P479Extracellular S100A4 induces arterial smooth muscle cell activation in a RAGE-dependent manner

Background: It has been proposed that smooth muscle cells (SMCs) from the arterial wall are heterogeneous and that only a subset of medial SMCs are prone to accumulate into the intima leading to atheromatous plaque formation. We isolated 2 distinct SMC phenotypes from porcine coronary artery: spindle-shaped (S) and rhomboid (R). Biological features of R-SMCs (i.e. enhanced proliferative and migratory activities as well as poor level of differentiation) explain their capacity to accumulate into the intima. We identified S100A4 as being a marker of the R-SMCs in vitro and of intimal SMCs, both in pig and human. S100A4 is a Ca2+-binding protein that can also be secreted; it has extracellular functions probably via the receptor for advanced glycation end products (RAGE). Purpose: Explore the role of S100A4 in SMC phenotypic change, a phenomenon characteristic of atherosclerotic plaque formation. Methods and Results: Transfection of a human S100A4-containing plasmid in spindle-shaped (S) SMCs (devoid of S100A4) led to approximately 10% of S100A4-overexpressing SMCs, S100A4 release, and a transition towards a R-phenotype of the whole SMC population. Furthermore treatment of S-SMCs with S100A4-rich conditioned medium collected from S100A4-transfected S-SMCs induced a transition towards a phenotype typical of the R-SMCs, which was associated with decreased SMC differentiation markers, increased proliferation and migration, as well as induced proteolytic activity through activation of urokinase-type plasminogen activator (uPA), matrix metalloproteinases (MMP-1,-2, -3, and -9) and their inhibitors (TIMP-1). Furthermore, extracellular S100A4 yielded activation of NF-kB in a RAGE-dependent manner. Blockade of extracellular S100A4 in R-SMCs with S100A4 neutralizing antibody induced a transition from R- to S-phenotype, decreased proliferative activity and upregulation of SMC differentiation markers. In contrast, silencing of S100A4 mRNA in R-SMCs did not change the level of extracellular S100A4 nor SMC morphology in spite of decreased proliferative activity. Conclusions: Our results indicate that SMC phenotypic changes are essentially dependent on extracellular S100A4 activity. It could be a new target to prevent SMC accumulation during atherosclerosis and restenosi

Biological responses in stented arteries

Vascular walls change their dimension and mechanical properties in response to injury such as balloon angioplasty and endovascular stent implantation. Placement of bare metal stents induces neointimal proliferation/restenosis which progresses through different phases of repair with time involving a cascade of cellular reactions. These phases just like wound healing comprise distinct steps consisting of thrombosis, inflammation, proliferation, and migration followed by remodelling. It is noteworthy that animals show a rapid progression of healing after stent deployment compared with man. During stenting, endothelial cells are partially to completely destroyed or crushed along with medial wall injury and stretching promoting activation of platelets, and thrombus formation accompanied by inflammatory reaction. Macrophages and platelets play a central role through the release of cytokines and growth factors that induce vascular smooth muscle cell accumulation within the intima. Smooth muscle cells undergo complex phenotypic changes including migration and proliferation from the media towards the intima, and transition from a contractile to a synthetic phenotype; the molecular mechanisms responsible for this change are highlighted in this review. Since studies in animals and man show that smooth muscle cells play a dominant role in restenosis, drugs like rapamycin and paclitaxel have been coated on stent with polymers to allow local slow release of drugs, which have resulted in dramatic reduction of restenosis that was once the Achilles' heel of interventional cardiologist

Autologous transplantation of culture-born myofibroblasts into intact and injured rabbit ligaments

