Disproportion in Pericyte/Endothelial Cell Proliferation and Mechanisms of Intussusceptive Angiogenesis Participate in Bizarre Vessel Formation in Glioblastoma

Glioblastoma (GBM) is the most malignant tumor in the brain. In addition to the vascular pattern with thin-walled vessels and findings of sprouting angiogenesis, GBM presents a bizarre microvasculature (BM) formed by vascular clusters, vascular garlands, and glomeruloid bodies. The mechanisms in BM morphogenesis are not well known. Our objective was to assess the role of pericyte/endothelial proliferation and intussusceptive angiogenic mechanisms in the formation of the BM. For this purpose, we studied specimens of 66 GBM cases using immunochemistry and confocal microscopy. In the BM, the results showed (a) transitional forms between the BM patterns, mostly with prominent pericytes covering all the abluminal endothelial cell (EC) surface of the vessels, (b) a proliferation index high in the prominent pericytes and low in ECs (47.85 times higher in pericytes than in ECs), (c) intravascular pillars (hallmark of intussusceptive angiogenesis) formed by transcapillary interendothelial bridges, endothelial contacts of opposite vessel walls, and vessel loops, and (d) the persistence of these findings in complex glomeruloid bodies. In conclusion, disproportion in pericyte/EC proliferation and mechanisms of intussusceptive angiogenesis participate in BM formation. The contributions have morphogenic and clinical interest since pericytes and intussusceptive angiogenesis can condition antiangiogenic therapy in GBM.

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Abstract P248: Novel Role of Axl Kinase in Endothelial Cell Proliferation and Pulmonary Arterial Hypertension

Hypertension ◽

10.1161/hyp.70.suppl_1.p248 ◽

2017 ◽

Vol 70 (suppl_1) ◽

Author(s):

Anastasia Gorelova ◽

Sanghamitra Sahoo ◽

Patrick J Pagano

Keyword(s):

Cell Proliferation ◽

Endothelial Cell ◽

Pulmonary Arterial Hypertension ◽

Arterial Hypertension ◽

Endothelial Cell Proliferation ◽

Vegf Receptor ◽

Drug Bioavailability ◽

Endothelial Proliferation ◽

Pulmonary Arterial

Pulmonary arterial hypertension (PAH) is a poorly characterized disease of unclear etiology that affects individuals of all ages. Vascular remodeling and increase in pulmonary artery (PA) and right ventricle (RV) pressures are two major culprits in RV failure and death in PAH. Recent advances in the study of PAH suggest that endothelial cell proliferation is an early instigator of this hallmark remodeling. We postulated that Axl receptor tyrosine kinase (implicated in pro-proliferative and pro-survival signaling in cancerous cells) could mediate endothelial proliferation and thus hemodynamic changes occurring in PAH. Using immunofluorescent microscopy of lung microvessels of human PAH vs. non-PAH, we observed Axl expression on intimal endothelial cells but not medial smooth muscle cells. Furthermore, digitized microscopy revealed that Axl tended to increase on the endothelium of PAH vessels (1.65±0.15-fold vs. non-PAH; n=3-4; p=0.057 ). To address the role of Axl in vivo , an Axl inhibitor R428 was employed in a mouse model of pulmonary hypertension. C57Bl/6 mice were subjected to hypoxia at pO 2 =10% and VEGF receptor antagonist SU5416 (Su/Ch) or normoxia (Norm) for 3 wks. Indeed, Su/Ch caused a significant rise in lung Axl protein and mRNA (7.1±0.4- and 2.4±0.5-fold, Su/Ch vs. Norm, protein and mRNA, respectively; n=3-6; p<0.01). As predicted, RV pressure (RVP) rose from 27±0.5 to 43±1.8 mmHg (Norm vs. Su/Ch; n=6; p<0.01). However, we did not observe a decrease in RVP with twice-daily gavage of 75 mg/kg R428 (43±1.4 mmHg, Su/Ch + R428; n=6). A similar pattern was observed with mean PA pressure (18.4±0.3 and 28.7±1.2 mmHg, Norm vs. Su/Ch, p<0.01; 28.7±0.9 mmHg, Su/Ch + R428), RV resistance (1403±256 vs. 2703±464 Wood units, Norm vs. Su/Ch, n/s; vs. 3610±625 Wood units, Su/Ch + R428) and Fulton index (0.26±0.01 and 0.34±0.02, Norm vs. Su/Ch, p<0.05; 0.38±0.02, Su/Ch + R428). In conclusion, our preliminary results demonstrate upregulated Axl expression in the endothelium of PAH patients and in lungs of PH mice and suggest that Axl kinase may play a novel role in pulmonary vascular endothelial proliferation and remodeling in PAH. It remains to be determined whether drug bioavailability or severity of disease precluded an ameliorative effect of an Axl inhibitor.

