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Miyazaki S, Aoyama D, Mukai M, Tada H. Epicardial scar dechanneling of the area adjacent to the left phrenic nerve in a patient with ventricular tachycardia. J Cardiovasc Electrophysiol 2019; 30:971-972. [PMID: 30883983 DOI: 10.1111/jce.13916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 03/04/2019] [Accepted: 03/06/2019] [Indexed: 11/29/2022]
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Perdios C, Parnall M, Pang KL, Loughna S. Altered haemodynamics causes aberrations in the epicardium. J Anat 2019; 234:800-814. [PMID: 30882904 PMCID: PMC6539700 DOI: 10.1111/joa.12977] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2019] [Indexed: 02/04/2023] Open
Abstract
During embryo development, the heart is the first functioning organ. Although quiescent in the adult, the epicardium is essential during development to form a normal four‐chambered heart. Epicardial‐derived cells contribute to the heart as it develops with fibroblasts and vascular smooth muscle cells. Previous studies have shown that a heartbeat is required for epicardium formation, but no study to our knowledge has shown the effects of haemodynamic changes on the epicardium. Since the aetiologies of many congenital heart defects are unknown, we suggest that an alteration in the heart's haemodynamics might provide an explanatory basis for some of them. To change the heart's haemodynamics, outflow tract (OFT) banding using a double overhang knot was performed on HH21 chick embryos, with harvesting at different developmental stages. The epicardium of the heart was phenotypically and functionally characterised using a range of techniques. Upon alteration of haemodynamics, the epicardium exhibited abnormal morphology at HH29, even though migration of epicardial cells along the surface of the heart was found to be normal between HH24 and HH28. The abnormal epicardial phenotype was exacerbated at HH35 with severe changes in the structure of the extracellular matrix (ECM). A number of genes tied to ECM production were also differentially expressed in HH29 OFT‐banded hearts, including DDR2 and collagen XII. At HH35, the differential expression of these genes was even greater with additional downregulation of collagen I and TCF21. In this study, the epicardium was found to be severely impacted by altered haemodynamics upon OFT banding. The increased volume of the epicardium at HH29, upon OFT‐banding, and the expression changes of ECM markers were the first indicative signs of aberrations in epicardial architecture; by HH35, the phenotype had progressed. The decrease in epicardial thickness at HH35 suggests an increase in tension, with a force acting perpendicular to the surface of the epicardium. Although the developing epicardium and the blood flowing through the heart are separated by the endocardium and myocardium, the data presented here demonstrate that altering the blood flow affects the structure and molecular expression of the epicardial layer. Due to the intrinsic role the epicardium in cardiogenesis, defects in epicardial formation could have a role in the formation of a wide range of congenital heart defects.
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Cao Y, Cao J. Covering and Re-Covering the Heart: Development and Regeneration of the Epicardium. J Cardiovasc Dev Dis 2018; 6:jcdd6010003. [PMID: 30586891 PMCID: PMC6463056 DOI: 10.3390/jcdd6010003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 12/13/2018] [Accepted: 12/19/2018] [Indexed: 12/23/2022] Open
Abstract
The epicardium, a mesothelial layer that envelops vertebrate hearts, has become a therapeutic target in cardiac repair strategies because of its vital role in heart development and cardiac injury response. Epicardial cells serve as a progenitor cell source and signaling center during both heart development and regeneration. The importance of the epicardium in cardiac repair strategies has been reemphasized by recent progress regarding its requirement for heart regeneration in zebrafish, and by the ability of patches with epicardial factors to restore cardiac function following myocardial infarction in mammals. The live surveillance of epicardial development and regeneration using zebrafish has provided new insights into this topic. In this review, we provide updated knowledge about epicardial development and regeneration.
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Bonet F, Pereira PNG, Bover O, Marques S, Inácio JM, Belo JA. CCBE1 is required for coronary vessel development and proper coronary artery stem formation in the mouse heart. Dev Dyn 2018; 247:1135-1145. [PMID: 30204931 DOI: 10.1002/dvdy.24670] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 09/04/2018] [Accepted: 09/04/2018] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Proper coronary vasculature development is essential for late-embryonic and adult heart function. The developmental regulation of coronary embryogenesis is complex and includes the coordinated activity of multiple signaling pathways. CCBE1 plays an important role during lymphangiogenesis, enhancing VEGF-C signaling, which is also required for coronary vasculature formation. However, whether CCBE1 plays a similar role during coronary vasculature development is still unknown. Here, we investigate the coronary vasculature development in Ccbe1 mutant embryos. RESULTS We show that Ccbe1 is expressed in the epicardium, like Vegf-c, and also in the sinus venosus (SV) at the stages of its contribution to coronary vasculature formation. We also report that absence of CCBE1 in cardiac tissue inhibited coronary growth that sprouts from the SV endocardium at the dorsal cardiac wall. This disruption of coronary formation correlates with abnormal processing of VEGF-C propeptides, suggesting VEGF-C-dependent signaling alteration. Moreover, Ccbe1 loss-of-function leads to the development of defective dorsal and ventral intramyocardial vessels. We also demonstrate that Ccbe1 mutants display delayed and mispatterned coronary artery (CA) stem formation. CONCLUSIONS CCBE1 is essential for coronary vessel formation, independent of their embryonic origin, and is also necessary for peritruncal vessel growth and proper CA stem patterning. Developmental Dynamics 247:1135-1145, 2018. © 2018 Wiley Periodicals, Inc.
