Human Carotid Artery Research Articles

Photothermal optical coherence microscopy for studying lipid architecture in human carotid arteries

Photothermal optical coherence microscopy (PT-OCM) combines the high-resolution, label-free morphological imaging of OCM with the ability to discriminate tissue composition through phase-sensitive photothermal imaging. In this study, we perform 2D imaging of human carotid endarterectomies to spectrally determine lipid distribution, with verification via histologically stained samples. The structural information from OCM is combined with the spectral information gained from measuring the resulting sample surface displacement from thermoelastic expansion, following light irradiation. PT-OCM is thus demonstrated as a potential tool in the investigation of atherosclerotic plaque lipids, contributing towards the understanding of plaque instability.

CFD Analysis of Non-Newtonian Blood Flow through Human Carotid Artery Bifurcation: Carotid Sinus Susceptible to Atherosclerosis

CFD Analysis of Non-Newtonian Blood Flow through Human Carotid Artery Bifurcation: Carotid Sinus Susceptible to Atherosclerosis

Leukemia Inhibitory Factor Receptor inhibition by EC359 reduces atherosclerotic stenosis grade in Ldlr-/- mice

Cytokines are involved in all stages of atherosclerosis, generally contributing to disease progression. Previously, members of the IL-6 cytokine family, such as Interleukin-6, oncostatin M, and cardiotrophin-1, have been extensively studied in atherosclerosis. However, the role of leukemia inhibitory factor (LIF), member of the IL-6 family, and its receptor (LIFR), remains to be further elucidated. Therefore, the aim of this study is to provide insight in LIF receptor signalling in atherosclerosis development.Single-cell RNA sequencing analysis of human carotid artery plaques revealed that mast cells highly express LIF, whereas LIFR was specifically expressed on activated endothelial cells. A similar expression pattern of Lifr was observed in mouse atherosclerotic plaques. Next, female Western-type diet fed Ldlr-/- mice were treated with LIF receptor inhibitor EC359 (5 mg/kg s.c., n=15) or control solvent (n=15) three times per week for eight weeks. Stenosis grade was reduced in the aortic root of EC359 treated mice compared to control mice, but treatment did not affect plaque composition. Serum cholesterol levels were significantly reduced in EC359 treated mice, likely attributed to a reduction in VLDL cholesterol levels. Furthermore, LIF receptor inhibition reduced Pecam1 and Vcam1 expression in the aorta. Consequently, immune cell infiltration was reduced in aortic plaques of EC359 treated mice compared to control mice.Conclusively, we demonstrated that LIF receptor is a potential therapeutic target in atherosclerosis by reducing plaque size, attributed to lower serum cholesterol levels, reduced endothelial activation and less immune cell infiltration in the plaque.

Experimental evidence on colchicine's mode of action in human carotid artery plaques

Abstract Background and aims Atherosclerosis driven by inflammation is a major cause of cardiovascular events. Recent clinical trials have demonstrated the therapeutic potential of anti-inflammatory treatments. Consequently, colchicine is recommended in current guidelines as a second-line therapy for secondary prevention, although the drug's mechanism of action is not fully understood. Methods To this end, we performed a multiomic study of the effect of colchicine on human carotid plaques. Sections from endarterectomy specimens were exposed ex vivo to colchicine at concentrations of 2 ng/ml and 10 ng/ml for 24 hours and compared with untreated segments of the same plaque. Changes in gene expression were analyzed by RNA sequencing, and plaque secretomes were subjected to proteomic analysis by mass spectrometry. In situ cell proliferation was examined histologically. Results Our data suggest that colchicine primarily suppresses neutrophil and platelet degranulation, collagen degradation, and macrophage proliferation in atheromatous plaques in a dose-dependent manner, while stimulating myofibroblast activation. Conclusion Our study demonstrates multifactorial pathways by which colchicine, the first anti-inflammatory drug recommended by cardiovascular guidelines, acts on human atherosclerotic lesions. Targeting neutrophil and platelet degranulation, collagen degradation and macrophage proliferation could provide significant therapeutic benefit in atherosclerotic cardiovascular disease without the adverse side effects of colchicine.

