scholarly journals Identification of CD34+/PGDFRα+ Valve Interstitial Cells (VICs) in Human Aortic Valves: Association of Their Abundance, Morphology and Spatial Organization with Early Calcific Remodeling

2020 ◽  
Vol 21 (17) ◽  
pp. 6330
Author(s):  
Grzegorz J. Lis ◽  
Andrzej Dubrowski ◽  
Maciej Lis ◽  
Bernard Solewski ◽  
Karolina Witkowska ◽  
...  
Keyword(s):  
Heart Valves ◽  
Spatial Organization ◽  
Three Dimensional ◽  
Interstitial Cells ◽  
Dimensional Structure ◽  
Aortic Valves ◽  
Valve Interstitial Cells ◽  
Valve Tissue ◽  
Early Signs ◽  
Younger Age

Aortic valve interstitial cells (VICs) constitute a heterogeneous population involved in the maintenance of unique valvular architecture, ensuring proper hemodynamic function but also engaged in valve degeneration. Recently, cells similar to telocytes/interstitial Cajal-like cells described in various organs were found in heart valves. The aim of this study was to examine the density, distribution, and spatial organization of a VIC subset co-expressing CD34 and PDGFRα in normal aortic valves and to investigate if these cells are associated with the occurrence of early signs of valve calcific remodeling. We examined 28 human aortic valves obtained upon autopsy. General valve morphology and the early signs of degeneration were assessed histochemically. The studied VICs were identified by immunofluorescence (CD34, PDGFRα, vimentin), and their number in standardized parts and layers of the valves was evaluated. In order to show the complex three-dimensional structure of CD34+/PDGFRα+ VICs, whole-mount specimens were imaged by confocal microscopy, and subsequently rendered using the Imaris (Bitplane AG, Zürich, Switzerland) software. CD34+/PDGFRα+ VICs were found in all examined valves, showing significant differences in the number, distribution within valve tissue, spatial organization, and morphology (spherical/oval without projections; numerous short projections; long, branching, occasionally moniliform projections). Such a complex morphology was associated with the younger age of the subjects, and these VICs were more frequent in the spongiosa layer of the valve. Both the number and percentage of CD34+/PDGFRα+ VICs were inversely correlated with the age of the subjects. Valves with histochemical signs of early calcification contained a lower number of CD34+/PDGFRα+ cells. They were less numerous in proximal parts of the cusps, i.e., areas prone to calcification. The results suggest that normal aortic valves contain a subpopulation of CD34+/PDGFRα+ VICs, which might be involved in the maintenance of local microenvironment resisting to pathologic remodeling. Their reduced number in older age could limit the self-regenerative properties of the valve stroma.

scholarly journals Heme-Mediated Activation of the Nrf2/HO-1 Axis Attenuates Calcification of Valve Interstitial Cells

Biomedicines ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 427
Author(s):  
Enikő Balogh ◽  
Arpan Chowdhury ◽  
Haneen Ababneh ◽  
Dávid Máté Csiki ◽  
Andrea Tóth ◽  
...  
Keyword(s):  
Target Gene ◽  
Interstitial Cells ◽  
Protective Role ◽  
Heme Oxygenase 1 ◽  
Related Factor ◽  
Valvular Interstitial Cells ◽  
Aortic Valves ◽  
Antioxidant Genes ◽  
Valve Interstitial Cells ◽  
Nrf2 Target Gene

