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Perera T, Pius C, Niort B, Radcliffe EJ, Dibb KM, Trafford AW, Pinali C. Serial block face scanning electron microscopy reveals region-dependent remodelling of transverse tubules post-myocardial infarction. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210331. [PMID: 36189812 PMCID: PMC9527908 DOI: 10.1098/rstb.2021.0331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The highly organized transverse tubule (t-tubule) network facilitates cardiac excitation-contraction coupling and synchronous cardiac myocyte contraction. In cardiac failure secondary to myocardial infarction (MI), changes in the structure and organization of t-tubules result in impaired cardiac contractility. However, there is still little knowledge on the regional variation of t-tubule remodelling in cardiac failure post-MI. Here, we investigate post-MI t-tubule remodelling in infarct border and remote regions, using serial block face scanning electron microscopy (SBF-SEM) applied to a translationally relevant sheep ischaemia reperfusion MI model and matched controls. We performed minimally invasive coronary angioplasty of the left anterior descending artery, followed by reperfusion after 90 min to establish the MI model. Left ventricular tissues obtained from control and MI hearts eight weeks post-MI were imaged using SBF-SEM. Image analysis generated three-dimensional reconstructions of the t-tubular network in control, MI border and remote regions. Quantitative analysis revealed that the MI border region was characterized by t-tubule depletion and fragmentation, dilation of surviving t-tubules and t-tubule elongation. This study highlights region-dependent remodelling of the tubular network post-MI and may provide novel localized therapeutic targets aimed at preservation or restoration of the t-tubules to manage cardiac contractility post-MI. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'.
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Affiliation(s)
- Tharushi Perera
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, 46 Grafton Street, Manchester M13 9NT, UK
| | - Charlene Pius
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, 46 Grafton Street, Manchester M13 9NT, UK
| | - Barbara Niort
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, 46 Grafton Street, Manchester M13 9NT, UK
| | - Emma J Radcliffe
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, 46 Grafton Street, Manchester M13 9NT, UK
| | - Katharine M Dibb
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, 46 Grafton Street, Manchester M13 9NT, UK
| | - Andrew W Trafford
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, 46 Grafton Street, Manchester M13 9NT, UK
| | - Christian Pinali
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, 46 Grafton Street, Manchester M13 9NT, UK
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2
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Garay BI, Givens S, Abreu P, Liu M, Yücel D, Baik J, Stanis N, Rothermel TM, Magli A, Abrahante JE, Goloviznina NA, Soliman HAN, Dhoke NR, Kyba M, Alford PW, Dudley SC, van Berlo JH, Ogle B, Perlingeiro RRC. Dual inhibition of MAPK and PI3K/AKT pathways enhances maturation of human iPSC-derived cardiomyocytes. Stem Cell Reports 2022; 17:2005-2022. [PMID: 35931076 PMCID: PMC9481895 DOI: 10.1016/j.stemcr.2022.07.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 07/05/2022] [Accepted: 07/06/2022] [Indexed: 01/25/2023] Open
Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) provide great opportunities for mechanistic dissection of human cardiac pathophysiology; however, hiPSC-CMs remain immature relative to the adult heart. To identify novel signaling pathways driving the maturation process during heart development, we analyzed published transcriptional and epigenetic datasets from hiPSC-CMs and prenatal and postnatal human hearts. These analyses revealed that several components of the MAPK and PI3K-AKT pathways are downregulated in the postnatal heart. Here, we show that dual inhibition of these pathways for only 5 days significantly enhances the maturation of day 30 hiPSC-CMs in many domains: hypertrophy, multinucleation, metabolism, T-tubule density, calcium handling, and electrophysiology, many equivalent to day 60 hiPSC-CMs. These data indicate that the MAPK/PI3K/AKT pathways are involved in cardiomyocyte maturation and provide proof of concept for the manipulation of key signaling pathways for optimal hiPSC-CM maturation, a critical aspect of faithful in vitro modeling of cardiac pathologies and subsequent drug discovery.
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Affiliation(s)
- Bayardo I Garay
- Lillehei Heart Institute (LHI), Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA; Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - Sophie Givens
- Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA; Stem Cell Institute, University of Minnesota, Minneapolis, MN, USA
| | - Phablo Abreu
- Lillehei Heart Institute (LHI), Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Man Liu
- Lillehei Heart Institute (LHI), Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Doğacan Yücel
- Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - June Baik
- Lillehei Heart Institute (LHI), Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Noah Stanis
- Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA
| | | | - Alessandro Magli
- Lillehei Heart Institute (LHI), Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Juan E Abrahante
- University of Minnesota Informatics Institute, Minneapolis, MN, USA
| | - Natalya A Goloviznina
- Molecular, Cellular, Developmental Biology and Genetics, University of Minnesota, Minneapolis, MN, USA; LHI, Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Hossam A N Soliman
- LHI, Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Neha R Dhoke
- Lillehei Heart Institute (LHI), Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Michael Kyba
- Stem Cell Institute, University of Minnesota, Minneapolis, MN, USA; Molecular, Cellular, Developmental Biology and Genetics, University of Minnesota, Minneapolis, MN, USA; LHI, Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Patrick W Alford
- Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Samuel C Dudley
- Lillehei Heart Institute (LHI), Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Jop H van Berlo
- Lillehei Heart Institute (LHI), Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA; Stem Cell Institute, University of Minnesota, Minneapolis, MN, USA; Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Brenda Ogle
- Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA; Stem Cell Institute, University of Minnesota, Minneapolis, MN, USA
| | - Rita R C Perlingeiro
- Lillehei Heart Institute (LHI), Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA; Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA; Stem Cell Institute, University of Minnesota, Minneapolis, MN, USA; Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA; Molecular, Cellular, Developmental Biology and Genetics, University of Minnesota, Minneapolis, MN, USA.
