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Kofron CM, Kim TY, King ME, Xie A, Feng F, Park E, Qu Z, Choi BR, Mende U. G q-activated fibroblasts induce cardiomyocyte action potential prolongation and automaticity in a three-dimensional microtissue environment. Am J Physiol Heart Circ Physiol 2017; 313:H810-H827. [PMID: 28710068 DOI: 10.1152/ajpheart.00181.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 06/13/2017] [Accepted: 07/03/2017] [Indexed: 11/22/2022]
Abstract
Cardiac fibroblasts (CFs) are known to regulate cardiomyocyte (CM) function in vivo and in two-dimensional in vitro cultures. This study examined the effect of CF activation on the regulation of CM electrical activity in a three-dimensional (3-D) microtissue environment. Using a scaffold-free 3-D platform with interspersed neonatal rat ventricular CMs and CFs, Gq-mediated signaling was selectively enhanced in CFs by Gαq adenoviral infection before coseeding with CMs in nonadhesive hydrogels. After 3 days, the microtissues were analyzed by signaling assay, histological staining, quantitative PCR, Western blots, optical mapping with voltage- or Ca2+-sensitive dyes, and microelectrode recordings of CF resting membrane potential (RMPCF). Enhanced Gq signaling in CFs increased microtissue size and profibrotic and prohypertrophic markers. Expression of constitutively active Gαq in CFs prolonged CM action potential duration (by 33%) and rise time (by 31%), prolonged Ca2+ transient duration (by 98%) and rise time (by 65%), and caused abnormal electrical activity based on depolarization-induced automaticity. Constitutive Gq activation in CFs also depolarized RMPCF from -33 to -20 mV and increased connexin 43 and connexin 45 expression. Computational modeling confers that elevated RMPCF and increased cell-cell coupling between CMs and CFs in a 3-D environment could lead to automaticity. In conclusion, our data demonstrate that CF activation alone is capable of altering action potential and Ca2+ transient characteristics of CMs, leading to proarrhythmic electrical activity. Our results also emphasize the importance of a 3-D environment where cell-cell interactions are prevalent, underscoring that CF activation in 3-D tissue plays a significant role in modulating CM electrophysiology and arrhythmias.NEW & NOTEWORTHY In a three-dimensional microtissue model, which lowers baseline activation of cardiac fibroblasts but enables cell-cell, paracrine, and cell-extracellular matrix interactions, we demonstrate that selective cardiac fibroblast activation by enhanced Gq signaling, a pathophysiological trigger in the diseased heart, modulates cardiomyocyte electrical activity, leading to proarrhythmogenic automaticity.
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Affiliation(s)
- C M Kofron
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - T Y Kim
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - M E King
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - A Xie
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - F Feng
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - E Park
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - Z Qu
- Department of Medicine, University of California, Los Angeles, California
| | - B-R Choi
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
| | - U Mende
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, Rhode Island; and
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Cosme J, Guo H, Hadipour-Lakmehsari S, Emili A, Gramolini AO. Hypoxia-Induced Changes in the Fibroblast Secretome, Exosome, and Whole-Cell Proteome Using Cultured, Cardiac-Derived Cells Isolated from Neonatal Mice. J Proteome Res 2017. [PMID: 28641008 DOI: 10.1021/acs.jproteome.7b00144] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cardiac fibroblasts (CFs) represent a major subpopulation of cells in the developing and adult heart. Cardiomyocyte (CM) and CF intercellular communication occurs through paracrine interactions and modulate myocyte development and stress response. Detailed proteomic analysis of the CF secretome in normal and stressed conditions may offer insights into the role of CF in heart development and disease. Primary neonatal mouse CFs were isolated and cultured for 24 h in 21% (normoxic) or 2% (hypoxic) O2. Conditioned medium was separated to obtain exosomes (EXO) and EXO-depleted secretome fractions. Multidimensional protein identification technology was performed on secreted fractions. Whole cell lysate data were also generated to provide subcellular context to the secretome. Proteomic analysis identified 6163 unique proteins in total. Statistical (QSpec) analysis identified 494 proteins differentially expressed between fractions and oxygen conditions. Gene Ontology enrichment analysis revealed hypoxic conditions selectively increase expression of proteins with extracellular matrix and signaling annotations. Finally, we subjected CM pretreated with CF secreted factors to hypoxia/reoxygenation. Viability assays suggested altered viability due to CF-derived factors. CF secretome proteomics revealed differential expression based on mode of secretion and oxygen levels in vitro.
