Expression In Endothelial Progenitor Cells Research Articles

Linc-ROR Modulates the Endothelial-Mesenchymal Transition of Endothelial Progenitor Cells through the miR-145/Smad3 Signaling Pathway

The endothelial-mesenchymal transition (EndMT) of endothelial progenitor cells (EPCs) plays a notable role in pathological vascular remodeling. Emerging evidence indicated that long non-coding RNA-regulator of reprogramming (linc-ROR) can promote epithelial-mesenchymal transition (EMT) in a variety of cancer cells. Nevertheless, the function of linc-ROR in EPC EndMT has not been well elucidated. The present study investigated the effect and possible mechanisms of function of linc-ROR on the EndMT of EPCs. A linc-ROR overexpression lentiviral vector (LV linc-ROR) or a linc-ROR short hairpin RNA lentiviral vector (LV-shlinc-ROR) was used to up or downregulate linc-ROR expression in EPCs isolated from human umbilical cord blood. Functional experiments demonstrated that LV-linc-ROR promoted the proliferation and migration of EPCs, but inhibited EPC angiogenesis in vitro. In the meantime, reverse transcription-quantitative PCR and western blotting results showed that the expression of the endothelial cell markers vascular endothelial-cadherin and CD31 was decreased, while the expression of the mesenchymal cell markers α-smooth muscle actin and SM22α was increased at both mRNA and protein levels in LV-linc-ROR-treated EPCs, indicating that linc-ROR induced EPC EndMT. Mechanistically, the dual-luciferase reporter assay demonstrated that microRNA (miR/miRNA)-145 was a direct target of linc-ROR, and miR-145 binds to the 3’-untranslated region of Smad3. Moreover, LV-shlinc-ROR increased the expression of miR-145, but decreased the expression of Smad3. In conclusion, linc-ROR promotes EPC EndMT, which may be associated with the miR-145/Smad3 signaling pathway.

The Expression of Circ-Astn1 Inhibits High Glucose Induced Endothelial Progenitor Cell Dysfunction by Activating Autophagy

ABSTRACT Background Diabetes mellitus (DM) and complications such as chronic kidney disease and cardiovascular symptoms pose a substantial public health burden. Increasing studies have shown that circular RNAs (circRNAs) regulate many gene expressions that are essential in diverse pathological and biological procedures. However, the roles of particular circRNAs in DM are unclear. Methods In the current investigation, endothelial progenitor cells (EPCs) were used to search for abnormal expression of circRNAs by using high-throughput sequencing under high glucose (HG) conditions. The regulatory mechanisms and targets were then studied through bioinformatics analysis, luciferase reporter analysis, angiogenic differentiation experiments, flow cytometry detection of apoptosis and RT-qPCR analysis. Results The circ-Astn1 expression in EPCs decreased after HG treatment. Overexpression or circ-Astn1 suppressed HG induced endothelial cell damage. MicroRNA (miR)-138-5p and SIRT5 were found to be the downstream targets of circ-Astn1 through luciferase reporter analysis. SIRT5 downregulation or miR-138-5p overexpression reversed circ-Astn1’s protective effect against HG induced endothelial cell dysfunction, including apoptosis and abnormal vascular differentiation. Furthermore, circ-Astn1 overexpression promoted autophagy activation by increasing SIRT5 expression under HG conditions. Our findings suggest that circ-Astn1 mediated promotion of SIRT5 facilitates autophagy by sponging miR-138-5p. Conlusion Together, our findings show that the overexpression of circ-Astn1 suppresses HG induced endothelial cell damage by targeting miR-138-5p/SIRT5 axis.

DLK1 promoted ischemic angiogenesis through notch1 signaling in endothelial progenitor cells.

