Endothelial progenitor cells and a stromal cell-derived factor-1α analogue synergistically improve survival in sepsis

hnRNPA2B1 promotes the production of exosomal miR-103-3p from endothelial progenitor cells to alleviate macrophage M1 polarization in acute respiratory distress syndrome

BACKGROUND

Macrophage polarization plays a crucial role in acute respiratory distress syndrome (ARDS). Recently, mounting evidence has uncovered that endothelial progenitor cells (EPCs) secreted exosomes (EPCs-Exos) exert obvious therapeutic effects on the pathological inflammatory process of ARDS, but its potential mechanism is rarely reported.

METHODS

The primary mouse EPCs and EPCs-Exos were isolated and identified. Absorption of EPCs-Exos by RAW264.7 cells was examined by PKH-26 staining. The polarization of RAW264.7 cells was evaluated by flow cytometry and RT-qPCR analysis. Molecular interactions were verified by dual luciferase assay, RNA pull-down and RNA immunocoprecipitation assays. ARDS mouse model was established, and pathological changes and expressions of related molecules were detected by HE staining, RT-qPCR and western blotting.

RESULTS

EPCs-Exos could be transferred to macrophages, and effectively reversed LPS-induced polarization of macrophages from M2 to M1 phenotype; however, these changes were diminished by activation of TLR4/NF-κB pathway. MiR-103-3p was proved to be enriched in EPC-Exos and could transfer to macrophage and inactivating TLR4/NF-κB pathway via directly binding to TLR4 3'-UTR. Moreover, miR-103-3p overexpression elevated macrophage M2 polarization and repressed M1 polarization in LPS-treated cells by inhibiting TLR4/NF-κB pathway, and knockdown of miR-103-3p in EPC-Exos abolished the regulatory roles of EPC-Exos on macrophage polarization in vitro, and lung inflammatory injury in vivo. HnRNPA2B1 was proved to interact with miR-103-3p and responsible for its exosomal secretion, which repressed pro-inflammatory macrophage polarization.

CONCLUSION

These findings suggested that hnRNPA2B1-mediated exosomal delivery of miR-103-3p from EPCs protected against macrophage inflammation in ARDS by inactivation of TLR4/NF-κB pathway.

Exosome-Derived microRNA: Potential Target for Diagnosis and Treatment of Sepsis

Exosome-derived microRNAs (miRNAs) are emerging as pivotal players in the pathophysiology of sepsis, representing a new frontier in both the diagnosis and treatment of this complex condition. Sepsis, a severe systemic response to infection, involves intricate immune and nonimmune mechanisms, where exosome-mediated communication can significantly influence disease progression and outcomes. During the progress of sepsis, the miRNA profile of exosomes undergoes notable alterations, is reflecting, and may affect the progression of the disease. This review comprehensively explores the biology of exosome-derived miRNAs, which originate from both immune cells (such as macrophages and dendritic cells) and nonimmune cells (such as endothelial and epithelial cells) and play a dynamic role in modulating pathways that affect the course of sepsis, including those related to inflammation, immune response, cell survival, and apoptosis. Taking into account these dynamic changes, we further discuss the potential of exosome-derived miRNAs as biomarkers for the early detection and prognosis of sepsis and advantages over traditional biomarkers due to their stability and specificity. Furthermore, this review evaluates exosome-based therapeutic miRNA delivery systems in sepsis, which may pave the way for targeted modulation of the septic response and personalized treatment options.

Nucleic acid-based nanotherapeutics for treating sepsis and associated organ injuries

In recent years, gene therapy has been made possible with the success of nucleic acid drugs against sepsis and its related organ dysfunction. Therapeutics based on nucleic acids such as small interfering RNAs (siRNAs), microRNAs (miRNAs), messenger RNAs (mRNAs), and plasmid DNAs (pDNAs) guarantee to treat previously undruggable diseases. The advantage of nucleic acid-based therapy against sepsis lies in the development of nanocarriers, achieving targeted and controlled gene delivery for improved efficacy with minimal adverse effects. Entrapment into nanocarriers also ameliorates the poor cellular uptake of naked nucleic acids. In this study, we discuss the current state of the art in nanoparticles for nucleic acid delivery to treat hyperinflammation and apoptosis associated with sepsis. The optimized design of the nanoparticles through physicochemical property modification and ligand conjugation can target specific organs-such as lung, heart, kidney, and liver-to mitigate multiple sepsis-associated organ injuries. This review highlights the nanomaterials designed for fabricating the anti-sepsis nanosystems, their physicochemical characterization, the mechanisms of nucleic acid-based therapy in working against sepsis, and the potential for promoting the therapeutic efficiency of the nucleic acids. The current investigations associated with nanoparticulate nucleic acid application in sepsis management are summarized in this paper. Noteworthily, the potential application of nanotherapeutic nucleic acids allows for a novel strategy to treat sepsis. Further clinical studies are required to confirm the findings in cell- and animal-based experiments. The capability of large-scale production and reproducibility of nanoparticle products are also critical for commercialization. It is expected that numerous anti-sepsis possibilities will be investigated for nucleic acid-based nanotherapeutics in the future.

Lung regeneration: diverse cell types and the therapeutic potential

Lung tissue has a certain regenerative ability and triggers repair procedures after injury. Under controllable conditions, lung tissue can restore normal structure and function. Disruptions in this process can lead to respiratory system failure and even death, causing substantial medical burden. The main types of respiratory diseases are chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and acute respiratory distress syndrome (ARDS). Multiple cells, such as lung epithelial cells, endothelial cells, fibroblasts, and immune cells, are involved in regulating the repair process after lung injury. Although the mechanism that regulates the process of lung repair has not been fully elucidated, clinical trials targeting different cells and signaling pathways have achieved some therapeutic effects in different respiratory diseases. In this review, we provide an overview of the cell type involved in the process of lung regeneration and repair, research models, and summarize molecular mechanisms involved in the regulation of lung regeneration and fibrosis. Moreover, we discuss the current clinical trials of stem cell therapy and pharmacological strategies for COPD, IPF, and ARDS treatment. This review provides a reference for further research on the molecular and cellular mechanisms of lung regeneration, drug development, and clinical trials.

Evolutionary trend analysis and knowledge structure mapping of endothelial dysfunction in sepsis: a bibliometrics study

BACKGROUND

A pathophysiological feature of septic organ failure is endothelial dysfunction in sepsis (EDS). The physiological and pathological mechanism of sepsis is considered to be vascular leakage caused by endothelial dysfunction. These pathological changes lead to systemic organ injury. However, an analysis using bibliometric methods has not yet been conducted in the field of EDS. This study was conducted to provide an overview of knowledge structure and research trends in the field of EDS.

METHODS

Based on previous research, a literature search was performed in the Web of Science Core Collection (WoSCC) for publications associated with EDS published between the year 2003 and 2023. Various types of data from the publications, such as citation frequency, authorship, keywords and highly cited articles, were extracted. The "Create Citation Report" feature in the WoSCC was employed to calculate the Hirsch index (h-index) and average citations per item (ACI) of authors, institutions, and countries. To conduct bibliometric and visualization analyses, three bibliometric tools were used, including R-bibliometrix, CiteSpace (co-citation analysis of references), and VOSviewer (co-authorship analysis of institutions, co-authorship analysis of authors, co-occurrence analysis of keywords).

RESULTS

After excluding invalid records, the study finaly included 4,536 publications with 135,386 citations. Most of these publications originated in the USA, China, Germany, Canada, and Japan. Harvard University emerged as the most prolific institution, while professor Jong-Sup Bae and his research team at Kyungpook National University emerged as authors with the greatest influence. The "protein C", "tissue factor", "thrombin", "glycocalyx", "acute kidney injury", "syndecan-1" and "biomarker" were identified as prominent areas of research. Future research may focus on molecular mechanisms (such as as vascular endothelial [VE]-cadherin regulation) and therapeutic interventions to enhance endothelial repair and function.

CONCLUSION

Our findings show a growing interest in EDS research. Key areas for future research include signaling pathways, molecular mechanisms, endothelial repair, and interactions between endothelial cells and other cell types in sepsis.

Endothelial-Related Biomarkers in Evaluation of Vascular Function During Progression of Sepsis After Severe Trauma: New Potential Diagnostic Tools in Sepsis

Purpose

This study aimed to investigate the changes in endothelial-related biomarkers and their relationship with the incidence and prognosis of patients with sepsis after severe trauma.

Methods

A total of 37 severe trauma patients admitted to our hospital from Jan. to Dec. 2020 were enrolled in our research. All enrolled patients were divided into the sepsis and the non-sepsis groups. Endothelial progenitor cells (EPCs), circulating endothelial cells (CECs), and endothelial microparticles (EMPs) were detected on admission time; 24-48 hours and 48-72 hours after admission respectively. Demographic data, Acute Physiology, Chronic Health Evaluation (APACHE) II, and Sequential Organ Failure Assessment (SOFA) score were calculated every 24 h of admission to assess the severity of organ dysfunction. Receiver operating characteristic (ROC) curves were drawn to compare the areas under the curve (AUC) of endothelial-related biomarkers for the diagnosis of sepsis.

