, China. We designed two tendency analyses in aggregative form and two cohorts (surveillance and ART cohort) in individuals' perspectives based on the HIV/AIDS Comprehensive Response Information Management System. Two interrupted time series models were conducted for tendency analysis from 2009 to 2018 to explore the all-cause and short-term mortality decrease after the test-and-immediate-treat policy. A time-dependent Cox model was performed for the surveillance cohort from 1992 to 2018 and a joint model was utilized for the ART cohort to identify the effect of immediate ART and the influence of late testing and ART on death. The tendency analysis included 324,914 and 68,679 person-year for all-cause/short-term mortality. A total of 49,289 and 26,287 PLHIV were recruited in the surveillance and ART cohort with 5,557 and 459 deaths, respectively. The short-term mortality dropped from 4.69 cases/100 person-year in January 2009 to 0.35 cases/100 person-year in December 2018 (standardized rate). The all-cause mortality saw a decreasing trend from 1.46 cases/100 person-year in January 2009 to 0.14 cases/100 person-year in December 2018 (standardized rate). The tendency analysis showed a significant short-term mortality slope decrease after the test-and-immediate-treat policy (P = 0.024). From the surveillance cohort, late testing, in general, was a risk factor for all-cause mortality [hazard ratio (HR) = 1.330, 95% CI, 1.250, 1.416]. ART cohort showed higher hazards of all-cause mortality among PLHIV with no late testing, but late ART (HR = 1.690, 95% CI, 1.166, 2.451) and both the late testing and late ART (HR = 1.335, 95% CI, 1.042, 1.710). Immediate ART might decrease the hazard of all-cause death though it is insignificant (HR = 0.923, 95% CI: 0.755, 1.129) in the ART cohort. The test-and-immediate-test policy brought benefit to PLHIV. We should enlarge HIV testing using comprehensive approaches to decrease late testing and ART and increase the benefit of immediate ART.

Psoriasis is a common chronic immune-inflammatory disease. Challenges exist in the present treatment of psoriasis, such as difficulties in transdermal drug administration and severe side effects. We hope to achieve a better therapeutic outcome for psoriasis treatment. By using modified soluble microneedles (MNs) loaded with daphnetin, the psoriasis symptoms of mice, the abnormal proliferation of keratinocytes, and the secretion of inflammatory factors were significantly reduced. In vitro, daphnetin is proven to inhibit the NF-κB signaling pathway and to inhibit the proliferation of HaCaT cells and the release of inflammatory factors, especially CCL20. This research showed that the modified microneedle loaded with daphnetin optimized transdermal drug delivery and relieved the symptoms of psoriasis more effectively. The novel route of Daph administration provides a future research direction for the treatment of psoriasis.

An amendment to this paper has been published and can be accessed via the original article.

Abstract The hair follicle (HF) is a highly conserved sensory organ associated with the immune response against pathogens, thermoregulation, sebum production, angiogenesis, neurogenesis and wound healing. Although recent advances in lineage-tracing techniques and the ability to profile gene expression in small populations of cells have increased the understanding of how stem cells operate during hair growth and regeneration, the construction of functional follicles with cycling activity is still a great challenge for the hair research field and for translational and clinical applications. Given that hair formation and cycling rely on tightly coordinated epithelial–mesenchymal interactions, we thus review potential cell sources with HF-inducive capacities and summarize current bioengineering strategies for HF regeneration with functional restoration.

3-dimensional (3D) bioprinting technology provides promising strategy in the fabrication of artificial tissues and organs. As the fundamental element in bioprinting process, preparation of bioink with ideal mechanical properties without sacrifice of biocompatibility is a great challenge. In this study, a supramolecular hydrogel-based bioink is prepared by polyethylene glycol (PEG) grafted chitosan, α-cyclodextrin (α-CD) and gelatin. It has a primary crosslinking structure through the aggregation of the pseudo-polyrotaxane-like side chains, which are formed from the host-guest interactions between α-CD and PEG side chain. Apparent viscosity measurement shows the shear-shinning property of this bioink, which might be due to the reversibility of the physical crosslinking. Moreover, with β-glycerophosphate at different concentrations as the secondary crosslinking agent, the printed constructs demonstrate different Young's modulus (p

