The coronavirus disease 2019 caused by SARS-CoV-2 infections imposes a major threat for the world's healthcare systems and is leading to thousands of deaths. Angiotensin-converting enzyme 2 (ACE2) has been identified as a potential receptor for SARS coronavirus 1 and is also considered the main receptor for SARS-CoV-2. 2 SARS-CoV-2 binds to ACE2 via its glycosylated outer membrane spike proteins. ACE2 is highly expressed in the lung and heart, and is known for its vital role in the cardiovascular system. 3-5 Although SARS-CoV-2 mainly invades alveolar epithelial cells, it can also cause myocardial injury, as assessed by increased troponin T and NT-proBNP levels accompanying increased cardiovascular symptoms in COVID-19-infected patients. 6,7 It is unclear whether elevated biomarkers of cardiac injury (or long-term effects on the cardiovascular system) are directly caused by viral infection of cardiac tissue or are secondary to hypoxia and systemic inflammation. However, patients with underlying cardiovascular disease represent a significant proportion of the patients who may suffer from a severe course after COVID-19 infection. 8 This situation may be aggravated by findings showing that ACE inhibitors, which are often used to treat cardiovascular diseases, augment the expression of the SARS-CoV-2 receptor ACE2 in lung cells. 9 This is probably mediated by an effect on angiotensin II, which is known to reduce ACE2 expression. 9 Thus, ACE inhibition decreases angiotensin II, leading to an indirect up-regulation of ACE2. 9 The effect of angiotensin II receptor blockers (ARBs), which primarily target the angiotensin receptor 1, is unclear. One may speculate that ARBs indirectly reduce ACE2 levels by augmenting free angiotensin II levels, which in turn is expected to downregulate ACE2 via activating the angiotensin receptor 2. However, the effect of the two different treatments on the expression of ACE2 in the heart requires further investigation.Therefore, we used single nuclei RNA sequencing to determine the expression of ACE and ACE2 in the different cell types of the human heart. Gene expression signatures were detected in cardiac tissues of five patients with aortic stenosis (AS) and two patients with heart failure with reduced ejection fraction (HFrEF) ( Figure 1A) and compared with with samples of one healthy donor heart (age: 63 years, male) that was not used for transplantation. After single nuclei RNA sequencing, data were pooled, and unsupervised clustering was performed with a total of 57 601 nuclei. We found 18 distinct clusters. Using cell type-specific gene markers, major cell types were annotated, including cardiomyocytes (six clusters), fibroblasts (one cluster), endothelial cells (three clusters), leucocytes (two clusters), pericytes (one cluster), and smooth muscle cells (one cluster) ( Figure 1B-D). ACE2 was expressed in cardiomyocytes (Cluster 0 and 1) and mural cells, particularly pericytes (Cluster 4), and was detected at a lower expression level in fibroblasts, endothelial cell, and leucocytes...

Background Stiffening of the aortic wall is a phenomenon consistently observed in age and in abdominal aortic aneurysm (AAA). However, its role in AAA pathophysiology is largely undefined. Methods and Results Using an established murine elastase-induced AAA model, we demonstrate that segmental aortic stiffening (SAS) precedes aneurysm growth. Finite element analysis (FEA) reveals that early stiffening of the aneurysm-prone aortic segment leads to axial (longitudinal) wall stress generated by cyclic (systolic) tethering of adjacent, more compliant wall segments. Interventional stiffening of AAA-adjacent aortic segments (via external application of surgical adhesive) significantly reduces aneurysm growth. These changes correlate with reduced segmental stiffness of the AAA-prone aorta (due to equalized stiffness in adjacent segments), reduced axial wall stress, decreased production of reactive oxygen species (ROS), attenuated elastin breakdown, and decreased expression of inflammatory cytokines and macrophage infiltration, as well as attenuated apoptosis within the aortic wall. Cyclic pressurization of segmentally stiffened aortic segments ex vivo increases the expression of genes related to inflammation and extracellular matrix (ECM) remodeling. Finally, human ultrasound studies reveal that aging, a significant AAA risk factor, is accompanied by segmental infrarenal aortic stiffening. Conclusions The present study introduces the novel concept of segmental aortic stiffening (SAS) as an early pathomechanism generating aortic wall stress and triggering aneurysmal growth, thereby delineating potential underlying molecular mechanisms and therapeutic targets. In addition, monitoring SAS may aid the identification of patients at risk for AAA.

The VinV concept is promising for minimally invasive beating heart repeat aortic or mitral valve replacement, using a stent-fixed sutureless prosthesis.