Delta like non-canonical Notch ligand 1 (DLK1), as a member of epidermal growth factor-like family, plays a critical role in somatic growth, tissue development and possibly tissue renewal. Though previous studies had indicated that DLK1 contributed to adipogenesis and myogenesis, it's still controversial whether DLK1 affects angiogenesis and how it interacts with Notch signaling with numerous conflicting reports from different models. Based on our preliminary finding that DLK1 expression was up-regulated in mice ischemic gastrocnemius and in the border zone of infarcted myocardium, we administered either recombinant DLK1 (rDLK1) or PBS in C57BL/6 mice after establishment of hindlimb ischemia (HLI) and myocardial infarction (MI), respectively. Exogenous rDLK1 administration significantly improved both blood perfusion of mice ischemic hindlimbs and muscle motor function on the 3rd, 7th day after HLI, by promoting neovascularization. Similar effect on neovascularization was verified in mice on the 28th day after MI as well as improvement of cardiac failure. Correspondingly, the number of CD34+KDR+ cells, indicated as endothelial progenitor cells (EPCs), was significantly in mice ischemic gastrocnemius by rDLK1 administration, which was abrogated by DAPT as the specific inhibitor of Notch intracellular domain (NICD). Furthermore, bone marrow mononuclear cells were obtained from C57BL/6 mice and differentiated to EPCs ex vivo. Incubation with rDLK1 triggered Notch1 mRNA and NICD protein expressions in EPCs as exposed to hypoxia and serum deprivation, promoting EPCs proliferation, migration, anti-apoptosis and tube formation. Otherwise, rDLK1 incubation significantly decreased intracellular and mitochondrial reactive oxygen species, increased ATP content andmitochondrial membrane potential, downregulated short isoform of OPA-1 expression whereas upregulated mitofusin (-1, -2) expression in EPCs by Notch1 signaling, which were all abrogated by DAPT. In summary, the present study unveils the pro-angiogenesis and its mechanism of rDLK1 through activation of Notch1 signaling in endothelial progenitor cells.

Role of Bushen Huoxue Formula and transplanted endothelial progenitor cells play in promoting endplate microcirculation and attenuating intervertebral disc degeneration

ObjectiveTo explore whether Bushen Huoxue Formula (BSHXF) improves the angiogenesis ability of transplanted endothelial progenitor cells (EPCs) in endplate and its potential mechanism in delaying intervertebral disc degeneration (IDD). MethodsBSHXF was analyzed via Ultra-High Performance Liquid Chromatography (UPLC). Rabbit axial compression lumbar IDD models were constructed and the effects of BSHXF, EPCs, and their combination in IDD were determined by MRI, histological evaluation, TUNEL, and immunofluorescence assays. Additionally, CCK-8 assay, flow cytometry, and tube formation assay were used to evaluate EPCs viability, proliferation, cell cycle and the angiogenesis ability of EPCs between groups. ResultsBSHXF and transplanted EPCs both attenuate the process of IDD in the rabbit model assessed by MRI, HE staining and Masson staining. TUNEL-positive NP cells were significantly reduced in the BSHXF group, EPCs group, and EPC + BSHXF group compared to the model group (P < 0.05), with the EPC + BSHXF group showing the most significant therapeutic effect. Immunofluorescence detection showed that VEGF, CD34 expression and quantity of microvessels in the endplate significantly increased in the EPC + BSHXF group compared to all the other groups (P < 0.05). Besides, the CCK-8 assay showed an upregulation of EPC viability and the tube formation assay demonstrated a significant increase in tube length and branching in EPCs cultured with BSHXF-containing serum (P < 0.05). Furthermore, BSHXF-containing serum increased VEGF expression in EPCs cultured in vitro (P < 0.05). ConclusionsBoth BSHXF and EPCs transplantation play an important role in increasing endplate angiogenesis and attenuating IDD. BSHXF can enhance the viability and tube-forming ability of EPCs and endplate microcirculation.

GroEL of Porphyromonas gingivalis-induced microRNAs accelerate tumor neovascularization by downregulating thrombomodulin expression in endothelial progenitor cells.

We found that GroEL in Porphyromonas gingivalis accelerated tumor growth and increased mortality in tumor-bearing mice; GroEL promoted proangiogenic function, which may be the reason for promoting tumor growth. To understand the regulatory mechanisms by which GroEL increases the proangiogenic function of endothelial progenitor cells (EPCs), we explored in this study. In EPCs, MTT assay, wound-healing assay, and tube formation assay were performed to analyze its activity. Western blot and immunoprecipitation were used to study the protein expression along with next-generation sequencing for miRNA expression. Finally, a murine tumorigenesis animal model was used to confirm the results of in vitro. The results indicated that thrombomodulin (TM) direct interacts with PI3 K/Akt to inhibit the activation of signaling pathways. When the expression of TM is decreased by GroEL stimulation, molecules in the PI3 K/Akt signaling axis are released and activated, resulting in increased migration and tube formation of EPCs. In addition, GroEL inhibits TM mRNA expression by activating miR-1248, miR-1291, and miR-5701. Losing the functions of miR-1248, miR-1291, and miR-5701 can effectively alleviate the GroEL-induced decrease in TM protein levels and inhibit the proangiogenic abilities of EPCs. These results were also confirmed in animal experiments. In conclusion, the intracellular domain of the TM of EPCs plays a negative regulatory role in the proangiogenic capabilities of EPCs, mainly through direct interaction between TM and PI3 K/Akt to inhibit the activation of signaling pathways. The effects of GroEL on tumor growth can be reduced by inhibiting the proangiogenic properties of EPCs through the inhibition of the expression of specific miRNAs.