Results

The incidence rate of sepsis was 45.95% in all patients. The SOFA score in the sepsis group was significantly higher than that in the non-sepsis group (2 points vs 0 points, P<0.01). The number of EPCs, CECs, and EMPs all rose quickly in the early phase after trauma. The number of EPCs was similar in both groups, but the number of CECs and EMPs in the Sepsis Group was much higher than in the non-Sepsis Group (all P<0.01). Logistic regression analysis showed that the occurrence of sepsis was closely related to the expression of 0-24h CECs and 0-24h EMPs. The AUC ROC for CECs in different time periods were 0.815, 0.877, and 0.882, respectively (all P<0.001). The AUC ROC for EMPs in 0-24h was 0.868 (P=0.005).

Conclusion

The expression of EMPs was higher in early severe trauma, and high levels of EMPs were significantly higher in patients with early sepsis and poor prognosis.

Role of Extracellular microRNAs in Sepsis-Induced Acute Lung Injury

Acute lung injury (ALI) is a life-threatening pathological disease characterized by the damage of pulmonary endothelial cells and epithelial cell barriers by uncontrolled inflammation. During sepsis-induced ALI, multiple cells cooperate and communicate with each other to respond to the stimulation of inflammatory factors. However, the underlying mechanisms of action have not been fully identified, and the modes of communication therein are also being investigated. Extracellular vesicles (EVs) are a heterogeneous population of spherical membrane structures released by almost all types of cells, containing various cellular components. EVs are primary transport vehicles for microRNAs (miRNAs), which play essential roles in physiological and pathological processes in ALI. EV miRNAs from different sources participated in regulating the biological function of pulmonary epithelial cells, endothelial cells, and phagocytes by transferring miRNA through EVs during ALI induced by sepsis, which has great potential diagnostic and therapeutic values. This study aims to summarize the role and mechanism of extracellular vesicle miRNAs from different cells in the regulation of sepsis-induced ALI. It provides ideas for further exploring the role of extracellular miRNA secreted by different cells in the ALI induced by sepsis, to make up for the deficiency of current understanding, and to explore the more optimal scheme for diagnosis and treatment of ALI.

Alarmins and MicroRNAs, a New Axis in the Genesis of Respiratory Diseases: Possible Therapeutic Implications

It is well ascertained that airway inflammation has a key role in the genesis of numerous respiratory pathologies, including asthma, chronic obstructive pulmonary disease, and acute respiratory distress syndrome. Pulmonary tissue inflammation and anti-inflammatory responses implicate an intricate relationship between local and infiltrating immune cells and structural pulmonary cells. Alarmins are endogenic proteins discharged after cell injury in the extracellular microenvironment. The purpose of our review is to highlight the alterations in respiratory diseases involving some alarmins, such as high mobility group box 1 (HMGB1) and interleukin (IL)-33, and their inter-relationships and relationships with genetic non-coding material, such as microRNAs. The role played by these alarmins in some pathophysiological processes confirms the existence of an axis composed of HMGB1 and IL-33. These alarmins have been implicated in ferroptosis, the onset of type 2 inflammation and airway alterations. Moreover, both factors can act on non-coding genetic material capable of modifying respiratory function. Finally, we present an outline of alarmins and RNA-based therapeutics that have been proposed to treat respiratory pathologies.

Endothelial progenitor cells in the host defense response

Extensive injury of endothelial cells in blood vasculature, especially in the microcirculatory system, frequently occurs in hosts suffering from sepsis and the accompanied systemic inflammation. Pathological factors, including toxic components derived from invading microbes, oxidative stress associated with tissue ischemia/reperfusion, and vessel active mediators generated during the inflammatory response, are known to play important roles in mediating endothelial injury. Collapse of microcirculation and tissue edema developed from the failure of endothelial barrier function in vital organ systems, including the lung, brain, and kidney, are detrimental, which often predict fatal outcomes. The host body possesses a substantial capacity for maintaining vascular homeostasis and repairing endothelial damage. Bone marrow and vascular wall niches house endothelial progenitor cells (EPCs). In response to septic challenges, EPCs in their niche environment are rapidly activated for proliferation and angiogenic differentiation. In the meantime, release of EPCs from their niches into the blood stream and homing of these vascular precursors to tissue sites of injury are markedly increased. The recruited EPCs actively participate in host defense against endothelial injury and repair of damage in blood vasculature via direct differentiation into endothelial cells for re-endothelialization as well as production of vessel active mediators to exert paracrine and autocrine effects on angiogenesis/vasculogenesis. In recent years, investigations on significance of EPCs in host defense and molecular signaling mechanisms underlying regulation of the EPC response have achieved substantial progress, which promotes exploration of vascular precursor cell-based approaches for effective prevention and treatment of sepsis-induced vascular injury as well as vital organ system failure.

CD34 positive cells as endothelial progenitor cells in biology and medicine

CD34 is a cell surface antigen expressed in numerous stem/progenitor cells including hematopoietic stem cells (HSCs) and endothelial progenitor cells (EPCs), which are known to be rich sources of EPCs. Therefore, regenerative therapy using CD34⁺ cells has attracted interest for application in patients with various vascular, ischemic, and inflammatory diseases. CD34⁺ cells have recently been reported to improve therapeutic angiogenesis in a variety of diseases. Mechanistically, CD34⁺ cells are involved in both direct incorporation into the expanding vasculature and paracrine activity through angiogenesis, anti-inflammatory, immunomodulatory, and anti-apoptosis/fibrosis roles, which support the developing microvasculature. Preclinical, pilot, and clinical trials have well documented a track record of safety, practicality, and validity of CD34⁺ cell therapy in various diseases. However, the clinical application of CD34⁺ cell therapy has triggered scientific debates and controversies in last decade. This review covers all preexisting scientific literature and prepares an overview of the comprehensive biology of CD34⁺ cells as well as the preclinical/clinical details of CD34⁺ cell therapy for regenerative medicine.

Extracellular vesicles participate in the pathogenesis of sepsis

Sepsis is one of the leading causes of mortality worldwide and is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. The early diagnosis and effective treatment of sepsis still face challenges due to its rapid progression, dynamic changes, and strong heterogeneity among different individuals. To develop novel strategies to control sepsis, a better understanding of the complex mechanisms of sepsis is vital. Extracellular vesicles (EVs) are membrane vesicles released from cells through different mechanisms. In the disease state, the number of EVs produced by activated or apoptotic cells and the cargoes they carry were altered. They regulated the function of local or distant host cells in autocrine or paracrine ways. Current studies have found that EVs are involved in the occurrence and development of sepsis through multiple pathways. In this review, we focus on changes in the cargoes of EVs in sepsis, the regulatory roles of EVs derived from host cells and bacteria, and how EVs are involved in multiple pathological processes and organ dysfunction in sepsis. Overall, EVs have great application prospects in sepsis, such as early diagnosis of sepsis, dynamic monitoring of disease, precise therapeutic targets, and prevention of sepsis as a vaccine platform.

Protective effect of endothelial progenitor cell-derived exosomal microRNA-382-3p on sepsis-induced organ damage and immune suppression in mice

OBJECTIVE

To explore the role of endothelial progenitor cell (EPC)-derived exosomal microRNA-382-3p (miR-382-3p) in septic injury in mice.

METHODS

A murine model of sepsis was introduced by cecal ligation and puncture (CLP). The model mice were treated with EPC-derived exosomes (Exos). The lung, kidney and liver tissues of mice were collected and stained with hematoxylin and eosin. The lymphocytes in murine spleen tissues, and the proportion and phenotype of the T helper cells (Ths) were examined by flow cytometry. The exosomal miRNAs were screened using a microarray analysis. The expressions of miR-382-3p and beta-transducin repeat containing E3 ubiquitin protein ligase (BTRC) were measured to explore possible mechanism of Exos in septic injury in mice.

RESULTS

EPC-derived Exos alleviated CLP-induced tissue damage in the lung, kidney and liver tissues in septic mice. They also restored the number of lymphocytes and the concentration of Ths, and reduced the imbalance in Th1 and Th2 cells in mice. The Exos mainly contained miR-382-3p, and miR-382-3p directly targeted BTRC mRNA. Either downregulation of miR-382-3p or upregulation of BTRC blocked the protective roles of Exos in septic injury and immune suppression. Overexpression of BTRC increased the phosphorylation of nuclear factor kappa B (NF-κB) inhibitor α (IκBα) and NF-κB.

CONCLUSION

EPC-derived exosomal miR-382-3p alleviates sepsis-induced organ damage and immune suppression in septic mice through regulating BTRC and the IκBα/NF-κB axis.

