Vessel Wall Remodeling Research Articles

Comparison of computer-aided quantitative measurement and physician visual assessment in the evaluation of intracranial atherosclerotic stenosis: a vessel wall magnetic resonance imaging study.

Intracranial atherosclerotic stenosis is a leading cause of ischemic stroke in China. Accurate assessment of intracranial atherosclerotic stenosis through imaging techniques is crucial for guiding therapeutic interventions and prognostic stratification. Vessel wall magnetic resonance imaging (VWMRI) has emerged as a reliable method for evaluating intracranial arterial vessels. With the advancement of technology, computer-aided quantitative measurement (CAQM) is increasingly used in imaging assessment. This study aimed to compare physician visual assessment (PVA) with CAQM in the VWMRI evaluation of intracranial atherosclerotic stenosis. This retrospective cross-sectional study consecutively enrolled patients diagnosed with intracranial atherosclerotic stenosis through imaging examinations at the Fourth Affiliated Hospital of China Medical University from December 2018 to December 2023. Clinical data were collected for analysis. Two radiologists independently and separately conducted CAQM and PVA on the VWMRI images of intracranial atherosclerotic stenosis patients. The imaging features evaluated encompassed stenosis severity, vessel wall remodeling, vessel wall thickening patterns, fibrous cap characteristics, lipid core ratio, and plaque enhancement degree. The study further assessed the discrepancies and concordance between the assessment results obtained from the two methods using paired sample t-tests, Wilcoxon signed-rank tests, and Cohen's kappa coefficient analysis. This study enrolled a total of 589 patients. The PVA time was shorter than CAQM (12.02±3.63 vs. 20.48±6.50 min). However, compared with digital subtraction angiography, the CAQM had a better area under the curve (0.88) than the PVA (0.80) in assessing luminal stenosis degree. The proportions of vessel wall remodeling (227/38.5%) and plaque surface irregularity (127/21.6%) evaluated by PVA were both lower than those by CAQM (438/74.4%, 171/29.0%). Meanwhile, no statistically significant differences were found in the patterns of wall thickening (P=0.12/0.39) and the proportion of plaque lipid core (P=0.65 and P=0.27), with good agreement between the two methods (K=0.67/0.85, K=0.97/0.94). While there were no statistical differences in the assessment of plaque enhancement degree in specific arteries (middle cerebral artery and basilar artery) (n=77/36, P=0.08/0.21), an overall statistical difference was observed (n=113, P=0.03). Additionally, there was poor agreement in assessing plaque enhancement degree, with Cohen's kappa values of 0.13 (-0.05 to 0.32) and 0.16 (-0.06 to 0.39). This study revealed disparities between PVA and CAQM in the evaluation of intracranial atherosclerotic stenosis of VWMRI. CAQM is recommended for assessing stenosis degree, vessel wall remodeling, and fibrous cap characteristics. However, PVA is suggested to assess wall thickening patterns and lipid core ratio to expedite diagnosis. Further research is needed to validate CAQM's superiority in evaluating plaque enhancement degrees.

Intensity of subarachnoid space inflammation corresponds to the evolution of vessel wall remodeling during the acute and chronic phases of bacterial meningitis

AbstractCerebrovascular alterations in acute bacterial meningitis significantly contribute to adverse patient outcomes, with reported complication rates ranging from 10% to 29%. Focal alterations in arterial lumens, leading to vasoconstriction, are common in cerebral ischemic and inflammatory conditions, such as bacterial meningitis, presenting neurological complications, such as seizures, brain swelling, hydrocephalus, hearing loss and ischemic or hemorrhagic brain damage. The observed arterial narrowing during meningitis is attributed to diverse factors, including direct encroachment by inflammatory exudate, vascular wall edema, vasospasm, and vasculitis due to cellular infiltration and vessel remodeling. Early‐stage constriction might result from a watery exudate's encroachment, whereas persistent inflammation leads to thicker exudates, attracting inflammatory cells and inducing arteriopathic growth factor synthesis. This process promotes structural modifications in the vessel wall, progressing from subintimal infiltration to organic intimal thickening, culminating in vasculitis and the risk of cerebral ischemia. Accordingly, this review seeks to more clearly delineate the intricate relationship between subarachnoid space inflammation and acute and chronic vessel wall remodeling during bacterial meningitis. Conceivably, understanding this pathological process holds promise in unveiling potential treatment avenues to improve patient outcomes, and reduced morbidity and mortality associated with cerebrovascular complications during bacterial meningitis.