Lpar1-mediated Effects in Endothelial Progenitor Cells Are Crucial for Lung Repair in Acute Respiratory Distress Syndrome/Acute Lung Injury.

Acute respiratory distress syndrome/acute lung injury (ARDS/ALI) involves acute respiratory failure characterized by vascular endothelial and lung alveolar epithelial injury. Endothelial progenitor cells (EPCs) can mediate vasculogenesis. However, the limitations of EPCs, such as low survival and differentiation, are believed to inhibit the effectiveness of autologous cell therapies. This study demonstrated that lysophosphatidic acid (LPA), a bioactive small molecule without immunogenicity, is involved in the survival and antiapoptotic effects in human umbilical cord mesenchymal stem cells. This study aimed to explore whether LPA improves the survival of EPCs, enhancing the cellular therapeutic efficacy in ARDS, and these results will expand the application of LPA in stem cells and regenerative medicine. LPA promoted the colony formation, proliferation, and migration of EPCs and upregulated the expression of vascular endothelial-derived growth factor (VEGF) in EPCs. LPA pretreatment of transplanted EPCs improved the therapeutic effect by increasing EPC numbers in the rat lungs. LPA enhanced EPC proliferation and migration through Lpar1 coupled to Gi/o and Gq/11, respectively. Activation of extracellular signal-related kinase 1/2, or ERK1/2, was related to LPA-induced EPC proliferation but not migration. LPA/Lpar1-mediated Gi/o protein was also shown to be involved in promoting VEGF expression and inhibiting IL-1α expression in EPCs. Low LPA concentrations are present after lung injury; thus, the restoration of LPA may promote endothelial cell homeostasis and lung repair in ARDS. Inhalation of LPA significantly promoted the homing of endogenous EPCs to the lung and reduced lung injury in both rats with LPS-induced ALI and Streptococcus pneumoniae-infected mice. Taken together, these data indicated that LPA/Lpar1-mediated effects in EPCs are involved in maintaining endothelial cell homeostasis and lung tissue repair under physiological conditions.

CXCR7 Agonist TC14012 Improves Angiogenic Function of Endothelial Progenitor Cells via Activating Akt/eNOS Pathway and Promotes Ischemic Angiogenesis in Diabetic Limb Ischemia.

Endothelial progenitor cells (EPCs) play a critical role in repairing damaged vessels and triggering ischemic angiogenesis, but their number is reduced and function is impaired under diabetic conditions. Improving EPC function has been considered a promising strategy to ameliorate diabetic vascular complications. In the present study, we aim to investigate whether and how CXCR7 agonist TC14012 promotes the angiogenic function of diabetic EPCs. High glucose (HG) treatment was used to mimic the hyperglycemia in diabetes. Tube formation, cell scratch recovery and transwell assay, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, and cleaved-caspase3 expression were used to evaluate the angiogenic capability, cell migration, and apoptosis of EPCs, respectively. Hind limb ischemia (HLI) model was used to appraise the ability of TC14012 in promoting diabetic ischemic angiogenesis in vivo. HG treatment impaired EPC tube formation and migration, and induced EPC apoptosis and oxidative damage, while TC14012 rescued tube formation and migration, and prevented HG-induced apoptosis and oxidative damage of EPCs. Furthermore, these beneficial effects of TC14012 on EPCs were attenuated by specific siRNAs against CXCR7, validating that CXCR7 is a functional target of TC14012 in EPCs. Mechanistic studies demonstrated that HG treatment reduced CXCR7 expression in EPCs, and impaired Akt and endothelial nitric oxide synthase (eNOS) phosphorylation and nitric oxide (NO) production; similarly, these signal impairments in HG-exposed EPCs could be rescued by TC14012. However, the protective effects of TC14012 on tube formation and migration, Akt and eNOS phosphorylation, and NO production in HG-treated EPCs were almost completely abolished by siRNAs against CXCR7 or Akt specific inhibitor wortmannin. More importantly, in vivo study showed that TC14012 administration enhanced blood perfusion recovery and angiogenesis in the ischemic hind limb and increased the EPC number in peripheral circulation of db/db mice, demonstrating the capability of TC14012 in promoting EPC mobilization and ischemia angiogenic function. TC14012 can prevent EPCs from HG-induced dysfunction and apoptosis, improve eNOS activity and NO production via CXCR7/Akt signal pathway, and promote EPC mobilization and diabetic ischemia angiogenesis.

Effects of adipose-derived stromal cells and endothelial progenitor cells on adipose transplant survival and angiogenesis.