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Niderla-BieliŃska J, Jankowska-Steifer E, Flaht-Zabost A, Gula G, Czarnowska E, Ratajska A. Pro epicardium: Current Understanding of its Structure, Induction, and Fate. Anat Rec (Hoboken) 2018; 302:893-903. [PMID: 30421563 DOI: 10.1002/ar.24028] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 08/20/2018] [Accepted: 08/30/2018] [Indexed: 12/24/2022]
Abstract
The proepicardium (PE) is a transitory extracardiac embryonic structure which plays a crucial role in cardiac morphogenesis and delivers various cell lineages to the developing heart. The PE arises from the lateral plate mesoderm (LPM) and is present in all vertebrate species. During development, mesothelial cells of the PE reach the naked myocardium either as free-floating aggregates in the form of vesicles or via a tissue bridge; subsequently, they attach to the myocardium and, finally, form the third layer of a mature heart-the epicardium. After undergoing epithelial-to-mesenchymal transition (EMT) some of the epicardial cells migrate into the myocardial wall and differentiate into fibroblasts, smooth muscle cells, and possibly other cell types. Despite many recent findings, the molecular pathways that control not only proepicardial induction and differentiation but also epicardial formation and epicardial cell fate are poorly understood. Knowledge about these events is essential because molecular mechanisms that occur during embryonic development have been shown to be reactivated in pathological conditions, for example, after myocardial infarction, during hypertensive heart disease or other cardiovascular diseases. Therefore, in this review we intended to summarize the current knowledge about PE formation and structure, as well as proepicardial cell fate in animals commonly used as models for studies on heart development. Anat Rec, 302:893-903, 2019. © 2018 Wiley Periodicals, Inc.
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Wang S, Huang W, Castillo HA, Kane MA, Xavier-Neto J, Trainor PA, Moise AR. Alterations in retinoic acid signaling affect the development of the mouse coronary vasculature. Dev Dyn 2018; 247:976-991. [PMID: 29806219 DOI: 10.1002/dvdy.24639] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Revised: 05/08/2018] [Accepted: 05/08/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND During the final stages of heart development the myocardium grows and becomes vascularized by means of paracrine factors and cell progenitors derived from the epicardium. There is evidence to suggest that retinoic acid (RA), a metabolite of vitamin A, plays an important role in epicardial-based developmental programming. However, the consequences of altered RA-signaling in coronary development have not been systematically investigated. RESULTS We explored the developmental consequences of altered RA-signaling in late cardiogenic events that involve the epicardium. For this, we used a model of embryonic RA excess based on mouse embryos deficient in the retinaldehyde reductase DHRS3, and a complementary model of embryonic RA deficiency based on pharmacological inhibition of RA synthesis. We found that alterations in embryonic RA signaling led to a thin myocardium and aberrant coronary vessel formation and remodeling. Both excess, and deficient RA-signaling are associated with reductions in ventricular coverage and density of coronary vessels, altered vessel morphology, and impaired recruitment of epicardial-derived mural cells. Using a combined transcriptome and proteome profiling approach, we found that RA treatment of epicardial cells influenced key signaling pathways relevant for cardiac development. CONCLUSIONS Epicardial RA-signaling plays critical roles in the development of the coronary vasculature needed to support myocardial growth. Developmental Dynamics 247:976-991, 2018. © 2018 Wiley Periodicals, Inc.
