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Sridhar S, Clayton RH. Fibroblast mediated dynamics in diffusively uncoupled myocytes: a simulation study using 2-cell motifs. Sci Rep 2024; 14:4493. [PMID: 38396245 PMCID: PMC10891142 DOI: 10.1038/s41598-024-54564-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 02/14/2024] [Indexed: 02/25/2024] Open
Abstract
In healthy hearts myocytes are typically coupled to nearest neighbours through gap junctions. Under pathological conditions such as fibrosis, or in scar tissue, or across ablation lines myocytes can uncouple from their neighbours. Electrical conduction may still occur via fibroblasts that not only couple proximal myocytes but can also couple otherwise unconnected regions. We hypothesise that such coupling can alter conduction between myocytes via introduction of delays or by initiation of premature stimuli that can potentially result in reentry or conduction blocks. To test this hypothesis we have developed several 2-cell motifs and investigated the effect of fibroblast mediated electrical coupling between uncoupled myocytes. We have identified various regimes of myocyte behaviour that depend on the strength of gap-junctional conductance, connection topology, and parameters of the myocyte and fibroblast models. These motifs are useful in developing a mechanistic understanding of long-distance coupling on myocyte dynamics and enable the characterisation of interaction between different features such as myocyte and fibroblast properties, coupling strengths and pacing period. They are computationally inexpensive and allow for incorporation of spatial effects such as conduction velocity. They provide a framework for constructing scar tissue boundaries and enable linking of cellular level interactions with scar induced arrhythmia.
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Affiliation(s)
- S Sridhar
- Department of Computer Science, University of Sheffield, Sheffield, UK.
| | - Richard H Clayton
- Department of Computer Science, University of Sheffield, Sheffield, UK
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2
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Simon-Chica A, Wülfers EM, Kohl P. Nonmyocytes as electrophysiological contributors to cardiac excitation and conduction. Am J Physiol Heart Circ Physiol 2023; 325:H475-H491. [PMID: 37417876 PMCID: PMC10538996 DOI: 10.1152/ajpheart.00184.2023] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/22/2023] [Accepted: 06/29/2023] [Indexed: 07/08/2023]
Abstract
Although cardiac action potential (AP) generation and propagation have traditionally been attributed exclusively to cardiomyocytes (CM), other cell types in the heart are also capable of forming electrically conducting junctions. Interactions between CM and nonmyocytes (NM) enable and modulate each other's activity. This review provides an overview of the current understanding of heterocellular electrical communication in the heart. Although cardiac fibroblasts were initially thought to be electrical insulators, recent studies have demonstrated that they form functional electrical connections with CM in situ. Other NM, such as macrophages, have also been recognized as contributing to cardiac electrophysiology and arrhythmogenesis. Novel experimental tools have enabled the investigation of cell-specific activity patterns in native cardiac tissue, which is expected to yield exciting new insights into the development of novel or improved diagnostic and therapeutic strategies.
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Affiliation(s)
- Ana Simon-Chica
- Novel Arrhythmogenic Mechanisms Program, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Eike M Wülfers
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Department of Physics and Astronomy, Faculty of Sciences, Ghent University, Gent, Belgium
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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3
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Brocklehurst P, Zhang H, Ye J. Effects of fibroblast on electromechanical dynamics of human atrial tissue—insights from a 2D discrete element model. Front Physiol 2022; 13:938497. [PMID: 35957981 PMCID: PMC9360525 DOI: 10.3389/fphys.2022.938497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Accepted: 07/04/2022] [Indexed: 11/13/2022] Open
Abstract
Roughly 75% of normal myocardial tissue volume is comprised of myocytes, however, fibroblasts by number are the most predominant cells in cardiac tissue. Previous studies have shown distinctive differences in cellular electrophysiology and excitability between myocytes and fibroblasts. However, it is still unclear how the electrical coupling between the two and the increased population of fibroblasts affects the electromechanical dynamics of cardiac tissue. This paper focuses on investigating effects of fibroblast-myocyte electrical coupling (FMEC) and fibroblast population on atrial electrical conduction and mechanical contractility by using a two-dimensional Discrete Element Method (DEM) model of cardiac tissue that is different to finite element method (FEM). In the model, the electro-mechanics of atrial cells are modelled by a biophysically detailed model for atrial electrical action potentials and myofilament kinetics, and the atrial fibroblasts are modelled by an active model that considers four active membrane ionic channel currents. Our simulation results show that the FMEC impairs myocytes’ electrical action potential and mechanical contractibility, manifested by reduced upstroke velocity, amplitude and duration of action potentials, as well as cell length shortening. At the tissue level, the FMEC slows down the conduction of excitation waves, and reduces strain of the tissue produced during a contraction course. These findings provide new insights into understandings of how FMEC impairs cardiac electrical and mechanical dynamics of the heart.
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Affiliation(s)
- Paul Brocklehurst
- Engineering Department, Lancaster University, Lancaster, United Kingdom
| | - Henggui Zhang
- Biological Physics Group, School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom
- *Correspondence: Henggui Zhang, ; Jianqiao Ye,
| | - Jianqiao Ye
- Engineering Department, Lancaster University, Lancaster, United Kingdom
- *Correspondence: Henggui Zhang, ; Jianqiao Ye,
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4
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Liu F, Wu H, Yang X, Dong Y, Huang G, Genin GM, Lu TJ, Xu F. A new model of myofibroblast-cardiomyocyte interactions and their differences across species. Biophys J 2021; 120:3764-3775. [PMID: 34280368 DOI: 10.1016/j.bpj.2021.06.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 06/02/2021] [Accepted: 06/28/2021] [Indexed: 11/18/2022] Open
Abstract
Although coupling between cardiomyocytes and myofibroblasts is well known to affect the physiology and pathophysiology of cardiac tissues across species, relating these observations to humans is challenging because the effect of this coupling varies across species and because the sources of these effects are not known. To identify the sources of cross-species variation, we built upon previous mathematical models of myofibroblast electrophysiology and developed a mechanoelectrical model of cardiomyocyte-myofibroblast interactions as mediated by electrotonic coupling and transforming growth factor-β1. The model, as verified by experimental data from the literature, predicted that both electrotonic coupling and transforming growth factor-β1 interaction between myocytes and myofibroblast prolonged action potential in rat myocytes but shortened action potential in human myocytes. This variance could be explained by differences in the transient outward K+ current associated with differential Kv4.2 gene expression across species. Results are useful for efforts to extrapolate the results of animal models to the predicted effects in humans and point to potential therapeutic targets for fibrotic cardiomyopathy.
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Affiliation(s)
- Fusheng Liu
- State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an, P.R. China; Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an, P.R. China; Bioinspired Engineering and Biomechanics Center, Xi'an Jiaotong University, Xi'an, P.R. China
| | - Hou Wu
- State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an, P.R. China; Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an, P.R. China
| | - Xiaoyu Yang
- State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi'an, P.R. China; Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an, P.R. China
| | - Yuqin Dong
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an, P.R. China; Bioinspired Engineering and Biomechanics Center, Xi'an Jiaotong University, Xi'an, P.R. China
| | - Guoyou Huang
- Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan, P.R. China
| | - Guy M Genin
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an, P.R. China; Bioinspired Engineering and Biomechanics Center, Xi'an Jiaotong University, Xi'an, P.R. China; Department of Mechanical Engineering & Materials Science, St. Louis, Missouri; NSF Science and Technology Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, Missouri
| | - Tian Jian Lu
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing, P.R. China.
| | - Feng Xu
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an, P.R. China; Bioinspired Engineering and Biomechanics Center, Xi'an Jiaotong University, Xi'an, P.R. China.
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5
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Bragard J, Witt A, Laroze D, Hawks C, Elorza J, Rodríguez Cantalapiedra I, Peñaranda A, Echebarria B. Conductance heterogeneities induced by multistability in the dynamics of coupled cardiac gap junctions. CHAOS (WOODBURY, N.Y.) 2021; 31:073144. [PMID: 34340360 DOI: 10.1063/5.0053651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/08/2021] [Indexed: 06/13/2023]
Abstract
In this paper, we study the propagation of the cardiac action potential in a one-dimensional fiber, where cells are electrically coupled through gap junctions (GJs). We consider gap junctional gate dynamics that depend on the intercellular potential. We find that different GJs in the tissue can end up in two different states: a low conducting state and a high conducting state. We first present evidence of the dynamical multistability that occurs by setting specific parameters of the GJ dynamics. Subsequently, we explain how the multistability is a direct consequence of the GJ stability problem by reducing the dynamical system's dimensions. The conductance dispersion usually occurs on a large time scale, i.e., thousands of heartbeats. The full cardiac model simulations are computationally demanding, and we derive a simplified model that allows for a reduction in the computational cost of four orders of magnitude. This simplified model reproduces nearly quantitatively the results provided by the original full model. We explain the discrepancies between the two models due to the simplified model's lack of spatial correlations. This simplified model provides a valuable tool to explore cardiac dynamics over very long time scales. That is highly relevant in studying diseases that develop on a large time scale compared to the basic heartbeat. As in the brain, plasticity and tissue remodeling are crucial parameters in determining the action potential wave propagation's stability.
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Affiliation(s)
- J Bragard
- Departamento de Física y Matemática Aplicada, Universidad de Navarra, Pamplona 31080, Spain
| | - A Witt
- Max-Planck Institute, Gottingen 37077, Germany
| | - D Laroze
- Instituto de Alta Investigación, CEDENNA, Universidad de Tarapacá, Casilla 7D, Arica, Chile
| | - C Hawks
- Departamento de Física y Matemática Aplicada, Universidad de Navarra, Pamplona 31080, Spain
| | - J Elorza
- Departamento de Física y Matemática Aplicada, Universidad de Navarra, Pamplona 31080, Spain
| | | | - A Peñaranda
- Departament de Física, Universitat Politècnica de Catalunya, Barcelona 08068, Spain
| | - B Echebarria
- Departament de Física, Universitat Politècnica de Catalunya, Barcelona 08068, Spain
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6
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Jiang X, Cheng H, Huang J, Cui C, Zhu Y, Lin Y, Miao W, Liu H, Chen H, Ju W, Chen M. Construction of chamber-specific engineered cardiac tissues in vitro with human iPSC-derived cardiomyocytes and human foreskin fibroblasts. J Biosci Bioeng 2021; 132:198-205. [PMID: 34074596 DOI: 10.1016/j.jbiosc.2021.04.012] [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] [Received: 02/09/2021] [Revised: 04/12/2021] [Accepted: 04/26/2021] [Indexed: 11/19/2022]
Abstract
Human-induced pluripotent stem cell (hiPSC) technology and directed cardiac differentiation technology can provide a continuous supply of cells for disease modeling, drug screening, and cell therapy. However, two-dimensional (2D) cells often fail to faithfully reflect the physiological structure and function of the heart. Considering the contractile function is the most critical and easy-to-understand function of cardiomyocytes, the engineered cardiac tissues (ECT) with mechanical properties may serve as an appropriate three-dimensional (3D) platform for drug evaluation. At present, there are various methods to generate ECTs, some of which are quite costly. In the present study, we proposed that human foreskin fibroblast (HFF) cells, as a cost-effective and accessible cell source, can promote the compaction and remodeling of ECTs. The HFFs derived ECTs displayed stable structural and functional characteristics with a higher performance-to-price ratio. Moreover, both ECTs made from atrial and ventricular cardiomyocytes showed an excellent drug response, demonstrating that the ECT with HFFs as an easy and reliable platform for drug evaluation.