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3
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Magat J, Yon M, Bihan-Poudec Y, Ozenne V. A groupwise registration and tractography framework for cardiac myofiber architecture description by diffusion MRI: An application to the ventricular junctions. PLoS One 2022; 17:e0271279. [PMID: 35849598 PMCID: PMC9292118 DOI: 10.1371/journal.pone.0271279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 06/27/2022] [Indexed: 11/19/2022] Open
Abstract
Background Knowledge of the normal myocardial–myocyte orientation could theoretically allow the definition of relevant quantitative biomarkers in clinical routine to diagnose heart pathologies. A whole heart diffusion tensor template representative of the global myofiber organization over species is therefore crucial for comparisons across populations. In this study, we developed a groupwise registration and tractography framework to resolve the global myofiber arrangement of large mammalian sheep hearts. To demonstrate the potential application of the proposed method, a novel description of sub-regions in the intraventricular septum is presented. Methods Three explanted sheep (ovine) hearts (size ~12×8×6 cm3, heart weight ~ 150 g) were perfused with contrast agent and fixative and imaged in a 9.4T magnet. A group-wise registration of high-resolution anatomical and diffusion-weighted images were performed to generate anatomical and diffusion tensor templates. Diffusion tensor metrics (eigenvalues, eigenvectors, fractional anisotropy …) were computed to provide a quantitative and spatially-resolved analysis of cardiac microstructure. Then tractography was performed using deterministic and probabilistic algorithms and used for different purposes: i) Visualization of myofiber architecture, ii) Segmentation of sub-area depicting the same fiber organization, iii) Seeding and Tract Editing. Finally, dissection was performed to confirm the existence of macroscopic structures identified in the diffusion tensor template. Results The template creation takes advantage of high-resolution anatomical and diffusion-weighted images obtained at an isotropic resolution of 150 μm and 600 μm respectively, covering ventricles and atria and providing information on the normal myocardial architecture. The diffusion metric distributions from the template were found close to the one of the individual samples validating the registration procedure. Small new sub-regions exhibiting spatially sharp variations in fiber orientation close to the junctions of the septum and ventricles were identified. Each substructure was defined and represented using streamlines. The existence of a fiber-bundles in the posterior junction was validated by anatomical dissection. A complex structural organization of the anterior junction in comparison to the posterior junction was evidenced by the high-resolution acquisition. Conclusions A new framework combining cardiac template generation and tractography was applied on the whole sheep heart. The framework can be used for anatomical investigation, characterization of microstructure and visualization of myofiber orientation across samples. Finally, a novel description of the ventricular junction in large mammalian sheep hearts was proposed.
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Affiliation(s)
- Julie Magat
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux Université, Bordeaux, France
- Centre de recherche Cardio-Thoracique de Bordeaux, Univ. Bordeaux, U1045, Bordeaux, France
- INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France
| | - Maxime Yon
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux Université, Bordeaux, France
- Centre de recherche Cardio-Thoracique de Bordeaux, Univ. Bordeaux, U1045, Bordeaux, France
- INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France
| | - Yann Bihan-Poudec
- Institut des Sciences Cognitives Marc Jeannerod, CNRS UMR 5229, Université Claude Bernard Lyon I, Bron, France
| | - Valéry Ozenne
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux Université, Bordeaux, France
- Centre de recherche Cardio-Thoracique de Bordeaux, Univ. Bordeaux, U1045, Bordeaux, France
- INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, CNRS/Université de Bordeaux, Bordeaux, France
- * E-mail:
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Švecová O, Bébarová M, Šimurdová M, Šimurda J. Fraction of the T-Tubular Membrane as an Important Parameter in Cardiac Cellular Electrophysiology: A New Way of Estimation. Front Physiol 2022; 13:837239. [PMID: 35620609 PMCID: PMC9127156 DOI: 10.3389/fphys.2022.837239] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 04/15/2022] [Indexed: 12/02/2022] Open
Abstract
The transverse-axial tubular system (t-tubules) plays an essential role in excitation-contraction coupling in cardiomyocytes. Its remodelling is associated with various cardiac diseases. Numerous attempts were made to analyse characteristics essential for proper understanding of the t-tubules and their impact on cardiac cell function in health and disease. The currently available methodical approaches related to the fraction of the t-tubular membrane area produce diverse data. The widely used detubulation techniques cause irreversible cell impairment, thus, distinct cell samples have to be used for estimation of t-tubular parameters in untreated and detubulated cells. Our proposed alternative method is reversible and allows repetitive estimation of the fraction of t-tubular membrane (f t) in cardiomyocytes using short-term perfusion of the measured cell with a low-conductive isotonic sucrose solution. It results in a substantial increase in the electrical resistance of t-tubular lumen, thus, electrically separating the surface and t-tubular membranes. Using the whole-cell patch-clamp measurement and the new approach in enzymatically isolated rat atrial and ventricular myocytes, a set of data was measured and evaluated. The analysis of the electrical equivalent circuit resulted in the establishment of criteria for excluding measurements in which perfusion with a low conductivity solution did not affect the entire cell surface. As expected, the final average f t in ventricular myocytes (0.337 ± 0.017) was significantly higher than that in atrial myocytes (0.144 ± 0.015). The parameter f t could be estimated repetitively in a particular cell (0.345 ± 0.021 and 0.347 ± 0.023 in ventricular myocytes during the first and second sucrose perfusion, respectively). The new method is fast, simple, and leaves the measured cell intact. It can be applied in the course of experiments for which it is useful to estimate both the surface and t-tubular capacitance/area in a particular cell.
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Affiliation(s)
- Olga Švecová
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Markéta Bébarová
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Milena Šimurdová
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Jiří Šimurda
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czechia
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Prasad V, Makkaoui N, Rajan R, Patel A, Mainali B, Bagchi P, Kumar R, Rogers J, Diamond J, Maxwell JT. Loss of cardiac myosin light chain kinase contributes to contractile dysfunction in right ventricular pressure overload. Physiol Rep 2022; 10:e15238. [PMID: 35384363 PMCID: PMC8981447 DOI: 10.14814/phy2.15238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 03/03/2022] [Accepted: 03/06/2022] [Indexed: 06/14/2023] Open
Abstract
Nearly 1 in every 100 children born have a congenital heart defect. Many of these defects primarily affect the right heart causing pressure overload of the right ventricle (RV). The RV maintains function by adapting to the increased pressure; however, many of these adaptations eventually lead to RV hypertrophy and failure. In this study, we aim to identify the cellular and molecular mechanisms of these adaptions. We utilized a surgical animal model of pulmonary artery banding (PAB) in juvenile rats that has been shown to accurately recapitulate the physiology of right ventricular pressure overload in young hearts. Using this model, we examined changes in cardiac myocyte protein expression as a result of pressure overload with mass spectrometry 4 weeks post-banding. We found pressure overload of the RV induced significant downregulation of cardiac myosin light chain kinase (cMLCK). Single myocyte calcium and contractility recordings showed impaired contraction and relaxation in PAB RV myocytes, consistent with the loss of cMLCK. In the PAB myocytes, calcium transients were of smaller amplitude and decayed at a slower rate compared to controls. We also identified miR-200c, which has been shown to regulate cMLCK expression, as upregulated in the RV in response to pressure overload. These results indicate the loss of cMLCK is a critical maladaptation of the RV to pressure overload and represents a novel target for therapeutic approaches to treat RV hypertrophy and failure associated with congenital heart defects.