Abstract Background Fibroblasts are crucial for supporting normal wound healing. However, the functional state of these cells is impaired in diabetics because of a high-glucose (HG) microenvironment. Small extracellular vesicles (sEVs) have emerged as a promising tool for skin wound treatment. The aim of this study was to investigate the effects of sEVs derived from human decidua-derived mesenchymal stem cells (dMSC-sEVs) on HG-induced human dermal fibroblast (HDF) senescence and diabetic wound healing and explore the underlying mechanism. Methods We first created a HDF senescent model induced by HG in vitro. dMSC-conditioned medium (dMSC-CM) and dMSC-sEVs were collected and applied to treat the HG-induced HDFs. We then examined the proliferation, migration, differentiation, and senescence of these fibroblasts. At the same time, the expressions of RAGE, p21 RAS, Smad2/3, and pSmad2/3 were also analyzed. Furthermore, pSmad2/3 inhibitor (SB431542) was used to block the expression of pSmad2/3 to determine whether dMSC-sEVs improved HDF senescence by activating Smad pathway. Finally, we assessed the effect of dMSC-sEVs on diabetic wound healing. Results The HG microenvironment impaired the proliferation, migration, and differentiation abilities of the HDFs and accelerated their senescence. dMSC-CM containing sEVs improved the proliferation and migration abilities of the HG-induced fibroblasts. dMSC-sEVs internalized by HG-induced HDFs not only significantly promoted HDF proliferation, migration, and differentiation, but also improved the senescent state. Furthermore, dMSC-sEVs inhibited the expression of RAGE and stimulated the activation of Smad signaling pathway in these cells. However, SB431542 (pSmad2/3 inhibitor) could partially alleviate the anti-senescent effects of dMSC-sEVs on HG-induced HDFs. Moreover, the local application of dMSC-sEVs accelerated collagen deposition and led to enhanced wound healing in diabetic mice. The detection of PCNA, CXCR4, α-SMA, and p21 showed that dMSC-sEVs could enhance HDF proliferation, migration, and differentiation abilities and improve HDF senescent state in vivo. Conclusion dMSC-sEVs have regenerative and protective effects on HG-induced senescent fibroblasts by suppressing RAGE pathway and activating Smad pathway, thereby accelerating diabetic wound healing. This indicates that dMSC-sEVs may be a promising candidate for diabetic wound treatment.

Abstract Restoration of sweat glands (SwGs) represents a great issue in patients with extensive skin defects. Recent methods combining organoid technology with cell fate reprogramming hold promise for developing new regenerative methods for SwG regeneration. Here, a practical strategy for engineering functional human SwGs in vitro and in vivo is provided. First, by forced expression of the ectodysplasin‐A in human epidermal keratinocytes (HEKs) combined with specific SwG culture medium, HEKs are efficiently converted into SwG cells (iSwGCs). The iSwGCs show typical morphology, gene expression pattern, and functions resembling human primary SwG cells. Second, by culturing the iSwGCs in a special 3D culturing system, SwG organoids (iSwGOs) that exhibit structural and biological features characteristic of native SwGs are obtained. Finally, these iSwGOs are successfully transplanted into a mouse skin damage model and they develop into fully functioning SwGs in vivo. Regeneration of functional SwG organoids from reprogrammed HEKs highlights the great translational potential for personalized SwG regeneration in patients with large skin defects.

Persistent hyper-inflammation is a distinguishing pathophysiological characteristic of chronic wounds, and macrophage malfunction is considered as a major contributor thereof. In this review, we describe the origin and heterogeneity of macrophages during wound healing, and compare macrophage function in healing and non-healing wounds. We consider extrinsic and intrinsic factors driving wound macrophage dysregulation, and review systemic and topical therapeutic approaches for the restoration of macrophage response. Multidimensional analysis is highlighted through the integration of various high-throughput technologies, used to assess the diversity and activation states as well as cellular communication of macrophages in healing and non-healing wound. This research fills the gaps in current literature and provides the promising therapeutic interventions for chronic wounds.