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Affiliation(s)
- Xiaohong Jiang
- Division of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Hongyi Cheng
- Division of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Jiayi Huang
- Division of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Chang Cui
- Division of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Yue Zhu
- Division of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Yongping Lin
- Division of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Weilun Miao
- Division of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Hailei Liu
- Division of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Hongwu Chen
- Division of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Weizhu Ju
- Division of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
| | - Minglong Chen
- Division of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
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7
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Simon-Chica A, Fernández MC, Wülfers EM, Lother A, Hilgendorf I, Seemann G, Ravens U, Kohl P, Schneider-Warme F. Novel insights into the electrophysiology of murine cardiac macrophages: relevance of voltage-gated potassium channels. Cardiovasc Res 2021; 118:798-813. [PMID: 33823533 PMCID: PMC8859634 DOI: 10.1093/cvr/cvab126] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 04/05/2021] [Indexed: 12/24/2022] Open
Abstract
AIMS Macrophages (MΦ), known for immunological roles such as phagocytosis and antigen presentation, have been found to electrotonically couple to cardiomyocytes (CM) of the atrio-ventricular node via Cx43, affecting cardiac conduction in isolated mouse hearts. Here, we characterise passive and active electrophysiological properties of murine cardiac resident MΦ, and model their potential electrophysiological relevance for CM. METHODS AND RESULTS We combined classic electrophysiological approaches with 3 D florescence imaging, RNA-sequencing, pharmacological interventions and computer simulations. We used Cx3cr1eYFP/+ mice wherein cardiac MΦ were fluorescently labelled. FACS-purified fluorescent MΦ from mouse hearts were studied by whole-cell patch-clamp. MΦ electrophysiological properties include: membrane resistance 2.2 ± 0.1 GΩ (all data mean±SEM), capacitance 18.3 ± 0.1 pF, resting membrane potential -39.6 ± 0.3 mV, and several voltage-activated, outward or inwardly-rectifying potassium currents. Using ion channel blockers (barium, TEA, 4-AP, margatoxin, XEN-D0103, DIDS), flow cytometry, immuno-staining and RNA-sequencing, we identified Kv1.3, Kv1.5 and Kir2.1 as channels contributing to observed ion currents. MΦ displayed four patterns for outward and two for inward-rectifier potassium currents. Additionally, MΦ showed surface expression of Cx43, a prerequisite for homo- and/or heterotypic electrotonic coupling. Experimental results fed into development of an original computational model to describe cardiac MΦ electrophysiology. Computer simulations to quantitatively assess plausible effects of MΦ on electrotonically coupled CM showed that MΦ can depolarise resting CM, shorten early and prolong late action potential duration, with effects depending on coupling strength and individual MΦ electrophysiological properties, in particular resting membrane potential and presence/absence of Kir2.1. CONCLUSIONS Our results provide a first electrophysiological characterisation of cardiac resident MΦ, and a computational model to quantitatively explore their relevance in the heterocellular heart. Future work will be focussed at distinguishing electrophysiological effects of MΦ-CM coupling on both cell types during steady-state and in patho-physiological remodelling, when immune cells change their phenotype, proliferate, and/or invade from external sources. TRANSLATIONAL PERSPECTIVE Cardiac tissue contains resident macrophages (MΦ) which, beyond immunological and housekeeping roles, have been found to electrotonically couple via connexins to cardiomyocytes (CM), stabilising atrio-ventricular conduction at high excitation rates. Here, we characterise structure and electrophysiological function of murine cardiac MΦ and provide a computational model to quantitatively probe the potential relevance of MΦ-CM coupling for cardiac electrophysiology. We find that MΦ are unlikely to have major electrophysiological effects in normal tissue, where they would hasten early and slow late CM-repolarisation. Further work will address potential arrhythmogenicity of MΦ in patho-physiologically remodelled tissue containing elevated MΦ-numbers, incl. non-resident recruited cells.
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Affiliation(s)
- Ana Simon-Chica
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg · Bad Krozingen, Medical Center-University of Freiburg and Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Spanish National Cardiovascular Research Center, Carlos III (CNIC), Myocardial Pathophysiology Area, Madrid, Spain
| | - Marbely C Fernández
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg · Bad Krozingen, Medical Center-University of Freiburg and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Eike M Wülfers
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg · Bad Krozingen, Medical Center-University of Freiburg and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Achim Lother
- Department of Cardiology and Angiology I, University Heart Center Freiburg · Bad Krozingen, Medical Center-University of Freiburg and Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ingo Hilgendorf
- Department of Cardiology and Angiology I, University Heart Center Freiburg · Bad Krozingen, Medical Center-University of Freiburg and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Gunnar Seemann
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg · Bad Krozingen, Medical Center-University of Freiburg and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ursula Ravens
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg · Bad Krozingen, Medical Center-University of Freiburg and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg · Bad Krozingen, Medical Center-University of Freiburg and Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Franziska Schneider-Warme
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg · Bad Krozingen, Medical Center-University of Freiburg and Faculty of Medicine, University of Freiburg, Freiburg, Germany
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8
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Kostecki GM, Shi Y, Chen CS, Reich DH, Entcheva E, Tung L. Optogenetic current in myofibroblasts acutely alters electrophysiology and conduction of co-cultured cardiomyocytes. Sci Rep 2021; 11:4430. [PMID: 33627695 PMCID: PMC7904933 DOI: 10.1038/s41598-021-83398-4] [Citation(s) in RCA: 10] [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: 10/25/2020] [Accepted: 01/27/2021] [Indexed: 01/31/2023] Open
Abstract
Interactions between cardiac myofibroblasts and myocytes may slow conduction and generate spontaneous beating in fibrosis, increasing the chance of life-threatening arrhythmia. While co-culture studies have shown that myofibroblasts can affect cardiomyocyte electrophysiology in vitro, the extent of myofibroblast-myocyte electrical conductance in a syncytium is unknown. In this neonatal rat study, cardiac myofibroblasts were transduced with Channelrhodopsin-2, which allowed acute and selective increase of myofibroblast current, and plated on top of cardiomyocytes. Optical mapping revealed significantly decreased conduction velocity (- 27 ± 6%, p < 10-3), upstroke rate (- 13 ± 4%, p = 0.002), and action potential duration (- 14 ± 7%, p = 0.004) in co-cultures when 0.017 mW/mm2 light was applied, as well as focal spontaneous beating in 6/7 samples and a decreased cycle length (- 36 ± 18%, p = 0.002) at 0.057 mW/mm2 light. In silico modeling of the experiments reproduced the experimental findings and suggested the light levels used in experiments produced excess current similar in magnitude to endogenous myofibroblast current. Fitting the model to experimental data predicted a tissue-level electrical conductance across the 3-D interface between myofibroblasts and cardiomyocytes of ~ 5 nS/cardiomyocyte, and showed how increased myofibroblast-myocyte conductance, increased myofibroblast/myocyte capacitance ratio, and increased myofibroblast current, which occur in fibrosis, can work in tandem to produce pro-arrhythmic increases in conduction and spontaneous beating.
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Affiliation(s)
- Geran M Kostecki
- Department of Biomedical Engineering, Johns Hopkins University, 720 Rutland Ave., Baltimore, MD, 21205, USA
| | - Yu Shi
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Christopher S Chen
- Biological Design Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
| | - Daniel H Reich
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Emilia Entcheva
- Department of Biomedical Engineering, George Washington University, Washington, DC, USA
| | - Leslie Tung
- Department of Biomedical Engineering, Johns Hopkins University, 720 Rutland Ave., Baltimore, MD, 21205, USA.
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9
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Bazhutina A, Balakina-Vikulova NA, Kursanov A, Solovyova O, Panfilov A, Katsnelson LB. Mathematical modelling of the mechano-electric coupling in the human cardiomyocyte electrically connected with fibroblasts. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 159:46-57. [PMID: 32846154 DOI: 10.1016/j.pbiomolbio.2020.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 08/11/2020] [Accepted: 08/14/2020] [Indexed: 01/12/2023]
Abstract
Cardiac fibroblasts are interspersed within mammalian cardiac tissue. Fibroblasts are mechanically passive; however, they may communicate electrically with cardiomyocytes via gap junctions and thus affect the electrical and mechanical activity of myocytes. Several in-silico studies at both cellular (0D) and ventricular (3D) levels analysed the effects of fibroblasts on the myocardial electrical function. However, none of them addressed possible effects of fibroblast-myocyte electrical coupling to cardiomyocyte mechanical activity. In this paper, we propose a mathematical model for studying both electrical and mechanical responses of the human cardiomyocyte to its electrotonic interaction with cardiac fibroblasts. Our simulations have revealed that electrotonic interaction with fibroblasts affects not only the mechanical activity of the cardiomyocyte, comprising either moderate or significant reduction of contractility, but also the mechano-calcium and mechano-electric feedback loops, and all these effects are enhanced as the number of coupled fibroblasts is increased. Obtained results suggest that moderate values of the myocyte-fibroblast gap junction conductance (less than 1 nS) can be attributed to physiological conditions, contrasting to the higher values (2 nS and higher) proper rather for pathological situations (e.g. for infarct and/or border zones), since all mechanical indexes falls down dramatically in the case of such high conductance.
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Affiliation(s)
| | - Nathalie A Balakina-Vikulova
- Ural Federal University, Ekaterinburg, Russia; Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
| | - Alexander Kursanov
- Ural Federal University, Ekaterinburg, Russia; Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
| | - Olga Solovyova
- Ural Federal University, Ekaterinburg, Russia; Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia
| | - Alexander Panfilov
- Ural Federal University, Ekaterinburg, Russia; Ghent University, Ghent, Belgium
| | - Leonid B Katsnelson
- Ural Federal University, Ekaterinburg, Russia; Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia.
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10
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Zhao Y, Rafatian N, Wang EY, Feric NT, Lai BFL, Knee-Walden EJ, Backx PH, Radisic M. Engineering microenvironment for human cardiac tissue assembly in heart-on-a-chip platform. Matrix Biol 2020; 85-86:189-204. [PMID: 30981898 PMCID: PMC6788963 DOI: 10.1016/j.matbio.2019.04.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 04/08/2019] [Accepted: 04/09/2019] [Indexed: 12/19/2022]
Abstract
Organ-on-a-chip systems have the potential to revolutionize drug screening and disease modeling through the use of human stem cell-derived cardiomyocytes. The predictive power of these tissue models critically depends on the functional assembly and maturation of human cells that are used as building blocks for organ-on-a-chip systems. To resemble a more adult-like phenotype on these heart-on-a-chip systems, the surrounding micro-environment of individual cardiomyocyte needs to be controlled. Herein, we investigated the impact of four microenvironmental cues: cell seeding density, types and percentages of non-myocyte populations, the types of hydrogels used for tissue inoculation and the electrical conditioning regimes on the structural and functional assembly of human pluripotent stem cell-derived cardiac tissues. Utilizing a novel, plastic and open-access heart-on-a-chip system that is capable of continuous non-invasive monitoring of tissue contractions, we were able to study how different micro-environmental cues affect the assembly of the cardiomyocytes into a functional cardiac tissue. We have defined conditions that resulted in tissues exhibiting hallmarks of the mature human myocardium, such as positive force-frequency relationship and post-rest potentiation.
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Affiliation(s)
- Yimu Zhao
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5; Canada
| | - Naimeh Rafatian
- Division of Cardiology and Peter Munk Cardiac Center, University of Health Network, Toronto, Ontario M5G 2N2, Canada
| | - Erika Y Wang
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9, Canada
| | - Nicole T Feric
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9, Canada; TARA Biosystems, Inc., New York, NY 10016, USA
| | - Benjamin F L Lai
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9, Canada
| | - Ericka J Knee-Walden
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9, Canada
| | - Peter H Backx
- Division of Cardiology and Peter Munk Cardiac Center, University of Health Network, Toronto, Ontario M5G 2N2, Canada; Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada; Toronto General Research Institute, Toronto, Ontario M5G 2C4; Canada
| | - Milica Radisic
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5; Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9, Canada; Toronto General Research Institute, Toronto, Ontario M5G 2C4; Canada.
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11
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Biendarra-Tiegs SM, Clemens DJ, Secreto FJ, Nelson TJ. Human Induced Pluripotent Stem Cell-Derived Non-Cardiomyocytes Modulate Cardiac Electrophysiological Maturation Through Connexin 43-Mediated Cell-Cell Interactions. Stem Cells Dev 2019; 29:75-89. [PMID: 31744402 PMCID: PMC6978788 DOI: 10.1089/scd.2019.0098] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The functional maturation status of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) has a notable impact upon their use in pharmacological studies, disease modeling, and therapeutic applications. Non-cardiomyocytes (non-CMs) produced in the differentiation process have previously been identified as having an extrinsic influence upon hiPSC-CM development, yet the underlying mechanisms are not fully understood. Herein, we aimed to modulate electrophysiological properties of hiPSC-CMs within co-cultures containing varied proportions of non-CMs and investigate the nature of interactions between these different cell types. Therefore, we sorted cardiac differentiations on day 10 and subsequently replated the cells at ratios of 7:3, 1:1, 3:7, and 1:9 non-CMs to CMs. After a month of co-culture, we evaluated electrophysiological properties through the genetically encoded voltage indicator ArcLight. We ultimately identified that co-cultures with approximately 70%–90% CM purity demonstrated the highest action potential (AP) amplitude and maximum upstroke velocity by day 40 of differentiation, indicative of enhanced electrophysiological maturation, as well as more ventricular-like AP morphologies. Notably, these findings were distinct from those observed for co-cultures of hiPSC-CMs and dermal fibroblasts. We determined that the co-culture phenotypes could not be attributed to paracrine effects of non-CMs due to the inability of conditioned media to recapitulate the observed effects. This led to the further observation of a distinctive expression pattern of connexin 43 (Cx43) at cell-cell interfaces between both CMs and non-CMs. Depletion of Cx43 by short hairpin RNA (shRNA) specifically in the non-CM population within a co-culture environment was able to recapitulate electrophysiological phenotypes of a purer hiPSC-CM population. Collectively, our data demonstrate that abundant non-CM content exerts a significant negative influence upon the electrophysiological maturation of hiPSC-CMs through Cx43-mediated cell-cell-contacts, and thus should be considered regarding the future production of purpose-built hiPSC-CM systems.
