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Sepsis is a potentially fatal syndrome related to severe systemic inflammation developed by infection. Despite different antimicrobial therapies, morbidity and mortality rates remain high. Herbs along with cell therapy have been introduced as a promising option to improve the symptoms of sepsis. The present study aimed to evaluate the therapeutic effect of simultaneous administration of thyme essential oil (TEO) and endothelial progenitor stem cells (EPCs) on lipopolysaccharide (LPS)‐induced sepsis in C57BL/6 mice. Sepsis was induced in C57Bl/6J mice by intraperitoneal injection of LPS, followed 2 h later by an intravenous injection of EPCs or oral administration of TEO or simultaneous administration of TEO and EPCs. After 10 days, the complete blood cell, renal and liver factors, serum levels of inflammatory cytokines, and angiogenic factors were measured. Simultaneous treatment with EPCs and TEO significantly increased the survival of mice with sepsis and modulated the inflammatory response by reducing the serum levels of pro‐inflammatory cytokines. Moreover, this treatment significantly reduced the level of white blood cells and neutrophils and increased the number of red blood cells, the percentage of hematocrit, and hemoglobin. The combination of TEO with EPCs decreased organ injuries and was assessed by lower levels of the liver enzymes alanine aminotransferase and aspartate aminotransferase compared to the sepsis group. Administration of EPCs and TEO also significantly improved angiogenic factors, lung function, and toll‐like receptor 4 expression. EPCs in combination with TEO increase survival in the LPS‐induced sepsis mice model by acting on several targets. Thus, the combination of TEO with EPCs can be a feasible approach for the future clinical treatment and control of sepsis. [ABSTRACT FROM AUTHOR]

This research explores the role of microRNA in senescence of human endothelial progenitor cells (EPCs) induced by replication. Hsa‐miR‐134‐5p was found up‐regulated in senescent EPCs where overexpression improved angiogenic activity. Hsa‐miR‐134‐5p, which targeted transforming growth factor β‐activated kinase 1‐binding protein 1 (TAB1) gene, down‐regulated TAB1 protein, and inhibited phosphorylation of p38 mitogen‐activated protein kinase (p38) in hsa‐miR‐134‐5p‐overexpressed senescent EPCs. Treatment with siRNA specific to TAB1 (TAB1si) down‐regulated TAB1 protein and subsequently inhibited p38 activation in senescent EPCs. Treatment with TAB1si and p38 inhibitor, respectively, showed angiogenic improvement. In parallel, transforming growth factor Beta 1 (TGF‐β1) was down‐regulated in hsa‐miR‐134‐5p‐overexpressed senescent EPCs and addition of TGF‐β1 suppressed the angiogenic improvement. Analysis of peripheral blood mononuclear cells (PBMCs) disclosed expression levels of hsa‐miR‐134‐5p altered in adult life, reaching a peak before 65 years, and then falling in advanced age. Calculation of the Framingham risk score showed the score inversely correlates with the hsa‐miR‐134‐5p expression level. In summary, hsa‐miR‐134‐5p is involved in the regulation of senescence‐related change of angiogenic activity via TAB1‐p38 signalling and via TGF‐β1 reduction. Hsa‐miR‐134‐5p has a potential cellular rejuvenation effect in human senescent EPCs. Detection of human PBMC‐derived hsa‐miR‐134‐5p predicts cardiovascular risk. [ABSTRACT FROM AUTHOR]

This study explores the impact of senescence on autocrine C‐C motif chemokine ligand 5 (CCL5) in human endothelial progenitor cell (EPCs), addressing the poorly understood decline in number and function of EPCs during ageing. We examined the effects of replication‐induced senescence on CCL5/CCL5 receptor (CCR5) signalling and angiogenic activity of EPCs in vitro and in vivo. We also explored microRNAs controlling CCL5 secretion in senescent EPCs, its impact on EPC angiogenic activity, and validated our findings in humans. CCL5 secretion and CCR5 levels in senescent EPCs were reduced, leading to attenuated angiogenic activity. CCL5 enhanced EPC proliferation via the CCR5/AKT/P70S6K axis and increased vascular endothelial growth factor (VEGF) secretion. Up‐regulation of miR‐409 in senescent EPCs resulted in decreased CCL5 secretion, inhibiting the angiogenic activity, though these negative effects were counteracted by the addition of CCL5 and VEGF. In a mouse hind limb ischemia model, CCL5 improved the angiogenic activity of senescent EPCs. Analysis involving 62 healthy donors revealed a negative association between CCL5 levels, age and Framingham Risk Score. These findings propose CCL5 as a potential biomarker for detection of EPC senescence and cardiovascular risk assessment, suggesting its therapeutic potential for age‐related cardiovascular disorders. [ABSTRACT FROM AUTHOR]

Oxidized low‐density lipoprotein (ox‐LDL) causes dysfunction of endothelial progenitor cells (EPCs), and we recently reported that 14‐3‐3‐η can attenuate the damage triggered by ox‐LDL in EPCs. However, the molecular mechanisms by which 14‐3‐3‐η protects EPCs from the damage caused by ox‐LDL are not fully understood. In this study, we observed that the expression of 14‐3‐3‐η and BCL‐2 were downregulated in ox‐LDL‐treated EPCs. Overexpression of 14‐3‐3‐η in ox‐LDL‐treated EPC significantly increased BCL‐2 level, while knockdown of BCL‐2 reduced 14‐3‐3‐η expression and mitigated the protective effect of 14‐3‐3‐η on EPCs. In addition, we discovered that 14‐3‐3‐η colocalizes and interacts with BCL‐2 in EPCs. Taken together, these data suggest that 14‐3‐3‐η protects EPCs from ox‐LDL‐induced damage by its interaction with BCL‐2. [ABSTRACT FROM AUTHOR]

Nonunion and segmental bone defects are complex issues in orthopedic trauma. The use of endothelial progenitor cells (EPCs), as part of a cell‐based therapy for bone healing is a promising approach. In preclinical studies, culture medium (CM) is commonly used to deliver EPCs to the defect site, which has the potential for immunogenicity in humans. The goal of this study was to find an effective and clinically translatable delivery medium for EPCs. Accordingly, this study compared EPCs delivered in CM, phosphate‐buffered saline (PBS), platelet‐poor plasma (PPP), and platelet‐rich plasma (PRP) in a rat model of femoral critical‐size defects. Fischer 344 rats (n = 35) were divided into six groups: EPC+CM, EPC+PBS, EPC+PPP, EPC+PRP, PPP alone, and PRP alone. A 5 mm mid‐diaphyseal defect was created in the right femur and stabilized with a miniplate. The defect was filled with a gelatin scaffold impregnated with the corresponding treatment. Radiographic, microcomputed tomography and biomechanical analyses were performed. Overall, regardless of the delivery medium, groups that received EPCs had higher radiographic scores and union rates, higher bone volume, and superior biomechanical properties compared to groups treated with PPP or PRP alone. There were no significant differences in any outcomes between EPC subgroups or between PPP and PRP alone. These results suggest that EPCs are effective in treating segmental defects in a rat model of critical‐size defects regardless of the delivery medium used. Consequently, PBS could be the optimal medium for delivering EPCs, given its low cost, ease of preparation, accessibility, noninvasiveness, and nonimmunogenic properties. [ABSTRACT FROM AUTHOR]

One of the major obstacles to the effective application of vascularized fruit is an insufficient understanding of the relationship between the microenvironment and neovascular homeostasis. The role of extracellular matrix stiffness in regulating the structural and functional stability of neovascularization has not yet been elucidated. This study explored the effects of matrix stiffness on neovascular homeostasis in nude mice. Dextran hydrogels with three different stiffnesses were separately combined with mouse bone marrow‐derived endothelial progenitor cells (EPCs) and subcutaneously implanted into the backs of nude mice. After 14 days, neovascular homeostasis indicators in the different groups were measured. Cell autophagy levels were evaluated, and inhibitor assays were performed to explore the underlying mechanism. New blood vessels were generated in the three stiffnesses of the EPC‐loaded dextran hydrogels 14 days after implantation. The newly formed vessels tended to have better structural stability in softer hydrogels. Endothelial function markers, such as endothelial nitric oxide synthase and E‐selectin, were downregulated as the matrix stiffness increased. Furthermore, we found that cell autophagy levels decreased in stiffer matrices, and autophagy inhibition attenuated neovascular homeostasis. A soft matrix is conducive to maintaining neovascular homeostasis through autophagy in nude mice. [ABSTRACT FROM AUTHOR]