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Sayed A, Valente M, Sassoon D. Does cardiac development provide heart research with novel therapeutic approaches? F1000Res 2018; 7. [PMID: 30450195 PMCID: PMC6221076 DOI: 10.12688/f1000research.15609.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/24/2018] [Indexed: 01/04/2023] Open
Abstract
Embryonic heart progenitors arise at specific spatiotemporal periods that contribute to the formation of distinct cardiac structures. In mammals, the embryonic and fetal heart is hypoxic by comparison to the adult heart. In parallel, the cellular metabolism of the cardiac tissue, including progenitors, undergoes a glycolytic to oxidative switch that contributes to cardiac maturation. While oxidative metabolism is energy efficient, the glycolytic-hypoxic state may serve to maintain cardiac progenitor potential. Consistent with this proposal, the adult epicardium has been shown to contain a reservoir of quiescent cardiac progenitors that are activated in response to heart injury and are hypoxic by comparison to adjacent cardiac tissues. In this review, we discuss the development and potential of the adult epicardium and how this knowledge may provide future therapeutic approaches for cardiac repair.
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Yang T, Yu L, Jin Q, Wu L, He B. Localization of Origins of Premature Ventricular Contraction by Means of Convolutional Neural Network From 12-Lead ECG. IEEE Trans Biomed Eng 2018; 65:1662-1671. [PMID: 28952932 PMCID: PMC6089373 DOI: 10.1109/tbme.2017.2756869] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE This paper proposes a novel method to localize origins of premature ventricular contractions (PVCs) from 12-lead electrocardiography (ECG) using convolutional neural network (CNN) and a realistic computer heart model. METHODS The proposed method consists of two CNNs (Segment CNN and Epi-Endo CNN) to classify among ventricular sources from 25 segments and from epicardium (Epi) or endocardium (Endo). The inputs are the full time courses and the first half of QRS complexes of 12-lead ECG, respectively. After registering the ventricle computer model with an individual patient's heart, the training datasets were generated by multiplying ventricular current dipoles derived from single pacing at various locations with patient-specific lead field. The origins of PVC are localized by calculating the weighted center of gravity of classification returned by the CNNs. A number of computer simulations were conducted to evaluate the proposed method under a variety of noise levels and heart registration errors. Furthermore, the proposed method was evaluated on 90 PVC beats from nine human patients with PVCs and compared against ablation outcome in the same patients. RESULTS The computer simulation evaluation returned relatively high accuracies for Segment CNN (∼78%) and Epi-Endo CNN (∼90%). Clinical testing in nine PVC patients resulted an averaged localization error of 11 mm. CONCLUSION Our simulation and clinical evaluation results demonstrate the capability and merits of the proposed CNN-based method for localization of PVC. SIGNIFICANCE This paper suggests a new approach for cardiac source localization of origin of arrhythmias using only the 12-lead ECG by means of CNN, and may have important applications for future real-time monitoring and localizing origins of cardiac arrhythmias guiding ablation treatment.
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Hojo R, Fukamizu S, Miyazawa S, Kawamura I. High-resolution 3D mapping of epicardial conduction during Marshall bundle-related atrial tachycardia. J Arrhythm 2018; 34:298-301. [PMID: 29951148 PMCID: PMC6009767 DOI: 10.1002/joa3.12067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 04/06/2018] [Indexed: 11/09/2022] Open
Abstract
A 73-year-old woman was admitted for atrial tachycardia (AT) ablation. The activation map and pacing study indicated that the AT propagated around the left pulmonary vein and that the Marshall bundle (MB) bypassed the scar area of the left pulmonary vein ridge and mitral isthmus. The Rhythmia Mapping System revealed double potentials propagated along the assumed position of the MB. The mapping system includes a confidence mask that can be used to visually identify low-confidence areas of the map based upon extremely low-voltage signals. Given the low-voltage area in the endocardial side, the epicardial conduction was emphasized.
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Hippo Signaling Plays an Essential Role in Cell State Transitions during Cardiac Fibroblast Development. Dev Cell 2018; 45:153-169.e6. [PMID: 29689192 DOI: 10.1016/j.devcel.2018.03.019] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 02/02/2018] [Accepted: 03/26/2018] [Indexed: 12/14/2022]
Abstract
During development, progenitors progress through transition states. The cardiac epicardium contains progenitors of essential non-cardiomyocytes. The Hippo pathway, a kinase cascade that inhibits the Yap transcriptional co-factor, controls organ size in developing hearts. Here, we investigated Hippo kinases Lats1 and Lats2 in epicardial diversification. Epicardial-specific deletion of Lats1/2 was embryonic lethal, and mutant embryos had defective coronary vasculature remodeling. Single-cell RNA sequencing revealed that Lats1/2 mutant cells failed to activate fibroblast differentiation but remained in an intermediate cell state with both epicardial and fibroblast characteristics. Lats1/2 mutant cells displayed an arrested developmental trajectory with persistence of epicardial markers and expanded expression of Yap targets Dhrs3, an inhibitor of retinoic acid synthesis, and Dpp4, a protease that modulates extracellular matrix (ECM) composition. Genetic and pharmacologic manipulation revealed that Yap inhibits fibroblast differentiation, prolonging a subepicardial-like cell state, and promotes expression of matricellular factors, such as Dpp4, that define ECM characteristics.