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Affiliation(s)
- Sherri M Biendarra-Tiegs
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Center for Regenerative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Daniel J Clemens
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota
| | - Frank J Secreto
- Center for Regenerative Medicine, Mayo Clinic, Rochester, Minnesota.,Division of General Internal Medicine, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota
| | - Timothy J Nelson
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Center for Regenerative Medicine, Mayo Clinic, Rochester, Minnesota.,Division of General Internal Medicine, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota.,Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
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12
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Soucy JR, Askaryan J, Diaz D, Koppes AN, Annabi N, Koppes RA. Glial cells influence cardiac permittivity as evidenced through in vitro and in silico models. Biofabrication 2019; 12:015014. [PMID: 31593932 PMCID: PMC11062241 DOI: 10.1088/1758-5090/ab4c0a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Excitation-contraction (EC) coupling in the heart has, until recently, been solely accredited to cardiomyocytes. The inherent complexities of the heart make it difficult to examine non-muscle contributions to contraction in vivo, and conventional in vitro models fail to capture multiple features and cellular heterogeneity of the myocardium. Here, we report on the development of a 3D cardiac μTissue to investigate changes in the cellular composition of native myocardium in vitro. Cells are encapsulated within micropatterned gelatin-based hydrogels formed via visible light photocrosslinking. This system enables spatial control of the microarchitecture, perturbation of the cellular composition, and functional measures of EC coupling via video microscopy and a custom algorithm to quantify beat frequency and degree of coordination. To demonstrate the robustness of these tools and evaluate the impact of altered cell population densities on cardiac μTissues, contractility and cell morphology were assessed with the inclusion of exogenous non-myelinating Schwann cells (SCs). Results demonstrate that the addition of exogenous SCs alter cardiomyocyte EC, profoundly inhibiting the response to electrical pacing. Computational modeling of connexin-mediated coupling suggests that SCs impact cardiomyocyte resting potential and rectification following depolarization. Cardiac μTissues hold potential for examining the role of cellular heterogeneity in heart health, pathologies, and cellular therapies.
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Affiliation(s)
- Jonathan R Soucy
- Department of Chemical Engineering, Northeastern University, Boston, MA 02115, United States of America
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13
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Liang C, Wang K, Li Q, Bai J, Zhang H. Influence of the distribution of fibrosis within an area of myocardial infarction on wave propagation in ventricular tissue. Sci Rep 2019; 9:14151. [PMID: 31578428 PMCID: PMC6775234 DOI: 10.1038/s41598-019-50478-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 09/13/2019] [Indexed: 12/22/2022] Open
Abstract
The presence of fibrosis in heart tissue is strongly correlated with an incidence of arrhythmia, which is a leading cause of sudden cardiac death (SCD). However, it remains incompletely understood how different distributions, sizes and positions of fibrotic tissues contribute to arrhythmogenesis. In this study, we designed 4 different ventricular models mimicking wave propagation in cardiac tissues under normal, myocardial infarction (MI), MI with random fibrosis and MI with gradient fibrosis conditions. Simulation results of ideal square tissues indicate that vulnerable windows (VWs) of random and gradient fibrosis distributions are similar with low levels of fibrosis. However, with a high level of fibrosis, the VWs significantly increase in random fibrosis tissue but not in gradient fibrosis tissue. In addition, we systematically analyzed the effects of the size and position of fibrosis tissues on VWs. Simulation results show that it is more likely for a reentry wave to appear when the length of the infarcted area is greater than 25% of the perimeter of the ventricle, when the width is approximately half that of the ventricular wall, or when the infarcted area is attached to the inside or outside of the ventricular wall.
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Affiliation(s)
- Cuiping Liang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China
| | - Kuanquan Wang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China.
| | - Qince Li
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China.
| | - Jieyun Bai
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China
| | - Henggui Zhang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China.,School of Physics and Astronomy, The University of Manchester, Manchester, UK.,Space Institute of Southern China, Shenzhen, China.,Key Laboratory of Medical Electrophysiology, Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease/Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
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14
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Sánchez J, Gomez JF, Martinez-Mateu L, Romero L, Saiz J, Trenor B. Heterogeneous Effects of Fibroblast-Myocyte Coupling in Different Regions of the Human Atria Under Conditions of Atrial Fibrillation. Front Physiol 2019; 10:847. [PMID: 31333496 PMCID: PMC6620707 DOI: 10.3389/fphys.2019.00847] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 06/19/2019] [Indexed: 12/19/2022] Open
Abstract
Background: Atrial fibrillation (AF), the most common cardiac arrhythmia, is characterized by alteration of the action potential (AP) propagation. Under persistent AF, myocytes undergo electrophysiological and structural remodeling, which involves fibroblast proliferation and differentiation, modifying the substrate for AP propagation. The aim of this study was to analyze the effects on the AP of fibroblast-myocyte coupling during AF and its propagation in different regions of the atria. Methods: Isolated myocytes were coupled to different numbers of fibroblasts using the established AP models and tissue simulations were performed by randomly distributing fibroblasts. Fibroblast formulations were updated to match recent experimental data. Major ion current conductances of the myocyte model were modified to simulate AP heterogeneity in four different atrial regions (right atrium posterior wall, crista terminalis, left atrium posterior wall, and pulmonary vein) according to experimental and computational studies. Results: The results of the coupled myocyte-fibroblast simulations suggest that a more depolarized membrane potential and higher fibroblast membrane capacitance have a greater impact on AP duration and myocyte maximum depolarization velocity. The number of coupled fibroblasts and the stimulation frequency are determining factors in altering myocyte AP. Strand simulations show that conduction velocity tends to homogenize in all regions, while the left atrium is more likely to be affected by fibroblast and AP propagation block is more likely to occur. The pulmonary vein is the most affected region, even at low fibroblast densities. In 2D sheets with randomly placed fibroblasts, wavebreaks are observed in the low density (10%) central fibrotic zone and when fibroblast density increases (40%) propagation in the fibrotic region is practically blocked. At densities of 10 and 20% the width of the vulnerable window increases with respect to control but is decreased at 40%. Conclusion: Myocyte-fibroblast coupling characteristics heterogeneously affect AP propagation and features in the different atrial zones, and myocytes from the left atria are more sensitive to fibroblast coupling.
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Affiliation(s)
- Jorge Sánchez
- Centre for Research and Innovation in Bioengineering, Universitat Politècnica de València, Valencia, Spain
| | - Juan F Gomez
- Centre for Research and Innovation in Bioengineering, Universitat Politècnica de València, Valencia, Spain
| | - Laura Martinez-Mateu
- Centre for Research and Innovation in Bioengineering, Universitat Politècnica de València, Valencia, Spain
| | - Lucia Romero
- Centre for Research and Innovation in Bioengineering, Universitat Politècnica de València, Valencia, Spain
| | - Javier Saiz
- Centre for Research and Innovation in Bioengineering, Universitat Politècnica de València, Valencia, Spain
| | - Beatriz Trenor
- Centre for Research and Innovation in Bioengineering, Universitat Politècnica de València, Valencia, Spain
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15
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Bragard J, Sankarankutty AC, Sachse FB. Extended Bidomain Modeling of Defibrillation: Quantifying Virtual Electrode Strengths in Fibrotic Myocardium. Front Physiol 2019; 10:337. [PMID: 31001135 PMCID: PMC6456788 DOI: 10.3389/fphys.2019.00337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 03/13/2019] [Indexed: 11/17/2022] Open
Abstract
Defibrillation is a well-established therapy for atrial and ventricular arrhythmia. Here, we shed light on defibrillation in the fibrotic heart. Using the extended bidomain model of electrical conduction in cardiac tissue, we assessed the influence of fibrosis on the strength of virtual electrodes caused by extracellular electrical current. We created one-dimensional models of rabbit ventricular tissue with a central patch of fibrosis. The fibrosis was incorporated by altering volume fractions for extracellular, myocyte and fibroblast domains. In our prior work, we calculated these volume fractions from microscopic images at the infarct border zone of rabbit hearts. An average and a large degree of fibrosis were modeled. We simulated defibrillation by application of an extracellular current for a short duration (5 ms). We explored the effects of myocyte-fibroblast coupling, intra-fibroblast conductivity and patch length on the strength of the virtual electrodes present at the borders of the normal and fibrotic tissue. We discriminated between effects on myocyte and fibroblast membranes at both borders of the patch. Similarly, we studied defibrillation in two-dimensional models of fibrotic tissue. Square and disk-like patches of fibrotic tissue were embedded in control tissue. We quantified the influence of the geometry and fibrosis composition on virtual electrode strength. We compared the results obtained with a square and disk shape of the fibrotic patch with results from the one-dimensional simulations. Both, one- and two-dimensional simulations indicate that extracellular current application causes virtual electrodes at boundaries of fibrotic patches. A higher degree of fibrosis and larger patch size were associated with an increased strength of the virtual electrodes. Also, patch geometry affected the strength of the virtual electrodes. Our simulations suggest that increased fibroblast-myocyte coupling and intra-fibroblast conductivity reduce virtual electrode strength. However, experimental data to constrain these modeling parameters are limited and thus pinpointing the magnitude of the reduction will require further understanding of electrical coupling of fibroblasts in native cardiac tissues. We propose that the findings from our computational studies are important for development of patient-specific protocols for internal defibrillators.
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Affiliation(s)
- Jean Bragard
- Department of Physics and Applied Mathematics, University of Navarra, Pamplona, Spain
| | - Aparna C. Sankarankutty
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
| | - Frank B. Sachse
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, United States
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
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16
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Morotti S, Grandi E. Quantitative systems models illuminate arrhythmia mechanisms in heart failure: Role of the Na + -Ca 2+ -Ca 2+ /calmodulin-dependent protein kinase II-reactive oxygen species feedback. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2018; 11:e1434. [PMID: 30015404 DOI: 10.1002/wsbm.1434] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 05/29/2018] [Accepted: 06/16/2018] [Indexed: 12/22/2022]
Abstract
Quantitative systems modeling aims to integrate knowledge in different research areas with models describing biological mechanisms and dynamics to gain a better understanding of complex clinical syndromes. Heart failure (HF) is a chronic complex cardiac disease that results from structural or functional disorders impairing the ability of the ventricle to fill with or eject blood. Highly interactive and dynamic changes in mechanical, structural, neurohumoral, metabolic, and electrophysiological properties collectively predispose the failing heart to cardiac arrhythmias, which are responsible for about a half of HF deaths. Multiscale cardiac modeling and simulation integrate structural and functional data from HF experimental models and patients to improve our mechanistic understanding of this complex arrhythmia syndrome. In particular, they allow investigating how disease-induced remodeling alters the coupling of electrophysiology, Ca2+ and Na+ handling, contraction, and energetics that lead to rhythm derangements. The Ca2+ /calmodulin-dependent protein kinase II, which expression and activity are enhanced in HF, emerges as a critical hub that modulates the feedbacks between these various subsystems and promotes arrhythmogenesis. This article is categorized under: Physiology > Mammalian Physiology in Health and Disease Models of Systems Properties and Processes > Mechanistic Models Models of Systems Properties and Processes > Cellular Models Models of Systems Properties and Processes > Organ, Tissue, and Physiological Models.