Clinical implications of haemodynamics in symptomatic intracranial atherosclerotic stenosis by computational fluid dynamics modelling: a systematic review

BackgroundRecently, computational fluid dynamics (CFD) has been used to simulate blood flow of symptomatic intracranial atherosclerotic stenosis (sICAS) and investigate the clinical implications of its haemodynamic features, which were systematically...

306 Endothelial Infiltrating Regulatory B Cells and NK T Cells Precipitate Inflammatory Cascade That Leads to Aneurysmal Rupture

INTRODUCTION: Current literature examining the mechanisms delineating intracranial aneurysm development and subsequent rupture is sparse. Studies from decades prior defined the aneurysm model as being one largely driven by flow changes. However, the scope of these models is limited and does not fully explain why only a subset of patients with existing intracranial aneurysms subsequently go on to rupture. METHODS: We obtained aneurysm endothelial lining from 20 patients with ruptured, unruptured, sentinel hemorrhage, and recurrent aneurysms during endovascular coil embolization, which were processed and analyzed using mass spectrometry. RESULTS: Compared to unruptured aneurysms, ruptured aneurysms had significantly increased infiltrating populations of NK cells (5.5% vs 1.4%, p < 0.01), regulatory B cells (27.6% vs 16.0%, p < 0.05), and cytotoxic CD8 T cells (23.7% vs 13.5%, p < 0.05). To understand whether these cells were recruited at the time of rupture or whether they were present prior to the ictus event, we examined aneurysms that were treated after presenting with sentinel hemorrhages – again these patients had that same population of early-NK cells (7.5%, p = 0.2), suggesting that these cells were present at the nexus point immediately prior to rupture. Further, the regulatory B cells were even more prominent in the sentinel population, (45.6%, p < 0.01). CONCLUSIONS: These findings all point to a complex, coordinated immune response that is driving the remodeling of the aneurysm vessel wall. We interpret the results to suggest that regulatory B cell driven destabilization of the aneurysmal wall leads to a series of events; namely the recruitment of NK cells, subsequent inflammatory cascade, and ultimate rupture. While there remains much to be understood about this multi-faceted picture, these findings provide the basis for further studies looking at targets for adjunctive immune therapies in both our unruptured and ruptured patient populations.

Abstract WP170: Patients With Cerebral Microbleeds Are More Likely to Have Poor Collaterals at the Time of Mechanical Thrombectomy

Introduction: Collateral cerebrovasculature is important for the survival of penumbral tissue in patients with large vessel occlusive (LVO) stroke, and adequate collateralization is associated with favorable outcomes. The presence of cerebral microbleeds (CMB) have been implicated in vessel wall remodeling and impaired vasoreactivity. We investigated whether the presence of deep and/or lobar CMB predicts poor collateral recruitment in patients with LVO stroke who underwent thrombectomy (MT). Methods: We performed a retrospective, single-center study of adults who presented with LVO stroke and had MT between January 2012-June 2020. CT angiography of head prior to MT was used to assess collateral status with poor status defined as ≤50% filling and good status as >50% filling. CMBs were assessed using T2*-weighted gradient echo or susceptibility weighted magnetic resonance images. Location of CMB was further characterized as deep vs. lobar using consensus definitions. Poor stroke outcome was defined as modified Rankin Scale (mRS) ≥3 at 90 days. Multivariable logistic regressions were performed to evaluate the associations between CMB, CMB types (lobar, deep, lobar+deep) and poor collaterals after adjusting for vascular risk factors. Results: Consecutive 151 subjects were included (mean age 68±15 years, 47% women), with a median NIHSS of 18. CMB were identified in 57 subjects (37.4%). Of these, 20.5% had lobar CMB, 5.3% had deep CMB and 11.9% had combined lobar & deep CMB. Patients with CMB had higher odds of having poor collaterals compared to those without CMB (OR 1.56, 95% CI 1.09-2.23, P=0.015). The association of CMB with poor collaterals was strongest in patients with combined lobar & deep CMB (OR 4.78, 95% CI 1.43-15.93, P=0.011), compared with those with exclusively deep CMB (OR 2.78, 95% CI 0.44-17.62, P=0.278) or lobar CMB (OR 0.52, 95% CI 0.19-1.38, P=0.188). Patients with poor collaterals were more likely to have poor outcome compared with those with good collaterals (48.4% vs. 31.0%, P=0.03). Conclusion: Cerebral microbleeds are independently associated with poor collateral recruitment when adjusted for traditional vascular risk factors. Further study is warranted to elucidate the differential effects of CMB types on collateral recruitment.