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Resistance Mechanisms of Anti-angiogenic Therapy and Exosomes-Mediated Revascularization in Cancer

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2020.610661 ◽

2020 ◽

Vol 8 ◽

Author(s):

Ye Zeng ◽

Bingmei M. Fu

Keyword(s):

Vasculogenic Mimicry ◽

Resistance Mechanisms ◽

Vascular Endothelial ◽

Beneficial Effects ◽

Sprouting Angiogenesis ◽

Intussusceptive Angiogenesis ◽

Angiogenic Therapy ◽

Tumor Neovascularization ◽

Endothelial Growth Factor

Anti-angiogenic therapies (AATs) have been widely used for cancer treatment. But the beneficial effects of AATs are short, because AAT-induced tumor revascularization facilitates the tumor relapse. In this mini-review, we described different forms of tumor neovascularization and revascularization including sprouting angiogenesis, vessel co-option, intussusceptive angiogenesis, and vasculogenic mimicry, all of which are closely mediated by vascular endothelial growth factor (VEGF), angiopoietins, matrix metalloproteinases, and exosomes. We also summarized the current findings for the resistance mechanisms of AATs including enhancement in pro-angiogenic cytokines, heterogeneity in tumor-associated endothelial cells (ECs), crosstalk between tumor cells and ECs, masking of extracellular vesicles, matrix stiffness and contributions from fibroblasts, macrophages and adipocytes in the tumor microenvironment. We highlighted the revascularization following AATs, particularly the role of exosome stimulating factors such as hypoxia and miRNA, and that of exosomal cargos such as cytokines, miRNAs, lncRNAs, and circRNAs from the tumor ECs in angiogenesis and revascularization. Finally, we proposed that renormalization of tumor ECs would be a more efficient cancer therapy than the current AATs.

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Mid-luteal angiogenesis and function in the primate is dependent on vascular endothelial growth factor

Journal of Endocrinology ◽

10.1677/joe.0.1680409 ◽

2001 ◽

Vol 168 (3) ◽

pp. 409-416 ◽

Cited By ~ 50

Author(s):

SE Dickson ◽

R Bicknell ◽

HM Fraser

Keyword(s):

Vascular Endothelial Growth Factor ◽

Endothelial Cells ◽

Endothelial Cell ◽

Growth Factor ◽

Luteal Phase ◽

Smooth Muscle Actin ◽

Proliferation Index ◽

Endothelial Cell Proliferation ◽

Vascular Endothelial ◽

Endothelial Growth Factor

Vascular endothelial growth factor (VEGF) is essential for the angiogenesis required for the formation of the corpus luteum; however, its role in ongoing luteal angiogenesis and in the maintenance of the established vascular network is unknown. The aim of this study was to determine whether VEGF inhibition could intervene in ongoing luteal angiogenesis using immunoneutralisation of VEGF starting in the mid-luteal phase. In addition, the effects on endothelial cell survival and the recruitment of periendothelial support cells were examined. Treatment with a monoclonal antibody to VEGF, or mouse gamma globulin for control animals, commenced on day 7 after ovulation and continued for 3 days. Bromodeoxyuridine (BrdU), used to label proliferating cells to obtain a proliferation index, was administered one hour before collecting ovaries from control and treated animals. Ovarian sections were stained using antibodies to BrdU, the endothelial cell marker, CD31, the pericyte marker, alpha-smooth muscle actin, and 3' end DNA fragments as a marker for apoptosis. VEGF immunoneutralisation significantly suppressed endothelial cell proliferation and the area occupied by endothelial cells while increasing pericyte coverage and the incidence of endothelial cell apoptosis. Luteal function was markedly compromised by anti-VEGF treatment as judged by a 50% reduction in plasma progesterone concentration. It is concluded that ongoing angiogenesis in the mid-luteal phase is primarily driven by VEGF, and that a proportion of endothelial cells of the mid-luteal phase vasculature are dependent on VEGF support.