BackgroundA paracrine mechanism is thought to mediate the proangiogenic capacity of adipose-derived stromal/stem cells (ASCs). However, the precise mechanism by which ASCs promote the formation of blood vessels by endothelial progenitor cells (EPCs) is unclear.MethodsThe EPCs-ASCs cocultures prepared in different ratios were subjected to tube formations assay to verify whether ASCs could directly participate in the tube genesis. The supernatant from cultured ASCs was used to stimulate EPCs to evaluate the effects on the angiogenic property of EPCs, as well as capacity for migration and invasion. A coculture model with transwell chamber were used to explore the regulation of angiogenesis markers expression in EPCs by ASCs. We then mixed ASCs with EPCs and transplanted them with adipose tissue into nude mice to evaluate the effects on angiogenesis in adipose tissue grafts.ResultsIn the EPCs-ASCs cocultures, the tube formation was significantly decreased as the relative abundance of ASCs increased, while the ASCs was found to migrate and integrated into the agglomerates formed by EPCs. The supernatant from ASCs cultures promoted the migration and invasion of EPCs and the ability to form capillary-like structures. The expression of multiple angiogenesis markers in EPCs were significantly increased when cocultured with ASCs. In vivo, ASCs combined with EPC promoted vascularization in the fat transplant. Immunofluorescence straining of Edu and CD31 indicated that the Edu labeled EPC did not directly participate in the vascularization inside the fat tissue.ConclusionsADSC can participate in the tube formation of EPC although it cannot form canonical capillary structures. Meanwhile, Soluble factors secreted by ASCs promotes the angiogenic potential of EPCs. ASCs paracrine signaling appears to promote angiogenesis by increasing the migration and invasion of EPCs and simultaneously upregulating the expression of angiogenesis markers in EPCs. The results of in vivo experiments showed that ASCs combined with EPCs significantly promote the formation of blood vessels in the fat implant. Remarkably, EPCs may promote angiogenesis by paracrine regulation of endogenous endothelial cells (ECs) rather than direct participation in the formation of blood vessels.

MicroRNA-126 and VEGF enhance the function of endothelial progenitor cells in acute myocardial infarction.

Previous studies have found that microRNA-126 (miR-126) overexpression can exert beneficial effects on endothelial function and angiogenesis. The role of miR-126 was previously reported to be by directly limiting the activities of negative regulators of the vascular endothelial growth factor (VEGF) pathway, such as PI3K regulation subunit 2 (PIK3R2). The aim of the present study was to investigate the role of the miR-126/PIK3R2/VEGF axis in endothelial progenitor cells (EPCs) under hypoxic conditions. An in vitro hypoxia model in EPCs was established by exposing EPCs to hypoxia (O2/N2/CO2, 1/94/5) for 72 h, before reverse transcription-quantitative PCR (RT-qPCR) and western blot analyzes were used to measure miR-126 and PIK3R2 expression in EPCs. The proliferation, migration and tube-forming ability of the transfected cells were measured using MTT, Transwell and tube formation assays, respectively. miR-126 expression was found to be lower in EPCs in the hypoxia group compared with that in the control group (P<0.01). The expression of PIK3R2, a direct target gene of miR-126, was found to be higher in the hypoxia group compared with that in the control group (P<0.01). miR-126 mimic and VEGF-plasmid co-transfection improved the proliferation, migration, tube-forming ability and restored the phosphorylation of AKT in EPCs under hypoxic conditions (all P<0.01). In addition, the effects of miR-126 mimic on hypoxia-induced EPCs were reversed by PIK3R2-plasmid co-transfection, whilst the effects of VEGF-plasmid were enhanced further by co-transfection with the miR-126 mimic. In conclusion, miR-126 promoted the functions of EPCs under hypoxic conditions by negatively targeting PIK3R2, whilst the combined overexpression of miR-126 and VEGF enhanced these aforementioned effects.

Circ-Klhl8 overexpression increased the therapeutic effect of EPCs in diabetic wound healing via the miR-212-3p/SIRT5 axis.

Previous studies found that hypoxic pretreatment of endothelial progenitor cells (EPCs) prior to transplantation had a greater therapeutic effect than untreated EPCs in promoting diabetic wound healing. However, the exact mechanism is uncertain. Here, circRNA expression in EPCs after hypoxic treatment was investigated. High-throughput sequencing was used to assess abnormal expression by EPCs of circular RNAs (circRNAs) following hypoxic pretreatment. Additionally, an in vivo full-thickness skin defect mouse model was used to assess the effects of transplanted EPCs on diabetic wound closure. Subsequently, the regulatory mechanism and targets were studied. The results showed that circ-Klhl8 overexpression suppressed hyper glucose-induced endothelial cell damage by activating autophagy. MiR-212-3p and SIRT5 were identified as the downstream targets of circ-Klhl8. Circ-Klhl8 overexpression promoted skin wound healing by regulating SIRT5-mediated autophagy. In conclusion, the study found that circ-Klhl8 overexpression increased the EPC therapeutic effect in promoting diabetic wound healing by targeting the miR-212-3p/SIRT5 axis.