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Affiliation(s)
- Vidhya Prasad
- Division of Pediatric CardiologyDepartment of PediatricsEmory University School of MedicineAtlantaGeorgiaUSA
- Children’s Heart Research & Outcomes (HeRO) CenterChildren’s Healthcare of Atlanta & Emory UniversityAtlantaGeorgiaUSA
| | - Nour Makkaoui
- Division of Pediatric CardiologyDepartment of PediatricsEmory University School of MedicineAtlantaGeorgiaUSA
- Children’s Heart Research & Outcomes (HeRO) CenterChildren’s Healthcare of Atlanta & Emory UniversityAtlantaGeorgiaUSA
| | - Rohan Rajan
- Emory University College of Arts and SciencesAtlantaGeorgiaUSA
| | - Alisha Patel
- Emory University College of Arts and SciencesAtlantaGeorgiaUSA
| | - Bipul Mainali
- Emory University College of Arts and SciencesAtlantaGeorgiaUSA
| | - Pritha Bagchi
- Department of BiochemistryEmory University School of MedicineAtlantaGeorgiaUSA
| | - Rhea Kumar
- Emory University College of Arts and SciencesAtlantaGeorgiaUSA
| | - Julia Rogers
- Emory University College of Arts and SciencesAtlantaGeorgiaUSA
| | - Jake Diamond
- Emory University College of Arts and SciencesAtlantaGeorgiaUSA
| | - Joshua T. Maxwell
- Division of Pediatric CardiologyDepartment of PediatricsEmory University School of MedicineAtlantaGeorgiaUSA
- Children’s Heart Research & Outcomes (HeRO) CenterChildren’s Healthcare of Atlanta & Emory UniversityAtlantaGeorgiaUSA
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6
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Approaches to Optimize Stem Cell-Derived Cardiomyocyte Maturation and Function. CURRENT STEM CELL REPORTS 2021. [DOI: 10.1007/s40778-021-00197-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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7
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T-tubule remodeling in human hypertrophic cardiomyopathy. J Muscle Res Cell Motil 2020; 42:305-322. [PMID: 33222034 PMCID: PMC8332592 DOI: 10.1007/s10974-020-09591-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 10/22/2020] [Indexed: 11/17/2022]
Abstract
The highly organized transverse T-tubule membrane system represents the ultrastructural substrate for excitation–contraction coupling in ventricular myocytes. While the architecture and function of T-tubules have been well described in animal models, there is limited morpho-functional data on T-tubules in human myocardium. Hypertrophic cardiomyopathy (HCM) is a primary disease of the heart muscle, characterized by different clinical presentations at the various stages of its progression. Most HCM patients, indeed, show a compensated hypertrophic disease (“non-failing hypertrophic phase”), with preserved left ventricular function, and only a small subset of individuals evolves into heart failure (“end stage HCM”). In terms of T-tubule remodeling, the “end-stage” disease does not differ from other forms of heart failure. In this review we aim to recapitulate the main structural features of T-tubules during the “non-failing hypertrophic stage” of human HCM by revisiting data obtained from human myectomy samples. Moreover, by comparing pathological changes observed in myectomy samples with those introduced by acute (experimentally induced) detubulation, we discuss the role of T-tubular disruption as a part of the complex excitation–contraction coupling remodeling process that occurs during disease progression. Lastly, we highlight how T-tubule morpho-functional changes may be related to patient genotype and we discuss the possibility of a primitive remodeling of the T-tubule system in rare HCM forms associated with genes coding for proteins implicated in T-tubule structural integrity, formation and maintenance.
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8
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Sanchez-Alonso JL, Loucks A, Schobesberger S, van Cromvoirt AM, Poulet C, Chowdhury RA, Trayanova N, Gorelik J. Nanoscale regulation of L-type calcium channels differentiates between ischemic and dilated cardiomyopathies. EBioMedicine 2020; 57:102845. [PMID: 32580140 PMCID: PMC7317229 DOI: 10.1016/j.ebiom.2020.102845] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/19/2020] [Accepted: 06/03/2020] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Subcellular localization and function of L-type calcium channels (LTCCs) play an important role in regulating contraction of cardiomyocytes. Understanding how this is affected by the disruption of transverse tubules during heart failure could lead to new insights into the disease. METHODS Cardiomyocytes were isolated from healthy donor hearts, as well as from patients with cardiomyopathies and with left ventricular assist devices. Scanning ion conductance and confocal microscopy was used to study membrane structures in the cells. Super-resolution scanning patch-clamp was used to examine LTCC function in different microdomains. Computational modeling predicted the impact of these changes to arrhythmogenesis at the whole-heart level. FINDINGS We showed that loss of structural organization in failing myocytes leads to re-distribution of functional LTCCs from the T-tubules to the sarcolemma. In ischemic cardiomyopathy, the increased LTCC open probability in the T-tubules depends on the phosphorylation by protein kinase A, whereas in dilated cardiomyopathy, the increased LTCC opening probability in the sarcolemma results from enhanced phosphorylation by calcium-calmodulin kinase II. LVAD implantation corrected LTCCs pathophysiological activity, although it did not improve their distribution. Using computational modeling in a 3D anatomically-realistic human ventricular model, we showed how LTCC location and activity can trigger heart rhythm disorders of different severity. INTERPRETATION Our findings demonstrate that LTCC redistribution and function differentiate between disease aetiologies. The subcellular changes observed in specific microdomains could be the consequence of the action of distinct protein kinases. FUNDING This work was supported by NIH grant (ROI-HL 126802 to NT-JG) and British Heart Foundation (grant RG/17/13/33173 to JG, project grant PG/16/17/32069 to RAC). Funders had no role in study design, data collection, data analysis, interpretation, writing of the report.
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Affiliation(s)
- Jose L Sanchez-Alonso
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Alexandra Loucks
- Department of Biomedical Engineering and Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sophie Schobesberger
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Ankie M van Cromvoirt
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Claire Poulet
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Rasheda A Chowdhury
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK
| | - Natalia Trayanova
- Department of Biomedical Engineering and Alliance for Cardiovascular Diagnostic and Treatment Innovation, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Julia Gorelik
- Department of Cardiovascular Sciences, Imperial Centre for Translational and Experimental Medicine, National Heart and Lung Institute, Imperial College London, London W120NN, UK.
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Crossman DJ, Jayasinghe ID, Soeller C. Transverse tubule remodelling: a cellular pathology driven by both sides of the plasmalemma? Biophys Rev 2017; 9:919-929. [PMID: 28695473 DOI: 10.1007/s12551-017-0273-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 06/06/2017] [Indexed: 01/10/2023] Open
Abstract
Transverse (t)-tubules are invaginations of the plasma membrane that form a complex network of ducts, 200-400 nm in diameter depending on the animal species, that penetrates deep within the cardiac myocyte, where they facilitate a fast and synchronous contraction across the entire cell volume. There is now a large body of evidence in animal models and humans demonstrating that pathological distortion of the t-tubule structure has a causative role in the loss of myocyte contractility that underpins many forms of heart failure. Investigations into the molecular mechanisms of pathological t-tubule remodelling to date have focused on proteins residing in the intracellular aspect of t-tubule membrane that form linkages between the membrane and myocyte cytoskeleton. In this review, we shed light on the mechanisms of t-tubule remodelling which are not limited to the intracellular side. Our recent data have demonstrated that collagen is an integral part of the t-tubule network and that it increases within the tubules in heart failure, suggesting that a fibrotic mechanism could drive cardiac junctional remodelling. We examine the evidence that the linkages between the extracellular matrix, t-tubule membrane and cellular cytoskeleton should be considered as a whole when investigating the mechanisms of t-tubule pathology in the failing heart.