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Abstract 3640: Mitochondrial Uncoupling Protein 2 Facilitates Endothelial Cell Growth and Angiogenesis via Reduction of Mitochondrial Superoxide

Circulation ◽

10.1161/circ.118.suppl_18.s_456-b ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Yukio Shimasaki ◽

Kai Chen ◽

John F Keaney

Keyword(s):

Endothelial Cells ◽

Endothelial Cell ◽

Cell Growth ◽

Mitochondrial Function ◽

Endothelial Cell Proliferation ◽

Wild Type ◽

Sprouting Angiogenesis ◽

Mitochondrial Superoxide ◽

Endothelial Cell Growth ◽

Aortic Explants

Background: Growing evidence suggests that mitochondrial function contributes to cell phenotype. One important component of mitochondrial function is the membrane potential that is controlled, in part, by uncoupling proteins (UCPs). Based on our previous data, the UCP2 is predominantly expressed in cultured endothelial cells. Therefore, we sought to examine the role of UCP2 in endothelial cell growth and angiogenesis. Methods and Results: Murine lung endothelial cells (MLECs) were isolated from UCP2-null and wild-type mice. UCP2-null cells were found less proliferative than wild-type cells (P<0.02, UCP2-null cells vs. wild-type cells, n=4). This defect of UCP2-null cells was rescued by UCP2 adenovirus transfection (19% increase, p<0.02 vs. LacZ adenovirus treated cells, n=3), and also rescued by transfection with manganese superoxide dismutase (MnSOD) adenovirus (53% increase, P<0.002 vs. LacZ adenovirus treated cells, n=3). We found a reciprocal relation such as no UCP2 expression and higher mitochondrial superoxide level in the MLECs (P<0.005, UCP2-null cells vs. wild-type cells, n=3), suggesting that mitochondrial superoxide may regulate endothelial cell growth. Then, we prepared murine aortic rings from UCP2-null and wild-type mice and embedded in rat tail collagen gel. The sprouting angiogenesis of UCP2-null explants was significantly less than wild-type explants (P<0.02, UCP2-null explants vs. wild-type explants, n=3– 4). Furthermore, MLECs from MnSOD-heterozygous mice showed less proliferation with lower expression of UCP2 protein and higher mitochondrial superoxide level compared to the MLECs from wild-type littermates (P<0.02, MnSOD-heterozygous cells vs. wild-type cells, n=4 – 8). We also observed less sprouting angiogenesis in MnSOD-heterozygous aortic explants than wild-type aortic explants (P<0.05, MnSOD-heterozygous explants vs. wild-type explants, n=3– 6). Conclusions: These data indicate that mitochondrial superoxide controls endothelial cell proliferation and angiogenesis, suggesting that mitochondrial metabolism modulates the endothelial cell growth and angiogenesis.

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What makes vessels grow with exercise training?

Journal of Applied Physiology ◽

10.1152/japplphysiol.00035.2004 ◽

2004 ◽

Vol 97 (3) ◽

pp. 1119-1128 ◽

Cited By ~ 283

Author(s):

Barry M. Prior ◽

H. T. Yang ◽

Ronald L. Terjung

Keyword(s):

Vascular Remodeling ◽

Tube Formation ◽

Muscle Contractions ◽

Endothelial Cell Proliferation ◽

Mechanical Stimuli ◽

Sprouting Angiogenesis ◽

Intussusceptive Angiogenesis ◽

Powerful Stimulus ◽

Potent Growth ◽

Tissue Reorganization

Exercise and muscle contractions create a powerful stimulus for structural remodeling of the vasculature. An increase in flow velocity through a vessel increases shear stress, a major stimulus for enlargement of conduit vessels. This leads to an endothelial-dependent, nitric oxide-dependent enlargement of the vessel. Increased flow within muscle, in the absence of contractions, leads to an enhanced capillarity by intussusceptive angiogenesis, a process of capillary splitting by intraluminal longitudinal divide. In contrast, sprouting angiogenesis requires extensive endothelial cell proliferation, with degradation of the extracellular matrix to permit migration and tube formation. This occurs during muscle adaptations to chronic contractions and/or muscle overload. The angiogenic growth factor VEGF appears to be an important element in angiogenesis. Recent advances in research have identified hemodynamic and mechanical stimuli that upregulate angiogenic processes, demonstrated a complexity of potent growth factors and interactions with their corresponding receptors, detected an interaction of cellular signaling events, and identified important tissue reorganization processes that must be coordinated to effect vascular remodeling. It is likely that much of this information is applicable to the vascular remodeling that occurs in response to exercise and/or muscle contractions.