MicroRNA-221 inhibits the transition of endothelial progenitor cells to mesenchymal cells via the PTEN/FoxO3a signaling pathway.

Coronary heart disease is one of the most common cardiovascular diseases worldwide and is often associated with vascular endothelial injury. Endothelial-mesenchymal transition (EndMT) is an important process in vascular endothelial injury. This study investigated the function of miR-221 in the EndMT process of endothelial progenitor cells (EPCs). Transforming growth factor beta (TGF-β1) was used to induce EndMT in EPCs, and SM22α expression was detected using immunocytochemistry. Western blot was used to detect alpha smooth muscle actin (αSMA) expression, and miR-221 function was evaluated using inhibitors or mimics of the miR-221 sequences that were transfected into EPCs. Reverse transcription polymerase chain reaction (RT-PCR) was used to detect the expression of miR-221 and western blot was used to detect the expression of αSMA, myocardin, phosphatase and tensin homolog (PTEN), p-FoxO3a, and FoxO3a in EPCs. Finally, the expression of the miR-221 target genes was determined using RT-PCR. The expression of SM22α and αSMA increased in EPCs treated with TGF-β1, while the expression of miR-221 was decreased in EPCs on the 5th day, when compared with the control. The expression of SM22α increased after inhibiting miR-221 in EPCs treated with TGF-β1 and this was reversed by the overexpression of miR-221. The expression of αSMA and myocardin was significantly increased after inhibiting miR-221 in EPCs treated with TGF-β1 and decreased in EPCs overexpressing miR-221. Conversely, PTEN was increased in TGF-β1-treated EPCs and decreased following the overexpression of miR-221. The decrease in phosphorylated-FoxO3a expression in EPCs was accompanied by an increase in αSMA expression, which was reversed in the presence of miR-221 mimics. This effect was nearly abolished following the addition of PTEN cDNA. The overexpression of miR-221 inhibits EndMT in EPCs, possibly by interacting with PTEN to regulate FoxO3a signaling, to facilitate the repair of the endothelium by EPCs.

The Inhibitory Effect of Lysophosphatidylcholine on Proangiogenesis of Human CD34+ Cells Derived Endothelial Progenitor Cells.

Increasing evidence reveals that lysophosphatidylcholine (LPC) is closely related to endothelial dysfunction. The present study aimed to investigate the mechanism of LPC in inhibiting the proangiogenesis and vascular inflammation of human endothelial progenitor cells (EPCs) derived from CD34+ cells. The early EPCs were derived from CD34+ hematopoietic stem cells whose purity was identified using flow cytometry analysis. The surface markers (CD34, KDR, CD31; VE-cadherin, vWF, eNOS) of EPCs were examined by flow cytometry analysis and immunofluorescence. RT-qPCR was used to detect the mRNA expression of inflammatory cytokines (CCL2, IL-8, CCL4) and genes associated with angiogenesis (VEGF, ANG-1, ANG-2) in early EPCs after treatment of LPC (10 μg/ml) or phosphatidylcholine (PC, 10 μg/ml, control). The angiogenesis of human umbilical vein endothelial cells (HUVECs) incubated with the supernatants of early EPCs was detected by a tube formation assay. The mRNA and protein levels of key factors on the PKC pathway (phosphorylated PKC, TGF-β1) were measured by RT-qPCR and western blot. The localization of PKC-β1 in EPCs was determined by immunofluorescence staining. We found that LPC suppressed the expression of CCL2, CCL4, ANG-1, ANG-2, promoted IL-8 expression and had no significant effects on VEGF expression in EPCs. EPCs promoted the angiogenesis of HUVECs, which was significantly inhibited by LPC treatment. Moreover, LPC was demonstrated to promote the activation of the PKC signaling pathway in EPCs. In conclusion, LPC inhibits proangiogenesis of human endothelial progenitor cells derived from CD34+ hematopoietic stem cells.

