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Boulgakoff L, D'Amato G, Miquerol L. Molecular Regulation of Cardiac Conduction System Development. Curr Cardiol Rep 2024:10.1007/s11886-024-02094-7. [PMID: 38990492 DOI: 10.1007/s11886-024-02094-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/02/2024] [Indexed: 07/12/2024]
Abstract
PURPOSE OF REVIEW The cardiac conduction system, composed of pacemaker cells and conducting cardiomyocytes, orchestrates the propagation of electrical activity to synchronize heartbeats. The conduction system plays a crucial role in the development of cardiac arrhythmias. In the embryo, the cells of the conduction system derive from the same cardiac progenitors as the contractile cardiomyocytes and and the key question is how this choice is made during development. RECENT FINDINGS This review focuses on recent advances in developmental biology using the mouse as animal model to better understand the cellular origin and molecular regulations that control morphogenesis of the cardiac conduction system, including the latest findings in single-cell transcriptomics. The conducting cell fate is acquired during development starting with pacemaking activity and last with the formation of a complex fast-conducting network. Cardiac conduction system morphogenesis is controlled by complex transcriptional and gene regulatory networks that differ in the components of the cardiac conduction system.
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Affiliation(s)
| | - Gaetano D'Amato
- Aix-Marseille Université, CNRS IBDM UMR7288, Marseille, France
| | - Lucile Miquerol
- Aix-Marseille Université, CNRS IBDM UMR7288, Marseille, France.
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2
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Lee C, Xu S, Samad T, Goodyer WR, Raissadati A, Heinrich P, Wu SM. The cardiac conduction system: History, development, and disease. Curr Top Dev Biol 2024; 156:157-200. [PMID: 38556422 DOI: 10.1016/bs.ctdb.2024.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
The heart is the first organ to form during embryonic development, establishing the circulatory infrastructure necessary to sustain life and enable downstream organogenesis. Critical to the heart's function is its ability to initiate and propagate electrical impulses that allow for the coordinated contraction and relaxation of its chambers, and thus, the movement of blood and nutrients. Several specialized structures within the heart, collectively known as the cardiac conduction system (CCS), are responsible for this phenomenon. In this review, we discuss the discovery and scientific history of the mammalian cardiac conduction system as well as the key genes and transcription factors implicated in the formation of its major structures. We also describe known human diseases related to CCS development and explore existing challenges in the clinical context.
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Affiliation(s)
- Carissa Lee
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States
| | - Sidra Xu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States
| | - Tahmina Samad
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Division of Pediatric Cardiology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, United States; Department of Pediatrics, Stanford University, Stanford, CA, United States
| | - William R Goodyer
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Division of Pediatric Cardiology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, United States
| | - Alireza Raissadati
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Division of Pediatric Cardiology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, United States
| | - Paul Heinrich
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Regenerative Medicine in Cardiovascular Diseases, First Department of Medicine, Cardiology, Klinikum Rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
| | - Sean M Wu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, United States; Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, CA, United States.
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3
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Prodan N, Ershad F, Reyes-Alcaraz A, Li L, Mistretta B, Gonzalez L, Rao Z, Yu C, Gunaratne PH, Li N, Schwartz RJ, McConnell BK. Direct reprogramming of cardiomyocytes into cardiac Purkinje-like cells. iScience 2022; 25:105402. [PMID: 36388958 PMCID: PMC9646947 DOI: 10.1016/j.isci.2022.105402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 09/30/2022] [Accepted: 10/14/2022] [Indexed: 11/06/2022] Open
Abstract
Currently, there are no treatments that ameliorate cardiac cell death, the underlying basis of cardiovascular disease. An unexplored cell type in cardiac regeneration is cardiac Purkinje cells; specialized cells from the cardiac conduction system (CCS) responsible for propagating electrical signals. Purkinje cells have tremendous potential as a regenerative treatment because they may intrinsically integrate with the CCS of a recipient myocardium, resulting in more efficient electrical conduction in diseased hearts. This study is the first to demonstrate an effective protocol for the direct reprogramming of human cardiomyocytes into cardiac Purkinje-like cells using small molecules. The cells generated were genetically and functionally similar to native cardiac Purkinje cells, where expression of key cardiac Purkinje genes such as CNTN2, ETV1, PCP4, IRX3, SCN5a, HCN2 and the conduction of electrical signals with increased velocity was observed. This study may help to advance the quest to finding an optimized cell therapy for heart regeneration.
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Affiliation(s)
- Nicole Prodan
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, 4349 Martin Luther King Blvd, Health-2 (H2) Building, Room 5024, Houston, TX 77204-5037, USA
| | - Faheem Ershad
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
| | - Arfaxad Reyes-Alcaraz
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, 4349 Martin Luther King Blvd, Health-2 (H2) Building, Room 5024, Houston, TX 77204-5037, USA
| | - Luge Li
- Department of Medicine (Section of Cardiovascular Research), Baylor College of Medicine, Houston, TX 77030, USA
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Brandon Mistretta
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
- Department of Biology and Biochemistry, UH-Sequencing & Gene Editing Core, University of Houston, Houston, TX 77204, USA
| | - Lei Gonzalez
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
| | - Zhoulyu Rao
- Department of Mechanical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
| | - Cunjiang Yu
- Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
- Department of Mechanical Engineering, Cullen College of Engineering, University of Houston, Houston, TX 77204, USA
| | - Preethi H. Gunaratne
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
- Department of Biology and Biochemistry, UH-Sequencing & Gene Editing Core, University of Houston, Houston, TX 77204, USA
| | - Na Li
- Department of Medicine (Section of Cardiovascular Research), Baylor College of Medicine, Houston, TX 77030, USA
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Robert J. Schwartz
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
| | - Bradley K. McConnell
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, 4349 Martin Luther King Blvd, Health-2 (H2) Building, Room 5024, Houston, TX 77204-5037, USA
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
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4
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Wang L, Bhakta M, Fernandez-Perez A, Munshi NV. Inducible cardiomyocyte injury within the atrioventricular conduction system uncovers latent regenerative capacity in mice. J Clin Invest 2021; 131:138637. [PMID: 34596051 DOI: 10.1172/jci138637] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 08/05/2021] [Indexed: 11/17/2022] Open
Abstract
The cardiac conduction system (CCS) ensures regular contractile function, and injury to any of its components can cause cardiac dysrhythmia. Although all cardiomyocytes (CMs) originate from common progenitors, the CCS is composed of biologically distinct cell types with unique functional and developmental characteristics. In contrast to ventricular cardiomyocytes, which continue to proliferate after birth, most CCS cells terminally exit the cell cycle during fetal development. Although the CCS should thus provide a poor substrate for postnatal injury repair, its regenerative capacity remains untested. Here, we describe a genetic system for ablating CMs that reside within the atrioventricular conduction system (AVCS). Adult mouse AVCS ablation resulted in regenerative failure characterized by persistent atrioventricular conduction defects and contractile dysfunction. In contrast, AVCS injury in neonatal mice led to recovery in a subset of these mice, thus providing evidence for CCS plasticity. Furthermore, CM proliferation did not appear to completely account for the observed functional recovery, suggesting that mechanisms regulating recovery from dysrhythmia are likely to be distinct from cardiac regeneration associated with ventricular injury. Taken together, we anticipate that our results will motivate further mechanistic studies of CCS plasticity and enable the exploration of rhythm restoration as an alternative therapeutic strategy.
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Affiliation(s)
- Lin Wang
- Department of Internal Medicine (Cardiology Division)
| | - Minoti Bhakta
- Department of Internal Medicine (Cardiology Division)
| | | | - Nikhil V Munshi
- Department of Internal Medicine (Cardiology Division).,Department of Molecular Biology.,McDermott Center for Human Growth and Development, and.,Center for Regenerative Science and Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
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5
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New Insights into the Development and Morphogenesis of the Cardiac Purkinje Fiber Network: Linking Architecture and Function. J Cardiovasc Dev Dis 2021; 8:jcdd8080095. [PMID: 34436237 PMCID: PMC8397066 DOI: 10.3390/jcdd8080095] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/30/2021] [Accepted: 08/03/2021] [Indexed: 12/30/2022] Open
Abstract
The rapid propagation of electrical activity through the ventricular conduction system (VCS) controls spatiotemporal contraction of the ventricles. Cardiac conduction defects or arrhythmias in humans are often associated with mutations in key cardiac transcription factors that have been shown to play important roles in VCS morphogenesis in mice. Understanding of the mechanisms of VCS development is thus crucial to decipher the etiology of conduction disturbances in adults. During embryogenesis, the VCS, consisting of the His bundle, bundle branches, and the distal Purkinje network, originates from two independent progenitor populations in the primary ring and the ventricular trabeculae. Differentiation into fast-conducting cardiomyocytes occurs progressively as ventricles develop to form a unique electrical pathway at late fetal stages. The objectives of this review are to highlight the structure–function relationship between VCS morphogenesis and conduction defects and to discuss recent data on the origin and development of the VCS with a focus on the distal Purkinje fiber network.
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6
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Olejnickova V, Kocka M, Kvasilova A, Kolesova H, Dziacky A, Gidor T, Gidor L, Sankova B, Gregorovicova M, Gourdie RG, Sedmera D. Gap Junctional Communication via Connexin43 between Purkinje Fibers and Working Myocytes Explains the Epicardial Activation Pattern in the Postnatal Mouse Left Ventricle. Int J Mol Sci 2021; 22:2475. [PMID: 33804428 PMCID: PMC7957598 DOI: 10.3390/ijms22052475] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/19/2021] [Accepted: 02/25/2021] [Indexed: 12/31/2022] Open
Abstract
The mammalian ventricular myocardium forms a functional syncytium due to flow of electrical current mediated in part by gap junctions localized within intercalated disks. The connexin (Cx) subunit of gap junctions have direct and indirect roles in conduction of electrical impulse from the cardiac pacemaker via the cardiac conduction system (CCS) to working myocytes. Cx43 is the dominant isoform in these channels. We have studied the distribution of Cx43 junctions between the CCS and working myocytes in a transgenic mouse model, which had the His-Purkinje portion of the CCS labeled with green fluorescence protein. The highest number of such connections was found in a region about one-third of ventricular length above the apex, and it correlated with the peak proportion of Purkinje fibers (PFs) to the ventricular myocardium. At this location, on the septal surface of the left ventricle, the insulated left bundle branch split into the uninsulated network of PFs that continued to the free wall anteriorly and posteriorly. The second peak of PF abundance was present in the ventricular apex. Epicardial activation maps correspondingly placed the site of the first activation in the apical region, while some hearts presented more highly located breakthrough sites. Taken together, these results increase our understanding of the physiological pattern of ventricular activation and its morphological underpinning through detailed CCS anatomy and distribution of its gap junctional coupling to the working myocardium.