Calcific aortic valve stenosis (CAVS) is a heart disease characterized by the progressive fibro-calcific remodeling of the aortic valves, an actively regulated process with the involvement of the reactive oxygen species-mediated differentiation of valvular interstitial cells (VICs) into osteoblast-like cells. Nuclear factor erythroid 2-related factor 2 (Nrf2) regulates the expression of a variety of antioxidant genes, and plays a protective role in valve calcification. Heme oxygenase-1 (HO-1), an Nrf2-target gene, is upregulated in human calcified aortic valves. Therefore, we investigated the effect of Nrf2/HO-1 axis in VIC calcification. We induced osteogenic differentiation of human VICs with elevated phosphate and calcium-containing osteogenic medium (OM) in the presence of heme. Heme inhibited Ca deposition and OM-induced increase in alkaline phosphatase and osteocalcin (OCN) expression. Heme induced Nrf2 and HO-1 expression in VICs. Heme lost its anti-calcification potential when we blocked transcriptional activity Nrf2 or enzyme activity of HO-1. The heme catabolism products bilirubin, carbon monoxide, and iron, and also ferritin inhibited OM-induced Ca deposition and OCN expression in VICs. This study suggests that heme-mediated activation of the Nrf2/HO-1 pathway inhibits the calcification of VICs. The anti-calcification effect of heme is attributed to the end products of HO-1-catalyzed heme degradation and ferritin.

scholarly journals The role of CTCF in regulating nuclear organization

2008 ◽  
Vol 205 (4) ◽  
pp. 747-750 ◽  
Author(s):  
Adam Williams ◽  
Richard A. Flavell
Keyword(s):  
Long Range ◽  
Dna Sequences ◽  
Spatial Organization ◽  
Zinc Finger Protein ◽  
Nuclear Organization ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Binding Factor ◽  
Long Range Interactions ◽  
Regulatory Functions

The spatial organization of the genome is thought to play an important part in the coordination of gene regulation. New techniques have been used to identify specific long-range interactions between distal DNA sequences, revealing an ever-increasing complexity to nuclear organization. CCCTC-binding factor (CTCF) is a versatile zinc finger protein with diverse regulatory functions. New data now help define how CTCF mediates both long-range intrachromosomal and interchromosomal interactions, and highlight CTCF as an important factor in determining the three-dimensional structure of the genome.

scholarly journals Metformin alleviates the calcification of aortic valve interstitial cells through activating the PI3K/AKT pathway in an AMPK dependent way

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Qiao En ◽  
Huang Zeping ◽  
Wang Yuetang ◽  
Wang Xu ◽  
Wang Wei
Keyword(s):  
Aortic Valve ◽  
Signaling Pathways ◽  
Signaling Pathway ◽  
Interstitial Cells ◽  
Akt Signaling ◽  
Akt Signaling Pathway ◽  
Aortic Valves ◽  
Valve Interstitial Cells ◽  
Pathological Mechanism

Abstract Background Calcific aortic valve disease (CAVD) is the most prevalent valvular disease worldwide. However, no effective treatment could delay or prevent the progression of the disease due to the poor understanding of its pathological mechanism. Many studies showed that metformin exerted beneficial effects on multiple cardiovascular diseases by mediating multiple proteins such as AMPK, NF-κB, and AKT. This study aims to verify whether metformin can inhibit aortic calcification through the PI3K/AKT signaling pathway. Methods We first analyzed four microarray datasets to screen differentially expressed genes (DEGs) and signaling pathways related to CAVD. Then aortic valve samples were used to verify selected genes and pathways through immunohistochemistry (IHC) and western blot (WB) assays. Aortic valve interstitial cells (AVICs) were isolated from non-calcific aortic valves and then cultured with phosphate medium (PM) with or without metformin to verify whether metformin can inhibit the osteogenic differentiation and calcification of AVICs. Finally, we used inhibitors and siRNA targeting AMPK, NF-κB, and AKT to study the mechanism of metformin. Results We screened 227 DEGs; NF-κB and PI3K/AKT signaling pathways were implicated in the pathological mechanism of CAVD. IHC and WB experiments showed decreased AMPK and AKT and increased Bax in calcific aortic valves. PM treatment significantly reduced AMPK and PI3K/AKT signaling pathways, promoted Bax/Bcl2 ratio, and induced AVICs calcification. Metformin treatment ameliorated AVICs calcification and apoptosis by activating the PI3K/AKT signaling pathway. AMPK activation and NF-κB inhibition could inhibit AVICs calcification induced by PM treatment; however, AMPK and AKT inhibition reversed the protective effect of metformin. Conclusions This study, for the first time, demonstrates that metformin can inhibit AVICs in vitro calcification by activating the PI3K/AKT signaling pathway; this suggests that metformin may provide a potential target for the treatment of CAVD. And the PI3K/AKT signaling pathway emerges as an important regulatory axis in the pathological mechanism of CAVD.

