Matrigel Tube Formation Research Articles

Thymosin β4 promotes the survival and angiogenesis of transplanted endothelial progenitor cells in the infarcted myocardium.

The survival of transplanted stem cells in ischemic tissue is poor. In the present study, the effects of thymosin β4 (Tβ4) on the survival and angiogenesis of endothelial progenitor cells (EPCs) and improvement in cardiac functions after transplantation of Tβ4-treated EPCs in the infarcted myocardium were investigated. EPCs were isolated from bone marrow of adult male rats and incubated in Endothelial Basal Medium-2. Then the cells were treated with Tβ4 at different concentrations (0.05, 0.1 and 0.2 µM), and cells incubated with DMEM were set as controls. MTT assay, Transwell assay and tube formation in Matrigel were used to detect cell viability, migration and angiogenesis, respectively. For examining the protective effect of Tβ4 on EPCs, the cells were also incubated in the condition of hypoxia and serum deprivation. p-Akt expression was also examined using western blot analysis. Rat models of myocardial infarction (MI) were established by ligation of the anterior descending branch of the left coronary artery. At four weeks after intramyocardial injection of Tβ4-treated EPCs, the changes in cardiac functions, size of the scar tissue and density of microvessels were examined by echocardiography, Masson's trichrome staining, immunohistochemistry and fluorescence in situ hybridization (FISH) for the Y-chromosome. Tβ4 enhanced EPC viability, protected the cells from apoptosis in hypoxia and serum deprivation, and promoted the proliferation and migration of the cells and formation of capillary-like structures in the cells. Moreover, Tβ4 increased p-Akt expression in the cells. The cytoprotective and proangiogenic effects of Tβ4 were in a dose-dependent manner. Tβ4-treated EPCs improved cardiac function, enhanced the repair of the infarcted myocardium, and promoted angiogenesis after transplantation in the infarcted myocardium. In conclusion, pretreatment of EPCs with Tβ4 is a novel strategy for the repair of ischemic tissue after transplantation in MI.

Activation of CD137 Signaling Promotes Angiogenesis in Atherosclerosis via Modulating Endothelial Smad1/5-NFATc1 Pathway.

BackgroundExcessive angiogenesis is a key feature of vulnerable atherosclerotic plaques, and is considered an independent predictor of cardiovascular risk. CD137 signaling has previously been shown to be involved in atherosclerosis. However, the possible role of CD137 signaling in regulating angiogenesis has not been reported.Methods and ResultsApolipoprotein E‐deficient (ApoE−/−) mice were used as the in vivo model of atherosclerosis. Masson and immunohistochemical analysis of atherosclerotic plaques and Matrigel plug assay were used to evaluate the angiogenesis. Human umbilical vein endothelial cells and mouse brain microvascular endothelial cells were used as in vitro and ex vivo models to study how CD137 signaling affects angiogenesis. Matrigel tube formation assay, mouse aortic ring angiogenesis assay, and migration and proliferation assay were employed to assess angiogenesis. Western blot was used to detect protein expression. We found increased neovessel formation in atherosclerotic plaques of ApoE−/− mice treated with agonist anti‐CD137 antibody. Activation of CD137 signaling induced angiogenesis, endothelial proliferation, and endothelial cell migration. CD137 signaling activates the pro‐angiogenic Smad1/5 pathway, induces the phosphorylation of Smad1/5 and nuclear translocation of p‐Smad1/5, which in turn promotes the expression and translocation of NFATc1. Blocking CD137 signaling with inhibitory anti‐CD137 antibody could inhibit this activation and attenuated agonist anti‐CD137 antibody‐induced angiogenesis.ConclusionsThese findings suggest that CD137 signaling is a new regulator of angiogenesis by modulating the Smad1/5‐NFATc1 pathway.

Angiogenic characteristics of human stromal vascular fraction in ischemic hindlimb

IntroductionIn this study, we sought to characterize the angio-vasculogenic property of human adipose tissue-derived stromal vascular fraction (SVF) and to determine the therapeutic potential of SVF in the context of experimental ischemia. Although human SVF is used for cell therapy, its angiogenic and vasculogenic characteristics have not been fully elucidated. Methods and resultsWe conducted flow cytometry, microarray, quantitative (q)-PCR, Matrigel tube formation assays and in vivo therapeutic assays using an ischemic hind limb mouse model. Gene/micro RNA microarray, quantitative (q)-PCR results revealed that the representative pro-angiogenic factors were highly upregulated in SVF compared with human adipose-derived mesenchymal stem cells (ASCs). In addition, SVF exhibited high expression of endothelium-specific genes and showed robust in vitro micro-vascular formation. SVF was transplanted into ischemic mouse hind limbs and compared with ASC transplantation. SVF transplantation prevented limb loss and augmented blood perfusion, indicating that SVF promotes neovascularization in hind limb ischemia. Transplanted SVF showed high vasculogenic potential in vivo compared with transplanted ASCs. ConclusionsOur data indicate that SVF has remarkable therapeutic effects on hind limb ischemia via robust angiogenic and vasculogenic activity.

