Vasa Vasorum Neovascularization Research Articles

Adventitial Vasa Vasorum Neovascularization in Femoral Artery of Type 2 Diabetic Patients with Macroangiopathy Is Associated with Macrophages and Lymphocytes as well as the Occurrence of Cardiovascular Events.

This study was conducted to assess the relationship between adventitial vasa vasorum neovascularization (VVn) in femoral artery of type 2 diabetic patients with macroangiopathy and the recruitment of macrophages and lymphocytes, and to relate the density of VVn to the occurrence of cardiovascular events. Femoral artery samples were obtained from amputation cases. A total of 55 type 2 diabetic patients with macroangiopathy, 15 autopsy cases with type 2 diabetes without atherosclerosis. Hematoxylin and eosin (H&E) staining to observe the histopathological features; Victoria blue staining to analyze the histological features; immunohistochemistry (CD34, CD68, CD20, and CD3) to determine the VVn density and the expression of macrophages, B lymphocytes, and T lymphocytes. Type 2 diabetic patients with macroangiopathy showed a higher mean adventitial VVn density in femoral artery (48.40 ± 9.39 no./mm2) than patients with type 2 diabetes without atherosclerosis (19.75 ± 6.28 no./mm2) (p < 0.01). In addition, the VVn density was positively associated with the expression of CD68 macrophages (r = 0.62, p < 0.01) and CD20 B lymphocytes (r = 0.59, p < 0.01). Type 2 diabetic patients with high VVn density showed more adverse cardiovascular events (27/35 vs. 8/20 events, p = 0.006). In multivariable analysis adjusted for main risk factors for cardiovascular disease, VVn was still independently associated with adverse cardiovascular events (p = 0.01). VVn density in type 2 diabetic patients with macroangiopathy is positively correlated with the adventitial immune-inflammatory cell numbers and the development of atherosclerotic lesions. Furthermore, VVn density is associated with adverse cardiovascular events.

Effect and Mechanism of Si-Miao-Yong-An on Vasa Vasorum Remodeling in ApoE-/- Mice with Atherosclerosis Vulnerable Plague.

Objective: To observe the effect of Si-Miao-Yong-An (SMYA) on atherosclerosis (AS) vulnerable plaques, and to further explore the mechanism by vasa vasorum (VV) angiogenesis and maturation as an entry point. Methods: SPF-class healthy male ApoE−/− mice were randomized into model group, simvastatin group and SMYA group, and C57BL/6 mice were used as the control group. After 8 weeks of intervention, the pathological morphology of plaque was observed by HE staining; the VV density in plaque and aortic adventitia were observed by immunohistochemistry; VV maturation was measured by double-labelling immunofluorescence; the critical proteins of HIF-1α-Apelin/APJ and Ang-1/Tie signal pathways were detected by western blotting. Results: SMYA decreased the plaque area and the ratio of plaque to lumen area; increased the minimum thickness of fibrous cap and its effect was greater than simvastatin. SMYA suppressed the VV neovascularization; promoted smooth muscle cells recruitment and VV maturation, which maintained plaque stability; its effect was obviously superior to simvastatin. SMYA deceased the expression of HIF-1α, Apelin, APJ, Phospho-MEK1/2 (Ser217/221), Phospho-p44/42 MAPK (Erk1/2) (Thr202/Tyr204), Phospho-p70 S6 Kinase (Thr421/Ser424), Ang-2 and Tie-2; it also increased the expression of Ang-1, Phospho-Akt (Ser473), Phospho-FOXO1 (Ser256) and Survivin. Conclusions: SMYA can decrease the AS plaque area in ApoE−/− mice, suppress the VV neovascularization and promote the VV maturation, and stabilize AS vulnerable plaque. The mechanism could be regulating the HIF-1α-Apelin/APJ and Ang-1/Tie signal pathways.

The role of oxygen transport in atherosclerosis and vascular disease.