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Affiliation(s)
- Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, California
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California
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17
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Klesen A, Jakob D, Emig R, Kohl P, Ravens U, Peyronnet R. Cardiac fibroblasts : Active players in (atrial) electrophysiology? Herzschrittmacherther Elektrophysiol 2018; 29:62-69. [PMID: 29392412 DOI: 10.1007/s00399-018-0553-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 12/22/2017] [Accepted: 12/22/2017] [Indexed: 06/07/2023]
Abstract
Fibrotic areas in cardiac muscle-be it in ventricular or atrial tissue-are considered as obstacles for conduction of the excitatory wave and can therefore facilitate re-entry, which may contribute to the sustenance of cardiac arrhythmias. Persistence of one of the most frequent arrhythmias, atrial fibrillation (AF), is accompanied by enhanced atrial fibrosis. Any kind of myocardial perturbation, whether via mechanical stress or ischemic damage, inflammation, or irregular and high-frequency electrical activity, activates fibroblasts. This leads to the secretion of paracrine factors and extracellular matrix proteins, especially collagen, and to the differentiation of fibroblasts into myofibroblasts. Excessive collagen production is the hallmark of fibrosis and impairs regular impulse propagation. In addition, direct electrical coupling between cardiomyocytes and nonmyocytes, such as fibroblasts and macrophages, via gap junctions affects conduction. Although fibroblasts are not electrically excitable, they express functional ion channels, in particular K+ channels and mechanosensitive channels, some of which could be involved in tissue remodeling. Here, we briefly review these aspects with special reference to AF.
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Affiliation(s)
- Alexander Klesen
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center-University of Freiburg, Elsässer Str. 2q, 79110, Freiburg i. Br., Germany
- Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Dorothee Jakob
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center-University of Freiburg, Elsässer Str. 2q, 79110, Freiburg i. Br., Germany
- Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Ramona Emig
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center-University of Freiburg, Elsässer Str. 2q, 79110, Freiburg i. Br., Germany
- Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center-University of Freiburg, Elsässer Str. 2q, 79110, Freiburg i. Br., Germany
- Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Ursula Ravens
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center-University of Freiburg, Elsässer Str. 2q, 79110, Freiburg i. Br., Germany
- Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany
| | - Rémi Peyronnet
- Institute for Experimental Cardiovascular Medicine, University Heart Center, Medical Center-University of Freiburg, Elsässer Str. 2q, 79110, Freiburg i. Br., Germany.
- Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany.
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18
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Hulsmans M, Clauss S, Xiao L, Aguirre AD, King KR, Hanley A, Hucker WJ, Wülfers EM, Seemann G, Courties G, Iwamoto Y, Sun Y, Savol AJ, Sager HB, Lavine KJ, Fishbein GA, Capen DE, Da Silva N, Miquerol L, Wakimoto H, Seidman CE, Seidman JG, Sadreyev RI, Naxerova K, Mitchell RN, Brown D, Libby P, Weissleder R, Swirski FK, Kohl P, Vinegoni C, Milan DJ, Ellinor PT, Nahrendorf M. Macrophages Facilitate Electrical Conduction in the Heart. Cell 2017; 169:510-522.e20. [PMID: 28431249 DOI: 10.1016/j.cell.2017.03.050] [Citation(s) in RCA: 636] [Impact Index Per Article: 90.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/19/2017] [Accepted: 03/31/2017] [Indexed: 12/11/2022]
Abstract
Organ-specific functions of tissue-resident macrophages in the steady-state heart are unknown. Here, we show that cardiac macrophages facilitate electrical conduction through the distal atrioventricular node, where conducting cells densely intersperse with elongated macrophages expressing connexin 43. When coupled to spontaneously beating cardiomyocytes via connexin-43-containing gap junctions, cardiac macrophages have a negative resting membrane potential and depolarize in synchrony with cardiomyocytes. Conversely, macrophages render the resting membrane potential of cardiomyocytes more positive and, according to computational modeling, accelerate their repolarization. Photostimulation of channelrhodopsin-2-expressing macrophages improves atrioventricular conduction, whereas conditional deletion of connexin 43 in macrophages and congenital lack of macrophages delay atrioventricular conduction. In the Cd11bDTR mouse, macrophage ablation induces progressive atrioventricular block. These observations implicate macrophages in normal and aberrant cardiac conduction.
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Affiliation(s)
- Maarten Hulsmans
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Sebastian Clauss
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Department of Medicine I, University Hospital Munich, Campus Grosshadern, Ludwig-Maximilians University Munich, 81377 Munich, Germany; DZHK German Center for Cardiovascular Research, Partner Site Munich, Munich Heart Alliance, Munich, Germany
| | - Ling Xiao
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Aaron D Aguirre
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Kevin R King
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Alan Hanley
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Cardiovascular Research Center, National University of Ireland Galway, Galway, Ireland
| | - William J Hucker
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Eike M Wülfers
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg, Bad Krozingen, 79110 Freiburg, Germany; Faculty of Medicine, Albert-Ludwigs University, 79110 Freiburg, Germany
| | - Gunnar Seemann
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg, Bad Krozingen, 79110 Freiburg, Germany; Faculty of Medicine, Albert-Ludwigs University, 79110 Freiburg, Germany
| | - Gabriel Courties
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Yoshiko Iwamoto
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Yuan Sun
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Andrej J Savol
- Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Hendrik B Sager
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Kory J Lavine
- Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Gregory A Fishbein
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Diane E Capen
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Nicolas Da Silva
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Lucile Miquerol
- Aix Marseille University, CNRS, IBDM, 13288 Marseille, France
| | - Hiroko Wakimoto
- Division of Genetics, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Christine E Seidman
- Division of Genetics, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Jonathan G Seidman
- Division of Genetics, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Ruslan I Sadreyev
- Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Kamila Naxerova
- Division of Genetics, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Richard N Mitchell
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Dennis Brown
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Peter Libby
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Ralph Weissleder
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Filip K Swirski
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg, Bad Krozingen, 79110 Freiburg, Germany; Faculty of Medicine, Albert-Ludwigs University, 79110 Freiburg, Germany; Cardiac Biophysics and Systems Biology, National Heart and Lung Institute, Imperial College London, London SW36NP, UK
| | - Claudio Vinegoni
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - David J Milan
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Program in Population and Medical Genetics, The Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Patrick T Ellinor
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Program in Population and Medical Genetics, The Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Matthias Nahrendorf
- Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
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19
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Sridhar S, Vandersickel N, Panfilov AV. Effect of myocyte-fibroblast coupling on the onset of pathological dynamics in a model of ventricular tissue. Sci Rep 2017; 7:40985. [PMID: 28106124 PMCID: PMC5247688 DOI: 10.1038/srep40985] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 12/13/2016] [Indexed: 12/23/2022] Open
Abstract
Managing lethal cardiac arrhythmias is one of the biggest challenges in modern cardiology, and hence it is very important to understand the factors underlying such arrhythmias. While early afterdepolarizations (EAD) of cardiac cells is known to be one such arrhythmogenic factor, the mechanisms underlying the emergence of tissue level arrhythmias from cellular level EADs is not fully understood. Another known arrhythmogenic condition is fibrosis of cardiac tissue that occurs both due to aging and in many types of heart diseases. In this paper we describe the results of a systematic in-silico study, using the TNNP model of human cardiac cells and MacCannell model for (myo)fibroblasts, on the possible effects of diffuse fibrosis on arrhythmias occurring via EADs. We find that depending on the resting potential of fibroblasts (VFR), M-F coupling can either increase or decrease the region of parameters showing EADs. Fibrosis increases the probability of occurrence of arrhythmias after a single focal stimulation and this effect increases with the strength of the M-F coupling. While in our simulations, arrhythmias occur due to fibrosis induced ectopic activity, we do not observe any specific fibrotic pattern that promotes the occurrence of these ectopic sources.
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Affiliation(s)
- S. Sridhar
- Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - Nele Vandersickel
- Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - Alexander V. Panfilov
- Department of Physics and Astronomy, Ghent University, Ghent, Belgium
- Moscow Institute of Physics and Technology (State University), Dolgoprudny, Moscow Region, Russia
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20
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Can UI, Nagarajan N, Vural DC, Zorlutuna P. Muscle-Cell-Based "Living Diodes". ACTA ACUST UNITED AC 2017; 1:e1600035. [PMID: 32646185 DOI: 10.1002/adbi.201600035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Indexed: 12/14/2022]
Abstract
A new type of diode that is made entirely of electrically excitable muscle cells and nonexcitable fibroblast cells is designed, fabricated, and characterized. These two cell types in a rectangular pattern allow the signal initiated on the excitable side to pass to the nonexcitable side, and not in the opposite direction.
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Affiliation(s)
- Uryan Isik Can
- Aerospace and Mechanical Engineering Department, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Neerajha Nagarajan
- Aerospace and Mechanical Engineering Department, Bioengineering Graduate Program, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Dervis Can Vural
- Department of Physics, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Pinar Zorlutuna
- Aerospace and Mechanical Engineering Department, University of Notre Dame, Notre Dame, IN, 46556, USA.,Aerospace and Mechanical Engineering Department, Bioengineering Graduate Program, University of Notre Dame, Notre Dame, IN, 46556, USA
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21
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Jousset F, Maguy A, Rohr S, Kucera JP. Myofibroblasts Electrotonically Coupled to Cardiomyocytes Alter Conduction: Insights at the Cellular Level from a Detailed In silico Tissue Structure Model. Front Physiol 2016; 7:496. [PMID: 27833567 PMCID: PMC5081362 DOI: 10.3389/fphys.2016.00496] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 10/11/2016] [Indexed: 01/05/2023] Open
Abstract
Fibrotic myocardial remodeling is typically accompanied by the appearance of myofibroblasts (MFBs). In vitro, MFBs were shown to slow conduction and precipitate ectopic activity following gap junctional coupling to cardiomyocytes (CMCs). To gain further mechanistic insights into this arrhythmogenic MFB-CMC crosstalk, we performed numerical simulations in cell-based high-resolution two-dimensional tissue models that replicated experimental conditions. Cell dimensions were determined using confocal microscopy of single and co-cultured neonatal rat ventricular CMCs and MFBs. Conduction was investigated as a function of MFB density in three distinct cellular tissue architectures: CMC strands with endogenous MFBs, CMC strands with coating MFBs of two different sizes, and CMC strands with MFB inserts. Simulations were performed to identify individual contributions of heterocellular gap junctional coupling and of the specific electrical phenotype of MFBs. With increasing MFB density, both endogenous and coating MFBs slowed conduction. At MFB densities of 5-30%, conduction slowing was most pronounced in strands with endogenous MFBs due to the MFB-dependent increase in axial resistance. At MFB densities >40%, very slow conduction and spontaneous activity was primarily due to MFB-induced CMC depolarization. Coating MFBs caused non-uniformities of resting membrane potential, which were more prominent with large than with small MFBs. In simulations of MFB inserts connecting two CMC strands, conduction delays increased with increasing insert lengths and block appeared for inserts >1.2 mm. Thus, electrophysiological properties of engineered CMC-MFB co-cultures depend on MFB density, MFB size and their specific positioning in respect to CMCs. These factors may influence conduction characteristics in the heterocellular myocardium.
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Affiliation(s)
- Florian Jousset
- Department of Physiology, University of Bern Bern, Switzerland
| | - Ange Maguy
- Department of Physiology, University of Bern Bern, Switzerland
| | - Stephan Rohr
- Department of Physiology, University of Bern Bern, Switzerland
| | - Jan P Kucera
- Department of Physiology, University of Bern Bern, Switzerland
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22
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Spencer TM, Blumenstein RF, Pryse KM, Lee SL, Glaubke DA, Carlson BE, Elson EL, Genin GM. Fibroblasts Slow Conduction Velocity in a Reconstituted Tissue Model of Fibrotic Cardiomyopathy. ACS Biomater Sci Eng 2016; 3:3022-3028. [PMID: 31119190 DOI: 10.1021/acsbiomaterials.6b00576] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Myocardial function deteriorates over the course of fibrotic cardiomyopathy, due to electrophysiological and mechanical effects of myofibroblasts that are not completely understood. Although a range of experimental model systems and associated theoretical treatments exist at the levels of isolated cardiomyocytes and planar co-cultures of myofibroblasts and cardiomyocytes, interactions between these cell types at the tissue level are less clear. We studied these interactions through an engineered heart tissue (EHT) model of fibrotic myocardium and a mathematical model of the effects of cellular composition on EHT impulse conduction velocity. The EHT model allowed for modulation of cardiomyocyte and myofibroblast volume fractions, and observation of cell behavior in a three-dimensional environment that is more similar to native heart tissue than is planar cell culture. The cardiomyocyte and myofibroblast volume fractions determined the retardation of impulse conduction (spread of the action potential) in EHTs as measured by changes of the fluorescence of the Ca2+ probe, Fluo-2. Interpretation through our model showed retardation far in excess of predictions by homogenization theory, with conduction ceasing far below the fibroblast volume fraction associated with steric percolation. Results point to an important multiscale structural role of myofibroblasts in attenuating impulse conduction in fibrotic cardiomyopathy.