Transplantation of Rat Mesenchymal Stem Cells Overexpressing Hypoxia-Inducible Factor 2α Improves Blood Perfusion and Arteriogenesis in a Rat Hindlimb Ischemia Model.

Mesenchymal stem cells (MSCs) have been increasingly tested in cell-based therapy to treat numerous diseases. Genetic modification to improve MSC behavior may enhance posttransplantation outcome. This study aims to test the potential therapeutic benefits of rat bone marrow MSCs overexpressing hypoxia-inducible factor 2α (rMSCsHIF-2α) in a rat hindlimb ischemia model. PBS, rMSCs, or rMSCsHIF-2α were injected into rat ischemic hindlimb. Compared with the injection of PBS or rMSCs, transplantation of rMSCsHIF-2α significantly improved blood perfusion, increased the number of vessel branches in the muscle of the ischemic hindlimb, and improved the foot mobility of the ischemic hindlimb (all P < 0.05). rMSCHIF-2α transplantation also markedly increased the expression of proangiogenic factors VEGF, bFGF, and SDF1 and Notch signaling proteins including DII4, NICD, Hey1, and Hes1, whereas it reduced the expression of proapoptotic factor Bax in the muscle of the ischemic hindlimb. Overexpression of HIF-2α did not affect rMSC stemness and proliferation under normoxia but significantly increased rMSC migration and tube formation in matrigel under hypoxia (all P < 0.05). RMSCsHIF-2α stimulated endothelial cell invasion under hypoxia significantly (P < 0.05). Genetic modification of rMSCs via overexpression of HIF-2α improves posttransplantation outcomes in a rat hindlimb ischemia model possibly by stimulating proangiogenic growth factors and cytokines.

Platelet-Derived Growth Factor Receptor-Positive Pericytic Cells of White Adipose Tissue from Critical Limb Ischemia Patients Display Mesenchymal Stem Cell-Like Properties.

BackgroundThe pericytes in the blood vessel wall have recently been identified to be important in regulating vascular formation, stabilization, remodeling, and function. We isolated and identified pericyte-like platelet-derived growth factor receptor beta-positive (PDGFRβ+) cells from the stromal vascular fraction (SVF) of adipose tissue from critical limb ischemia (CLI) patients and investigated their potential as a reliable source of stem cells for cell-based therapy.MethodsDe-identified subcutaneous fat tissues were harvested after amputation in CLI patients. Freshly isolated SVF cells and culture-expanded adipose-derived stem cells (ADSCs) were quantified using flow cytometry. A matrigel tube formation assay and multi-lineage differentiation were performed to assess pericytic and mesenchymal stem cell (MSC)-like characteristics of PDGFRβ+ ADSCs.ResultsPDGFRβ+ cells were located in the pericytic area of various sizes of blood vessels and coexpressed mesenchymal stem cell markers. PDGFRβ+ cells in freshly isolated SVF cells expressed a higher level of stem cell markers (CD34 and CXCR4) and mesenchymal markers (CD13, CD44, CD54, and CD90) than PDGFRβ– cells. In vitro expansion of PDGFRβ+ cells resulted in enrichment of the perivascular mesenchymal stem-like (PDGFRβ+/CD90+/CD45–/CD31–) cell fractions. The Matrigel tube formation assay revealed that PDGFRβ+ cells were located in the peritubular area.ConclusionsPDGFRβ+ ADSCs cells demonstrated a good multilineage differentiation potential. Pericyte-like PDGFRβ+ cells from the SVF of adipose tissue from CLI patients had MSC-like characteristics and could be amplified by in vitro culture with preservation of their cell characteristics. We believe PDGFRβ+ cells in the SVF of adipose tissue can be used as a reliable source of stem cells even in CLI patients.

Up-Regulated Expression of Matrix Metalloproteinases in Endothelial Cells Mediates Platelet Microvesicle-Induced Angiogenesis

Background/Aims: Platelet microvesicles (PMVs) contribute to angiogenesis and vasculogenesis, but the mechanisms underlying these contributions have not been fully elucidated. In the present study, we investigated whether PMVs regulate the angiogenic properties of endothelial cells (ECs) via mechanisms extending beyond the transport of angiogenic regulators from platelets. Methods: In vitro Matrigel tube formation assay and in vivo Matrigel plug assay were used to evaluate the pro-angiogenic activity of PMVs. The effects of PMVs on the migration of human umbilical vein endothelial cells (HUVECs) were detected by transwell assay and wound-healing assay. Real-time PCR and western blot were conducted to examine mRNA and protein expression of pro-angiogenic factors in HUVECs. Matrix metalloproteinase (MMP) activity was assayed by gelatin zymography. Moreover, the effects of specific MMP inhibitors were tested. Results: PMVs promoted HUVEC capillary-like network formation in a dose-dependent manner. Meanwhile, PMVs dose-dependently facilitated HUVEC migration. Levels of MMP-2 and MMP-9 expression and activity were up-regulated in HUVECs stimulated with PMVs. Inhibition of MMPs decreased their pro-angiogenic and pro-migratory effects on HUVECs. Moreover, we confirmed the pro-angiogenic activity of PMVs in vivo in mice with subcutaneous implantation of Matrigel, and demonstrated that blockade of MMPs attenuated PMV-induced angiogenesis. Conclusion: The findings of our study indicate that PMVs promote angiogenesis by up-regulating MMP expression in ECs via mechanism extending beyond the direct delivery of angiogenic factors.