Comprehensive insight into endothelial progenitor cell-derived extracellular vesicles as a promising candidate for disease treatment

Endothelial progenitor cells (EPCs), which are a type of stem cell, have been found to have strong angiogenic and tissue repair capabilities. Extracellular vesicles (EVs) contain many effective components, such as cellular proteins, microRNAs, messenger RNAs, and long noncoding RNAs, and can be secreted by different cell types. The functions of EVs depend mainly on their parent cells. Many researchers have conducted functional studies of EPC-derived EVs (EPC-EVs) and showed that they exhibit therapeutic effects on many diseases, such as cardiovascular disease, acute kidney injury, acute lung injury, and sepsis. In this review article, we comprehensively summarized the biogenesis and functions of EPCs and EVs and the potent role of EPC-EVs in the treatment of various diseases. Furthermore, the current problems and future prospects have been discussed, and further studies are needed to compare the therapeutic effects of EVs derived from various stem cells, which will contribute to the accelerated translation of these applications in a clinical setting.

Hydrogen Repairs LPS-Induced Endothelial Progenitor Cells Injury via PI3K/AKT/eNOS Pathway

Endotoxins and other harmful substances may cause an increase in permeability in endothelial cells (ECs) monolayers, as well as ECs shrinkage and death to induce lung damage. Lipopolysaccharide (LPS) can impair endothelial progenitor cells (EPCs) functions, including proliferation, migration, and tube formation. EPCs can migrate to the damaged area, differentiate into ECs, and participate in vascular repair, which improves pulmonary capillary endothelial dysfunction and maintains the integrity of the endothelial barrier. Hydrogen (H2) contributes to the repairment of lung injury and the damage of ECs. We therefore speculate that H2 protects the EPCs against LPS-induced damage, and it's mechanism will be explored. The bone marrow-derived EPCs from ICR Mice were treated with LPS to establish a damaged model. Then EPCs were incubated with H2, and treated with PI3K inhibitor LY294002 and endothelial nitric oxide synthase (eNOS) inhibitor L-NAME. MTT assay, transwell assay and tube formation assay were used to detect the proliferation, migration and angiogenesis of EPCs. The expression levels of target proteins were detected by Western blot. Results found that H2 repaired EPCs proliferation, migration and tube formation functions damaged by LPS. LY294002 and L-NAME significantly inhibited the repaired effect of H2 on LPS-induced dysfunctions of EPCs. H2 also restored levels of phosphor-AKT (p-AKT), eNOS and phosphor-eNOS (p-eNOS) suppressed by LPS. LY294002 significantly inhibited the increase of p-AKT and eNOS and p-eNOS expression exposed by H2. L-NAME significantly inhibited the increase of eNOS and p-eNOS expression induced by H2. H2 repairs the dysfunctions of EPCs induced by LPS, which is mediated by PI3K/AKT/eNOS signaling pathway.

Non-Coding RNAs in Sepsis-Associated Acute Kidney Injury

Sepsis is a systemic inflammatory response caused by a severe infection that leads to multiple organ damage, including acute kidney injury (AKI). In intensive care units (ICU), the morbidity and mortality associated with sepsis-associated AKI (SA-AKI) are gradually increasing due to lack of effective and early detection, as well as proper treatment. Non-coding RNAs (ncRNAs) exert a regulatory function in gene transcription, RNA processing, post-transcriptional translation, and epigenetic regulation of gene expression. Evidence indicated that miRNAs are involved in inflammation and programmed cell death during the development of sepsis-associated AKI (SA-AKI). Moreover, lncRNAs and circRNAs appear to be an essential regulatory mechanism in SA-AKI. In this review, we summarized the molecular mechanism of ncRNAs in SA-AKI and discussed their potential in clinical diagnosis and treatment.

Circular RNA mmu_circ_0001295 from hypoxia pretreated adipose-derived mesenchymal stem cells (ADSCs) exosomes improves outcomes and inhibits sepsis-induced renal injury in a mouse model of sepsis

Microvascular dysfunction causes mortality in the presence of sepsis and multi-organ failure. Previous studies have demonstrated that exogenous administration of exosomes from adipose-derived mesenchymal stem cells (ADSCs) protects against sepsis, improves organ function, decreases vascular leakage and increases survival. However, the underlying regulatory mechanism was largely unknown. Therefore, in this study, a mouse sepsis model based on cecal ligation and puncture (CLP) was constructed. Exosomes from various ADSCs were intravenously administered at 4 h post CLP. Treatment with ADSC exosomes (Exo), particularly those with hypoxic pretreatment (HExo), enhanced survival, suppressed renal vascular leakage and decreased kidney dysfunction in septic mice. HExo ameliorated sepsis-induced increases in chemokine and cytokine plasma levels. Furthermore, the HExo circRNA content, determined through next-generation sequencing, revealed abundant mmu_circ_0001295. Further studies demonstrated that downregulation of exosomal mmu_circ_0001295 suppressed the exosomes' protective effects against sepsis. HExo prevented microvascular dysfunction, thus potentially improving sepsis outcomes via mmu_circ_0001295 delivery. In summary, the data indicated that HExo elongate sepsis-induced renal injury through delivering mmu_circ_0001295.

Latest Advances in Endothelial Progenitor Cell-Derived Extracellular Vesicles Translation to the Clinic

Almost all nucleated cells secrete extracellular vesicles (EVs) that are heterogeneous spheroid patterned or round shape particles ranging from 30 to 200 nm in size. Recent preclinical and clinical studies have shown that endothelial progenitor cell-derived EVs (EPC-EVs) have a beneficial therapeutic effect in various diseases, including cardiovascular diseases and kidney, and lung disorders. Moreover, some animal studies have shown that EPC-EVs selectively accumulate at the injury site with a specific mechanism of binding along with angiogenic and restorative effects that are superior to those of their ancestors. This review article highlights current advances in the biogenesis, delivery route, and long-term storage methods of EPC-EVs and their favorable effects such as anti-inflammatory, angiogenic, and tissue protection in various diseases. Finally, we review the possibility of therapeutic application of EPC-EVs in the clinic.

Inhibition of miR-1298-5p attenuates sepsis lung injury by targeting SOCS6

Sepsis is one of the leading causes of morbidity and mortality and a major cause of acute lung injury (ALI). carried by exosomes play a role in a variety of diseases. However,there are not many studies of exosomal miRNAs in sepsis and sepsis lung injury.miR-1298-5p and suppressor of cytokine signaling 6 (SOCS6) were silenced or overexpressed in human bronchial epithelial cells (BEAS-2B). PKH-67 Dye was used to trace exosome endocytosis. Cell permeability was evaluated by measuring trans-epithelial electrical resistance (TEER) and FITC dextran flux. ELISA kits were used for cytokine detection. Quantitative RT-PCR and western blots were used to evaluate gene expression. miR-1298-5p was elevated in exosomes from patients with sepsis lung injury (Sepsis_exo). Treatment of BEAS-2B cells using Sepsis_exo significantly inhibited cell proliferation, and induced cell permeability and inflammatory response. miR-1298-5p directly targeted SOCS6. Overexpressing SOCS6 reversed miR-1298-5p-induced cell permeability and inflammatory response. Inhibition of STAT3 blocked SOCS6-silencing caused significant increase of cell permeability and inflammation. Exosomes isolated from patients of sepsis lung injury increased cell permeability and inflammatory response in BEAS-2B cells through exosomal miR-1298-5p which targeted SOCS6 via STAT3 pathway. The findings highlight the importance of miR-1298-5p/SOCS6/STAT3 axis in sepsis lung injury and provide new insights into therapeutic strategies for sepsis lung injury.

Cardioprotective Roles of Endothelial Progenitor Cell-Derived Exosomes

With the globally increasing prevalence, cardiovascular diseases (CVDs) have become the leading cause of mortality. The transplantation of endothelial progenitor cells (EPCs) holds a great promise due to their potential for vasculogenesis, angiogenesis, and protective cytokine release, whose mechanisms are essential for CVD therapies. In reality, many investigations have attributed the therapeutic effects of EPC transplantation to the secretion of paracrine factors rather than the differentiation function. Of note, previous studies have suggested that EPCs could also release exosomes (diameter range of 30–150 nm), which carry various lipids and proteins and are abundant in microRNAs. The EPC-derived exosomes (EPC-EXs) were reported to act on the heart and blood vessels and were implicated in anti-inflammation, anti-oxidation, anti-apoptosis, the inhibition of endothelial-to-mesenchymal transition (EndMT), and cardiac fibrosis, as well as anti-vascular remodeling and angiogenesis, which were considered as protective effects against CVDs. In this review, we summarize the current knowledge on using EPC-EXs as therapeutic agents and provide a detailed description of their identified mechanisms of action to promote the prognosis of CVDs.