Abstract 18216: Epigenetic Up-regulation of α-smooth Muscle Actin Expression and Cell Aggregation in Human Aortic Valve Interstitial Cells Promotes Calcific Nodule Formation

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Rui Song ◽  
David A. Fullerton ◽  
Lihua Ao ◽  
Kesen Zhao ◽  
Xianzhong Meng
Keyword(s):  
Smooth Muscle ◽  
Aortic Valve ◽  
Smooth Muscle Actin ◽  
Cell Aggregation ◽  
Interstitial Cells ◽  
Nodule Formation ◽  
Muscle Actin ◽  
Aortic Valves ◽  
Valve Interstitial Cells ◽  
Tgf Β1

Older people are at risk of calcific aortic valve disease. Aortic valve interstitial cells (AVICs) play an important role in nodular calcification in aortic valve leaflets. AVICs in human aortic valves consist of fibroblasts and myofibroblasts that express α-smooth muscle actin (α-SMA). We have observed that AVICs of diseased aortic valves have greater osteogenic activities. However, molecular mechanism underlying AVIC formation of calcification nodules is not well understood. We hypothesized that an epigenetic mechanism promotes AVIC calcification nodule formation through induction of α-SMA expression and cell aggregation. Methods and Results: MiRNA profiles in AVICs from normal and diseased human aortic valves were analyzed by miRNA array and real-time qPCR. Diseased AVICs displayed higher levels of miR-486. Immunoblotting and immunofluorescence staining revealed that diseased AVICs had higher levels of α-SMA and α-SMA fibers. Inhibition of miR-486 by lentiviral-delivered miR-486 antagomir in diseased AVICs suppressed α-SMA expression and cell aggregation, resulting in reduced calcification nodule formation. Conversely, lentiviral-delivered miR-486 mimic in normal AVICs induced α-SMA expression and cell aggregation, leading to exacerbated calcification nodule formation. Stimulation of normal AVICs with pro-osteogenic mediators TGF-β1 and BMP-2 up-regulated miR-486 levels. MiR-486 antagomir reduced α-SMA expression, cell aggregation and calcification nodule formation in cells exposed to TGF-β1 or BMP-2. Further, miR-486 mimic induced AKT phosphorylation. Inhibition of AKT decreased α-SMA expression and cell aggregation induced by miR-486 mimic in normal AVICs. Knockdown of α-SMA suppressed cell aggregation and calcification nodule formation. Conclusions: The pro-osteogenic phenotype of AVICs of diseased aortic valves is associated with up-regulated levels of miR-486 and α-SMA. MiR-486 modulates the AKT pathway to up-regulate α-SMA expression and cell aggregation that are required for calcification nodule formation. These novel findings indicate that miR-486 contributes to the mechanism underlying aortic valve calcification and appears to be a therapeutic target for suppression of valvular osteogenic activity.