Extracellular Signal-Regulated Kinase 5 is Required for Low-Concentration H2O2-Induced Angiogenesis of Human Umbilical Vein Endothelial Cells.

Background. The aim of this study was to assess the effects of low concentrations of H2O2 on angiogenesis of human umbilical vein endothelial cells (HUVECs) in vitro and explore the underlying mechanisms. Methods. HUVECs were cultured and stimulated with different concentrations of H2O2. Flow cytometric analysis was used to select an optimal concentration of H2O2 for the following experiments. Cell proliferation, migration, and tubule formation were evaluated by Cell Counting Kit-8 (CCK-8) assays, scratch wound assays, and Matrigel tubule formation assays, respectively. For gain and loss of function studies, constitutively active MEK5 (CA-MEK5) and ERK5 shRNA lentiviruses were used to activate or knock down extracellular signal-regulated kinase 5 (ERK5). Results. We found that low concentrations of H2O2 promoted HUVECs proliferation, migration, and tubule formation. ERK5 in HUVECs was significantly activated by H2O2. Enhanced ERK5 activity significantly amplified the proangiogenic effects of H2O2; in contrast, ERK5 knock-down abrogated the effects of H2O2. Conclusions. Our results confirmed that low concentrations of H2O2 promoted HUVECs angiogenesis in vitro, and ERK5 is an essential mediator of this process. Therefore, ERK5 may be a potential therapeutic target for promoting angiogenesis and improving graft survival.

Cryptotanshinone inhibits VEGF-induced angiogenesis by targeting the VEGFR2 signaling pathway

ObjectiveAnti-angiogenesis has been proposed as an important strategy for angiogenesis-related diseases. Cryptotanshinone (CPT), an active component of Salvia miltiorrhiza, may be a potential inhibitor of angiogenesis. However, the molecular mechanisms underlying its anti-angiogenic activities remain poorly understood. This study is to investigate the effects of CPT on VEGF-induced angiogenesis and VEGFR2 signaling pathway in human umbilical vein endothelial cells (HUVECs). MethodsHUVECs were treated with different concentration of CPT (5–20μmol/L) and the viability, endothelial cell migration, invasion, and tubular-like structure formation of HUVECs were detected by MTT, wound-healing migration, Transwell invasion and Matrigel tube formation assays, respectively. To assess the effect of CPT on VEGFR2 signaling pathway, VEGF-induced phosphorylation of VEGFR2 and its downstream molecules, including ERK1/2, p90RSK, Src and FAK were analyzed by Western blot. ResultsCPT significantly suppressed VEGF-induced cells proliferation, migration, invasion, and tubular-like structure formation in HUVECs in a dose- and time-dependent manner. Western blot results revealed that CPT significantly suppressed VEGF-induced phosphorylation of VEGFR2 and its key downstream protein kinases, including p-ERK1/2, p-p90RSK, pY416-Src and pY576/577-FAK, which are responsible for endothelial cell migration, proliferation, and survival. ConclusionOur study suggested that CPT potently inhibits VEGF-induced angiogenesis by suppressing VEGFR2 activation and its downstream Src/FAK and ERK1/2 signaling pathways in HUVECs, highlighting the therapeutic potential for the treatment of angiogenesis-related diseases.