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Messadi M, Bessaid A, Mariano-Goulart D, Bouallègue FB. Development and clinical validation of a hybrid method for semiautomated left ventricle endocardial and epicardial boundary extraction on cine-magnetic resonance images. J Med Imaging (Bellingham) 2018; 5:024002. [PMID: 29662919 DOI: 10.1117/1.jmi.5.2.024002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 03/19/2018] [Indexed: 11/14/2022] Open
Abstract
We describe a hybrid method for left ventricle (LV) endocardial and epicardial segmentation on cardiac magnetic resonance (CMR) images requiring minimal operator intervention. Endocardium extraction results from the union of three independent estimations based on adaptive thresholding, region growing, and active contour with Chan-Vese energy function. Epicardium segmentation relies on conditional morphological dilation of the endocardial mask followed by active contour optimization. The proposed method was first evaluated using an open access database of 18 CMR for which expert manual contouring was available. The method was further validated on a retrospective cohort of 29 patients, who underwent CMR with expert manual segmentation. Regarding the open access database, similarity (Dice index) between hybrid and expert segmentations was good for end-diastolic (ED) endocardium (0.92), end-systolic (ES) endocardium (0.88), and ED epicardium (0.92). As for derived LV parameters, concordance (Lin's coefficient) was good for ED volume (0.91), ES volume (0.93), ejection fraction (EF; 0.89), and fair for myocardial mass (MM; 0.74). Regarding the retrospective patient study, concordance between expert and hybrid estimations was excellent for ED volume (0.95), ES volume (0.96), good for EF (0.86), and fair for MM (0.71). Hybrid segmentation resulted in small biases ([Formula: see text] for ED volume, [Formula: see text] for ES volume, [Formula: see text] for EF, and [Formula: see text] for MM) with little clinical relevance and acceptable for routine practice. The quickness and robustness of the proposed hybrid method and its ability to provide LV volumes, functions, and masses highly concordant with those given by expert segmentation support its pertinence for routine clinical use.
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Becker M, Maring JA, Schneider M, Herrera Martin AX, Seifert M, Klein O, Braun T, Falk V, Stamm C. Towards a Novel Patch Material for Cardiac Applications: Tissue-Specific Extracellular Matrix Introduces Essential Key Features to Decellularized Amniotic Membrane. Int J Mol Sci 2018; 19:E1032. [PMID: 29596384 PMCID: PMC5979550 DOI: 10.3390/ijms19041032] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 03/26/2018] [Accepted: 03/27/2018] [Indexed: 12/18/2022] Open
Abstract
There is a growing need for scaffold material with tissue-specific bioactivity for use in regenerative medicine, tissue engineering, and for surgical repair of structural defects. We developed a novel composite biomaterial by processing human cardiac extracellular matrix (ECM) into a hydrogel and combining it with cell-free amniotic membrane via a dry-coating procedure. Cardiac biocompatibility and immunogenicity were tested in vitro using human cardiac fibroblasts, epicardial progenitor cells, murine HL-1 cells, and human immune cells derived from buffy coat. Processing of the ECM preserved important matrix proteins as demonstrated by mass spectrometry. ECM coating did not alter the mechanical characteristics of decellularized amniotic membrane but did cause a clear increase in adhesion capacity, cell proliferation and viability. Activated monocytes secreted less pro-inflammatory cytokines, and both macrophage polarization towards the pro-inflammatory M1 type and T cell proliferation were prevented. We conclude that the incorporation of human cardiac ECM hydrogel shifts and enhances the bioactivity of decellularized amniotic membrane, facilitating its use in future cardiac applications.
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Kirejczyk SG, Burnum AL, Brown CC, Sakamoto K, Rissi DR. Cardiac mesothelial papillary hyperplasia in four dogs. J Vet Diagn Invest 2018; 30:479-482. [PMID: 29322883 DOI: 10.1177/1040638717753964] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Mesothelial papillary hyperplasia (MPH) has been described as an incidental finding on the epicardial surface of clinically normal laboratory Beagle dogs. We describe MPH in 4 dogs diagnosed with acute cardiac tamponade (1 case) or chronic cardiac disease (3 cases). Cardiac MPH appeared as distinct, soft, irregular villous plaques on the epicardial surface of the auricles and occasionally the ventricles. Histologically, areas of MPH were composed of multiple papillary fronds arising from the epicardial surface and projecting into the pericardial space. Fronds were covered by cuboidal and occasionally vacuolated mesothelial cells and were supported by loose fibrovascular stroma with various degrees of edema and inflammation. Although these may represent incidental findings with no clinical significance, the gross appearance warrants differentiation from other conditions. Additional insight into the pathogenesis of MPH is needed to fully understand its significance in the face of concurrent cardiac disease.