Association of ethanolamine desaturase TMEM189-plasmalogen axis with the stability of atherosclerotic plaque and cardiovascular events after acute coronary syndrome

Abstract Background Patients with acute coronary syndrome (ACS) are still at high risk of recurring major adverse cardiovascular events (MACE). Disorders of lipid metabolism play an important role in the pathogenesis and progression of ACS. However, whether there are lipid components that can play an early warning role on the recurrence of MACE in patients with ACS and its potential mechanism is not yet known. Purpose To explore the changes of lipid profile before recurrent MACE in ACS patients, screen lipid molecules related to recurrent MACE, and explore their effects on pathological changes of atherosclerotic plaque. Methods We selected 44 Chinese ACS patients from the ‘Peking and Rotterdam on Mission to Reduce Coronary Artery Disease’ (PRoMISS) study. Among them, patients with recurrent MACE within 1 year after first onset of ACS were defined as MACE group, and the control group was recruited through 1:1 matching. The lipid profile of patients was analyzed by liquid chromatography-mass spectrometry. The effects of the screened potential lipid biomarkers and their synthesis enzymes were evaluated by real-time PCR, Western blot, IHC staining and ELISA. The enzyme knockout mice and ApoE knockout mice were hybridized and bred to obtain double gene knockout mice to determine whether the enzyme deficiency affects atherosclerotic plaque. Results Lipomic analysis showed that in the MACE group, plasmalogens and their 12 subtypes continued to decrease three months before the MACE recurrence. The most critical ethanolamine desaturase in the synthesis pathway of plasmalogen, transmembrane protein 189 (TMEM189) was also significantly lower in the MACE group than in the control group, and the level of TMEM189 was positively correlated with plasmalogen. Analysis of single-cell RNA sequencing results in human carotid artery plaques shows that TMEM189 is enriched in endothelial cells and smooth muscle cells (VSMC). In VSMC, treatment with oxLDL reduced TMEM189 expression. Overexpression of TMEM189 significantly improved oxLDL induced reduction in collagen synthesis, expression of alpha-smooth muscle actin (alpha-SMA) and smooth muscle protein 22 (SM22). Overexpression of TMEM189 in VSMC, significantly reduced the content of plasmalogens in the cells. After 12 weeks of feeding with high-fat and high-cholesterol diet, it was found that the content of smooth muscle cells and vulnerability index in the aortic plaque in TMEM189 -/-ApoE -/- mice were significantly decreased than in ApoE -/- mice. Conclusions Before the recurrence of MACE in ACS patients, the synthesis pathway of plasmalogen was gradually damaged, and the reduction of plasmalogen was a potential marker for predicting the recurrence of MACE in ACS patients. The deficiency of TMEM189 - plasmalogen axis aggravates atherosclerosis, it can regulate the phenotype transformation of smooth muscle cells, inhibit their collagen synthesis, and thus affect plaque stability.

Metagenomic analysis of atheroma plaques for identification of microorganisms indicates presence of Toxoplasma gondii as a possible etiological agent

BackgroundCardiovascular diseases (CVDs) are the leading cause of death worldwide. Vital organs like the heart are affected by the occlusion of blood vessels due to atherosclerotic plaque formation. However, the role of infectious agents has always been an essential subject of investigation. This study investigated the presence of microorganisms, including nanobacteria, in atherosclerotic plaques removed from human carotid arteries by microbiological and metagenomic examination. MethodsAtheroma plaque samples were obtained from 20 patients with carotid artery stenosis who had atherectomy by surgery or percutaneous intervention. Nanobacteria were grown by culturing homogenates of the atheroma plaques. Whole genome sequencing was done for samples. Because of the high percentage of Toxoplasma gondii (T. gondii) DNA, PCR investigation was applied to detect T. gondii DNA in the samples. ResultsA molecular analysis of nanobacteria revealed them to be made of human proteins, supporting the theory that they are not living organisms. According to sequencing results, samples showed that more than 50 % of the metagenomic sequences belonged to Toxoplasma gondii. PCR investigation indicated that T. gondii DNA was positive in 8 (40 %) of 20 plaques. ConclusionsFurther evidence regarding the role of T. gondii in the etiology of plaque formation may help determine the strategy for prevention and treatment of infections in preventing atheroma plaque formation in the future.