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Affiliation(s)
- Teresa M Spencer
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA
| | - Ryan F Blumenstein
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA
| | - Kenneth M Pryse
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA.,Department of Biochemistry and Molecular Biophysics, 660 S. Euclid Drive, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Sheng-Lin Lee
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA
| | - David A Glaubke
- Department of Biomedical Engineering, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA
| | - Brian E Carlson
- Department of Molecular and Integrative Physiology, NCRC B10 A126, 2800 Plymouth Rd., University of Michigan School of Medicine, Ann Arbor, MI 48105, USA
| | - Elliot L Elson
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA.,Department of Biochemistry and Molecular Biophysics, 660 S. Euclid Drive, Washington University School of Medicine, St. Louis, MO 63110, USA.,Department of Biomedical Engineering, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA
| | - Guy M Genin
- Department of Mechanical Engineering and Materials Science, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA.,NSF Center for Engineering MechanoBiology, 1 Brookings Drive, Washington University in St. Louis, St. Louis, MO 63130 USA
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23
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Mayourian J, Savizky RM, Sobie EA, Costa KD. Modeling Electrophysiological Coupling and Fusion between Human Mesenchymal Stem Cells and Cardiomyocytes. PLoS Comput Biol 2016; 12:e1005014. [PMID: 27454812 PMCID: PMC4959759 DOI: 10.1371/journal.pcbi.1005014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 06/08/2016] [Indexed: 01/16/2023] Open
Abstract
Human mesenchymal stem cell (hMSC) delivery has demonstrated promise in preclinical and clinical trials for myocardial infarction therapy; however, broad acceptance is hindered by limited understanding of hMSC-human cardiomyocyte (hCM) interactions. To better understand the electrophysiological consequences of direct heterocellular connections between hMSCs and hCMs, three original mathematical models were developed, representing an experimentally verified triad of hMSC families with distinct functional ion channel currents. The arrhythmogenic risk of such direct electrical interactions in the setting of healthy adult myocardium was predicted by coupling and fusing these hMSC models to the published ten Tusscher midcardial hCM model. Substantial variations in action potential waveform—such as decreased action potential duration (APD) and plateau height—were found when hCMs were coupled to the two hMSC models expressing functional delayed rectifier-like human ether à-go-go K+ channel 1 (hEAG1); the effects were exacerbated for fused hMSC-hCM hybrid cells. The third family of hMSCs (Type C), absent of hEAG1 activity, led to smaller single-cell action potential alterations during coupling and fusion, translating to longer tissue-level mean action potential wavelength. In a simulated 2-D monolayer of cardiac tissue, re-entry vulnerability with low (5%) hMSC insertion was approximately eight-fold lower with Type C hMSCs compared to hEAG1-functional hMSCs. A 20% decrease in APD dispersion by Type C hMSCs compared to hEAG1-active hMSCs supports the claim of reduced arrhythmogenic potential of this cell type with low hMSC insertion. However, at moderate (15%) and high (25%) hMSC insertion, the vulnerable window increased independent of hMSC type. In summary, this study provides novel electrophysiological models of hMSCs, predicts possible arrhythmogenic effects of hMSCs when directly coupled to healthy hCMs, and proposes that isolating a subset of hMSCs absent of hEAG1 activity may offer increased safety as a cell delivery cardiotherapy at low levels of hMSC-hCM coupling. Myocardial infarction—better known as a heart attack—strikes on average every 43 seconds in America. An emerging approach to treat myocardial infarction patients involves the delivery of human mesenchymal stem cells (hMSCs) to the damaged heart. While clinical trials of this therapeutic approach have yet to report adverse effects on heart electrical rhythm, such consequences have been implicated in simpler experimental systems and thus remain a concern. In this study, we utilized mathematical modeling to simulate electrical interactions arising from direct coupling between hMSCs and human heart cells to develop insight into the possible adverse effects of this therapeutic approach on human heart electrical activity, and to assess a novel strategy for reducing some potential risks of this therapy. We developed the first mathematical models of electrical activity of three families of hMSCs based on published experimental data, and integrated these with previously established mathematical models of human heart cell electrical activity. Our computer simulations demonstrated that one particular family of hMSCs minimized the disturbances in cardiac electrical activity both at the single-cell and tissue levels, suggesting that isolating this specific sub-population of hMSCs for myocardial delivery could potentially increase the safety of future hMSC-based heart therapies.
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Affiliation(s)
- Joshua Mayourian
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Ruben M. Savizky
- Department of Chemistry, The Cooper Union, New York, New York, United States of America
| | - Eric A. Sobie
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Kevin D. Costa
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail:
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24
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Novel therapeutic strategies targeting fibroblasts and fibrosis in heart disease. Nat Rev Drug Discov 2016; 15:620-638. [PMID: 27339799 DOI: 10.1038/nrd.2016.89] [Citation(s) in RCA: 220] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Our understanding of the functions of cardiac fibroblasts has moved beyond their roles in heart structure and extracellular matrix generation and now includes their contributions to paracrine, mechanical and electrical signalling during ontogenesis and normal cardiac activity. Fibroblasts also have central roles in pathogenic remodelling during myocardial ischaemia, hypertension and heart failure. As key contributors to scar formation, they are crucial for tissue repair after interventions including surgery and ablation. Novel experimental approaches targeting cardiac fibroblasts are promising potential therapies for heart disease. Indeed, several existing drugs act, at least partially, through effects on cardiac connective tissue. This Review outlines the origins and roles of fibroblasts in cardiac development, homeostasis and disease; illustrates the involvement of fibroblasts in current and emerging clinical interventions; and identifies future targets for research and development.
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25
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Arevalo HJ, Boyle PM, Trayanova NA. Computational rabbit models to investigate the initiation, perpetuation, and termination of ventricular arrhythmia. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 121:185-94. [PMID: 27334789 DOI: 10.1016/j.pbiomolbio.2016.06.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 06/13/2016] [Indexed: 12/29/2022]
Abstract
Current understanding of cardiac electrophysiology has been greatly aided by computational work performed using rabbit ventricular models. This article reviews the contributions of multiscale models of rabbit ventricles in understanding cardiac arrhythmia mechanisms. This review will provide an overview of multiscale modeling of the rabbit ventricles. It will then highlight works that provide insights into the role of the conduction system, complex geometric structures, and heterogeneous cellular electrophysiology in diseased and healthy rabbit hearts to the initiation and maintenance of ventricular arrhythmia. Finally, it will provide an overview on the contributions of rabbit ventricular modeling on understanding the mechanisms underlying shock-induced defibrillation.
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Affiliation(s)
- Hermenegild J Arevalo
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA; Simula Research Laboratory, Oslo, Norway
| | - Patrick M Boyle
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Natalia A Trayanova
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA.
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26
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Greisas A, Zlochiver S. The Multi-Domain Fibroblast/Myocyte Coupling in the Cardiac Tissue: A Theoretical Study. Cardiovasc Eng Technol 2016; 7:290-304. [PMID: 27150222 DOI: 10.1007/s13239-016-0266-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 04/29/2016] [Indexed: 02/02/2023]
Abstract
Cardiac fibroblast proliferation and concomitant collagenous matrix accumulation (fibrosis) develop during multiple cardiac pathologies. Recent studies have demonstrated direct electrical coupling between myocytes and fibroblasts in vitro, and assessed the electrophysiological implications of such coupling. However, in the living tissues, such coupling has not been demonstrated, and only indirect coupling via the extracellular space is likely to exist. In this study we employed a multi-domain model to assess the modulation of the cardiac electrophysiological properties by neighboring fibroblasts assuming only indirect coupling. Numerical simulations in 1D and 2D human atrial models showed that extracellular coupling sustains a significant impact on conduction velocity (CV) and a less significant effect on the action potential duration. Both CV and the slope of the CV restitution increased with increasing fibroblast density. This effect was more substantial for lower extracellular conductance. In 2D, spiral waves exhibited reduced frequency with increasing fibroblast density, and the propensity of wavebreaks and complex dynamics at high pacing rates significantly increased.
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Affiliation(s)
- Ariel Greisas
- Department of Biomedical Engineering, Faculty of Engineering, Tel-Aviv University, Ramat-Aviv, 69978, Tel-Aviv, Israel
| | - Sharon Zlochiver
- Department of Biomedical Engineering, Faculty of Engineering, Tel-Aviv University, Ramat-Aviv, 69978, Tel-Aviv, Israel.
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27
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Zeigler AC, Richardson WJ, Holmes JW, Saucerman JJ. Computational modeling of cardiac fibroblasts and fibrosis. J Mol Cell Cardiol 2016; 93:73-83. [PMID: 26608708 PMCID: PMC4846515 DOI: 10.1016/j.yjmcc.2015.11.020] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/18/2015] [Accepted: 11/18/2015] [Indexed: 12/31/2022]
Abstract
Altered fibroblast behavior can lead to pathologic changes in the heart such as arrhythmia, diastolic dysfunction, and systolic dysfunction. Computational models are increasingly used as a tool to identify potential mechanisms driving a phenotype or potential therapeutic targets against an unwanted phenotype. Here we review how computational models incorporating cardiac fibroblasts have clarified the role for these cells in electrical conduction and tissue remodeling in the heart. Models of fibroblast signaling networks have primarily focused on fibroblast cell lines or fibroblasts from other tissues rather than cardiac fibroblasts, specifically, but they are useful for understanding how fundamental signaling pathways control fibroblast phenotype. In the future, modeling cardiac fibroblast signaling, incorporating -omics and drug-interaction data into signaling network models, and utilizing multi-scale models will improve the ability of in silico studies to predict potential therapeutic targets against adverse cardiac fibroblast activity.
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Affiliation(s)
- Angela C Zeigler
- University of Virginia, Biomedical Engineering Department, 415 Lane Road, Charlottesville, VA 22903, USA.
| | - William J Richardson
- University of Virginia, Biomedical Engineering Department, 415 Lane Road, Charlottesville, VA 22903, USA.
| | - Jeffrey W Holmes
- University of Virginia, Biomedical Engineering Department, 415 Lane Road, Charlottesville, VA 22903, USA.
| | - Jeffrey J Saucerman
- University of Virginia, Biomedical Engineering Department, 415 Lane Road, Charlottesville, VA 22903, USA.
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28
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Abstract
Myocardial fibrosis is a significant global health problem associated with nearly all forms of heart disease. Cardiac fibroblasts comprise an essential cell type in the heart that is responsible for the homeostasis of the extracellular matrix; however, upon injury, these cells transform to a myofibroblast phenotype and contribute to cardiac fibrosis. This remodeling involves pathological changes that include chamber dilation, cardiomyocyte hypertrophy and apoptosis, and ultimately leads to the progression to heart failure. Despite the critical importance of fibrosis in cardiovascular disease, our limited understanding of the cardiac fibroblast impedes the development of potential therapies that effectively target this cell type and its pathological contribution to disease progression. This review summarizes current knowledge regarding the origins and roles of fibroblasts, mediators and signaling pathways known to influence fibroblast function after myocardial injury, as well as novel therapeutic strategies under investigation to attenuate cardiac fibrosis.
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Affiliation(s)
- Joshua G Travers
- From the Heart Institute, Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, OH
| | - Fadia A Kamal
- From the Heart Institute, Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, OH
| | - Jeffrey Robbins
- From the Heart Institute, Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, OH
| | - Katherine E Yutzey
- From the Heart Institute, Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, OH
| | - Burns C Blaxall
- From the Heart Institute, Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, OH.
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29
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Ongstad E, Kohl P. Fibroblast-myocyte coupling in the heart: Potential relevance for therapeutic interventions. J Mol Cell Cardiol 2016; 91:238-46. [PMID: 26774702 DOI: 10.1016/j.yjmcc.2016.01.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 01/09/2016] [Accepted: 01/11/2016] [Indexed: 01/03/2023]
Abstract
Cardiac myocyte-fibroblast electrotonic coupling is a well-established fact in vitro. Indirect evidence of its presence in vivo exists, but few functional studies have been published. This review describes the current knowledge of fibroblast-myocyte electrical signaling in the heart. Further research is needed to understand the frequency and extent of heterocellular interactions in vivo in order to gain a better understanding of their relevance in healthy and diseased myocardium. It is hoped that associated insight into myocyte-fibroblast coupling in the heart may lead to the discovery of novel therapeutic targets and the development of agents for improving outcomes of myocardial scarring and fibrosis.
