Inhibition of angiogenic initiation and disruption of newly established human vascular networks by juice from Morinda citrifolia (noni)

noni, the juice of the fruit from the Morinda citrifolia plant, has been used for centuries as a medicinal agent. We tested the effects of noni juice in a three-dimensional fibrin clot matrix model using human placental vein and human breast tumor explants as sources for angiogenic vessel development. Noni in concentrations of 5% (vol/vol) or greater was highly effective in inhibiting the initiation of new vessel sprouts from placental vein explants, compared with initiation in control explants in media supplemented with an equivalent amount of saline. These concentrations of noni were also effective in reducing the growth rate and proliferation of newly developing capillary sprouts. When used at a concentration of 10% in growth media, noni was able to induce vessel degeneration and apoptosis in wells with established capillary networks within a few days of its application. We also found that 10% noni juice in media was an effective inhibitor of capillary initiation in explants from human breast tumors. In tumor explants which did show capillary sprouting, the vessels rapidly degenerated (2-3 days) in those exposed to media supplemented with 10% noni.     

Induction of membrane-type matrix metalloproteinase-1 stimulates angiogenic activities of bovine aortic endothelial cells

Matrix metalloproteinases (MMPs) have been reported to play critical roles in endothelial cell migration and matrix remodeling during the angiogenic process. Among these MMPs, membrane-type MMP-1 (MT1-MMP) is an important molecule that can trigger the invasion of tumor cells by activating MMP-2 on their plasma membrane. However, the precise involvement of MT1-MMP in the angiogenic process has not been determined. To investigate the roles of the MT1-MMP by the matrix remodeling of endothelial cells, MT1-MMP expression vector was transfected into bovine aortic endothelial cells (BAECs). Increased expression of MT1-MMP in BAECs enhanced the activation of MMP-2, invasion and migration of BAECs. Moreover, the capacity of tube formation was increased in MT1-MMP transfectants. However, cotransfection with antisense MT1-MMP expression vector abolished the effects of MT1-MMP overexpression. These observations indicate that MT1-MMP is involved in the angiogenic process of endothelial cells in vitro. This revised version was published online in June 2006 with corrections to the Cover Date.     

Variations in mechanical stiffness alter microvascular sprouting and stability in a PEG hydrogel model of idiopathic pulmonary fibrosis

Objective

Microvascular remodeling is governed by biomechanical and biochemical cues which are dysregulated in idiopathic pulmonary fibrosis. Understanding how these cues impact endothelial cell-pericyte interactions necessitates a model system in which both variables can be independently and reproducibly modulated. In this study we develop a tunable hydrogel-based angiogenesis assay to study how varying angiogenic growth factors and environmental stiffness affect sprouting and vessel organization.

Methods

Lungs harvested from mice were cut into 1 mm long segments then cultured on hydrogels having one of seven possible stiffness and growth factor combinations. Time course, brightfield, and immunofluorescence imaging were used to observe and quantify sprout formation.

Results

Our assay was able to support angiogenesis in a comparable manner to Matrigel in soft 2 kPa gels while enabling tunability to study the effects of stiffness on sprout formation. Matrigel and 2 kPa groups contained significantly more samples with sprouts when compared to the stiffer 10 and 20 kPa gels. Growth factor treatment did not have as obvious an effect, although the 20 kPa PDGF + FGF-treated group had significantly longer vessels than the vascular endothelial growth factor-treated group.

Conclusions

We have developed a novel, tunable hydrogel assay for the creation of lung explant vessel organoids which can be modulated to study the impact of specific environmental cues on vessel formation and maturation.     

Skeletal myoblast based delivery of angiogenic growth factors: a comparison between angiopoietin-1 and VEGF gene delivery for therapeutic angiogenesis in the heart

Introduction Extensive cell death and an associated myocardial dys- function are the common features of chronic heart disease. Given the inadequate ability of the human heart to regenerate, a more recent approach to counter the remodel- ing process is to compensate for the loss of functioning cardiomyocyte number through stem cell transplantation with angiomyogenic potential.1,2 The novel approach of heart cell therapy is to repopulate the scar tissue with myogenic cells that may be functional…     

Effects of angiogenic regulators on in vitro proliferation and cytokine secretion by native human acute myelogenous leukemia blasts