Formation of functional and perfusable vascular network is critical to ensure the long‐term survival and functionality of the engineered tissue tracheae after transplantation. However, the greatest challenge in tracheal‐replacement therapy is the promotion of tissue regeneration by rapid graft vascularization. Traditional prevascularization methods for tracheal grafts typically utilize omentum or muscle flap wrapping, which requires a second operation; vascularized segment tracheal orthotopic transplantation in one step remains difficult. This study proposes a method to construct a tissue‐engineered tracheal graft, which directly forms the microvascular network after orthotopic transplantation in vivo. The focus of this study was the preparation of a hybrid tracheal graft that is non‐immunogenic, has good biomechanical properties, supports cell proliferation, and quickly vascularizes. The results showed that vacuum‐assisted decellularized trachea‐polycaprolactone hybrid scaffold could match most of the above requirements as closely as possible. Furthermore, endothelial progenitor cells (EPCs) were extracted and used as vascularized seed cells and seeded on the surfaces of hybrid grafts before and during the tracheal orthotopic transplantation. The results showed that the microvascularized tracheal grafts formed maintained the survival of the recipient, showing a satisfactory therapeutic outcome. This is the first study to utilize EPCs for microvascular construction of long‐segment trachea in one‐step; the approach represents a promising method for microvascular tracheal reconstruction. [ABSTRACT FROM AUTHOR]

Severe trauma and hemorrhaging are often accompanied by delayed cutaneous wound healing. Soybean isoflavone is a natural phytoestrogen that has attracted great attention due to its protective effects against various injuries. Endothelial progenitor cells (EPCs) are precursor cells with directional differentiation characteristics. This study is to determine whether genistein (GEN), an isoflavone in soybean products, benefits wound healing in hemorrhagic shock (HS) rats by promoting EPC homing and to investigate the underlying mechanisms. In this study, it is found that GEN promotes skin wound healing in HS rats, which is due at least partly to the mobilization of endogenous EPCs to the injury site via angiotensin II (Ang‐II), stromal cell‐derived factor‐1alpha (SDF‐1α), and transforming growth factor beta(TGF‐β) signaling. [ABSTRACT FROM AUTHOR]

We explored the roles of hsa‐microRNA (miR)‐409‐3p in senescence and signalling mechanism of human endothelial progenitor cells (EPCs). Hsa‐miR‐409‐3p was found upregulated in senescent EPCs. Overexpression of miRNA mimics in young EPCs inhibited angiogenesis. In senescent EPCs, compared to young EPCs, protein phosphatase 2A (PP2A) was downregulated, with activation of p38/JNK by phosphorylation. Young EPCs treated with siPP2A caused inhibited angiogenesis with activation of p38/JNK, similar to findings in senescent EPCs. Time series analysis showed, in young EPCs treated with hsa‐miR‐409‐3p mimics, PP2A was steadily downregulated for 72 h, while p38/JNK was activated with a peak at 48 hours. The inhibited angiogenesis of young EPCs after miRNA‐409‐3p mimics treatment was reversed by the p38 inhibitor. The effect of hsa‐miR‐409‐3p on PP2A signalling was attenuated by exogenous VEGF. Analysis of human peripheral blood mononuclear cells (PBMCs) obtained from healthy people revealed hsa‐miR‐409‐3p expression was higher in those older than 65 years, compared to those younger than 30 years, regardless of gender. In summary, hsa‐miR‐409‐3p was upregulated in senescent EPCs and acted as a negative modulator of angiogenesis via targeting protein phosphatase 2 catalytic subunit alpha (PPP2CA) gene and regulating PP2A/p38 signalling. Data from human PBMCs suggested hsa‐miR‐409‐3p a potential biomarker for human ageing. [ABSTRACT FROM AUTHOR]

Objective: The long‐term survival of kidney transplant patients has substantially improved. However, there is a higher risk for cardiovascular events after transplantation, partly due to immunosuppression. A diminished number of endothelial progenitor cells (EPCs), which play an important role in angiogenesis and the repair of endothelial damage, are associated with an increased cardiovascular risk. The aim of this study was to evaluate whether kidney transplantation affects EPCs in women. Methods: Twenty‐four healthy women and 22 female kidney transplant recipients were recruited. The ratio of angiogenic and non‐angiogenic circulating progenitor cells (CPCs) was determined by multicolor flow cytometry and related to clinical parameters. Cord blood‐derived endothelial colony‐forming cells (ECFCs), a proliferative subgroup of endothelial progenitor cells, were treated with pooled sera from transplant patients or healthy controls and tested for their functional integrity using in vitro models. Results: Kidney transplant recipients displayed a reduced ratio of angiogenic and non‐angiogenic CPCs compared to healthy controls. Differences were especially pronounced in premenopausal women. Exposure to sera of transplanted women led to a significant impairment of ECFC proliferation, migration, and angiogenesis ability. Conclusions: Alterations of EPC populations may contribute to the higher cardiovascular risks after organ transplantation and should be considered in therapeutic strategies. [ABSTRACT FROM AUTHOR]

In patients with ANCA‐associated vasculitis, interactions between neutrophils and endothelial cells cause endothelial damage and imbalance. Endothelial colony‐forming cells (ECFCs) represent a cellular population of the endothelial lineage with proliferative capacity and vasoreparative properties. This study aimed to evaluate the angiogenic capacity of ECFCs of patients with granulomatosis with polyangiitis (GPA). The ECFCs of 13 patients with PR3‐positive GPA and 14 healthy controls were isolated and characterized using fluorescence‐activated cell sorting, capillary tube formation measurement, scratching assays and migration assays with and without plasma stimulation. Furthermore, three patients with active disease underwent post‐treatment recollection of ECFCs for longitudinal evaluation. The ECFCs from the patients and controls showed similar capillary structure formation. However, the ECFCs from the patients with inactive GPA exhibited early losses of angiogenic capacity. Impairments in the migration capacities of the ECFCs were also observed in patients with GPA and controls (12th h, p = 0.05). Incubation of ECFCs from patients with GPA in remission with plasma from healthy controls significantly decreased migration capacity (p = 0.0001). Longitudinal analysis revealed that treatment significantly lowered ECFC migration rates. This study revealed that ECFCs from the patients with PR3‐positive GPA in remission demonstrated early losses of tube formation and reduced migration capacity compared to those of the healthy controls, suggesting impairment of endothelial function. [ABSTRACT FROM AUTHOR]

Aims: Endothelial progenitor cells (EPCs) function as the angiogenic switch of many physiological and pathological conditions. We aimed to investigate the effects of Porphyromonas gingivalis lipopolysaccharide on the angiogenic capacity of EPCs and delineate the underlying mechanisms. Materials and Methods: EPCs were isolated from human umbilical blood. CCK‐8 assay was undertaken to analyze the cell viability. The migration and tube formation capacity were assessed by wound healing and tube formation, respectively. The protein expression of Akt/p‐Akt, endothelial nitric oxide synthase (eNOS)/p‐eNOS, and Forkhead box O1 (FoxO1)/p‐FoxO1 was determined by Western blot. The intracellular localization of FoxO1 was evaluated by immunofluorescent staining. Results: P. gingivalis LPS at 10 μg/ml significantly increased the viability (10.9 ± 2.9%), migration (16.3 ± 3.1%), and tube formation (38.6 ± 5.5%) of EPCs, along with increased phosphorylation of Akt, eNOS, and FoxO1. Mechanistically, Akt inhibition by specific inhibitor wortmannin and FoxO1 forced expression by adenovirus transfection in EPCs markedly attenuated the P. gingivalis LPS‐induced eNOS activation, tube formation, and migration. Moreover, P. gingivalis LPS‐induced phosphorylation and nuclear exclusion of FoxO1 were blunted by Akt inhibition. Conclusions: The present study suggests that P. gingivalis LPS could affect the angiogenic function of EPCs through the Akt/FoxO1 signaling. The current findings may shed light on the clinical association of periodontitis with aberrant angiogenesis seen in atherosclerotic plaque rupture. [ABSTRACT FROM AUTHOR]

Preeclampsia, a pregnancy‐related hypertensive disorder, is associated with endothelial dysfunction and increased cardiovascular risk of the offspring in adulthood. In preeclampsia, endothelial colony‐forming cells (ECFC) are reduced in number and function. Recently, we have shown that miR‐1270, which is involved in cancer in vitro proliferation, migration, and tumor progression, is downregulated in fetal ECFC from preeclamptic pregnancies. We now hypothesize that miR‐1270 dysregulation contributes to vascular endothelial dysfunction occurring after preeclampsia via ATM (ataxia telangiectasia mutated) overexpression, the key kinase of DNA damage repair. Here, we show that miR‐1270 silencing in normal ECFC and downregulation in preeclamptic ECFC are accompanied by an increase in the expression levels of ATM. Furthermore, ATM activation correlates with upregulated tyrosine kinase Src leading to phosphorylation and internalization of VE‐cadherin (vascular endothelial‐cadherin) which subsequently compromises endothelial barrier permeability and morphodynamic cell parameters. Treatment with specific ATM inhibitors reveals a novel role of ATM upstream of tyrosine kinase Src activation. Subsequently, Src phosphorylation and internalization of VE‐cadherin compromise endothelial barrier permeability. Our findings suggest that downregulation of miR‐1270 contributes to impaired ECFC function via the associated ATM overexpression, which further identifies ATM as a novel and critical factor for ECFC defects in preeclampsia. Our study provides new insights into the understanding of ECFC impairment associated with cardiovascular risk in preeclamptic offspring and identifies potential novel therapeutic targets. [ABSTRACT FROM AUTHOR]