FGF23 ameliorates ischemia-reperfusion induced acute kidney injury via modulation of endothelial progenitor cells: targeting SDF-1/CXCR4 signaling

The levels of fibroblast growth factor 23 (FGF23) rapidly increases after acute kidney injury (AKI). However, the role of FGF23 in AKI is still unclear. Here, we observe that pretreatment with FGF23 protein into ischemia-reperfusion induced AKI mice ameliorates kidney injury by promoting renal tubular regeneration, proliferation, vascular repair, and attenuating tubular damage. In vitro assays demonstrate that SDF-1 induces upregulation of its receptor CXCR4 in endothelial progenitor cells (EPCs) via a non-canonical NF-κB signaling pathway. FGF23 crosstalks with the SDF-1/CXCR4 signaling and abrogates SDF-1-induced EPC senescence and migration, but not angiogenesis, in a Klotho-independent manner. The downregulated pro-angiogenic IL-6, IL-8, and VEGF-A expressions after SDF-1 infusion are rescued after adding FGF23. Diminished therapeutic ability of SDF-1-treated EPCs is counteracted by FGF23 in a SCID mouse in vivo AKI model. Together, these data highlight a revolutionary and important role that FGF23 plays in the nephroprotection of IR-AKI.

Experimental Study on the Effect of Allogeneic Endothelial Progenitor Cells on Wound Healing in Diabetic Mice

Endothelial progenitor cells (EPCs) are involved in the neovascularization in traumatic and ischemic sites, but EPCs are "detained" in bone marrow under diabetic conditions, which results in reduction of the number of EPCs and their biological activity in peripheral blood. Based on our previous study to mobilize autologous bone marrow EPCs by administering AMD3100+G-CSF to realize the optimal effect, our present study is aimed at exploring the effects of transplanting EPCs locally in a wound model of diabetic mice. First, we prepared and identified EPCs, and the biological functions and molecular characteristics were compared between EPCs from DB/+ and DB/DB mice. Then, we performed full-thickness skin resection in DB/DB mice and tested the effect of local transplantation of EPCs on skin wound healing. The wound healing process was recorded using digital photographs. The animals were sacrificed on postoperative days 7, 14, and 17 for histological and molecular analysis. Our results showed that DB/+ EPCs were biologically more active than those of DB/DB EPCs. When compared with the control group, local transplantation of EPCs accelerated wound healing in DB/DB mice by promoting wound granulation tissue formation, angiogenesis, and collagen fiber deposition, but there was no significant difference in wound healing between DB/+ EPCs and DB/DB EPCs transplanted into the wound. Furthermore, local transplantation of EPCs promoted the expression of SDF-1, CXCR4, and VEGF. We speculated that EPC transplantation may promote wound healing through the SDF-1/CXCR4 axis. This point is worth exploring further. Present data are of considerable significance because they raise the possibility of promoting wound healing by isolating autologous EPCs from the patient, which provides a new approach for the clinical treatment of diabetic wounds in the future.

Pathogenetic Substantiation of Therapeutic and Preventive Measures in Severe Coronavirus Infection

The basis of coronavirus disease is an infectious process, accompanied by a varying degree of activity of pathological processes. Based on the study of the pathological course of infection, modern approaches to the treatment and prevention of complications of coronavirus infection are presented. The main strategic pathogenetic direction in the creation of effective programs for the treatment of COVID-19, as well as the prevention of fatal complications, should be a set of measures enhancing permissive regulatory influences and events. Endothelium, being a source of inflammatory mediators and a transducer of their regulatory effects on the vascular tone, is involved in the development and alternation of vascular reactions, changing the volume of perfusion. The main mechanism for the development of endothelial dysfunction and damage is associated with an imbalance between the generation of reactive oxygen species and the power of the antioxidant defense system. Any measures to protect the endothelium, reducing the severity of microcirculatory disorders and hypoxia, will have a therapeutic and preventive effect on fatal complications. In this regard, in the treatment of COVID-19, the use of synthetic gas transport preparations based on perfluorocarbon nanodispersed emulsions with a clinical effect directed at once to several patho-genetic links underlying the progression of COVID-19 disease can be quite effective. The necessity of a comprehensive effect on pathogenesis using sanogenetic principles of treatment, allowing influencing the speed and time of onset of resolution of inflammation, which can reduce the number of complications and deaths of the disease, is substantiated.

The Heat Shock Protein 70 Plays a Protective Role in Sepsis by Maintenance of the Endothelial Permeability

Sepsis is a severe system inflammatory response syndrome in response to infection. The vascular endothelium cells play a key role in sepsis-induced organ dysfunction. The heat shock protein 70 (HSP70) has been reported to play an anti-inflammatory role and protect from sepsis. The present study is aimed at finding the function of HSP70 against sepsis in vascular endothelium cells. Lipopolysaccharide (LPS) and HSP70 agonist and inhibitor were used to treat HUVEC. Cell permeability was measured by transepithelial electrical resistance (TEER) assay and FITC-Dextrans. Cell junction protein levels were measured by western blot. Mice were subjected to cecal ligation and puncture (CLP) to establish a sepsis model and were observed for survival. After LPS incubation, HSP70 expression was decreased in HUVEC. LPS induced the inhibition of cell viability and the increases of IL-1β, IL-6, and TNF-α. Furthermore, cell permeability was increased and cell junction proteins (E-cadherin, occludin, and ZO-1) were downregulated after treatment with LPS. However, HSP70 could reverse these effects induced by LPS in HUVEC. In addition, LPS-induced elevated phosphorylation of p38 can be blocked by HSP70. On the other hand, we found that inhibition of HSP70 had similar effects as LPS and these effects could be alleviated by the inhibitor of p38. Subsequently, HSP70 was also found to increase survival of sepsis mice in vivo. In conclusion, HSP70 plays a protective role in sepsis by maintenance of the endothelial permeability via regulating p38 signaling.

Non-coding RNAs and Exosomes: Their Role in the Pathogenesis of Sepsis

Sepsis is characterized as an uncontrolled host response to infection, and it represents a serious health challenge, causing excess mortality and morbidity worldwide. The discovery of sepsis-related epigenetic and molecular mechanisms could result in improved diagnostic and therapeutic approaches, leading to a reduced overall risk for affected patients. Accumulating data show that microRNAs, non-coding RNAs, and exosomes could all be considered as novel diagnostic markers for sepsis patients. These biomarkers have been demonstrated to be involved in regulation of sepsis pathophysiology. However, epigenetic modifications have not yet been widely reported in actual clinical settings, and further investigation is required to determine their importance in intensive care patients. Further studies should be carried out to explore tissue-specific or organ-specific epigenetic RNA-based biomarkers and their therapeutic potential in sepsis patients.

Vagal α7nAChR signaling regulates α7nAChR+Sca1+ cells during lung injury repair

Background

The distal airways of the lung and bone marrow are innervated by the vagus nerve. Vagal α7nAChR signaling plays a key role in regulating lung infection and inflammation; however, whether this pathway regulates α7nAChR⁺Sca1⁺ cells during lung injury repair remains unknown. We hypothesized that vagal α7nAChR signaling controls α7nAChR⁺Sca1⁺ cells, which contribute to the resolution of lung injury.

Methods

Pneumonia was induced by intratracheal challenge with E. coli. The bone marrow mononuclear cells (BM-MNCs) were isolated from the bone marrow of pneumonia mice for immunofluorescence. The bone marrow, blood, BAL, and lung cells were isolated for flow cytometric analysis by labeling with anti-Sca1, VE-cadherin, p-Akt1, or Flk1 antibodies. Immunofluorescence was also used to examine the coexpression of α7nAChR, VE-cadherin, and p-Akt1. Sham, vagotomized, α7nAChR knockout, and Akt1 knockout mice were infected with E. coli to study the regulatory role of vagal α7nAChR signaling and Akt1 in Sca1⁺ cells.

Results

During pneumonia, BM-MNCs were enriched with α7nAChR⁺Sca1⁺ cells, and this cell population proliferated. Transplantation of pneumonia BM-MNCs could mitigate lung injury and increase engraftment in recipient pneumonia lungs. Activation of α7nAChR by its agonist could boost α7nAChR⁺Sca1⁺ cells in the bone marrow, peripheral blood, and bronchoalveolar lavage (BAL) in pneumonia. Immunofluorescence revealed that α7nAChR, VE-cadherin, and p-Akt1 were coexpressed in the bone marrow cells. Vagotomy could reduce α7nAChR⁺VE-cadherin⁺ and VE-cadherin⁺p-Akt1⁺ cells in the bone marrow in pneumonia. Knockout of α7nAChR reduced VE-cadherin⁺ cells and p-Akt1⁺ cells in the bone marrow. Deletion of Akt1 reduced Sca1⁺ cells in the bone marrow and BAL. More importantly, 91.3 ± 4.9% bone marrow and 77.8 ± 4.9% lung α7nAChR⁺Sca1⁺VE-cadherin⁺ cells expressed Flk1, which is a key marker of endothelial progenitor cells (EPCs). Vagotomy reduced α7nAChR⁺Sca1⁺VE-cadherin⁺p-Akt1⁺ cells in the bone marrow and lung from pneumonia mice. Treatment with cultured EPCs reduced ELW compared to PBS treatment in E. coli pneumonia mice at 48 h. The ELW was further reduced by treatment with EPCs combining with α7nAChR agonist-PHA568487 compared to EPC treatments only.