Atherosclerosis and vascular disease of larger arteries are often associated with hypoxia within the layers of the vascular wall. In this review, we begin with a brief overview of the molecular changes in vascular cells associated with hypoxia and then emphasize the transport mechanisms that bring oxygen to cells within the vascular wall. We focus on fluid mechanical factors that control oxygen transport from lumenal blood flow to the intima and inner media layers of the artery, and solid mechanical factors that influence oxygen transport to the adventitia and outer media via the wall's microvascular system—the vasa vasorum (VV). Many cardiovascular risk factors are associated with VV compression that reduces VV perfusion and oxygenation. Dysfunctional VV neovascularization in response to hypoxia contributes to plaque inflammation and growth. Disturbed blood flow in vascular bifurcations and curvatures leads to reduced oxygen transport from blood to the inner layers of the wall and contributes to the development of atherosclerotic plaques in these regions. Recent studies have shown that hypoxia-inducible factor-1α (HIF-1α), a critical transcription factor associated with hypoxia, is also activated in disturbed flow by a mechanism that is independent of hypoxia. A final section of the review emphasizes hypoxia in vascular stenting that is used to enlarge vessels occluded by plaques. Stenting can compress the VV leading to hypoxia and associated intimal hyperplasia. To enhance oxygen transport during stenting, new stent designs with helical centrelines have been developed to increase blood phase oxygen transport rates and reduce intimal hyperplasia. Further study of the mechanisms controlling hypoxia in the artery wall may contribute to the development of therapeutic strategies for vascular diseases.

Eosinophilic inflammation in spontaneous coronary artery dissection: A potential therapeutic target?

Spontaneous coronary artery dissection (SCAD), defined as non-traumatic, non-iatrogenic dissociation of coronary vessel wall resulting from intimal disruption or intramural hemorrhage, represents an important cause of sudden death and myocardial infarction among young or middle-aged women without conventional risk factors for atherosclerosis. On histopathological examination, SCAD is featured by prominent eosinophilic infiltration of the adventitia or periadventitial layer of coronary artery. It has been estimated that approximately 15–30% of SCAD patients experience recurrent episodes of dissection despite medical therapy. Preliminary evidence suggests that injury to the vascular endothelium and myocytes in the arterial wall may be explained by cytotoxic products released from eosinophils in response to inflammatory mediators. In addition, neovascularization of vasa vasorum and dilatation of intimal capillaries may be stimulated by localized eosinophils. Newly formed fragile vasa vasorum may disrupt due to high intraluminal pressure from the interconnected capillary network, leading to the expansion of intramural hemorrhage. It is hypothesized that anti-inflammatory therapy targeting eosinophilic coronary periarteritis would be effective in preventing the recurrence of SCAD by promoting the healing of dissection. The article delineates the biological plausibility, empirical data, and future perspective regarding eosinophilic inflammation as a potential therapeutic target for SCAD.

Endoplasmic reticulum stress in perivascular adipose tissue promotes destabilization of atherosclerotic plaque by regulating GM-CSF paracrine