Endothelial progenitor cells (EPCs) contribute to de novo angiogenesis, tissue regeneration, and remodeling. Interleukin 10 (IL‐10), an anti‐inflammatory cytokine that primarily signals via STAT3, has been shown to drive EPC recruitment to injured tissues. Our previous work demonstrated that overexpression of IL‐10 in dermal wounds promotes regenerative tissue repair via STAT3‐dependent regulation of fibroblast‐specific hyaluronan synthesis. However, IL‐10's role and specific mode of action on EPC recruitment, particularly in dermal wound healing and neovascularization in both normal and diabetic wounds, remain to be defined. Therefore, inducible skin‐specific STAT3 knockdown mice were studied to determine IL‐10's impact on EPCs, dermal wound neovascularization and healing, and whether it is STAT3‐dependent. We show that IL‐10 overexpression significantly elevated EPC counts in the granulating wound bed, which was associated with robust capillary lumen density and enhanced re‐epithelialization of both control and diabetic (db/db) wounds at day 7. We noted increased VEGF and high C‐X‐C motif chemokine 12 (CXCL12) levels in wounds and a favorable CXCL12 gradient at day 3 that may support EPC mobilization and infiltration from bone marrow to wounds, an effect that was abrogated in STAT3 knockdown wounds. These findings were supported in vitro. IL‐10 promoted VEGF and CXCL12 synthesis in primary murine dermal fibroblasts, with blunted VEGF expression upon blocking CXCL12 in the media by antibody binding. IL‐10‐conditioned fibroblast media also significantly promoted endothelial sprouting and network formation. In conclusion, these studies demonstrate that overexpression of IL‐10 in dermal wounds recruits EPCs and leads to increased vascular structures and faster re‐epithelialization. [ABSTRACT FROM AUTHOR]

Background Information: Endothelial progenitor cells (EPCs) can exert angiogenic effects by a paracrine mechanism, where exosomes work as an important mediator. Recent studies reported functional expression of toll‐like receptor (TLR) 4 on human EPCs and dose‐dependent effects of lipopolysaccharide (LPS) on EPC angiogenic properties. To study the effects of TLR4/LPS signaling on EPC‐derived exosomes (Exo) and clarify the mechanism, we investigated the role of LPS on exosomes secretion from human EPCs and tested their anti‐oxidation/senescence functions. We employed the inhibitors of the plasma membrane Ca2+‐ATPase (PMCA), endoplasmic reticulum Ca2+‐ATPase (ERCA), PLC‐IP3 pathway and store‐operated calcium entry to assess the effects of LPS on EPC intracellular calcium signalings which critical for exosome secretion. Results: LPS induced the release of Exo in a TLR4‐dependent manner in vitro, which effect can be partly abrogated by an membrane‐permeable IP 3 R antagonist, 2‐aminoethyl diphenylborinate (2‐APB), but not PLC inhibitor, U‐73122. The LPS can significantly delay the fallback of [Ca2+]i after isolating the cellular PMCA activity, and disturb PMCA 1/4 expression. The distribution of elevated intracellular calcium seemed coincident with the development of the multivesicular bodies (MVBs). furthermore, the anti‐oxidation/senescence properties of LPS‐induced Exo were validated by the senescence‐associated β‐galactosidase activity assay and reactive oxygen species (ROS) related H2DCF‐DA assay. Conclusions: The mechanism of PMCA downregulation and IP3R‐dependent ER Ca2+ release may contribute to the pro‐exosomal effects of LPS on EPCs. Significance: This study provides new insights into the potential role of LPS/TLR4 pathway in regulating EPC‐derived exosomes, which may help to develop some feasible approach to manipulate the Exo secretion and promote the clinical application of EPCs therapy in future. [ABSTRACT FROM AUTHOR]

Background: Accumulating evidences indicate that periodontitis is closely associated with endothelial dysfunction. Trimethylamine-N-oxide (TMAO), a harmful microbiota generated metabolite, has been implicated as a nontraditional risk factor for impaired endothelial function. However, whether increased circulating levels of TMAO in periodontitis patients induces endothelial dysfunction remains unknown.Methods: Patients with periodontitis and periodontally healthy controls were enrolled. Periodontal inflamed surface area (PISA) was calculated to assess the inflammatory burden posed by periodontitis. The circulating TMAO was measured by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). Vascular endothelial function including peripheral endothelial progenitor cells (EPCs), brachial arterial flow-mediated vasodilation (FMD), and brachial-ankle pulse wave velocity (baPWV) were assessed. We also isolated and cultured EPCs from participants' peripheral blood to investigate the effect of TMAO on EPC functions in vitro.Results: One hundred and twenty two patients with Stage III-IV periodontitis and 81 healthy controls were included. Patients with periodontitis presented elevated TMAO (P = 0.002), lower EPCs (P = 0.025), and declined FMD levels (P = 0.005). The TMAO concentrations were correlated with reduced circulating EPCs and FMD levels. Moreover, TMAO can injury EPCs function in vitro, and may induce cell pyroptosis via Bax/caspase-3/GSDME pathway.Conclusions: The present study demonstrates for the first time that circulating TMAO levels are increased in patients with Stage III-IV periodontitis, and correlated with vascular endothelial dysfunction. These findings may provide a novel insight into the mechanism of vascular endothelial dysfunction in patient with periodontitis via TMAO-downregulated EPC functions. [ABSTRACT FROM AUTHOR]

It was shown that endothelial progenitor cells (EPCs) have bidirectional differentiation potential and thus perform different biological functions. The purpose of this study was to investigate the effects of slight up‐regulation of the Kir2.1 channel on EPC transdifferentiation and the potential mechanism on cell function and transformed cell type. First, we found that the slight up‐regulation of Kir2.1 expression promoted the expression of the stem cell stemness factors ZFX and NS and inhibited the expression of senescence‐associated β‐galactosidase. Further studies showed the slightly increased expression of Kir2.1 could also improve the expression of pericyte molecular markers NG2, PDGFRβ and Desmin. Moreover, adenovirus‐mediated Kir2.1 overexpression had an enhanced contractile response to norepinephrine of EPCs. These results suggest that the up‐regulated expression of the Kir2.1 channel promotes EPC transdifferentiation into a pericyte phenotype. Furthermore, the mechanism of EPC transdifferentiation to mesenchymal cells (pericytes) was found to be closely related to the channel functional activity of Kir2.1 and revealed that this channel could promote EPC EndoMT by activating the Akt/mTOR/Snail signalling pathway. Overall, this study suggested that in the early stage of inflammatory response, regulating the Kir2.1 channel expression affects the biological function of EPCs, thereby determining the maturation and stability of neovascularization. [ABSTRACT FROM AUTHOR]

Valve disease and particularly calcific aortic valve disease (CAVD) and diabetes (DM) are progressive diseases constituting a global health burden for all aging societies (Progress in Cardiovascular Diseases. 2014;56(6):565: Circulation Research. 2021;128(9):1344). Compared to non-diabetic individuals (The Lancet. 2008;371(9626):1800: The American Journal of Cardiology. 1983;51(3):403: Journal of the American College of Cardiology. 2017;69(12):1523), the diabetic patients have a significantly greater propensity for cardiovascular disorders and faster degeneration of implanted bioprosthetic aortic valves. Previously, using an original experimental model, the diabetic-hyperlipemic hamsters, we have shown that the earliest alterations induced by these conditions occur at the level of the aortic valves and, with time these changes lead to calcifications and CAVD. However, there are no pharmacological treatments available to reverse or retard the progression of aortic valve disease in diabetes, despite the significant advances in the field. Therefore, it is critical to uncover the mechanisms of valve disease progression, find biomarkers for diagnosis and new targets for therapies. This review aims at presenting an update on the basic research in CAVD in the context of diabetes. We provide an insight into the accumulated data including our results on diabetes-induced progressive cell and molecular alterations in the aortic valve, new potential biomarkers to assess the evolution and therapy of the disease, advancement in targeted nanotherapies, tissue engineering and the potential use of circulating endothelial progenitor cells in CAVD. [ABSTRACT FROM AUTHOR]