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Affiliation(s)
- Jake Cosme
- Department of Physiology and Translational Biology and Engineering Program (TBEP), University of Toronto , Toronto, Ontario M5G 1M1, Canada
| | - Hongbo Guo
- The Donnelly Centre for Cellular and Biomolecular Research, Ted Rogers Centre for Heart Research, University of Toronto , Toronto, Ontario M5S 3E1, Canada
| | - Sina Hadipour-Lakmehsari
- Department of Physiology and Translational Biology and Engineering Program (TBEP), University of Toronto , Toronto, Ontario M5G 1M1, Canada
| | - Andrew Emili
- The Donnelly Centre for Cellular and Biomolecular Research, Ted Rogers Centre for Heart Research, University of Toronto , Toronto, Ontario M5S 3E1, Canada
| | - Anthony O Gramolini
- Department of Physiology and Translational Biology and Engineering Program (TBEP), University of Toronto , Toronto, Ontario M5G 1M1, Canada
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Affiliation(s)
- Yoshinori Yoshida
- From the Center for iPS Cell Research and Application, Kyoto University, Japan (Y.Y., S.Y.); and Gladstone Institute of Cardiovascular Disease, Gladstone Institutes, San Francisco, CA (S.Y.)
| | - Shinya Yamanaka
- From the Center for iPS Cell Research and Application, Kyoto University, Japan (Y.Y., S.Y.); and Gladstone Institute of Cardiovascular Disease, Gladstone Institutes, San Francisco, CA (S.Y.)
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Li Y, Asfour H, Bursac N. Age-dependent functional crosstalk between cardiac fibroblasts and cardiomyocytes in a 3D engineered cardiac tissue. Acta Biomater 2017; 55:120-130. [PMID: 28455218 DOI: 10.1016/j.actbio.2017.04.027] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 04/18/2017] [Accepted: 04/24/2017] [Indexed: 10/19/2022]
Abstract
Complex heterocellular interactions between cardiomyocytes and fibroblasts in the heart involve their bidirectional signaling via cell-cell contacts, paracrine factors, and extracellular matrix (ECM). These interactions vary with heart development and pathology leading to changes in cardiac structure and function. Whether cardiac fibroblasts of different ages interact differentially with cardiomyocytes to distinctly impact their function remains unknown. Here, we explored the direct structural and functional effects of fetal and adult cardiac fibroblasts on cardiomyocytes using a tissue-engineered 3D co-culture system. We show that the age of cardiac fibroblasts is a strong determinant of the structure, function, and molecular properties of co-cultured tissues. In particular, in vitro expanded adult, but not fetal, cardiac fibroblasts significantly deteriorated electrical and mechanical function of the co-cultured cardiomyocytes, as evidenced by slower action potential conduction, prolonged action potential duration, weaker contractions, higher tissue stiffness, and reduced calcium transient amplitude. This functional deficit was associated with structural and molecular signatures of pathological remodeling including fibroblast proliferation, interstitial collagen deposition, and upregulation of pro-fibrotic markers. Our studies imply critical roles of the age of supporting cells in engineering functional cardiac tissues and provide a new physiologically relevant in vitro platform to investigate influence of heterocellular interactions on cardiomyocyte function, development, and disease. STATEMENT OF SIGNIFICANCE Previous studies have shown that cardiomyocytes and fibroblasts in the heart interact through direct contacts, paracrine factors, and matrix-mediated crosstalk. However, whether cardiac fibroblasts of different ages distinctly impact cardiomyocyte function remains elusive. We employed a tissue-engineered hydrogel-based co-culture system to study interactions of cardiomyocytes with fetal or adult cardiac fibroblasts. We show that the age of cardiac fibroblasts is a strong determinant of the structure, function, and molecular properties of engineered cardiac tissues and that key features of fibrotic myocardium are replicated by supplementing cardiomyocytes with expanded adult but not fetal fibroblasts. These findings relate to implantation of stem cell-derived cardiomyocytes in adult myocardium and warrant further studies of how age and source of non-myocytes impact cardiac function and maturation.