EFFECT OF FLAVONOIDS ON OXIDATIVE STRESS, APOPTOSIS, AND CELL MARKERS OF PERIPHERAL BLOOD-DERIVED ENDOTHELIAL PROGENITOR CELLS: AN IN VITRO STUDY

Objective: Circulating EPCs (endothelial progenitor cells) play a role in neovascularization and vascular repair. Oxidative stress impairs endothelial progenitor. Flavonoid is a phytochemical compound for antioxidant activity. Flavonoid effects toward oxidative stress, apoptosis, and expression of the cell markers on EPCs are not fully understood. This study was aimed to elucidate the effects of quercetin, kaempferol, and myricetin toward oxidative stress, apoptosis, and cell markers of peripheral blood-derived-EPCs.&#x0D; Methods: EPCs (endothelial progenitor cells) were isolated from peripheral blood mononuclear cells (PBMNCs) using cultivation under EPCs spesific media. Oxidative stress in EPCs was induced by H2O2 and then treated by quercetin, kaempferol, and myricetin. Cytotoxicity was measured by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay, while intracellular reactive oxygen species (ROS), apoptosis and characterization of cells, which expressed CD133 and KDR, was measured using flow cytometry.&#x0D; Results: Quercetin, kaempferol, and myricetin at concentration 12.50 µmol/l were not toxic on EPCs as the cells viability were 96.11±4.03%, 95.42±7.75%, and 94.22±9.49%, respectively. Flavonoids decreased intracellular ROS level in EPCs (quercetin: 14.38±1.47%, kaempferol: 20.21±6.25%, and myricetin: 13.88±4.02%) compared to EPCs treated with H2O2 (30.70%±1.04). Percetage of EPCs apoptosis was not significantly different among each treatment. Immunophenotyping showed the increasing of CD133 and KDR expression in EPCs treated with flavonoids.&#x0D; Conclusion: Quercetin, kaempferol, and myricetin were safe for EPCs, decreased ROS levels, and increased CD133 and KDR expression. However, the flavonoids did not significantly affect EPCs apoptosis.

GPR4 signaling is essential for the promotion of acid-mediated angiogenic capacity of endothelial progenitor cells by activating STAT3/VEGFA pathway in patients with coronary artery disease

BackgroundPatients with coronary artery disease (CAD) are characterized by a decline in vascular regeneration, which is related to the dysfunction of endothelial progenitor cells (EPCs). G-protein-coupled receptor 4 (GPR4) is a proton-sensing G-protein-coupled receptor (GPCR) that contributes to neovascularization in acidic microenvironments. However, the role of GPR4 in regulating the angiogenic capacity of EPCs from CAD patients in response to acidity generated in ischemic tissue remains completely unclear.MethodsThe angiogenic capacity of EPCs collected from CAD patients and healthy subjects was evaluated in different pH environments. The GPR4 function of regulating EPC-mediated angiogenesis was analyzed both in vitro and in vivo. The downstream mechanisms were further investigated by genetic overexpression and inhibition.ResultsAcidic environment prestimulation significantly enhanced the angiogenic capacity of EPCs from the non-CAD group both in vivo and in vitro, while the same treatment yielded the opposite result in the CAD group. Among the four canonical proton-sensing GPCRs, GPR4 displays the highest expression in EPCs. The expression of GRP4 was markedly lower in EPCs from CAD patients than in EPCs from non-CAD individuals independent of acid stimulation. The siRNA-mediated knockdown of GPR4 with subsequent decreased phosphorylation of STAT3 mimicked the impaired function of EPCs from CAD patients at pH 6.4 but not at pH 7.4. Elevating GPR4 expression restored the neovessel formation mediated by EPCs from CAD patients in an acidic environment by activating STAT3/VEGFA signaling. Moreover, the beneficial impact of GPR4 upregulation on EPC-mediated angiogenic capacity was abrogated by blockade of the STAT3/VEGFA signaling pathway.ConclusionsOur present study demonstrated for the first time that loss of GPR4 is responsible for the decline in proton sensing and angiogenic capacity of EPCs from CAD patients. Augmentation of GPR4 expression promotes the neovessel formation of EPCs by activating STAT3/VEGF signaling. This finding implicates GPR4 as a potential therapeutic target for CAD characterized by impaired neovascularization in ischemic tissues.

Beneficial Effects of Astragaloside IV-Treated and 3-Dimensional-Cultured Endothelial Progenitor Cells on Angiogenesis and Wound Healing.