Plasmacytoid dendritic cells (pDCs) play a key role in the initiation and amplification of systemic lupus erythematosus (SLE)‐associated vascular injury. In this study, we found that dsDNA induced dose‐ and time‐dependent increase in IFN‐α and Toll‐like receptor 7 (TLR7), TLR9 and IRF7 expression in pDCs. Co‐cultured circulating endothelial cells (ECs) with activated pDCs significantly decreased proliferation, tube formation and migration in ECs. The elevated level of cellular IFN‐α increased cell adhesion, promoted cell apoptosis, induced cell senescence and arrested cells at G0/G1 phase of endothelial progenitor cells (EPCs). Additionally, the co‐culture system activated MAPK and inactivated PI3K. Pristane was used to establish a in vivo SLE‐like mouse model. Importantly, we showed that INF‐α‐neutralizing antibody (IFN‐α‐NA) rescued all the changes induced by IFN‐α in vitro and prevented vascular injury in pristane‐induced SLE model in vivo. In conclusion, we confirmed that activated pDCs promoted vascular damage and the dysfunction of ECs/EPCs via IFN‐α production. IFN‐α‐neutralizing antibody may be a clinical implication for preventing vascular injury. PI3K signalling and AMPK signalling were associated with SLE‐associated vascular functions. [ABSTRACT FROM AUTHOR]

The importance of flow shear stress (SS) on the differentiation of endothelial progenitor cells (EPCs) has been demonstrated in various studies. Cholesterol retention and microRNA regulation have been also proposed as relevant factors involved in this process, though evidence regarding their regulatory roles in the differentiation of EPCs is currently lacking. In the present study on high shear stress (HSS)‐induced differentiation of EPCs, we investigated the importance of ATP‐binding cassette transporter 1 (ABCA1), an important regulator in cholesterol efflux, and miR‐25‐5p, a potential regulator of endothelial reconstruction. We first revealed an inverse correlation between miR‐25‐5p and ABCA1 expression levels in EPCs under HSS treatment; their direct interaction was subsequently validated by a dual‐luciferase reporter assay. Further studies using flow cytometry and quantitative polymerase chain reaction demonstrated that both miR‐25‐5p overexpression and ABCA1 inhibition led to elevated levels of specific markers of endothelial cells, with concomitant downregulation of smooth muscle cell markers. Finally, knockdown of ABCA1 in EPCs significantly promoted tube formation, which confirmed our conjecture. Our current results suggest that miR‐25‐5p might regulate the differentiation of EPCs partially through targeting ABCA1, and such a mechanism might account for HSS‐induced differentiation of EPCs. [ABSTRACT FROM AUTHOR]

A major barrier in the multi‐purpose use of implantable materials is an incomplete integration with surrounding tissues, causing foreign body reactions, such as fibrous encapsulation and chronic inflammation. From its viewpoint, a universal method is suggested for cloaking any kind of substrate in specific cell‐made extracellular matrices (ECMs) via robust linkages for delivery of therapeutic cells. In addition, the feasibility of ECM‐coated substrates as endothelial progenitor cells (EPCs)‐laden coronary stent platform for endovascular implantation is investigated. Characteristics and stability of cell‐secreted ECMs anchored on a substrate are evaluated, and structural and componential features are revealed similar to those of native ECMs, with enough strength to enable practical uses. The in vitro experiments demonstrated that the ECM coating effectively supports the adhesion, proliferation, and viability of EPCs and has selectively opposite effects on smooth muscle cells. The in vivo experiments using a porcine coronary model supports that ECM‐coated stents enable endothelial regeneration and inhibit neointimal growth, and the cell‐laden form is more effective than other stents. These results will allow the preparation of tissue‐integrating materials containing cellular microenvironments and safely coat surfaces with cells to enable long‐term implantation and the continuous managing of chronic diseases. [ABSTRACT FROM AUTHOR]

Endothelial progenitor cells (EPCs) are precursor cells of vascular endothelial cells, which are widely involved in the pathological process of cardiovascular diseases. EPCs apoptosis could accelerate the process of cardiovascular diseases. 14‐3‐3‐η protein has been proved to be a potent antiapoptosis molecule. However, inhibition of EPCs apoptosis by 14‐3‐3‐η and further specific mechanism have not been investigated. EPCs were isolated from human cord blood, and identified using VEGFR2 and CD34. 14‐3‐3‐η overexpression model in vitro was established. Cell invasion, apoptosis, and proliferation were measured by transwell, flow cytometry, and Cell Counting Kit‐8, respectively. Expression of 14‐3‐3‐η, Bcl‐2, and voltage‐dependent anion channel 1 (VDAC1) were measured using quantitative real‐time polymerase chain reaction and western blot analysis. Reactive oxygen species (ROS) intensity was measured using 2ʹ‐7ʹ dichlorofluorescin diacetate probe. Mitochondrial membrane potential was detected using JC‐1 dye. Overexpression of 14‐3‐3‐η significantly promoted invasion and proliferation, but suppressed apoptosis of EPCs. Overexpression of 14‐3‐3‐η remarkably inhibited ROS and promoted antioxidant enzyme levels in EPCs. 14‐3‐3‐η might inhibit apoptosis of EPCs through attenuating mitochondrial injury. This study might provide a new target, 14‐3‐3‐η, for the prevention and treatment of cardiovascular diseases through targeting EPCs. [ABSTRACT FROM AUTHOR]

Cell sheet techniques are widely used in bone engineering. However, vascularization remains a challenge in fabricating vascularized engineered bone. The goal of this study was to induce adipose‐derived stem cell (ADSC) osteogenic and angiogenic lineage differentiation and investigate the use of bidiretionally differentiated ADSCs for bone regeneration. ADSCs were cultured to form an osteogenic cell sheet. Other ADSCs were induced to differentiate into endothelial progenitor cells (EPCs), which were identified and characterized by morphological observation and CD31 immunofluorescent staining. Then, the ADSC sheet‐EPC complexes were implanted subcutaneously into nude mice, while ADSC sheets alone were implanted as a control. After 8 weeks of transplantation, microcomputed tomography (micro‐CT) and histological observation were used to assess bone formation. We then implanted the complexes in calvarial defects in rabbits and assessed bone repair by micro‐CT and histological analysis. The ADSC sheets consisted of multiple layers of cells and extracellular matrix. The obtained EPCs formed capillary‐like structures and expressed the specific antigen marker CD31. The osteogenic ADSC sheet‐EPC complexes formed dense and well‐vascularized new bone tissue at 8 weeks after implantation. Bone density was significantly lower in the control group than in the complex group (p <.05). In addition, the reconstruction of calvarial defects in rabbits in complex group was obviously greater than that in the control group (p <.05). These results suggested that the approach of engineering bone tissue with bidiretionally differentiated ADSCs enabled bone regeneration, thus offering a promising strategy for repairing bone defects. [ABSTRACT FROM AUTHOR]

Diabetic vascular complications are closely associated with long‐term vascular dysfunction and poor neovascularization. Endothelial progenitor cells (EPCs) play pivotal roles in maintaining vascular homeostasis and triggering angiogenesis, and EPC dysfunction contributes to defective angiogenesis and resultant diabetic vascular complications. Fibroblast growth factor 21 (FGF21) has received substantial attention as a potential therapeutic agent for diabetes via regulating glucose and lipid metabolism. However, the effects of FGF21 on diabetic vascular complications remain unclear. In the present study, the in vivo results showed that FGF21 efficiently improved blood perfusion and ischaemic angiogenesis in both type 1 and type 2 diabetic mice, and these effects were accompanied by enhanced EPC mobilization and infiltration into ischaemic muscle tissues and increases in plasma stromal cell–derived factor‐1 concentration. The in vitro results revealed that FGF21 directly prevented EPC damage induced by high glucose, and the mechanistic studies demonstrated that nicotinamide adenine dinucleotide (NAD+) was dramatically decreased in EPCs challenged with high glucose, whereas FGF21 treatment significantly increased NAD+ content in an AMPK‐dependent manner, resulting in improved angiogenic capability of EPCs. These results indicate that FGF21 promotes ischaemic angiogenesis and the angiogenic ability of EPCs under diabetic conditions by activating the AMPK/NAD+ pathway. [ABSTRACT FROM AUTHOR]

One of the major reasons for the delayed wound healing in diabetes is the dysfunction of endothelial progenitor cells (EPCs) induced by hyperglycaemia. Improvement of EPC function may be a potential strategy for accelerating wound healing in diabetes. Procyanidin B2 (PCB2) is one of the major components of procyanidins, which exhibits a variety of potent pharmacological activities. However, the effects of PCB2 on EPC function and diabetic wound repair remain elusive. We evaluated the protective effects of PCB2 in EPCs with high glucose (HG) treatment and in a diabetic wound healing model. EPCs derived from human umbilical cord blood were treated with HG. The results showed that PCB2 significantly preserved the angiogenic function, survival and migration abilities of EPCs with HG treatment, and attenuated HG‐induced oxidative stress of EPCs by scavenging excessive reactive oxygen species (ROS). A mechanistic study found the protective role of PCB2 is dependent on activating nuclear factor erythroid 2‐related factor 2 (Nrf2). PCB2 increased the expression of Nrf2 and its downstream antioxidant genes to attenuate the oxidative stress induced by HG in EPCs, which were abolished by knockdown of Nrf2 expression. An in vivo study showed that intraperitoneal administration of PCB2 promoted wound healing and angiogenesis in diabetic mice, which was accompanied by a significant reduction in ROS level and an increase in circulating EPC number. Taken together, our results indicate that PCB2 treatment accelerates wound healing and increases angiogenesis in diabetic mice, which may be mediated by improving the mobilization and function of EPCs. [ABSTRACT FROM AUTHOR]