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Affiliation(s)
- Veronika Olejnickova
- Institute of Anatomy, First Faculty of Medicine, Charles University, 128 00 Prague, Czech Republic; (V.O.); (M.K.); (A.K.); (H.K.); (A.D.); (T.G.); (L.G.); (B.S.); (M.G.)
- Institute of Physiology, CAS, 142 20 Prague, Czech Republic
| | - Matej Kocka
- Institute of Anatomy, First Faculty of Medicine, Charles University, 128 00 Prague, Czech Republic; (V.O.); (M.K.); (A.K.); (H.K.); (A.D.); (T.G.); (L.G.); (B.S.); (M.G.)
| | - Alena Kvasilova
- Institute of Anatomy, First Faculty of Medicine, Charles University, 128 00 Prague, Czech Republic; (V.O.); (M.K.); (A.K.); (H.K.); (A.D.); (T.G.); (L.G.); (B.S.); (M.G.)
| | - Hana Kolesova
- Institute of Anatomy, First Faculty of Medicine, Charles University, 128 00 Prague, Czech Republic; (V.O.); (M.K.); (A.K.); (H.K.); (A.D.); (T.G.); (L.G.); (B.S.); (M.G.)
- Institute of Physiology, CAS, 142 20 Prague, Czech Republic
| | - Adam Dziacky
- Institute of Anatomy, First Faculty of Medicine, Charles University, 128 00 Prague, Czech Republic; (V.O.); (M.K.); (A.K.); (H.K.); (A.D.); (T.G.); (L.G.); (B.S.); (M.G.)
- Department of Pediatric Cardiology, Motol University Hospital, 150 06 Prague, Czech Republic
| | - Tom Gidor
- Institute of Anatomy, First Faculty of Medicine, Charles University, 128 00 Prague, Czech Republic; (V.O.); (M.K.); (A.K.); (H.K.); (A.D.); (T.G.); (L.G.); (B.S.); (M.G.)
| | - Lihi Gidor
- Institute of Anatomy, First Faculty of Medicine, Charles University, 128 00 Prague, Czech Republic; (V.O.); (M.K.); (A.K.); (H.K.); (A.D.); (T.G.); (L.G.); (B.S.); (M.G.)
| | - Barbora Sankova
- Institute of Anatomy, First Faculty of Medicine, Charles University, 128 00 Prague, Czech Republic; (V.O.); (M.K.); (A.K.); (H.K.); (A.D.); (T.G.); (L.G.); (B.S.); (M.G.)
| | - Martina Gregorovicova
- Institute of Anatomy, First Faculty of Medicine, Charles University, 128 00 Prague, Czech Republic; (V.O.); (M.K.); (A.K.); (H.K.); (A.D.); (T.G.); (L.G.); (B.S.); (M.G.)
- Institute of Physiology, CAS, 142 20 Prague, Czech Republic
| | - Robert G. Gourdie
- Fralin Biomedical Research Institute, Virginia Tech, Roanoke, VA 24016, USA;
| | - David Sedmera
- Institute of Anatomy, First Faculty of Medicine, Charles University, 128 00 Prague, Czech Republic; (V.O.); (M.K.); (A.K.); (H.K.); (A.D.); (T.G.); (L.G.); (B.S.); (M.G.)
- Institute of Physiology, CAS, 142 20 Prague, Czech Republic
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7
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Hendrickson T, Mancino C, Whitney L, Tsao C, Rahimi M, Taraballi F. Mimicking cardiac tissue complexity through physical cues: A review on cardiac tissue engineering approaches. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2021; 33:102367. [PMID: 33549819 DOI: 10.1016/j.nano.2021.102367] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 01/06/2021] [Accepted: 01/15/2021] [Indexed: 02/08/2023]
Abstract
Cardiovascular diseases are the number one killer in the world.1,2 Currently, there are no clinical treatments to regenerate damaged cardiac tissue, leaving patients to develop further life-threatening cardiac complications. Cardiac tissue has multiple functional demands including vascularization, contraction, and conduction that require many synergic components to properly work. Most of these functions are a direct result of the cardiac tissue structure and composition, and, for this reason, tissue engineering strongly proposed to develop substitute engineered heart tissues (EHTs). EHTs usually have combined pluripotent stem cells and supporting scaffolds with the final aim to repair or replace the damaged native tissue. However, as simple as this idea is, indeed, it resulted, after many attempts in the field, to be very challenging. Without design complexity, EHTs remain unable to mature fully and integrate into surrounding heart tissue resulting in minimal in vivo effects.3 Lately, there has been a growing body of evidence that a complex, multifunctional approach through implementing scaffold designs, cellularization, and molecular release appears to be essential in the development of a functional cardiac EHTs.4-6 This review covers the advancements in EHTs developments focusing on how to integrate contraction, conduction, and vascularization mimics and how combinations have resulted in improved designs thus warranting further investigation to develop a clinically applicable treatment.
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Affiliation(s)
- Troy Hendrickson
- Center for Musculoskeletal Regeneration, Houston Methodist Research Institute, Houston Methodist, Houston, TX, USA; Orthopedics and Sports Medicine, Houston Methodist Hospital, Houston, TX, USA; Texas A&M MD/PhD Program, Texas A&M Health Science Center, College Station, TX, USA
| | - Chiara Mancino
- Center for Musculoskeletal Regeneration, Houston Methodist Research Institute, Houston Methodist, Houston, TX, USA; Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano, (MI), Italy
| | - Lauren Whitney
- Texas A&M Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Chris Tsao
- Center for Musculoskeletal Regeneration, Houston Methodist Research Institute, Houston Methodist, Houston, TX, USA
| | - Maham Rahimi
- Department of Cardiovascular Surgery, Houston Methodist, Houston, TX, USA
| | - Francesca Taraballi
- Center for Musculoskeletal Regeneration, Houston Methodist Research Institute, Houston Methodist, Houston, TX, USA; Orthopedics and Sports Medicine, Houston Methodist Hospital, Houston, TX, USA.
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8
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Gyenes DL, McBrien AH, Bohun CM, Serrano-Lomelin J, Alvarez SGV, Howley LW, Savard W, Jain V, Motan T, Atallah J, Hornberger LK. Evolution of the Fetal Atrioventricular Interval from 6 to 40 Weeks of Gestation. Am J Cardiol 2019; 123:1709-1714. [PMID: 30871745 DOI: 10.1016/j.amjcard.2019.02.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 02/06/2019] [Accepted: 02/13/2019] [Indexed: 11/17/2022]
Abstract
Doppler-based methods of estimating the atrioventricular interval are commonly used as a surrogate for the electrical PR in fetuses at risk of conduction abnormalities; however, to date, normal values for the fetal atrioventricular interval and an understanding of the evolution of its components in the late first trimester are lacking. We sought to investigate changes in the fetal atrioventricular interval from the first trimester to 40 weeks gestational age, and to explore functional and electrophysiological events that potentially impact its evolution. We prospectively examined healthy pregnancies by fetal echocardiography from 6 to 40 weeks' gestational age. The atrioventricular interval, heart rate, isovolumic contraction time, and A-wave duration were measured from simultaneous ventricular inflow-outflow Doppler tracings. Regression analysis was used to examine relations with gestational age, and linear relations with heart rate were assessed by Pearson's correlation coefficient. Data were collected in 305 fetuses from 279 pregnancies. Atrioventricular interval demonstrated an inverse relation with heart rate (r = -0.45, p <0.0001), dramatically decreasing before 10 weeks and slowly increasing thereafter. Between 6 and 9 weeks, isovolumic contraction time acutely decreased approaching 0, thereafter minimally increasing to term. In contrast, from 6 weeks, the A-wave duration linearly increased through gestation, and negatively correlated with heart rate (r = -0.62, p <0.0001). In conclusion, we have established normal measures of the atrioventricular interval from 6 to 40 weeks' gestational age. Before 10 weeks, a prolonged atrioventricular interval in healthy fetuses largely reflects the lengthened isovolumic contraction time which is likely influenced by the evolution of ventricular function and afterload.
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Affiliation(s)
- Dora L Gyenes
- Fetal and Neonatal Cardiology Program, Division of Cardiology, Department of Pediatrics, Stollery Children's Hospital, Edmonton, Alberta, Canada; Women's and Children's Health Research Institute and Cardiovascular Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Angela H McBrien
- Fetal and Neonatal Cardiology Program, Division of Cardiology, Department of Pediatrics, Stollery Children's Hospital, Edmonton, Alberta, Canada; Women's and Children's Health Research Institute and Cardiovascular Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - C Monique Bohun
- Department of Pediatrics/Cardiology, The University of New Mexico, Albuquerque, New Mexico
| | - Jesus Serrano-Lomelin
- Women's and Children's Health Research Institute and Cardiovascular Research Institute, University of Alberta, Edmonton, Alberta, Canada; School of Public Health, University of Alberta, Edmonton, Alberta, Canada
| | | | - Lisa W Howley
- The Heart Institute, Children's Hospital Colorado/University of Colorado, Aurora, Colorado
| | - Winnie Savard
- Fetal and Neonatal Cardiology Program, Division of Cardiology, Department of Pediatrics, Stollery Children's Hospital, Edmonton, Alberta, Canada; Women's and Children's Health Research Institute and Cardiovascular Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Venu Jain
- Women's and Children's Health Research Institute and Cardiovascular Research Institute, University of Alberta, Edmonton, Alberta, Canada; Department of Obstetrics and Gynecology, University of Alberta, Edmonton, Alberta, Canada
| | - Tarek Motan
- Department of Obstetrics and Gynecology, University of Alberta, Edmonton, Alberta, Canada
| | - Joseph Atallah
- Fetal and Neonatal Cardiology Program, Division of Cardiology, Department of Pediatrics, Stollery Children's Hospital, Edmonton, Alberta, Canada
| | - Lisa K Hornberger
- Fetal and Neonatal Cardiology Program, Division of Cardiology, Department of Pediatrics, Stollery Children's Hospital, Edmonton, Alberta, Canada; Women's and Children's Health Research Institute and Cardiovascular Research Institute, University of Alberta, Edmonton, Alberta, Canada; Department of Obstetrics and Gynecology, University of Alberta, Edmonton, Alberta, Canada.