BackgroundPerivascular adipose tissue (PVAT) accelerates plaque progression and increases cardiovascular risk. We tested the hypothesis that PVAT contributed to plaque vulnerability and investigated whether endoplasmic reticulum stress (ER stress) in PVAT played an important role in vulnerable plaque.MethodsWe transplanted thoracic aortic PVAT or subcutaneous adipose tissue as a control, from donor mice to carotid arteries of recipient apolipoprotein E deficient (apoE−/−) mice after removing carotid artery collar placed for 6 weeks. Two weeks after transplantation, ER stress inhibitor 4-phenyl butyric acid (4-PBA) was locally administrated to the transplanted PVAT and then animals were euthanized after 4 weeks. Immunohistochemistry was performed to quantify plaque composition and neovascularization. Mouse angiogenesis antibody array kit was used to test the angiogenic factors produced by transplanted adipose tissue. In vitro tube formation assay, scratch wound migration assay and mouse aortic ring assay were used to assess the angiogenic capacity of supernatant of transplanted PVAT.ResultsUltrastructural detection by transmission electron microscopy showed transplanted PVAT was a mixed population of white and brown adipocytes with abundant mitochondria. Transplanted PVAT increased the intraplaque macrophage infiltration, lipid core, intimal and vasa vasorum neovascularization and MMP2/9 expression in plaque while decreased smooth muscle cells and collagen in atherosclerotic plaque, which were restored by local 4-PBA-treatment. Antibody array analysis showed that 4-PBA reduced several angiogenic factors [Granulocyte Macrophage Colony Stimulating Factor (GM-CSF), MCP-1, IL-6] secreted by PVAT. Besides, conditioned medium from 4-PBA treated-PVAT inhibited tube formation and migration capacity of endothelial cells and ex vivo mouse aortic ring angiogenesis compared to conditioned medium from transplanted PVAT. mRNA expression and protein levels of GM-CSF were markedly elevated in adipocytes under ER stress which would be suppressed by 4-PBA. In addition, ER stress enhanced NF-κB binding to the promoter of the mouse GM-CSF gene in adipocytes confirmed by Chromatin immunoprecipitation analyses.ConclusionsOur findings demonstrate that ER stress in PVAT destabilizes atherosclerotic plaque, in part through increasing GM-CSF paracrine via transcription factor NF-κB.

Abstract WP145: Presence of Vasa Vasorum Neovascularization on Optical Frequency Domain Imaging Predicts Progression of Carotid Artery Stenosis

Background: Vasa vasorum neovascularization (VVN) is one of the characteristics of vulnerable plaque. The purpose of this study was to assess VVN using optical frequency domain imaging (OFDI) between symptomatic and asymptomatic carotid artery plaques, and to know its association with progression of stenosis. Methods: The carotid artery plaques were examined before angioplasty using OFDI system (LUNAWAVE TM , Terumo). VVN was defined as a no-signal tubuloluminal structures recognized on at least 3 consecutive images. A total number of VVN was compared between symptomatic and asymptomatic plaques. The stenosis was evaluated by carotid duplex scan within one year. The lesion was diagnosed as ‘progressive’ when the stenotic degree and peak systolic velocity were increased. Results: A total of 60 patients (29 symptomatic, 11 progression) were included. VVN was detected in 54 patients (90%), the total number of VVN was significantly higher in progressive stenosis (8.9 ± 5.7 vs. 4.5 ± 3.8, p = 0.02). However, there was no relationship between the number of VVN and ischemic symptom. Conclusions: VVN was more frequently observed in progressive stenosis. Evaluation of VVN using OFDI might be useful to predict progression of carotid artery stenosis.

Tongxinluo mitigates atherogenesis by regulating angiogenic factors and inhibiting vasa vasorum neovascularization in apolipoprotein E-deficient mice.

Vasa vasorum (VV) neovascularization contributes to atherogenesis and its expansion and distribution is correlated with intraplaque expression of angiogenic factors. The present study investigated the roles of Tongxinluo (TXL), a traditional Chinese medication, on VV proliferation and atherogenesis. In vitro, TXL pre-treatment reversed the tumor necrosis factor-a (TNF-a) induced expression of vascular endothelial growth factor A (VEGF-A) and angiopoietin-1 (ANGPT-1) but not ANGPT-2, leading to increased ratio of ANGPT-1 to ANGPT-2. Consistently, TXL treatment (at a dosage of 0.38, 0.75, 1.5 g/kg/d, respectively) decreased the expression of VEGF-A while increased that of ANGPT-1 in early atherosclerotic lesions of apolipoprotein E deficient (apoE−/−) mice. On aortic ring assay, microvessels sprouting from aortas were significantly inhibited in TXL-treated mice. Moreover, VV neovascularization in plaques was markedly reduced with TXL treatment. Histological and morphological analysis demonstrated that TXL treatment reduced plaque burden, plaque size and changed the plaque composition. These data suggest that TXL inhibits early atherogenesis through regulating angiogenic factor expression and inhibiting VV proliferation in atherosclerotic plaque. Our study shed new light on the anti-atherosclerotic effect of TXL.