Adaptive weight determination schemes in angle and sub-band compounding for ultrasonic beamforming

Abstract We have proposed the Adaptive Sub-Band Compound (A-SBC) method, which uses subbands of different frequencies to improve the resolution by adaptive compounding. A-SBC effectively suppresses the sidelobe level by mainly utilizing the principle that the phases of subbands of different frequencies are inconsistent off-axis. There are many specific methods that can realize A-SBC. In this study, we propose three additional methods based on a previous application of A-SBC to multi-angle plane-wave beamforming. We evaluate these four methods through simulation and human carotid artery experiments.

Potential of diagnostic electron microscopy of calcification, pathological neovascularization and elastolysis in combination with phenotyping of cell populations in large arteries

Aim. To determine the potential of diagnostic electron microscopy of intraplaque processes (severity of lipid damage, fibrous cap thickness and condition, severity of pathological neovascularization, presence, nature and severity of calcification, ratio and distribution of various cell populations).Material and methods. The study objects were plaques removed during endar­terectomy from the human carotid artery and segments of the human internal mammary artery removed during coronary bypass surgery. Whole specimens were subjected to chemical fixation, staining with heavy metal salts, embedding in epoxy resin followed by layer-by-layer grinding, polishing, contrasting, visualization using back-scattered electron scanning electron microscopy and three-dimensional reconstruction with color mapping (modified EM-BSEM).Results. The use of a modified EM-BSEM made it possible to: 1) visualize the fibrous cap thickness and assess the extracellular matrix; 2) analyze the neointimal lipid distribution; 3) perform three-dimensional reconstruction and analyze the microenvironment of calcifications of various sizes; 4) visualize endothelial cells, defects in interendothelial contacts and the basement membrane of neointimal capillaries with their subsequent three-dimensional reconstruction; 5) perform an analysis of age-dependent defects in the basement membrane and internal elastic membrane of the internal mammary artery. The resolution of the obtained images was significantly superior to intravascular imaging methods (intravascular ultrasound and optical coherence tomography), allowing additional assessment of capillary fluidity, the degree of calcification encapsulation and the condition of elastic fibers. Three-dimensional reconstruction of calcifications, neointimal capillaries and elastic fibers made it possible to assess their spatial density and heterogeneity. Simultaneously with the identification and assessment of these histological structures, objective phenotyping of cell populations was performed, which made it possible to isolate macrophages and foam cells, vascular smooth muscle cells, fibroblasts and endothelial cells in atherosclerotic plaques and automatically identify them through color mapping determined by their electronic contrast distribution signatures.Conclusion. The modified EM-BSEM method allows for universal electron microscopic diagnosis of atherosclerotic and elastolytic lesions of large arteries with high information content about vascular remodeling and high accuracy. Electronic contrast distribution signatures unique for each cell population indicate the possibility of their automated phenotyping using specialized neural network algorithms.

A modified sidelobe blanking beamforming method for ultrasound plane wave imaging.