Abstract Background Mammary progenitor cells (MPCs) maintain their reproductive potency through life, and their specific microenvironments exert a deterministic control over these cells. MPCs provides one kind of ideal tools for studying engineered microenvironmental influence because of its accessibility and continually undergoes postnatal developmental changes. The aim of our study is to explore the critical role of the engineered sweat gland (SG) microenvironment in reprogramming MPCs into functional SG cells. Methods We have utilized a three-dimensional (3D) SG microenvironment composed of gelatin-alginate hydrogels and components from mouse SG extracellular matrix (SG-ECM) proteins to reroute the differentiation of MPCs to study the functions of this microenvironment. MPCs were encapsulated into the artificial SG microenvironment and were printed into a 3D cell-laden construct. The expression of specific markers at the protein and gene levels was detected after cultured 14 days. Results Compared with the control group, immunofluorescence and gene expression assay demonstrated that MPCs encapsulated in the bioprinted 3D-SG microenvironment could significantly express the functional marker of mouse SG, sodium/potassium channel protein ATP1a1, and tend to express the specific marker of luminal epithelial cells, keratin-8. When the Shh pathway is inhibited, the expression of SG-associated proteins in MPCs under the same induction environment is significantly reduced. Conclusions Our evidence proved the ability of differentiated mouse MPCs to regenerate SG cells by engineered SG microenvironment in vitro and Shh pathway was found to be correlated with the changes in the differentiation. These results provide insights into regeneration of damaged SG by MPCs and the role of the engineered microenvironment in reprogramming cell fate.

Radiation damage causes DNA foci to form and senescence, causing ulcers. Here, the authors show that a naturally occurring adenosine analogue, cordycepin, prevents cell senescence via an increase in AMPK/NRF2, so blocking ulcers caused by radiation on skin/intestine/tongue damage in rodents.

Abstract Ischemic diseases, which are caused by a reduction of blood supply that results in reduced oxygen transfer and nutrient uptake, are becoming the leading cause of disabilities and deaths. Therapeutic angiogenesis is key for the treatment of these diseases. Stem cells have been used in animal models and clinical trials to treat various ischemic diseases. Recently, the efficacy of stem cell therapy has increasingly been attributed to exocrine functions, particularly extracellular vesicles. Extracellular vesicles are thought to act as intercellular communication vehicles to transport informational molecules including proteins, mRNA, microRNAs, DNA fragments, and lipids. Studies have demonstrated that extracellular vesicles promote angiogenesis in cellular experiments and animal models. Herein, recent reports on the use of extracellular vesicles for therapeutic angiogenesis during ischemic diseases are presented and discussed. We believe that extracellular vesicles-based therapeutics will be an ideal treatment method for patients with ischemic diseases.

Abstract Iatrogenic wounds are a common but often overlooked concept. They can lead to increases in hospital stays, therapy costs, repeat surgeries, and implant removal. If not handled properly, these wounds have a very poor prognosis and will cause serious physical and psychological harm to patients, which may result in medicolegal disputes. In recent years, the incidence of iatrogenic wounds has increased because of (1) an increase in the population of older people owing to increased life expectancy, (2) the continued expansion of surgical indications, (3) an increase in difficult surgeries, and (4) the constant emergence and application of new implantable biomaterials and other therapies. Thus, there is a pressing clinical need to improve the therapy of iatrogenic wounds. However, the difficulty in treating these wounds is considerable due to the emergence of drug-resistant bacteria, the high number of patients with metabolic diseases, and complex complications in patients. In particular, iatrogenic wounds caused by surgical site infections due to implantable biomaterials could lead to material leakage and conflicts regarding whether to retain or remove the implants. This review provides a definition of iatrogenic wounds, describes their characteristics, classifies them, and provides information about the importance of analyzing iatrogenic wounds. We hope that this review will provide useful information for the diagnosis and treatment of iatrogenic wounds and help to reduce their incidence in the future.