Microvasular and macrovascular complications in diabetes mellitus: Distinct or continuum?

Diabetes and related complications are associated with long-term damage and failure of various organ systems. The line of demarcation between the pathogenic mechanisms of microvascular and macrovascular complications of diabetes and differing responses to therapeutic interventions is blurred. Diabetes induces changes in the microvasculature, causing extracellular matrix protein synthesis, and capillary basement membrane thickening which are the pathognomic features of diabetic microangiopathy. These changes in conjunction with advanced glycation end products, oxidative stress, low grade inflammation, and neovascularization of vasa vasorum can lead to macrovascular complications. Hyperglycemia is the principal cause of microvasculopathy but also appears to play an important role in causation of macrovasculopathy. There is thought to be an intersection between micro and macro vascular complications, but the two disorders seem to be strongly interconnected, with micro vascular diseases promoting atherosclerosis through processes such as hypoxia and changes in vasa vasorum. It is thus imperative to understand whether microvascular complications distinctly precede macrovascular complications or do both of them progress simultaneously as a continuum. This will allow re-focusing on the clinical issues with a unifying perspective which can improve type 2 diabetes mellitus outcomes.

Abstract 14910: Vascular Cells Originating From Perivascular Adipose Tissue Contribute to Vasa Vasorum Neovascularization in Atherosclerosis

Introduction: Proliferation of vasa vasorum (VV) is observed in the adventitia of arteries with atherosclerotic plaques. It was reported that fat tissue transplantation to carotid artery exaggerated neointimal formation and VV proliferation after wire injury in a hypercholesterolemic mouse model. However, there is no in vivo histological evidence that vascular cells originating from perivascular adipose tissue (PAT) contribute to VV neovascularization. Methods: We established a new mouse model of atherosclerosis, in which the carotid artery is partially ligated (CPL) and exogenous adipose tissue is transplanted in the perivascular area (PVAT). The three branches (external and internal carotid, occipital) of the left carotid artery (LCA) of 20- to 25- week-old male apolipoprotein E-deficient (ApoE-/-) mice were ligated. Then epididymal adipose tissue from a donor ApoE-/- mouse was transplanted around the LCA (CPL+PVAT, n=5). Carotid partial ligation alone was performed as a control (CPL, n=3). After 8 weeks, on western type diet, LCA was harvested with PAT after biotinylated-Lycopersicon Esculentum (Tomato) lectin perfusion staining. Next, epididymal fat tissue from a male enhanced green fluorescent protein (EGFP) mouse was transplanted around the LCA of another set of male ApoE -/- mice after CPL (n=4). After 8 weeks, LCA was harvested with PAT after perfusion staining of microvessels, embedded in plastic resin, and observed under a confocal microscope. Results: The transplanted adipose tissue engrafted and atherosclerotic lesion developed in LCAs. Intima/media ratio of CPL+PVAT group was similar with that of CPL alone group (p=0.39). Whereas, VV density in adventitial area (outside the elastic lamina within a distance of the thickness of neointima plus media, excluding PAT) near three -fold increased than CPL alone group (p&lt;0.05). In the EGFP fat transplanted mice, a significant portion of VV was GFP positive (GFP positive /total microvessels in adventitia: 12.5 ± 6.2 % ). Conclusions: The vascular cells derived from PAT contribute to VV neovascularization, at least in part, in atherosclerosis.

Quantification of Adventitial Vasa Vasorum Vascularization in Double-injury Restenotic Arteries.