Conclusions

Vagal α7nAChR signaling regulates α7nAChR⁺Sca1⁺VE-cadherin⁺ EPCs via phosphorylation of Akt1 during lung injury repair in pneumonia.

miR-145a Regulation of Pericyte Dysfunction in a Murine Model of Sepsis

BACKGROUND

Sepsis is a life-threatening systemic disease with severe microvascular dysfunction. Pericytes preserve vascular homeostasis. To our knowledge, the potential roles of microRNAs in sepsis-induced pericyte dysfunction have not been explored.

METHODS

We determined lung pericyte expression of miR-145a in cecal ligation and puncture (CLP)-induced sepsis. Mouse lung pericytes were isolated and transfected with a miR-145a mimic, followed by stimulation with lipopolysaccharide (LPS). We measured inflammatory cytokine levels. To assess the functions of miR-145a in vivo, we generated a pericyte-specific miR-145a-knockout mouse and determined sepsis-induced organ injury, lung and renal vascular leakage, and mouse survival rates. We used RNA sequencing and Western blotting to analyze the signaling pathways regulated by miR-145a.

RESULTS

CLP led to decreased miR-145a expression in lung pericytes. The miR-145a mimic inhibited LPS-induced increases in cytokines. In CLP-induced sepsis, pericytes lacking miR-145a exhibited increased lung and kidney vascular leakage and reduced survival rates. We found that miR-145a could suppress LPS-induced NF-κB activation. In addition, we confirmed that the transcription factor Friend leukemia virus integration 1 (Fli-1) is a target of miR-145a and that Fli-1 activates NF-κB signaling.

CONCLUSION

Our results demonstrated that pericyte miR-145a mediates sepsis-associated microvascular dysfunction, potentially by means of Fli-1-mediated modulation of NF-κB signaling.

Endothelial progenitor cells-secreted extracellular vesicles containing microRNA-93-5p confer protection against sepsis-induced acute kidney injury via the KDM6B/H3K27me3/TNF-α axis

The pivotal pathogenetic role of microRNAs (miRs) in sepsis-induced acute kidney injury (AKI) has been demonstrated in mounting evidence. The functions of the target cells are regulated through the release of cells-encapsulated extracellular vesicles (Evs) into the extracellular space. The present study aims to elucidate the clinical significance as well as biological function of the endothelial progenitor cell (EPC)-derived Evs containing miR-93-5p in sepsis-induced AKI. We first established a cellular sepsis-induced AKI mouse model by treatment with lipopolysaccharide (LPS), and tested ectopic expression and depletion experiments in the model. Evs derived from miR-93-5p inhibitor-transfected EPCs (Evs/miR-93-5p inhibitor) were isolated, and co-cultured with HK2 cells to explore the effects of EPC-derived Evs overexpressing miR-93-5p on LPS-induced HK2 cell injury. The interaction between miR-93-5p and lysine (K)-specific demethylase 6B (KDM6B) was identified using dual-luciferase reporter assay, and ChIP was used to validate the relationship between KDM6B and tumor necrosis factor-α (TNF-α). Mice were made septic by cecal ligation and puncture (CLP), and then injected with Ev/miR-93-5p inhibitor to explore its functions in vivo. The results found that miR-93-5p and histone H3 Lys27 trimethylation (H3K27me3) were downregulated while KDM6B was upregulated in LPS-treated HK2 cells. EPC-derived Evs alleviated LPS-induced HK2 cell injury, while Ev/miR-93-5p inhibitor potentiated the cell injury in vitro. miR-93-5p was found to directly target KDM6B. Silencing KDM6B induced H3K27me3, inhibiting the activation of TNF-α, thereby weakening LPS-induced HK2 cell injury. EPC-derived Evs containing miR-93-5p attenuated multiple organ injury, vascular leakage, inflammation, and apoptosis in septic mice. In conclusion, the present study demonstrated that endothelial protection from EPC-derived Evs carrying miR-93-5p in sepsis-induced AKI, which was mediated by regulation KDM6BH/3K27me3/TNF-α axis.

High mobilization of CD133+/CD34+ cells expressing HIF-1α and SDF-1α in septic abdominal surgical patients

Background

The control of endothelial progenitor cells (CD133+/CD34+ EPCs) migrating from bone marrow to peripheral blood is not completely understood. Emerging evidence suggests that stromal cell-derived factor-1α (SDF-1α) mediates egression of EPCs from bone marrow, while the hypoxia inducible factor (HIF) transcriptional system regulates SDF-1α expression. Our study aimed to investigate the time course of circulating CD133+/CD34+ EPCs and its correlation with the expression of HIF-1α protein and SDF-1α in postoperative laparoscopic abdominal septic patients.

Methods

Postoperative patients were divided in control (C group) and septic group (S group) operated immediately after the diagnosis of sepsis/septic shock. Blood samples were collected at baseline (0), 1, 3 and 7 postoperative days for CD133+/CD34+ EPCs count expressing or not the HIF-1α and SDF-1α analysis.

Results

Thirty-two patients in S group and 39 in C group were analyzed. In C group CD133+/CD34+ EPCs count remained stable throughout the study period, increasing on day 7 (173 [0–421] /μl vs baseline: P = 0.04; vs day 1: P = 0.002). In S group CD133+/CD34+ EPCs count levels were higher on day 3 (vs day 1: P = 0.006 and day 7: P = 0.026). HIF-1α expressing CD133+/CD34+ EPCs count decreased on day 1 as compared with the other days in C group (day 0 vs 1: P = 0.003, days 3 and 7 vs 1: P = 0.008), while it was 321 [0–1418] /μl on day 3 (vs day 1; P = 0.004), and 400 [0–587] /μl on day 7 in S group. SDF-1α levels were higher not only on baseline but also on postoperative day 1 in S vs C group (219 [124–337] pg/ml vs 35 [27–325] pg/ml, respectively; P = 0.01).

Conclusion

Our results indicate that sepsis in abdominal laparoscopic patients might constitute an additional trigger of the EPCs mobilization as compared with non-septic surgical patients. A larger mobilization of CD133+/CD34+ EPCs, preceded by enhanced plasmatic SDF-1α, occurs in septic surgical patients regardless of HIF-1α expression therein.

Trial registration

ClinicalTrials.gov no. NCT02589535. Registered 28 October 2015.

Circulating miRNA 887 is differentially expressed in ARDS and modulates endothelial function

Circulating microRNAs (miRNAs) can be taken up by recipient cells and have been recently associated with the acute respiratory distress syndrome (ARDS). Their role in host predisposition to the syndrome is unknown. The objective of the study was to identify circulating miRNAs associated with the development of sepsis-related ARDS and examine their impact on endothelial cell gene expression and function. We determined miRNA levels in plasma collected from subjects during the first 24 h of admission to a tertiary intensive care unit for sepsis. A miRNA that was differentially expressed between subjects who did and did not develop ARDS was identified and was transfected into human pulmonary microvascular endothelial cells (HPMECs). RNA sequencing, in silico analysis, cytokine expression, and leukocyte migration assays were used to determine the impact of this miRNA on gene expression and cell function. In two cohorts, circulating miR-887-3p levels were elevated in septic patients who developed ARDS compared with those who did not. Transfection of miR-887-3p into HPMECs altered gene expression, including the upregulation of several genes previously associated with ARDS (e.g., CXCL10, CCL5, CX3CL1, VCAM1, CASP1, IL1B, IFNB, and TLR2), and activation of cellular pathways relevant to the response to infection. Functionally, miR-887-3p increased the endothelial release of chemokines and facilitated trans-endothelial leukocyte migration. Circulating miR-887-3p is associated with ARDS in critically ill patients with sepsis. In vitro, miR-887-3p regulates the expression of genes relevant to ARDS and neutrophil tracking. This miRNA may contribute to ARDS pathogenesis and could represent a novel therapeutic target.

Effects of Bacterial Translocation and Autophagy on Acute Lung Injury Induced by Severe Acute Pancreatitis

Aim

To reveal the role of bacterial translocation (BT) and autophagy in severe acute pancreatitis-induced acute lung injury (SAP-ALI).

Methods

Rats were separated into a control (sham-operation) group (n = 10) and a SAP group (n = 10) and a SAP group (

Results

Levels of TNF-α, IL-6, lipase, and amylase in the SAP group were significantly higher than those in the control group (P < 0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (P < 0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (P < 0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (P < 0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (P < 0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (P < 0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (

Conclusions

BT can aggravate SAP-ALI with the increasing oxidative stress level, which may be related to the decrease of autophagy level.