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9
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Samal E, Evangelista M, Galang G, Srivastava D, Zhao Y, Vedantham V. Premature MicroRNA-1 Expression Causes Hypoplasia of the Cardiac Ventricular Conduction System. Front Physiol 2019; 10:235. [PMID: 30936836 PMCID: PMC6431665 DOI: 10.3389/fphys.2019.00235] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 02/22/2019] [Indexed: 12/27/2022] Open
Abstract
Mammalian cardiac Purkinje fibers (PFs) are specified from ventricular trabecular myocardium during mid-gestation and undergo limited proliferation before assuming their final form. MicroRNA-1 (miR-1), a negative regulator of proliferation, is normally expressed in the heart at low levels during the period of PF specification and outgrowth, but expression rises steeply after birth, when myocardial proliferation slows and postnatal cardiac maturation and growth commence. Here, we test whether premature up-regulation and overexpression of miR-1 during the period of PF morphogenesis influences PF development and function. Using a mouse model in which miR-1 is expressed under the control of the Myh6 promoter, we demonstrate that premature miR-1 expression leads to PF hypoplasia that persists into adulthood, and miR-1 TG mice exhibit delayed conduction through the ventricular myocardium beginning at neonatal stages. In addition, miR-1 transgenic embryos showed reduced proliferation within the trabecular myocardium and embryonic ventricular conduction system (VCS), a source of progenitor cells for the PF. This repression of proliferation may be mediated by direct translational inhibition by miR-1 of the cyclin dependent kinase Cdk6, a key regulator of embryonic myocardial proliferation. Our results suggest that altering the timing of miR-1 expression can regulate PF development, findings which have implications for our understanding of conduction system development and disease in humans.
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Affiliation(s)
- Eva Samal
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA, United States
| | - Melissa Evangelista
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA, United States.,Department of Medicine, University of California, San Francisco, San Francisco, CA, United States
| | - Giselle Galang
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA, United States.,Department of Medicine, University of California, San Francisco, San Francisco, CA, United States.,Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
| | - Deepak Srivastava
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA, United States.,Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States.,Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, United States.,Department of Pediatrics, University of California, San Francisco, San Francisco, CA, United States
| | - Yong Zhao
- Department of Genetics and Genomic Sciences, Mount Sinai Hospital, New York, NY, United States
| | - Vasanth Vedantham
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA, United States.,Department of Medicine, University of California, San Francisco, San Francisco, CA, United States.,Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, United States
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10
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Goodyer W, Wu SM. Fates Aligned: Origins and Mechanisms of Ventricular Conduction System and Ventricular Wall Development. Pediatr Cardiol 2018; 39:1090-1098. [PMID: 29594502 PMCID: PMC6093793 DOI: 10.1007/s00246-018-1869-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/14/2018] [Indexed: 12/19/2022]
Abstract
The cardiac conduction system is a network of distinct cell types necessary for the coordinated contraction of the cardiac chambers. The distal portion, known as the ventricular conduction system, allows for the rapid transmission of impulses from the atrio-ventricular node to the ventricular myocardium and plays a central role in cardiac function as well as disease when perturbed. Notably, its patterning during embryogenesis is intimately linked to that of ventricular wall formation, including trabeculation and compaction. Here, we review our current understanding of the underlying mechanisms responsible for the development and maturation of these interdependent processes.
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Affiliation(s)
- William Goodyer
- Cardiovascular Institute, Stanford University, Stanford, CA 94305, USA,Division of Pediatric Cardiology, Department of Pediatrics, Lucille Packard Children’s Hospital, Stanford, CA 94305, USA
| | - Sean M. Wu
- Cardiovascular Institute, Stanford University, Stanford, CA 94305, USA,Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA,Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA,Correspondence: Sean M. Wu, M.D. PhD., Lokey Stem Cell Building, Room G1120A, 265 Campus Drive, Stanford, CA 94305, Phone No. 650-724-4498, Fax No. 650-726-4689,
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11
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Mohan RA, Boukens BJ, Christoffels VM. Developmental Origin of the Cardiac Conduction System: Insight from Lineage Tracing. Pediatr Cardiol 2018; 39:1107-1114. [PMID: 29774393 PMCID: PMC6096846 DOI: 10.1007/s00246-018-1906-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 05/08/2018] [Indexed: 12/17/2022]
Abstract
The components of the cardiac conduction system (CCS) generate and propagate the electrical impulse that initiates cardiac contraction. These interconnected components share properties, such as automaticity, that set them apart from the working myocardium of the atria and ventricles. A variety of tools and approaches have been used to define the CCS lineages. These include genetic labeling of cells expressing lineage markers and fate mapping of dye labeled cells, which we will discuss in this review. We conclude that there is not a single CCS lineage, but instead early cell fate decisions segregate the lineages of the CCS components while they remain interconnected. The latter is relevant for development of therapies for conduction system disease that focus on reprogramming cardiomyocytes or instruction of pluripotent stem cells.
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Affiliation(s)
- Rajiv A. Mohan
- Department of Medical Biology, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Bastiaan J. Boukens
- Department of Medical Biology, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
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12
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Cellular Physiology and Clinical Manifestations of Fascicular Arrhythmias in Normal Hearts. JACC Clin Electrophysiol 2017; 3:1343-1355. [PMID: 29759663 DOI: 10.1016/j.jacep.2017.07.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 06/22/2017] [Accepted: 07/27/2017] [Indexed: 11/22/2022]
Abstract
Fascicular ventricular arrhythmias represent a spectrum of ventricular tachycardias dependent on the specialized conduction system. Although they are more common in structurally abnormal hearts, there is an increasing body of literature describing their role in normal hearts. In this review, the authors present data from both basic and clinical research that explore the current understanding of idiopathic fascicular ventricular arrhythmias. Evaluation of the cellular electrophysiology of the Purkinje cells shows clear evidence of enhanced automaticity and triggered activity as potential mechanisms of arrhythmias. Perhaps more importantly, heterogeneity in conduction system velocity and refractoriness of the left ventricular conduction system in animal models are in line with clinical descriptions of re-entrant fascicular arrhythmias in humans. Further advances in our understanding of the conduction system will help bridge the current gap between basic science and clinical fascicular arrhythmias.
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13
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Reher TA, Wang Z, Hsueh CH, Chang PC, Pan Z, Kumar M, Patel J, Tan J, Shen C, Chen Z, Fishbein MC, Rubart M, Boyden P, Chen PS. Small-Conductance Calcium-Activated Potassium Current in Normal Rabbit Cardiac Purkinje Cells. J Am Heart Assoc 2017; 6:JAHA.117.005471. [PMID: 28550095 PMCID: PMC5669169 DOI: 10.1161/jaha.117.005471] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Background Purkinje cells (PCs) are important in cardiac arrhythmogenesis. Whether small‐conductance calcium‐activated potassium (SK) channels are present in PCs remains unclear. We tested the hypotheses that subtype 2 SK (SK2) channel proteins and apamin‐sensitive SK currents are abundantly present in PCs. Methods and Results We studied 25 normal rabbit ventricles, including 13 patch‐clamp studies, 4 for Western blotting, and 8 for immunohistochemical staining. Transmembrane action potentials were recorded in current‐clamp mode using the perforated‐patch technique. For PCs, the apamin (100 nmol/L) significantly prolonged action potential duration measured to 80% repolarization by an average of 10.4 ms (95% CI, 0.11–20.72) (n=9, P=0.047). Voltage‐clamp study showed that apamin‐sensitive SK current density was significantly larger in PCs compared with ventricular myocytes at potentials ≥0 mV. Western blotting of SK2 expression showed that the SK2 protein expression in the midmyocardium was 58% (P=0.028) and the epicardium was 50% (P=0.018) of that in the pseudotendons. Immunostaining of SK2 protein showed that PCs stained stronger than ventricular myocytes. Confocal microscope study showed SK2 protein was distributed to the periphery of the PCs. Conclusions SK2 proteins are more abundantly present in the PCs than in the ventricular myocytes of normal rabbit ventricles. Apamin‐sensitive SK current is important in ventricular repolarization of normal PCs.
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Affiliation(s)
- Thomas A Reher
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indianapolis, IN
| | - Zhuo Wang
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indianapolis, IN.,Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Chia-Hsiang Hsueh
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indianapolis, IN
| | - Po-Cheng Chang
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indianapolis, IN
| | - Zhenwei Pan
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indianapolis, IN
| | - Mohineesh Kumar
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indianapolis, IN
| | - Jheel Patel
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indianapolis, IN
| | - Jian Tan
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indianapolis, IN
| | - Changyu Shen
- Smith Center for Outcomes Research in Cardiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
| | - Zhenhui Chen
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indianapolis, IN
| | - Michael C Fishbein
- Department of Pathology and Laboratory Medicine, UCLA Medical Center, Los Angeles, CA
| | - Michael Rubart
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN
| | - Penelope Boyden
- Department of Pharmacology, Columbia University, New York, NY
| | - Peng-Sheng Chen
- The Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indianapolis, IN
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14
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Lineages of the Cardiac Conduction System. J Cardiovasc Dev Dis 2017; 4:jcdd4020005. [PMID: 29367537 PMCID: PMC5715704 DOI: 10.3390/jcdd4020005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 04/19/2017] [Accepted: 04/24/2017] [Indexed: 12/15/2022] Open
Abstract
The cardiac conduction system (CCS) initiates and coordinately propagates the electrical impulse to orchestrate the heartbeat. It consists of a set of interconnected components with shared properties. A better understanding of the origin and specification of CCS lineages has allowed us to better comprehend the etiology of CCS disease and has provided leads for development of therapies. A variety of technologies and approaches have been used to investigate CCS lineages, which will be summarized in this review. The findings imply that there is not a single CCS lineage. In contrast, early cell fate decisions segregate the lineages of the CCS components while they remain connected to each other.