Background:Accumulating evidence indicates a potential role of adventitial vasa vasorum (VV) dysfunction in the pathophysiology of restenosis. However, characterization of VV vascularization in restenotic arteries with primary lesions is still missing. In this study, we quantitatively evaluated the response of adventitial VV to vascular injury resulting from balloon angioplasty in diseased arteries.Methods:Primary atherosclerotic-like lesions were induced by the placement of an absorbable thread surrounding the carotid artery of New Zealand rabbits. Four weeks following double-injury induced that was induced by secondary balloon dilation, three-dimensional patterns of adventitial VV were reconstructed; the number, density, and endothelial surface of VV were quantified using micro-computed tomography. Histology and immunohistochemistry were performed in order to examine the development of intimal hyperplasia.Results:Results from our study suggest that double injured arteries have a greater number of VV, increased luminal surface, and an elevation in the intima/media ratio (I/M), along with an accumulation of macrophages and smooth muscle cells in the intima, as compared to sham or single injury arteries. I/M and the number of VV were positively correlated (R2 = 0.82, P < 0.001).Conclusions:Extensive adventitial VV neovascularization occurs in injured arteries after balloon angioplasty, which is associated with intimal hyperplasia. Quantitative assessment of adventitial VV response may provide insight into the basic biological process of postangioplasty restenosis.

Adventitial Vasa Vasorum

To the Editor: I reviewed the article Quantification of adventitial vasa vasorum (VV) vascularization in double-injury restenotic arteries by Meng et al.[1] with great interest, which described their experiment about adventitial VV and postangioplasty restenosis. Percutaneous transluminal angioplasty is now widely used for the treatment of atherosclerotic lesions in various arteries. Restenosis is a major concern following angioplasty, and yet with no good solutions. Previous experimental studies suggested that there is an association between VV and atherosclerotic plaque formation and intimal hyperplasia. As occlusion of VV correlates well with neointima formation, but inhibition of VV neovascularization correlates with reduced plaque growth,[2] VV may play several different roles in different phases of atherosclerosis or postangioplasty restenosis. The causative mechanism is still unclear.

Vasa vasorum in atherosclerosis and clinical significance.

Atherosclerosis is a chronic inflammatory disease that leads to several acute cardiovascular complications with poor prognosis. For decades, the role of the adventitial vasa vasorum (VV) in the initiation and progression of atherosclerosis has received broad attention. The presence of VV neovascularization precedes the apparent symptoms of clinical atherosclerosis. VV also mediates inflammatory cell infiltration, intimal thickening, intraplaque hemorrhage, and subsequent atherothrombosis that results in stroke or myocardial infarction. Intraplaque neovessels originating from VV can be immature and hence susceptible to leakage, and are thus regarded as the leading cause of intraplaque hemorrhage. Evidence supports VV as a new surrogate target of atherosclerosis evaluation and treatment. This review provides an overview into the relationship between VV and atherosclerosis, including the anatomy and function of VV, the stimuli of VV neovascularization, and the available underlying mechanisms that lead to poor prognosis. We also summarize translational researches on VV imaging modalities and potential therapies that target VV neovascularization or its stimuli.

Traditional Chinese medication Tongxinluo inhibits inflammatory angiogenesis via Bmx/NF- B/MAPK pathways

The aim of this article is to examine the effect of the traditional Chinese medication Tongxinluo (TXL) on atherosclerotic plaque angiogenesis and stabilization and to explore the mechanism involved. Apolipoprotein E-deficient ( apoE−/− ) mice were fed a high-fat diet for 20 weeks, and then divided into four groups for 16 weeks' treatment: control (equal volume of buffer) and low-, medium-, and high-dose TXL (0.38, 0.75, and 1.5 g/kg/day, respectively). Vasa vasorum (VV) were identified by perfusion of biotinylated Lycopersicon esculentum (Tomato) lectin. The cellular effect of TXL on tumour necrosis factor α (TNF-α)-stimulated angiogenesis was explored in human umbilical vein endothelial cells. Histology revealed that VV neovascularization was dose-dependently reduced by TXL treatment. Plaque area was smaller with TXL than control treatment and levels of inflammatory cytokines, matrix metalloproteinase 2, and vascular endothelial growth factor A were deceased in TXL-treated mice. Tongxinluo significantly inhibited TNF-α-induced endothelial cell migration, tube formation, and monocyte adhesion in vitro . The mechanism mediating the therapeutic effects of TXL involved inhibited activation of bone marrow kinase in chromosome X (Bmx) and nuclear factor kappa B (NF-κB) and down-regulated phosphorylation of the mitogen-activated protein kinase (MAPK) family members c-Jun N-terminal kinase and p38, but not extracellular signal-regulated kinase 1/2. Tongxinluo inhibits VV proliferation and atherosclerosis progression, thus stabilizing plaque in apoE−/− mice. The anti-angiogenic effects of TXL on atherosclerosis might be attributed to inhibiting inflammatory angiogenesis via Bmx/NF-κB/MAPK pathways.