JAK2V617F - Positive Endothelial Cells Display Pro-Thrombotic Characteristics

Background: Clinical complications of BCR-ABL1-negative Myeloproliferative Neoplasms (MPNs) include mainly vascular events and on longer term transformation to Myelofibrosis (MF) or acute leukemia. MPNs are also associated with neo-angiogenesis leading to extramedullary hematopoiesis and increased vascularity in the spleen and bone marrow. The most frequent molecular alteration present in hematopoietic cells is the JAK2V617F mutation, which has also been detected in hepatic Endothelial Cells (ECs) of MPN patients with Budd-Chiari syndrome (BCS) and in ECs derived from patients' splenic capillaries. The consequences of the presence of the JAK2V617F mutation into the endothelial lineage are not known although these cells play an important role in thrombosis.Methods: Isogenic JAK2 wild-type (WT) and JAK2V617F mutant induced pluripotent stem cells (iPSC) were derived from an MPN patient. The reprogrammed clonal cells were induced to differentiate toward mesoderm for 3 days and then driven toward the endothelial lineage using Stem-Pro medium, Vascular Endothelial Growth Factor (VEGF) and Forskolin. Enriched CD34+/CD144+ progenitors were then matured in VEGF-supplemented Stem-Pro medium for 5 days before being cultured in the EGM-2 specific EC medium in the presence of the TGF-β inhibitor SB-431542. Cells were harvested and tested for specific surface markers by flow cytometry before expanding them; passages 3 to 6 were used for further characterization and functional studies. Transcriptomic analysis was performed in triplicate from two independent endothelial differentiation experiments using Affymetrix HTA 2.0 gene expression arrays.Results: Phenotypically, the endothelial-like cells obtained after differentiation from both mutant and WT JAK2 iPSC displayed a classical EC morphology and were positive for CD34 and EC markers (CD144, CD309, CD31 and ICAM-1). Such characteristics were conserved for at least 6 rounds of cell passaging. TNF-α treatment increased ICAM-1 cell surface levels and induced the expression of VCAM-1, as observed in other EC models. Our iPS-derived cells were also responsive to VEGF, which induced cellular proliferation and angiogenesis demonstrated by tube formation in Matrigel with both JAK2V617F and WT ECs. As expected, JAK2V617F ECs exhibited higher levels of phosphorylated forms of JAK2, STAT3 and Akt in a serum and growth factor-reduced medium, showing that, as in hematopoietic cells, the presence of the mutation increases basal intracellular signaling. Interestingly, Weibel-Palade bodies detection by confocal microscopy revealed a more important amount of Von Willebrand factor (vWF) in JAK2V617F ECs (2-fold increase), suggesting a higher pro-thrombotic potential for these cells. Basal surface expression of the adhesion molecule ICAM-1 was also clearly increased (1.8-fold) compared to WT ECs suggesting that JAK2V617F ECs may be more prone to recruit activated leukocytes expressing LFA-1, the ICAM-1 receptor. Gene expression microarrays analysis confirmed a significantly higher expression of cell adhesion molecules involved in leukocyte or platelet adhesion in JAK2V617F vs. WT ECs (ICAM-1, VCAM-1, or P-selectin), together with several inflammatory chemokines (IL8, CXCL1, or CXCL5), chemokine receptors (CXCR4 or IL7R) and extracellular matrix modulators (Periostin, Tenascin C, Lysyl Oxidase, or MMP-10) . Finally, Gene Set Enrichment Analysis pointed out gene sets induced in situations of inflammation, response to cytokines and hypoxia. These results could be in agreement with an activated endothelium, leukocyte recruitment and vascular remodeling.Conclusion: Previous discovery of JAK2V617F-positive endothelial cells in the splanchnic vasculature of patients with BCS or MF was of particular interest because of the well-known association between thrombosis and MPN. In this work we first demonstrate that the presence of JAK2V617F doesn't impair endothelial differentiation from stem/progenitor cells. Moreover, JAK2V617F-mutant ECs display features of pro-inflammatory and pro-thrombotic EC activation, which we are currently further characterizing with additional functional studies. Finally, this iPSC model may represent an effective screening tool for molecules antagonizing the pro-thrombotic events in a JAK2V617F context. DisclosuresKiladjian:Novartis: Honoraria, Research Funding; AOP Orphan: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Hypoxia-induced responses by endothelial colony-forming cells are modulated by placental growth factor.

BackgroundEndothelial colony-forming cells (ECFCs), also termed late outgrowth endothelial cells, are a well-defined circulating endothelial progenitor cell type with an established role in vascular repair. ECFCs have clear potential for cell therapy to treat ischaemic disease, although the precise mechanism(s) underlying their response to hypoxia remains ill-defined.MethodsIn this study, we isolated ECFCs from umbilical cord blood and cultured them on collagen. We defined the response of ECFCs to 1% O2 exposure at acute and chronic time points.ResultsIn response to low oxygen, changes in ECFC cell shape, proliferation, size and cytoskeleton phenotype were detected. An increase in the number of senescent ECFCs also occurred as a result of long-term culture in 1% O2. Low oxygen exposure altered ECFC migration and tube formation in Matrigel®. Increases in angiogenic factors secreted from ECFCs exposed to hypoxia were also detected, in particular, after treatment with placental growth factor (PlGF). Exposure of cells to agents that stabilise hypoxia-inducible factors such as dimethyloxalylglycine (DMOG) also increased PlGF levels. Conditioned medium from both hypoxia-treated and DMOG-treated cells inhibited ECFC tube formation. This effect was reversed by the addition of PlGF neutralising antibody to the conditioned medium, confirming the direct role of PlGF in this effect.ConclusionsThis study deepens our understanding of the response of ECFCs to hypoxia and also identifies a novel and important role for PlGF in regulating the vasculogenic potential of ECFCs.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-016-0430-0) contains supplementary material, which is available to authorized users.