Purpose: The myofibroblast, a contractile fibroblastic cell expressing α-smooth muscle actin (α-SMA), has been reported to play a role in ligament healing. The aim of this study was to evaluate the feasibility of transplanting culture-derived myofibroblasts in injured rabbit medial collateral ligaments (MCL) and in intact anterior cruciate ligaments (ACL). Methods: Fibroblasts isolated from the iliotibial band were cultured in the presence of transforming growth factor beta-1 (TGF-β1) for fivedays and analysed for α-SMA expression. In a concentration of TGF-β1 ≥ 10ng/ml, the differentiation rate into myofibroblast was 90%. After labelling with PKH26, α-SMA -positive cells were transplanted in intact ACL and in injured MCL of ten rabbits. Results: Survival of PKH-26+ cells was seen in all intact and damaged ligaments one day after injection. The density of PKH-26+ cells had decreased at seven days postinjection in both ligaments. Double-positive PKH-26+/α-SMA+ cells were only observed in injured MCL at sevendays postinjection. Moreover, we found that genetically modified fibroblasts differentiate into myofibroblasts and can be transplanted into ligaments. Conclusions: Our data demonstrate that culture-born myofibroblasts survive and maintain α-SMA expression up to one week after transplantation. This study provides the first insight into the feasibility of transplanted mechanically active cells for ligament reconstructio

304Nuclear targeting apelin induces phenotypic transition of vascular smooth muscle cells

Background: Apelin, and its receptor APJ, are a peptidic system playing a crucial role in vascular diseases. However, the role of apelin in atherogenesis and smooth muscle cell (SMC) proliferation remains unclear. We isolated 2 distinct SMC phenotypes from porcine coronary artery: spindle-shaped (S) and rhomboid (R). Biological features of R-SMCs (i.e. enhanced proliferative and migratory activities as well as poor level of differentiation) explain their capacity to accumulate into the intima. S100A4 is a marker of R-SMCs in vitro and of intimal SMCs, both in pig and human. S100A4 is a Ca2+-binding protein that can also be secreted; it has extracellular functions probably via the receptor for advanced glycation end products (RAGE). Purpose: Investigate the effects of apelin on SMC phenotypic transition and S100A4 expression and release. Methods and Results: We observed that apelin was highly expressed in R-SMCs particularly in their nucleus. P-SORT software analysis of preproapelin sequence suggested that N-terminal truncated apelin may target the nucleus, and we confirmed this in SMCs by overexpression of mutated preproapelin-His-tag. Transfection of mutated preproapelin-His-tag encoding plasmid in differentiated S-SMCs induced a transition towards a R-phenotype associated with increased proliferative activity, downregulation of SMC differentiation markers (i.e. alpha-smooth muscle actin), and increased nuclear expression and release of S100A4. In contrast, transfection of S-SMCs with wild type preproapelin-His-tag encoding plasmid did not induce nuclear targeting of Apelin or S100A4, and did not change the S-phenotype. Stimulation of S-SMCs with PDGF-BB, known to induce a transition to the R-phenotype, yielded nuclear targeting of both apelin and S100A4. In vivo, Apelin was expressed in SMC nuclei of stent-induced intimal thickening while its expression in the media was mainly cytoplasmic. Conclusions: Our results suggest that nuclear targeting of apelin in SMCs acts on S100A4 expression and release, cell proliferation and differentiation. The pathophysiological consequences of this retargeting could be instrumental in the understanding of artherosclerosi

Corrigendum to "Cytostatic drugs differentially affect phenotypic features of porcine coronary artery smooth muscle cell populations" [FEBS Lett. 581 (2007) 5847–5851]

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Endothelial dysfunction in COVID-19: a position paper of the ESC Working Group for Atherosclerosis and Vascular Biology, and the ESC Council of Basic Cardiovascular Science

The COVID-19 pandemic is an unprecedented healthcare emergency causing mortality and illness across the world. Although primarily affecting the lungs, the SARS-CoV-2 virus also affects the cardiovascular system. In addition to cardiac effects, e.g. myocarditis, arrhythmias, and myocardial damage, the vasculature is affected in COVID-19, both directly by the SARS-CoV-2 virus, and indirectly as a result of a systemic inflammatory cytokine storm. This includes the role of the vascular endothelium in the recruitment of inflammatory leucocytes where they contribute to tissue damage and cytokine release, which are key drivers of acute respiratory distress syndrome (ARDS), in disseminated intravascular coagulation, and cardiovascular complications in COVID-19. There is also evidence linking endothelial cells (ECs) to SARS-CoV-2 infection including: (i) the expression and function of its receptor angiotensin-converting enzyme 2 (ACE2) in the vasculature; (ii) the prevalence of a Kawasaki disease-like syndrome (vasculitis) in COVID-19; and (iii) evidence of EC infection with SARS-CoV-2 in patients with fatal COVID-19. Here, the Working Group on Atherosclerosis and Vascular Biology together with the Council of Basic Cardiovascular Science of the European Society of Cardiology provide a Position Statement on the importance of the endothelium in the underlying pathophysiology behind the clinical presentation in COVID-19 and identify key questions for future research to address. We propose that endothelial biomarkers and tests of function (e.g. flow-mediated dilatation) should be evaluated for their usefulness in the risk stratification of COVID-19 patients. A better understanding of the effects of SARS-CoV-2 on endothelial biology in both the micro- and macrovasculature is required, and endothelial function testing should be considered in the follow-up of convalescent COVID-19 patients for early detection of long-term cardiovascular complications

