Cardiac organoids reveal mechanisms of human cardiogenesis
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ABSTRACT: Self-organisation and coordinated morphogenesis of multiple cardiac lineages is essential for the development and function of the heart. However, the absence of a human in vitro model that mimics the basic lineage architecture of the heart hinders research into developmental mechanisms and congenital defects. Here, we describe the establishment of a reliable, lineage-controlled and high-throughput cardiac organoid platform. We show that cardiac mesoderm derived from human pluripotent stem cells robustly self-organises and differentiates into cardiomyocytes forming a cavity. Co-differentiation of cardiomyocytes and endothelial cells from cardiac mesoderm within these structures is required to form a separate endothelial layer. As in vivo, the epicardium engulfs these cardiac organoids, migrates into the cardiomyocyte layer and differentiates. Thus, the cardiac organoid platform represents a powerful resource for the quantitative and mechanistic analysis of early human cardiogenesis that is otherwise inaccessible.
Project description:Self-organisation and coordinated morphogenesis of multiple cardiac lineages is essential for the development and function of the heart1-3. However, the absence of a human in vitro model that mimics the basic lineage architecture of the heart hinders research into developmental mechanisms and congenital defects4. Here, we describe the establishment of a reliable, lineage-controlled and high-throughput cardiac organoid platform. We show that cardiac mesoderm derived from human pluripotent stem cells robustly self-organises and differentiates into cardiomyocytes forming a cavity. Co-differentiation of cardiomyocytes and endothelial cells from cardiac mesoderm within these structures is required to form a separate endothelial layer. As in vivo, the epicardium engulfs these cardiac organoids, migrates into the cardiomyocyte layer and differentiates. We use this model to demonstrate that cardiac cavity formation is controlled by a mesodermal WNT-BMP signalling axis. Disruption of one of the key BMP targets in cardiac mesoderm, the transcription factor HAND1, interferes with cavity formation, which is consistent with its role in early heart tube and left chamber development5. Thus, the cardiac organoid platform represents a powerful resource for the quantitative and mechanistic analysis of early human cardiogenesis and defects that are otherwise inaccessible. Beyond understanding congenital heart disease, cardiac organoids provide a foundation for future translational research into human cardiac disorders.
Project description:Human induced pluripotent stem cell (hiPSC)-derived cardiovascular cells are promising cell source for cell therapy to repair the heart. Cardiac microtissue consisted of cardiomyocytes and fibroblast cells exhibited much better physiological functions. How different cardiovascular cell types interact and evolve in 3D microenvironment is unknown. In this study, we performed single-cell transcriptome profiling of hiPSC-derived mini-cardiac organoid consisted of cardiomyocytes, endothelial cells and smooth muscle cells. Our analysis showed that cardiac fibroblasts emerged spontaneously in 3D microenvironment which in turn facilitated the maturation of cardiomyocytes. HiPSC-derived cardiomyocytes, endothelial cells and smooth muscle cells assembled into mini-cardiac organoid in collagen-matrigel after 2 weeks. Single-cell study uncovered significant cell fate shift and improvement in cardiomyocyte maturation status upon-multilineage co-culture. Ligand-receptor analysis identified DLK1-Notch signaling to be one of the most upregulated pathways in the fibroblast population. Modulate the activity of DLK1-Notch signaling affected the assembly of the mini-cardiac organoid and the expression of immune regulatory genes. Interestingly, transplantation of trilineage mini-cardiac organoid into a rat model of myocardial infarction leads to significant improvement of cardiac function. Collectively, our single-cell analysis of mini-cardiac organoid provided rich information about cell fate dynamics and multilineage cross-talks occurred in the 3D microenvironment, which bring new insight on the molecular mechanism that promotes cardiomyocyte maturation and heart repair.