Sepsis: From Historical Aspects to Novel Vistas. Pathogenic and Therapeutic Considerations

BACKGROUND

Sepsis is a clinical condition due to an infectious event which leads to an early hyper-inflammatory phase followed by a status of tolerance or immune paralysis. Hyper-inflammation derives from a massive activation of immune (neutrophils, monocytes/macrophages, dendritic cells and lymphocytes) and non-immune cells (platelets and endothelial cells) in response to Gram-negative and Gram-positive bacteria and fungi.

DISCUSSION

A storm of pro-inflammatory cytokines and reactive oxygen species accounts for the systemic inflammatory response syndrome. In this phase, bacterial clearance may be associated with a severe organ failure development. Tolerance or compensatory anti-inflammatory response syndrome (CARS) depends on the production of anti-inflammatory mediators, such as interleukin-10, secreted by T regulatory cells. However, once triggered, CARS, if prolonged, may also be detrimental to the host, thus reducing bacterial clearance.

CONCLUSION

In this review, the description of pathogenic mechanisms of sepsis is propaedeutic to the illustration of novel therapeutic attempts for the prevention or attenuation of experimental sepsis as well as of clinical trials. In this direction, inhibitors of NF-κB pathway, cell therapy and use of dietary products in sepsis will be described in detail.

Reverse-D-4F improves endothelial progenitor cell function and attenuates LPS-induced acute lung injury

Background

Patients with acute lung injury (ALI) have increased levels of pro-inflammatory mediators, which impair endothelial progenitor cell (EPC) function. Increasing the number of EPC and alleviating EPC dysfunction induced by pro-inflammatory mediators play important roles in suppressing ALI development. Because the high density lipoprotein reverse-D-4F (Rev-D4F) improves EPC function, we hypothesized that it might repair lipopolysaccharide (LPS)-induced lung damage by improving EPC numbers and function in an LPS-induced ALI mouse model.

Methods

LPS was used to induce ALI in mice, and then the mice received intraperitoneal injections of Rev-D4F. Immunohistochemical staining, flow cytometry, MTT, transwell, and western blotting were used to assess the effect of Rev-D4F on repairment of lung impairment, and improvement of EPC numbers and function, as well as the signaling pathways involved.

Results

Rev-D4F inhibits LPS-induced pulmonary edema and decreases plasma levels of the pro-inflammatory mediators TNF-α and ET-1 in ALI mice. Rev-D4F inhibited infiltration of red and white blood cells into the interstitial space, reduced lung injury-induced inflammation, and restored injured pulmonary capillary endothelial cells. In addition, Rev-D4F increased numbers of circulating EPC, stimulated EPC differentiation, and improved EPC function impaired by LPS. Rev-D4F also acted via a PI3-kinase-dependent mechanism to restore levels of phospho-AKT, eNOS, and phospho-eNOS suppressed by LPS.

Conclusions

These findings indicate that Rev-D4F has an important vasculoprotective role in ALI by improving the EPC numbers and functions, and Rev-D4F reverses LPS-induced EPC dysfuncion partially through PI3K/AKT/eNOS signaling pathway.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1099-6) contains supplementary material, which is available to authorized users.

Endothelial progenitor cell transplantation attenuates lipopolysaccharide-induced acute lung injury via regulating miR-10a/b-5p

Background

Bone marrow-derived endothelial progenitor cells (EPCs) are shown to attenuate lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in animal models. However, the molecular mechanism is largely unknown.

Materials and methods

The animal model of ALI was induced by intratracheal instillation of purified LPS with 2.5 mg/ml/kg. The expression of microRNAs and ADAM15 in lung tissues and LPS-induced mouse pulmonary microvascular endothelial cells (MPMVECs) was determined by quantitative real-time PCR and western blot analysis. The target relationship between miR-10a/b-5p and ADAM15 was confirmed by luciferase reporter assay and RNA interference. The effect of EPCs on MPMVEC proliferation was detected by MTT assay.

Results

EPCs increased the expression of miR-10a/b-5p and reduced ADAM15 protein level in LPS-induced ALI lung tissues and MPMVECs (p < 0.05), and promoted LPS-induced MPMVEC proliferation (p < 0.05). ADAM15 was confirmed to be a downstream target of miR-10a/b-5p. Additionally, EPCs promoted LPS-induced MPMVEC proliferation and exerted the therapeutic effect of ALI via regulating miR-10a/b-5p/ADAM15 axis.

Conclusion

EPC transplantation exerted its therapeutic effect of ALI via increasing miR-10a/b-5p and reducing ADAM15, thus providing a novel insight into the molecular mechanism of EPC transplantation in treating ALI.

Electronic supplementary material

The online version of this article (10.1186/s12944-019-1079-3) contains supplementary material, which is available to authorized users.

Clinical Assessment of Intravenous Endothelial Progenitor Cell Transplantation in Dogs

Endothelial progenitor cells (EPCs) have been applied for cell therapy because of their roles in angiogenesis and neovascularization in ischemic tissue. However, adverse responses caused by EPC therapy have not been fully investigated. In this study, a human peripheral blood sample was collected from a healthy donor and peripheral blood mononuclear cells were separated using Ficoll-Hypaque. There were four experimental groups: 10 ml saline infusion group (injection rate; 3 ml/min), 10 ml saline bolus group (injection rate; 60 ml/min), 10 ml EPCs infusion group (2 x 10⁵ cells/ml, injection rate; 3 ml/min), 10 ml EPCs bolus group (2 × 10⁵ cells/ml, injection rate; 60 ml/min). Clinical assessment included physical examination and laboratory examination for intravenous human EPC transplantation in dogs. The results revealed no remarkable findings in vital signs among the dogs used. In blood analysis, platelet counts in saline infusion groups were significantly higher than in the EPC groups within normal ranges, and no significant differences were observed except K⁺, Cl^- and blood urea nitrogen/urea. In ELISA assay, no significant difference was observed in serum tumor necrosis factor alpha. The serum concentration of vascular endothelial growth factor was significantly higher in EPC groups than in saline groups, and interleukin 10 was significantly up-regulated in the EPC infusion group compared with other groups. In conclusion, we demonstrated that no clinical abnormalities were detected after intravenous transplantation of human EPCs in dogs. The transplanted xenogenic EPCs might be involved in anti-inflammatory and angiogenic functions in dogs.

Putative endothelial progenitor cells do not promote vascular repair but attenuate pericyte-myofibroblast transition in UUO-induced renal fibrosis

Background

Putative endothelial progenitor cells (pEPCs) have been confirmed to participate in alleviation of renal fibrosis in several ischaemic diseases. However, their mechanistic effect on renal fibrosis, which is characterized by vascular regression and further rarefaction-related pathology, remains unknown.

Methods

To explore the effect and molecular mechanisms by which pEPCs act on unilateral ureteral obstruction (UUO)-induced renal fibrosis, we isolated pEPCs from murine bone marrow. In vivo, pEPCs (2 × 10⁵ cells/day) and pEPC-MVs (microvesicles) were injected into UUO mice via the tail vein. In vitro, pEPCs were co-cultured with renal-derived pericytes. Pericyte-myofibroblast transition was evaluated using the myofibroblast marker α-smooth muscle actin (α-SMA) and pericyte marker platelet-derived growth factor receptor β (PDGFR-β).

Results

Exogenous supply of bone marrow-derived pEPCs attenuated renal fibrosis by decreasing pericyte-myofibroblast transition without significant vascular repair in the UUO model. Our results indicated that pEPCs regulated pericytes and their transition into myofibroblasts via pEPC-MVs. Co-culture of pericytes with pEPCs in vitro suggested that pEPCs inhibit transforming growth factor-β (TGF-β)-induced pericyte–myofibroblast transition via a paracrine pathway.

Conclusion

pEPCs effectively attenuated UUO-induced renal fibrosis by inhibiting pericyte–myofibroblast transition via a paracrine pathway, without promoting vascular repair.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1201-5) contains supplementary material, which is available to authorized users.

Exosomes from endothelial progenitor cells improve outcomes of the lipopolysaccharide-induced acute lung injury

Background

The acute respiratory distress syndrome (ARDS) is characterized by disruption of the alveolar-capillary barrier resulting in accumulation of proteinaceous edema and increased inflammatory cells in the alveolar space. We previously found that endothelial progenitor cell (EPC) exosomes prevent endothelial dysfunction and lung injury in sepsis in part due to their encapsulation of miRNA-126. However, the effects of EPC exosomes in acute lung injury (ALI) remain unknown.

Methods

To determine if EPC exosomes would have beneficial effects in ALI, intratracheal administration of lipopolysaccharide (LPS) was used to induce ALI in mice. Lung permeability, inflammation, and the role of miRNA-126 in the alveolar-epithelial barrier function were examined.

