Smooth muscle cells clonally expand in a murine carotid allograft model complicated by immune reactions to reporter transgenes.

Background And Aims: Most experimental studies of allograft vasculopathy (AV) have relied on transplantation between major histocompatibility complex-mismatched inbred mouse strains, but this leads to the complete eradication of donor smooth muscle cells (SMCs) and lesions formed by recipient cells. This is unlike human AV which is thought to form mainly by donor SMCs. Here, we studied sources of neointimal cells in a minor histocompatibility antigen-mismatched AV model by combining male-to-female orthotopic carotid transplantations and lineage tracing by SMC-specific expression of fluorescent proteins.

Predicting the presence of coronary plaques featuring high-risk characteristics using polygenic risk scores and targeted proteomics in patients with suspected coronary artery disease.

Background: The presence of coronary plaques with high-risk characteristics is strongly associated with adverse cardiac events beyond the identification of coronary stenosis. Testing by coronary computed tomography angiography (CCTA) enables the identification of high-risk plaques (HRP). Referral for CCTA is presently based on pre-test probability estimates including clinical risk factors (CRFs); however, proteomics and/or genetic information could potentially improve patient selection for CCTA and, hence, identification of HRP.

Conditional deletion of in smooth muscle cells does not reduce early atherosclerosis in mice.

Background And Aims: C-C motif chemokine ligand 2 (CCL2) is a pro-inflammatory chemokine important for monocyte recruitment to the arterial wall and atherosclerotic plaques. Global knockout of reduces plaque formation and macrophage content in mice, but the importance of different plaque cell types in mediating this effect has not been resolved. Smooth muscle cells (SMCs) can adopt a potentially pro-inflammatory function with expression of CCL2.

Severe arterial injury heals with a complex clonal structure involving a large fraction of surviving smooth muscle cells.

Background And Aims: Smooth muscle cell (SMC) lineage cells in atherosclerosis and flow cessation-induced neointima are oligoclonal, being recruited from a tiny fraction of medial SMCs that modulate and proliferate. The present study aimed to investigate the clonal structure of SMC lineage cells healing more severe arterial injury.

Methods: Arterial injury (wire, stretch, and partial ligation) was inflicted on the right carotid artery in mice with homozygous, SMC-restricted, stochastically recombining reporter transgenes that produced mosaic expression of 10 distinguishable fluorescent phenotypes for clonal tracking.

Mechanisms of fibrous cap formation in atherosclerosis.

The fibrous cap is formed by smooth muscle cells that accumulate beneath the plaque endothelium. Cap rupture is the main cause of coronary thrombosis, leading to infarction and sudden cardiac death. Therefore, the qualities of the cap are primary determinants of the clinical outcome of coronary and carotid atherosclerosis.

Topography of immune cell infiltration in different stages of coronary atherosclerosis revealed by multiplex immunohistochemistry.

Background: Aim of this study was to investigate immune cells and subsets in different stages of human coronary artery disease with a novel multiplex immunohistochemistry (mIHC) technique.

Methods: Human left anterior descending coronary artery specimens were analyzed: eccentric intimal thickening (N = 11), pathological intimal thickening (N = 10), fibroatheroma (N = 9), and fibrous plaque (N = 9). Eccentric intimal thickening was considered normal, and pathological intimal thickening, fibroatheroma, and fibrous plaque were considered diseased coronary arteries.

Semaglutide treatment attenuates vessel remodelling in ApoE-/- mice following vascular injury and blood flow perturbation.

Background And Aims: Randomized clinical studies have shown a reduction in cardiovascular outcomes with glucagon-like peptide 1 receptor agonist (GLP-1RA) treatment with the hypothesized mechanisms being an underlying effect on atherosclerosis. Here, we aimed to assess the pharmacological effects of semaglutide in an atheroprone murine model that recapitulates central mechanisms related to vascular smooth muscle cell (VSMC) phenotypic switching and endothelial dysfunction known to operate within the atherosclerotic plaque.

Methods: In study A, we employed an electrical current to the carotid artery in ApoE-/- mice to induce severe VSMC injury and death, after which the arteries were allowed to heal for 4 weeks.

Low-Density Lipoprotein Cholesterol Is Predominantly Associated With Atherosclerotic Cardiovascular Disease Events in Patients With Evidence of Coronary Atherosclerosis: The Western Denmark Heart Registry.