Project description:During cardiac development, cells from the precardiac mesoderm fuse to form the primordial heart tube, which then grows by addition of further progenitors to the venous and arterial poles. In the zebrafish, wilms tumor 1 transcription factor a (wt1a) and b (wt1b) are expressed in the pericardial mesoderm at the venous pole of the forming heart tube. The pericardial mesoderm forms a single layered mesothelial sheet that contributes to further the growth of the myocardium, and forms the proepicardium. Proepicardial cells are subsequently transferred to the myocardial surface and give rise to the epicardium, the outer layer covering the myocardium in the adult heart. wt1a/b expression is downregulated during the transition from pericardium to myocardium, but remains high in proepicardial cells. Here we show that sustained wt1 expression impaired cardiomyocyte maturation including sarcomere assembly, ultimately affecting heart morphology and cardiac function. ATAC-seq data analysis of cardiomyocytes overexpressing wt1 revealed that chromatin regions associated with myocardial differentiation genes remain closed upon wt1b overexpression in cardiomyocytes, suggesting that wt1 represses a myocardial differentiation program. Indeed, a subset of wt1a/b-expressing cardiomyocytes changed their cell adhesion properties, delaminated from the myocardial epithelium, and upregulated the expression of epicardial genes, as confirmed by in vivo imaging. Thus, we conclude that wt1 acts as a break for cardiomyocyte differentiation by repressing chromatin opening at specific genomic loci and that sustained ectopic expression of wt1 in cardiomyocytes can lead to their transformation into epicardial cells.
Project description:During cardiac development, cells from the precardiac mesoderm fuse to form the primordial heart tube, which then grows by addition of further progenitors to the venous and arterial poles. In the zebrafish, wilms tumor 1 transcription factor a (wt1a) and b (wt1b) are expressed in the pericardial mesoderm at the venous pole of the forming heart tube. The pericardial mesoderm forms a single layered mesothelial sheet that contributes to further the growth of the myocardium, and forms the proepicardium. Proepicardial cells are subsequently transferred to the myocardial surface and give rise to the epicardium, the outer layer covering the myocardium in the adult heart. wt1a/b expression is downregulated during the transition from pericardium to myocardium, but remains high in proepicardial cells. Here we show that sustained wt1 expression impaired cardiomyocyte maturation including sarcomere assembly, ultimately affecting heart morphology and cardiac function. ATAC-seq data analysis of cardiomyocytes overexpressing wt1 revealed that chromatin regions associated with myocardial differentiation genes remain closed upon wt1b overexpression in cardiomyocytes, suggesting that wt1 represses a myocardial differentiation program. Indeed, a subset of wt1a/b-expressing cardiomyocytes changed their cell adhesion properties, delaminated from the myocardial epithelium, and upregulated the expression of epicardial genes, as confirmed by in vivo imaging. Thus, we conclude that wt1 acts as a break for cardiomyocyte differentiation by repressing chromatin opening at specific genomic loci and that sustained ectopic expression of wt1 in cardiomyocytes can lead to their transformation into epicardial cells.
Project description:KMT2D is required in the cardiac mesoderm, anterior heart field precursors and cardiomyocytes. Kmt2d deletion in cardiac mesoderm (Mesp1Cre) is embryonic lethal at E10.5 and mutants have hypoplastic hearts; Kmt2d deletion in anterior heart field precursors (Mef2cAHF::Cre) deletion is embryonic lethal at E13.5 and mutants have defects in septation of outflow tract and interventricular septum (IVS); Kmt2d deletion in cardiomyocytes (Tnnt2::Cre) deletion is embryonic lethal at E14.5 and mutants have defects in IVS septation and compact myocardium. The goal of this study is to compare changes in gene expression in these Kmt2d conditional deletion mutants and understand common or distinct pathways dysregulated in absence of KMT2D. Whole genome gene expression analysis was performed on RNA isolated from control and mutant embryonic hearts (or right ventricles and outflow tract for anterior heart field deletion samples). Libraries were prepared using Illumina TruSeq Paired-End Cluster Kit v3, and sequenced with the Illumina HiSeq 2500 system for pair-ended 100 base pairs (PE 100 bp).
Project description:Exosomes were isolated from differentiating stem cells at various stages such as pluripotency, mesoderm, cardiac mesoderm, and cardiomyocytes. Proteomics were done on isolated exosomes.
Project description:KMT2D is required in the cardiac mesoderm, anterior heart field precursors and cardiomyocytes. Kmt2d deletion in cardiac mesoderm (Mesp1Cre) is embryonic lethal at E10.5 and mutants have hypoplastic hearts; Kmt2d deletion in anterior heart field precursors (Mef2cAHF::Cre) deletion is embryonic lethal at E13.5 and mutants have defects in septation of outflow tract and interventricular septum (IVS); Kmt2d deletion in cardiomyocytes (Tnnt2::Cre) deletion is embryonic lethal at E14.5 and mutants have defects in IVS septation and compact myocardium. The goal of this study is to compare changes in gene expression in these Kmt2d conditional deletion mutants and understand common or distinct pathways dysregulated in absence of KMT2D.