Histone Deacetylase 5 Is Overexpressed in Scleroderma Endothelial Cells and Impairs Angiogenesis via Repression of Proangiogenic Factors

Vascular dysfunction represents a disease-initiating event in systemic sclerosis (SSc; scleroderma). Results of recent studies suggest that epigenetic dysregulation impairs normal angiogenesis and can result in abnormal patterns of blood vessel growth. Histone deacetylases (HDACs) control endothelial cell (EC) proliferation and regulate EC migration. Specifically, HDAC-5 appears to be antiangiogenic. This study was undertaken to test whether HDAC-5 contributes to impaired angiogenesis in SSc by repressing proangiogenic factors in ECs. Dermal ECs were isolated from patients with diffuse cutaneous SSc and healthy controls. Angiogenesis was assessed using an in vitro Matrigel tube formation assay. An assay for transposase-accessible chromatin using sequencing (ATAC-seq) was performed to assess and localize the genome-wide effects of HDAC5 knockdown on chromatin accessibility. The expression of HDAC5 was significantly increased in ECs from patients with SSc compared to healthy control ECs. Silencing of HDAC5 in SSc ECs restored normal angiogenesis. HDAC5 knockdown followed by ATAC-seq assay in SSc ECs identified key HDAC5-regulated genes involved in angiogenesis and fibrosis, such as CYR61, PVRL2, and FSTL1. Simultaneous knockdown of HDAC5 in conjunction with either CYR61, PVRL2, or FSTL1 inhibited angiogenesis in SSc ECs. Conversely, overexpression of these genes individually led to an increase in tube formation as assessed by Matrigel assay, suggesting that these genes play functional roles in the impairment of angiogenesis in SSc. Several novel HDAC5-regulated target genes associated with impaired angiogenesis were identified in SSc ECs by ATAC-seq. The results of this study provide a potential link between epigenetic regulation and impaired angiogenesis in SSc, and identify a novel mechanism for the dysregulated angiogenesis that characterizes this disease.

Therapeutic angiogenesis induced by human umbilical cord tissue-derived mesenchymal stromal cells in a murine model of hindlimb ischemia.

BackgroundMesenchymal stem cells derived from human umbilical cord tissue, termed UCX®, have the potential to promote a full range of events leading to tissue regeneration and homeostasis. The main goal of this work was to investigate UCX® action in experimentally induced hindlimb ischemia (HLI).MethodsUCX®, obtained by using a proprietary technology developed by ECBio (Amadora, Portugal), were delivered via intramuscular injection to C57BL/6 females after unilateral HLI induction. Perfusion recovery, capillary and collateral density increase were evaluated by laser doppler, CD31 immunohistochemistry and diaphonisation, respectively. The activation state of endothelial cells (ECs) was analysed after EC isolation by laser capture microdissection microscopy followed by RNA extraction, cDNA synthesis and quantitative RT-PCR analysis. The UCX®-conditioned medium was analysed on Gallios flow cytometer. The capacity of UCX® in promoting tubulogenesis and EC migration was assessed by matrigel tubule formation and wound-healing assay, respectively.ResultsWe demonstrated that UCX® enhance angiogenesis in vitro via a paracrine effect. Importantly, after HLI induction, UCX® improve blood perfusion by stimulating angiogenesis and arteriogenesis. This is achieved through a new mechanism in which durable and simultaneous upregulation of transforming growth factor β2, angiopoietin 2, fibroblast growth factor 2, and hepatocyte growth factor, in endothelial cells is induced by UCX®.ConclusionsIn conclusion, our data demonstrate that UCX® improve the angiogenic potency of endothelial cells in the murine ischemic limb suggesting the potential of UCX® as a new therapeutic tool for critical limb ischemia.

Abstract 045: Endothelial Colony Forming Cells Dysfunction Relates to Cardiovascular Alterations in Preterm Born Adults

Endothelial colony-forming cell (ECFC), a subtype of endothelial progenitor cells with high clonogenic and proliferative capacity, is present in cord and peripheral blood, participating in neovessel formation and regeneration. Cord blood ECFCs have impaired bioactivity in pregnancy complications and preterm (PT) birth. Dysfunction of cord blood ECFC is also related to complications of prematurity such as bronchopulmonary dysplasia. Although cardiovascular alterations, such as high blood pressure (BP) and left ventricular (LV) dysfunction, occur in PT subjects during adulthood, whether ECFC dysfunction beyond the neonatal period relates to such alterations is not known. OBJECTIVE: We aim in this study to assess if ECFC function relates to cardiovascular alterations in PT born adults. METHODS: Peripheral blood mononuclear cells from 30 young adults (21-28 years old) born very PT (&lt;29 weeks gestation) and 30 at term (T, ≥37 weeks gestation) were separated by density gradient and cultured to ECFC colony formation. ECFC proliferative and angiogenic function were assessed in vitro by modified thymidine analogue (EdU) incorporation and tube formation in Matrigel. BP was measured by 24h monitor and LV mass index (g/cm 2 ) by ultrasound imaging. All analyses were performed blind; correlations were significant when p&lt;0.05. RESULTS: The proportion of early (&lt;15 days) and late (≥15 days) time for ECFC colony formation was different between PT and T, with a higher frequency for late growth or no colony in the PT born group. Time to colony formation inversely correlated with ECFC proliferation rate (r=-0.57, r 2 =0.32) and tube formation (r=-0.57, r 2 =0.33) in PT, which shows ECFC dysfunction in those PT subjects with late colony formation, with no significant correlations in T. Additionally, time to colony formation has positively related to systolic BP (r=0.54, r 2 =0.29) and LV mass index (r=0.49, r 2 =0.24) in PT born subjects. CONCLUSION: Our findings demonstrate, for the first time, an association between dysfunctional circulating ECFCs and cardiovascular alterations in adults born PT. We also show that ECFC dysfunction, in PT adults, significantly relates to important cardiovascular risk factors such as high BP and increased LV mass.