The Contribution of Innate Immunity in Large-Vessel Vasculitis: Detangling New Pathomechanisms beyond the Onset of Vascular Inflammation.

Large-vessel vasculitis (LVV) are autoimmune and autoinflammatory diseases focused on vascular inflammation. The central core of the intricate immunological and molecular network resides in the disruption of the "privileged immune state" of the arterial wall. The outbreak, initially primed by dendritic cells (DC), is then continuously powered in a feed-forward loop by the intimate cooperation between innate and adaptive immunity. If the role of adaptive immunity has been largely elucidated, knowledge of the critical function of innate immunity in LVV is still fragile. A growing body of evidence has strengthened the active role of innate immunity players and their key signaling pathways in orchestrating the complex pathomechanisms underlying LVV. Besides DC, macrophages are crucial culprits in LVV development and participate across all phases of vascular inflammation, culminating in vessel wall remodeling. In recent years, the variety of potential pathogenic actors has expanded to include neutrophils, mast cells, and soluble mediators, including the complement system. Interestingly, new insights have recently linked the inflammasome to vascular inflammation, paving the way for its potential pathogenic role in LVV. Overall, these observations encourage a new conceptual approach that includes a more in-depth study of innate immunity pathways in LVV to guide future targeted therapies.

Application and reduction of a nonlinear hyperelastic wall model capturing ex vivo relationships between fluid pressure, area, and wall thickness in normal and hypertensive murine left pulmonary arteries.

Pulmonary hypertension is a cardiovascular disorder manifested by elevated mean arterial blood pressure (>20 mmHg) together with vessel wall stiffening and thickening due to alterations in collagen, elastin, and smooth muscle cells. Hypoxia-induced (type 3) pulmonary hypertension can be studied in animals exposed to a low oxygen environment for prolonged time periods leading to biomechanical alterations in vessel wall structure. This study introduces a novel approach to formulating a reduced order nonlinear elastic structural wall model for a large pulmonary artery. The model relating blood pressure and area is calibrated using ex vivo measurements of vessel diameter and wall thickness changes, under controlled pressure conditions, in left pulmonary arteries isolated from control and hypertensive mice. A two-layer, hyperelastic, and anisotropic model incorporating residual stresses is formulated using the Holzapfel-Gasser-Ogden model. Complex relations predicting vessel area and wall thickness with increasing blood pressure are derived and calibrated using the data. Sensitivity analysis, parameter estimation, subset selection, and physical plausibility arguments are used to systematically reduce the 16-parameter model to one in which a much smaller subset of identifiable parameters is estimated via solution of an inverse problem. Our final reduced one layer model includes a single set of three elastic moduli. Estimated ranges of these parameters demonstrate that nonlinear stiffening is dominated by elastin in the control animals and by collagen in the hypertensive animals. The pressure-area relation developed in this novel manner has potential impact on one-dimensional fluids network models of vessel wall remodeling in the presence of cardiovascular disease.

Abstract 16902: Molecular Basis of the Vascular Cell Phenotypic Switch and Wall Remodeling in Abdominal Aortic Aneurysm: NOX4 NADPH Oxidase-Derived Mitochondrial Oxidative Stress and DNA Damage

Vascular cells phenotypic changes and wall remodeling are the hallmarks of abdominal aortic aneurysm (AAA) pathology. Mitochondrial oxidative stress (mtOS) is associated with the vascular smooth muscle cells (SMC) and macrophage phenotypic switch. We previously reported that NOX4 NADPH oxidase expression is increased in cardiovascular cells in response to pathological insult inducing mtOS and dysfunction and vascular disease progression. We tested the hypothesis that NOX4-dependent mtOS and DNA damage induce vascular phenotypic changes and remodeling resulting in AAA progression. In angiotensin II (Ang II)-induced AAA model Apoe -/- / Nox4 Tg mice with mitochondria-targeted overexpression of NOX4 had the highest, whereas Apoe -/- / Nox4 -/- displayed the lowest incidence of AAA, abdominal aorta area and diameter as compared with Apoe -/- mice. The aortic wall ROS levels, oxidative DNA damage and DNA damage response markers, elastin degradation index, MMP2 expression, and macrophage infiltration were significantly higher in AngII-treated Apoe -/- / Nox4 TG mice compared with Apoe -/- or Apoe -/- / Nox4 -/- mice. Spectral flow cytometry analysis of AAA cell suspension from Ang II-infused mice revealed a decrease in contractile SMCs but an increase in macrophage-like SMC populations, as well as increased number of infiltrating pro-inflammatory macrophages in Apoe -/- / Nox4 TG mice. As compared with wild-type or Nox4 -/- mice, Ang II-treated SMC from Nox4 TG mice showed significantly elevated mtOS, DNA damage, dysfunction, as well as activation of cGAS-STING pathway and NLRP3/AIM2 inflammasome expression. Flow cytometry analysis of Ang II-treated Nox4 TG mice SMC contained a lower proportion of cells with contractile markers (ACTA2 + , MYH11 + , TAGLN + ) and a higher proportion of cells with macrophage-like markers (CD68 + , CD11b + , LGALS3 + ). These data suggest that NOX4-dependent mitochondrial DNA damage and activation of DNA-sensing pathways have a causal role in AAA development, leading to macrophage-like SMCs, increased inflammation, and vessel wall remodeling. NOX4 inhibition and mitochondrial function augmentation may be beneficial in preserving aortic wall integrity in AAA-susceptible patients.