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Cao J, Wang J, Jackman CP, Cox AH, Trembley MA, Balowski JJ, Cox BD, De Simone A, Dickson AL, Di Talia S, Small EM, Kiehart DP, Bursac N, Poss KD. Tension Creates an Endoreplication Wavefront that Leads Regeneration of Epicardial Tissue. Dev Cell 2017; 42:600-615.e4. [PMID: 28950101 DOI: 10.1016/j.devcel.2017.08.024] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/24/2017] [Accepted: 08/29/2017] [Indexed: 01/02/2023]
Abstract
Mechanisms that control cell-cycle dynamics during tissue regeneration require elucidation. Here we find in zebrafish that regeneration of the epicardium, the mesothelial covering of the heart, is mediated by two phenotypically distinct epicardial cell subpopulations. These include a front of large, multinucleate leader cells, trailed by follower cells that divide to produce small, mononucleate daughters. By using live imaging of cell-cycle dynamics, we show that leader cells form by spatiotemporally regulated endoreplication, caused primarily by cytokinesis failure. Leader cells display greater velocities and mechanical tension within the epicardial tissue sheet, and experimentally induced tension anisotropy stimulates ectopic endoreplication. Unbalancing epicardial cell-cycle dynamics with chemical modulators indicated autonomous regenerative capacity in both leader and follower cells, with leaders displaying an enhanced capacity for surface coverage. Our findings provide evidence that mechanical tension can regulate cell-cycle dynamics in regenerating tissue, stratifying the source cell features to improve repair.
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Bao X, Bhute VJ, Han T, Qian T, Lian X, Palecek SP. Human pluripotent stem cell-derived epicardial progenitors can differentiate to endocardial-like endothelial cells. Bioeng Transl Med 2017; 2:191-201. [PMID: 29170757 PMCID: PMC5675097 DOI: 10.1002/btm2.10062] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
During heart development, epicardial progenitors contribute various cardiac lineages including smooth muscle cells, cardiac fibroblasts, and endothelial cells. However, their specific contribution to the human endothelium has not yet been resolved, at least in part due to the inability to expand and maintain human primary or pluripotent stem cell (hPSC)‐derived epicardial cells. Here we first generated CDH5‐2A‐eGFP knock‐in hPSC lines and differentiated them into self‐renewing WT1+ epicardial cells, which gave rise to endothelial cells upon VEGF treatment in vitro. In addition, we found that the percentage of endothelial cells correlated with WT1 expression in a WT1‐2A‐eGFP reporter line. The resulting endothelial cells displayed many endocardium‐like endothelial cell properties, including high expression levels of endocardial‐specific markers, nutrient transporters and well‐organized tight junctions. These findings suggest that human epicardial progenitors may have the capacity to form endocardial endothelium during development and have implications for heart regeneration and cardiac tissue engineering.