Project description:Cardiopharyngeal mesoderm contributes to the formation of the heart and head muscles. However, the mechanisms governing cardiopharyngeal mesoderm specification remain unclear. Indeed, there is a lack of an in vitro model replicating the differentiation of both heart and head muscles to study these mechanisms. Such models are required to allow live-imaging and high throughput genetic and drug screening. Here, we show that the formation of self-organizing or pseudo-embryos from mouse embryonic stem cells (mESCs), also called gastruloids, reproduces cardiopharyngeal mesoderm specification towards cardiac and skeletal muscle lineages. By conducting a comprehensive temporal analysis of cardiopharyngeal mesoderm establishment and differentiation in gastruloids and comparing it to mouse embryos, we present the first evidence for skeletal myogenesis in gastruloids. By inferring lineage trajectories from the gastruloids single-cell transcriptomic data, we further suggest that heart and head muscles formed in gastruloids derive from cardiopharyngeal mesoderm progenitors. We identify different subpopulations of cardiomyocytes and skeletal muscles, which most likely correspond to different states of myogenesis with “head-like” and “trunk-like” skeletal myoblasts. These findings unveil the potential of mESC-derived gastruloids to undergo specification into both cardiac and skeletal muscle lineages, allowing the investigation of the mechanisms of cardiopharyngeal mesoderm differentiation in development and how this could be affected in congenital diseases.
Project description:Pathological cardiac hypertrophy is a leading cause of heart failure. The understanding of disease mechanisms is primarily based on experimental models, but knowledge of the full repertoire of cardiac cells and their gene expression profiles in the human heart is missing. Here, using large-scale single-nucleus transcriptomes, we highlight the transcriptional response of cardiomyocytes to pressure overload in humans with stenosis of the aortic valve and disclose major alterations in cellular cross-talk. Cardiomyocytes showed a reduction of incoming connections with endothelial cells and fibroblasts. Particularly Eph receptor tyrosine kinases, including the predominant EPHB1 gene, were significantly down-regulated in cardiomyocytes of the hypertrophied heart. We compared 5 AS patients to healthy patients from the human heart cell ATLAS (https://www.heartcellatlas.org). This repository contains the processed files from the single nuclei RNA-SEQ.
Project description:VEGF family members are important regulators of vascular functions. Promoting VEGFA signalling in aged mice has been shown to delay various aging phenotypes and extend the survival of aged mice. Although there is profound knowledge on functions of VEGFA, VEGFB has not been investigated in the context of cardiac aging. Our RNA data of aged mouse hearts revealed significant downregulation of Vegfb in the heart, specifically in endothelial cells and cardiomyocytes, while VEGFB expression was reduced in endothelial cells, fibroblasts and cardiomyocytes in aged human hearts. By contrast, VEGFB expression was exclusively reduced in cardiomyocytes of patients with cardiac hypertrophy. Hence, we investigated whether Vegfb gene therapy can revert age-dependent cardiac pathologies. We overexpressed Vegfb186, the soluble VEGFB isoform, via AAV9 vector transduction into 18-month-old C57Bl/6J male mice. AAV9-Vegfb treatment prevented progression age-related diastolic dysfunction and decreased cardiac fibrosis. We further found a rescue of aging-related left ventricular denervation in the hearts of AVV9-Vegfb treated old mice which was associated with an increase in heart rate variability. However, heart to body weight ratio and cardiomyocyte hypertrophy were increased in the AAV9-Vegfb treated mouse hearts, without alteration of cardiac systolic or diastolic function. Histological and transcriptomic analyses revealed that VEGFB186 induces compensatory cardiac hypertrophy which was accompanied by a rescued length-width-ratio, reduced fibrosis and the absence of cardiac inflammation. Cardiac single-nuclei RNA sequencing further suggested that AAV9-Vegfb treatment affects cardiac hypertrophy putatively via STAT3 which was validated in vitro. In conclusion, our data reveals that Vegfb overexpression partially reverses pathological alterations in the aging heart. Despite the overall improvement of the age-related cardiac phenotype, the AAV9-Vegfb-mediated induced cardiac hypertrophy which might reflect protective hypertrophy.