Abstract 17143: Lorundrostat for Treatment of Obesity-Related, Aldosterone-Dependent Hypertension - An Endotype-Specific, Targeted Approach to the Treatment of Uncontrolled Hypertension

Hyperaldosteronism manifests as low renin hypertension (HTN) with endothelial dysfunction and vascular fibrosis. In the aging vasculature, these pathological changes may be exacerbated by non-genomic aldosterone signaling via GPER (GPR30), which is not inhibited by mineralocorticoid receptor antagonists (MRA). In trials with healthy subjects and patients with uncontrolled HTN, the novel, highly selective aldosterone synthase inhibitor, lorundrostat, reduced median morning plasma aldosterone concentration (PAC) by approximately 70%. PAC reduction was dose-dependent and associated with a mean placebo-adjusted reduction in systolic blood pressure (BP) of -16.7 mmHg (N=15, p<0.01, 90% CI: -25.5 to -7.9 mmHg) and -12.3 mmHg (N=12, p<0.03, 90% CI: -21.6 to -3.1 mmHg) in subjects with body mass index (BMI) > 30 kg/m 2 receiving 50mg or 100mg QD of lorundrostat, respectively. In contrast, in non-obese individuals, BP reductions were modest and not statistically significant. Salutary BP effects of 100mg QD lorundrostat at week 8 were observed in individuals with normal to high renin (N=30, -11.4 ± 2.5 mmHg) and low renin (N=25, -11.9 ± 2.8 mmHg). Linkage between obesity, HTN and increased aldosterone has been suggested by studies in a mouse model of obesity, hyperleptinemia and HTN. In this model, both leptin receptor blockade and lorundrostat restored normal BP. As anticipated, in the Phase 2 trial, mean serum leptin was elevated at baseline in obese (N=103, 37.8 ± 2.4 ng/mL) v. non-obese (N=88, 21.6 ± 1.9 ng/mL, p<0.001) individuals with uncontrolled HTN and could be a useful biomarker to identify lorundrostat-responsive HTN. MRAs are recommended as fourth-line therapy for resistant HTN. However, MRAs can be associated with hormonal side-effects and stimulate excess aldosterone production that may increase non-genomic signaling, endothelial dysfunction and vessel wall remodeling. Lorundrostat has neither of these liabilities and may be an important new antihypertensive. Renin-independent, leptin- and aldosterone-dependent HTN defines a unique endotype in obese hypertensive individuals. Endotype-targeted therapy may allow early identification, intervention and improved BP control in obese individuals.

Effects of COL1A1 and SYTL2 on inflammatory cell infiltration and poor extracellular matrix remodeling of the vascular wall in thoracic aortic aneurysm.