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Sugimoto K, Hui SP, Sheng DZ, Kikuchi K. Dissection of zebrafish shha function using site-specific targeting with a Cre-dependent genetic switch. eLife 2017; 6. [PMID: 28513431 PMCID: PMC5435461 DOI: 10.7554/elife.24635] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 05/04/2017] [Indexed: 11/25/2022] Open
Abstract
Despite the extensive use of zebrafish as a model organism in developmental biology and regeneration research, genetic techniques enabling conditional analysis of gene function are limited. In this study, we generated Zwitch, a Cre-dependent invertible gene-trap cassette, enabling the establishment of conditional alleles in zebrafish by generating intronic insertions via in vivo homologous recombination. To demonstrate the utility of Zwitch, we generated a conditional sonic hedgehog a (shha) allele. Homozygous shha mutants developed normally; however, shha mutant embryos globally expressing Cre exhibited strong reductions in endogenous shha and shha target gene mRNA levels and developmental defects associated with null shha mutations. Analyzing a conditional shha mutant generated using an epicardium-specific inducible Cre driver revealed unique roles for epicardium-derived Shha in myocardial proliferation during heart development and regeneration. Zwitch will extend the utility of zebrafish in organ development and regeneration research and might be applicable to other model organisms. DOI:http://dx.doi.org/10.7554/eLife.24635.001
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Dueñas A, Aranega AE, Franco D. More than Just a Simple Cardiac Envelope; Cellular Contributions of the Epicardium. Front Cell Dev Biol 2017; 5:44. [PMID: 28507986 PMCID: PMC5410615 DOI: 10.3389/fcell.2017.00044] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/10/2017] [Indexed: 12/12/2022] Open
Abstract
The adult pumping heart is formed by distinct tissue layers. From inside to outside, the heart is composed by an internal endothelial layer, dubbed the endocardium, a thick myocardial component which supports the pumping capacity of the heart and exteriorly covered by a thin mesothelial layer named the epicardium. Cardiac insults such as coronary artery obstruction lead to ischemia and thus to an irreversible damage of the myocardial layer, provoking in many cases heart failure and death. Thus, searching for new pathways to regenerate the myocardium is an urgent biomedical need. Interestingly, the capacity of heart regeneration is present in other species, ranging from fishes to neonatal mammals. In this context, several lines of evidences demonstrated a key regulatory role for the epicardial layer. In this manuscript, we provide a state-of-the-art review on the developmental process leading to the formation of the epicardium, the distinct pathways controlling epicardial precursor cell specification and determination and current evidences on the regenerative potential of the epicardium to heal the injured heart.
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Wang QL, Wang HJ, Li ZH, Wang YL, Wu XP, Tan YZ. Mesenchymal stem cell-loaded cardiac patch promotes epicardial activation and repair of the infarcted myocardium. J Cell Mol Med 2017; 21:1751-1766. [PMID: 28244640 PMCID: PMC5571540 DOI: 10.1111/jcmm.13097] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 12/21/2016] [Indexed: 01/13/2023] Open
Abstract
Cardiac patch is considered a promising strategy for enhancing stem cell therapy of myocardial infarction (MI). However, the underlying mechanisms for cardiac patch repairing infarcted myocardium remain unclear. In this study, we investigated the mechanisms of PCL/gelatin patch loaded with MSCs on activating endogenous cardiac repair. PCL/gelatin patch was fabricated by electrospun. The patch enhanced the survival of the seeded MSCs and their HIF-1α, Tβ4, VEGF and SDF-1 expression and decreased CXCL14 expression in hypoxic and serum-deprived conditions. In murine MI models, the survival and distribution of the engrafted MSCs and the activation of the epicardium were examined, respectively. At 4 weeks after transplantation of the cell patch, the cardiac functions were significantly improved. The engrafted MSCs migrated across the epicardium and into the myocardium. Tendency of HIF-1α, Tβ4, VEGF, SDF-1 and CXCL14 expression in the infarcted myocardium was similar with expression in vitro. The epicardium was activated and epicardial-derived cells (EPDCs) migrated into deep tissue. The EPDCs differentiated into endothelial cells and smooth muscle cells, and some of EPDCs showed to have differentiated into cardiomyocytes. Density of blood and lymphatic capillaries increased significantly. More c-kit+ cells were recruited into the infarcted myocardium after transplantation of the cell patch. The results suggest that epicardial transplantation of the cell patch promotes repair of the infarcted myocardium and improves cardiac functions by enhancing the survival of the transplanted cells, accelerating locality paracrine, and then activating the epicardium and recruiting endogenous c-kit+ cells. Epicardial transplantation of the cell patch may be applied as a novel effective MI therapy.