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Affiliation(s)
- Emily Ongstad
- Clemson University, Department of Bioengineering, Clemson, SC, USA; Virginia Tech Carilion Research Institute, Roanoke, VA, USA.
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg - Bad Krozingen, Faculty of Medicine, University Freiburg, Germany; Cardiac Biophysics and Systems Biology, National Heart and Lung Institute, Imperial College London, UK
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30
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Shim W. Myocardial Telocytes: A New Player in Electric Circuitry of the Heart. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 913:241-251. [PMID: 27796892 DOI: 10.1007/978-981-10-1061-3_16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The heart is an electrically conducting organ with networked bioelectric currents that transverse a large segment of interstitial space interspersed with the muscular parenchyma. Non-excitable connective cells in the interstitial space contributed importantly to many structural, biochemical, and physiological activities of cardiac homeostasis. However, contribution of interstitial cells in the cardiac niche has long been neglected. Telocyte is recently recognized as a distinct class of interstitial cell that resides in a wide array of tissues including in the epicardium, myocardium, and endocardium of the heart. They are increasingly described to conduct ionic currents that may have significant implications in bioelectric signaling. In this review, we highlight the significance of telocytes in such connectivity and conductivity within the interstitial bioelectric network in tissue homeostasis.
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Affiliation(s)
- Winston Shim
- National Heart Research Institute Singapore, 5 Hospital Drive, National Heart Centre Singapore, Singapore, 169609, Singapore.
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore.
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31
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Gomez JF, Cardona K, Trenor B. Lessons learned from multi-scale modeling of the failing heart. J Mol Cell Cardiol 2015; 89:146-59. [PMID: 26476237 DOI: 10.1016/j.yjmcc.2015.10.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 10/07/2015] [Accepted: 10/14/2015] [Indexed: 12/26/2022]
Abstract
Heart failure constitutes a major public health problem worldwide. Affected patients experience a number of changes in the electrical function of the heart that predispose to potentially lethal cardiac arrhythmias. Due to the multitude of electrophysiological changes that may occur during heart failure, the scientific literature is complex and sometimes ambiguous, perhaps because these findings are highly dependent on the etiology, the stage of heart failure, and the experimental model used to study these changes. Nevertheless, a number of common features of failing hearts have been documented. Prolongation of the action potential (AP) involving ion channel remodeling and alterations in calcium handling have been established as the hallmark characteristics of myocytes isolated from failing hearts. Intercellular uncoupling and fibrosis are identified as major arrhythmogenic factors. Multi-scale computational simulations are a powerful tool that complements experimental and clinical research. The development of biophysically detailed computer models of single myocytes and cardiac tissues has contributed greatly to our understanding of processes underlying excitation and repolarization in the heart. The electrical, structural, and metabolic remodeling that arises in cardiac tissues during heart failure has been addressed from different computational perspectives to further understand the arrhythmogenic substrate. This review summarizes the contributions from computational modeling and simulation to predict the underlying mechanisms of heart failure phenotypes and their implications for arrhythmogenesis, ranging from the cellular level to whole-heart simulations. The main aspects of heart failure are presented in several related sections. An overview of the main electrophysiological and structural changes that have been observed experimentally in failing hearts is followed by the description and discussion of the simulation work in this field at the cellular level, and then in 2D and 3D cardiac structures. The implications for arrhythmogenesis in heart failure are also discussed including therapeutic measures, such as drug effects and cardiac resynchronization therapy. Finally, the future challenges in heart failure modeling and simulation will be discussed.
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Affiliation(s)
- Juan F Gomez
- Instituto de Investigación Interuniversitario en Bioingeniería y Tecnología Orientada, al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
| | - Karen Cardona
- Instituto de Investigación Interuniversitario en Bioingeniería y Tecnología Orientada, al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
| | - Beatriz Trenor
- Instituto de Investigación Interuniversitario en Bioingeniería y Tecnología Orientada, al Ser Humano (I3BH), Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
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32
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Computational Approaches to Understanding the Role of Fibroblast-Myocyte Interactions in Cardiac Arrhythmogenesis. BIOMED RESEARCH INTERNATIONAL 2015; 2015:465714. [PMID: 26601107 PMCID: PMC4637154 DOI: 10.1155/2015/465714] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 04/10/2015] [Accepted: 04/29/2015] [Indexed: 11/18/2022]
Abstract
The adult heart is composed of a dense network of cardiomyocytes surrounded by nonmyocytes, the most
abundant of which are cardiac fibroblasts. Several cardiac diseases, such as myocardial infarction or dilated
cardiomyopathy, are associated with an increased density of fibroblasts, that is, fibrosis. Fibroblasts play a
significant role in the development of electrical and mechanical dysfunction of the heart; however the underlying
mechanisms are only partially understood. One widely studied mechanism suggests that fibroblasts produce
excess extracellular matrix, resulting in collagenous septa. These collagenous septa slow propagation, cause
zig-zag conduction paths, and decouple cardiomyocytes resulting in a substrate for arrhythmia. Another
emerging mechanism suggests that fibroblasts promote arrhythmogenesis through direct electrical interactions
with cardiomyocytes via gap junctions. Due to the challenges of investigating fibroblast-myocyte coupling in
native cardiac tissue, computational modeling and in vitro experiments have facilitated the investigation into the
mechanisms underlying fibroblast-mediated changes in cardiomyocyte action potential morphology, conduction
velocity, spontaneous excitability, and vulnerability to reentry. In this paper, we summarize the major findings of
the existing computational studies investigating the implications of fibroblast-myocyte interactions in the normal
and diseased heart. We then present investigations from our group into the potential role of voltage-dependent
gap junctions in fibroblast-myocyte interactions.
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33
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Zhan HQ, Xia L, Shou GF, Zang YL, Liu F, Crozier S. Fibroblast proliferation alters cardiac excitation conduction and contraction: a computational study. J Zhejiang Univ Sci B 2014; 15:225-42. [PMID: 24599687 DOI: 10.1631/jzus.b1300156] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In this study, the effects of cardiac fibroblast proliferation on cardiac electric excitation conduction and mechanical contraction were investigated using a proposed integrated myocardial-fibroblastic electromechanical model. At the cellular level, models of the human ventricular myocyte and fibroblast were modified to incorporate a model of cardiac mechanical contraction and cooperativity mechanisms. Cellular electromechanical coupling was realized with a calcium buffer. At the tissue level, electrical excitation conduction was coupled to an elastic mechanics model in which the finite difference method (FDM) was used to solve electrical excitation equations, and the finite element method (FEM) was used to solve mechanics equations. The electromechanical properties of the proposed integrated model were investigated in one or two dimensions under normal and ischemic pathological conditions. Fibroblast proliferation slowed wave propagation, induced a conduction block, decreased strains in the fibroblast proliferous tissue, and increased dispersions in depolarization, repolarization, and action potential duration (APD). It also distorted the wave-front, leading to the initiation and maintenance of re-entry, and resulted in a sustained contraction in the proliferous areas. This study demonstrated the important role that fibroblast proliferation plays in modulating cardiac electromechanical behaviour and which should be considered in planning future heart-modeling studies.
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Affiliation(s)
- He-qing Zhan
- Department of Biomedical Engineering, Zhejiang University, Hangzhou 310027, China; School of Information Technology and Electrical Engineering, the University of Queensland, Brisbane QLD 4072, Australia
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34
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Ferrero JM, Trenor B, Romero L. Multiscale computational analysis of the bioelectric consequences of myocardial ischaemia and infarction. Europace 2014; 16:405-15. [PMID: 24569895 DOI: 10.1093/europace/eut405] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Ischaemic heart disease is considered as the single most frequent cause of death, provoking more than 7 000 000 deaths every year worldwide. A high percentage of patients experience sudden cardiac death, caused in most cases by tachyarrhythmic mechanisms associated to myocardial ischaemia and infarction. These diseases are difficult to study using solely experimental means due to their complex dynamics and unstable nature. In the past decades, integrative computational simulation techniques have become a powerful tool to complement experimental and clinical research when trying to elucidate the intimate mechanisms of ischaemic electrophysiological processes and to aid the clinician in the improvement and optimization of therapeutic procedures. The purpose of this paper is to briefly review some of the multiscale computational models of myocardial ischaemia and infarction developed in the past 20 years, ranging from the cellular level to whole-heart simulations.
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Affiliation(s)
- Jose M Ferrero
- Departamento de Ingeniería Electrónica, Instituto I3BH, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain
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35
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Petrov VS, Osipov GV. Interaction-based transition from passivity to excitability. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:032916. [PMID: 25314513 DOI: 10.1103/physreve.90.032916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Indexed: 06/04/2023]
Abstract
In this paper we study the process of transition from passive to excitable behavior due to interaction between nonlinear dynamical systems. We show that under certain conditions a passive unit may demonstrate qualitatively new excitable dynamics. We study the properties of an excitable medium constructed on the basis of the proposed transition. The effects are demonstrated with the realistic Luo-Rudy model. Application to the cardiac dynamics and functioning is discussed. The qualitative analytic and numerical description is also given for the phenomenological FitzHugh-Nagumo system.
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Affiliation(s)
- V S Petrov
- Nizhny Novgorod State University, Nizhny Novgorod, Russia
| | - G V Osipov
- Nizhny Novgorod State University, Nizhny Novgorod, Russia
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36
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Koivumäki JT, Clark RB, Belke D, Kondo C, Fedak PWM, Maleckar MMC, Giles WR. Na(+) current expression in human atrial myofibroblasts: identity and functional roles. Front Physiol 2014; 5:275. [PMID: 25147525 PMCID: PMC4124488 DOI: 10.3389/fphys.2014.00275] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 07/07/2014] [Indexed: 12/19/2022] Open
Abstract
In the mammalian heart fibroblasts have important functional roles in both healthy conditions and diseased states. During pathophysiological challenges, a closely related myofibroblast cell population emerges, and can have distinct, significant roles. Recently, it has been reported that human atrial myofibroblasts can express a Na+ current, INa. Some of the biophysical properties and molecular features suggest that this INa is due to expression of Nav 1.5, the same Na+ channel α subunit that generates the predominant INa in myocytes from adult mammalian heart. In principle, expression of Nav 1.5 could give rise to regenerative action potentials in the fibroblasts/myofibroblasts. This would suggest an active as opposed to passive role for fibroblasts/myofibroblasts in both the “trigger” and the “substrate” components of cardiac rhythm disturbances. Our goals in this preliminary study were: (i) to confirm and extend the electrophysiological characterization of INa in a human atrial fibroblast/myofibroblast cell population maintained in conventional 2-D tissue culture; (ii) to identify key molecular properties of the α and β subunits of these Na+ channel(s); (iii) to define the biophysical and pharmacological properties of this INa; (iv) to integrate the available multi-disciplinary data, and attempt to illustrate its functional consequences, using a mathematical model in which the human atrial myocyte is coupled via connexins to fixed numbers of fibroblasts/myofibroblasts in a syncytial arrangement. Our experimental findings confirm that a significant fraction (approximately 40–50%) of these human atrial myofibroblasts can express INa. However, our data suggest that INa may be generated by a combination of Nav 1.9, Nav 1.2, and Nav 1.5. Our results, when complemented with mathematical modeling, provide a background for re-evaluating pharmacological management of supraventricular rhythm disorders, e.g., persistent atrial fibrillation.