Results

The intratracheal administration of EPC exosomes reduced lung injury following LPS-induced ALI at 24 and 48 h. Compared to placebo, intratracheal administration of EPC exosomes significantly reduced the cell number, protein concentration, and cytokines/chemokines in the bronchoalveolar lavage fluid (BALF), indicating a reduction in permeability and inflammation. Further, EPC exosomes reduced myeloperoxidase (MPO) activity, lung injury score, and pulmonary edema, demonstrating protection against lung injury. Murine fibroblast (NIH3T3) exosomes, which do not contain abundant miRNA-126, did not provide these beneficial effects. In human small airway epithelial cells (SAECs), we found that overexpression of miRNA-126-3p can target phosphoinositide-3-kinase regulatory subunit 2 (PIK3R2), while overexpression of miRNA-126-5p inhibits the inflammatory alarmin HMGB1 and permeability factor VEGFα. Interestingly, both miR-126-3p and 5p increase the expression of tight junction proteins suggesting a potential mechanism by which miRNA-126 may mitigate LPS-induced lung injury.

Conclusions

Our data demonstrated that human EPC exosomes are beneficial in LPS-induced ALI mice, in part through the delivery of miRNA-126 into the injured alveolus.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2339-3) contains supplementary material, which is available to authorized users.

Application of Deacetylated Poly-N-Acetyl Glucosamine Nanoparticles for the Delivery of miR-126 for the Treatment of Cecal Ligation and Puncture-Induced Sepsis

Sepsis is an acute inflammatory syndrome in response to infection. In some cases, excessive inflammation from sepsis results in endothelial dysfunction and subsequent increased vascular permeability leading to organ failure. We previously showed that treatment with endothelial progenitor cells, which highly express microRNA-126 (miR-126), improved survival in mice subjected to cecal ligation and puncture (CLP) sepsis. miRNAs are important regulators of gene expression and cell function, play a major role in endothelial homeostasis, and may represent an emerging therapeutic modality. However, delivery of miRNAs to cells in vitro and in vivo is challenging due to rapid degradation by ubiquitous RNases. Herein, we developed a nanoparticle delivery system separately combining deacetylated poly-N-acetyl glucosamine (DEAC-pGlcNAc) polymers with miRNA-126-3p and miRNA-126-5p and testing these combinations in vitro and in vivo. Our results demonstrate that DEAC-pGlcNAc polymers have an appropriate size and zeta potential for cellular uptake and when complexed, DEAC-pGlcNAc protects miRNA from RNase A degradation. Further, DEAC-pGlcNAc efficiently encapsulates miRNAs as evidenced by preventing their migration in an agarose gel. The DEAC-pGlcNAc-miRNA complexes were taken up by multiple cell types and the delivered miRNAs had biological effects on their targets in vitro including pERK and DLK-1. In addition, we found that delivery of DEAC-pGlcNAc alone or DEAC-pGlcNAc:miRNA-126-5p nanoparticles to septic animals significantly improved survival, preserved vascular integrity, and modulated cytokine production. These composite studies support the concept that DEAC-pGlcNAc nanoparticles are an effective platform for delivering miRNAs and that they may provide therapeutic benefit in sepsis.

Fli-1 Governs Pericyte Dysfunction in a Murine Model of Sepsis

Background

Pericytes are vascular mural cells and are embedded in the basement membrane of the microvasculature. Recent studies suggest a role for pericytes in lipopolysaccharide (LPS)-induced microvascular dysfunction and mortality, but the mechanisms of pericyte loss in sepsis are largely unknown.

Methods

By using a cecal ligation and puncture (CLP)-induced murine model of sepsis, we observed that CLP led to lung and renal pericyte loss and reduced lung pericyte density and pericyte/endothelial cell (EC) coverage.

Results

Up-regulated Friend leukemia virus integration 1 (Fli-1) messenger ribonucleic acid (RNA) and protein levels were found in lung pericytes from CLP mice in vivo and in LPS-stimulated lung pericytes in vitro. Knockout of Fli-1 in Foxd1-derived pericytes prevented CLP-induced pericyte loss, vascular leak, and improved survival. Disrupted Fli-1 expression by small interfering RNA inhibited LPS-induced inflammatory cytokines and chemokines in cultured lung pericytes. Furthermore, CLP-induced pericyte pyroptosis was mitigated in pericyte Fli-1 knockout mice.

Conclusions

Our findings suggest that Fli-1 is a potential therapeutic target in sepsis.

Delay in antibiotic therapy results in fatal disease outcome in murine pneumococcal pneumonia

BACKGROUND

Community-acquired pneumonia (CAP) remains a major cause of death worldwide. Mechanisms underlying the detrimental outcome despite adequate antibiotic therapy and comorbidity management are still not fully understood.

METHODS

To model timely versus delayed antibiotic therapy in patients, mice with pneumococcal pneumonia received ampicillin twice a day starting early (24 h) or late (48 h) after infection. Clinical readouts and local and systemic inflammatory mediators after early and late antibiotic intervention were examined.

RESULTS

Early antibiotic intervention rescued mice, limited clinical symptoms and restored fitness, whereas delayed therapy resulted in high mortality rates. Recruitment of innate immune cells remained unaffected by antibiotic therapy. However, both early and late antibiotic intervention dampened local levels of inflammatory mediators in the alveolar spaces. Early treatment protected from barrier breakdown, and reduced levels of vascular endothelial growth factor (VEGF) and perivascular and alveolar edema formation. In contrast, at 48 h post infection, increased pulmonary leakage was apparent and not reversed by late antibiotic treatment. Concurrently, levels of VEGF remained high and no beneficial effect on edema formation was evident despite therapy. Moreover, early but not late treatment protected mice from a vast systemic inflammatory response.

CONCLUSIONS

Our data show that only early antibiotic therapy, administered prior to breakdown of the alveolar-capillary barrier and systemic inflammation, led to restored fitness and rescued mice from fatal streptococcal pneumonia. The findings highlight the importance of identifying CAP patients prior to lung barrier failure and systemic inflammation and of handling CAP as a medical emergency.

CXCR-4 expression by circulating endothelial progenitor cells and SDF-1 serum levels are elevated in septic patients

Background

Endothelial progenitor cell (EPC) numbers are increased in septic patients and correlate with survival. In this study, we investigated, whether surface expression of chemokine receptors and other receptors important for EPC homing is upregulated by EPC from septic patients and if this is associated with clinical outcome.

Methods

Peripheral blood mononuclear cells from septic patients (n = 30), ICU control patients (n = 11) and healthy volunteers (n = 15) were isolated by Ficoll density gradient centrifugation. FACS-analysis was used to measure the expression of the CXC motif chemokine receptors (CXCR)-2 and − 4, the receptor for advanced glycation endproducts (RAGE) and the stem cell factor receptor c-Kit. Disease severity was assessed via the Simplified Acute Physiology Score (SAPS) II. The serum concentrations of vascular endothelial growth factor (VEGF), stromal cell-derived factor (SDF)-1α and angiopoietin (Ang)-2 were determined with Enzyme linked Immunosorbent Assays.

Results

EPC from septic patients expressed significantly more CXCR-4, c-Kit and RAGE compared to controls and were associated with survival-probability. Significantly higher serum concentrations of VEGF, SDF-1α and Ang-2 were found in septic patients. SDF-1α showed a significant association with survival.

Conclusions

Our data suggest that SDF-1α and CXCR-4 signaling could play a crucial role in EPC homing in the course of sepsis.

Electronic supplementary material

The online version of this article (10.1186/s12950-018-0186-7) contains supplementary material, which is available to authorized users.

Exosomes from patients with septic shock convey miRNAs related to inflammation and cell cycle regulation: new signaling pathways in sepsis?

Background

Exosomes isolated from plasma of patients with sepsis may induce vascular apoptosis and myocardial dysfunction by mechanisms related to inflammation and oxidative stress. Despite previous studies demonstrating that these vesicles contain genetic material related to cellular communication, their molecular cargo during sepsis is relatively unknown. In this study, we evaluated the presence of microRNAs (miRNAs) and messenger RNAs (mRNAs) related to inflammatory response and redox metabolism in exosomes of patients with septic shock.

Methods

Blood samples were collected from 24 patients with septic shock at ICU admission and after 7 days of treatment. Twelve healthy volunteers were used as control subjects. Exosomes were isolated by ultracentrifugation, and their miRNA and mRNA content was evaluated by qRT-PCR array.

Results

As compared with healthy volunteers, exosomes from patients with sepsis had significant changes in 65 exosomal miRNAs. Twenty-eight miRNAs were differentially expressed, both at enrollment and after 7 days, with similar kinetics (18 miRNAs upregulated and 10 downregulated). At enrollment, 35 differentially expressed miRNAs clustered patients with sepsis according to survival. The pathways enriched by the miRNAs of patients with sepsis compared with control subjects were related mostly to inflammatory response. The comparison of miRNAs from patients with sepsis according to hospital survival demonstrated pathways related mostly to cell cycle regulation. At enrollment, sepsis was associated with significant increases in the expression of mRNAs related to redox metabolism (myeloperoxidase, 64-fold; PRDX3, 2.6-fold; SOD2, 2.2-fold) and redox-responsive genes (FOXM1, 21-fold; SELS, 16-fold; GLRX2, 3.4-fold). The expression of myeloperoxidase mRNA remained elevated after 7 days (65-fold).