Nitrative Stress Participates in Endothelial Progenitor Cell Injury in Hyperhomocysteinemia.

In order to investigate the role of nitrative stress in vascular endothelial injury in hyperhomocysteinemia (HHcy), thirty healthy adult female Wistar rats were randomly divided into three groups: control, hyperhomocysteinemia model, and hyperhomocysteinemia with FeTMPyP (peroxynitrite scavenger) treatment. The endothelium-dependent dilatation of thoracic aorta in vitro was determined by response to acetylcholine (ACh). The histological changes in endothelium were assessed by HE staining and scanning electron microscopy (SEM). The expression of 3-nitrotyrosine (NT) in thoracic aorta was demonstrated by immunohistochemistry and immunofluorescence, and the number of circulating endothelial progenitor cells (EPCs) was quantified by flow cytometry. Hyperhomocysteinemia caused significant endothelial injury and dysfunction including vasodilative and histologic changes, associated with higher expression of NT in thoracic aorta. FeTMPyP treatment reversed these injuries significantly. Further, the effect of nitrative stress on cultured EPCs in vitro was investigated by administering peroxynitrite donor (3-morpholino-sydnonimine, SIN-1) and peroxynitrite scavenger (FeTMPyP). The roles of nitrative stress on cell viability, necrosis and apoptosis were evaluated with 3-(4,5-dimethylthiazol)-2,5-diphenyl tetrazolium (MTT) assay, lactate dehydrogenase (LDH) release assay and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay, respectively. Also, the phospho-eNOS expression and tube formation in Matrigel of cultured EPCs was detected. Our data showed that the survival of EPCs was much lower in SIN-1 group than in vehicle group, both the apoptosis and necrosis of EPCs were much more severe, and the p-eNOS expression and tube formation in Matrigel were obviously declined. Subsequent pretreatment with FeTMPyP reversed these changes. Further, pretreatment with FeTMPyP reversed homocysteine-induced EPC injury. In conclusion, this study indicates that nitrative stress plays a role in vascular endothelial injury in hyperhomocysteinemia, as well as induces endothelial progenitor cell injury directly.

Cross-talk between macrophages and smooth muscle cells impairs collagen and metalloprotease synthesis and promotes angiogenesis

Coronary atherosclerosis complicated by plaque disruption and thrombosis is a critical event in myocardial infarction and stroke, the major causes of cardiovascular death. In atherogenesis, macrophages (MAC) and smooth muscle cells (SMC) are key actors; they synthesize matrix components and numerous factors involved in the process. Here, we design experiments to investigate whether SMC–MAC communication induces changes in ECM protein composition and/or neo-angiogenesis. Cell to cell communication was achieved using trans-well chambers, where SMCs were grown in the upper chamber and differentiated MAC in the bottom chamber for 24 or 72h. We found that cross-talk between MAC and SMC during co-culture: (i) significantly decreased the expression of ECM proteins (collagen I, III, elastin) in SMC; (ii) increased the expression and activity of metalloprotease MMP-9 and expression of collagenase MMP-1, in both MAC and SMC; (iii) augmented the secretion of soluble VEGF in the conditioned media of cell co-culture and VEGF gene expression in both cell types, compared with control cells. Moreover, the conditioned media collected from MAC–SMC co-culture promoted endothelial cell tube formation in Matrigel, signifying an increased angiogenic effect. In addition, the MAC–SMC communication led to an increase in inflammatory IL-1β and TLR-2, which could be responsible for cellular signaling. In conclusion, MAC–SMC communication affects factors and molecules that could alter ECM composition and neo-angiogenesis, features that could directly dictate the progression of atheroma towards the vulnerable plaque. Targeting the MAC–SMC cross-talk may represent a novel therapeutic strategy to slow-down or retard the plaque progression.

Single-Step Synthesis of Heparin-Doped Polypyrrole Nanoparticles for Delivery of Angiogenic Factor

To perform one-pot synthesis of heparin-immobilized polypyrrole (PPy) nanoparticles and evaluate the use of these nanoparticles for the delivery of VEGF. Heparin-stabilized synthesis of PPy nanoparticles was performed via oxidative polymerization. VEGF-bound PPy-heparin nanoparticles were delivered to endothelial cells and bioactivity of VEGF was assessed by Matrigel tube formation. Size-controllable synthesis of heparin-doped PPy nanoparticles was achieved, and heparin promoted the conjugation of VEGF. Angiogenic activity of the VEGF-conjugated PPy nanoparticles was verified. Heparin-doped PPy nanoparticles can be synthesized using one-pot reaction and provide a delivery platform by which VEGF can be conjugated onto.