Background: Low-density lipoprotein cholesterol (LDL-C) is an important causal risk factor for atherosclerotic cardiovascular disease (ASCVD). However, a sizable proportion of middle-aged individuals with elevated LDL-C level have not developed coronary atherosclerosis as assessed by coronary artery calcification (CAC). Whether presence of CAC modifies the association of LDL-C with ASCVD risk is unknown.

The Phenotypic Responses of Vascular Smooth Muscle Cells Exposed to Mechanical Cues.

During the development of atherosclerosis and other vascular diseases, vascular smooth muscle cells (SMCs) located in the intima and media of blood vessels shift from a contractile state towards other phenotypes that differ substantially from differentiated SMCs. In addition, these cells acquire new functions, such as the production of alternative extracellular matrix (ECM) proteins and signal molecules. A similar shift in cell phenotype is observed when SMCs are removed from their native environment and placed in a culture, presumably due to the absence of the physiological signals that maintain and regulate the SMC phenotype in the vasculature.

Histone deacetylase 9 promotes endothelial-mesenchymal transition and an unfavorable atherosclerotic plaque phenotype.

Endothelial-mesenchymal transition (EndMT) is associated with various cardiovascular diseases and in particular with atherosclerosis and plaque instability. However, the molecular pathways that govern EndMT are poorly defined. Specifically, the role of epigenetic factors and histone deacetylases (HDACs) in controlling EndMT and the atherosclerotic plaque phenotype remains unclear.

High-fructose feeding does not induce steatosis or non-alcoholic fatty liver disease in pigs.

Non-alcoholic fatty liver disease (NAFLD) is an increasingly prevalent condition that has been linked to high-fructose corn syrup consumption with induction of hepatic de novo lipogenesis (DNL) as the suggested central mechanism. Feeding diets very high in fructose (> 60%) rapidly induce several features of NAFLD in rodents, but similar diets have not yet been applied in larger animals, such as pigs. With the aim to develop a large animal NAFLD model, we analysed the effects of feeding a high-fructose (HF, 60% w/w) diet for four weeks to castrated male Danish Landrace-York-Duroc pigs.

Arterial Sca1 Vascular Stem Cells Generate De Novo Smooth Muscle for Artery Repair and Regeneration.

Rapid regeneration of smooth muscle after vascular injury is essential for maintaining arterial function. The existence and putative roles of resident vascular stem cells (VSCs) in artery repair are controversial, and vessel regeneration is thought to be mediated by proliferative expansion of pre-existing smooth muscle cells (SMCs). Here, we performed cell fate mapping and single-cell RNA sequencing to identify Sca1 VSCs in the adventitial layer of artery walls.

Vimentin deficiency in macrophages induces increased oxidative stress and vascular inflammation but attenuates atherosclerosis in mice.

The aim was to clarify the role of vimentin, an intermediate filament protein abundantly expressed in activated macrophages and foam cells, in macrophages during atherogenesis. Global gene expression, lipid uptake, ROS, and inflammation were analyzed in bone-marrow derived macrophages from vimentin-deficient (Vim) and wild-type (Vim) mice. Atherosclerosis was induced in Ldlr mice transplanted with Vim and Vim bone marrow, and in Vim and Vim mice injected with a PCSK9 gain-of-function virus.

Diet-Induced Abdominal Obesity, Metabolic Changes, and Atherosclerosis in Hypercholesterolemic Minipigs.

Background: Obesity and metabolic syndrome (MetS) are major risk factors for atherosclerotic diseases; however, a causal link remains elusive. Animal models resembling human MetS and its complications, while important, are scarce. We aimed at developing a porcine model of human MetS.

Diverse cellular architecture of atherosclerotic plaque derives from clonal expansion of a few medial SMCs.

Fibrous cap smooth muscle cells (SMCs) protect atherosclerotic lesions from rupturing and causing thrombosis, while other plaque SMCs may have detrimental roles in plaque development. To gain insight into recruitment of different plaque SMCs, we mapped their clonal architecture in aggregation chimeras of eGFP+Apoe-/- and Apoe-/- mouse embryos and in mice with a mosaic expression of fluorescent proteins in medial SMCs that were rendered atherosclerotic by PCSK9-induced hypercholesterolemia. Fibrous caps in aggregation chimeras were found constructed from large, endothelial-aligned layers of either eGFP+ or nonfluorescent SMCs, indicating substantial clonal expansion of a few cells.