A major challenge to treat vascular endothelial injury is the restoration of endothelium integrity in which endothelial progenitor cells (EPCs) plays a central role. Transplantation of EPCs as a promising therapeutic means is subject to two interrelated processes, homing and differentiation of EPCs in vivo, and thus a lack of either one may greatly affect the outcome of EPC‐based therapy. Herein, a polymeric nanocarrier is applied for the codelivery of CXCR4 and VEGFa genes to simultaneously promote the migration and differentiation of EPCs. Moreover, MRI T2 contrast agent SPION and NIR dye Cy7.5 are also loaded into the nanocarrier in order to track EPCs in vivo. Based on the synergistic effect of the two codelivered genes, an improved reendothelialization of EPCs is achieved in a rat carotid denuded model. The results show the potential of this bimodal imaging‐visible nanomedicine to improve the performance of EPCs in repairing arterial injury, which may push forward the stem cell‐based therapy of cardiovascular disease. [ABSTRACT FROM AUTHOR]

Intimal injury is an early stage of several cardiovascular diseases. Endothelial progenitor cells (EPCs) play a significant role in endothelial repair following vascular injury. Once the intima is damaged, EPCs are mobilized from the bone marrow to the injury site. Meanwhile, the injury to the intimal surface triggers platelet degranulation, aggregation, and adhesion to the damaged endothelium, and exposed collagen stimulates platelet to secrete platelet‐derived microvesicles (PMVs). However, the role of PMVs in EPC function during this process remains unknown. In an in vivo study, EPCs and platelets were found to adhere to the injury site in Sprague‐Dawley (SD) rat vascular injury model. In vitro, collagen stimulation induced the release of PMVs, and collagen‐activated PMVs (ac.PMVs) significantly promoted EPC proliferation. Transforming growth factor‐β1 (TGF‐β1) content was increased in ac.PMVs. Activated PMVs significantly upregulated Smad3 phosphorylation in EPCs and increased Smad3 nuclear translocation from the cytoplasm. TGF‐β1 knockdown ac.PMVs downregulated EPC proliferation. Recombinant TGF‐β1 enhanced EPC proliferation. The TGF‐β1 inhibitor SB431542 significantly repressed the intracellular signal triggered by ac.PMVs. Furthermore, the Smad3‐specific phosphorylation inhibitor SIS3 effectively reversed the cell proliferation induced by ac.PMVs. Smad3 translocated to the nucleus and enhanced EPC proliferation via its downstream genes tenascin C (TNC), CDKN1A, and CDKN2A. r‐TGF‐β1 promoted reendothelialization and EPC proliferation in vivo. Our data demonstrate that activated PMVs deliver TGF‐β1 from collagen‐activated platelets to EPCs, which in turn activates Smad3 phosphorylation and regulates TNC, CDKN1A, and CDKN2A expression to promote EPC proliferation, suggesting that PMVs act as a key transporter and a potential therapeutic target for vascular injury. [ABSTRACT FROM AUTHOR]

Aims: We previously showed that the protective effects of endothelial progenitor cells (EPCs)‐released exosomes (EPC‐EXs) on endothelium in diabetes. However, whether EPC‐EXs are protective in diabetic ischemic stroke is unknown. Here, we investigated the effects of EPC‐EXs on diabetic stroke mice and tested whether miR‐126 enriched EPC‐EXs (EPC‐EXsmiR126) have enhanced efficacy. Methods: The db/db mice subjected to ischemic stroke were intravenously administrated with EPC‐EXs 2 hours after ischemic stroke. The infarct volume, cerebral microvascular density (MVD), cerebral blood flow (CBF), neurological function, angiogenesis and neurogenesis, and levels of cleaved caspase‐3, miR‐126, and VEGFR2 were measured on day 2 and 14. Results: We found that (a) injected EPC‐EXs merged with brain endothelial cells, neurons, astrocytes, and microglia in the peri‐infarct area; (b) EPC‐EXsmiR126 were more effective than EPC‐EXs in decreasing infarct size and increasing CBF and MVD, and in promoting angiogenesis and neurogenesis as well as neurological functional recovery; (c) These effects were accompanied with downregulated cleaved caspase‐3 on day 2 and vascular endothelial growth factor receptor 2 (VEGFR2) upregulation till day 14. Conclusion: Our results indicate that enrichment of miR126 enhanced the therapeutic efficacy of EPC‐EXs on diabetic ischemic stroke by attenuating acute injury and promoting neurological function recovery. [ABSTRACT FROM AUTHOR]

Objectives: In a previous rat model, MRONJ occurrence was 50%. Our aim was to investigate the potential of endothelial progenitor cells (EPCs) to improve fibroblasts function and prevent MRONJ. Methods: Human gingival fibroblasts were cultured with EPC‐conditioned media (EPC‐CM); endothelial growth media (EGM‐2) or DMEM followed by incubation with 10 µM zoledronic (ZOL) and dexamethasone (DEX). Cell proliferation and migration were assessed by XTT and scratch wound healing assays. In vivo, ten Lewis rats were treated weekly with ZOL and DEX for 11 weeks. After a week, EPCs or EGM‐2 were injected to the gingiva around the molars. At 3 weeks, bilateral molars were extracted. After 8 weeks, wound healing was assessed, and serum VEGF and blood vessels were quantified. Results: ZOL/DEX significantly reduced fibroblasts proliferation and wound healing. Treatment with EPC‐CM before ZOL/DEX improved cell proliferation, and scratch healing (p =.007, p =.023). In vivo, local EPC injection before tooth extraction increased serum VEGF (p =.01) and soft tissue vascularization (p =.05). Normal healing was similar (80%) in EPCs and EGM‐2 groups. Conclusion: EPC rescued fibroblasts from the cytotoxic effect of ZOL/DEX and elevated serum VEGF and vessel density that might reduce MRONJ occurrence to 20% compared to 50% in a similar model. [ABSTRACT FROM AUTHOR]

Low‐energy shock wave (LESW) has been recognized as a promising non‐invasive intervention to prevent the organs or tissues against ischaemia reperfusion injury (IRI), whereas its effect on kidney injury is rarely explored. To investigate the protective role of pretreatment with LESW on renal IRI in rats, animals were randomly divided into Sham, LESW, IRI and LESW + IRI groups. At 4, 12, 24 hours and 3 and 7 days after reperfusion, serum samples and renal tissues were harvested for performing the analysis of renal function, histopathology, immunohistochemistry, flow cytometry and Western blot, as well as enzyme‐linked immunosorbent assay. Moreover, circulating endothelial progenitor cells (EPCs) were isolated, labelled with fluorescent dye and injected by tail vein. The fluorescent signals of EPCs were detected using fluorescence microscope and in vivo imaging system to track the distribution of injected circulating EPCs. Results showed that pretreatment with LESW could significantly reduce kidney injury biomarkers, tubular damage, and cell apoptosis, and promote cell proliferation and vascularization in IRI kidneys. The renoprotective role of LESW pretreatment would be attributed to the remarkably increased EPCs in the treated kidneys, part of which were recruited from circulation through SDF‐1/CXCR7 pathway. In conclusion, pretreatment with LESW could increase the recruitment of circulating EPCs to attenuate and repair renal IRI. [ABSTRACT FROM AUTHOR]

In neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis and amyotrophic lateral sclerosis, neuroinflammation can lead to blood‐brain barrier (BBB) breakdown. After intravenous or intra‐arterial injection into mice, endothelial progenitor cells (EPCs) home to the damaged BBB to promote neurovascular repair. Autologous EPCs transfected to express specific therapeutic proteins offer an innovative therapeutic option. Here, we demonstrate that EPC transfection by electroporation with plasmids encoding the reporter protein GFP or an anti‐β‐amyloid antibody fragment (Fab) leads to secretion of each protein. We also demonstrate the secreted anti‐β‐amyloid Fab protein functions in β‐amyloid aggregate solubilization. [ABSTRACT FROM AUTHOR]

Synthetic grafts do not provide an appealing surface for endothelial cells to adhere and colonize the inner surface. To promote in situ endothelialization the following aspect has to be taken into account, endothelial progenitor cells (EPCs) needs to be mobilized on the surface of the graft. The surface of the graft has to be sufficiently biocompatible to create a prone environment for the EPCs to adhere, proliferate and, differentiate to form a layer and subsequently improve graft patency. In this work, two active molecules GRGDS and sitagliptin, were chosen for their abilities to recruit, enhance adhesion and induce differentiation of endothelial progenitor cells. They were grafted on PET surfaces in order to provide restrained cues triggering cell alignment and evaluate the influence of such structuration on EPCs fate. We then analyze cell behavior onto functionalized biomaterials. Their abilities to control EPCs fate were demonstrated via RT‐qPCR, immunofluorescence, and enzymatic tests. The GRGDS/sitagliptin 100 × 10 surface enables to reduce the stemness phenotype on EPCs and induce the expression of endothelial lineage markers. These results highlight the importance of spatial patterning cues in guiding EPCs organization and function, which may have clinical relevance in the development of vascular grafts that promote patency. [ABSTRACT FROM AUTHOR]