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15
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Partial Reprogramming of Pluripotent Stem Cell-Derived Cardiomyocytes into Neurons. Sci Rep 2017; 7:44840. [PMID: 28327614 PMCID: PMC5361100 DOI: 10.1038/srep44840] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 02/14/2017] [Indexed: 01/17/2023] Open
Abstract
Direct reprogramming of somatic cells has been demonstrated, however, it is unknown whether electrophysiologically-active somatic cells derived from separate germ layers can be interconverted. We demonstrate that partial direct reprogramming of mesoderm-derived cardiomyocytes into neurons is feasible, generating cells exhibiting structural and electrophysiological properties of both cardiomyocytes and neurons. Human and mouse pluripotent stem cell-derived CMs (PSC-CMs) were transduced with the neurogenic transcription factors Brn2, Ascl1, Myt1l and NeuroD. We found that CMs adopted neuronal morphologies as early as day 3 post-transduction while still retaining a CM gene expression profile. At week 1 post-transduction, we found that reprogrammed CMs expressed neuronal markers such as Tuj1, Map2, and NCAM. At week 3 post-transduction, mature neuronal markers such as vGlut and synapsin were observed. With single-cell qPCR, we temporally examined CM gene expression and observed increased expression of neuronal markers Dcx, Map2, and Tubb3. Patch-clamp analysis confirmed the neuron-like electrophysiological profile of reprogrammed CMs. This study demonstrates that PSC-CMs are amenable to partial neuronal conversion, yielding a population of cells exhibiting features of both neurons and CMs.
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16
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Pasquier J, Gupta R, Rioult D, Hoarau-Véchot J, Courjaret R, Machaca K, Al Suwaidi J, Stanley EG, Rafii S, Elliott DA, Abi Khalil C, Rafii A. Coculturing with endothelial cells promotes in vitro maturation and electrical coupling of human embryonic stem cell-derived cardiomyocytes. J Heart Lung Transplant 2017; 36:684-693. [PMID: 28169114 DOI: 10.1016/j.healun.2017.01.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 12/22/2016] [Accepted: 01/04/2017] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Pluripotent human embryonic stem cells (hESC) are a promising source of repopulating cardiomyocytes. We hypothesized that we could improve maturation of cardiomyocytes and facilitate electrical interconnections by creating a model that more closely resembles heart tissue; that is, containing both endothelial cells (ECs) and cardiomyocytes. METHODS We induced cardiomyocyte differentiation in the coculture of an hESC line expressing the cardiac reporter NKX2.5-green fluorescent protein (GFP), and an Akt-activated EC line (E4+ECs). We quantified spontaneous beating rates, synchrony, and coordination between different cardiomyocyte clusters using confocal imaging of Fura Red-detected calcium transients and computer-assisted image analysis. RESULTS After 8 days in culture, 94% ± 6% of the NKX2-5GFP+ cells were beating when hESCs embryonic bodies were plated on E4+ECs compared with 34% ± 12.9% for controls consisting of hESCs cultured on BD Matrigel (BD Biosciences) without ECs at Day 11 in culture. The spatial organization of beating areas in cocultures was different. The GFP+ cardiomyocytes were close to the E4+ECs. The average beats/min of the cardiomyocytes in coculture was faster and closer to physiologic heart rates compared with controls (50 ± 14 [n = 13] vs 25 ± 9 [n = 8]; p < 0.05). The coculture with ECs led to synchronized beating relying on the endothelial network, as illustrated by the loss of synchronization upon the disruption of endothelial bridges. CONCLUSIONS The coculturing of differentiating cardiomyocytes with Akt-activated ECs but not EC-conditioned media results in (1) improved efficiency of the cardiomyocyte differentiation protocol and (2) increased maturity leading to better intercellular coupling with improved chronotropy and synchrony.
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Affiliation(s)
- Jennifer Pasquier
- Stem Cell and Microenvironment Laboratory, Weill Cornell Medicine-Qatar, Doha, Qatar; Department of Genetic Medicine, Weill Cornell Medicine, New York, New York, USA
| | - Renuka Gupta
- Stem Cell and Microenvironment Laboratory, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Damien Rioult
- UMR_I 02 INERIS-URCA-ULH Unité Stress Environnementaux et BIOsurveillance des milieux aquatiques, Université de Reims, Reims, France
| | - Jessica Hoarau-Véchot
- Stem Cell and Microenvironment Laboratory, Weill Cornell Medicine-Qatar, Doha, Qatar; Cardiovascular Epigenetics Laboratory, Department of Genetic Medicine, Doha, Qatar
| | - Raphael Courjaret
- Department of Physiology and Biophysics, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Khaled Machaca
- Department of Physiology and Biophysics, Weill Cornell Medicine-Qatar, Doha, Qatar
| | | | - Edouard G Stanley
- Department of Medicine, Weill Cornell Medicine, New York, New York; Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Shahin Rafii
- Department of Medicine, Weill Cornell Medicine, New York, New York
| | - David A Elliott
- Department of Medicine, Weill Cornell Medicine, New York, New York; Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Charbel Abi Khalil
- Department of Genetic Medicine, Weill Cornell Medicine, New York, New York, USA; Cardiovascular Epigenetics Laboratory, Department of Genetic Medicine, Doha, Qatar; Heart Hospital, Hamad Medical Corporation, Doha, Qatar; Department of Medicine, Weill Cornell Medicine, New York, New York, USA.
| | - Arash Rafii
- Stem Cell and Microenvironment Laboratory, Weill Cornell Medicine-Qatar, Doha, Qatar; Department of Genetic Medicine, Weill Cornell Medicine, New York, New York, USA.
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17
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Transmural electrophysiological heterogeneity, the T-wave and ventricular arrhythmias. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:202-214. [DOI: 10.1016/j.pbiomolbio.2016.05.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/21/2016] [Accepted: 05/03/2016] [Indexed: 01/05/2023]
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18
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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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Affiliation(s)
- Damelys Calderon
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, NY, USA.,Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, NY, USA.,Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, NY, USA
| | - Evan Bardot
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, NY, USA.,Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, NY, USA.,Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, NY, USA
| | - Nicole Dubois
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, NY, USA.,Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, NY, USA.,Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, NY, USA
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19
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van Weerd JH, Christoffels VM. The formation and function of the cardiac conduction system. Development 2016; 143:197-210. [PMID: 26786210 DOI: 10.1242/dev.124883] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The cardiac conduction system (CCS) consists of distinctive components that initiate and conduct the electrical impulse required for the coordinated contraction of the cardiac chambers. CCS development involves complex regulatory networks that act in stage-, tissue- and dose-dependent manners, and recent findings indicate that the activity of these networks is sensitive to common genetic variants associated with cardiac arrhythmias. Here, we review how these findings have provided novel insights into the regulatory mechanisms and transcriptional networks underlying CCS formation and function.
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Affiliation(s)
- Jan Hendrik van Weerd
- Department of Anatomy, Embryology & Physiology, Academic Medical Center, Amsterdam 1105 AZ, The Netherlands
| | - Vincent M Christoffels
- Department of Anatomy, Embryology & Physiology, Academic Medical Center, Amsterdam 1105 AZ, The Netherlands
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20
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McCormick ME, Tzima E. Pulling on my heartstrings: mechanotransduction in cardiac development and function. Curr Opin Hematol 2016; 23:235-42. [PMID: 26906028 PMCID: PMC4823169 DOI: 10.1097/moh.0000000000000240] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
PURPOSE OF REVIEW Endothelial cells line the surface of the cardiovascular system and display a large degree of heterogeneity due to developmental origin and location. Despite this heterogeneity, all endothelial cells are exposed to wall shear stress (WSS) imparted by the frictional force of flowing blood, which plays an important role in determining the endothelial cell phenotype. Although the effects of WSS have been greatly studied in vascular endothelial cells, less is known about the role of WSS in regulating cardiac function and cardiac endothelial cells. RECENT FINDINGS Recent advances in genetic and imaging technologies have enabled a more thorough investigation of cardiac hemodynamics. Using developmental models, shear stress sensing by endocardial endothelial cells has been shown to play an integral role in proper cardiac development including morphogenesis and formation of the conduction system. In the adult, less is known about hemodynamics and endocardial endothelial cells, but a clear role for WSS in the development of coronary and valvular disease is increasingly appreciated. SUMMARY Future research will further elucidate a role for WSS in the developing and adult heart, and understanding this dynamic relationship may represent a potential therapeutic target for the treatment of cardiomyopathies.
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Affiliation(s)
- Margaret E. McCormick
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ellie Tzima
- Division of Cardiovascular Medicine,Wellcome Trust Centre for Human Genetics, Oxford University, Oxford, UK
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21
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The "Dead-End Tract" and Its Role in Arrhythmogenesis. J Cardiovasc Dev Dis 2016; 3:jcdd3020011. [PMID: 29367562 PMCID: PMC5715688 DOI: 10.3390/jcdd3020011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 02/02/2016] [Accepted: 03/17/2016] [Indexed: 11/17/2022] Open
Abstract
Idiopathic outflow tract ventricular arrhythmias (VAs) represent a significant proportion of all VAs. The mechanism is thought to be catecholamine-mediated delayed after depolarizations and triggered activity, although other etiologies should be considered. In the adult cardiac conduction system it has been demonstrated that sometimes an embryonic branch, the so-called "dead-end tract", persists beyond the bifurcation of the right and left bundle branch (LBB). Several findings suggest an involvement of this tract in idiopathic VAs (IVAs). The aim of this review is to summarize our current knowledge and the possible clinical significance of this tract.