Thoracic aortic aneurysm (TAA) is a fatal cardiovascular disease, the pathogenesis of which has not yet been clarified. This study aimed to identify and validate the diagnostic markers of TAA to provide a strong theoretical basis for developing new methods to prevent and treat this disease. Gene expression profiles of the GSE9106, GSE26155, and GSE155468 datasets were acquired from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified using the "limma" package in R. Least absolute shrinkage and selection operator (LASSO), support vector machine-recursive feature elimination (SVM-RFE), random forest, and binary logistic regression analyses were used to screen the diagnostic marker genes. Single-sample gene set enrichment analysis (ssGSEA) was used to estimate immune cell infiltration in TAA. A total of 16 DEGs were identified. The enrichment and functional correlation analyses showed that DEGs were mainly associated with inflammatory response pathways and collagen-related diseases. Collagen type I alpha 1 chain ( COL1A1 ) and synaptotagmin like 2 ( SYTL2 ) were identified as diagnostic marker genes with a high diagnostic value for TAA. The expression of COL1A1 and SYTL2 was considerably higher in TAA vascular wall tissues than in the corresponding normal tissues, and there were significant differences in the infiltration of immune cells between TAA and normal vascular wall tissues. Additionally, COL1A1 and SYTL2 expression were associated with the infiltration of immune cells in the vascular wall tissue. Single-cell analysis showed that COL1A1 in TAA was mainly derived from fibroblasts and SYTL2 mainly from cluster of differentiation (CD)8 + T cells. In addition, single-cell analysis indicated that fibroblasts and CD8 + T cells in TAA were significantly higher than those in normal arterial wall tissue. COL1A1 and SYTL2 may serve as diagnostic marker genes for TAA. The upregulation of SYTL2 and COL1A1 may be involved in the inflammatory infiltration of the vessel wall and poor extracellular matrix remodeling, promoting the progression of TAA.

The diagnostic performance of high-resolution magnetic resonance-vessel wall imaging in differentiating atherosclerosis-associated moyamoya vasculopathy from moyamoya disease.

To evaluate the diagnostic performance of high-resolution magnetic resonance-vessel wall imaging (HRMR-VWI) in differentiating moyamoya disease (MMD) from atherosclerosis-associated moyamoya vasculopathy (AS-MMV) and investigate an accurate approach for the differential diagnosis. Adult patients who were diagnosed as MMD or AS-MMV and underwent HRMR-VWI were retrospectively included. The three vessel wall features (outer diameter (OD), remodeling index (RI), and pattern of vessel wall thickening) of middle cerebral artery (MCA) in identifying MMD from AS-MMV were assessed and compared. Furthermore, subgroup analysis stratified by degree of luminal stenosis was performed and the cutoff values of different vessel wall features in differentiating MMD from AS-MMV were also calculated. A total of 265 patients (160 cases of MMD and 105 AS-MMV) were included. Patients with AS-MMV had greater OD and RI and were more likely to exhibit eccentric thickening of vessel wall compared to those with MMD (all p < 0.001). The ROC analysis showed that the AUC value of OD was greater than that of RI (0.912 vs. 0.889, p = 0.007) in differentiating MMD from AS-MMV, and their corresponding cutoff values were 1.77 mm and 0.27, respectively. And the AUC value of pattern of vessel wall thickening was 0.786 in non-occluded patients. With the increase of lumen stenosis, the discrimination power of the three indicators enhanced correspondingly. HRMR-VWI is valuable in distinguishing MMD from AS-MMV. The OD of MCA has better diagnostic performance in differentiating AS-MMV from MMD compared to RI and pattern of vessel wall thickening. The outer diameter of the involved artery proved to be both accurate and convenient in distinguishing atherosclerosis-associated moyamoya vasculopathy from moyamoya disease and may provide a quantitative reference for clinical diagnosis. High-resolution magnetic resonance-vessel wall imaging is valuable in distinguishing atherosclerosis-associated moyamoya vasculopathy from moyamoya disease. Compared to remodeling index and pattern of vessel wall thickening, outer diameter is more accurate in differentiating atherosclerosis-associated moyamoya vasculopathy from moyamoya disease. With the increase of lumen stenosis, the discrimination power of outer diameter, remodeling index, and pattern of vessel wall thickening enhanced correspondingly.

Improving Chronic Venous Disease Management with Micronised Purified Flavonoid Fraction: New Evidence from Clinical Trials to Real Life.

Chronic venous disease (CVD) develops in the microvessels, and is perpetuated by a vicious cycle of inflammation and endothelial activation, structural and functional changes to vessels and valves, and progressive venous hypertension. Data from animal models indicate that micronised purified flavonoid fraction (MPFF) has beneficial effects on a range of pathophysiological processes that contribute to CVD, including inflammation, micro-vessel permeability, valve and vessel wall remodelling, and reflux in microvalves. These effects explain its beneficial effects on the signs and symptoms of CVD, which have been seen across the spectrum of Clinical, Etiological, Anatomical and Pathophysiological (CEAP) categories of CVD severity. This includes patients with symptoms but no detectable anatomical or pathophysiological anomalies (C0s or C1) and patients with varicose veins (C2). In addition to symptomatic improvement, MPFF has been shown to reduce oedema in patients with C3 CVD, resolve skin symptoms in patients with C4 CVD, and accelerate the healing of venous ulcers in patients with C6 CVD. MPFF is highly recommended in international guidelines of CVD management and is the only veno-active drug to receive guideline endorsement for an improvement in patient quality of life.