Angiogenesis seems to be important in the pathogenesis of acute myelogenous leukemia (AML). The endothelial cell proliferation and microvessel formation are regulated by a wide range of soluble mediators, including angiogenin, angiopoietin-2, basic fibroblast growth factors, vascular endothelial growth factor (VEGF), VEGF-D, angiostatin and endostatin. In the present study, it has been investigated whether these mediators have an additional direct effect on the proliferation and cytokine release by native human AML blasts. AML cells derived from a large group of consecutive patients were investigated. All these mediators could alter the proliferation and cytokine release [interleukin (IL) 1beta, IL6, IL8, tumor necrosis factor alpha] for a minority of patients. Alteration of spontaneous proliferation by at least one mediator was detected in five of 38 patients; whereas, altered cytokine (Flt3-ligand, granulocyte-macrophage colony-stimulating factor, stem cell factor)-dependant proliferation was observed for 10 patients. Growth enhancement was most frequently observed, whereas growth inhibition was uncommon. The effects on AML blast proliferation were often dependant on or were modulated by the presence of the three hematopoietic growth factors. Based on the present results, it is concluded that angioregulatory mediators have additional growth-enhancing effects directly on the AML blasts for certain patients. However, based on the results from this investigation and previous studies it is suggested that their major contribution to the pathogenesis of AML is through their effects on regulation of bone marrow angiogenesis, and future studies of these mediators in AML should probably focus on these effects.     

Differentiation and expansion of endothelial cells from human bone marrow CD133+ cells

We report a method of purifying, characterizing and expanding endothelial cells (ECs) derived from CD133(+) bone marrow cells, a subset of CD34(+) haematopoietic progenitors. Isolated using immunomagnetic sorting (mean purity 90 +/- 5%), the CD133(+) bone marrow cells were grown on fibronectin-coated flasks in M199 medium supplemented with fetal bovine serum (FBS), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and insulin growth factor (IGF-1). The CD133(+) fraction contained 95 +/- 4% CD34(+) cells, 3 +/- 2% cells expressing VEGF receptor (VEGFR-2/KDR), but did not express von Willebrand factor (VWF), VE-cadherin, P1H12 or TE-7. After 3 weeks of culture, the cells formed a monolayer with a typical EC morphology and expanded 11 +/- 5 times. The cells were further purified using Ulex europaeus agglutinin-1 (UEA-1)-fluorescein isothiocyanate (FITC) and anti-FITC microbeads, and expanded with VEGF for a further 3 weeks. All of the cells were CD45(-) and CD14(-), and expressed several endothelial markers (UEA-1, VWF, P1H12, CD105, E-selectin, VCAM-1 and VE-cadherin) and typical Weibel-Palade bodies. They had a high proliferative potential (up to a 2400-fold increase in cell number after 3 weeks of culture) and the capacity to modulate cell surface antigens upon stimulation with inflammatory cytokines. Purified ECs were also co-cultivated with CD34(+) cells, in parallel with a purified fibroblastic cell monolayer. CD34(+) cells (10 x 10(5)) gave rise to 17,951 +/- 2422 CFU-GM colonies when grown on endothelial cells, and to 12,928 +/- 4415 CFU-GM colonies on fibroblast monolayers. The ECs also supported erythroid blast-forming unit (BFU-E) colonies better. These results suggest that bone marrow CD133(+) progenitor cells can give rise to highly purified ECs, which have a high proliferative capacity, can be activated by inflammatory cytokines and are superior to fibroblasts in supporting haematopoiesis. Our data support the hypothesis that endothelial cell progenitors are present in adult bone marrow and may contribute to neo-angiogenesis.     

The role of miRNA in stem cell pluripotency and commitment to the vascular endothelial lineage

Vascular endothelial cells derived from human pluripotent stem cells have substantial potential for the development of novel vascular therapeutics and cell-based therapies for the repair of ischemic damage. To gain maximum benefit from this source of cells, a complete understanding of the changes in gene expression and how they are regulated is required. miRNAs have been demonstrated to play a critical role in controlling stem cell pluripotency and differentiation and are important for mature endothelial cell function. Specific miRNAs that determine stem cell fate have been identified for a number of different cell lineages; however, in the case of differentiation and specification of vascular endothelial cells, this is yet to be fully elucidated.     