Conclusions

Exosomes from patients with septic shock convey miRNAs and mRNAs related to pathogenic pathways, including inflammatory response, oxidative stress, and cell cycle regulation. Exosomes may represent a novel mechanism for intercellular communication during sepsis.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2003-3) contains supplementary material, which is available to authorized users.

Exosomes from Endothelial Progenitor Cells Improve the Outcome of a Murine Model of Sepsis

Microvascular dysfunction leads to multi-organ failure and mortality in sepsis. Our previous studies demonstrated that administration of exogenous endothelial progenitor cells (EPCs) confers protection in sepsis as evidenced by reduced vascular leakage, improved organ function, and increased survival. We hypothesize that EPCs protect the microvasculature through the exosomes-mediated transfer of microRNAs (miRNAs). Mice were rendered septic by cecal ligation and puncture (CLP), and EPC exosomes were administered intravenously at 4 hr after CLP. EPC exosomes treatment improved survival, suppressing lung and renal vascular leakage, and reducing liver and kidney dysfunction in septic mice. EPC exosomes attenuated sepsis-induced increases in plasma levels of cytokines and chemokine. Moreover, we determined miRNA contents of EPC exosomes with next-generation sequencing and found abundant miR-126-3p and 5p. We demonstrated that exosomal miR-126-5p and 3p suppressed LPS-induced high mobility group box 1 (HMGB1) and vascular cell adhesion molecule 1 (VCAM1) levels, respectively, in human microvascular endothelial cells (HMVECs). Inhibition of microRNA-126-5p and 3p through transfection with microRNA-126-5p and 3p inhibitors abrogated the beneficial effect of EPC exosomes. The inhibition of exosomal microRNA-126 failed to block LPS-induced increase in HMGB1 and VCAM1 protein levels in HMVECs and negated the protective effect of exosomes on sepsis survival. Thus, EPC exosomes prevent microvascular dysfunction and improve sepsis outcomes potentially through the delivery of miR-126.

Intravenous administration of xenogenic adipose-derived mesenchymal stem cells (ADMSC) and ADMSC-derived exosomes markedly reduced brain infarct volume and preserved neurological function in rat after acute ischemic stroke

We tested the hypothesis that combined xenogenic (from mini-pig) adipose-derived mesenchymal stem cell (ADMSC) and ADMSC-derived exosome therapy could reduce brain-infarct zone (BIZ) and enhance neurological recovery in rat after acute ischemic stroke (AIS) induced by 50-min left middle cerebral artery occlusion. Adult-male Sprague-Dawley rats (n = 60) were divided equally into group 1 (sham-control), group 2 (AIS), group 3 [AIS-ADMSC (1.2×106 cells)], group 4 [AIS-exosome (100μg)], and group 5 (AIS-exosome-ADMSC). All therapies were provided intravenously at 3h after AIS procedure. BIZ determined by histopathology (by day-60) and brain MRI (by day-28) were highest in group 2, lowest in group 1, higher in groups 3 and 4 than in group 5, but they showed no difference between groups 3 and 4 (all p < 0.0001). By day-28, sensorimotor functional results exhibited an opposite pattern to BIZ among the five groups (p < 0.005). Protein expressions of inflammatory (inducible nitric oxide synthase/tumor necrosis factor-α/nuclear factor-κB/interleukin-1β/matrix metalloproteinase-9/plasminogen activator inhibitor-1/RANTES), oxidative-stress (NOX-1/NOX-2/oxidized protein), apoptotic (caspase-3/ Poly-ADP-ribose polymerase), and fibrotic (Smad3/transforming growth factor-β) biomarkers, and cellular expressions of brain-damaged (γ-H2AX+/ XRCC1-CD90+/p53BP1-CD90+), inflammatory (CD11+/CD68+/glial fibrillary acid protein+) and brain-edema (aquaporin-4+) markers showed a similar pattern of BIZ among the groups (all n < 0.0001). In conclusion, xenogenic ADMSC/ADMSC-derived exosome therapy was safe and offered the additional benefit of reducing BIZ and improving neurological function in rat AIS.

Cell therapy for the treatment of sepsis and acute respiratory distress syndrome

Sepsis and acute respiratory distress syndrome (ARDS) are life threating diseases with high mortality and morbidity in all the critical care units around the world. After decades of research, and numerous pre-clinical and clinical trials, sepsis and ARDS remain without a specific and effective pharmacotherapy and essentially the management remains supportive. In the last years cell therapies gained potential as a therapeutic treatment for ARDS and sepsis. Based on numerous pre-clinical studies, there is a growing evidence of the potential benefits of cell based therapies for the treatment of sepsis and ARDS. Several cell types are used in the last years for the treatment of both syndromes showing high efficiency. Embryonic stem cells (ESC), multipotent stem (or stromal) cells (MSC) and epithelial progenitors cells (EpPC) have been used for both diseases. Nowadays, the major part of the pre-clinical studies are using MSC, however other relevant groups are also using induced pluripotent stem cells (iPSC) for the treatment of both syndromes and alveolar type II cells for ARDS treatment. Numerous questions need further study including: determining the best source for the progenitor cells isolation, their large scale production and cryopreservation. Also, the heterogeneity of patients with sepsis and ARDS is massive, and establish a target population or the stratification of the patients will help us to determine better the therapeutic effect of these cell therapies. In this review we are going to describe briefly the different cell types, their potential sources and characteristics and mechanism of action. Here, also we elucidate the results of several pre-clicinical and clinical studies in ARDS and in sepsis and the future directions of these studies.

Detection of intrathrombotic endothelial progenitor cells and its application to thrombus age estimation in a murine deep vein thrombosis model

Endothelial progenitor cells (EPCs), a newly identified cell type, are bone marrow-derived progenitor cells that co-express stem cell markers and Flk-1 (one of the receptors for vascular endothelial growth factor). In this study, double-color immunofluorescence analysis was performed using anti-CD34 and anti-Flk-1 antibodies in order to examine the time-dependent intrathrombotic appearance of EPCs, using the thrombi of DVT model mice with different thrombus ages (1-21 days). In thrombus cross-section specimens with an age of less than 3 days, CD34+/Flk-1+ EPCs were not detected. EPCs were initially observed in wounds aged 5 days, and their number was increased in thrombi with the advance of thrombus ages. The number of EPCs was the largest in the 10-day thrombus. Moreover, all 15 samples aged 7-14 days had an EPC number of more than 10, and, in 9 of them, the number of intrathrombotic EPCs was over 20. In contrast, in all thrombus samples aged 21 days, the number of intrathrombotic EPCs was less than 20. However, in three of them, the intrathrombotic EPC number was ≥ 10. These observations suggested that an intrathrombotic EPC number exceeding 20 would indicate a thrombus age of approximately 7-14 days.

Progranulin Plays a Central Role in Host Defense during Sepsis by Promoting Macrophage Recruitment

RATIONALE

Progranulin, a widely expressed protein, has multiple physiological functions. The functional role of progranulin in the host response to sepsis remains unknown.

OBJECTIVES

To assess the role of progranulin in the host response to sepsis.

METHODS

Effects of progranulin on host response to sepsis were determined.

MEASUREMENTS AND MAIN RESULTS

Progranulin concentrations were significantly elevated in adult (n = 74) and pediatric (n = 26) patients with sepsis relative to corresponding healthy adult (n = 36) and pediatric (n = 17) control subjects, respectively. By using a low-lethality model of nonsevere sepsis, we observed that progranulin deficiency not only increased mortality but also decreased bacterial clearance during sepsis. The decreased host defense to sepsis in progranulin-deficient mice was associated with reduced macrophage recruitment, with correspondingly impaired chemokine CC receptor ligand 2 (CCL2) production in peritoneal lavages during the early phase of sepsis. Progranulin derived from hematopoietic cells contributed to host defense in sepsis. Therapeutic administration of recombinant progranulin not only rescued impaired host defense in progranulin-deficient mice after nonsevere sepsis but also protected wild-type mice against a high-lethality model of severe sepsis. Progranulin-mediated protection against sepsis was closely linked to improved peritoneal macrophage recruitment. In addition, CCL2 treatment of progranulin-deficient mice improved survival and decreased peritoneal bacterial loads during sepsis, at least in part through promotion of peritoneal macrophage recruitment.

CONCLUSIONS

This proof-of-concept study supports a central role of progranulin-dependent macrophage recruitment in host defense to sepsis, opening new opportunities to host-directed therapeutic strategy that manipulate host immune response in the treatment of sepsis.