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Notch2 Suppression Mimicking Changes in Human Pulmonary Hypertension Modulates Notch1 and Promotes Endothelial Cell Proliferation

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00125.2021 ◽

2021 ◽

Author(s):

Sanghamitra Sahoo ◽

Yao Li ◽

Daniel de Jesus ◽

John Charles Sembrat II ◽

Mauricio M Rojas ◽

...

Keyword(s):

Cell Proliferation ◽

Endothelial Cells ◽

Endothelial Cell ◽

Target Genes ◽

Pulmonary Arteries ◽

Notch Receptor ◽

Endothelial Cell Proliferation ◽

Tissue Samples ◽

Endothelial Proliferation ◽

Human Pulmonary Artery

Pulmonary arterial hypertension (PAH) is a fatal cardiopulmonary disease characterized by increased vascular cell proliferation with resistance to apoptosis and occlusive remodeling of the small pulmonary arteries in humans. The Notch family of proteins are proximal signaling mediators of an evolutionarily conserved pathway that effect cell proliferation, fate determination, and development. In endothelial cells (ECs), Notch receptor 2 (Notch2) has been shown to promote endothelial apoptosis. However, a pro- or anti-proliferative role for Notch2 in pulmonary endothelial proliferation and ensuing PAH is unknown. Herein, we postulated that suppressed Notch2 signaling drives pulmonary endothelial proliferation in the setting of PAH. We observed that levels of Notch2 are ablated in lung and PA tissue samples from PAH patients compared to non-PAH controls. Interestingly, Notch2 expression was attenuated in human pulmonary artery endothelial cells (hPAECs) exposed to vasoactive factors including hypoxia, TGFβ, ET-1, and IGF-1. Gene silencing of Notch2 increased EC proliferation and reduced apoptosis. At the molecular level, Notch2-deficient hPAECs activated Akt, Erk1/2 and anti-apoptotic protein Bcl-2, and reduced levels of p21cip and Bax. Intriguingly, loss of Notch2 elicits a paradoxical activation of Notch1 and transcriptional upregulation of canonical Notch target genes Hes1, Hey1 and Hey2. Further, reduction in Rb and increased E2F1 binding to the Notch1 promoter appear to explain the upregulation of Notch1. In aggregate, our results demonstrate that loss of Notch2 derepresses Notch1 and elicits aberrant EC hallmarks of PAH. The data underscore a novel role for Notch in the maintenance of endothelial cell homeostasis.

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Kallistatin Inhibits Endothelial Cell Proliferation, Migration and Adhesion in Vitro and Angiogenesis in the Ischemic Hindlimb of Rats

Hypertension ◽

10.1161/hyp.36.suppl_1.706-e ◽

2000 ◽

Vol 36 (suppl_1) ◽

pp. 706-707

Author(s):

Robert Q Miao ◽

Jun Agata ◽

Lee Chao ◽

Julie Chao

Keyword(s):

Cell Proliferation ◽

Endothelial Cell ◽

Gene Delivery ◽

Fluorescent Protein ◽

Regional Blood Flow ◽

Endothelial Cell Proliferation ◽

Hek 293

P76 Kallistatin is a serine proteinase inhibitor (serpin) which has multifunctions including regulation of tissue kallikrein activity, blood pressure, inflammation and neointima hyperplasia. In this study, we investigated the potential role of kallistatin in vascular biology by studying its effects on the proliferation, migration and adhesion of cultured primary human endothelial cells in vitro, and angiogenesis in the ischemic hindlimb of rats. Purified kallistatin significantly inhibits cultured endothelial cell proliferation, migration and adhesion induced by VEGF or bFGF. To further investigate the role of kallistatin in vascular growth in vivo, we prepared adenovirus carrying the human kallistatin gene under the control of the cytomegalovirus promoter/enhancer (Ad.CMV-cHKBP). Expression of recombinant human kallistatin in HEK 293 cells transfected with Ad.CMV-cHKBP was identified by a specific ELISA. The effect of adenovirus-mediated kallistatin gene delivery on angiogenesis was evaluated in a rat model of hindlimb ischemia. Adenovirus carrying the human kallistatin or green fluorescent protein (GFP) gene were injected locally into the ischemic adductor at the time of surgery. Histological and morphometric analysis at 14 days post injection showed that adenovirus-mediated kallistatin gene delivery significantly reduced capillary density in the ischemic muscle as compared to that of control rats injected with GFP. The anti-angiogenic effect of kallistatin was associated with reduced regional blood flow in the ischemic hindlimb measured by microsphere assays. Expression of human kallistatin was identified in the injected muscle and immunoreactive human kallistatin levels were measured in the muscle and in the circulation of rats following kallistatin gene delivery. These results demonstrate a novel role of kallistatin in the inhibition of angiogenesis and in vascular remodeling.