Hypoxia triggers a proangiogenic pathway involving cancer cell microvesicles and PAR-2-mediated heparin-binding EGF signaling in endothelial cells

Highly malignant tumors, such as glioblastomas, are characterized by hypoxia, endothelial cell (EC) hyperplasia, and hypercoagulation. However, how these phenomena of the tumor microenvironment may be linked at the molecular level during tumor development remains ill-defined. Here, we provide evidence that hypoxia up-regulates protease-activated receptor 2 (PAR-2), i.e., a G-protein-coupled receptor of coagulation-dependent signaling, in ECs. Hypoxic induction of PAR-2 was found to elicit an angiogenic EC phenotype and to specifically up-regulate heparin-binding EGF-like growth factor (HB-EGF). Inhibition of HB-EGF by antibody neutralization or heparin treatment efficiently counteracted PAR-2-mediated activation of hypoxic ECs. We show that PAR-2-dependent HB-EGF induction was associated with increased phosphorylation of ERK1/2, and inhibition of ERK1/2 phosphorylation attenuated PAR-2-dependent HB-EGF induction as well as EC activation. Tissue factor (TF), i.e., the major initiator of coagulation-dependent PAR signaling, was substantially induced by hypoxia in several types of cancer cells, including glioblastoma; however, TF was undetectable in ECs even at prolonged hypoxia, which precludes cell-autonomous PAR-2 activation through TF. Interestingly, hypoxic cancer cells were shown to release substantial amounts of TF that was mainly associated with secreted microvesicles with exosome-like characteristics. Vesicles derived from glioblastoma cells were found to trigger TF/VIIa-dependent activation of hypoxic ECs in a paracrine manner. We provide evidence of a hypoxia-induced signaling axis that links coagulation activation in cancer cells to PAR-2-mediated activation of ECs. The identified pathway may constitute an interesting target for the development of additional strategies to treat aggressive brain tumors.     

Serum levels of angiogenic factors indicate a pro-angiogenic state in adults with sickle cell disease

Hypoxia-induced angiogenesis may play an important role in the pathophysiology of sickle cell disease (SCD). Serum levels of angiopoietin (Ang)-1, Ang-2, vascular endothelial growth factor, placenta growth factor (PlGF), soluble tunica intima endothelial kinase 2 (sTIE2), erythropoietin (EPO) and endothelial activation markers (soluble vascular adhesion molecule-1, soluble intercellular adhesion molecule-1) were determined in controls, HbSS (n = 35) and HbSC (n = 23) patients. In the asymptomatic phase, serum Ang-2 (P < 0.001), EPO (P < 0.001) and sTIE2 (P = 0.03) were elevated in patients. During painful crises, increased Ang-2 (P < 0.001) and PlGF (P = 0.04) occurred in HbSS and Ang-2 (P = 0.05) in HbSC patients. These results indicate a pro-angiogenic state in SCD, mainly because of elevated Ang-2 levels.     

Cyclic AMP concentrations in dendritic cells induce and regulate Th2 immunity and allergic asthma