Endothelial progenitor cells (EPCs) are able to trigger angiogenesis, and pro‐inflammatory cytokines have beneficial effects on angiogenesis under physiological and pathological conditions. C‐X‐C chemokine receptor type 7 (CXCR‐7), receptor for stromal cell‐derived factor‐1, plays a critical role in enhancing EPC angiogenic function. Here, we examined whether CXCR7 mediates the pro‐angiogenic effects of the inflammatory cytokine interleukin‐1β (IL‐1β) in EPCs. EPCs were isolated by density gradient centrifugation and angiogenic capability was evaluated in vitro by Matrigel capillary formation assay and fibrin gel bead assay. IL‐1β elevated CXCR7 expression at both the transcriptional and translational levels in a dose‐ and time‐dependent manner, and blockade of the nuclear translocation of NF‐κB dramatically attenuated the IL‐1β‐mediated up‐regulation of CXCR7 expression. IL‐1β stimulation significantly promoted EPCs tube formation and this effect was largely impaired by CXCR7‐siRNA transfection. IL‐1β treatment stimulated extracellular signal‐regulated kinase 1/2 (Erk1/2) phosphorylation, and inhibition of Erk1/2 phosphorylation partially impaired IL‐1β‐induced tube formation of EPCs but without significant effects on CXCR7 expression. Moreover, blocking NF‐κB had no significant effects on IL‐1β‐stimulated Erk1/2 phosphorylation. These findings indicate that CXCR7 plays an important role in the IL‐1β‐enhanced angiogenic capability of EPCs and antagonizing CXCR7 is a potential strategy for inhibiting angiogenesis under inflammatory conditions. [ABSTRACT FROM AUTHOR]

Endothelial progenitor cells (EPCs) have emerged as a promising therapeutic choice for thrombi recanalization. However, this role of EPCs is confined by some detrimental factors. The aim of this study was to explore the role of the miR‐9‐5p in regulation of the proliferation, migration and angiogenesis of EPCs and the subsequent therapeutic role in thrombosis event. Wound healing, transwell assay, tube formation assay and in vivo angiogenesis assay were carried out to measure cell migration, invasion and angiogenic abilities, respectively. Western blot was performed to elucidate the relationship between miR‐9‐5p and TRPM7 in the autophagy pathway. It was found that miR‐9‐5p could promote migration, invasion and angiogenesis of EPCs by attenuating TRPM7 expression via activating PI3K/Akt/autophagy pathway. In conclusion, miR‐9‐5p, targets TRPM7 via the PI3K/Ak/autophagy pathway, thereby mediating cell proliferation, migration and angiogenesis in EPCs. Acting as a potential therapeutic target, miR‐9‐5p may play an important role in the prognosis of DVT. [ABSTRACT FROM AUTHOR]

Apatitic bone cements have been used as a clinical bone substitutes and drug delivery vehicles for therapeutic agents in orthopedic applications. This has led to their combination with different drugs with known ability to foster bone formation. Recent studies have evaluated Simvastatin for its role in enhanced bone regeneration, but its lipophilicity hampers incorporation and release to and from the bone graft. In this study, injectable calcium phosphate foams (i‐CPF) based on α‐tricalcium phosphate were loaded for the first time with Pitavastatin. The stability of the drug in different conditions relevant to this study, the effect of the drug on the i‐CPFs properties, the release profile, and the in vitro biological performance with regard to mineralization and vascularization were investigated. Pitavastatin did not cause any changes in neither the micro nor the macro structure of the i‐CPFs, which retained their biomimetic features. PITA‐loaded i‐CPFs showed a dose‐dependent drug release, with early stage release kinetics clearly affected by the evolving microstructure due to the setting of cement. in vitro studies showed dose‐dependent enhancement of mineralization and vascularization. Our findings contribute towards the design of controlled release with low drug dosing bone grafts: i‐CPFs loaded with PITA as osteogenic and angiogenic agent. [ABSTRACT FROM AUTHOR]

Endothelial progenitor cells (EPCs) promote neovascularization and tissue repair by migrating to vascular injury sites; therefore, factors that enhance EPC homing to damaged tissues are of interest. Here, we provide evidence of the prominent role of the Netrin‐4 (NTN4)–Unc‐5 Netrin receptor B (UNC5B) axis in EPC‐specific promotion of ischemic neovascularization. Our results showed that NTN4 promoted the proliferation, chemotactic migration, and paracrine effects of small EPCs (SEPCs) and significantly increased the incorporation of large EPCs (LEPCs) into tubule networks. Additionally, NTN4 prominently augmented neovascularization in mice with hindlimb ischemia by increasing the homing of exogenously transplanted EPCs to the ischemic limb and incorporating EPCs into vessels. Moreover, silencing of UNC5B, an NTN4 receptor, abrogated the NTN4‐induced cellular activities of SEPCs in vitro and blood‐flow recovery and neovascularization in vivo in ischemic muscle by reducing EPC homing and incorporation. These findings suggest NTN4 as an EPC‐based therapy for treating angiogenesis‐dependent diseases. [ABSTRACT FROM AUTHOR]

Background: Endothelial progenitor cells (EPCs) help in neovascularization and endothelial repair during injury. Patients with cirrhosis show increased number and function of EPCs in circulation. Methods: Since natural killer (NK) cells regulate EPCs, we investigated the relationship between the 2 in alcoholic cirrhosis (AC, n = 50) and severe alcoholic hepatitis (SAH, n = 18) patients and compared with nonalcoholic cirrhosis (n = 15) and healthy controls (HC, n = 30). Levels of systemic inflammatory cytokines were measured, and coculture assays were performed between EPCs and NK cells in contact‐dependent and contact‐independent manner. NK cell–mediated killing of EPCs was evaluated, and expression of receptors including fractalkine (FKN) on EPCs and its cognate receptor CX3CR1 on NK cells was studied by RT‐PCR assays. Results: Patients with SAH had higher regulated on activation, normal T cell expressed and secreted (RANTES) (p = 0.01), vascular endothelial growth factor (VEGF) (p = 0.04), IL‐1β (p = 0.04), and IL‐6 (p = 0.00) growth factors and proinflammatory cytokines as compared to AC and HC. Distinct populations of CD31+ CD34+ EPCs with low and high expression of CD45 were significantly lower in SAH than HC (CD45low, p = 0.03; CD45hi, p = 0.04) and AC (CD45low, p = 0.05; CD45hi, p = 0.02). SAH patients, however, showed increased functional capacity of EPCs including colony formation and LDL uptake. NK cells were reduced in SAH compared with AC (p = 0.002), however with higher granzyme ability (p < 0.001 and p = 0.04, respectively). In SAH, EPC‐NK cell interaction assays showed that NK cells lysed the EPCs in both contact‐dependent and contact‐independent assays. Expression of interaction receptor CX3CR1 was significantly higher on NK cells (p = 0.0005), while its cognate receptor, FKN, was increased on EPCs in SAH patients as compared to HC (p = 0.0055). Conclusion: We conclude that in SAH, NK cells induce killing of EPCs via CX3CR1/FKN axis that may be one of the key events contributing to disease severity and proinflammatory responses in SAH. [ABSTRACT FROM AUTHOR]

The objective of the current study is to investigate the effect of PTGS2 on proliferation, migration, angiogenesis and apoptosis of endothelial progenitor cells (EPCs) in mice with ischemic stroke through the NF‐κB signaling pathway. Middle cerebral artery occlusion (MCAO) model was established in mice. EPCs were identified, in which ectopic expression and depletion experiments were conducted. The mRNA and protein expression of related factors in tissues and cells were measured. Besides, proliferation, migration, angiogenesis, and apoptosis, as well as cell cycle distribution, of cells were determined. MCAO mice showed overexpression of interleukin‐6 (IL‐6), IL‐17, and IL‐23, and increased positive protein expression of PTGS2, as well as expression of PTGS2, nuclear factor‐κB (NF‐κB), tumor suppressor region 1 (TSP‐1) and Bcl‐2‐associated X protein (Bax), but underexpression of vascular endothelial growth factor (VEGF), S‐phase kinase associated protein 2 (Skp2), and B‐cell lymphoma 2 (Bcl‐2). Moreover, ectopic expression of tumor necrosis factor‐α significantly elevated the expression of PTGS2, NF‐κB, TSP‐1, and Bax, as well as cell apoptosis and cell cycle arrest, but decreased the expression of VEGF, Skp2, and Bcl‐2, as well as proliferation, migration and angiogenesis of EPCs, and the PTGS2‐siRNA group showed an opposite trend. Taken together, we conclude that the specific knockdown of PTGS2 expression could repress the NF‐κB signaling pathway, thereby inhibits apoptosis and promotes proliferation, migration and angiogenesis of EPCs, providing protective effect on mice with ischemic stroke. [ABSTRACT FROM AUTHOR]