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Affiliation(s)
- Jussi T Koivumäki
- Simula Research Laboratory, Center for Biomedical Computing and Center for Cardiological Innovation Oslo, Norway
| | - Robert B Clark
- Faculty of Kinesiology, University of Calgary Calgary, AB, Canada
| | - Darrell Belke
- Faculty of Kinesiology, University of Calgary Calgary, AB, Canada
| | - Colleen Kondo
- Faculty of Kinesiology, University of Calgary Calgary, AB, Canada
| | - Paul W M Fedak
- Division of Cardiothoracic Surgery, Department of Cardiac Sciences, University of Calgary Calgary, AB, Canada
| | - Mary M C Maleckar
- Simula Research Laboratory, Center for Biomedical Computing and Center for Cardiological Innovation Oslo, Norway
| | - Wayne R Giles
- Faculty of Kinesiology, University of Calgary Calgary, AB, Canada
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Gomez JF, Cardona K, Martinez L, Saiz J, Trenor B. Electrophysiological and structural remodeling in heart failure modulate arrhythmogenesis. 2D simulation study. PLoS One 2014; 9:e103273. [PMID: 25054335 PMCID: PMC4108391 DOI: 10.1371/journal.pone.0103273] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 06/30/2014] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Heart failure is operationally defined as the inability of the heart to maintain blood flow to meet the needs of the body and it is the final common pathway of various cardiac pathologies. Electrophysiological remodeling, intercellular uncoupling and a pro-fibrotic response have been identified as major arrhythmogenic factors in heart failure. OBJECTIVE In this study we investigate vulnerability to reentry under heart failure conditions by incorporating established electrophysiological and anatomical remodeling using computer simulations. METHODS The electrical activity of human transmural ventricular tissue (5 cm × 5 cm) was simulated using the human ventricular action potential model Grandi et al. under control and heart failure conditions. The MacCannell et al. model was used to model fibroblast electrical activity, and their electrotonic interactions with myocytes. Selected degrees of diffuse fibrosis and variations in intercellular coupling were considered and the vulnerable window (VW) for reentry was evaluated following cross-field stimulation. RESULTS No reentry was observed in normal conditions or in the presence of HF ionic remodeling. However, defined amount of fibrosis and/or cellular uncoupling were sufficient to elicit reentrant activity. Under conditions where reentry was generated, HF electrophysiological remodeling did not alter the width of the VW. However, intermediate fibrosis and cellular uncoupling significantly widened the VW. In addition, biphasic behavior was observed, as very high fibrotic content or very low tissue conductivity hampered the development of reentry. Detailed phase analysis of reentry dynamics revealed an increase of phase singularities with progressive fibrotic components. CONCLUSION Structural remodeling is a key factor in the genesis of vulnerability to reentry. A range of intermediate levels of fibrosis and intercellular uncoupling can combine to favor reentrant activity.
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Affiliation(s)
- Juan F. Gomez
- Instituto de Investigación en Ingeniería Biomédica, UniversitatPolitècnica de València, Valencia, Spain
| | - Karen Cardona
- Instituto de Investigación en Ingeniería Biomédica, UniversitatPolitècnica de València, Valencia, Spain
| | - Laura Martinez
- Instituto de Investigación en Ingeniería Biomédica, UniversitatPolitècnica de València, Valencia, Spain
| | - Javier Saiz
- Instituto de Investigación en Ingeniería Biomédica, UniversitatPolitècnica de València, Valencia, Spain
| | - Beatriz Trenor
- Instituto de Investigación en Ingeniería Biomédica, UniversitatPolitècnica de València, Valencia, Spain
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Veeraraghavan R, Gourdie RG, Poelzing S. Mechanisms of cardiac conduction: a history of revisions. Am J Physiol Heart Circ Physiol 2014; 306:H619-27. [PMID: 24414064 DOI: 10.1152/ajpheart.00760.2013] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac conduction is the process by which electrical excitation spreads through the heart, triggering individual myocytes to contract in synchrony. Defects in conduction disrupt synchronous activation and are associated with life-threatening arrhythmias in many pathologies. Therefore, it is scarcely surprising that this phenomenon continues to be the subject of active scientific inquiry. Here we provide a brief review of how the conceptual understanding of conduction has evolved over the last century and highlight recent, potentially paradigm-shifting developments.
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Affiliation(s)
- Rengasayee Veeraraghavan
- Virginia Tech Carilion Research Institute, and Center for Heart and Regenerative Medicine, Virginia Polytechnic University, Roanoke, Virginia; and
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Trayanova NA, Boyle PM. Advances in modeling ventricular arrhythmias: from mechanisms to the clinic. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2013; 6:209-24. [PMID: 24375958 DOI: 10.1002/wsbm.1256] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 10/16/2013] [Accepted: 11/12/2013] [Indexed: 11/12/2022]
Abstract
Modern cardiovascular research has increasingly recognized that heart models and simulation can help interpret an array of experimental data and dissect important mechanisms and interrelationships, with developments rooted in the iterative interaction between modeling and experimentation. This article reviews the progress made in simulating cardiac electrical behavior at the level of the organ and, specifically, in the development of models of ventricular arrhythmias and fibrillation, as well as their termination (defibrillation). The ability to construct multiscale models of ventricular arrhythmias, representing integrative behavior from the molecule to the entire organ, has enabled mechanistic inquiry into the dynamics of ventricular arrhythmias in the diseased myocardium, in understanding drug-induced proarrhythmia, and in the development of new modalities for defibrillation, to name a few. In this article, we also review the initial use of ventricular models of arrhythmia in personalized diagnosis, treatment planning, and prevention of sudden cardiac death. Implementing individualized cardiac simulations at the patient bedside is poised to become one of the most thrilling examples of computational science and engineering approaches in translational medicine.
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Affiliation(s)
- Natalia A Trayanova
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
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40
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Lajiness JD, Conway SJ. Origin, development, and differentiation of cardiac fibroblasts. J Mol Cell Cardiol 2013; 70:2-8. [PMID: 24231799 DOI: 10.1016/j.yjmcc.2013.11.003] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/23/2013] [Accepted: 11/04/2013] [Indexed: 01/14/2023]
Abstract
Cardiac fibroblasts are the most abundant cell in the mammalian heart. While they have been historically underappreciated in terms of their functional contributions to cardiac development and physiology, they and their activated form, myofibroblasts, are now known to play key roles in both development and disease through structural, paracrine, and electrical interactions with cardiomyocytes. The lack of specific markers for fibroblasts currently convolutes the study of this dynamic cell lineage, but advances in marker analysis and lineage mapping technologies are continuously being made. Understanding how to best utilize these tools, both individually and in combination, will help to elucidate the functional significance of fibroblast-cardiomyocyte interactions in vivo. Here we review what is currently known about the diverse roles played by cardiac fibroblasts and myofibroblasts throughout development and periods of injury with the intent of emphasizing the duality of their nature. This article is part of a Special Issue entitled "Myocyte-Fibroblast Signalling in Myocardium ".
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Affiliation(s)
- Jacquelyn D Lajiness
- Developmental Biology and Neonatal Medicine Program, HB Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Simon J Conway
- Developmental Biology and Neonatal Medicine Program, HB Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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Nayak AR, Shajahan TK, Panfilov AV, Pandit R. Spiral-wave dynamics in a mathematical model of human ventricular tissue with myocytes and fibroblasts. PLoS One 2013; 8:e72950. [PMID: 24023798 PMCID: PMC3762734 DOI: 10.1371/journal.pone.0072950] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 07/15/2013] [Indexed: 11/18/2022] Open
Abstract
Cardiac fibroblasts, when coupled functionally with myocytes, can modulate the electrophysiological properties of cardiac tissue. We present systematic numerical studies of such modulation of electrophysiological properties in mathematical models for (a) single myocyte-fibroblast (MF) units and (b) two-dimensional (2D) arrays of such units; our models build on earlier ones and allow for zero-, one-, and two-sided MF couplings. Our studies of MF units elucidate the dependence of the action-potential (AP) morphology on parameters such as , the fibroblast resting-membrane potential, the fibroblast conductance , and the MF gap-junctional coupling . Furthermore, we find that our MF composite can show autorhythmic and oscillatory behaviors in addition to an excitable response. Our 2D studies use (a) both homogeneous and inhomogeneous distributions of fibroblasts, (b) various ranges for parameters such as , and , and (c) intercellular couplings that can be zero-sided, one-sided, and two-sided connections of fibroblasts with myocytes. We show, in particular, that the plane-wave conduction velocity decreases as a function of , for zero-sided and one-sided couplings; however, for two-sided coupling, decreases initially and then increases as a function of , and, eventually, we observe that conduction failure occurs for low values of . In our homogeneous studies, we find that the rotation speed and stability of a spiral wave can be controlled either by controlling or . Our studies with fibroblast inhomogeneities show that a spiral wave can get anchored to a local fibroblast inhomogeneity. We also study the efficacy of a low-amplitude control scheme, which has been suggested for the control of spiral-wave turbulence in mathematical models for cardiac tissue, in our MF model both with and without heterogeneities.
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Affiliation(s)
- Alok Ranjan Nayak
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore, India
| | - T. K. Shajahan
- Centre for Nonlinear Dynamics in Physiology and Medicine, McGill University, Montreal, Canada
| | - A. V. Panfilov
- Department of Physics and Astronomy, Gent University, Gent, Belgium
| | - Rahul Pandit
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore, India
- Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
- * E-mail:
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42
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Huang W, Dai B, Wen Z, Millard RW, Yu XY, Luther K, Xu M, Zhao TC, Yang HT, Qi Z, LaSance K, Ashraf M, Wang Y. Molecular strategy to reduce in vivo collagen barrier promotes entry of NCX1 positive inducible pluripotent stem cells (iPSC(NCX¹⁺)) into ischemic (or injured) myocardium. PLoS One 2013; 8:e70023. [PMID: 23990893 PMCID: PMC3749126 DOI: 10.1371/journal.pone.0070023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 06/19/2013] [Indexed: 01/28/2023] Open
Abstract
OBJECTIVE The purpose of this study was to assess the effect of collagen composition on engraftment of progenitor cells within infarcted myocardium. BACKGROUND We previously reported that intramyocardial penetration of stem/progenitor cells in epicardial patches was enhanced when collagen was reduced in hearts overexpressing adenylyl cyclase-6 (AC6). In this study we hypothesized an alternative strategy wherein overexpression of microRNA-29b (miR-29b), inhibiting mRNAs that encode cardiac fibroblast proteins involved in fibrosis, would similarly facilitate progenitor cell migration into infarcted rat myocardium. METHODS In vitro: A tri-cell patch (Tri-P) consisting of cardiac sodium-calcium exchanger-1 (NCX1) positive iPSC (iPSC(NCX1+)), endothelial cells (EC), and mouse embryonic fibroblasts (MEF) was created, co-cultured, and seeded on isolated peritoneum. The expression of fibrosis-related genes was analyzed in cardiac fibroblasts (CFb) by qPCR and Western blot. In vivo: Nude rat hearts were administered mimic miRNA-29b (miR-29b), miRNA-29b inhibitor (Anti-29b), or negative mimic (Ctrl) before creation of an ischemically induced regional myocardial infarction (MI). The Tri-P was placed over the infarcted region 7 days later. Angiomyogenesis was analyzed by micro-CT imaging and immunofluorescent staining. Echocardiography was performed weekly. RESULTS The number of green fluorescent protein positive (GFP(+)) cells, capillary density, and heart function were significantly increased in hearts overexpressing miR-29b as compared with Ctrl and Anti-29b groups. Conversely, down-regulation of miR-29b with anti-29b in vitro and in vivo induced interstitial fibrosis and cardiac remodeling. CONCLUSION Overexpression of miR-29b significantly reduced scar formation after MI and facilitated iPSC(NCX1+) penetration from the cell patch into the infarcted area, resulting in restoration of heart function after MI.
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Affiliation(s)
- Wei Huang
- Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
| | - Bo Dai
- Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
| | - Zhili Wen
- Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
- Infectious Disease Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Ronald W. Millard
- Department of Pharmacology and Cell Biophysics, College of Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
| | - Xi-Yong Yu
- Medical Research Center of Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, China
| | - Kristin Luther
- Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
| | - Meifeng Xu
- Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
| | - Ting C. Zhao
- Cardiovascular Laboratories, Department of Surgery, Boston University Medical School, Roger William Medical Center, Providence, Rhode Island, United States of America
| | - Huang-Tian Yang
- Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhihua Qi
- Department of Radiology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Kathleen LaSance
- Department of Radiology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Muhammad Ashraf
- Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
| | - Yigang Wang
- Department of Pathology and Laboratory Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
- * E-mail:
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43
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Excitation-contraction coupling between human atrial myocytes with fibroblasts and stretch activated channel current: a simulation study. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2013; 2013:238676. [PMID: 24000290 PMCID: PMC3755441 DOI: 10.1155/2013/238676] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/13/2013] [Accepted: 07/13/2013] [Indexed: 12/23/2022]
Abstract
Myocytes have been regarded as the main objectives in most cardiac modeling studies and attracted a lot of attention. Connective tissue cells, such as fibroblasts (Fbs), also play crucial role in cardiac function. This study proposed an integrated myocyte-Isac-Fb electromechanical model to investigate the effect of Fbs and stretch activated ion channel current (Isac) on cardiac electrical excitation conduction and mechanical contraction. At the cellular level, an active Fb model was coupled with a human atrial myocyte electrophysiological model (including Isac) and a mechanical model. At the tissue level, electrical excitation conduction was coupled with an elastic mechanical model, in which finite difference method (FDM) was used to solve the electrical excitation equations, while finite element method (FEM) was used for the mechanics equations. The simulation results showed that Fbs and Isac coupling caused diverse effects on action potential morphology during repolarization, depolarized the resting membrane potential of the human atrial myocyte, slowed down wave propagation, and decreased strains in fibrotic tissue. This preliminary simulation study indicates that Fbs and Isac have important implications for modulating cardiac electromechanical behavior and should be considered in future cardiac modeling studies.