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Endostatin: A Promising Drug for Antiangiogenic Therapy

The International Journal of Biological Markers ◽

10.1177/172460089901400412 ◽

1999 ◽

Vol 14 (4) ◽

pp. 263-267 ◽

Cited By ~ 13

Author(s):

L. Cirri ◽

S. Donnini ◽

L. Morbidelli ◽

P. Chiarugi ◽

M. Ziche ◽

...

Keyword(s):

Cell Proliferation ◽

Endothelial Cell ◽

Growth Factor ◽

Antiangiogenic Therapy ◽

Specific Inhibitor ◽

Angiogenesis Inhibitors ◽

Endothelial Cell Proliferation ◽

Platelet Factor ◽

Collagen Xviii ◽

And Migration

Angiogenesis, the formation of new blood vessels from existing capillaries, is critical for tumors to grow beyond a few in size. Tumor cells produce one or more angiogenic factors including fibroblast growth factor and vascular endothelial growth factor. Surprisingly, antiangiogenic factors or angiogenesis inhibitors have been isolated from tumors. Some angiogenesis inhibitors, such as angiostatin, are associated with tumors while others, such as platelet-factor 4 and interferon-alpha are not. Endostatin, a C-terminal product of collagen XVIII, is a specific inhibitor of endothelial cell proliferation, migration and angiogenesis. The mechanism by which endostatin inhibits endothelial cell proliferation and migration is unknown. Endostatin was originally expressed in a prokaryotic system and, late, in a yeast system, thanks to which it is possible to obtain a sufficient quantity of the protein in a soluble and refolded form to be used in preclincial and clinical trials.

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MODULATION of PROSTACYCLIN PRODUCTION BY HUMAN UMBILICAL VEIN ENDOTHELIAL CELLS WITH ECGF/HEPARIN MEDIUM : ROLE OF CELLULAR DENSITY AT CONFLUENCE

10.1055/s-0038-1643376 ◽

1987 ◽

Author(s):

O BOUTHERIN-FALSON ◽

N BLAES

Keyword(s):

Endothelial Cells ◽

Endothelial Cell ◽

Growth Factor ◽

Umbilical Vein ◽

Calf Serum ◽

Lower Amount ◽

Endothelial Cell Proliferation ◽

Human Umbilical Vein ◽

Umbilical Vein Endothelial Cells

Prostacyclin (PGI2) is a major product of arachidonic acid metabolism in vascular endothelial cells. In addition to the role of exogenous agents, its production could be modulated by culture conditions : proliferative state, medium renewal, subcultivation... The use of endothelial cell growth factor (ECGF) associated with heparin has been shown to improve human endothelial cell proliferation. Here we report that human umbilical vein endothelial cells (HUVEC) grown in that medium produce less prostacyclin than without growth factor.HUVEC were cultured in RPMI-199 1:1 + 20% fetal calf serum, added or not with ECGF (Bovine hypothalamus extract BTI Cambridge, 24 ug/ml) and heparin (from porcine intestinal mucosa, Signa, 90 ug/ml). After 4 days in culture, medium was removed and replaced by Tyrode Hepes buffer and basal production was measured after 20 min. Cells were then submitted to 5 min thrombin to assess PGI2 production in stimulated conditions. PGI2 production was estimated by specific radioimmunoassay for 6 keto PGFjalpha. For each point, cell number in the culture was counted after Trypsin EDTA treatment. In the present study, cells grown in ECGF-heparin medium produce lower amount of PGI2, compared to heparin or control medium. This result was observed in both basal and stimulated conditions. For each medium (ECGF-heparin, heparin, control), correlations between PGI2 production per cell and log cell density were shown to be significantly negative.These observations suggest that ECGF effect on PGI2 production could be a consequence of its growth factor activity, notably by the fact that it leads to an endothelial monolayer made of more numerous cells. Since it is now suggested by a number of clinical observations that PGI2 is rather produced in pathological conditions, culture models showing a weak production of PGI2 appear in that connection doser to the physiological conditions.

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