Abstract 409: Is Accelerated Atherosclerosis a Microvascular Complication of Diabetes?

Introduction: The complications of diabetes have traditionally been categorized as micro- or macrovasculature in nature. Individuals with diabetes are at an increased risk of macrovascular complications, including cardiovascular disease and stroke, and also suffer from microvascular disorders including retinopathy, nephropathy and neuropathy. There is increasing evidence these micro- and macrovascular conditions may be linked. Our objective is to determine if direct effects of hyperglycemia on a specific microvascular bed, the vasa vasorum, promotes diabetes-associated accelerated atherosclerosis. Methods and Results: The effects of hyperglycemia on retinal and vasa vasorum neovascularization and aortic atherogenesis were examined in streptozotocin-injected apolipoprotein-E deficient (ApoE-/-) mice and normoglycemic ApoE-/- controls. Microvessel densities of the retina and vasa vasorum were quantified at 5, 10, 15 and 20 weeks of age. Atherosclerotic lesion volume in the ascending aorta was determined at the same time points. The expression levels of pro-angiogenic factors, VEGF and VEFGR2, were also determined. Data from normoglycemic ApoE-deficient mice indicate that there is an expansion in vasa vasorum density as the atherosclerotic lesion area increases. In contrast, hyperglycemic ApoE-/- mice have significantly larger atherosclerotic lesions (2 fold, P&lt;0..05) but have no detectible neovascularization of the vasa vasorum A deficiency in VEGF expression in the artery walls of the hyperglycemic mice may explain lack of neovascularization. Conclusions: These findings indicate that the microvessel structure of the vasa vasorum is altered by hyperglycaemia. The development and progression of atherosclerosis in hyperglycemic ApoE-deficient mice directly correlates with, and may be influenced by, microvascular changes.

High proliferative potential endothelial colony-forming cells contribute to hypoxia-induced pulmonary artery vasa vasorum neovascularization

Angiogenic expansion of the vasa vasorum (VV) is an important contributor to pulmonary vascular remodeling in the pathogenesis of pulmonary hypertension (PH). High proliferative potential endothelial progenitor-like cells have been described in vascular remodeling and angiogenesis in both systemic and pulmonary circulations. However, their role in hypoxia-induced pulmonary artery (PA) VV expansion in PH is not known. We hypothesized that profound PA VV neovascularization observed in a neonatal calf model of hypoxia-induced PH is due to increased numbers of subsets of high proliferative cells within the PA adventitial VV endothelial cells (VVEC). Using a single cell clonogenic assay, we found that high proliferative potential colony-forming cells (HPP-CFC) comprise a markedly higher percentage in VVEC populations isolated from the PA of hypoxic (VVEC-Hx) compared with control (VVEC-Co) calves. VVEC-Hx populations that comprised higher numbers of HPP-CFC also demonstrated markedly higher expression levels of CD31, CD105, and c-kit than VVEC-Co. In addition, significantly higher expression of CD31, CD105, and c-kit was observed in HPP-CFC vs. the VVEC of the control but not of hypoxic animals. HPP-CFC exhibited migratory and tube formation capabilities, two important attributes of angiogenic phenotype. Furthermore, HPP-CFC-Co and some HPP-CFC-Hx exhibited elevated telomerase activity, consistent with their high replicative potential, whereas a number of HPP-CFC-Hx exhibited impaired telomerase activity, suggestive of their senescence state. In conclusion, our data suggest that hypoxia-induced VV expansion involves an emergence of HPP-CFC populations of a distinct phenotype with increased angiogenic capabilities. These cells may serve as a potential target for regulating VVEC neovascularization.