Astragaloside IV (AS-IV) is a natural herb extract and a popular compound used in traditional Chinese medicine because of its effect on multiple biological processes, such as promotion of cell proliferation, improvement in cardiopulmonary and vascular function, and promotion of angiogenesis around wounds, leading to accelerated wound healing. Vascular regeneration primarily results from the differentiation of endothelial progenitor cells (EPCs). Biomedical acceleration of angiogenesis and differentiation of EPCs around the wound remain challenging. In this study, we treated human umbilical cord blood-derived EPCs with AS-IV and cultured them on 2-dimensional (tissue culture polystyrene) and 3-dimensional culture plates (3DPs). These cultured cells were then combined with human blood plasma gel and applied on the skin of nude mice in an attempt to repair full-thickness skin defects. The results show that using 3DP culture could increase vascular-related gene expression in EPCs. Furthermore, 12.5 μg/mL AS-IV-treaded EPCs were combined with plasma gels (P-3DP-EPC12.5) and showed enhanced vascular-related protein expression levels after 3 days of culture. Finally, P-3DP-EPC12.5s were used to repair full-thickness skin defects in nude mice, and we could register a wound healing rate greater than 90% by day 14. Based on these results, we concluded that we have developed a potential therapeutic approach for wound healing using plasma gel containing 3-dimensional surface-cultured AS-IV-treated EPCs.

Cigarette smoke extract affects methylation status and attenuates Sca-1 expression of mouse endothelial progenitor cell in vitro.

INTRODUCTIONEndothelial dysfunction appears in many smoking-related diseases, it is also an important pathophysiological feature. Endothelial progenitor cells (EPCs) are precursors of endothelial cells and have a crucial effect on the repair and maintenance of endothelial integrity. Sca-1 is not only common in bone marrow-derived hematopoietic stem cells (HSCs), but it is also expressed in nonhematopoietic organs by tissue-resident stem and progenitor cells. The aim of this study is to investigate the impact of cigarette smoke extract (CSE) on the function of bone marrow-derived EPCs and the expression level of Sca-1 in EPCs, and also whether the methylation of Sca-1 is involved in EPC dysfunction.METHODSWe measured EPC capacities including adhesion, secretion and proliferation, the concentration of endothelial nitric oxide synthase (eNOS) and apoptosis-inducing factor (AIF) in cell culture supernatant, and also Sca-1 expression and promoter methylation in EPCs induced by CSE. Decitabine (Dec) was applied to test whether it could alter the impact caused by CSE.RESULTSThe adhesion, proliferation and secretion ability of EPCs can be induced to be decreased by CSE in vitro, accompanied by decreased concentrations of AIF and eNOS in cell culture supernatant and decreased Sca-1 expression in EPCs. In addition, Dec could partly attenuate the impact described above. There were no significant differences in the quantitative analysis of Sca-1 promoter methylation among different groups.CONCLUSIONSThe decreased Sca-1 expression was related to EPC dysfunction induced by CSE. EPC dysfunction resulting from CSE may be related to methylation mechanism, but not the methylation of Sca-1 promoter.

MiR-17-5p promotes the endothelialization of endothelial progenitor cells to facilitate the vascular repair of aneurysm by regulating PTEN-mediated PI3K/AKT/VEGFA pathway

ABSTRACT The endothelialization of endothelial progenitor cells (EPCs) was proven to facilitate the vascular repair of aneurysm. MiR-17-5p regulated angiogenesis in various cancers. This research focused on exploring the effect of miR-17-5p on EPCs and the vascular repair of aneurysm. In vivo study: the aneurysm rat model was established and treated with AgomiR-17-5p; the histopathology of aneurysm tissues was examined by hematoxylin-eosin staining; and the level of EPCs in the aneurysm tissues and peripheral blood of rats were evaluated by immunofluorescence and flow cytometry, respectively. In vitro study: EPCs were cultured and identified using flow cytometry; the target of miR-17-5p was proven by dual-luciferase reporter assay; after transfection, the viability, migration, and tube formation of the EPCs were detected by MTT, wound healing, and tube formation assays, respectively; the expressions of VEGFA and factors related to PTEN-mediated PI3K/AKT pathway were detected by ELISA, qPCR, or Western blot as needed. In vivo study: miR-17-5p overexpression promoted the vascular repair in aneurysm rats and increased the level of EPCs in the aneurysm tissues and peripheral blood of the rats. In vitro study: miR-17-5p overexpression promoted the viability, migration, and tube formation of EPCs, up-regulated the expressions of VEGFA, p-PI3K, and p-AKT, and down-regulated the PTEN expression in EPCs; miR-17-5p silencing did the opposite; PTEN was targeted by miR-17-3p and further abrogated the effects of miR-17-5p overexpression on EPCs. MiR-17-5p promoted the endothelialization of EPCs to facilitate the vascular repair of aneurysm by regulating PTEN-mediated PI3K/AKT/VEGFA pathway.

Aerobic exercise induces tumor suppressor p16INK4a expression of endothelial progenitor cells in human skeletal muscle.