Background: This study investigated whether gCTRP9 (globular C1q/tumor necrosis factor-related protein-9) could restore high-glucose (HG)-suppressed endothelial progenitor cell (EPC) functions by activating the endothelial nitric oxide synthase (eNOS)., Methods and Results: EPCs were treated with HG (25 mmol/L) and gCTRP9. Migration, adhesion, and tube formation assays were performed. Adiponectin receptor 1, adiponectin receptor 2, and N-cadherin expression and AMP-activated protein kinase, protein kinase B, and eNOS phosphorylation were measured by Western blotting. eNOS activity was determined using nitrite production measurement. In vivo reendothelialization and EPC homing assays were performed using Evans blue and immunofluorescence in mice. Treatment with gCTRP9 at physiological levels enhanced migration, adhesion, and tube formation of EPCs. gCTRP9 upregulated the phosphorylation of AMP-activated protein kinase, protein kinase B, and eNOS and increased nitrite production in a concentration-dependent manner. Exposure of EPCs to HG-attenuated EPC functions induced cellular senescence and decreased eNOS activity and nitric oxide synthesis; the effects of HG were reversed by gCTRP9. Protein kinase B knockdown inhibited eNOS phosphorylation but did not affect gCTRP9-induced AMP-activated protein kinase phosphorylation. HG impaired N-cadherin expression, but treatment with gCTRP9 restored N-cadherin expression after HG stimulation. gCTRP9 restored HG-impaired EPC functions through both adiponectin receptor 1 and N-cadherin-mediated AMP-activated protein kinase /protein kinase B/eNOS signaling. Nude mice that received EPCs treated with gCTRP9 under HG medium showed a significant enhancement of the reendothelialization capacity compared with those with EPCs incubated under HG conditions., Conclusions: CTRP9 promotes EPC migration, adhesion, and tube formation and restores these functions under HG conditions through eNOS-mediated signaling mechanisms. Therefore, CTRP9 modulation could eventually be used for vascular healing after injury.

Pulmonary hypertension (PH) is an incurable disease characterized by pulmonary vascular remodeling and ultimately death. Two rodent models of PH include treatment with monocrotaline or exposure to a vascular endothelial growth factor receptor inhibitor and hypoxia. Studies in these models indicated that damaged lung cells evolve extracellular vesicles which induce production of progenitors that travel back to the lung and induce PH. A study in patients with pulmonary myelofibrosis and PH indicated that 100 cGy lung irradiation could remit both diseases. Previous studies indicated that murine progenitors were radiosensitive at very low doses, suggesting that 100 cGy treatment of mice with induced PH might be an effective PH therapy. Our hypothesis is that the elimination of the PH‐inducing marrow cells by low dose irradiation would remove the cellular influences creating PH. Here we show that low dose whole‐body irradiation can both prevent and reverse established PH in both rodent models of PH. [ABSTRACT FROM AUTHOR]

With the changing lifestyle, venous thrombosis (VT) is becoming increasingly prevalent and poses a burden on the health economy. Endothelial progenitor cells (EPCs) are recruited into resolving VT. We aimed to investigate the effect of plasminogen activator inhibitor 1 (PAI‐1) silencing on the recanalization of VT in rat EPCs. EPCs and VT rat models were cultured and treated with negative control‐siRNA vector and PAI‐1‐siRNA vector, respectively. 4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay, wound‐healing test, and Matrigel‐induced tubular experiment were performed to detect the ability of cell proliferation, migration, and EPCs lumen formation. Immunohistochemistry was used to observe the recanalization of thrombus. The messenger RNA (mRNA) and protein expression of PAI‐1 and vascular endothelial growth factor (VEGF) were determined by reverse transcription quantitative polymerase chain reaction and Western blot analysis. PAI‐1‐siRNA enhances the luminal formation ability of EPCs and significantly promotes EPCs homing. In response to PAI‐1 gene silencing, tissues from inferior vena cava displayed reduced mRNA and protein expression of PAI‐1, increased VEGF expression as well as promoted lumen‐like structures. PAI‐1 gene silencing can promote the recanalization of VT by enhancement of the luminal formation ability of rats' EPCs. [ABSTRACT FROM AUTHOR]

The expansion of human peripheral blood endothelial progenitor cells to obtain therapeutically relevant endothelial colony‐forming cells (ECFCs) has been commonly performed on xeno‐derived extracellular matrix proteins. For cellular therapy applications, xeno‐free culture conditions are desirable to improve product safety and reduce process variability. We have previously described a novel fluorophore‐tagged RGD peptide (RGD‐TAMRA) that enhanced the adhesion of mature endothelial cells in vitro. To investigate whether this peptide can replace animal‐derived extracellular matrix proteins in the isolation and expansion of ECFCs, peripheral blood mononuclear cells from 22 healthy adult donors were seeded on RGD‐TAMRA‐modified polystyrene culture surfaces. Endothelial colony formation was significantly enhanced on RGD‐TAMRA‐modified surfaces compared to the unmodified control. No phenotypic differences were detected between ECFCs obtained on RGD‐TAMRA compared to ECFCs obtained on rat‐tail collagen‐coated surfaces. Compared with collagen‐coated surfaces and unmodified surfaces, RGD‐TAMRA surfaces promoted ECFC adhesion, cell spreading, and clonal expansion. This study presents a platform that allows for a comprehensive in vitro evaluation of peptide‐based biofunctionalization as a promising avenue for ex vivo ECFC expansion. [ABSTRACT FROM AUTHOR]

Angiogenesis is a critical parameter to consider for the development of tissue‐engineered bone substitutes. The challenge is to promote sufficient vascularization in the bone substitute to prevent cell death and to allow its efficient integration. The capacity of nacre extract to restore the osteogenic activity of osteoarthritis osteoblasts has already been demonstrated. However, their angiogenic potential on endothelial progenitor cells (EPCs) was not yet explored. Therefore, the current study aimed at investigating if nacreous molecules affect EPC behavior. The gene and protein expression levels of endothelial cell (EC)‐specific markers were determined in EPCs cultivated in presence of a nacre extract (ethanol soluble matrix [ESM] at two concentrations: 100 μg/mL and 200 μg/mL (respectively abbreviated ESM100 and ESM200)). Cell functionality was explored by proangiogenic factors production and in vitro tube formation assay. ESM200 increased the expression of some EC‐specific genes. The in vitro tube formation assay demonstrated that ESM200 stimulated tubulogenesis affecting angiogenic parameters. We demonstrated that a stimulation with 200 μg/mL of ESM increased angiogenesis key elements. This in vitro study strongly highlights the proangiogenic effect of ESM. Due to its osteogenic properties, previously demonstrated, ESM could constitute the key element to develop an ideal prevascularized bone substitute. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2019. [ABSTRACT FROM AUTHOR]

Bone repair involves bone resorption through osteoclastogenesis and the stimulation of neovascularization and osteogenesis by endothelial progenitor cells (EPCs). However, the role of EPCs in osteoclastogenesis is unclear. In this study, we assess the effects of EPC‐derived exosomes on the migration and osteoclastic differentiation of primary mouse bone marrow‐derived macrophages (BMMs) in vitro using immunofluorescence, western blotting, RT‐PCR and Transwell assays. We also evaluated the effects of EPC‐derived exosomes on the homing and osteoclastic differentiation of transplanted BMMs in a mouse bone fracture model in vivo. We found that EPCs cultured with BMMs secreted exosomes into the medium and, compared with EPCs, exosomes had a higher expression level of LncRNA‐MALAT1. We confirmed that LncRNA‐MALAT1 directly binds to miR‐124 to negatively control miR‐124 activity. Moreover, overexpression of miR‐124 could reverse the migration and osteoclastic differentiation of BMMs induced by EPC‐derived exosomes. A dual‐luciferase reporter assay indicated that the integrin ITGB1 is the target of miR‐124. Mice treated with EPC‐derived exosome‐BMM co‐transplantations exhibited increased neovascularization at the fracture site and enhanced fracture healing compared with those treated with BMMs alone. Overall, our results suggest that EPC‐derived exosomes can promote bone repair by enhancing recruitment and differentiation of osteoclast precursors through LncRNA‐MALAT1. [ABSTRACT FROM AUTHOR]