Thalidomide influences atherogenesis in aortas of ApoE−/−/LDLR−/− double knockout mice: a nano-CT study

Plaque progression in atherosclerosis is closely connected to angiogenesis due to vasa vasorum (VV) growth. Objective of this study was to determine the unknown long-term effect of thalidomide on adventitial VV neovascularization and plaque progression using nano-focussed computed tomography (nano-CT). Proliferation and migration assays in human coronary artery endothelial cells (HCAEC) measured number of viable cells after incubation with thalidomide. Male ApoE−/−/LDLR−/− (AL) mice (n = 5) received a thalidomide containing western diet (WD) over 29 weeks. Another five male AL mice (WD without thalidomide) served as control group. Descending aortas were scanned with nano-CT at (1.5 μm)3 isotropic voxel size. Number and area of adventitial VV as well as plaque cross sectional area were measured. Results were complemented by histology. Thalidomide inhibited proliferation and migration of HCAEC dose-dependently. VV neovascularization decreased in number per cross section (7.66 ± 0.301 vs. 8.62 ± 0.164, p < 0.001) and in cross sectional area (0.0183 ± 0.0011 vs. 0.0238 ± 0.0008 mm2, p < 0.001). Cross sectional area of plaque decreased significantly when treated with thalidomide (0.57 ± 0.0187 vs. 0.803 ± 0.0148 mm2, p < 0.001). Nano-CT imaging revealed a reduced plaque growth and VV neovascularization after long-term application of thalidomide. Therefore, nano-CT can be considered as a new method to detect therapeutic effects in experimental models of atherosclerosis.

In vivo detection of vasa vasorum neovascularization using intravascular ultrasound: a comparison between acute coronary syndrome and stable angina pectoris

In vivo detection of vasa vasorum neovascularization using intravascular ultrasound: a comparison between acute coronary syndrome and stable angina pectoris

Temporal Characterization of the Functional Density of the Vasa Vasorum by Contrast-Enhanced Ultrasonography Maximum Intensity Projection Imaging

We sought to determine whether contrast-enhanced ultrasound (CEU) microangiography with maximum intensity projection (MIP) processing could temporally evaluate proliferation of the vasa vasorum (VV) in a model of mural hemorrhage. Expansion of the VV and plaque neovascularization contributes to plaque growth and instability and may be triggered by a variety of stimuli, including vascular hemorrhage. However, quantitative in vivo methods for temporal assessment of VV remodeling are lacking. In 24 rabbits fed a high-fat diet, either autologous whole blood or saline was percutaneously injected into the media-adventitia of the femoral artery using ultrahigh-frequency ultrasound guidance. Functional VV density at the injection site and contralateral control artery was assessed 1, 2, and 6 weeks after injection with CEU imaging with MIP processing. In vitro studies with renathane microtubes were also performed to validate linear density measurement with CEU and MIP processing. In vitro studies demonstrated that MIP processing of CEU data reflected the relative linear density of vessels in a manner that was relatively independent of contrast concentration or microtube flow rate. On CEU with MIP, there was a 3-fold increase in femoral artery VV microvascular density at 1 and 2 weeks after blood injection (p < 0.01 vs. contralateral control), whereas VV density increased minimally after saline injection. At 6 weeks, VV vascular density decreased in blood-treated vessels and was not different from saline-injected or contralateral control vessels. CEU with MIP processing can provide quantitative data on temporal changes in the functional density of the VV. This method may be useful for evaluating high-risk features of plaque neovascularization or response to therapies aimed at plaque neovessels.