A multiscale framework for defining homeostasis in distal vascular trees: applications to the pulmonary circulation.

Pulmonary arteries constitute a low-pressure network of vessels, often characterized as a bifurcating tree with heterogeneous vessel mechanics. Understanding the vascular complexity and establishing homeostasis is important to study diseases such as pulmonary arterial hypertension (PAH). The onset and early progression of PAH can be traced to changes in the morphometry and structure of the distal vasculature. Coupling hemodynamics with vessel wall growth and remodeling (G&R) is crucial for understanding pathology at distal vasculature. Accordingly, the goal of this study is to provide a multiscale modeling framework that embeds the essential features of arterial wall constituents coupled with the hemodynamics within an arterial network characterized by an extension of Murray's law. This framework will be used to establish the homeostatic baseline characteristics of a pulmonary arterial tree, including important parameters such as vessel radius, wall thickness and shear stress. To define the vascular homeostasis and hemodynamics in the tree, we consider two timescales: a cardiac cycle and a longer period of vascular adaptations. An iterative homeostatic optimization, which integrates a metabolic cost function minimization, the stress equilibrium, and hemodynamics, is performed at the slow timescale. In the fast timescale, the pulsatile blood flow dynamics is described by a Womersley's deformable wall analytical solution. Illustrative examples for symmetric and asymmetric trees are presented that provide baseline characteristics for the normal pulmonary arterial vasculature. The results are compared with diverse literature data on morphometry, structure, and mechanics of pulmonary arteries. The developed framework demonstrates a potential for advanced parametric studies and future G&R and hemodynamics modeling of PAH.

Association of Plaque Morphology With Stroke Mechanism in Patients With Symptomatic Posterior Circulation ICAD.

Although the main mechanisms of stroke in patients with intracranial atherosclerotic disease (ICAD)-perforating artery occlusion (PAO) and artery-to-artery embolism (AAE)-have been identified and described, relatively little is known about the morphology of the symptomatic plaques and how they differ between these 2 mechanisms. We prospectively recruited patients with acute ischemic stroke in the posterior circulation that was attributable to ICAD. Fifty-one eligible patients were enrolled and underwent magnetic resonance imaging before being assigned to the PAO or AAE group according to probable stroke mechanism. Plaque morphological properties including plaque length, lumen area, outer wall area, plaque burden, plaque surface irregularity, vessel wall remodeling, and plaque enhancement were assessed using high-resolution MRI. Plaque morphological parameters of both PAO and AAE groups were compared using nonparametric tests. A binary logistic regression model was used to identify independent predictors while a receiver operating characteristic curve tested the sensitivity and specificity of the model. Among patients who met the imaging eligibility criteria, 38 (74.5%) had PAO and 13 (25.5%) had AAE. Plaque length was shorter (6.39 interquartile range [IQR, 5.18-7.7]1 mm vs 10.90 [IQR, 8.18-11.85] mm, p < 0.01) in patients with PAO. Plaque burden was lower in PAO group (78.00 [IQR, 71.94-86.35] % vs 86.37 [IQR, 82.24-93.04] %, p = 0.04). The proportion of patients with plaque surface irregularity was higher in patients with AAE than in patients with PAO (19/38, 50.00% vs 12/13, 92.30%, p = 0.008). Plaque length was significantly associated with the PAO mechanism (adjusted OR 0.57, 95% CI, 0.41-0.79). Intracranial atherosclerotic plaque morphology differs between patients with PAO and those with AAE. Plaque with shorter length, lower plaque burden, and regular surface is more likely to cause PAO.

Engineering Smooth Muscle to Understand Extracellular Matrix Remodeling and Vascular Disease

The vascular smooth muscle is vital for regulating blood pressure and maintaining cardiovascular health, and the resident smooth muscle cells (SMCs) in blood vessel walls rely on specific mechanical and biochemical signals to carry out these functions. Any slight change in their surrounding environment causes swift changes in their phenotype and secretory profile, leading to changes in the structure and functionality of vessel walls that cause pathological conditions. To adequately treat vascular diseases, it is essential to understand how SMCs crosstalk with their surrounding extracellular matrix (ECM). Here, we summarize in vivo and traditional in vitro studies of pathological vessel wall remodeling due to the SMC phenotype and, conversely, the SMC behavior in response to key ECM properties. We then analyze how three-dimensional tissue engineering approaches provide opportunities to model SMCs’ response to specific stimuli in the human body. Additionally, we review how applying biomechanical forces and biochemical stimulation, such as pulsatile fluid flow and secreted factors from other cell types, allows us to study disease mechanisms. Overall, we propose that in vitro tissue engineering of human vascular smooth muscle can facilitate a better understanding of relevant cardiovascular diseases using high throughput experiments, thus potentially leading to therapeutics or treatments to be tested in the future.