In this paper, an ultrasound beamforming method for plane wave (PW) imaging based on modified sidelobe blanking (MSLB) is proposed to improve image resolution and contrast ratio (CR). In this framework, PWs from various angles were designed to create main and auxiliary beamformer signals. Specifically, the PW signals from all angles were first coherently combined to serve as the main beamformer output signals. To prevent excessive clutter and noise, output signals in the main beamformer were weighted by the generalized coherence factor. Subsequently, the PW signals were split into positive and negative angles to perform a subtraction, creating the auxiliary beamformer. Finally, signals in the main beamformer were compared with the signals in the auxiliary beamformer point by point to further eliminate the noises and clutters. Compared with the delay and sum, full width at half maximum of the MSLB for point targets was reduced by an average of 54.17% and 51.65% in simulations and experiments, respectively; and the corresponding CR was improved by 55.38% and 18.40% on average. The MSLB method provided better imaging quality in human carotid arteries. In conclusion, the proposed method can effectively improve image resolution and CR with low computational complexity.

Near-infrared multispectral photoacoustic analysis of lipids and intraplaque hemorrhage in human carotid artery atherosclerosis

Spectral photoacoustic imaging in combination with unmixing techniques may be applied to retrieve information about high-risk features present in atherosclerotic plaques, possibly providing prognostic insights into future stroke events. We present the photoacoustic spectral contrast found in 12 systematically scanned advanced atherosclerotic plaques in the near-infrared wavelength range (850–1250 nm). The main absorbers are lipid, water, and hemoglobin, with the highest photoacoustic intensities at the lipid’s second overtone at 1190 and 1210 nm. Linear unmixing resulted in visualizing regions with high lipid and hemoglobin absorption, corresponding to the histological presence of lipid and intraplaque hemorrhage. A non-negative matrix factorization approach reveals differences in lipid spectral contrast, providing potential insights into the vulnerability of atherosclerotic plaque. These results provide a reference for future, more complex, in vivo photoacoustic imaging of carotid artery atherosclerosis, potentially contributing to assessing the risk of future events and treatment decision.

Genome-scale metabolic network of human carotid plaque reveals the pivotal role of glutamine/glutamate metabolism in macrophage modulating plaque inflammation and vulnerability

BackgroundMetabolism is increasingly recognized as a key regulator of the function and phenotype of the primary cellular constituents of the atherosclerotic vascular wall, including endothelial cells, smooth muscle cells, and inflammatory cells. However, a comprehensive analysis of metabolic changes associated with the transition of plaque from a stable to a hemorrhaged phenotype is lacking.MethodsIn this study, we integrated two large mRNA expression and protein abundance datasets (BIKE, n = 126; MaasHPS, n = 43) from human atherosclerotic carotid artery plaque to reconstruct a genome-scale metabolic network (GEM). Next, the GEM findings were linked to metabolomics data from MaasHPS, providing a comprehensive overview of metabolic changes in human plaque.ResultsOur study identified significant changes in lipid, cholesterol, and inositol metabolism, along with altered lysosomal lytic activity and increased inflammatory activity, in unstable plaques with intraplaque hemorrhage (IPH+) compared to non-hemorrhaged (IPH−) plaques. Moreover, topological analysis of this network model revealed that the conversion of glutamine to glutamate and their flux between the cytoplasm and mitochondria were notably compromised in hemorrhaged plaques, with a significant reduction in overall glutamate levels in IPH+ plaques. Additionally, reduced glutamate availability was associated with an increased presence of macrophages and a pro-inflammatory phenotype in IPH+ plaques, suggesting an inflammation-prone microenvironment.ConclusionsThis study is the first to establish a robust and comprehensive GEM for atherosclerotic plaque, providing a valuable resource for understanding plaque metabolism. The utility of this GEM was illustrated by its ability to reliably predict dysregulation in the cholesterol hydroxylation, inositol metabolism, and the glutamine/glutamate pathway in rupture-prone hemorrhaged plaques, a finding that may pave the way to new diagnostic or therapeutic measures.

Ultrasound Speckle Decorrelation Analysis-Based Velocimetry for 3D-Velocity-Components Measurement Using a 1D Transducer Array.