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22
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Watanabe M, Rollins AM, Polo-Parada L, Ma P, Gu S, Jenkins MW. Probing the Electrophysiology of the Developing Heart. J Cardiovasc Dev Dis 2016; 3:jcdd3010010. [PMID: 29367561 PMCID: PMC5715694 DOI: 10.3390/jcdd3010010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/08/2016] [Accepted: 03/10/2016] [Indexed: 12/14/2022] Open
Abstract
Many diseases that result in dysfunction and dysmorphology of the heart originate in the embryo. However, the embryonic heart presents a challenging subject for study: especially challenging is its electrophysiology. Electrophysiological maturation of the embryonic heart without disturbing its physiological function requires the creation and deployment of novel technologies along with the use of classical techniques on a range of animal models. Each tool has its strengths and limitations and has contributed to making key discoveries to expand our understanding of cardiac development. Further progress in understanding the mechanisms that regulate the normal and abnormal development of the electrophysiology of the heart requires integration of this functional information with the more extensively elucidated structural and molecular changes.
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Affiliation(s)
- Michiko Watanabe
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
- Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Andrew M Rollins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Luis Polo-Parada
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65201, USA.
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65201, USA.
| | - Pei Ma
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Shi Gu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Michael W Jenkins
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
- Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, OH 44106, USA.
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23
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Kelder TP, Vicente-Steijn R, Poelmann RE, Mummery CL, DeRuiter MC, Jongbloed MRM. The avian embryo to study development of the cardiac conduction system. Differentiation 2016; 91:90-103. [PMID: 26856662 DOI: 10.1016/j.diff.2016.01.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 01/26/2016] [Indexed: 11/17/2022]
Abstract
The avian embryo has long been a popular model system in developmental biology. The easy accessibility of the embryo makes it particularly suitable for in ovo microsurgery and manipulation. Re-incubation of the embryo allows long-term follow-up of these procedures. The current review focuses on the variety of techniques available to study development of the cardiac conduction system in avian embryos. Based on the large amount of relevant data arising from experiments in avian embryos, we conclude that the avian embryo has and will continue to be a powerful model system to study development in general and the developing cardiac conduction system in particular.
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Affiliation(s)
- Tim P Kelder
- Anatomy & Embryology, Leiden University Medical Center, The Netherlands
| | - Rebecca Vicente-Steijn
- Anatomy & Embryology, Leiden University Medical Center, The Netherlands; Cardiology, Leiden University Medical Center, The Netherlands; ICIN Netherlands Heart Institute, Utrecht, The Netherlands
| | - Robert E Poelmann
- Cardiology, Leiden University Medical Center, The Netherlands; Integrative Zoology, Institute Biology, University Leiden, The Netherlands
| | | | - Marco C DeRuiter
- Anatomy & Embryology, Leiden University Medical Center, The Netherlands
| | - Monique R M Jongbloed
- Anatomy & Embryology, Leiden University Medical Center, The Netherlands; Cardiology, Leiden University Medical Center, The Netherlands.
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24
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Autonomous beating rate adaptation in human stem cell-derived cardiomyocytes. Nat Commun 2016; 7:10312. [PMID: 26785135 PMCID: PMC4735644 DOI: 10.1038/ncomms10312] [Citation(s) in RCA: 127] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Accepted: 11/27/2015] [Indexed: 02/06/2023] Open
Abstract
The therapeutic success of human stem cell-derived cardiomyocytes critically depends on their ability to respond to and integrate with the surrounding electromechanical environment. Currently, the immaturity of human cardiomyocytes derived from stem cells limits their utility for regenerative medicine and biological research. We hypothesize that biomimetic electrical signals regulate the intrinsic beating properties of cardiomyocytes. Here we show that electrical conditioning of human stem cell-derived cardiomyocytes in three-dimensional culture promotes cardiomyocyte maturation, alters their automaticity and enhances connexin expression. Cardiomyocytes adapt their autonomous beating rate to the frequency at which they were stimulated, an effect mediated by the emergence of a rapidly depolarizing cell population, and the expression of hERG. This rate-adaptive behaviour is long lasting and transferable to the surrounding cardiomyocytes. Thus, electrical conditioning may be used to promote cardiomyocyte maturation and establish their automaticity, with implications for cell-based reduction of arrhythmia during heart regeneration.
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25
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Lagerqvist E, Finnin B, Elliott D, Anderson D, Wu S, Pouton C, Haynes J. Comparing mouse and human pluripotent stem cell derived cardiac cells: Both systems have advantages for pharmacological and toxicological screening. J Pharmacol Toxicol Methods 2015; 74:17-25. [DOI: 10.1016/j.vascn.2015.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 04/21/2015] [Accepted: 04/29/2015] [Indexed: 12/13/2022]
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26
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Tsai SY, Maass K, Lu J, Fishman GI, Chen S, Evans T. Efficient Generation of Cardiac Purkinje Cells from ESCs by Activating cAMP Signaling. Stem Cell Reports 2015; 4:1089-102. [PMID: 26028533 PMCID: PMC4471825 DOI: 10.1016/j.stemcr.2015.04.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 04/27/2015] [Accepted: 04/30/2015] [Indexed: 12/13/2022] Open
Abstract
Dysfunction of the specialized cardiac conduction system (CCS) is associated with life-threatening arrhythmias. Strategies to derive CCS cells, including rare Purkinje cells (PCs), would facilitate models for mechanistic studies and drug discovery and also provide new cellular materials for regenerative therapies. A high-throughput chemical screen using CCS:lacz and Contactin2:egfp (Cntn2:egfp) reporter embryonic stem cell (ESC) lines was used to discover a small molecule, sodium nitroprusside (SN), that efficiently promotes the generation of cardiac cells that express gene profiles and generate action potentials of PC-like cells. Imaging and mechanistic studies suggest that SN promotes the generation of PCs from cardiac progenitors initially expressing cardiac myosin heavy chain and that it does so by activating cyclic AMP signaling. These findings provide a strategy to derive scalable PCs, along with insight into the ontogeny of CCS development. A chemical screen was carried out for compounds that induce cardiac conduction cells Two ESC reporter lines were used to identify lead hits Sodium nitroprusside efficiently generated scalable amounts of PC-like cells By activating cAMP signaling, PCs are derived from cardiac progenitors
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Affiliation(s)
- Su-Yi Tsai
- Department of Surgery, Weill Cornell Medical College, New York, NY 10065, USA
| | - Karen Maass
- Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, NY 10016, USA
| | - Jia Lu
- Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, NY 10016, USA
| | - Glenn I Fishman
- Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, NY 10016, USA.
| | - Shuibing Chen
- Department of Surgery, Weill Cornell Medical College, New York, NY 10065, USA.
| | - Todd Evans
- Department of Surgery, Weill Cornell Medical College, New York, NY 10065, USA.
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27
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Hemodynamic forces regulate developmental patterning of atrial conduction. PLoS One 2014; 9:e115207. [PMID: 25503944 PMCID: PMC4264946 DOI: 10.1371/journal.pone.0115207] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Accepted: 11/19/2014] [Indexed: 02/01/2023] Open
Abstract
Anomalous action potential conduction through the atrial chambers of the heart can lead to severe cardiac arrhythmia. To date, however, little is known regarding the mechanisms that pattern proper atrial conduction during development. Here we demonstrate that atrial muscle functionally diversifies into at least two heterogeneous subtypes, thin-walled myocardium and rapidly conducting muscle bundles, during a developmental window just following cardiac looping. During this process, atrial muscle bundles become enriched for the fast conduction markers Cx40 and Nav1.5, similar to the precursors of the fast conduction Purkinje fiber network located within the trabeculae of the ventricles. In contrast to the ventricular trabeculae, however, atrial muscle bundles display an increased proliferation rate when compared to the surrounding myocardium. Interestingly, mechanical loading of the embryonic atrial muscle resulted in an induction of Cx40, Nav1.5 and the cell cycle marker Cyclin D1, while decreasing atrial pressure via in vivo ligation of the vitelline blood vessels results in decreased atrial conduction velocity. Taken together, these data establish a novel model for atrial conduction patterning, whereby hemodynamic stretch coordinately induces proliferation and fast conduction marker expression, which in turn promotes the formation of large diameter muscle bundles to serve as preferential routes of conduction.
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Hua LL, Vedantham V, Barnes RM, Hu J, Robinson AS, Bressan M, Srivastava D, Black BL. Specification of the mouse cardiac conduction system in the absence of Endothelin signaling. Dev Biol 2014; 393:245-254. [PMID: 25050930 PMCID: PMC4143461 DOI: 10.1016/j.ydbio.2014.07.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 07/04/2014] [Accepted: 07/11/2014] [Indexed: 10/25/2022]
Abstract
Coordinated contraction of the heart is essential for survival and is regulated by the cardiac conduction system. Contraction of ventricular myocytes is controlled by the terminal part of the conduction system known as the Purkinje fiber network. Lineage analyses in chickens and mice have established that the Purkinje fibers of the peripheral ventricular conduction system arise from working myocytes during cardiac development. It has been proposed, based primarily on gain-of-function studies, that Endothelin signaling is responsible for myocyte-to-Purkinje fiber transdifferentiation during avian heart development. However, the role of Endothelin signaling in mammalian conduction system development is less clear, and the development of the cardiac conduction system in mice lacking Endothelin signaling has not been previously addressed. Here, we assessed the specification of the cardiac conduction system in mouse embryos lacking all Endothelin signaling. We found that mouse embryos that were homozygous null for both ednra and ednrb, the genes encoding the two Endothelin receptors in mice, were born at predicted Mendelian frequency and had normal specification of the cardiac conduction system and apparently normal electrocardiograms with normal QRS intervals. In addition, we found that ednra expression within the heart was restricted to the myocardium while ednrb expression in the heart was restricted to the endocardium and coronary endothelium. By establishing that ednra and ednrb are expressed in distinct compartments within the developing mammalian heart and that Endothelin signaling is dispensable for specification and function of the cardiac conduction system, this work has important implications for our understanding of mammalian cardiac development.
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Affiliation(s)
- Lisa L Hua
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158-2517, USA
| | - Vasanth Vedantham
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158-2517, USA; Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, CA 94158-2517, USA; Department of Medicine, University of California, San Francisco, CA 94158-2517, USA
| | - Ralston M Barnes
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158-2517, USA
| | - Jianxin Hu
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158-2517, USA
| | - Ashley S Robinson
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158-2517, USA
| | - Michael Bressan
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158-2517, USA
| | - Deepak Srivastava
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158-2517, USA; Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, CA 94158-2517, USA; Department of Pediatrics, University of California, San Francisco, CA 94158-2517, USA
| | - Brian L Black
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158-2517, USA; Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158-2517, USA.