Identifying the anti-inflammatory response to lipid lowering therapy: a position paper from the working group on atherosclerosis and vascular biology of the European Society of Cardiology

Dysregulated lipid metabolism induces an inflammatory and immune response leading to atherosclerosis. Conversely, inflammation may alter lipid metabolism. Recent treatment strategies in secondary prevention of atherosclerosis support beneficial effects of both anti-inflammatory and lipid-lowering therapies beyond current targets. There is a controversy about the possibility that anti-inflammatory effects of lipid-lowering therapy may be either independent or not of a decrease in low-density lipoprotein cholesterol. In this Position Paper, we critically interpret and integrate the results obtained in both experimental and clinical studies on anti-inflammatory actions of lipid-lowering therapy and the mechanisms involved. We highlight that: (i) besides decreasing cholesterol through different mechanisms, most lipid-lowering therapies share anti-inflammatory and immunomodulatory properties, and the anti-inflammatory response to lipid-lowering may be relevant to predict the effect of treatment, (ii) using surrogates for both lipid metabolism and inflammation as biomarkers or vascular inflammation imaging in future studies may contribute to a better understanding of the relative importance of different mechanisms of action, and (iii) comparative studies of further lipid lowering, anti-inflammation and a combination of both are crucial to identify effects that are specific or shared for each treatment strategy

Biomechanical factors in atherosclerosis: mechanisms and clinical implications†

Blood vessels are exposed to multiple mechanical forces that are exerted on the vessel wall (radial, circumferential and longitudinal forces) or on the endothelial surface (shear stress). The stresses and strains experienced by arteries influence the initiation of atherosclerotic lesions, which develop at regions of arteries that are exposed to complex blood flow. In addition, plaque progression and eventually plaque rupture is influenced by a complex interaction between biological and mechanical factors—mechanical forces regulate the cellular and molecular composition of plaques and, conversely, the composition of plaques determines their ability to withstand mechanical load. A deeper understanding of these interactions is essential for designing new therapeutic strategies to prevent lesion development and promote plaque stabilization. Moreover, integrating clinical imaging techniques with finite element modelling techniques allows for detailed examination of local morphological and biomechanical characteristics of atherosclerotic lesions that may be of help in prediction of future events. In this ESC Position Paper on biomechanical factors in atherosclerosis, we summarize the current ‘state of the art' on the interface between mechanical forces and atherosclerotic plaque biology and identify potential clinical applications and key questions for future researc

Translational opportunities of single-cell biology in atherosclerosis

The advent of single-cell biology opens a new chapter for understanding human biological processes and for diagnosing, monitoring, and treating disease. This revolution now reaches the field of cardiovascular disease (CVD). New technologies to interrogate CVD samples at single-cell resolution are allowing the identification of novel cell communities that are important in shaping disease development and direct towards new therapeutic strategies. These approaches have begun to revolutionize atherosclerosis pathology and redraw our understanding of disease development. This review discusses the state-of-the-art of single-cell analysis of atherosclerotic plaques, with a particular focus on human lesions, and presents the current resolution of cellular subpopulations and their heterogeneity and plasticity in relation to clinically relevant features. Opportunities and pitfalls of current technologies as well as the clinical impact of single-cell technologies in CVD patient care are highlighted, advocating for multidisciplinary and international collaborative efforts to join the cellular dots of CVD