Abstract 673: KLF10 is a Critical Mediator of Wnt Signaling in Aortic Valve Interstitial Cells

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Nalini M Rajamannan ◽  
Muzaffer Cicek ◽  
John Hawse ◽  
Thomas Spelsberg ◽  
Malayannan Subramaniam
Keyword(s):  
Wnt Signaling ◽  
Wnt Signaling Pathway ◽  
Fold Increase ◽  
Interstitial Cells ◽  
Aortic Valves ◽  
Valve Interstitial Cells ◽  
Over Expression ◽  
Differentiated Cells ◽  
Undifferentiated Cells

We have previously demonstrated that β-catenin plays important roles in valve calcification with a specific osteogenic phenotype defined by increased bone mineral content and overall valve thickening. Recent studies indicate that KLF10 may be involved in mediating the Wnt signaling pathway in bone, which is known to play critical roles in osteoblast differentiation and mineralization. Therefore, we sought to test the role of KLF10 in mediating Wnt signaling, as well as differentiation and mineralization, in valve interstitial cells (VICs) isolated from porcine valves. Exposure of VICs to differentiation media led to increased expression of Runx2, Sox9 and osteocalcin. Differentiated cells also stained positive with Von Kossa while undifferentiated cells stained negative confirming the induction of an osteogenic phenotype. As expected, over-expression of both Lef1 and β-catenin led to activation of the top-flash reporter when transfected into VICs. Interestingly, over-expression of KLF10 also significantly up-regulated the top-flash reporter alone and further enhanced the activity of both Lef1 and β-catenin when co-transfected. We further confirmed the role of TIEG in an atherosclerotic mouse model ApoE/LRP5 double KO and found a two-fold increase in KLF10, Lrp6, and Runx2 expression in the cholesterol treated aortic valves as compared to controls. These data suggested that KLF10, Lef1 and β-catenin interact with each other to form a transcriptionally active protein complex leading to enhanced Wnt signaling in VICs. This possibility was further confirmed by the observation that KLF10 and β-catenin co-localize with one another in the nucleus of VICs following stimulation with LiCl and/or TGF-β. Taken together, these data implicate an important role for KLF10 in mediating Wnt signaling and Lef1 transcriptional activity in VICs, and implicate a potential role for canonical Wnt signaling in the observed osteogenic bone phenotype of cardiac aortic valves.

scholarly journals A novel source of arterial valve cells linked to bicuspid aortic valve without raphe in mice

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Lorriane Eley ◽  
Ahlam MS Alqahtani ◽  
Donal MacGrogan ◽  
Rachel V Richardson ◽  
Lindsay Murphy ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Bicuspid Aortic Valve ◽  
Congenital Malformations ◽  
Heart Valves ◽  
Atrioventricular Valve ◽  
Aortic Valves ◽  
Mesenchymal Transition ◽  
Valve Interstitial Cells ◽  
Valve Formation ◽  
Dependent Mechanism

Abnormalities of the arterial valve leaflets, predominantly bicuspid aortic valve, are the commonest congenital malformations. Although many studies have investigated the development of the arterial valves, it has been assumed that, as with the atrioventricular valves, endocardial to mesenchymal transition (EndMT) is the predominant mechanism. We show that arterial is distinctly different from atrioventricular valve formation. Whilst the four septal valve leaflets are dominated by NCC and EndMT-derived cells, the intercalated leaflets differentiate directly from Tnnt2-Cre+/Isl1+ progenitors in the outflow wall, via a Notch-Jag dependent mechanism. Further, when this novel group of progenitors are disrupted, development of the intercalated leaflets is disrupted, resulting in leaflet dysplasia and bicuspid valves without raphe, most commonly affecting the aortic valve. This study thus overturns the dogma that heart valves are formed principally by EndMT, identifies a new source of valve interstitial cells, and provides a novel mechanism for causation of bicuspid aortic valves without raphe.

scholarly journals Decreased Glucagon-Like Peptide-1 Is Associated With Calcific Aortic Valve Disease: GLP-1 Suppresses the Calcification of Aortic Valve Interstitial Cells