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Hartman ME, Liu Y, Zhu WZ, Chien WM, Weldy CS, Fishman GI, Laflamme MA, Chin MT. Myocardial deletion of transcription factor CHF1/Hey2 results in altered myocyte action potential and mild conduction system expansion but does not alter conduction system function or promote spontaneous arrhythmias. FASEB J 2014; 28:3007-15. [PMID: 24687990 DOI: 10.1096/fj.14-251728] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
CHF1/Hey2 is a Notch-responsive basic helix-loop-helix transcription factor involved in cardiac development. Common variants in Hey2 are associated with Brugada syndrome. We hypothesized that absence of CHF1/Hey2 would result in abnormal cellular electrical activity, altered cardiac conduction system (CCS) development, and increased arrhythmogenesis. We isolated neonatal CHF/Hey2-knockout (KO) cardiac myocytes and measured action potentials and ion channel subunit gene expression. We also crossed myocardial-specific CHF1/Hey2-KO mice with cardiac conduction system LacZ reporter mice and stained for conduction system tissue. We also performed ambulatory ECG monitoring for arrhythmias and heart rate variability. Neonatal cardiomyocytes from CHF1/Hey2-KO mice demonstrate a 50% reduction in action potential dV/dT, a 50-75% reduction in SCN5A, KCNJ2, and CACNA1C ion channel subunit gene expression, and an increase in delayed afterdepolarizations from 0/min to 12/min. CHF1/Hey2 cKO CCS-lacZ mice have a ∼3-fold increase in amount of CCS tissue. Ambulatory ECG monitoring showed no difference in cardiac conduction, arrhythmias, or heart rate variability. Wild-type cells or animals were used in all experiments. CHF1/Hey2 may contribute to Brugada syndrome by influencing the expression of SCN5A and formation of the cardiac conduction system, but its absence does not cause baseline conduction defects or arrhythmias in the adult mouse.-Hartman, M. E., Liu, Y., Zhu, W.-Z., Chien, W.-M., Weldy, C. S., Fishman, G. I., Laflamme, M. A., Chin, M. T. Myocardial deletion of transcription factor CHF1/Hey2 results in altered myocyte action potential and mild conduction system expansion but does not alter conduction system function or promote spontaneous arrhythmias.
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Affiliation(s)
| | - Yonggang Liu
- Division of Cardiology, Department of Medicine, and
| | - Wei-Zhong Zhu
- Department of Pathology, Institute for Stem Cells and Regenerative Medicine, University of Washington, Seattle, Washington, USA; and
| | | | - Chad S Weldy
- Division of Cardiology, Department of Medicine, and
| | - Glenn I Fishman
- The Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, New York, USA
| | - Michael A Laflamme
- Department of Pathology, Institute for Stem Cells and Regenerative Medicine, University of Washington, Seattle, Washington, USA; and
| | - Michael T Chin
- Division of Cardiology, Department of Medicine, and Department of Pathology, Institute for Stem Cells and Regenerative Medicine, University of Washington, Seattle, Washington, USA; and
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Lewandowski SL, Janardhan HP, Smee KM, Bachman M, Sun Z, Lazar MA, Trivedi CM. Histone deacetylase 3 modulates Tbx5 activity to regulate early cardiogenesis. Hum Mol Genet 2014; 23:3801-9. [PMID: 24565863 DOI: 10.1093/hmg/ddu093] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Congenital heart defects often result from improper differentiation of cardiac progenitor cells. Although transcription factors involved in cardiac progenitor cell differentiation have been described, the associated chromatin modifiers in this process remain largely unknown. Here we show that mouse embryos lacking the chromatin-modifying enzyme histone deacetylase 3 (Hdac3) in cardiac progenitor cells exhibit precocious cardiomyocyte differentiation, severe cardiac developmental defects, upregulation of Tbx5 target genes and embryonic lethality. Hdac3 physically interacts with Tbx5 and modulates its acetylation to repress Tbx5-dependent activation of cardiomyocyte lineage-specific genes. These findings reveal that Hdac3 plays a critical role in cardiac progenitor cells to regulate early cardiogenesis.
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Affiliation(s)
- Sara L Lewandowski
- Cardiovascular Medicine and Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Harish P Janardhan
- Cardiovascular Medicine and Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Kevin M Smee
- Cardiovascular Medicine and Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | | | - Zheng Sun
- Division of Endocrinology, Diabetes, Metabolism, Department of Medicine and The Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mitchell A Lazar
- Division of Endocrinology, Diabetes, Metabolism, Department of Medicine and The Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Chinmay M Trivedi
- Cardiovascular Medicine and Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA,
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Wu M, Peng S, Zhao Y. Inducible gene deletion in the entire cardiac conduction system using Hcn4-CreERT2 BAC transgenic mice. Genesis 2013; 52:134-40. [PMID: 24281837 DOI: 10.1002/dvg.22730] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 11/21/2013] [Accepted: 11/21/2013] [Indexed: 11/11/2022]
Abstract
Developmental defects and disruption of molecular pathways of the cardiac conduction system (CCS) can cause life-threatening cardiac arrhythmias. Despite decades of effort, knowledge about the development and molecular control of the CCS remains primitive. Mouse genetics, complementary to other approaches such as human genetics, has become a key tool for exploring the developmental processes of various organs and associated diseases. Genetic analysis using mouse models will likely provide great insights about the development of the CCS, which can facilitate the development of novel therapeutic strategies to treat arrhythmias. To enable genetic studies of the CCS, CCS-associated Cre mouse models are essential. However, existing mouse models with Cre activity reported in the CCS have various limitations such as Cre leak, haploinsufficiency, and inadequate specificity of the Cre activity. To circumvent those limitations, we successfully generated Hcn4-CreERT2 bacterial artificial chromosome (BAC) transgenic mice using BAC recombineering in which Cre activity was specifically detected in the entire CCS after tamoxifen induction. Our Hcn4-CreERT2 BAC transgenic line will be an invaluable genetic tool with which to dissect the developmental control of CCS and arrhythmias.
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Affiliation(s)
- Meng Wu
- Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
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Liang X, Wang G, Lin L, Lowe J, Zhang Q, Bu L, Chen Y, Chen J, Sun Y, Evans SM. HCN4 dynamically marks the first heart field and conduction system precursors. Circ Res 2013; 113:399-407. [PMID: 23743334 DOI: 10.1161/circresaha.113.301588] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
RATIONALE To date, there has been no specific marker of the first heart field to facilitate understanding of contributions of the first heart field to cardiac lineages. Cardiac arrhythmia is a leading cause of death, often resulting from abnormalities in the cardiac conduction system (CCS). Understanding origins and identifying markers of CCS lineages are essential steps toward modeling diseases of the CCS and for development of biological pacemakers. OBJECTIVE To investigate HCN4 as a marker for the first heart field and for precursors of distinct components of the CCS, and to gain insight into contributions of first and second heart lineages to the CCS. METHODS AND RESULTS HCN4CreERT2, -nuclear LacZ, and -H2BGFP mouse lines were generated. HCN4 expression was examined by means of immunostaining with HCN4 antibody and reporter gene expression. Lineage studies were performed using HCN4CreERT2, Isl1Cre, Nkx2.5Cre, and Tbx18Cre, coupled to coimmunostaining with CCS markers. Results demonstrated that, at cardiac crescent stages, HCN4 marks the first heart field, with HCN4CreERT2 allowing assessment of cell fates adopted by first heart field myocytes. Throughout embryonic development, HCN4 expression marked distinct CCS precursors at distinct stages, marking the entire CCS by late fetal stages. We also noted expression of HCN4 in distinct subsets of endothelium at specific developmental stages. CONCLUSIONS This study provides insight into contributions of first and second heart lineages to the CCS and highlights the potential use of HCN4 in conjunction with other markers for optimization of protocols for generation and isolation of specific conduction system precursors.
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Affiliation(s)
- Xingqun Liang
- Skaggs School of Pharmacy and Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA.,Key Laboratory of Arrhythmia, Ministry of Education, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Gang Wang
- Skaggs School of Pharmacy and Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
| | - Lizhu Lin
- Skaggs School of Pharmacy and Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
| | - Jennifer Lowe
- Skaggs School of Pharmacy and Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
| | - Qingquang Zhang
- Key Laboratory of Arrhythmia, Ministry of Education, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Lei Bu
- Skaggs School of Pharmacy and Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
| | - Yihan Chen
- Key Laboratory of Arrhythmia, Ministry of Education, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Ju Chen
- Skaggs School of Pharmacy and Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
| | - Yunfu Sun
- Skaggs School of Pharmacy and Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA.,Key Laboratory of Arrhythmia, Ministry of Education, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Sylvia M Evans
- Skaggs School of Pharmacy and Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
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Miquerol L, Bellon A, Moreno N, Beyer S, Meilhac SM, Buckingham M, Franco D, Kelly RG. Resolving cell lineage contributions to the ventricular conduction system with a Cx40-GFP allele: a dual contribution of the first and second heart fields. Dev Dyn 2013; 242:665-77. [PMID: 23526457 DOI: 10.1002/dvdy.23964] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Revised: 03/08/2013] [Accepted: 03/11/2013] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The ventricular conduction system (VCS) coordinates the heartbeat and is composed of central components (the atrioventricular node, bundle, and right and left bundle branches) and a peripheral Purkinje fiber network. Conductive myocytes develop from common progenitor cells with working myocytes in a bimodal process of lineage restriction followed by limited outgrowth. The lineage relationship between progenitor cells giving rise to different components of the VCS is unclear. RESULTS Cell lineage contributions to different components of the VCS were analysed by a combination of retrospective clonal analysis, regionalized transgene expression studies, and genetic tracing experiments using Connexin40-GFP mice that precisely delineate the VCS. Analysis of a library of hearts containing rare large clusters of clonally related myocytes identifies two VCS lineages encompassing either the right Purkinje fiber network or left bundle branch. Both lineages contribute to the atrioventricular bundle and right bundle branch that segregate early from working myocytes. Right and left VCS lineages share the transcriptional program of the respective ventricular working myocytes and genetic tracing experiments discount alternate progenitor cell contributions to the VCS. CONCLUSIONS The mammalian VCS is comprised of cells derived from two lineages, supporting a dual contribution of first and second heart field progenitor cells.