Summary: Endothelial progenitor cells (EPCs) are critical for vascular regeneration and function, but are reduced in hypertensive disorders of pregnancy. We aimed to determine the possible effects of antihypertensive drugs, such as metoprolol, methyldopa, and nifedipine, on EPC number and functions in patients with gestational hypertension and preeclampsia. We collected blood samples from 30 normal pregnant women, 67 patients with gestational hypertension and 48 patients with preeclampsia. The patients received no drug or an antihypertensive drug, such as metoprolol, methyldopa, or nifedipine, between 20 and 24 weeks of gestation. The number of EPCs and circulating endothelial cells (CECs) in the blood was measured by flow cytometry. Moreover, colony formation and migration assays were performed on the isolated EPCs. Both the systolic and diastolic blood pressure (BP) increased, while the percentage of flow‐mediated vasodilatation (FMD) decreased in patients with gestational hypertension and preeclampsia, compared to the healthy controls at 20 weeks of gestation. CEC number increased in the patients, whereas EPC counts decreased. Furthermore, EPC colony formation and migration abilities were also impaired in the patients. However, administration of metoprolol, methyldopa, or nifedipine effectively restored the systolic and diastolic BP, FMD%, EPCs, and CEC numbers, as well as EPC migration capacity. Endothelial progenitor cells colony formation ability selectively improved with methyldopa and nifedipine. In patients receiving no drugs, most of these indexes worsened within 4 weeks (study duration). This study revealed a new pharmacological action of these antihypertensive drugs against gestational hypertension and preeclampsia, thus supporting their clinical use. [ABSTRACT FROM AUTHOR]

Background: Patients with a history of Hodgkin's lymphoma (HL) are at increased long‐term risk of cardiovascular morbidity and mortality. Studies report an association between the pathophysiology of coronary artery disease (CAD) and levels of circulating endothelial progenitor cells (EPC), which play an essential role in vascular injury repair. The aim of the present study was to investigate the potential involvement of abnormal EPC level or function in the CAD risk of survivors of HL in remission. Methods: EPCs were isolated from peripheral blood samples drawn from 4 groups of patients aged 20‐50 years with no history of CAD: 17 patients with HL who had been in complete remission for at least 2 years, four newly diagnosed patients with HL before treatment, 28 patients with diabetes all attending a tertiary medical center, and 16 healthy individuals. Levels of EPC surface markers were measured by flow cytometry, and EPC function was evaluated by the number of colony‐forming units (CFUs) and MTT assay. Results: Levels of circulating CD34(+)/VEGFR2(+) and CD133(+)/VEGFR2(+) were significantly higher in the newly diagnosed untreated patients with HL compared to the patients with HL in remission (P = 0.03 and P = 0.005, respectively), in the patients in remission compared to the patients with diabetes (P = 0.011 and P < 0.001, respectively), and in the patients in remission compared to the healthy individuals (P = 0.08 and P = 0.003, respectively). The analysis of cell viability and the number of colony‐forming units in the patients with HL in remission yielded significant differences from the healthy group (P = 0.005 and P < 0.001, respectively) but not from either the newly diagnosed patients with HL or the diabetic patients. Conclusions: These results suggest that patients in complete remission of HL for at least 2 years have an abnormal EPC profile characterized by high circulating levels but attenuated function. This study focused on the level and function of circulating endothelial progenitor cells (EPC) in patients with Hodgkin's lymphoma aged 20‐50 years, without a history of CAD, who were in complete remission for at least two years following a standard anti‐Hodgkin lymphoma regimen. The patients in remission from Hodgkin's lymphoma had a unique EPC profile characterized by increased circulating levels, similar to patients with newly diagnosed untreated Hodgkin's lymphoma, but a significant attenuation of function, as seen in diabetic patients. [ABSTRACT FROM AUTHOR]

Although the critical role of hypoxia inducible factor‐1α (HIF‐1α) in cerebral neovascularization after stroke has been well characterized, the details regarding the regulation of endothelial progenitor cell (EPC)‐dependent neovascularization by HIF‐1α are not completely understood. Using lentiviral shRNA to knockdown HIF‐1α, we showed that HIF‐1α plays a central role in bone marrow‐derived EPC (bmEPC) homing and sprouting in the post‐acute stage of ischemic Sprague Dawley (SD) rat brains. First, knockdown of HIF‐1α decreased the homing of both endogenous and exogenous bmEPCs to the ischemic brain. Additionally, the knockdown impaired the incorporation and sprouting of bmEPCs in the ischemic brain. In vitro, knockdown of HIF‐1α inhibited the spheroid sprouting and tube formation of bmEPCs. Mechanically, the HIF‐1α‐dependent recruitment of bmEPCs to the ischemic brain was relative to the CXCL12/CXCR4 axis and HMGB1, which were relative to astrocytes. In addition, the loss of HIF‐1α resulted in deficient expression levels of VEGF‐A, Flk‐1, NRP1, and Dll4 in the ischemic brains, bmEPCs, and astrocytes. These findings suggested that HIF‐1α implicates in bmEPC homing via CXCL12/CXCR4 and HMGB1 and that it promotes bmEPC sprouting via VEGF‐A/flk1‐NRP1/Dll4. [ABSTRACT FROM AUTHOR]

Abstract: The possibility to employ stem/progenitor cells in the cardiovascular remodelling after myocardial infarction is one of the main queries of regenerative medicine. To investigate whether endothelial progenitor cells (EPCs) participate in the restoration of hypoxia‐affected myocardium, we used a co‐culture model that allowed the intimate interaction between EPCs and myocardial slices, mimicking stem cell transplantation into the ischaemic heart. On this model, we showed that EPCs engrafted to some extent and only transiently survived into the host tissue, yet produced visible protective effects, in terms of angiogenesis and protection against apoptosis and identified miR‐377‐VE‐PTP axis as being involved in the protective effects of EPCs in hypoxic myocardium. We also showed that collagen, the main component of the myocardial scar, was important for these protective effects by preserving VE‐PTP levels, which were otherwise diminished by miR‐377. By this, a good face of the scar is revealed, which was so far perceived as having only detrimental impact on the exogenously delivered stem/progenitor cells by affecting not only the engraftment, but also the general protective effects of stem cells. [ABSTRACT FROM AUTHOR]

Summary: Graft‐versus‐host disease (GVHD) is a major complication after allogeneic haematopoietic stem cell transplantation (allo‐HSCT) that is frequently associated with bone marrow (BM) suppression, and clinical management is challenging. BM endothelial progenitor cells (EPCs) play crucial roles in the regulation of haematopoiesis and thrombopoiesis. However, little is known regarding the functional roles of BM EPCs in acute GVHD (aGVHD) patients. In the current prospective case‐control study, reduced and dysfunctional BM EPCs, characterized by decreased migration and angiogenesis capacities and increased levels of reactive oxygen species (ROS) and apoptosis, were found in aGVHD patients compared with those without aGVHD. Moreover, lower frequency and increased levels of ROS, apoptosis and DNA damage, but reduced colony‐forming unit‐plating efficiency were found in BM CD34+ cells of aGVHD patients compared with those without aGVHD. The severity of aGVHD and GVHD‐mediated cytopenia was associated with BM EPC impairment in aGVHD patients. In addition, the EPC impairment positively correlated with ROS level. Taken together, our results suggest that reduced and dysfunctional BM EPCs may be involved in the pathogenesis of aGVHD. Although these findings require validation, our data indicate that improvement of BM EPCs may represent a promising therapeutic approach for aGVHD patients. [ABSTRACT FROM AUTHOR]

Abstract: We tested the hypothesis that daily melatonin treatment protects endothelial lineage and functional integrity against the aging process, oxidative stress/endothelial denudation (ED), and toxic environment and restored blood flow in murine critical limb ischemia (CLI). In vitro study using HUVECs, in vivo models (ie, CLI through left femoral artery ligation and ED through carotid artery wire injury), and model of lipopolysaccharide‐induced aortic injury in young (3 months old) and aged (8 months old) mice were used to elucidate effects of melatonin treatment on vascular endothelial integrity. In vitro study showed that menadione‐induced oxidative stress (NOX‐1/NOX‐2), inflammation (TNF‐α/NF‐kB), apoptosis (cleaved caspase‐3/PARP), and mitochondrial damage (cytosolic cytochrome c) in HUVECs were suppressed by melatonin but reversed by SIRT3‐siRNA (all P < .001). In vivo, reduced numbers of circulating endothelial progenitor cells (EPCs) (C‐kit/CD31+/Sca‐1/KDR+/CXCR4/CD34+), and angiogenesis (Matrigel assay of bone marrow‐derived EPC and ex vivo aortic ring cultures) in older (compared with younger) mice were significantly reversed through daily melatonin administration (20 mg/kg/d, ip) (all P < .001). Aortic vasorelaxation and nitric oxide release were impaired in older mice and reversed in age‐match mice receiving melatonin (all P < .01). ED‐induced intimal/medial hyperplasia, reduced blood flow to ischemic limb, and angiogenesis (reduced CD31+/vWF+ cells/small vessel number) were improved after daily melatonin treatment (all P < .0001). Lipopolysaccharide‐induced aortic endothelial cell detachment, which was more severe in aged mice, was also alleviated after daily melatonin treatment (P < .0001). Daily melatonin treatment protected both structural and functional integrity of vascular endothelium against aging‐, oxidative stress‐, lipopolysaccharide‐, and ischemia‐induced damage probably through upregulating the SIRT signaling pathway. [ABSTRACT FROM AUTHOR]