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Affiliation(s)
- David J Crossman
- Department of Physiology, University of Auckland, Auckland, New Zealand.
| | | | - Christian Soeller
- Department of Physiology, University of Auckland, Auckland, New Zealand
- Biomedical Physics, University of Exeter, Exeter, UK
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10
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Morphometric Analysis of Human Embryonic Stem Cell-Derived Ventricular Cardiomyocytes: Determining the Maturation State of a Population by Quantifying Parameters in Individual Cells. Stem Cells Int 2015; 2015:586908. [PMID: 26351464 PMCID: PMC4553338 DOI: 10.1155/2015/586908] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 07/13/2015] [Accepted: 07/22/2015] [Indexed: 11/24/2022] Open
Abstract
Quantitative methods were established to determine the level of maturation of human embryonic stem cell-derived ventricular cardiomyocytes (hESC-vCMs) that were treated with different metabolic stimulants (i.e., isoproterenol and oleic acid) during early differentiation. Cells were double-immunolabeled with α-actinin and COX IV antibodies, to label the myofibrils and mitochondria, respectively, after which images were acquired via confocal microscopy. In order to determine the extent of differentiation, image analysis protocols were then used to quantify cell shape and area, as well as the degree of myofibrillar organization and intercalation of mitochondria between the myofibrils within the cells. We demonstrated that oleic acid or isoproterenol alone, or a combination of the two, induced a more elongated hESC-vCM phenotype than the untreated controls. In addition, cells treated with isoproterenol alone exhibited a similar level of myofibrillar organization as the controls, but those treated with oleic acid with/without isoproterenol exhibited a more organized (parallel) orientation of myofibrils. The combined isoproterenol/oleic acid treatment also resulted in enhanced intercalation of mitochondria between the myofibrils. We suggest that these quantitative morphometric methods might serve as simple and effective tools that can be utilized in the determination of the level of structural maturation of hESC-vCMs.
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11
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Measuring the metrics: Correlating t-tubule structure and muscle contraction in the intact heart. J Mol Cell Cardiol 2015; 85:153-4. [PMID: 26031703 DOI: 10.1016/j.yjmcc.2015.05.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 05/22/2015] [Indexed: 11/20/2022]
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12
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Chen B, Zhang C, Guo A, Song LS. In situ single photon confocal imaging of cardiomyocyte T-tubule system from Langendorff-perfused hearts. Front Physiol 2015; 6:134. [PMID: 25999861 PMCID: PMC4422017 DOI: 10.3389/fphys.2015.00134] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 04/15/2015] [Indexed: 12/24/2022] Open
Abstract
Transverse tubules (T-tubules) are orderly invaginations of the sarcolemma in mammalian cardiomyocytes. The integrity of T-tubule architecture is critical for cardiac excitation–contraction coupling function. T-tubule remodeling is recognized as a key player in cardiac dysfunction. Early studies on T-tubule structure were based on electron microscopy, which uncovered important information about the T-tubule architecture. The advent of fluorescent membrane probes allowed the application of confocal microscopy to investigations of T-tubule structure. Studies have now been extended beyond single cardiomyocytes to examine the T-tubule network in intact hearts through in situ confocal imaging of Langendorff-perfused hearts. This technique has allowed visualization of T-tubule organization in their natural habitat, avoiding the damage induced by isolation of cardiomyocytes. Additionally, it is possible to obtain T-tubule images in different subepicardial regions in a single intact heart. We review how this state-of-the-art imaging technique has provided important mechanistic insights into maturation of T-tubules in developing hearts and defined the role of T-tubule remodeling in development and progression of heart failure.
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Affiliation(s)
- Biyi Chen
- Division of Cardiovascular Medicine, Department of Internal Medicine, Francois M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa Iowa City, IA, USA
| | - Caimei Zhang
- Division of Cardiovascular Medicine, Department of Internal Medicine, Francois M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa Iowa City, IA, USA
| | - Ang Guo
- Division of Cardiovascular Medicine, Department of Internal Medicine, Francois M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa Iowa City, IA, USA
| | - Long-Sheng Song
- Division of Cardiovascular Medicine, Department of Internal Medicine, Francois M. Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa Iowa City, IA, USA
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13
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Crossman DJ, Young AA, Ruygrok PN, Nason GP, Baddelely D, Soeller C, Cannell MB. T-tubule disease: Relationship between t-tubule organization and regional contractile performance in human dilated cardiomyopathy. J Mol Cell Cardiol 2015; 84:170-8. [PMID: 25953258 DOI: 10.1016/j.yjmcc.2015.04.022] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 04/27/2015] [Accepted: 04/28/2015] [Indexed: 11/30/2022]
Abstract
Evidence from animal models suggest that t-tubule changes may play an important role in the contractile deficit associated with heart failure. However samples are usually taken at random with no regard as to regional variability present in failing hearts which leads to uncertainty in the relationship between contractile performance and possible t-tubule derangement. Regional contraction in human hearts was measured by tagged cine MRI and model fitting. At transplant, failing hearts were biopsy sampled in identified regions and immunocytochemistry was used to label t-tubules and sarcomeric z-lines. Computer image analysis was used to assess 5 different unbiased measures of t-tubule structure/organization. In regions of failing hearts that showed good contractile performance, t-tubule organization was similar to that seen in normal hearts, with worsening structure correlating with the loss of regional contractile performance. Statistical analysis showed that t-tubule direction was most highly correlated with local contractile performance, followed by the amplitude of the sarcomeric peak in the Fourier transform of the t-tubule image. Other area based measures were less well correlated. We conclude that regional contractile performance in failing human hearts is strongly correlated with the local t-tubule organization. Cluster tree analysis with a functional definition of failing contraction strength allowed a pathological definition of 't-tubule disease'. The regional variability in contractile performance and cellular structure is a confounding issue for analysis of samples taken from failing human hearts, although this may be overcome with regional analysis by using tagged cMRI and biopsy mapping.
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Affiliation(s)
| | - Alistair A Young
- Department of Anatomy with Radiology, University of Auckland, New Zealand
| | - Peter N Ruygrok
- Department of Cardiology, Auckland City Hospital, New Zealand
| | - Guy P Nason
- School of Mathematics, University of Bristol, UK
| | - David Baddelely
- Department of Physiology, University of Auckland, New Zealand
| | | | - Mark B Cannell
- Department of Physiology, University of Auckland, New Zealand; School of Physiology and Pharmacology, University of Bristol, UK.