Aerobic exercise induces oxidative stress and DNA damage, nevertheless, lowers cancer incidence. It remains unclear how genetic stability is maintained under this condition. Here, we examined the dynamic change of the tumor suppressor p16INK4a in cells of skeletal muscle among young men following 60-min of aerobic cycling at 70% maximal oxygen consumption (V̇O2max). Rg1 (5 mg, an immunostimulant ginsenoside) and placebo (PLA) were supplemented 1 h before exercise. Data from serial muscle biopsies shows unchanged p16INK4a+ cells after exercise followed by a considerable increase (+21-fold) in vastus lateralis muscle 3 h later. This increase was due to the accumulation of endothelial progenitor cells (p16INK4a+/CD34+) surrounding myofibers and other infiltrated nucleated cells (p16INK4a+/CD34-) in necrotic myofibers. During the Rg1 trial, acute increases of p16INK4a+ cells in the muscle occurred immediately after exercise (+3-fold) and reversed near baseline 3 h later. Rg1 also lowered IL-10 mRNA relative to PLA 3 h after exercise. Post-exercise increases in VEGF mRNA and CD163+ macrophages were similar for PLA and Rg1 trials. Conclusion: The marked increases in p16INK4a protein expression of endothelial progenitor cells in skeletal muscle implicates a protective mechanism for maintaining genetic stability against aerobic exercise. Rg1 accelerates resolution of the exercise-induced stress response.

PGC-1α gene transfer restores adhesion and reendothelialization of endothelial progenitor cells from patients with hypertension.

Endothelial progenitor cells (EPCs) play an important role in endothelial vascular development and endothelial repair. The upregulation of functional gene expression in EPCs may contribute to the maintenance of EPC-based endothelial repair. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a powerful regulator of mitochondrial biogenesis and antioxidant defense, but its impact on early EPCs remains poorly understood. This study was designed to investigate whether decline in PGC-1α expression impairs in vitro adhesion, migration, and in vivo reendothelialization capacity of early EPCs from patients with hypertension. We engineered an over-expression of PGC-1α within EPCs from hypertensive patients, which were transduced with an adenoviral vector encoding the human PGC-1α gene. Then we tested the migration and adhesion function of EPCs in vitro and endothelium-reparative capacity in vivo with a nude mouse model of carotid artery injury. Our data revealed for the first time that PGC-1α expression of EPCs is lower in hypertensive patients than that in healthy subjects. Meanwhile, the in vitro adhesion and migration function, in vivo endothelial repair capacity of early EPCs were significantly reduced in hypertensive patients compared with normal subjects. Furthermore, PGC-1α gene transfer contributes to increased adhesion in vitro and enhanced endothelium-reparative capacity in vivo of EPCs from hypertensive patients through the augmented expression of PGC-1α. Thus, upregulation of PGC-1α expression of EPCs may be a novel complementary therapeutic target to increase endothelium-reparative capacity in hypertensive patients.

Exendin-4 reverses high glucose-induced endothelial progenitor cell dysfunction via SDF-1β/CXCR7-AMPK/p38-MAPK/IL-6 axis.

Exendin-4, a glucagon-like peptide-1 (GLP-1) analog, has been used for treating diabetes mellitus (DM). However, its effects on improving the dysfunction of high glucose (HG)-induced endothelial progenitor cells (EPCs) remain unclear. The present study explored the effects of Exendin-4 on improving dysfunction of EPCs and the underlying mechanism. EPCs were isolated from SD rats and identified by flow cytometry. Next, the EPCs were treated by HG and high or low concentration of Exendin-4, and cell viability, migration and tube formation were, respectively, examined by performing MTT assay, wound-healing assay and tube formation assay. Interleukin-6 (IL-6) secretion was measured by enzyme-linked immunosorbent assay (ELISA). The protein expressions of relative stromal-derived growth factor-1β (SDF-1β), C-X-C chemokine receptor type 7 (CXCR7), AMP-activated protein kinase (AMPK), p38 and expressions of CXCR7 and IL-6 in EPCs were measured by Western blot. The cell behaviors of EPCs treated by HG and Exendin-4 with or without silencing of CXCR7 and IL-6 were detected. Exendin-4 reversed the inhibitory effects of HG on viability, migration and tube formation of EPCs and on SDF-1β/CXCR7-AMPK pathway in EPCs in a dose-dependent manner. Moreover, Exendin-4 promoted the effects of HG on IL-6 level in EPCs through the promotion of p38-MAPK phosphorylation and reduction of cleaved caspase-3 protein expressions in EPCs. However, silencing of CXCR7 and IL-6 reversed the effects of Exendin-4 on cell behaviors, inactivated SDF-1β/CXCR7-AMPK pathway and increased cleaved caspase-3 expression in EPCs. Exendin-4 could ameliorate HG-induced EPC dysfunction through regulating the production of IL-6 via SDF-1β/CXCR7-AMPK/p38-MAPK axis.