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Nagase S, Tanaka M, Morita H, Nakagawa K, Wada T, Murakami M, Nishii N, Nakamura K, Ito H, Ohe T, Kusano KF. Local Left Ventricular Epicardial J Waves and Late Potentials in Brugada Syndrome Patients with Inferolateral Early Repolarization Pattern. Front Physiol 2017; 8:14. [PMID: 28184198 PMCID: PMC5266732 DOI: 10.3389/fphys.2017.00014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 01/09/2017] [Indexed: 01/27/2023] Open
Abstract
Background: Brugada syndrome (BrS) is characterized by J-point or ST-segment elevation on electrocardiograms (ECGs) and increased risk of ventricular fibrillation (VF). In BrS, epicardial depolarization abnormality with delayed potential on the right ventricular outflow tract is reportedly the predominant mechanism underlying VF. Yet VF occurrence is also associated with early repolarization (ER) pattern in the inferolateral ECG leads, which may represent the inferior and/or left lateral ventricular myocardium. The aim of this study was to examine epicardial electrograms recorded directly at the left ventricle (LV) in BrS patients after VF episodes. Methods: In 12 BrS patients who had experienced VF episodes and 17 control subjects, a multipolar catheter was introduced into the left lateral coronary vein for unipolar and bipolar electrogram recordings at the LV epicardium. Both inferior and lateral ER patterns on ECG were observed in three BrS patients and six control subjects. Results: In the epicardium, prominent J waves were detected using unipolar recording, and potentials after the QRS complex were detected using bipolar recording in three of the 12 BrS patients. These three patients also showed both inferior and lateral ER patterns on ECG. Neither prominent J waves nor potentials after the QRS complex were recorded at the endocardium of the LV in any of these three patients; nor were they seen at the epicardium in any of the control subjects. These features were accentuated on pilsicainide administration (n = 2) but diminished on constant atrial pacing (n = 3) and isoproterenol administration (n = 1). The J waves observed through unipolar recording coincided with the potentials after QRS complex observed through bipolar recording and with the inferolateral ER patterns on ECG. Conclusions: We recorded prominent J waves in unipolar electrogram and potentials after QRS complex in bipolar electrogram at the LV epicardium in BrS patients with global ER pattern. The prominent J waves coincided with the potentials after QRS complex and the inferolateral ER pattern on ECG. The characteristics of the inferolateral ER pattern on ECG in these patients primarily represent depolarization feature.
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Abstract
The hearts of lower vertebrates such as fish and salamanders display scarless regeneration following injury, although this feature is lost in adult mammals. The remarkable capacity of the neonatal mammalian heart to regenerate suggests that the underlying machinery required for the regenerative process is evolutionarily retained. Recent studies highlight the epicardial covering of the heart as an important source of the signalling factors required for the repair process. The developing epicardium is also a major source of cardiac fibroblasts, smooth muscle, endothelial cells and stem cells. Here, we examine animal models that are capable of scarless regeneration, the role of the epicardium as a source of cells, signalling mechanisms implicated in the regenerative process and how these mechanisms influence cardiomyocyte proliferation. We also discuss recent advances in cardiac stem cell research and potential therapeutic targets arising from these studies.
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Rudic B, Chaykovskaya M, Tsyganov A, Kalinin V, Tülümen E, Papavassiliu T, Dösch C, Liebe V, Kuschyk J, Röger S, El-Battrawy I, Akin I, Yakovleva M, Zaklyazminskaya E, Shestak A, Kim S, Chmelevsky M, Borggrefe M. Simultaneous Non-Invasive Epicardial and Endocardial Mapping in Patients With Brugada Syndrome: New Insights Into Arrhythmia Mechanisms. J Am Heart Assoc 2016; 5:JAHA.116.004095. [PMID: 27930354 PMCID: PMC5210320 DOI: 10.1161/jaha.116.004095] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Background The underlying mechanisms of Brugada syndrome (BrS) are not completely understood. Recent studies provided evidence that the electrophysiological substrate, leading to electrocardiogram abnormalities and/or ventricular arrhythmias, is located in the right ventricular outflow tract (RVOT). The purpose of this study was to examine abnormalities of epicardial and endocardial local unipolar electrograms by simultaneous noninvasive mapping in patients with BrS. Methods and Results Local epicardial and endocardial unipolar electrograms were analyzed using a novel noninvasive epi‐ and endocardial electrophysiology system (NEEES) in 12 patients with BrS and 6 with right bundle branch block for comparison. Fifteen normal subjects composed the control group. Observed depolarization abnormalities included fragmented electrograms in the anatomical area of RVOT endocardially and epicardially, significantly prolonged activation time in the RVOT endocardium (65±20 vs 38±13 ms in controls; P=0.008), prolongation of the activation‐recovery interval in the RVOT epicardium (281±34 vs 247±26 ms in controls; P=0.002). Repolarization abnormalities included a larger area of ST‐segment elevation >2 mV and T‐wave inversions. Negative voltage gradient (−2.5 to −6.0 mV) between epicardium and endocardium of the RVOT was observed in 8 of 12 BrS patients, not present in patients with right bundle branch block or in controls. Conclusions Abnormalities of epicardial and endocardial electrograms associated with depolarization and repolarization properties were found using NEEES exclusively in the RVOT of BrS patients. These findings support both, depolarization and repolarization abnormalities, being operative at the same time in patients with BrS.