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14
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Moench I, Lopatin AN. Ca(2+) homeostasis in sealed t-tubules of mouse ventricular myocytes. J Mol Cell Cardiol 2014; 72:374-83. [PMID: 24787472 DOI: 10.1016/j.yjmcc.2014.04.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 04/15/2014] [Accepted: 04/18/2014] [Indexed: 10/25/2022]
Abstract
We have recently shown that in mouse ventricular myocytes, t-tubules can be quickly and tightly sealed during the resolution of hyposmotic shock of physiologically relevant magnitude. Sealing of t-tubules is associated with trapping extracellular solution inside the myocytes but the ionic homeostasis of sealed t-tubules and the consequences of potential transtubular ion fluxes remain unknown. In this study we investigated the dynamics of Ca(2+) movements associated with sealing of t-tubules. The data show that under normal conditions sealed t-tubules contain Ca(2+) at concentrations below 100μM. However, blockade of voltage-dependent Ca(2+) channels with 10μM nicardipine, or increasing extracellular concentration of K(+) from 5.4mM to 20mM led to several fold increase in concentration of t-tubular Ca(2+). Alternatively, the release of Ca(2+) from sarcoplasmic reticulum using 10mM caffeine led to the restoration of t-tubular Ca(2+) towards extracellular levels within few seconds. Sealing of t-tubules in the presence of extracellular 1.5mM Ca(2+) and 5.4mM extracellular K(+) led to occasional and sporadic intracellular Ca(2+) transients. In contrast, sealing of t-tubules in the presence of 10mM caffeine was characterized by a significant long lasting increase in intracellular Ca(2+). The effect was completely abolished in the absence of extracellular Ca(2+) and significantly reduced in pre-detubulated myocytes but was essentially preserved in the presence of mitochondrial decoupler dinitrophenol. This study shows that sealed t-tubules are capable of highly regulated transport of Ca(2+) and present a major route for Ca(2+) influx into the cytosol during sealing process.
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Affiliation(s)
- I Moench
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - A N Lopatin
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA.
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15
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Effect of ion concentration changes in the limited extracellular spaces on sarcolemmal ion transport and Ca2+ turnover in a model of human ventricular cardiomyocyte. Int J Mol Sci 2013; 14:24271-92. [PMID: 24351816 PMCID: PMC3876110 DOI: 10.3390/ijms141224271] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 11/12/2013] [Accepted: 11/19/2013] [Indexed: 11/24/2022] Open
Abstract
We have developed a computer model of human cardiac ventricular myocyte (CVM), including t-tubular and cleft spaces with the aim of evaluating the impact of accumulation-depletion of ions in restricted extracellular spaces on transmembrane ion transport and ionic homeostasis in human CVM. The model was based on available data from human CVMs. Under steady state, the effect of ion concentration changes in extracellular spaces on [Ca2+]i-transient was explored as a function of critical fractions of ion transporters in t-tubular membrane (not documented for human CVM). Depletion of Ca2+ and accumulation of K+ occurring in extracellular spaces slightly affected the transmembrane Ca2+ flux, but not the action potential duration (APD90). The [Ca2+]i-transient was reduced (by 2%–9%), depending on the stimulation frequency, the rate of ion exchange between t-tubules and clefts and fractions of ion-transfer proteins in the t-tubular membrane. Under non-steady state, the responses of the model to changes of stimulation frequency were analyzed. A sudden increase of frequency (1–2.5 Hz) caused a temporal decrease of [Ca2+] in both extracellular spaces, a reduction of [Ca2+]i-transient (by 15%) and APD90 (by 13 ms). The results reveal different effects of activity-related ion concentration changes in human cardiac t-tubules (steady-state effects) and intercellular clefts (transient effects) in the modulation of membrane ion transport and Ca2+ turnover.
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16
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Ferrantini C, Crocini C, Coppini R, Vanzi F, Tesi C, Cerbai E, Poggesi C, Pavone FS, Sacconi L. The transverse-axial tubular system of cardiomyocytes. Cell Mol Life Sci 2013; 70:4695-710. [PMID: 23846763 PMCID: PMC11113601 DOI: 10.1007/s00018-013-1410-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 06/03/2013] [Accepted: 06/13/2013] [Indexed: 10/26/2022]
Abstract
A characteristic histological feature of striated muscle cells is the presence of deep invaginations of the plasma membrane (sarcolemma), most commonly referred to as T-tubules or the transverse-axial tubular system (TATS). TATS mediates the rapid spread of the electrical signal (action potential) to the cell core triggering Ca(2+) release from the sarcoplasmic reticulum, ultimately inducing myofilament contraction (excitation-contraction coupling). T-tubules, first described in vertebrate skeletal muscle cells, have also been recognized for a long time in mammalian cardiac ventricular myocytes, with a structure and a function that in recent years have been shown to be far more complex and pivotal for cardiac function than initially thought. Renewed interest in T-tubule function stems from the loss and disorganization of T-tubules found in a number of pathological conditions including human heart failure (HF) and dilated and hypertrophic cardiomyopathies, as well as in animal models of HF, chronic ischemia and atrial fibrillation. Disease-related remodeling of the TATS leads to asynchronous and inhomogeneous Ca(2+)-release, due to the presence of orphan ryanodine receptors that have lost their coupling with the dihydropyridine receptors and are either not activated or activated with a delay. Here, we review the physiology of the TATS, focusing first on the relationship between function and structure, and then describing T-tubular remodeling and its reversal in disease settings and following effective therapeutic approaches.
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Affiliation(s)
- C. Ferrantini
- Division of Physiology, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
| | - C. Crocini
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
| | - R. Coppini
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
- Division of Pharmacology, Department “NeuroFarBa”, University of Florence, Florence, Italy
| | - F. Vanzi
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- Department of Biology, University of Florence, Florence, Italy
| | - C. Tesi
- Division of Physiology, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
| | - E. Cerbai
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
- Division of Pharmacology, Department “NeuroFarBa”, University of Florence, Florence, Italy
| | - C. Poggesi
- Division of Physiology, Department of Clinical and Experimental Medicine, University of Florence, Florence, Italy
- Centre of Molecular Medicine (C.I.M.M.B.A.), University of Florence, Florence, Italy
| | - F. S. Pavone
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- Department of Physics and Astronomy, University of Florence, Sesto Fiorentino, Italy
- National Institute of Optics (INO), National Research Council (CNR), Florence, Italy
| | - L. Sacconi
- European Laboratory for Non-Linear Spectroscopy (LENS), University of Florence, Sesto Fiorentino, Italy
- National Institute of Optics (INO), National Research Council (CNR), Florence, Italy
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17
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Pinali C, Bennett H, Davenport JB, Trafford AW, Kitmitto A. Three-Dimensional Reconstruction of Cardiac Sarcoplasmic Reticulum Reveals a Continuous Network Linking Transverse-Tubules. Circ Res 2013; 113:1219-30. [DOI: 10.1161/circresaha.113.301348] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rationale:
The organization of the transverse-tubular (t-t) system and relationship to the sarcoplasmic reticulum (SR) underpins cardiac excitation–contraction coupling. The architecture of the SR, and relationship with the t-ts, is not well characterized at the whole-cell level. Furthermore, little is known regarding changes to SR ultrastructure in heart failure.