Treatment with a human recombinant monoclonal IgG antibody against oxidized LDL in atherosclerosis-prone pigs reduces cathepsin S in coronary lesions.

Background: Immunization with oxidized LDL (oxLDL) reduces atherosclerosis in rodents. We tested the hypothesis that treatment with a human recombinant monoclonal antibody against oxLDL will reduce the burden or composition of atherosclerotic lesions in hypercholesterolemic minipigs.

Methods And Results: Thirty-eight hypercholesterolemic minipigs with defective LDL receptors were injected with an oxLDL antibody or placebo weekly for 12weeks.

Differences in Hypercholesterolemia and Atherogenesis Induced by Common Androgen Deprivation Therapies in Male Mice.

Background: Treatment of prostate cancer often involves androgen deprivation therapy (ADT) by gonadotropin-releasing hormone (GnRH) receptor agonists, GnRH receptor antagonists, or orchiectomy. ADT may increase the rate of cardiovascular disease events, but recent clinical studies suggested that not all means of ADT carry the same risk, raising the possibility of non-testosterone-mediated effects of different forms of ADT on atherosclerosis. Here we compared effects of ADT on atherosclerosis in intact and orchiectomized Apoe-deficient mice.

Myocardial and Peripheral Ischemia Causes an Increase in Circulating Pregnancy-Associated Plasma Protein-A in Non-atherosclerotic, Non-heparinized Pigs.

The usefulness of circulating pregnancy-associated plasma protein-A (PAPP-A) as a biomarker for acute coronary syndrome (ACS) is widely debated. We used the pig as a model to assess PAPP-A dynamics in the setting of myocardial ischemia. Induction of myocardial ischemia by ligation of the left anterior descending (LAD) coronary artery caused a systemic rise in PAPP-A.

Disturbed Laminar Blood Flow Vastly Augments Lipoprotein Retention in the Artery Wall: A Key Mechanism Distinguishing Susceptible From Resistant Sites.

Objective: Atherosclerosis develops initially at branch points and in areas of high vessel curvature. Moreover, experiments in hypercholesterolemic mice have shown that the introduction of disturbed flow in straight, atherosclerosis-resistant arterial segments turns them highly atherosclerosis susceptible. Several biomechanical mechanisms have been proposed, but none has been demonstrated.

Inducing Persistent Flow Disturbances Accelerates Atherogenesis and Promotes Thin Cap Fibroatheroma Development in D374Y-PCSK9 Hypercholesterolemic Minipigs.

Background: Although disturbed flow is thought to play a central role in the development of advanced coronary atherosclerotic plaques, no causal relationship has been established. We evaluated whether inducing disturbed flow would cause the development of advanced coronary plaques, including thin cap fibroatheroma.

Methods And Results: D374Y-PCSK9 hypercholesterolemic minipigs (n=5) were instrumented with an intracoronary shear-modifying stent (SMS).

Mechanisms of plaque formation and rupture.

Atherosclerosis causes clinical disease through luminal narrowing or by precipitating thrombi that obstruct blood flow to the heart (coronary heart disease), brain (ischemic stroke), or lower extremities (peripheral vascular disease). The most common of these manifestations is coronary heart disease, including stable angina pectoris and the acute coronary syndromes. Atherosclerosis is a lipoprotein-driven disease that leads to plaque formation at specific sites of the arterial tree through intimal inflammation, necrosis, fibrosis, and calcification.

Induction of atherosclerosis in mice and hamsters without germline genetic engineering.

Rationale: Atherosclerosis can be achieved in animals by germline genetic engineering, leading to hypercholesterolemia, but such models are constrained to few species and strains, and they are difficult to combine with other powerful techniques involving genetic manipulation or variation.

Objective: To develop a method for induction of atherosclerosis without germline genetic engineering.

Methods And Results: Recombinant adeno-associated viral vectors were engineered to encode gain-of-function proprotein convertase subtilisin/kexin type 9 mutants, and mice were given a single intravenous vector injection followed by high-fat diet feeding.