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Zangi L, Oliveira MS, Ye LY, Ma Q, Sultana N, Hadas Y, Chepurko E, Später D, Zhou B, Chew WL, Ebina W, Abrial M, Wang QD, Pu WT, Chien KR. Insulin-Like Growth Factor 1 Receptor-Dependent Pathway Drives Epicardial Adipose Tissue Formation After Myocardial Injury. Circulation 2016; 135:59-72. [PMID: 27803039 DOI: 10.1161/circulationaha.116.022064] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/08/2016] [Indexed: 11/16/2022]
Abstract
BACKGROUND Epicardial adipose tissue volume and coronary artery disease are strongly associated, even after accounting for overall body mass. Despite its pathophysiological significance, the origin and paracrine signaling pathways that regulate epicardial adipose tissue's formation and expansion are unclear. METHODS We used a novel modified mRNA-based screening approach to probe the effect of individual paracrine factors on epicardial progenitors in the adult heart. RESULTS Using 2 independent lineage-tracing strategies in murine models, we show that cells originating from the Wt1+ mesothelial lineage, which includes epicardial cells, differentiate into epicardial adipose tissue after myocardial infarction. This differentiation process required Wt1 expression in this lineage and was stimulated by insulin-like growth factor 1 receptor (IGF1R) activation. IGF1R inhibition within this lineage significantly reduced its adipogenic differentiation in the context of exogenous, IGF1-modified mRNA stimulation. Moreover, IGF1R inhibition significantly reduced Wt1 lineage cell differentiation into adipocytes after myocardial infarction. CONCLUSIONS Our results establish IGF1R signaling as a key pathway that governs epicardial adipose tissue formation in the context of myocardial injury by redirecting the fate of Wt1+ lineage cells. Our study also demonstrates the power of modified mRNA -based paracrine factor library screening to dissect signaling pathways that govern progenitor cell activity in homeostasis and disease.
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Yamada T, Lloyd SG, Yoshida N, Kay GN. Double-Layer Separate Ventricular Activation Patterns During Ventricular Tachycardia Associated With Myocarditis. Circ Arrhythm Electrophysiol 2016; 9:CIRCEP.116.004345. [PMID: 27729346 DOI: 10.1161/circep.116.004345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 07/06/2016] [Indexed: 11/16/2022]
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Calderon D, Bardot E, Dubois N. Probing early heart development to instruct stem cell differentiation strategies. Dev Dyn 2016; 245:1130-1144. [PMID: 27580352 DOI: 10.1002/dvdy.24441] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 08/20/2016] [Accepted: 08/20/2016] [Indexed: 12/19/2022] Open
Abstract
Scientists have studied organs and their development for centuries and, along that path, described models and mechanisms explaining the developmental principles of organogenesis. In particular, with respect to the heart, new fundamental discoveries are reported continuously that keep changing the way we think about early cardiac development. These discoveries are driven by the need to answer long-standing questions regarding the origin of the earliest cells specified to the cardiac lineage, the differentiation potential of distinct cardiac progenitor cells, and, very importantly, the molecular mechanisms underlying these specification events. As evidenced by numerous examples, the wealth of developmental knowledge collected over the years has had an invaluable impact on establishing efficient strategies to generate cardiovascular cell types ex vivo, from either pluripotent stem cells or via direct reprogramming approaches. The ability to generate functional cardiovascular cells in an efficient and reliable manner will contribute to therapeutic strategies aimed at alleviating the increasing burden of cardiovascular disease and morbidity. Here we will discuss the recent discoveries in the field of cardiac progenitor biology and their translation to the pluripotent stem cell model to illustrate how developmental concepts have instructed regenerative model systems in the past and promise to do so in the future. Developmental Dynamics 245:1130-1144, 2016. © 2016 Wiley Periodicals, Inc.
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Hippo Signaling Mediators Yap and Taz Are Required in the Epicardium for Coronary Vasculature Development. Cell Rep 2016; 15:1384-1393. [PMID: 27160901 DOI: 10.1016/j.celrep.2016.04.027] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 03/02/2016] [Accepted: 04/02/2016] [Indexed: 02/08/2023] Open
Abstract
Formation of the coronary vasculature is a complex and precisely coordinated morphogenetic process that begins with the formation of epicardium. The epicardium gives rise to many components of the coronary vasculature, including fibroblasts, smooth muscle cells, and endothelium. Hippo signaling components have been implicated in cardiac development and regeneration. However, a role of Hippo signaling in the epicardium has not been explored. Employing a combination of genetic and pharmacological approaches, we demonstrate that inhibition of Hippo signaling mediators Yap and Taz leads to impaired epicardial epithelial-to-mesenchymal transition (EMT) and a reduction in epicardial cell proliferation and differentiation into coronary endothelial cells. We provide evidence that Yap and Taz control epicardial cell behavior, in part by regulating Tbx18 and Wt1 expression. Our findings show a role for Hippo signaling in epicardial cell proliferation, EMT, and cell fate specification during cardiac organogenesis.
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