Akt pathway is hypoactivated by synergistic actions of diabetes mellitus and hypercholesterolemia resulting in advanced coronary artery disease

Atherosclerosis is an inflammatory process leading to enhanced cellular proliferation, apoptosis, and vasa vasorum (VV) neovascularization. While both diabetes mellitus (DM) and hypercholesterolemia (HC) predispose to atherosclerosis, the precise interaction of these risk factors is unclear. Akt is a central node in signaling pathways important for inflammation, and we hypothesized that DM/HC would lead to aberrant Akt signaling and advanced, complex atherosclerosis. DM was induced in pigs by streptozotocin and HC by a high-fat diet. Animals were randomized to control (non-DM, non-HC), DM only, HC only, and DM/HC groups. Coronary artery homogenates were analyzed by immunoblotting for proteins involved in the Akt pathway, including phosphorylated (p)-Akt (Ser473), p-GSK-3beta (Ser9), activated NF-kappaB p65, and VEGF. Immunohistochemical staining for Ki67 (cell proliferation), terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) (apoptosis), and von Willebrand factor (vWF) (neovascularization) was performed. Neovascularization was visualized with micro-computerized tomography (CT). Only DM/HC animals developed advanced atherosclerosis and showed decreased p-Akt (Ser473) and p-GSK-3beta (Ser9) levels (P < 0.01 and P < 0.05, respectively). DM/HC arteries demonstrated increased cellular proliferation (P < 0.001), apoptosis (P < 0.01), and activation of NF-kappaB p65 (P < 0.05). Induction of DM/HC also resulted in significant VV neovascularization by enhanced VEGF expression (P < 0.05), increased vWF staining (P < 0.01), and increased density by micro-CT. In conclusion, DM and HC synergistically resulted in complex atherosclerosis associated with attenuated p-Akt (Ser473) levels. Aberrant Akt signaling correlated with increased inflammation, cellular proliferation, apoptosis, and VV neovascularization. Our results revealed a synergistic effect of DM and HC in triggering abnormal Akt signaling, resulting in advanced atherosclerosis.

OX40 ligand plays an important role in the development of atherosclerosis through vasa vasorum neovascularization

Atherosclerosis is characterized by infiltration of inflammatory cells and enhanced vasa vasorum formation, for which immunological mechanisms may be involved. OX40, a membrane-bound molecule of the tumour necrosis factor-receptor superfamily, is expressed by activated T-cells, while OX40 ligand (OX40L) is expressed in activated macrophages and endothelial cells. In this study, we thus examined whether the OX40/OX40L system is involved in the pathogenesis of atherosclerosis. We examined apolipoprotein E-deficient (ApoE(-/-)) mice and ApoE(-/-)/OX40L-double-deficient (ApoE(-/-)/OX40L(-/-)) mice fed on a high-fat diet for 8 weeks. The extent of aortic atheroma was significantly less in ApoE(-/-)/OX40L(-/-) mice compared with ApoE(-/-) mice. We also treated high-fat-fed ApoE(-/-) mice with or without MGP34 antibody (OX40L-specific neutralizing antibody) for 10 weeks. After the treatment, the extent of aortic atheroma was again significantly less in MGP34-treated mice compared with controls. Importantly, both vascular density in the aortic adventitia and vascular endothelial growth factor-induced angiogenesis in the Matrigel assay in vivo were significantly reduced in ApoE(-/-)/OX40L(-/-) mice compared with ApoE(-/-) mice. Finally, when high-fat-fed ApoE(-/-) mice were transplanted with bone marrow cells from either wild-type or OX40L(-/-) mice, the extent of aortic atheroma was comparable between the two groups. These results indicate that the vascular OX40/OX40L system plays an important role in the formation of vasa vasorum and subsequent atherosclerosis, suggesting that the vascular OX40/OX40L system might be a new therapeutic target of atherosclerosis.