Ultrastructural Study of Platelet Behavior and Interrelationship in Sprouting and Intussusceptive Angiogenesis during Arterial Intimal Thickening Formation

Platelets in atherosclerosis, bypass stenosis, and restenosis have been extensively assessed. However, a sequential ultrastructural study of platelets in angiogenesis during the early phases of these lesions has received less attention. Our objective was the study of platelets in angiogenesis and vessel regression during intimal thickening (IT) formation, a precursor process of these occlusive vascular diseases. For this purpose, we used an experimental model of rat occluded arteries and procedures for ultrastructural observation. The results show (a) the absence of platelet adhesion in the de-endothelialized occluded arterial segment isolated from the circulation, (b) that intraarterial myriad platelets contributed from neovessels originated by sprouting angiogenesis from the periarterial microvasculature, (c) the association of platelets with blood components (fibrin, neutrophils, macrophages, and eosinophils) and non-polarized endothelial cells (ECs) forming aggregates (spheroids) in the arterial lumen, (d) the establishment of peg-and-socket junctions between platelets and polarized Ecs during intussusceptive angiogenesis originated from the EC aggregates, with the initial formation of IT, and (e) the aggregation of platelets in regressing neovessels (‘transitory paracrine organoid’) and IT increases. In conclusion, in sprouting and intussusceptive angiogenesis and vessel regression during IT formation, we contribute sequential ultrastructural findings on platelet behavior and relationships, which can be the basis for further studies using other procedures.

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Intussusceptive Angiogenesis and Peg–Socket Junctions between Endothelial Cells and Smooth Muscle Cells in Early Arterial Intimal Thickening

International Journal of Molecular Sciences ◽

10.3390/ijms21218049 ◽

2020 ◽

Vol 21 (21) ◽

pp. 8049

Author(s):

Lucio Díaz-Flores ◽

Ricardo Gutiérrez ◽

Mª Pino García ◽

Sara Gayoso ◽

José Luís Carrasco ◽

...

Keyword(s):

Endothelial Cells ◽

Smooth Muscle ◽

Smooth Muscle Cells ◽

Muscle Cells ◽

Intimal Thickening ◽

Sprouting Angiogenesis ◽

Intussusceptive Angiogenesis ◽

Vessel Regression ◽

Ultrathin Sections ◽

Immunohistochemical Techniques

Angiogenesis in arterial intimal thickening (AIT) has been considered mainly in late AIT stages and only refers to sprouting angiogenesis. We assess angiogenesis during early AIT development and the occurrence of the intussusceptive type. For this purpose, we studied AIT development in (a) human arteries with vasculitis in gallbladders with acute cholecystitis and urgent (n = 25) or delayed (n = 20) cholecystectomy, using immunohistochemical techniques and (b) experimentally occluded arterial segments (n = 56), using semithin and ultrathin sections and electron microscopy. The results showed transitory angiogenic phenomena, with formation of an important microvasculature, followed by vessel regression. In addition to the sequential description of angiogenic and regressive findings, we mainly contribute (a) formation of intravascular pillars (hallmarks of intussusception) during angiogenesis and vessel regression and (b) morphological interrelation between endothelial cells (ECs) in the arterial wall and vascular smooth muscle cells (VSMCs), which adopt a pericytic arrangement and establish peg-and-socket junctions with ECs. In conclusion, angiogenesis and vessel regression play an important role in AIT development in the conditions studied, with participation of intussusceptive angiogenesis during the formation and regression of a provisional microvasculature and with morphologic interrelation between ECs and VSMCs.

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BMP-SMAD1/5 Signaling Regulates Retinal Vascular Development

Biomolecules ◽

10.3390/biom10030488 ◽

2020 ◽

Vol 10 (3) ◽

pp. 488 ◽

Cited By ~ 2

Author(s):

Andreas Benn ◽

Florian Alonso ◽

Jo Mangelschots ◽

Elisabeth Génot ◽

Marleen Lox ◽

...

Keyword(s):

Vascular Development ◽

Bmp Signaling ◽

Loop Formation ◽

Vessel Formation ◽

Sprouting Angiogenesis ◽

Intussusceptive Angiogenesis ◽

Morphogenetic Protein ◽

Vessel Regression ◽

Early Mouse ◽

Tip Cells

Vascular development is an orchestrated process of vessel formation from pre-existing vessels via sprouting and intussusceptive angiogenesis as well as vascular remodeling to generate the mature vasculature. Bone morphogenetic protein (BMP) signaling via intracellular SMAD1 and SMAD5 effectors regulates sprouting angiogenesis in the early mouse embryo, but its role in other processes of vascular development and in other vascular beds remains incompletely understood. Here, we investigate the function of SMAD1/5 during early postnatal retinal vascular development using inducible, endothelium-specific deletion of Smad1 and Smad5. We observe the formation of arterial-venous malformations in areas with high blood flow, and fewer and less functional tip cells at the angiogenic front. The vascular plexus region is remarkably hyperdense and this is associated with reduced vessel regression and aberrant vascular loop formation. Taken together, our results highlight important functions of SMAD1/5 during vessel formation and remodeling in the early postnatal retina.