Abstract Background Guangdong Province is one of the most developed and populous provinces in southern China, with frequent foreign exchanges and large transient population. The annual number of cases of HIV/AIDS reported in Guangdong has been higher than most of provinces in China for several successive years. HIV infection by heterosexual transmission occurs across the province, with transmission among men who have sex with men occurring mainly in larger urban centers. There is a lack of widespread and representative data on the distribution of HIV subtypes in Guangdong. This study aimed to thoroughly investigate and estimate the prevalence and distribution of HIV-1 subtypes using a city-based sampling strategy to better understand the characteristics of HIV transmission in Guangdong. Methods Archived plasma samples (n = 1205) from individuals diagnosed as HIV-1 infection in 2013 were selected randomly from all 21 cities in Guangdong Province. Genotypes were determined using env and/or gag sequences using phylogenetic analysis. The distributions of HIV genotypes in different risk groups and different cities were analyzed. Results A total of 15 genotypes, including six discordant genotypes, were identified. The four main HIV-1 subtypes in Guangdong were CRF01_AE (43.2%), CRF07_BC (26.3%), CRF55_01B (8.5%), and CRF08_BC (8.4%). CRF01_AE was the predominant subtype in all risk populations. The high mobility of people shaped the complexity of the HIV genotypes, while the switch of risk factors affected the distribution and future trend of HIV-1 genotypes in Guangdong. Another epicenter located in the western region in addition to the known epicenter cities in the Pearl River Delta region of Guangdong may exist. Conclusions Our study provides a comprehensive molecular epidemiologic dataset to understand the diversity and distribution of HIV genotypes in Guangdong, as well as to clarify the unique region- and risk group-specific transmission dynamics. The results provide critical and insightful information for more effective intervention strategies to limit HIV transmission in the future.

Wound healing is a multi-step process that includes multiple cellular events such as cell proliferation, cell adhesion, and chemotactic response as well as cell apoptosis. Accumulating studies have documented the significance of stromal cell-derived factor-1 (SDF-1)/C-X-C chemokine receptor 4 (CXCR4) signaling in wound repair and regeneration. However, the molecular mechanism of regeneration is not clear. This review describes various types of tissue regeneration that CXCR4 participates in and how the efficiency of regeneration is increased by CXCR4 overexpression. It emphasizes the pleiotropic effects of CXCR4 in regeneration. By delving into the specific molecular mechanisms of CXCR4, we hope to provide a theoretical basis for tissue engineering and future regenerative medicine.

Mesenchymal stem cells (MSCs) have been widely used in the fields of tissue engineering and regenerative medicine due to their self-renewal capabilities and multipotential differentiation assurance. However, capitalizing on specific factors to precisely guide MSC behaviors is the cornerstone of biomedical applications. Fortunately, several key biophysical and biochemical cues of biomaterials that can synergistically regulate cell behavior have paved the way for the development of cell-instructive biomaterials that serve as delivery vehicles for promoting MSC application prospects. Therefore, the identification of these cues in guiding MSC behavior, including cell migration, proliferation, and differentiation, may be of particular importance for better clinical performance. This review focuses on providing a comprehensive and systematic understanding of biophysical and biochemical cues, as well as the strategic engineering of these signals in current scaffold designs, and we believe that integrating biophysical and biochemical cues in next-generation biomaterials would potentially help functionally regulate MSCs for diverse applications in regenerative medicine and cell therapy in the future.

