Endocardial/endothelial angiocrines regulate cardiomyocyte development and maturation and induce features of ventricular non-compaction
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ABSTRACT: Non-compaction cardiomyopathy is a devastating genetic disease caused by insufficient consolidation of ventricular wall muscle that can result in inadequate cardiac performance. Despite being the third most common cardiomyopathy, the mechanisms underlying the disease, including the cell types involved, are poorly understood. We have previously shown that endothelial cell-specific deletion of the chromatin remodeller gene Ino80 results in defective coronary vessel development that leads to ventricular non-compaction in embryonic mouse hearts. Here, we used single-cell RNA-sequencing to characterize endothelial and endocardial defects in Ino80-deficient hearts. We observed a pathological endocardial cell population in the non-compacted hearts and identified multiple dysregulated angiocrine factors that dramatically affected cardiomyocyte behaviour. We identified Col15A1 as a coronary vessel-secreted angiocrine factor, down-regulated by Ino80-deficiency, which functioned to promote cardiomyocyte proliferation. Furthermore, mutant endocardial and endothelial cells (ECs) AQ6 up-regulated expression of secreted factors, such as Tgfbi, Igfbp3, Isg15, and Adm, which decreased cardiomyocyte proliferation and increased maturation. These findings support a model where coronary ECs normally promote myocardial compaction through secreted factors, but that endocardial and ECs can secrete factors that contribute to non-compaction under pathological conditions.
Project description:Non-compaction cardiomyopathy is a devastating genetic disease caused by insufficient consolidation of ventricular wall muscle that can result in inadequate cardiac performance. Despite being the third most common cardiomyopathy, the mechanisms underlying the disease, including the cell types involved, are poorly understood. We explore the endothelial cell-specific deletion of the chromatin remodeler gene Ino80, which results in defective coronary vessel development that leads to ventricular non-compaction in embryonic mouse hearts. We observed a pathological endocardial cell population in the non-compacted hearts, and identified multiple dysregulated angiocrine factors that dramatically affected cardiomyocyte behavior.
Project description:To understand how Wnt/β-catenin signaling-activated cardiomyocytes (β-cat ON CMs) promote coronary vessel development, we performed single-cell RNA sequencing of endothelial cells (ECs) sorted from the hearts ablated β-cat ON CMs and those from control hearts, respectively. Our analyses indicated that β-cat ON CMs regulates coronary vessel development by promoting arterialization, a step in the transition of endocardial ECs to coronary ECs.
Project description:Purpose: Endothelial cell-specific knockout of the INO80 chromatin-remodeling complex in developing mouse embryos results in defective coronary angiogenesis. Transcriptome analysis on whole hearts was performed to understand how Ino80 regulates the genome to influence angiogenesis. Methods: mRNA was extracted from whole hearts after surgical removal from embryonic day 13.5 mice, either WT or Tie2-Ino80 KO, and prepped for Illumina sequencing using the NEBNext Ultra RNA Library Prep kit. Results: Deletion of Ino80 in the two major coronary progenetiors results in intermediate non-compaction phenotypes and an increase in E2F-mediated gene expression and cellular proliferation. Conclusions: Ino80 normally functions to suppress E2F-mediated proliferation in cardiac endothelial cells in order to promote productive angiogenesis and prevent underdevelopment of the myocardium heart muscle. Loss of this critical chromatin-remodeling function results in human disease phenotypes.
Project description:Given that the Nes-gfp allele specifically labels coronary ECs, endogenous GFP and the endomucin marker (which was highly expressed in endocardial cells) were used together to separate endocardial and coronary vascular endothelial cell subpopulations in different developmental stages
Project description:Endocardial cells lining the heart lumen are coronary vessel progenitors during embryogenesis. Re-igniting this developmental process in adults could regenerate blood vessels lost during cardiac injury, but this requires additional knowledge on molecular regulators. Here, we use mouse genetics and scRNAseq to identify novel regulators of endocardial angiogenesis and precisely assess the role of CXCL12/CXCR4 signaling. Time-specific lineage tracing demonstrated that endocardial cells differentiated in coronary endothelial cells primarily at mid-gestation. A new mouse line reporting CXCR4 activity—along with cell-specific gene deletions—revealed it was specifically required for artery morphogenesis rather than angiogenesis. Integrating scRNAseq data of endocardial-derived coronary vessels from mid- and late-gestation identified a Bmp2-expressing transitioning population specific to mid-gestation. Bmp2 stimulated endocardial angiogenesis in vitro and in injured neonatal mouse hearts. Our data shed light on how understanding the molecular mechanisms underlying endocardial angiogenesis can identify new potential therapeutic targets promoting revascularization of the injured heart.