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Steinke K, Sachse F, Ettischer N, Strutz‐Seebohm N, Henrion U, Rohrbeck M, Klosowski R, Wolters D, Brunner S, Franz W, Pott L, Munoz C, Kandolf R, Schulze‐Bahr E, Lang F, Klingel K, Seebohm G. Coxsackievirus B3 modulates cardiac ion channels. FASEB J 2013; 27:4108-21. [DOI: 10.1096/fj.13-230193] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Katja Steinke
- Institute for Genetics of Heart Diseases (IfGH)Department of Cardiovascular MedicineUniversity Hospital MünsterMünsterGermany
- Department of Biochemistry ICation Channel GroupRuhr University BochumBochumGermany
| | - Frank Sachse
- Nora Eccles Cardiovascular Research and Training InstituteUniversity of UtahSalt Lake CityUtahUSA
- Department of BioengineeringUniversity of UtahSalt Lake CityUtahUSA
| | - Nicole Ettischer
- Department of Molecular PathologyUniversity Hospital of TuebingenTuebingenGermany
| | - Nathalie Strutz‐Seebohm
- Institute for Genetics of Heart Diseases (IfGH)Department of Cardiovascular MedicineUniversity Hospital MünsterMünsterGermany
| | - Ulrike Henrion
- Institute for Genetics of Heart Diseases (IfGH)Department of Cardiovascular MedicineUniversity Hospital MünsterMünsterGermany
- Department of Physiology IUniversity of TuebingenTuebingenGermany
| | - Matthias Rohrbeck
- Institute for Genetics of Heart Diseases (IfGH)Department of Cardiovascular MedicineUniversity Hospital MünsterMünsterGermany
| | - Rafael Klosowski
- Department of Analytical ChemistryRuhr University BochumBochumGermany
| | - Dirk Wolters
- Department of Analytical ChemistryRuhr University BochumBochumGermany
| | - Stefan Brunner
- Department of Biochemistry ICation Channel GroupRuhr University BochumBochumGermany
| | - Wolfgang‐Michael Franz
- Department of Internal Medicine ILudwig Maximilians UniversityCampus GrosshadernMunichGermany
| | - Lutz Pott
- Department of Cellular PhysiologyRuhr University BochumBochumGermany
| | - Carlos Munoz
- Department of Physiology IUniversity of TuebingenTuebingenGermany
| | - Reinhard Kandolf
- Nora Eccles Cardiovascular Research and Training InstituteUniversity of UtahSalt Lake CityUtahUSA
- Department of BioengineeringUniversity of UtahSalt Lake CityUtahUSA
| | - Eric Schulze‐Bahr
- Institute for Genetics of Heart Diseases (IfGH)Department of Cardiovascular MedicineUniversity Hospital MünsterMünsterGermany
| | - Florian Lang
- Department of Physiology IUniversity of TuebingenTuebingenGermany
| | - Karin Klingel
- Department of Molecular PathologyUniversity Hospital of TuebingenTuebingenGermany
| | - Guiscard Seebohm
- Institute for Genetics of Heart Diseases (IfGH)Department of Cardiovascular MedicineUniversity Hospital MünsterMünsterGermany
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45
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Schwab BC, Seemann G, Lasher RA, Torres NS, Wulfers EM, Arp M, Carruth ED, Bridge JHB, Sachse FB. Quantitative analysis of cardiac tissue including fibroblasts using three-dimensional confocal microscopy and image reconstruction: towards a basis for electrophysiological modeling. IEEE TRANSACTIONS ON MEDICAL IMAGING 2013; 32:862-72. [PMID: 23340590 PMCID: PMC4207629 DOI: 10.1109/tmi.2013.2240693] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Electrophysiological modeling of cardiac tissue is commonly based on functional and structural properties measured in experiments. Our knowledge of these properties is incomplete, in particular their remodeling in disease. Here, we introduce a methodology for quantitative tissue characterization based on fluorescent labeling, 3-D scanning confocal microscopy, image processing and reconstruction of tissue micro-structure at sub-micrometer resolution. We applied this methodology to normal rabbit ventricular tissue and tissue from hearts with myocardial infarction. Our analysis revealed that the volume fraction of fibroblasts increased from 4.83±0.42% (mean ± standard deviation) in normal tissue up to 6.51±0.38% in myocardium from infarcted hearts. The myocyte volume fraction decreased from 76.20±9.89% in normal to 73.48±8.02% adjacent to the infarct. Numerical field calculations on 3-D reconstructions of the extracellular space yielded an extracellular longitudinal conductivity of 0.264±0.082 S/m with an anisotropy ratio of 2.095±1.11 in normal tissue. Adjacent to the infarct, the longitudinal conductivity increased up to 0.400±0.051 S/m, but the anisotropy ratio decreased to 1.295±0.09. Our study indicates an increased density of gap junctions proximal to both fibroblasts and myocytes in infarcted versus normal tissue, supporting previous hypotheses of electrical coupling of fibroblasts and myocytes in infarcted hearts. We suggest that the presented methodology provides an important contribution to modeling normal and diseased tissue. Applications of the methodology include the clinical characterization of disease-associated remodeling.
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Affiliation(s)
- Bettina C Schwab
- Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT 84112, USA.
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46
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Sun GX, Wang LJ, Xiang C, Qin KR. A dynamic model for intracellular calcium response in fibroblasts induced by electrical stimulation. Math Biosci 2013; 244:47-57. [PMID: 23624256 DOI: 10.1016/j.mbs.2013.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 04/13/2013] [Accepted: 04/15/2013] [Indexed: 11/27/2022]
Abstract
Regulation of intracellular calcium ion concentration ([Ca(2+)]in) in fibroblasts induced by exogenous electrical stimulation could be applied to control gene expressions selectively which in turn modulate the function of the fibroblasts. Regarding the mechanism for electric-field-induced Ca(2+) influx via voltage-gated Ca(2+) channels and/or stretch-activated cation channels in the fibroblasts, a dynamic mathematical model is proposed to quantify the [Ca(2+)]in dynamics in response to direct current or alternating current electric fields. Simulation results demonstrate that the changes in [Ca(2+)]in predicted by our dynamic model are consistent with the experimental data in the literature. The proposed dynamic model could provide not only more insights into the electric-field-induced intracellular Ca(2+) response but also a quantitative way to regulate the [Ca(2+)]in dynamics by controlling the external electrical stimulation.
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Affiliation(s)
- Guo-Xin Sun
- Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, No. 2, Linggong Rd., Dalian 116024, China
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47
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Zhang P, Su J, Mende U. Cross talk between cardiac myocytes and fibroblasts: from multiscale investigative approaches to mechanisms and functional consequences. Am J Physiol Heart Circ Physiol 2012; 303:H1385-96. [PMID: 23064834 DOI: 10.1152/ajpheart.01167.2011] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The heart is comprised of a syncytium of cardiac myocytes (CM) and surrounding nonmyocytes, the majority of which are cardiac fibroblasts (CF). CM and CF are highly interspersed in the myocardium with one CM being surrounded by one or more CF. Bidirectional cross talk between CM and CF plays important roles in determining cardiac mechanical and electrical function in both normal and diseased hearts. Genetically engineered animal models and in vitro studies have provided evidence that CM and CF can regulate each other's function. Their cross talk contributes to structural and electrical remodeling in both atria and ventricles and appears to be involved in the pathogenesis of various heart diseases that lead to heart failure and arrhythmia disorders. Mechanisms of CM-CF cross talk, which are not yet fully understood, include release of paracrine factors, direct cell-cell interactions via gap junctions and potentially adherens junctions and nanotubes, and cell interactions with the extracellular matrix. In this article, we provide an overview of the existing multiscale experimental and computational approaches for the investigation of cross talk between CM and CF and review recent progress in our understanding of the functional consequences and underlying mechanisms. Targeting cross talk between CM and CF could potentially be used therapeutically for the modulation of the cardiac remodeling response in the diseased heart and may lead to new strategies for the treatment of heart failure or rhythm disturbances.
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Affiliation(s)
- P Zhang
- Cardiovascular Research Center, Cardiology Division, Rhode Island Hospital, Providence, USA
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48
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Hwang HJ, Chang W, Song BW, Song H, Cha MJ, Kim IK, Lim S, Choi EJ, Ham O, Lee SY, Shim J, Joung B, Pak HN, Kim SS, Choi BR, Jang Y, Lee MH, Hwang KC. Antiarrhythmic Potential of Mesenchymal Stem Cell Is Modulated by Hypoxic Environment. J Am Coll Cardiol 2012; 60:1698-706. [DOI: 10.1016/j.jacc.2012.04.056] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 04/11/2012] [Accepted: 04/24/2012] [Indexed: 10/27/2022]
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Modeling to link regional myocardial work, metabolism and blood flows. Ann Biomed Eng 2012; 40:2379-98. [PMID: 22915334 DOI: 10.1007/s10439-012-0613-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 06/21/2012] [Indexed: 12/13/2022]
Abstract
Given the mono-functional, highly coordinated processes of cardiac excitation and contraction, the observations that regional myocardial blood flows, rMBF, are broadly heterogeneous has provoked much attention, but a clear explanation has not emerged. In isolated and in vivo heart studies the total coronary flow is found to be proportional to the rate-pressure product (systolic mean blood pressure times heart rate), a measure of external cardiac work. The same relationship might be expected on a local basis: more work requires more flow. The validity of this expectation has never been demonstrated experimentally. In this article we review the concepts linking cellular excitation and contractile work to cellular energetics and ATP demand, substrate utilization, oxygen demand, vasoregulation, and local blood flow. Mathematical models of these processes are now rather well developed. We propose that the construction of an integrated model encompassing the biophysics, biochemistry and physiology of cardiomyocyte contraction, then combined with a detailed three-dimensional structuring of the fiber bundle and sheet arrangements of the heart as a whole will frame an hypothesis that can be quantitatively evaluated to settle the prime issue: Does local work drive local flow in a predictable fashion that explains the heterogeneity? While in one sense one can feel content that work drives flow is irrefutable, the are no cardiac contractile models that demonstrate the required heterogeneity in local strain-stress-work; quite the contrary, cardiac contraction models have tended toward trying to show that work should be uniform. The object of this review is to argue that uniformity of work does not occur, and is impossible in any case, and that further experimentation and analysis are necessary to test the hypothesis.
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Roberts BN, Yang PC, Behrens SB, Moreno JD, Clancy CE. Computational approaches to understand cardiac electrophysiology and arrhythmias. Am J Physiol Heart Circ Physiol 2012; 303:H766-83. [PMID: 22886409 DOI: 10.1152/ajpheart.01081.2011] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Cardiac rhythms arise from electrical activity generated by precisely timed opening and closing of ion channels in individual cardiac myocytes. These impulses spread throughout the cardiac muscle to manifest as electrical waves in the whole heart. Regularity of electrical waves is critically important since they signal the heart muscle to contract, driving the primary function of the heart to act as a pump and deliver blood to the brain and vital organs. When electrical activity goes awry during a cardiac arrhythmia, the pump does not function, the brain does not receive oxygenated blood, and death ensues. For more than 50 years, mathematically based models of cardiac electrical activity have been used to improve understanding of basic mechanisms of normal and abnormal cardiac electrical function. Computer-based modeling approaches to understand cardiac activity are uniquely helpful because they allow for distillation of complex emergent behaviors into the key contributing components underlying them. Here we review the latest advances and novel concepts in the field as they relate to understanding the complex interplay between electrical, mechanical, structural, and genetic mechanisms during arrhythmia development at the level of ion channels, cells, and tissues. We also discuss the latest computational approaches to guiding arrhythmia therapy.
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Affiliation(s)
- Byron N Roberts
- Tri-Institutional MD-PhD Program, Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Medical College/The Rockefeller University/Sloan-Kettering Cancer Institute, Weill Medical College of Cornell University, New York, New York, USA
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