The inductive role of dendritic cells (DC) in Th2 differentiation has not been fully defined. We addressed this gap in knowledge by focusing on signaling events mediated by the heterotrimeric GTP binding proteins Gαs, and Gαi, which respectively stimulate and inhibit the activation of adenylyl cyclases and the synthesis of cAMP. We show here that deletion of Gnas, the gene that encodes Gαs in mouse CD11c⁺ cells (Gnas^ΔCD11c mice), and the accompanying decrease in cAMP provoke Th2 polarization and yields a prominent allergic phenotype, whereas increases in cAMP inhibit these responses. The effects of cAMP on DC can be demonstrated in vitro and in vivo and are mediated via PKA. Certain gene products made by Gnas^ΔCD11c DC affect the Th2 bias. These findings imply that G protein-coupled receptors, the physiological regulators of Gαs and Gαi activation and cAMP formation, act via PKA to regulate Th bias in DC and in turn, Th2-mediated immunopathologies.The induction of Th cell response requires antigen-presenting cells (APC), especially dendritic cells (DC), but the mechanisms for this induction have not been fully elucidated (1, 2). Because DC do not produce IL-4, which is mandatory for GATA3 induction and Th2 cell differentiation (3, 4), other cell types may be involved in Th2 responses (1, 5, 6), including basophils (7), epithelial cells (8), and innate lymphoid cells (ILC), especially ILC group 2 (ILC2) (9). ILCs are a multifunctional group of cells that are able to secrete immunoregulatory cytokines that affect immune responses. They reside at mucosal surfaces, where they are exposed to microbial or environmental stimulation (10). Such cells can secrete IL-4 or alarmins, including IL-25, IL-33, and TSLP (epithelial cells), which support Th2 differentiation (11). Other DC-derived inducers of Th2-differentiation are the Notch ligand Jagged 1 (12) and the interaction between OX40 and OX40L (13). However, little is known regarding the signaling networks that provoke DC to induce Th2 immunity.Pharmacological inhibition of cyclic nucleotide phosphodiesterase 4 (PDE4), which is highly expressed in DC, can produce improvement in animal models of inflammation and autoimmunity and can suppress human Th1-polarizing capacity by increasing cAMP concentrations (14, 15). Based on these findings and our previous work that identified a role for cAMP in DC in Th17 induction (16), we hypothesized that cAMP regulates DC and affects Th differentiation bias. To test this hypothesis, we studied the regulation of DC activity by heterotrimeric (αβγ) GTP binding proteins that regulate cAMP synthesis through their modulation of the activity of adenylyl cyclases (ACs): Gαs, which stimulates AC activity, and Gαi, which inhibits membrane AC activity.In the current studies, we engineered mice that have a CD11c-specific deletion of Gnas (CD11c-Cre Gnas^fl/fl, i.e., Gnas^ΔCD11c), the gene that encodes Gαs (17). We found that cAMP accumulation is much less in response to Gαs activation of CD11c⁺ cells from these mice than from littermate (fl/fl) controls. Unexpectedly, the Gnas^ΔCD11c mice display a striking phenotype: They develop spontaneous Th2 immunity even though these mice have a C57BL/6 genetic background, which is biased to Th1 immunity (18). Consequently, these mice develop later airway inflammation that is consistent with allergic asthma (19). Bone marrow (BM)-derived DC (BMDC) from the Gnas^ΔCD11c mice display a pro-Th2 phenotype (i.e., induce a Th2 response when cocultured with CD4 T cells), which can be prevented by treatment with a cAMP analog. Additional studies show that the cAMP effector protein kinase A (PKA) and molecules whose expression is regulated by cAMP play a key role in the induction of the Th2-biased phenotype of DC. The current results thus identify a previously unappreciated role for Gαs-regulated cAMP synthesis and cAMP/PKA in DC in determining Th subset differentiation and resultant responses.     

TNP-470 and recombinant human interferon-alpha2a inhibit angiogenesis synergistically

The hypothesis that the combination of two known antiangiogenic agents TNP-470 and interferon (IFN)-alpha exerts synergistic effects has been investigated in vitro and in vivo. In vitro, TNP-470 and recombinant human IFN-alpha2a (rhIFN-alpha2a) resulted in a dose-dependent inhibition of proliferation of human umbilical vein endothelial cells (HUVECs) and EA.hy926 endothelial cells. Compared with the two agents used singly at their lowest or ineffective doses, combined treatment with the same doses inhibited more intensely in the absence of cytotoxicity and displayed similar behaviour on cell chemotaxis and capillary morphogenesis on Matrigel. However, the secretion of matrix metalloproteinase 2 (MMP-2) and MMP-9 was not influenced by the two agents, either alone or in combination, even when they were applied at their lowest efficacious doses or at higher cytotoxic doses. Experiments in vivo with the chick embryo chorioallantoic membrane (CAM)-sponge assay revealed the same dose-dependent inhibition and synergy. As the basic fibroblast growth factor (bFGF)-induced angiogenesis in the CAM-sponge model was strongly inhibited by the combined treatment, TNP-470 and rhIFN-alpha2a would appear to exert antiangiogenesis synergistically, perhaps by interfering with the bFGF-mediated pathway.     