Objective:
The aim of this study was to unravel interspecies differences and commonalities between the relationship of SR and t-t networks within cardiac myocytes, as well as the modifications that occur in heart failure, using a novel high-resolution 3-dimensional (3D) imaging technique.
Methods and Results:
Using serial block face imaging coupled with scanning electron microscopy and image analysis, we have generated 3D reconstructions of whole cardiomyocytes from sheep and rat left ventricle, revealing that the SR forms a continuous network linking t-ts throughout the cell in both species. In sheep, but not rat, the SR has an intimate relationship with the sarcolemma forming junctional domains. 3D reconstructions also reveal details of the sheep t-t system. Using a model of tachypacing-induced heart failure, we show that there are populations of swollen and collapsed t-ts, patches of SR tangling, and disorder with rearrangement of the mitochondria.
Conclusions:
We provide the first high-resolution 3D structure of the SR network showing that it forms a cell-wide communication pipeline facilitating Ca
2+
diffusion, buffering, and synchronicity. The distribution of the SR within the cell is related to interspecies differences in excitation–contraction coupling, and we report the first detailed analysis of SR remodeling as a result of heart failure.
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Affiliation(s)
- Christian Pinali
- From the Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, United Kingdom
| | - Hayley Bennett
- From the Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, United Kingdom
| | - J. Bernard Davenport
- From the Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, United Kingdom
| | - Andrew W. Trafford
- From the Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, United Kingdom
| | - Ashraf Kitmitto
- From the Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, United Kingdom
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18
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Expression and localization of TRPC proteins in rat ventricular myocytes at various developmental stages. Cell Tissue Res 2013; 355:201-12. [PMID: 24146259 DOI: 10.1007/s00441-013-1733-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 09/02/2013] [Indexed: 12/22/2022]
Abstract
Growing evidence indicates that transient receptor potential canonical (TRPC) channels play important roles in various Ca(2+)-mediated physiological and pathophysiological processes, including development. Many types of TRPC proteins are expressed in the heart. However, limited data are available comparing the expression and localization among TRPC proteins in the ventricular myocyte at various developmental stages. Our purpose is to investigate the expression and localization profile of TRPC proteins in ventricular myocytes of fetal (18.5 days), neonatal (< 24 h after birth) and adult (8 week old) rats. Western blotting, immunofluorescence and confocal laser scanning microscopy were employed. TRPC1/3-6 proteins were expressed in the rat ventricle throughout the three developmental stages. The expression profile of TRPC1/3/4 in the ventricle followed an upward trend from the fetus to the adult. By contrast, TRPC6 in the ventricle was expressed at the highest level in the fetal group and was sharply down-regulated immediately after birth. TRPC5 expression in the ventricle did not change significantly during the three stages. TRPC1/3/5/6 proteins were localized to the T-tubule and TRPC1/3/4/6 to intercalated disks in adult myocytes. The wide spatiotemporal overlap and dynamic regulation of TRPC expression in ventricular myocytes indicates potential complex combinations and redundancy of native TRPC proteins in the heart and gives important clues for further investigations into the exact subunit compositions and functional properties of native TRPC channels in the heart.
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19
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Trafford AW, Clarke JD, Richards MA, Eisner DA, Dibb KM. Calcium signalling microdomains and the t-tubular system in atrial mycoytes: potential roles in cardiac disease and arrhythmias. Cardiovasc Res 2013; 98:192-203. [PMID: 23386275 DOI: 10.1093/cvr/cvt018] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The atria contribute 25% to ventricular stroke volume and are the site of the commonest cardiac arrhythmia, atrial fibrillation (AF). The initiation of contraction in the atria is similar to that in the ventricle involving a systolic rise of intracellular Ca(2+) concentration ([Ca(2+)](i)). There are, however, substantial inter-species differences in the way systolic Ca(2+) is regulated in atrial cells. These differences are a consequence of a well-developed and functionally relevant transverse (t)-tubule network in the atria of large mammals, including humans, and its virtual absence in smaller laboratory species such as the rat. Where T-tubules are absent, the systolic Ca(2+) transient results from a 'fire-diffuse-fire' sequential recruitment of Ca(2+) release sites from the cell edge to the centre and hence marked spatiotemporal heterogeneity of systolic Ca(2+). Conversely, the well-developed T-tubule network in large mammals ensures a near synchronous rise of [Ca(2+)](i). In addition to synchronizing the systolic rise of [Ca(2+)](i), the presence of T-tubules in the atria of large mammals, by virtue of localization of the L-type Ca(2+) channels and Na(+)-Ca(2+) exchanger antiporters on the T-tubules, may serve to, respectively, accelerate changes in the amplitude of the systolic Ca(2+) transient during inotropic manoeuvres and lower diastolic [Ca(2+)](i). On the other hand, the presence of T-tubules and hence wider cellular distribution of the Na(+)-Ca(2+) exchanger may predispose the atria of large mammals to Ca(2+)-dependent delayed afterdepolarizations (DADs); this may be a determining factor in why the atria of large mammals spontaneously develop and maintain AF.
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Affiliation(s)
- Andrew W Trafford
- Unit of Cardiac Physiology, Manchester Academic Health Science Centre, Institute of Cardiovascular Science, University of Manchester, 3.23 Core Technology Facility, 46 Grafton Street, Manchester M13 9PT, UK
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20
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Atmanli A, Domian IJ. Generation of aligned functional myocardial tissue through microcontact printing. J Vis Exp 2013:e50288. [PMID: 23542789 DOI: 10.3791/50288] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Advanced heart failure represents a major unmet clinical challenge, arising from the loss of viable and/or fully functional cardiac muscle cells. Despite optimum drug therapy, heart failure represents a leading cause of mortality and morbidity in the developed world. A major challenge in drug development is the identification of cellular assays that accurately recapitulate normal and diseased human myocardial physiology in vitro. Likewise, the major challenges in regenerative cardiac biology revolve around the identification and isolation of patient-specific cardiac progenitors in clinically relevant quantities. These cells have to then be assembled into functional tissue that resembles the native heart tissue architecture. Microcontact printing allows for the creation of precise micropatterned protein shapes that resemble structural organization of the heart, thus providing geometric cues to control cell adhesion spatially. Herein we describe our approach for the isolation of highly purified myocardial cells from pluripotent stem cells differentiating in vitro, the generation of cell growth surfaces micropatterned with extracellular matrix proteins, and the assembly of the stem cell-derived cardiac muscle cells into anisotropic myocardial tissue.