Project description:Aims: To gain insight into heterogeneity of pacemaker and conduction cells within the sinoatrial node (SAN) and characterize the transcriptome of cardiac endothelial cells (ECs) at single-cell resolution. Methods and results: Single-cell transcriptome analysis of fluorescence activated cell sorting (FACS)-purified SAN cells and surrounding atrial cells from HCN4-GFP knockin mice at postnatal day 2 were performed. Subcluster analysis of SAN cardiomyocyte cluster identified three HCN4+ cell subtypes, including pacemaker cells (PCs), recently identified transitional cells (TCs), and a novel population of His-like conduction cells marked by His-bundle specific marker genes. We additionally refined the molecular signatures of PCs and TCs, and identified Vsnl1, Myl2 and Kcne1 as biomarkers of PCs, TCs and His-like respectively that persistently expressed in the SAN from E15.5 to adult. Furthermore, we observed three endothelial progenitor subtypes (endocardial progenitors, coronary vascular endothelial progenitors, and transitional endothelium migrated from endocardium to coronary vessels) in mouse heart and human fetal heart. These endothelial progenitor subtypes were further identified by mouse lineage tracing analysis. Conclusion: Our study provides a more comprehensive understanding of molecular and cellular signatures underlying pacemaking and conduction of the SAN, and offers new insight into lineage differentiation and diversification of cardiac ECs.
Project description:VEGFA administration has been explored as a pro-angiogenic therapy for cardiovascular diseases including heart failure for several years; however, many challenges remain. Here we investigate a different approach to augmenting VEGFA bioavailability, one that achieves more physiological VEGFA concentrations by deleting VEGFR1/FLT1, a VEGFA decoy receptor. We find that, following cryoinjury, zebrafish flt1 mutant hearts display enhanced coronary revascularization and endocardial expansion, increased cardiomyocyte dedifferentiation and proliferation, and decreased scarring. Suppressing Vegfa signaling in flt1 mutants abrogates the beneficial effects of flt1 deletion. Transcriptomic analyses of cryoinjured flt1 mutant hearts revealed enhanced endothelial MAPK/ERK signaling and downregulation of the transcription factor gene egr3. Using genetic tools, we observe egr3 upregulation in the regenerating endocardium and find that Egr3 promotes myofibroblast differentiation. These data suggest that with enhanced VEGFA bioavailability, the cardiac endothelium limits myofibroblast differentiation via egr3 downregulation, thereby providing a more permissive microenvironment for cardiomyocyte replenishment after injury.
Project description:Vascularization and efficient perfusion are long-standing challenges in cardiac tissue engineering. Here, we engineer perfusable microvascular constructs, wherein human embryonic stem cell-derived endothelial cells (hESC-ECs) are seeded both into patterned microchannels and the surrounding collagen matrix. In vitro, the hESC-ECs lining the luminal walls readily sprout and anastomose with de novo-formed endothelial tubes in the matrix under flow. When implanted on infarcted rat hearts, the perfusable microvessel grafts integrate with coronary vasculature to a greater degree than non-perfusable self-assembled constructs at 5 days post-implantation. Optical microangiography imaging reveal that perfusable grafts have 6-fold greater vascular density, 2.5-fold higher vascular velocities and >20-fold higher volumetric perfusion rates. Implantation of perfusable grafts containing additional hESC-derived cardiomyocytes show higher cardiomyocyte and vascular density. Thus, pre-patterned vascular networks enhance vascular remodeling and accelerate coronary perfusion, potentially supporting cardiac tissues after implantation. These findings should facilitate the next generation of cardiac tissue engineering design.
Project description:The role of shear stress, the frictional force of blood flow, on the endothelium has been well documented. Differences in shear stress can have profound effects on endothelial and blood vessel biology. Endothelial cells (ECs), termed endocardial ECs, line the heart chambers and are exposed to complex shear stress patterns. While it has been demonstrated that shear stress is important for heart development, little has been shown on the role of shear stress on adult ECs. 4D-MRI studies demonstrate regional differences in blood residence time. We sought to determine the effect of regional differences in endocardial shear stress on the endocardial transcriptome using RNA sequencing (RNA-seq) on 3 different regions (apex, mid-ventricle, outflow tract) from 8 adult pigs, for a total of 24 RNA-seq assays.
Project description:A better understanding of the pathways that regulate regeneration of the coronary vasculature is of fundamental importance for the advancement of strategies to treat patients with heart disease. By analyzing single cell transcriptome of resident cardiac endothelial cells (ECs) in adult mouse hearts under both healthy and myocardial infarction (MI) settings, we provide molecular definitions of murine cardiac endothelial heterogeneity and characterizations of pro-angiogenic resident ECs.