Soluble VEGFR-1 secreted by endothelial cells and monocytes is present in human serum and plasma from healthy donors

It was shown before that the soluble form of VEGFR-1 (sVEGFR-1) is present in serum of pregnant women. The aim of the present study was to investigate the presence of this endogenous vascular endothelial growth factor-A (VEGF-A) antagonist in human serum in more detail. sVEGFR-1 was detected in human serum and plasma from normal healthy male and female donors by ELISA. sVEGFR-1 levels ranged from non-detectable up to 440 pg/ml, with no significant difference between male and female donors. In addition, vein endothelial cells (ECs) from an intact vascular bed, the umbilical cord, were shown to secrete sVEGFR-1. Furthermore, human peripheral blood monocytes, a non-EC type expressing VEGFR-1, were shown to contribute to the sVEGFR-1 detectable in human serum and plasma for the first time. EC- and monocyte-derived sVEGFR-1 proved capable of inhibiting the VEGF-induced proliferation and migration of ECs in vitro. Finally, secretion of sVEGFR-1 was increased by the angiogenic factor basic fibroblast growth factor (bFGF) in human ECs and was also enhanced in lipopolysaccharide-activated human monocytes. In human umbilical vein endothelial cells, both the membrane-bound and the sVEGFR-1 seem to be equally regulated on the mRNA as well as the protein level. The presence of an sVEGFR-1 in human serum and plasma of normal male and female donors strongly suggests that it plays an important role as a naturally occurring VEGF antagonist in the regulation and availability of VEGF-mediated biological activities in vivo. This revised version was published online in June 2006 with corrections to the Cover Date.     

ERK1/2信号通路在内皮微粒诱导人脐静脉内皮细胞ICAM-1表达中的作用

目的:探讨细胞外信号调节激酶1/2（ERK1/2）信号通路在内皮微粒（EMPs）诱导人脐静脉内皮细胞（HUVECs）表达细胞间黏附分子-1（ICAM-1）中的作用。方法:体外培养HUVECs,选取生长良好的第4～5代细胞,分为EMPs不同浓度作用组、EMPs不同时间作用组及ERKl/2特异性抑制剂组。应用蛋白免疫印迹法（Western blot）检测ICAM-1和磷酸化ERK1/2蛋白的表达。用实时荧光定量PCR（qRT-PCR）检测ICAM-1 mRNA的表达。结果:EMPs作用HUVECs后,ICAM-1 mRNA和其蛋白以及磷酸化ERK1/2蛋白的表达显著高于对照组,且呈浓度和时间依赖性的关系（均P<0.01）;而ERKl/2特异性抑制剂PD98059对ICAM-1 mRNA和其蛋白以及磷酸化ERK1/2蛋白的表达,均有明显的抑制作用（均P<0.01）。结论:EMPs可诱导HUVECs中ICAM-1表达,其机制可能与激活ERK1/2信号通路有关。     

缺氧对血管内皮细胞内Ca2+的影响以及合贝爽的保护作用

目的观察缺氧对人大血管内皮细胞内Ca2 水平的影响以及合贝爽的保护作用。方法将培养的血管内皮细胞分为对照组、缺氧组和治疗组(加入合贝爽再缺氧),应用激光共聚焦显微镜测量各组内皮细胞内Ca2 水平。结果与对照组及治疗组比较,缺氧组细胞内Ca2 水平显著升高(P<0.01),治疗组与对照组比较无统计学差异(P>0.05)。结论缺氧可引起血管内皮细胞内钙超载,合贝爽对其具有保护作用。     

重组人血管内皮抑制素对多发性骨髓瘤内皮细胞增殖和迁移的影响

目的观察重组人血管内皮抑制素注射液(内皮抑素)对人脐静脉内皮细胞株(HUVEC)和多发性骨髓瘤细胞株KM3抑制增殖及诱导凋亡的作用,研究其对KM3细胞培养上清诱导的HUVEC迁移效果的影响。方法 WST-1法观察不同浓度的内皮抑素分别对HUVEC和KM3细胞株的增殖抑制作用,Annexin V-FITC法检测有效浓度的内皮抑素对HUVEC和KM3细胞株的凋亡作用,改良的Boyden小室法检测内皮抑素对KM3细胞株培养上清诱导的HUVEC迁移的影响。结果 50～500 ng/mL内皮抑素对HUVEC具有抑制增殖作用,而对KM3细胞未见明显作用。100、200 ng/mL的内皮抑素对HUVEC具有诱导凋亡作用;而对KM3细胞未见明显作用。与不加药组相比,内皮抑素能抑制KM3细胞培养上清促内皮细胞迁移的作用(P<0.01)。结论内皮抑素能抑制HUVEC的增殖及诱导其凋亡,并能抑制骨髓瘤细胞的促内皮细胞迁移作用。