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Affiliation(s)
- Ayhan Atmanli
- Cardiovascular Research Center, Massachusetts General Hospital and Harvard Medical School
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21
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Guo A, Zhang C, Wei S, Chen B, Song LS. Emerging mechanisms of T-tubule remodelling in heart failure. Cardiovasc Res 2013; 98:204-15. [PMID: 23393229 DOI: 10.1093/cvr/cvt020] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cardiac excitation-contraction coupling occurs primarily at the sites of transverse (T)-tubule/sarcoplasmic reticulum junctions. The orderly T-tubule network guarantees the instantaneous excitation and synchronous activation of nearly all Ca(2+) release sites throughout the large ventricular myocyte. Because of the critical roles played by T-tubules and the array of channels and transporters localized to the T-tubule membrane network, T-tubule architecture has recently become an area of considerable research interest in the cardiovascular field. This review will focus on the current knowledge regarding normal T-tubule structure and function in the heart, T-tubule remodelling in the transition from compensated hypertrophy to heart failure, and the impact of T-tubule remodelling on myocyte Ca(2+) handling function. In the last section, we discuss the molecular mechanisms underlying T-tubule remodelling in heart disease.
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Affiliation(s)
- Ang Guo
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
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22
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Toure A, Cabo C. Effect of heterogeneities in the cellular microstructure on propagation of the cardiac action potential. Med Biol Eng Comput 2012; 50:813-25. [PMID: 22729348 DOI: 10.1007/s11517-012-0934-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 06/05/2012] [Indexed: 10/28/2022]
Abstract
Cardiac arrhythmias are initiated in regions that undergo cellular remodeling as a result of disease. Using a sub-cellular model of myocardium, we studied the mechanism of block caused by tissue microstructure remodeling: cell geometry [quantified as length/width (L/W) cell ratio] and cell-to-cell coupling (G(j)). Heterogeneities in cell L/W ratio and G ( j ) lead to block when excitability is reduced and the corresponding space constant λ (in the direction of propagation) increases by >40 %. Tissue architectures with elongated cells (i.e. large cell L/W ratios) that are better coupled (i.e. large G(j)) are less prone to block at sites of regional heterogeneities in cell geometry and/or cell coupling than tissue architectures consisting of cells with smaller L/W ratios and/or poorer coupling. Whether an increase in tissue anisotropic ratio (ANR) is arrhythmogenic or not depends on the cellular mechanism of the increase: ANR leads to an increased risk of block when G(j) decreases, but to a decreased risk of block when cell L/W ratio increases. Our findings are useful to understand the mechanisms of block in cardiac pathologies that result in tissue architecture remodeling.
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Affiliation(s)
- Amadou Toure
- Department of Biomedical Engineering, City College of New York, City University of New York, New York, USA
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23
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Sachse FB, Torres NS, Savio-Galimberti E, Aiba T, Kass DA, Tomaselli GF, Bridge JH. Subcellular structures and function of myocytes impaired during heart failure are restored by cardiac resynchronization therapy. Circ Res 2012; 110:588-97. [PMID: 22253411 DOI: 10.1161/circresaha.111.257428] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
RATIONALE Cardiac resynchronization therapy (CRT) is an established treatment for patients with chronic heart failure. However, CRT-associated structural and functional remodeling at cellular and subcellular levels is only partly understood. OBJECTIVE To investigate the effects of CRT on subcellular structures and protein distributions associated with excitation-contraction coupling of ventricular cardiomyocytes. METHODS AND RESULTS Our studies revealed remodeling of the transverse tubular system (t-system) and the spatial association of ryanodine receptor (RyR) clusters in a canine model of dyssynchronous heart failure (DHF). We did not find this remodeling in a synchronous heart failure model based on atrial tachypacing. Remodeling in DHF ranged from minor alterations in anterior left ventricular myocytes to nearly complete loss of the t-system and dissociation of RyRs from sarcolemmal structures in lateral cells. After CRT, we found a remarkable and almost complete reverse remodeling of these structures despite persistent left ventricular dysfunction. Studies of whole-cell Ca(2+) transients showed that the structural remodeling and restoration were accompanied with remodeling and restoration of Ca(2+) signaling. CONCLUSIONS DHF is associated with regional remodeling of the t-system. Myocytes undergo substantial structural and functional restoration after only 3 weeks of CRT. The finding suggests that t-system status can provide an early marker of the success of this therapy. The results could also guide us to an understanding of the loss and remodeling of proteins associated with the t-system. The steep relationship between free Ca(2+) and contraction suggests that some restoration of Ca(2+) release units will have a disproportionately large effect on contractility.
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Affiliation(s)
- Frank B Sachse
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, 95 South 2000 East, Salt Lake City, UT 84112-5000, USA.
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24
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Lou Q, Janardhan A, Efimov IR. Remodeling of calcium handling in human heart failure. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:1145-74. [PMID: 22453987 PMCID: PMC3740791 DOI: 10.1007/978-94-007-2888-2_52] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Heart failure (HF) is an increasing public health problem accelerated by a rapidly aging global population. Despite considerable progress in managing the disease, the development of new therapies for effective treatment of HF remains a challenge. To identify targets for early diagnosis and therapeutic intervention, it is essential to understand the molecular and cellular basis of calcium handling and the signaling pathways governing the functional remodeling associated with HF in humans. Calcium (Ca(2+)) cycling is an essential mediator of cardiac contractile function, and remodeling of calcium handling is thought to be one of the major factors contributing to the mechanical and electrical dysfunction observed in HF. Active research in this field aims to bridge the gap between basic research and effective clinical treatments of HF. This chapter reviews the most relevant studies of calcium remodeling in failing human hearts and discusses their connections to current and emerging clinical therapies for HF patients.
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Affiliation(s)
- Qing Lou
- Department of Biomedical Engineering, Washington University in St. Louis, 390E Whitaker Hall, One Brookings Drive, St. Louis, MO 63130, USA
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25
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Abstract
The heart exhibits remarkable adaptive responses to a wide array of genetic and extrinsic factors to maintain contractile function. When compensatory responses are not sustainable, cardiac dysfunction occurs, leading to cardiomyopathy. The many forms of cardiomyopathy exhibit a set of overlapping phenotypes reflecting the limited range of compensatory responses that the heart can use. These include cardiac hypertrophy, induction of genes normally expressed during development, fibrotic deposits that replace necrotic and apoptotic cardiomyocytes, and metabolic disturbances. The compensatory responses are mediated by signaling pathways that initially serve to maintain normal contractility; however, persistent activation of these pathways leads to cardiac dysfunction. Current research focuses on ways to target these specific pathways therapeutically.