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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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TNF-α-Induced YAP/TAZ Activity Mediates Leukocyte-Endothelial Adhesion by Regulating VCAM1 Expression in Endothelial Cells

International Journal of Molecular Sciences ◽

10.3390/ijms19113428 ◽

2018 ◽

Vol 19 (11) ◽

pp. 3428 ◽

Cited By ~ 14

Author(s):

Hyun-Jung Choi ◽

Na-Eun Kim ◽

Byeong Kim ◽

Miran Seo ◽

Ji Heo

Keyword(s):

Endothelial Cells ◽

Rho Gtpases ◽

Leukocyte Adhesion ◽

Hippo Pathway ◽

Specific Inhibitor ◽

Vascular Diseases ◽

Adhesive Properties ◽

Sprouting Angiogenesis ◽

Tnf Α

YAP/TAZ, a transcriptional co-activator of Hippo pathway, has emerged as a central player in vessel homeostasis such as sprouting angiogenesis and vascular barrier stabilization, during development. However, the role of YAP/TAZ in pathological angiogenesis remains unclear. Here, we demonstrated that YAP/TAZ is a critical mediator in leukocyte-endothelial adhesion induced by the vascular inflammatory cytokine TNF-α. YAP/TAZ was dephosphorylated, translocated from the cytosol to the nucleus, and activated by TNF-α in endothelial cells. A specific inhibitor of Rho GTPases suppressed the TNF-α-induced dephosphorylation of YAP. Knockdown of YAP/TAZ using siRNA significantly reduced the expression of the leukocyte adhesion molecule VCAM1 induced by TNF-α. The adhesion of monocytes to endothelial cells was also markedly reduced by YAP/TAZ silencing. However, knockdown of YAP/TAZ did not affect TNF-α-induced NF-κB signaling. Overall, these results suggest that YAP/TAZ plays critical roles in regulating TNF-α-induced endothelial cell adhesive properties without affecting the NF-κB pathway, and implicate YAP/TAZ as a potential therapeutic target for treating inflammatory vascular diseases.

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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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Macrophage (Drp1) Dynamin-Related Protein 1 Accelerates Intimal Thickening After Vascular Injury

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvbaha.120.314383 ◽

2020 ◽

Vol 40 (7) ◽

Cited By ~ 2

Author(s):

Ryuta Umezu ◽

Jun-ichiro Koga ◽

Tetsuya Matoba ◽

Shunsuke Katsuki ◽

Lixiang Wang ◽

...

Keyword(s):

Smooth Muscle ◽

Vascular Smooth Muscle ◽

Smooth Muscle Cells ◽

Vascular Smooth Muscle Cells ◽

Vascular Injury ◽

Mitochondrial Fission ◽

Vascular Diseases ◽

Intimal Thickening ◽

Related Protein ◽

Inflammatory Macrophages

Objective: Mitochondria consistently change their morphology in a process regulated by proteins, including Drp1 (dynamin-related protein 1), a protein promoting mitochondrial fission. Drp1 is involved in the mechanisms underlying various cardiovascular diseases, such as myocardial ischemia/reperfusion injury, heart failure, and pulmonary arterial hypertension. However, its role in macrophages, which promote various vascular diseases, is poorly understood. We therefore tested our hypothesis that macrophage Drp1 promotes vascular remodeling after injury. Method and Results: To explore the selective role of macrophage Drp1, we created macrophage-selective Drp1-deficient mice and performed femoral arterial wire injury. In these mice, intimal thickening and negative remodeling were attenuated at 4 weeks after injury when compared with control mice. Deletion of macrophage Drp1 also attenuated the macrophage accumulation and cell proliferation in the injured arteries. Gain- and loss-of-function experiments using cultured macrophages indicated that Drp1 induces the expression of molecules associated with inflammatory macrophages. Morphologically, mitochondrial fission was induced in inflammatory macrophages, whereas mitochondrial fusion was induced in less inflammatory/reparative macrophages. Pharmacological inhibition or knockdown of Drp1 decreased the mitochondrial reactive oxygen species and chemotactic activity in cultured macrophages. Co-culture experiments of macrophages with vascular smooth muscle cells indicated that deletion of macrophage Drp1 suppresses growth and migration of vascular smooth muscle cells induced by macrophage-derived soluble factors. Conclusions: Macrophage Drp1 accelerates intimal thickening after vascular injury by promoting macrophage-mediated inflammation. Macrophage Drp1 may be a potential therapeutic target of vascular diseases.