Ultrasound velocimetry has been widely used for blood flow imaging. However, the flow measurements are constrained to resolve the in-plane 2D flow components when using a 1D transducer array. In this work, an ultrasound speckle decorrelation analysis-based velocimetry (3C-vUS) is proposed for 3D velocity components measurement using a 1D transducer array. The 3C-vUS theory is first derived and validated with numerical simulations and phantom experiments. The in vivo testing results show that 3C-vUS can accurately measure the blood flow 3D-velocity-components of the human carotid artery at arbitrary probe-to-vessel angles throughout the cardiac cycle. With such capability, the 3C-vUS will alleviate the requirement of operators and promote disease screening for blood flow-related disorders.

Arterial Distension Monitoring Scheme Using FPGA-Based Inference Machine in Ultrasound Scanner Circuit System.

This paper presents an arterial distension monitoring scheme using a field-programmable gate array (FPGA)-based inference machine in an ultrasound scanner circuit system. An arterial distension monitoring requires a precise positioning of an ultrasound probe on an artery as a prerequisite. The proposed arterial distension monitoring scheme is based on a finite state machine that incorporates sequential support vector machines (SVMs) to assist in both coarse and fine adjustments of probe position. The SVMs sequentially perform recognitions of ultrasonic A-mode echo pattern for a human carotid artery. By employing sequential SVMs in combination with convolution and average pooling, the number of features for the inference machine is significantly reduced, resulting in less utilization of hardware resources in FPGA. The proposed arterial distension monitoring scheme was implemented in an FPGA (Artix7) with a resource utilization percentage less than 9.3%. To demonstrate the proposed scheme, we implemented a customized ultrasound scanner consisting of a single-element transducer, an FPGA, and analog interface circuits with discrete chips. In measurements, we set virtual coordinates on a human neck for 9 human subjects. The achieved accuracy of probe positioning inference is 88%, and the Pearson coefficient (r) of arterial distension estimation is 0.838.

Red blood cell-derived extracellular vesicles from type 2 diabetes patients induce endothelial dysfunction through a mechanism involving arginase 1

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Foundation for Geriatric Diseases Karolinska Institutet (2023-01860). Swedish Heart and Lung Foundation (20220210) Background The mechanisms driving the development of cardiovascular injury in type 2 diabetes (T2D) remain incompletely understood. We have recently demonstrated that red blood cells (RBCs) from patients with T2D (T2D-RBCs) act as mediators of endothelial dysfunction through the upregulation of arginase 1 and attenuation of nitric oxide bioavailability. However, the underlying mechanisms of this interaction remain unknown. It is increasingly clear that extracellular vesicles (EVs) are actively secreted by practically all cell types, including RBCs, and represent a novel mechanism of intercellular communication. However, the involvement of RBC-derived EVs in the development of endothelial dysfunction in T2D remains to be elucidated. Purpose To test the hypothesis that EVs are secreted by RBCs and transfer signalling to induce endothelial dysfunction in T2D through arginase 1. Methods EVs released from T2D-RBCs (T2D-RBCs EVs) and RBCs from age-matched healthy controls (H-RBCs EVs) were isolated using sequential ultracentrifugation or a membrane affinity column, co-incubated with mouse aortae to evaluate endothelium-dependent relaxation (EDR), and with human carotid artery endothelial cells (HCtAEC) to study the EV uptake and alteration in gene expression. EVs were characterized based on morphology, size and particle number, uptake in endothelial cells, and arginase 1 content. Functional involvement of EV uptake and arginase were investigated using pharmacological interventions. Arginase 1 was measured in EVs, HCtAEC, and mouse aortae after co-incubation with H-RBCs EVs and T2D-RBCs EVs. Results The uptake of T2D-RBCs EVs by endothelial cells was greater than that of EVs from H-RBCs (Fig. 1A, B) despite the reduced formation of EVs by T2D-RBCs (Fig. 1C). T2D-RBCs EVs significantly impaired EDR (Fig. 1D), and this impairment was prevented by inhibiting uptake of EVs with heparin (Fig. 1E). Arginase 1 was detected in RBC-derived EVs (Fig. 2A), and endothelial function was rescued by blocking arginase activity in EVs by the arginase inhibitor 2(S)-amino-6-boronohexanoic acid (ABH; Fig. 2B). Immunohistochemical staining revealed upregulation of arginase 1 in the vasculature following incubation with T2D-RBCs EVs (Fig. 2C, D). Additionally, co-incubation of HCtAEC and EVs derived from T2D-RBCs significantly increased endothelial cell arginase 1 (Fig. 2E, F). Administration of ABH to the aortae following the co-incubation also attenuated the impairment of EDR induced by T2D-RBCs EVs, suggesting the involvement of vascular arginase 1 (Fig. 2G). Conclusion T2D-RBCs EVs induce endothelial dysfunction. In addition to increased uptake of EVs in endothelial cells, the signalling behind this effect of EVs is mediated by arginase 1 to induce endothelial dysfunction. These results shed new important light on the mechanism underlying vascular injury mediated by RBCs in T2D.