2021 ◽  
Vol 8 ◽  
Author(s):  
Fan Xiao ◽  
Qing Zha ◽  
Qianru Zhang ◽  
Qihong Wu ◽  
Zhongli Chen ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Valve Disease ◽  
Interstitial Cells ◽  
Valve Disease ◽  
Dependent Manner ◽  
Calcific Aortic Valve Disease ◽  
Aortic Valves ◽  
Valve Interstitial Cells ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Objectives: This study explores the concentration and role of glucagon-like peptide-1 (GLP-1) in calcific aortic valve disease (CAVD).Background: Calcific aortic valve disease is a chronic disease presenting with aortic valve degeneration and mineralization. We hypothesized that the level of GLP-1 is associated with CAVD and that it participates in the calcification of aortic valve interstitial cells (AVICs).Methods: We compared the concentration of GLP-1 between 11 calcific and 12 normal aortic valve tissues by immunohistochemical (IHC) analysis. ELISA was used to measure GLP-1 in serum of the Control (n = 197) and CAVD groups (n = 200). The effect of GLP-1 on the calcification of AVICs and the regulation of calcific gene expression were also characterized.Results: The GLP-1 concentration in the calcific aortic valves was 39% less than that in the control non-calcified aortic valves. Its concentration in serum was 19.3% lower in CAVD patients. Multivariable regression analysis demonstrated that GLP-1 level was independently associated with CAVD risk. In vitro, GLP-1 antagonized AVIC calcification in a dose- and time-dependent manner and it down-regulated RUNX2, MSX2, BMP2, and BMP4 expression but up-regulated SOX9 expression.Conclusions: A reduction in GLP-1 was associated with CAVD, and GLP-1 participated in the mineralization of AVICs by regulating specific calcific genes. GLP-1 warrants consideration as a novel treatment target for CAVD.

Abstract 60: Shear Stress Maintains Endocardial Phenotype in Ipsc Derived Endocardial Cells

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Mark Vander Roest ◽  
Camryn Johnson ◽  
H. Scott Baldwin ◽  
W. David Merryman
Keyword(s):  
Shear Stress ◽  
Heart Valves ◽  
Interstitial Cells ◽  
Patient Specific ◽  
Cell Phenotype ◽  
Valve Interstitial Cells ◽  
Human Ipscs ◽  
Tissue Engineered Heart Valves ◽  
Mesenchymal Transformation ◽  
Emt Markers

Objectives: Specialized endocardial cells are responsible for the development of heart valves in utero . During a highly regulated morphogenetic process, these endocardial cells undergo endothelial-to-mesenchymal transformation (EMT) to become valve interstitial cells (VICs) and reorganize the extracellular matrix to form the structure of the valves. Potentially, induced pluripotent stem cells (iPSCs) may be coaxed into endocardial cells, then to VICs, to yield a suitable cell source for tissue engineered heart valves. Unfortunately, no method to generate iPSC derived endocardial cells exists. Current biochemical strategies utilize static culture, which does not represent the dynamic mechanical environment of the developing heart, which is known to affect differentiation and function of endocardial cells. Methods and Results: Human iPSCs were differentiated and purified to endothelial progenitors (CD34+), seeded onto collagen IV coated plates, and grown to confluency. Using a FlexCell system and a custom-built fluid shear device (A,B) , mechanical strain and shear stress were administered to the maturing cells independently, which were then assayed via qPCR for changes to endocardial and EMT markers. Bidirectional shear stress (C) was found to downregulate endothelial markers CD31, VE-cadherin and VEGFR2, as well as endocardial specific gene Nfatc1, yet increased expression of EMT markers BMP2 and Snai2. Conversely, unidirectional shear (D) increased Nfatc1 while causing lower expression of BMP2 and Snai2 than bidirectional shear. Cyclic strain decreased both endocardial and EMT markers (E) . Conclusions: These data suggest that unidirectional shear stress maintains an endocardial phenotype, while bidirectional shear stress induces EMT, promoting an interstitial cell phenotype. These stimuli may be utilized to maintain and expand patient-specific endocardial and valve interstitial cells for the creation of tissue engineered heart valves.

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