Rationale Accelerated arterial stiffening is a major complication of diabetes with no specific therapy available up to date. Objective The present study investigates the role of the osteogenic transcription factor Runx2 as a potential mediator and therapeutic target of aortic fibrosis and aortic stiffening in diabetes. Methods and Results Using a murine model of type 2 diabetes (db/db mice) we identify progressive structural aortic stiffening that precedes the onset of arterial hypertension. At the same time, Runx2 is aberrantly upregulated in the medial layer of db/db aortae as well as in thoracic aortic samples from type 2 diabetic patients. Vascular smooth muscle-specific overexpression of Runx2 in transgenic mice increases expression of its target genes, Col1a1 and Col1a2, leading to medial fibrosis and aortic stiffening. Interestingly, increased Runx2 expression per se is not sufficient to induce aortic calcification. Using in vivo and in vitro approaches, we further demonstrate that Runx2 expression in diabetes is regulated via a redox-sensitive pathway that involves a direct interaction of NF-κB with the Runx2 promoter. Conclusion In conclusion this study highlights Runx2 as a previously unrecognized inducer of vascular fibrosis in the setting of diabetes, promoting arterial stiffness irrespective of calcification.

Significance: Arterial blood vessels functionally and structurally adapt to altering hemodynamic forces in order to accommodate changing needs and to provide stress homeostasis. This ability is achieved at the cellular level by converting mechanical stimulation into biochemical signals (i.e., mechanotransduction). Physiological mechanical stress helps maintain vascular structure and function, whereas pathologic or aberrant stress may impair cellular mechano-signaling, and initiate or augment cellular processes that drive disease. Recent Advances: Reactive oxygen species (ROS) may represent an intriguing class of mechanically regulated second messengers. Chronically enhanced ROS generation may be induced by adverse mechanical stresses, and is associated with a multitude of vascular diseases. Although a causal relationship has clearly been demonstrated in large numbers of animal studies, an effective ROS-modulating therapy still remains to be established by clinical studies. Critical Issues and Future Directions: This review article focuses on the role of various mechanical forces (in the form of laminar shear stress, oscillatory shear stress, or cyclic stretch) as modulators of ROS-driven signaling, and their subsequent effects on vascular biology and homeostasis, as well as on specific diseases such as arteriosclerosis, hypertension, and abdominal aortic aneurysms. Specifically, it highlights the significance of the various NADPH oxidase (NOX) isoforms as critical ROS generators in the vasculature. Directed targeting of defined components in the complex network of ROS (mechano-)signaling may represent a key for successful translation of experimental findings into clinical practice. Antioxid. Redox Signal. 20,[914][915][916][917][918][919][920][921][922][923][924][925][926][927][928]

Results of our novel approach, integrating in vitro assessment into gene expression profiling, implicated chronic inflammation characterized by MMP-TIMP dysregulation, increased VEGFA expression, and TGF-β signalling in the development of dissection. Further investigation may reveal novel diagnostic biomarkers and uncover the mechanism(s) underlying ATAAD.

Pathological cardiac hypertrophy is a leading cause of heart failure, but knowledge of the full repertoire of cardiac cells and their gene expression profiles in the human hypertrophic heart is missing. Here, by using large-scale single-nucleus transcriptomics, we present the transcriptional response of human cardiomyocytes to pressure overload caused by aortic valve stenosis and describe major alterations in cardiac cellular crosstalk. Hypertrophied cardiomyocytes had reduced input from endothelial cells and fibroblasts. Genes encoding Eph receptor tyrosine kinases, particularly EPHB1, were significantly downregulated in cardiomyocytes of the hypertrophied heart. Consequently, EPHB1 activation by its ligand ephrin (EFN)B2, which is mainly expressed by endothelial cells, was reduced. EFNB2 inhibited cardiomyocyte hypertrophy in vitro, while silencing its expression in endothelial cells induced hypertrophy in co-cultured cardiomyocytes. Our human cell atlas of the hypertrophied heart highlights the importance of intercellular crosstalk in disease pathogenesis and provides a valuable resource.

C1039G/+ascending SMCs showed that apoptotic SMCs have increased elastolytic potential compared with viable cells, mostly because of caspase activity. Moreover, in vitro (1) cell membrane isolation, (2) immunofluorescence staining, and (3) scanning electron microscopy studies illustrate that caspases are expressed on the exterior cell surface of apoptotic SMCs. Conclusions-Caspase inhibition attenuates aneurysm development in an