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Affiliation(s)
- Lucile Miquerol
- Aix-Marseille University, CNRS UMR 7288, Developmental Biology Institute of Marseille, Marseille, France.
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Abstract
The cardiac conduction system is a specialized tract of myocardial cells responsible for maintaining normal cardiac rhythm. Given its critical role in coordinating cardiac performance, a detailed analysis of the molecular mechanisms underlying conduction system formation should inform our understanding of arrhythmia pathophysiology and affect the development of novel therapeutic strategies. Historically, the ability to distinguish cells of the conduction system from neighboring working myocytes presented a major technical challenge for performing comprehensive mechanistic studies. Early lineage tracing experiments suggested that conduction cells derive from cardiomyocyte precursors, and these claims have been substantiated by using more contemporary approaches. However, regional specialization of conduction cells adds an additional layer of complexity to this system, and it appears that different components of the conduction system utilize unique modes of developmental formation. The identification of numerous transcription factors and their downstream target genes involved in regional differentiation of the conduction system has provided insight into how lineage commitment is achieved. Furthermore, by adopting cutting-edge genetic techniques in combination with sophisticated phenotyping capabilities, investigators have made substantial progress in delineating the regulatory networks that orchestrate conduction system formation and their role in cardiac rhythm and physiology. This review describes the connectivity of these gene regulatory networks in cardiac conduction system development and discusses how they provide a foundation for understanding normal and pathological human cardiac rhythms.
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Affiliation(s)
- Nikhil V Munshi
- Department of Internal Medicine, Cardiology Division, University of Texas Southwestern Medical Center, Dallas, TX 75390-8573, USA.
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Rentschler S, Yen AH, Lu J, Petrenko NB, Lu MM, Manderfield LJ, Patel VV, Fishman GI, Epstein JA. Myocardial Notch signaling reprograms cardiomyocytes to a conduction-like phenotype. Circulation 2012; 126:1058-66. [PMID: 22837163 DOI: 10.1161/circulationaha.112.103390] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Notch signaling has previously been shown to play an essential role in regulating cell fate decisions and differentiation during cardiogenesis in many systems including Drosophila, Xenopus, and mammals. We hypothesized that Notch may also be involved in directing the progressive lineage restriction of cardiomyocytes into specialized conduction cells. METHODS AND RESULTS In hearts where Notch signaling is activated within the myocardium from early development onward, Notch promotes a conduction-like phenotype based on ectopic expression of conduction system-specific genes and cell autonomous changes in electrophysiology. With the use of an in vitro assay to activate Notch in newborn cardiomyocytes, we observed global changes in the transcriptome, and in action potential characteristics, consistent with reprogramming to a conduction-like phenotype. CONCLUSIONS Notch can instruct the differentiation of chamber cardiac progenitors into specialized conduction-like cells. Plasticity remains in late-stage cardiomyocytes, which has potential implications for engineering of specialized cardiovascular tissues.
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Affiliation(s)
- Stacey Rentschler
- Cardiovascular Institute, University of Pennsylvania, 421 Curie Blvd, Philadelphia, PA 19104, USA.
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Normal and abnormal development of the cardiac conduction system; implications for conduction and rhythm disorders in the child and adult. Differentiation 2012; 84:131-48. [DOI: 10.1016/j.diff.2012.04.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Accepted: 04/16/2012] [Indexed: 11/20/2022]
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Zhang X, Guo JP, Chi YL, Liu YC, Zhang CS, Yang XQ, Lin HY, Jiang EP, Xiong SH, Zhang ZY, Liu BH. Endothelin-induced differentiation of Nkx2.5⁺ cardiac progenitor cells into pacemaking cells. Mol Cell Biochem 2012; 366:309-18. [PMID: 22527936 DOI: 10.1007/s11010-012-1309-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2011] [Accepted: 04/03/2012] [Indexed: 10/28/2022]
Abstract
The mechanisms governing the development of cardiac pacemaking and conduction system are not well understood. In order to provide evidence for the derivation of pacemaking cells and the signal that induce and maintain the cells in the developing heart, Nkx2.5(+) cardiac progenitor cells (CPCs) were isolated from embryonic heart tubes of rats. Endothelin-1 was subsequently added to the CPCs to induce differentiation of them towards cardiac pacemaking cells. After the treatment, Nkx2.5(+) CPCs displayed spontaneous beating and spontaneously electrical activity as what we have previously described. Furthermore, RT-PCR and immunofluorescence staining demonstrated that Tbx3 expression was increased and Nkx2.5 expression was decreased in the induced cells 4 days after ET-1 treatment. And the significantly increased expression of Hcn4 and connexin-45 were detected in the induced cells 10 days after the treatment. In addition, Nkx2.5(+) CPCs were transfected with pGCsi-Tbx3 4 days after ET-1 treatment in an attempt to determine the transcription regulatory factor governing the differentiation of the cells into cardiac pacemaking cells. The results showed that silencing of Tbx3 decreased the pacemaking activity and led to down-regulation of pacemaker genes in the induced cells. These results confirmed that Nkx2.5(+) CPCs differentiated into cardiac pacemaking cells after being treated with ET-1 and suggested that an ET-1-Tbx3 molecular pathway govern/mediate this process. In conclusion, our study support the notion that pacemaking cells originate from Nkx2.5(+) CPCs present in embryonic heart tubes and endothelin-1 might be involved in diversification of cardiomyogenic progenitors toward the cells.
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Affiliation(s)
- Xi Zhang
- Institute of Biomedical Engineering, The Second Military Medical University, Shanghai, China
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Mezzano V, Sheikh F. Cell-cell junction remodeling in the heart: possible role in cardiac conduction system function and arrhythmias? Life Sci 2011; 90:313-21. [PMID: 22227473 DOI: 10.1016/j.lfs.2011.12.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 12/13/2011] [Accepted: 12/15/2011] [Indexed: 11/28/2022]
Abstract
Anchoring cell-cell junctions (desmosomes, fascia adherens) play crucial roles in maintaining mechanical integrity of cardiac muscle cells and tissue. Genetic mutations and/or loss of critical components in these macromolecular structures are increasingly being associated with arrhythmogenic cardiomyopathies; however, their specific roles have been primarily attributed to effects within the working (ventricular) cardiac muscle. Growing evidence also points to a key role for anchoring cell-cell junction components in cardiac muscle cells of the cardiac conduction system. This is not only evidenced by the molecular and ultra-structural presence of anchoring cell junctions in specific compartments/structures of the cardiac conduction system (sinoatrial node, atrioventricular node, His-Purkinje system), but also because conduction system-related arrhythmias can be found in humans and mouse models of cardiomyopathies harboring defects and/or mutations in key anchoring cell-cell junction proteins. These studies emphasize the clinical need to understand the molecular and cellular role(s) for anchoring cell-cell junctions in cardiac conduction system function and arrhythmias. This review will focus on (i) experimental findings that underline an important role for anchoring cell-cell junctions in the cardiac conduction system, (ii) insights regarding involvement of these structures in age-related cardiac remodeling of the conduction system, (iii) summarizing available genetic mouse models that can target cardiac conduction system structures and (iv) implications of these findings on future therapies for arrhythmogenic heart diseases.
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Affiliation(s)
- Valeria Mezzano
- Department of Medicine (Cardiology Division), University of California-San Diego, La Jolla, CA 92093, USA
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Abstract
Regulation of organ growth is critical during embryogenesis. At the cellular level, mechanisms controlling the size of individual embryonic organs include cell proliferation, differentiation, migration, and attrition through cell death. All these mechanisms play a role in cardiac morphogenesis, but experimental studies have shown that the major determinant of cardiac size during prenatal development is myocyte proliferation. As this proliferative capacity becomes severely restricted after birth, the number of cell divisions that occur during embryogenesis limits the growth potential of the postnatal heart. We summarize here current knowledge concerning regional control of myocyte proliferation as related to cardiac morphogenesis and dysmorphogenesis. There are significant spatial and temporal differences in rates of cell division, peaking during the preseptation period and then gradually decreasing toward birth. Analysis of regional rates of proliferation helps to explain the mechanics of ventricular septation, chamber morphogenesis, and the development of the cardiac conduction system. Proliferation rates are influenced by hemodynamic loading, and transduced by autocrine and paracrine signaling by means of growth factors. Understanding the biological response of the developing heart to such factors and physical forces will further our progress in engineering artificial myocardial tissues for heart repair and designing optimal treatment strategies for congenital heart disease.
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Affiliation(s)
- David Sedmera
- Charles University in Prague, First Faculty of Medicine, Institute of Anatomy, Prague, Czech Republic.
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40
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Aanhaanen WTJ, Moorman AFM, Christoffels VM. Origin and development of the atrioventricular myocardial lineage: insight into the development of accessory pathways. ACTA ACUST UNITED AC 2011; 91:565-77. [PMID: 21630423 DOI: 10.1002/bdra.20826] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 03/11/2011] [Accepted: 03/14/2011] [Indexed: 12/16/2022]
Abstract
Defects originating from the atrioventricular canal region are part of a wide spectrum of congenital cardiovascular malformations that frequently affect newborns. These defects include partial or complete atrioventricular septal defects, atrioventricular valve defects, and arrhythmias, such as atrioventricular re-entry tachycardia, atrioventricular nodal block, and ventricular preexcitation. Insight into the cellular origin of the atrioventricular canal myocardium and the molecular mechanisms that control its development will aid in the understanding of the etiology of the atrioventricular defects. This review discusses current knowledge concerning the origin and fate of the atrioventricular canal myocardium, the molecular mechanisms that determine its specification and differentiation, and its role in the development of certain malformations such as those that underlie ventricular preexcitation.