Leukemia inhibitory factor receptor inhibition reduces stenosis grade and total serum cholesterol levels in a mouse model for atherosclerosis

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Dutch Heart Foundation Atherosclerosis is characterized by the accumulation of lipids and immune cells in the arterial wall and it is the main underlying pathology causing cardiovascular diseases (CVD). Cytokines are involved in all stages of atherosclerosis and most cytokines contribute to disease progression. For instance, IL-6 cytokine family members, such as IL-6, oncostatin-M and cardiotrophin-1, are closely related to CVDs. However, the role of leukemia inhibitory factor (LIF), a member of the IL-6 cytokine family, and its receptor (LIFR) in atherosclerosis remains unknown. Therefore, the aim of this study is to assess the contribution of LIFR signaling to atherosclerosis development by systemically inhibiting LIFR in an atherosclerotic mouse model. First, the expression of LIF and LIFR was examined using single-cell RNA sequencing data of human carotid artery plaques. Mast cells highly and exclusively express LIF, whereas LIFR was specifically expressed by activated endothelial cells. To validate LIFR signaling in vivo, female western-type diet fed Ldlr-/- mice were treated with LIFR inhibitor EC359 (5 mg/kg s.c., n=15) or control solvent (n=15) three times per week for eight weeks. During the experiment, weights of the mice did not differ between groups, whereas total serum cholesterol levels were significantly reduced in EC359 treated mice (p=0.03). In particular, EC359 treatment reduced VLDL levels. Additionally, EC359 treatment significantly reduced Sr1, Abca1 and Lrp1 expression in the liver, suggesting an altered lipid metabolism in EC359 treated mice. Furthermore, LIFR inhibition affected innate immunity, both systemically and locally in the plaque. Neutrophil numbers were significantly increased in the circulation (ctrl 18.7±1.7%; EC359 28.0±2.0%; p=0.002) and aortic plaques (ctrl 3.9±0.8%; EC359 9.9±1.9%; p=0.003) of mice treated with EC359 compared to control mice. Moreover, LIFR inhibition affected circulating monocytes resulting in less inflammatory monocytes. The adaptive immune cells, such as T and B cells, remained largely unaffected. Collectively, the reduction of serum total cholesterol and increase in neutrophil numbers in EC359 treated mice resulted in a trend towards reduced atherosclerotic stenosis grade compared to control mice (39.8±1.4% versus 34.9±1.9%; p=0.054), but it did not affect plaque collagen and monocyte/macrophage content in the aortic root. Conclusively, LIFR signaling inhibition reduces atherosclerotic stenosis grade, lowers plasma total cholesterol levels and affects innate immunity.