Upregulation of miR-483-3p contributes to endothelial progenitor cells dysfunction in deep vein thrombosis patients via SRF.

BackgroundEndothelial progenitor cells (EPCs) contribute to recanalization of deep vein thrombosis (DVT). This study aimed to detect miRNA expression profiles in EPCs from patients with DVT and characterize the role of miRNA in EPCs dysfunction.MethodsEPCs was isolated from DVT patients and control subjects, and miRNA expression profiles were compared to screen differential miRNAs. The candidate miRNAs were confirmed by RT-PCR analysis. The targets of miRNA were identified by bioinformatics analyses, luciferase reporter assay and gene expression analyses. The apoptosis, migration and tube formation of EPCs were examined by flow cytometry, transwell assay and matrigel tube formation assay. A rat model of venous thrombosis was established as in vivo model.ResultsWe identified miR-483-3p as a candidate miRNA upregulated in EPCs from DVT patients. By using miR-483-3p agomir and antagomir, we demonstrated that miR-483-3p decreased the migration and tube formation while increased the apoptosis of EPCs. Moreover, we identified serum response factor (SRF) as the target of miR-483-3p, and showed that SRF knockdown decreased the migration and tube formation while increased the apoptosis of EPCs. In addition, miR-483-3p inhibition led to enhanced ability of homing and thrombus resolution of EPCs in rat model of venous thrombosis.ConclusionsmiR-483-3p is upregulated in EPCs from DVT patients, and it targets SRF to decrease EPCs migration and tube formation and increase apoptosis in vitro, while decrease EPCs homing and thrombus resolution in vivo. MiR-483-3p is a potential therapeutic target in DVT treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-016-0775-2) contains supplementary material, which is available to authorized users.

Effect of schisantherin A inhibit liver sinusoid endothelial cell function and action against liver fibrosis relating to angiogenesis

To investigate the effect of schisantherin A on liver sinusoid endothelial cell function and angiogenesis. Different dosages (0-40 μmol•L⁻¹) of schisantherin A were incubated 24 h with SK-HEP-1 cells, and the toxicity of SK-HEP-1 cells was assayed by MTT method. The proliferation of SK-HEP-1 cells were induced by the vascular endothelial growth factor (VEGF), with receptor tyrosine kinase inhibitor sorafenib as the control, at the same time, set up the control group, 2, 20 μmol•L⁻¹ schisantherin A were incubated with SK-HEP-1 cells, cell proliferation was analyzed by EdU DNA cell proliferation kit. Fluorescence probe method was used to assay the intracellular NO levels and NOS activity. Tube formation was observed using cell migration and a matrigel tube formation assay. Rat aortic ring assay was performed to observe the sprouting vessels from aortic ring. The fluorescence vessels, the number of functional blood vessels, and intersegmental vessel changes of transgenic zebrafish were also observed. Compared with control group, the proliferation of SK-HEP-1 cells induced by VEGF increased and and the level of NO and NOS activity induced; compared with model group, 2, 20 μmol•L⁻¹ schisantherin A and sorafenib inhibited the proliferation of SK-Hep-1 cells induced by VEGF, and reduced the level of NO and NOS activity. At the dosage of 20 μmol•L⁻¹, schisantherin A attenuated the migration and tube formation of SK-HEP-1 cells induced by VEGF, and also inhibition the formation of rat aortic rings and intersegmental vessel changes of transgenic zebrafish, and significantly reduce the number of vessels in zebrafish. Schisantherin A has potential effects on function of endothelial cell proliferation and angiogenesis.

In vitro and in vivo evaluation of FGF2 and FGF9 dual-loaded poly(ester amide) fibers for therapeutic angiogenesis