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Affiliation(s)
- Wim T J Aanhaanen
- Heart Failure Research Center, Academic Medical Center, Meibergdreef 15, Amsterdam, The Netherlands
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Espinoza-Lewis RA, Liu H, Sun C, Chen C, Jiao K, Chen Y. Ectopic expression of Nkx2.5 suppresses the formation of the sinoatrial node in mice. Dev Biol 2011; 356:359-69. [PMID: 21640717 DOI: 10.1016/j.ydbio.2011.05.663] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Revised: 04/18/2011] [Accepted: 05/18/2011] [Indexed: 10/18/2022]
Abstract
The sinoatrial node (SAN), functionally known as the pacemaker, regulates the cardiac rhythm or heartbeat. Several genes are expressed in the developing SAN and form a genetic network regulating the fate of the SAN cells. The short stature homeobox gene Shox2 is an important player in the SAN genetic network by regulating the expression of different cardiac conduction molecular markers including the early cardiac differentiation marker Nkx2.5. Here we report that the expression patterns of Shox2 and Nkx2.5 are mutually exclusive from the earliest stages of the venous pole and the SAN formation. We show that tissue specific ectopic expression of Shox2 in the developing mouse heart downregulates the expression of Nkx2.5 and causes cardiac malformations; however, it is not sufficient to induce a SAN cell fate switch in the working myocardium. On the other hand, tissue specific overexpression of Nkx2.5 in the heart leads to severe hypoplasia of the SAN and the venous valves, dis-regulation of the SAN genetic network, and change of the SAN cell fate into working myocardium, and causes embryonic lethality, recapitulating the phenotypes including bradycardia observed in Shox2(-/-) mutants. These results indicate that Nkx2.5 activity is detrimental to the normal formation of the SAN. Taken together, our results demonstrate that Shox2 downregulation of Nkx2.5 is essential for the proper development of the SAN and that Shox2 functions to shield the SAN from becoming working myocardium by acting upstream of Nkx2.5.
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42
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Affiliation(s)
- David S Park
- Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, NY 10016, USA
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Miquerol L, Beyer S, Kelly RG. Establishment of the mouse ventricular conduction system. Cardiovasc Res 2011; 91:232-42. [DOI: 10.1093/cvr/cvr069] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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44
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Abstract
The myocardium of the heart is composed of multiple highly specialized myocardial lineages, including those of the ventricular and atrial myocardium, and the specialized conduction system. Specification and maturation of each of these lineages during heart development is a highly ordered, ongoing process involving multiple signaling pathways and their intersection with transcriptional regulatory networks. Here, we attempt to summarize and compare much of what we know about specification and maturation of myocardial lineages from studies in several different vertebrate model systems. To date, most research has focused on early specification, and although there is still more to learn about early specification, less is known about factors that promote subsequent maturation of myocardial lineages required to build the functioning adult heart.
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Affiliation(s)
- Sylvia M Evans
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Department of Medicine, University of California San Diego, 9500 Gilman Dr, La Jolla CA 92093, USA.
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45
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Zhu WZ, Xie Y, Moyes KW, Gold JD, Askari B, Laflamme MA. Neuregulin/ErbB signaling regulates cardiac subtype specification in differentiating human embryonic stem cells. Circ Res 2010; 107:776-86. [PMID: 20671236 DOI: 10.1161/circresaha.110.223917] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
RATIONALE Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) exhibit either a "working" chamber or a nodal-like phenotype. To generate optimal hESC-CM preparations for eventual clinical application in cell-based therapies, we will need to control their differentiation into these specialized cardiac subtypes. OBJECTIVE To demonstrate intact neuregulin (NRG)-1β/ErbB signaling in hESC-CMs and test the hypothesis that this signaling pathway regulates cardiac subtype abundance in hESC-CM cultures. METHODS AND RESULTS All experiments used hESC-CM cultures generated using our recently reported directed differentiation protocol. To support subsequent action potential phenotyping approaches and provide a higher-throughput method of determining cardiac subtype, we first developed and validated a novel genetic label that identifies nodal-type hESC-CMs. Next, control hESC-CM preparations were compared to those differentiated in the presence of exogenous NRG-1β, an anti-NRG-1β neutralizing antibody, or the ErbB antagonist AG1478. We used 3 independent approaches to determine the ratio of cardiac subtypes in the resultant populations: direct action potential phenotyping under current-clamp, activation of the aforementioned genetic label, and subtype-specific marker expression by RT-PCR. Using all 3 end points, we found that inhibition of NRG-1β/ErbB signaling greatly enhanced the proportion of cells showing the nodal phenotype. CONCLUSIONS NRG-1β/ErbB signaling regulates the ratio of nodal- to working-type cells in differentiating hESC-CM cultures and presumably functions similarly during early human heart development. We speculate that, by manipulating NRG-1β/ErbB signaling, it will be possible to generate preparations of enriched working-type myocytes for infarct repair, or, conversely, nodal cells for potential use in a biological pacemaker.
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Affiliation(s)
- Wei-Zhong Zhu
- Center for Cardiovascular Biology, Department of Pathology, University of Washington, Seattle, WA 98109, USA
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46
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Bakker ML, Moorman AF, Christoffels VM. The Atrioventricular Node: Origin, Development, and Genetic Program. Trends Cardiovasc Med 2010; 20:164-71. [DOI: 10.1016/j.tcm.2011.02.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 10/07/2010] [Indexed: 12/15/2022]
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47
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The Cardiac Pacemaker and Conduction System Develops From Embryonic Myocardium that Retains Its Primitive Phenotype. J Cardiovasc Pharmacol 2010; 56:6-15. [DOI: 10.1097/fjc.0b013e3181e775d3] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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48
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Miquerol L, Moreno-Rascon N, Beyer S, Dupays L, Meilhac SM, Buckingham ME, Franco D, Kelly RG. Biphasic development of the mammalian ventricular conduction system. Circ Res 2010; 107:153-61. [PMID: 20466980 DOI: 10.1161/circresaha.110.218156] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE The ventricular conduction system controls the propagation of electric activity through the heart to coordinate cardiac contraction. This system is composed of specialized cardiomyocytes organized in defined structures including central components and a peripheral Purkinje fiber network. How the mammalian ventricular conduction system is established during development remains controversial. OBJECTIVE To define the lineage relationship between cells of the murine ventricular conduction system and surrounding working myocytes. METHODS AND RESULTS A retrospective clonal analysis using the alpha-cardiac actin(nlaacZ/+) mouse line was carried out in three week old hearts. Clusters of clonally related myocytes were screened for conductive cells using connexin40-driven enhanced green fluorescent protein expression. Two classes of clusters containing conductive cells were obtained. Mixed clusters, composed of conductive and working myocytes, reveal that both cell types develop from common progenitor cells, whereas smaller unmixed clusters, composed exclusively of conductive cells, show that proliferation continues after lineage restriction to the conduction system lineage. Differences in the working component of mixed clusters between the right and left ventricles reveal distinct progenitor cell histories in these cardiac compartments. These results are supported by genetic fate mapping using Cre recombinase revealing progressive restriction of connexin40-positive myocytes to a conductive fate. CONCLUSIONS A biphasic mode of development, lineage restriction followed by limited outgrowth, underlies establishment of the mammalian ventricular conduction system.
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Affiliation(s)
- Lucile Miquerol
- Developmental Biology Institute of Marseilles-Luminy (IBDML), CNRS UMR6216 Université de la Méditerranée, Campus de Luminy, Marseille, France.
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49
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Sankova B, Machalek J, Sedmera D. Effects of mechanical loading on early conduction system differentiation in the chick. Am J Physiol Heart Circ Physiol 2010; 298:H1571-6. [DOI: 10.1152/ajpheart.00721.2009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The primary ring, a horseshoe-shaped structure situated between the left and right ventricle and connected superiorly to the atrioventricular canal, is the first specialized fast ventricular conduction pathway in the embryonic heart. It has been first defined immunohistochemically and is characterized as a region of slow myocyte proliferation. Recent studies have shown that it participates in spreading the ventricular electrical activation during stages preceding ventricular septation in the mouse, chick, and rat. Here we demonstrate its presence using optical mapping in chicks between embryonic days (ED) 3–5. We then tested the effects of hemodynamic unloading in the organ culture system upon its functionality. In ED3 hearts cultured without hemodynamic loading for 24 h, we observed a significant decrease in the percentage activated through the primary ring conduction pathway. A morphological examination revealed arrested growth, collapse, and elongation of the outflow tract and disorganized trabeculation. A similar reversal toward more primitive activation patterns was observed with culture between ED4 and ED5. This phenotype was completely rescued with the artificial loading of the ventricles with a droplet of silicone oil. We conclude that an appropriate loading is required during the early phases of the conduction system formation and maturation.
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Affiliation(s)
- Barbora Sankova
- Institute of Anatomy, First Faculty of Medicine, Charles University in Prague
- Institute of Physiology; and
- Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Jakub Machalek
- Institute of Anatomy, First Faculty of Medicine, Charles University in Prague
| | - David Sedmera
- Institute of Anatomy, First Faculty of Medicine, Charles University in Prague
- Institute of Physiology; and
- Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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50
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Abstract
Diseases of the cardiovascular system that cause sudden cardiac deaths are often caused by lethal arrhythmias that originate from defects in the cardiac conduction system. Development of the cardiac conduction system is a complex biological process that can be wrought with problems. Although several genes involved in mature conduction system function have been identified, their association with development of specific subcomponents of the cardiac conduction system remains challenging. Several transcription factors, including homeodomain proteins and T-box proteins, are essential for cardiac conduction system morphogenesis and activation or repression of key regulatory genes. In addition, several transcription factors modify expression of genes encoding the ion channel proteins that contribute to the electrophysiological properties of the conduction system and govern contraction of the surrounding myocardium. Loss of transcriptional regulation during cardiac development has detrimental effects on cardiogenesis that may lead to arrhythmias. Human genetic mutations in some of these transcription factors have been identified and are known to cause congenital heart diseases that include cardiac conduction system malformations. In this review, we summarize the contributions of several key transcription factors to specification, patterning, maturation, and function of the cardiac conduction system. Further analysis of the molecular programs involved in this process should lead to improved diagnosis and therapy of conduction system disease.
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Affiliation(s)
- Cathy J Hatcher
- Center for Molecular Cardiology, Greenberg Division of Cardiology, Weill Medical College of Cornell University, New York, NY 10065, USA.
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