Abstract 2079: Single-cell And Spatially Resolved Transcriptome Analysis Reveals A Novel Lncrna Regulator Of Human Atherosclerosis

Cardiovascular diseases, such as atherosclerosis, are the major cause of death in Western societies. Still, molecular mechanisms of plaque destabilization remain unclear. Vascular Smooth Muscle Cells (VSMCs) are the most abundant cell type in atherosclerotic lesions. These cells keep their plasticity also with disease progression and are, therefore, an ideal target cell type for potential therapies. Long non-coding RNAs (lncRNAs) are one example of highly cell type- and disease-state-specific novel molecular modulators. We utilized combined total (bulk) RNA and single cell (sc) RNA sequencing of advanced human carotid artery lesions (patients who underwent carotid endarterectomy in our vascular surgery clinic) to discover novel regulators. Additionally, we performed hybridization-based RNA in situ sequencing (HybRISS, Xenium) to indicate where these genes are located within the plaques. We also performed scSeq in our inducible carotid artery plaque rupture mice ( ApoE-/- ). In vivo and in vitro modulation (KD; knock-down) of the newly identified lncRNA DLX6-AS1 ( D istal- L ess Homeobo x 6 A nti s ense 1 ) using Antisense LNA (Locked nucleic acid) GapmeRs is performed in this mouse model as well as in primary human VSMC culture. DLX6-AS1 shows a highly specific expression pattern in a distinct sub-cluster of VSMCs, as well as a striking location within human atherosclerotic lesions shown by spatial transcriptomics in advanced plaques. DLX6-AS1 is mainly expressed in the nucleus of cells, and KD of this lncRNA leads to changes in VSMC behavior in vitro and in vivo . The KD also has only little effect on the other genes of this locus, DLX6 and DLX5 ( D istal- L ess Homeobo x 6 and 5 ) We found Dlx6os1 ( D istal- l ess homeobo x 6, o pposite s trand 1 ) in our scRNA-seq dataset of the inducible carotid artery plaque rupture mice ( ApoE-/- ) where the KD leads to an increased plaque rupture rate. Taken together, our datasets, methods, and animal models demonstrate that utilizing bulk- and scRNA-seq data, together with spatially resolved sequencing methods, are powerful tools to identify and characterize novel lncRNA regulators that can facilitate fate decisions in VSMCs in atherosclerosis. DLX6-AS1 is one of these novel regulators and will be further analyzed in vivo and in vitro .

Abstract 1127: Erythrocyte Derived Extracellular Vesicles From Patients With Type 2 Diabetes Induce Endothelial Dysfunction Through Increased Vascular Oxidative Stress

Background: Red blood cells (RBCs) from patients with T2D (T2D-RBCs) induce endothelial dysfunction, but the mechanisms remain unclear. It is increasingly clear that extracellular vesicles (EVs) are actively secreted by RBCs and represent a novel mechanism of intercellular communication. However, the functional role of T2D-RBCs EVs in communication between RBCs and the cardiovascular system remains unknown. Purpose: This study aims to investigate whether EVs induce endothelial dysfunction in T2D and, if this is mediated via increased vascular oxidative stress. Material and Methods: EVs derived from T2D-RBCs and healthy RBCs (H-RBCs) were isolated using a membrane affinity column and co-incubated with wild-type mouse aortas for evaluation of the endothelium-dependent relaxation (EDR) using the wire myograph in the presence or absence of non-selective reactive oxygen species scavenger N-acetyl cysteine (NAC; 100 μM) applied to the aortas following the 18h EV incubation. The levels of the oxidative stress marker 4-hydroxynonenal (4-HNE) were quantified by immunohistochemistry in mouse aortas incubated with EVs. Additionally, T2D-RBCs EVs and H-RBCs EVs were co-incubated with human carotid artery endothelial cells (HCtAEC) for 8h and 24h to study the effects of EVs on vascular mRNA expression levels of eNOS, NOX1, and NOX4. Results: T2D-RBCs EVs but not H-RBCs EVs impaired EDR in aortas isolated from mice ( Fig. 1A ). This impairment was reversed by inhibiting oxidative stress in the vessel by NAC ( Fig. 1B ). Immunohistochemistry showed a significant increase in 4-HNE levels in aortas incubated with T2D-RBCs EVs ( Fig. 1C, D ). The T2D-RBCs EVs also induced a significant increase in NOX4 mRNA levels in HCtAEC after 24h but not 8h ( Fig. 1E, F ). However, T2D-RBCs EVs did not affect eNOS or NOX1 in endothelial cells. Conclusion: EVs derived from T2D-RBCs induce endothelial dysfunction through increased vascular oxidative stress.