A Blood Vessel Organoid Model Recapitulating Aspects of Vasculogenesis, Angiogenesis and Vessel Wall Maturation

Blood vessel organoids are an important in vitro model to understand the underlying mechanisms of human blood vessel development and for toxicity testing or high throughput drug screening. Here we present a novel, cost-effective, and easy to manufacture vascular organoid model. To engineer the organoids, a defined number of human induced pluripotent stem cells are seeded in non-adhesive agarose coated wells of a 96-well plate and directed towards a lateral plate mesoderm fate by activation of Wnt and BMP4 signaling. We observe the formation of a circular layer of angioblasts around days 5–6. Induced by VEGF application, CD31+ vascular endothelial cells appear within this vasculogenic zone at approximately day 7 of organoid culture. These cells arrange to form a primitive vascular plexus from which angiogenic sprouting is observed after 10 days of culture. The differentiation outcome is highly reproducible, and the size of organoids is scalable depending on the number of starting cells. We observe that the initial vascular ring forms at the interface between two cell populations. The inner cellular compartment can be distinguished from the outer by the expression of GATA6, a marker of lateral plate mesoderm. Finally, 14-days-old organoids were transplanted on the chorioallantois membrane of chicken embryos resulting in a functional connection of the human vascular network to the chicken circulation. Perfusion of the vessels leads to vessel wall maturation and remodeling as indicated by the formation of a continuous layer of smooth muscle actin expressing cells enwrapping the endothelium. In summary, our organoid model recapitulates human vasculogenesis, angiogenesis as well as vessel wall maturation and therefore represents an easy and cost-effective tool to study all steps of blood vessel development and maturation directly in the human setting without animal experimentation.

WSSNet: Aortic Wall Shear Stress Estimation Using Deep Learning on 4D Flow MRI.

Wall shear stress (WSS) is an important contributor to vessel wall remodeling and atherosclerosis. However, image-based WSS estimation from 4D Flow MRI underestimates true WSS values, and the accuracy is dependent on spatial resolution, which is limited in 4D Flow MRI. To address this, we present a deep learning algorithm (WSSNet) to estimate WSS trained on aortic computational fluid dynamics (CFD) simulations. The 3D CFD velocity and coordinate point clouds were resampled into a 2D template of 48 × 93 points at two inward distances (randomly varied from 0.3 to 2.0 mm) from the vessel surface (“velocity sheets”). The algorithm was trained on 37 patient-specific geometries and velocity sheets. Results from 6 validation and test cases showed high accuracy against CFD WSS (mean absolute error 0.55 ± 0.60 Pa, relative error 4.34 ± 4.14%, 0.92 ± 0.05 Pearson correlation) and noisy synthetic 4D Flow MRI at 2.4 mm resolution (mean absolute error 0.99 ± 0.91 Pa, relative error 7.13 ± 6.27%, and 0.79 ± 0.10 Pearson correlation). Furthermore, the method was applied on in vivo 4D Flow MRI cases, effectively estimating WSS from standard clinical images. Compared with the existing parabolic fitting method, WSSNet estimates showed 2–3 × higher values, closer to CFD, and a Pearson correlation of 0.68 ± 0.12. This approach, considering both geometric and velocity information from the image, is capable of estimating spatiotemporal WSS with varying image resolution, and is more accurate than existing methods while still preserving the correct WSS pattern distribution.

Hsa_circWDR37_016 Regulates Hypoxia-Induced Proliferation of Pulmonary Arterial Smooth Muscle Cells.