Neurological syndromes are observed in numerous patients who suffer burns, which add to the economic burden of societies and families. Recent studies have implied that blood–brain barrier (BBB) dysfunction is the key factor that induces these central nervous system (CNS) syndromes in peripheral traumatic disease, e.g., surgery and burns. However, the effect of burns on BBB and the underlying mechanism remains, largely, to be determined. The present study aimed to investigate the effect of burns on BBB and the potential of umbilical cord-derived mesenchymal stem cells (UC-MSCs), which have strong anti-inflammatory and repairing ability, to protect the integrity of BBB. BBB permeability was evaluated using dextran tracer (immunohistochemistry imaging and spectrophotometric quantification) and western blot, interleukin (IL)-6, and IL-1β levels in blood and brain were measured by enzyme-linked immunosorbent assay. Furthermore, transmission electron microscopy (TEM) was used to detect transcellular vesicular transport (transcytosis) in BBB. We found that burns increased mouse BBB permeability to both 10-kDa and 70-kDa dextran. IL-6 and IL-1β levels increased in peripheral blood and CNS after burns. In addition, burns decreased the level of tight junction proteins (TJs), including claudin-5, occludin, and ZO-1, which indicated increased BBB permeability due to paracellular pathway. Moreover, increased vesicular density after burns suggested increased transcytosis in brain microvascular endothelial cells. Finally, administering UC-MSCs at 1 h after burns effectively reversed these adverse effects and protected the integrity of BBB. These results suggest that burns increase BBB permeability through both paracellular pathway and transcytosis, the potential mechanism of which might be through increasing IL-6 and IL-1β levels and decreasing Mfsd2a level, and appropriate treatment with UC-MSCs can reverse these effects and protect the integrity of BBB after burns.

Abstract Background Damaged or malfunctioning sweat glands (SGs) after a burn injury would cause significant hyperthermia and even death, and there is an unmet need for effective treatment. Genetically reprogrammed stem cells show their potential advantages for inducing SG repair and regeneration. Methods The expression of interferon regulatory factor 6 (IRF6) in skin was tested by immunofluorescence, and Irf6 was overexpressed in epidermal progenitors (EPs) to stimulate SG differentiation. For in-vivo studies, second- and third-degree mouse burn wounds were treated with subcutaneous injection of EPs and Irf6-transfected cells, and cell retention and therapeutic effects were assessed. Results IRF6 demonstrated differential expression between the footpad and dorsal skin and was upregulated along with embryonic and postnatal SG development. The Irf6-transfected cells converted their cell phenotypes as seen by gene and protein expression analyses and their morphology closely resembled epidermal-derived glandular cells. Inductive SG cell (SGC) transplantation and in-vivo tracing examination demonstrated that they could survive at damaged sites for 14 days. In comparison, the positive effects of inductive SGCs only result in restoring SG function in second-degree burn wounds but not in third-degree burn wounds as assessed by both perspiration tests and morphological analyses. Conclusions These results suggest that IRF6 plays an important role in directing glandular lineage differentiation of Eps, but that the therapeutic efficacy of inductive SGCs may be restricted to the burn environment.

Abstract Background Patients with a deep burn injury are characterized by losing the function of perspiration and being unable to regenerate the sweat glands. Because of their easy accession, multipotency, and lower immunogenicity, bone marrow-derived mesenchymal stem cells (BM-MSCs) represent as an ideal biological source for cell therapy. The aim of this study was to identify whether targeting the promotor of ectodysplasin (EDA) by CRISPR/dCas9-effector (dCas9-E) could induce the BM-MSCs to differentiate into sweat gland-like cells (SGCs). Methods Activation of EDA transcription in BM-MSCs was attained by transfection of naive BM-MSCs with the lenti-CRISPR/dCas9-effector and single-guide RNAs (sgRNAs). The impact of dCas9-E BM-MSCs on the formation of SGCs and repair of burn injury was identified and evaluated both in vitro and in a mouse model. Results After transfection with sgRNA-guided dCas9-E, the BM-MSCs acquired significantly higher transcription and expression of EDA by doxycycline (Dox) induction. Intriguingly, the specific markers (CEA, CK7, CK14, and CK19) of sweat glands were also positive in the transfected BM-MSCs, suggesting that EDA plays a critical role in promoting BM-MSC differentiation into sweat glands. Furthermore, when the dCas9-E BM-MSCs with Dox induction were implanted into a wound in a laboratory animal model, iodine-starch perspiration tests revealed that the treated paws were positive for perspiration, while the paws treated with saline showed a negative manifestation. For the regulatory mechanism, the expression of downstream genes of NF-κB (Shh and cyclin D1) was also enhanced accordingly. Conclusions These results suggest that EDA is a pivotal factor for sweat gland regeneration from BM-MSCs and may also offer a new approach for destroyed sweat glands and extensive deep burns.