Computational simulation of the effects of blood flow velocity on atherosclerosis progression in a human carotid artery

Background Atherosclerosis is a build-up of low-density lipoproteins (LDL) in the channels of blood vessels. This occludes the vessels and, occurring in the carotid arteries, portends conditions that favour stroke. This work is an attempt to mathematically represent the physiological process of atherosclerosis caused by plaques on the walls of the human arteries. Aim Provide insight into the effect of blood flow velocity on wall shear stress and its implications on atherosclerosis progression in a human carotid artery via computational simulation. Methods The effect of blood velocity on plaque growth and progression is simulated using COMSOL multi-physics. The human carotid was modeled in 2-D with Stokes law for model flow. The simulation began with a plaque-free vessel with velocities of 30 m/s – 125 m/s. Results Results showed that the rate of plaque initiation dropped as the blood velocity increased from 30 m/s to 125 m/s; higher inlet velocities gave lower plaque growth; the highest degree of 30% stenosis was recorded at a blood velocity of 30 m/s. Plaque height significantly affects the Plaque wall Stress, PWS, and its distribution around the plaque and arterial wall; higher plaque heights experience higher velocity distribution around the plaque, causing a higher force associated with blood flow around the plaque, resulting in higher compression stress. More compressional stresses are localized around the root, which would encourage growth as well as possible rupture at higher velocities. These ruptured plaques potentially narrow or block the arteries and prevent blood flow. This is atherosclerosis and can lead to a heart attack. Conclusion Results from this study can find significant use in the understanding, management, and treatment of atherosclerosis since the regulation of blood velocity and pressure plays a major role in the progress of atherosclerosis in the carotid artery which raises the risk of stroke.

Estimation of local arterial stiffness using non-invasive flow measurements: a study on a stenosed carotid artery

Arterial stiffness is a well-established independent prognostic bio-marker in the human cardiovascular system (CVS). Despite its value as a predictive bio-marker, the inclusion of vascular stiffness into standard clinical procedures or guidelines is limited. This has come about as a result of the abundance of tools created to estimate and evaluate local arterial stiffness in people. This study employs a non-invasive technique to measure local arterial stiffness in the human carotid arteries using proximal flow measurements. Within this work, a viscoelastic lumped-parameter (0D) model of the carotid arteries is developed in complement with the non-invasive flow measurements obtained from the Doppler ultrasound. Further, concepts of sensitivity analysis and parameter estimation are applied to estimate arterial stiffness using the flow measurement taken at the common carotid artery (CCA). After the successful estimation of arterial stiffness in CCA, results show good agreement between model simulations and actual measurement.

Investigation on vector Doppler method for carotid artery wall with focused transmit beams produced from a cross-shaped probe

Conventional methods for estimating 1D or 2D velocities were developed for the dynamic measurement of carotid walls. However, a carotid wall moves in 3D due to a heart pulsation, and the wall motion velocity in the longitudinal-axis cross-section is affected by out-of-plane displacements that cannot be measured with a 1D array probe. To estimate the out-of-plane displacement, we proposed the cross-shaped probe. The cross-shaped probe can estimate 3D velocity vector with 256 transmit-receive channels. Single or multiple focused beams were transmitted by the main array of the cross-shaped probe, and the RF signals received all the elements were used for 3D velocity vector estimation based on the multi-angle Doppler method. Numerical simulations and basic experiments showed that out-of-plane displacements in the longitudinal-axis cross section can be estimated. Furthermore, the in vivo experiments on a human common carotid artery showed that arterial wall motion during a cardiac cycle can be measured.