Event Abstract Back to Event In vitro and in vivo evaluation of FGF2 and FGF9 dual-loaded poly(ester amide) fibers for therapeutic angiogenesis Somiraa Said1, Caroline O’neil2, Hao Yin2, Zengxuan Nong2, Mai Elfarnawany1, 2, Hon Leong3, James Lacefield1, 4, 5, Geoffrey Pickering2, 5, 6, 7 and Kibret Mequanint1, 8 1 The University of Western Ontario, Biomedical Engineering Graduate Program, Canada 2 The University of Western Ontario, Robarts Research Institute, Canada 3 The University of Western Ontario, Department of Surgery (Urology), Canada 4 The University of Western Ontario, Department of Electrical and Computer Engineering, Canada 5 The University of Western Ontario, Department of Medical Biophysics, Canada 6 The University of Western Ontario, Department of Biochemistry, Canada 7 The University of Western Ontario, Department of Medicine (Cardiology), Canada 8 The University of Western Ontario, Department of Chemical and Biochemical Engineering, Canada Introduction: In therapeutic angiogenesis, the delivery of angiogenic factors either by bolus injection or infusion results in their rapid clearance from the site of interest due to their short biological half-life[1]. The angiogenesis process is complex, therefore therapeutic angiogenesis regimens should include the administration of multiple growth factors and recapitulate temporal presentation of these growth factors[2],[3]. In this study, we are reporting controlled delivery of a different ‘cocktail’ of growth factors; an angiogenic factor − fibroblast growth factor-2 (FGF2) and an arteriogenic factor − fibroblast growth factor-9 (FGF9). We are aiming to achieve sustained and differential release of these two growth factors from biodegradable poly(ester amide) (PEA) electrospun fibers towards targeting neovascular formation and stabilization. Materials and Methods: FGF2 and FGF9 were dual loaded into PEA fibers using a mixed blend and emulsion electrospinning technique. In vitro release kinetics of FGF2/FGF9 dual-loaded PEA fibers was studied in PBS (pH 7.4) at 37 ºC for 28 days using ELISA as previously described[4]. In vitro angiogenesis assays including Matrigel tube formation assay and Boyden chamber transwell assay were used to evaluate endothelial cell (EC) tube formation, directed smooth muscle cell (SMC) migration, and EC-SMC interaction. Ex ovo chick chorioallantoic membrane (CAM) model coupled with power Doppler ultrasound imaging was employed to assess the in vivo angiogenic capacity of our delivery system. Results and Discussion: In vitro release studies showed controlled and differential release of both factors in a bioactive form. Co-released FGF2 and FGF9 from dual loaded PEA fibers enhanced EC tube formation, directed-migration of SMCs towards PDGF-BB, and EC/SMC tube stabilization. The CAM assay showed a higher percentage increase in vascular density of the full CAM surface treated with FGF2/FGF9 dual-loaded fibers with time (Figure 1). Power Doppler 3D volumes showed the formation of smaller vessels near the CAM surface in the case of dual-loaded PEA fibers and soluble growth factors treated CAMs that were not observed in the case of unloaded PEA fibers treated CAMs and the negative control, which may indicate a localized angiogenic effect (Figure 2). Conclusion: Localized angiogenesis was observed at the interface between the dual-loaded fibrous mat and the CAM surface. The CAM model had some limitations in detecting a statistically significant difference in the full CAM vasculature due to its rapid vascular growth that did not emulate the controlled and relatively slow release of FGF2 and FGF9 from the PEA fibers. Despite the aforementioned limitations, the in vitro angiogenesis assays data together with the preliminary CAM assay data suggests that FGF2/FGF9 dual loaded PEA fibers can have a potential therapeutic angiogenesis application for treatment of ischemic vascular diseases. Moving forward, a more clinically relevant model, the ischemic hind limb mouse model will be employed to better investigate the angiogenic effects of the FGF2/FGF9 dual-loaded PEA fibers. The Authors acknowledge the financial support from The Heart and Stroke Foundation of Canada, the Canadian Institutes for Health Research (FRN 11715), the Canadian Cancer Society (Grant #701080), and the Natural Sciences and Engineering Research Council of Canada.

Early outgrowth cells versus endothelial colony forming cells functions in platelet aggregation.

BackgroundEndothelial progenitor cells (EPCs) have been implicated in neoangiogenesis, endothelial repair and cell-based therapies for cardiovascular diseases. We have previously shown that the recruitment of EPCs to sites of vascular lesions is facilitated by platelets where EPCs, in turn, modulate platelet function and thrombosis. However, EPCs encompass a heterogeneous population of progenitor cells that may exert different effects on platelet function. Recent evidence suggests the existence of two EPC subtypes: early outgrowth cells (EOCs) and endothelial colony-forming cells (ECFCs). We aimed at characterizing these two EPC subtypes and at identifying their role in platelet aggregation.MethodsEOCs and ECFCs were generated from human peripheral blood mononuclear cells (PBMCs) seeded in conditioned media on fibronectin and collagen, respectively. The morphological, phenotypical and functional characteristics of EOCs and ECFCs were assessed by optical and confocal laser scanning microscopes, cell surface markers expression, and Matrigel tube formation. The impact of EOCs and ECFCs on platelet aggregation was monitored in collagen-induced optical aggregometry and compared with PBMCs and human umbilical vein endothelial cells (HUVECs). The levels of the anti-platelet agents’ nitric oxide (NO) and prostacyclin (PGI2) released from cultured cells as well as the expression of their respective producing enzymes NO synthases (NOS) and cyclooxygenases (COX) were also assessed.ResultsWe showed that EOCs display a monocytic-like phenotype whereas ECFCs have an endothelial-like phenotype. We demonstrated that both EOCs and ECFCs and their supernatants inhibited platelet aggregation; however ECFCs were more efficient than EOCs. This could be related to the release of significantly higher amounts of NO and PGI2 from ECFCs, in comparison to EOCs. Indeed, ECFCs, like HUVECs, constitutively express the endothelial (eNOS)—and inducible (iNOS)—NOS isoforms, and COX-1 and weakly express COX-2, whereas EOCs do not constitutively express these NO and PGI2 producing enzymes.ConclusionThe different morphological, phenotypic and more importantly the release of the anti-aggregating agents PGI2 and NO in each EPC subtype are implicated in their respective roles in platelet function and thus, may be linked to the increased efficiency of ECFCs in inhibiting platelet aggregation as compared to EOCs.