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Calcifying Matrix Vesicles and Atherosclerosis

BioMed Research International ◽

10.1155/2017/7463590 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7 ◽

Cited By ~ 19

Author(s):

Dimitry A. Chistiakov ◽

Veronika A. Myasoedova ◽

Alexandra A. Melnichenko ◽

Andrey V. Grechko ◽

Alexander N. Orekhov

Keyword(s):

Smooth Muscle ◽

Vascular Smooth Muscle ◽

Smooth Muscle Cells ◽

Vascular Smooth Muscle Cells ◽

Muscle Cells ◽

Matrix Vesicles ◽

Intimal Thickening ◽

Arterial Lumen ◽

Plaque Stabilization

Artery calcification is a well-recognized predictor of late atherosclerotic complications. In the intima media, calcification starts with apoptosis of vascular smooth muscle cells (VSMCs) and the release of calcifying matrix vesicles with diameter of 0.5–15 μm that can be observed microscopically. In complicated plaques, calcification is generally less frequent. Calcifying vesicles are released by proatherosclerotic VSMCs into the collagen-rich matrix. The vesicles can penetrate into the intima media and protrude into the arterial lumen and thereby may represent a potential cause of atherothrombosis. In calcified fibrolipid plaques, the rate of calcification is increased but is followed with healing of a lesion rupture and exhibited by further erosion and/or intimal thickening. Generally, calcification directly correlates with the apoptosis of VSMCs and macrophages accompanied by the release of osteogenic matrix vesicles. This is a hallmark of atherosclerosis-related apoptosis of VSMCs that is commonly released in plaque stabilization.

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An ultrastructural study of endothelial cells in branched regions of rat artery

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100084922 ◽

1991 ◽

Vol 49 ◽

pp. 124-125

Author(s):

V. C. Yang ◽

C. H. Kao

Keyword(s):

Endothelial Cells ◽

Blood Flow ◽

Ultrastructural Study ◽

Quantitative Methods ◽

Mechanical Stresses ◽

Intimal Thickening ◽

Transport Mechanisms ◽

Transendothelial Transport ◽

Initial Event ◽

Morphological Studies

Endothelial injuries in artery have long been considered as the initial event of the intimal thickening in atherogenesis. It has been noted clinically that some lesions tend to be situated at regions with the greatest mechanical stresses. These regions include branchings, bends, and narrowings. Physiological evidences showed that patterns of blood flow and mural tensions in these regions were notably different from those in the unbranched vessels. However, there have been no morphological studies on the endothelium about the branches of the arteries. Our experiment was designed for a comparison between the ultrastructrue of endothelia at the branched and the unbranched areas of the arteries in rats. The specific intention was to apply morphological quantitative methods to investigate the transendothelial transport mechanisms.

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

Cells ◽

10.3390/cells10102625 ◽

2021 ◽

Vol 10 (10) ◽

pp. 2625

Author(s):

Lucio Díaz-Flores ◽

Ricardo Gutiérrez ◽

Miriam González-Gómez ◽

María-del-Pino García ◽

Lucio Díaz-Flores ◽

...

Keyword(s):

Endothelial Cell ◽

Antiangiogenic Therapy ◽

Proliferation Index ◽

Endothelial Cell Proliferation ◽

Sprouting Angiogenesis ◽

Intussusceptive Angiogenesis ◽

Endothelial Proliferation ◽

Clinical Interest ◽

The Brain

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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Pericytes promote selective vessel regression to regulate vascular patterning

Blood ◽

10.1182/blood-2011-01-332338 ◽

2012 ◽

Vol 120 (7) ◽

pp. 1516-1527 ◽

Cited By ~ 68

Author(s):

Nicole Simonavicius ◽

Matthew Ashenden ◽

Antoinette van Weverwijk ◽

Siân Lax ◽

David L. Huso ◽

...

Keyword(s):

Endothelial Cell ◽

Network Formation ◽

Mouse Tumor ◽

Vascular Patterning ◽

Sprouting Angiogenesis ◽

Antiangiogenic Therapies ◽

Basement Membrane Component ◽

Vessel Regression ◽

Vessel Networks

Abstract Blood vessel networks form in a 2-step process of sprouting angiogenesis followed by selective branch regression and stabilization of remaining vessels. Pericytes are known to function in stabilizing blood vessels, but their role in vascular sprouting and selective vessel regression is poorly understood. The endosialin (CD248) receptor is expressed by pericytes associated with newly forming but not stable quiescent vessels. In the present study, we used the Endosialin−/− mouse as a means to uncover novel roles for pericytes during the process of vascular network formation. We demonstrate in a postnatal retina model that Endosialin−/− mice have normal vascular sprouting but are defective in selective vessel regression, leading to increased vessel density. Examination of the Endosialin−/− mouse tumor vasculature revealed an equivalent phenotype, indicating that pericytes perform a hitherto unidentified function to promote vessel destabilization and regression in vivo in both physiologic and pathologic angiogenesis. Mechanistically, Endosialin−/− mice have no defect in pericyte recruitment. Rather, endosialin binding to an endothelial associated, but not a pericyte associated, basement membrane component induces endothelial cell apoptosis and detachment. The results of the present study advance our understanding of pericyte biology and pericyte/endothelial cell cooperation during vascular patterning and have implications for the design of both pro- and antiangiogenic therapies.

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