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Affiliation(s)
- Pamela A Harvey
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, USA
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26
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Balijepalli RC, Kamp TJ. Cardiomyocyte transverse tubule loss leads the way to heart failure. Future Cardiol 2011; 7:39-42. [PMID: 21174508 DOI: 10.2217/fca.10.113] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Evaluation of: Wei S, Guo A, Chen B et al.: T-tubule remodeling during transition from hypertrophy to heart failure. Circ. Res. 107(4), 520-531 (2010). The highly organized transverse (T)-tubule membrane system in ventricular myocytes plays an integral role in excitation-contraction coupling, and disruption of this T-tubule network has been implicated in contractile dysfunction in heart failure. Wei and colleagues used advanced confocal imaging techniques to evaluate cardiomyocyte membrane structure in intact rat hearts following surgically induced pressure overload, and demonstrated a loss of integrity of the T-tubule system. Importantly, this T-tubule dropout was detected early in the disease process, at the stage of compensated hypertrophy before observable ventricular dysfunction, and then progressed in proportion to the severity of the systolic dysfunction. These findings provide a new insight into the critical transition from compensated hypertrophy to heart failure and suggests important future areas for investigation.
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Affiliation(s)
- Ravi C Balijepalli
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
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27
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Crossman DJ, Ruygrok PR, Soeller C, Cannell MB. Changes in the organization of excitation-contraction coupling structures in failing human heart. PLoS One 2011; 6:e17901. [PMID: 21408028 PMCID: PMC3052389 DOI: 10.1371/journal.pone.0017901] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 02/14/2011] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The cardiac myocyte t-tubular system ensures rapid, uniform cell activation and several experimental lines of evidence suggest changes in the t-tubular system and associated excitation-contraction coupling proteins may occur in heart failure. METHODS AND RESULTS The organization of t-tubules, L-type calcium channels (DHPRs), ryanodine receptors (RyRs) and contractile machinery were examined in fixed ventricular tissue samples from both normal and failing hearts (idiopathic (non-ischemic) dilated cardiomyopathy) using high resolution fluorescent imaging. Wheat germ agglutinin (WGA), Na-Ca exchanger, DHPR and caveolin-3 labels revealed a shift from a predominantly transverse orientation to oblique and axial directions in failing myocytes. In failure, dilation of peripheral t-tubules occurred and a change in the extent of protein glycosylation was evident. There was no change in the fractional area occupied by myofilaments (labeled with phalloidin) but there was a small reduction in the number of RyR clusters per unit area. The general relationship between DHPRs and RyR was not changed and RyR labeling overlapped with 51±3% of DHPR labeling in normal hearts. In longitudinal (but not transverse) sections there was an ∼30% reduction in the degree of colocalization between DHPRs and RyRs as measured by Pearson's correlation coefficient in failing hearts. CONCLUSIONS The results show that extensive remodelling of the t-tubular network and associated excitation-contraction coupling proteins occurs in failing human heart. These changes may contribute to abnormal calcium handling in heart failure. The general organization of the t-system and changes observed in failure samples have subtle differences to some animal models although the general direction of changes are generally similar.
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Affiliation(s)
- David J. Crossman
- Department of Physiology, Faculty of Medicine and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Peter R. Ruygrok
- Department of Physiology, Faculty of Medicine and Health Sciences, University of Auckland, Auckland, New Zealand
- Auckland City Hospital, Auckland, New Zealand
| | - Christian Soeller
- Department of Physiology, Faculty of Medicine and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Mark B. Cannell
- Department of Physiology, Faculty of Medicine and Health Sciences, University of Auckland, Auckland, New Zealand
- * E-mail:
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van Oort RJ, Garbino A, Wang W, Dixit SS, Landstrom AP, Gaur N, De Almeida AC, Skapura DG, Rudy Y, Burns AR, Ackerman MJ, Wehrens XHT. Disrupted junctional membrane complexes and hyperactive ryanodine receptors after acute junctophilin knockdown in mice. Circulation 2011; 123:979-88. [PMID: 21339484 DOI: 10.1161/circulationaha.110.006437] [Citation(s) in RCA: 207] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Excitation-contraction coupling in striated muscle requires proper communication of plasmalemmal voltage-activated Ca2+ channels and Ca2+ release channels on sarcoplasmic reticulum within junctional membrane complexes. Although previous studies revealed a loss of junctional membrane complexes and embryonic lethality in germ-line junctophilin-2 (JPH2) knockout mice, it has remained unclear whether JPH2 plays an essential role in junctional membrane complex formation and the Ca(2+)-induced Ca(2+) release process in the heart. Our recent work demonstrated loss-of-function mutations in JPH2 in patients with hypertrophic cardiomyopathy. METHODS AND RESULTS To elucidate the role of JPH2 in the heart, we developed a novel approach to conditionally reduce JPH2 protein levels using RNA interference. Cardiac-specific JPH2 knockdown resulted in impaired cardiac contractility, which caused heart failure and increased mortality. JPH2 deficiency resulted in loss of excitation-contraction coupling gain, precipitated by a reduction in the number of junctional membrane complexes and increased variability in the plasmalemma-sarcoplasmic reticulum distance. CONCLUSIONS Loss of JPH2 had profound effects on Ca2+ release channel inactivation, suggesting a novel functional role for JPH2 in regulating intracellular Ca2+ release channels in cardiac myocytes. Thus, our novel approach of cardiac-specific short hairpin RNA-mediated knockdown of junctophilin-2 has uncovered a critical role for junctophilin in intracellular Ca2+ release in the heart.
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Affiliation(s)
- Ralph J van Oort
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, One Baylor Plaza, BCM335, Houston, TX 77030, USA
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Heinzel FR, MacQuaide N, Biesmans L, Sipido K. Dyssynchrony of Ca2+ release from the sarcoplasmic reticulum as subcellular mechanism of cardiac contractile dysfunction. J Mol Cell Cardiol 2010; 50:390-400. [PMID: 21075114 DOI: 10.1016/j.yjmcc.2010.11.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 09/30/2010] [Accepted: 11/05/2010] [Indexed: 02/05/2023]
Abstract
Cardiac contractile function depends on coordinated electrical activation throughout the heart. Dyssynchronous electrical activation of the ventricles has been shown to contribute to contractile dysfunction in heart failure, and resynchronization therapy has emerged as a therapeutic concept. At the cellular level, coupling of membrane excitation to myofilament contraction is facilitated by highly organized intracellular structures which coordinate Ca(2+) release. The cytosolic [Ca(2+)] transient triggered by depolarization-induced Ca(2+) influx is the result of a gradable and robust high gain process, Ca(2+)-induced Ca(2+) release (CICR), which integrates subcellular localized Ca(2+) release events. Lack of synchronization of these localized release events can contribute to contractile dysfunction in myocardial hypertrophy and heart failure. Different underlying mechanisms relate to functional and structural changes in sarcolemmal Ca(2+) channels, the sarcoplasmic Ca(2+) release channel or ryanodine receptor, RyR, their intracellular arrangement in close proximity in couplons and the loss of t-tubules. Dyssynchrony at the subcellular level translates in a reduction of the overall gain of CICR at the cellular level and forms an important determinant of myocyte contractility in heart failure.
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