Pulmonary arterial hypertension (PAH) is characterized by abnormal remodeling of pulmonary vessel walls caused by excessive pulmonary arterial smooth muscle cell (PASMC) proliferation. Our previous clinical studies have demonstrated the importance of the downregulated circRNA in PAH. However, the role of upregulated circRNAs is still elusive. Here, we identified the upregulated circRNA in PAH patients, hsa_circWDR37_016 (circWDR37), as a key regulator of hypoxic proliferative disorder of pulmonary arterial smooth muscle cells (PASMCs). Quantitative real-time PCR (qRT-PCR) analysis validated that exposure to hypoxia markedly increased the circWDR37 level in cultured human PASMCs. As evidenced by flow cytometry, 5-ethynyl-2′-deoxyuridine (EdU) incorporation, wound healing, and Tunel assay, silencing of endogenous circWDR37 attenuated proliferation and cell-cycle progression in hypoxia-exposed human PASMCs in vitro. Furthermore, bioinformatics and Luciferase assay showed that circWDR37 directly sponged hsa-miR-138-5p (miR-138) and was involved in the immunoregulatory and inflammatory processes of PAH. Together, these studies suggested new insights into circRNA regulated the pathology of PAH, providing a new potential therapeutic target for PAH treatment.

Acetylsalicylic Acid Reduces Passive Aortic Wall Stiffness and Cardiovascular Remodelling in a Mouse Model of Advanced Atherosclerosis.

Acetylsalicylic acid (ASA) is widely used in secondary prevention of cardiovascular (CV) disease, mainly because of its antithrombotic effects. Here, we investigated whether ASA can prevent the progression of vessel wall remodelling, atherosclerosis, and CV complications in apolipoprotein E deficient (ApoE−/−) mice, a model of stable atherosclerosis, and in ApoE−/− mice with a mutation in the fibrillin-1 gene (Fbn1C1039G+/−), which is a model of elastic fibre fragmentation, accompanied by exacerbated unstable atherosclerosis. Female ApoE−/− and ApoE−/−Fbn1C1039G+/− mice were fed a Western diet (WD). At 10 weeks of WD, the mice were randomly divided into four groups, receiving either ASA 5 mg/kg/day in the drinking water (ApoE−/− (n = 14), ApoE−/−Fbn1C1039G+/− (n = 19)) or plain drinking water (ApoE−/− (n = 15), ApoE−/−Fbn1C1039G+/− (n = 21)) for 15 weeks. ApoE−/−Fbn1C1039G+/− mice showed an increased neutrophil–lymphocyte ratio (NLR) compared to ApoE−/− mice, and this effect was normalised by ASA. In the proximal ascending aorta wall, ASA-treated ApoE−/−Fbn1C1039G+/− mice showed less p-SMAD2/3 positive nuclei, a lower collagen percentage and an increased elastin/collagen ratio, consistent with the values measured in ApoE−/− mice. ASA did not affect plaque progression, incidence of myocardial infarction and survival of ApoE−/−Fbn1C1039G+/− mice, but systolic blood pressure, cardiac fibrosis and hypertrophy were reduced. In conclusion, ASA normalises the NLR, passive wall stiffness and cardiac remodelling in ApoE−/−Fbn1C1039G+/− mice to levels observed in ApoE−/− mice, indicating additional therapeutic benefits of ASA beyond its classical use.

Dissecting Abdominal Aortic Aneurysm Is Aggravated by Genetic Inactivation of LIGHT (TNFSF14)

Abdominal aortic aneurysm (AAA), is a complex disorder characterized by vascular vessel wall remodeling. LIGHT (TNFSF14) is a proinflammatory cytokine associated with vascular disease. In the present study, the impact of genetic inactivation of Light was investigated in dissecting AAA induced by angiotensin II (AngII) in the Apolipoprotein E-deficient (Apoe−/−) mice. Studies in aortic human (ah) vascular smooth muscle cells (VSMC) to study potential translation to human pathology were also performed. AngII-treated Apoe−/−Light−/− mice displayed increased abdominal aorta maximum diameter and AAA severity compared with Apoe−/− mice. Notably, reduced smooth muscle α-actin+ area and Acta2 and Col1a1 gene expression were observed in AAA from Apoe−/−Light−/− mice, suggesting a loss of VSMC contractile phenotype compared with controls. Decreased Opn and augmented Sox9 expression, which are associated with detrimental and non-contractile osteochondrogenic VSMC phenotypes, were also seen in AngII-treated Apoe−/−Light−/− mouse AAA. Consistent with a role of LIGHT preserving VSMC contractile characteristics, LIGHT-treatment of ahVSMCs diminished the expression of SOX9 and of the pluripotency marker CKIT. These effects were partly mediated through lymphotoxin β receptor (LTβR) as the silencing of its gene ablated LIGHT effects on ahVSMCs. These studies suggest a protective role of LIGHT through mechanisms that prevent VSMC trans-differentiation in an LTβR-dependent manner.