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Liau B, Jackman CP, Li Y, Bursac N. Developmental stage-dependent effects of cardiac fibroblasts on function of stem cell-derived engineered cardiac tissues. Sci Rep 2017; 7:42290. [PMID: 28181589 PMCID: PMC5299411 DOI: 10.1038/srep42290] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 01/09/2017] [Indexed: 12/31/2022] Open
Abstract
We investigated whether the developmental stage of mouse cardiac fibroblasts (CFs) influences the formation and function of engineered cardiac tissues made of mouse embryonic stem cell-derived cardiomyocytes (mESC-CMs). Engineered cardiac tissue patches were fabricated by encapsulating pure mESC-CMs, mESC-CMs + adult CFs, or mESC-CMs + fetal CFs in fibrin-based hydrogel. Tissue patches containing fetal CFs exhibited higher velocity of action potential propagation and contractile force amplitude compared to patches containing adult CFs, while pure mESC-CM patches did not form functional syncytium. The functional improvements in mESC-CM + fetal CF patches were associated with differences in structural remodeling and increased expression of proteins involved in cardiac function. To determine role of paracrine signaling, we cultured pure mESC-CMs within miniature tissue "micro-patches" supplemented with media conditioned by adult or fetal CFs. Fetal CF-conditioned media distinctly enhanced CM spreading and contractile activity, which was shown by pathway inhibitor experiments and Western blot analysis to be mediated via MEK-ERK signaling. In mESC-CM monolayers, CF-conditioned media did not alter CM spreading or MEK-ERK activation. Collectively, our studies show that 3D co-culture of mESC-CMs with embryonic CFs is superior to co-culture with adult CFs for in vitro generation of functional myocardium. Ensuring consistent developmental stages of cardiomyocytes and supporting non-myocytes may be a critical factor for promoting functional maturation of engineered cardiac tissues.
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Affiliation(s)
- Brian Liau
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | | | - Yanzhen Li
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Nenad Bursac
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
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Begg GA, Holden AV, Lip GY, Plein S, Tayebjee MH. Assessment of atrial fibrosis for the rhythm control of atrial fibrillation. Int J Cardiol 2016; 220:155-61. [DOI: 10.1016/j.ijcard.2016.06.144] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 06/11/2016] [Accepted: 06/24/2016] [Indexed: 01/26/2023]
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ten Sande JN, Smit NW, Parvizi M, van Amersfoorth SC, Plantinga JA, van Dessel PF, de Bakker JM, Harmsen MC, Coronel R. Differential Mechanisms of Myocardial Conduction Slowing by Adipose Tissue-Derived Stromal Cells Derived from Different Species. Stem Cells Transl Med 2016; 6:22-30. [PMID: 28170198 PMCID: PMC5442737 DOI: 10.5966/sctm.2015-0415] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 06/22/2016] [Indexed: 11/18/2022] Open
Abstract
Stem cell therapy is a promising therapeutic option to treat patients after myocardial infarction. However, the intramyocardial administration of large amounts of stem cells might generate a proarrhythmic substrate. Proarrhythmic effects can be explained by electrotonic and/or paracrine mechanisms. The narrow therapeutic time window for cell therapy and the presence of comorbidities limit the application of autologous cell therapy. The use of allogeneic or xenogeneic stem cells is a potential alternative to autologous cells, but differences in the proarrhythmic effects of adipose‐derived stromal cells (ADSCs) across species are unknown. Using microelectrode arrays and microelectrode recordings, we obtained local unipolar electrograms and action potentials from monolayers of neonatal rat ventricular myocytes (NRVMs) that were cocultured with rat, human, or pig ADSCs (rADSCs, hADSCs, pADSCs, respectively). Monolayers of NRVMs were cultured in the respective conditioned medium to investigate paracrine effects. We observed significant conduction slowing in all cardiomyocyte cultures containing ADSCs, independent of species used (p < .01). All cocultures were depolarized compared with controls (p < .01). Only conditioned medium taken from cocultures with pADSCs and applied to NRVM monolayers demonstrated similar electrophysiological changes as the corresponding cocultures. We have shown that independent of species used, ADSCs cause conduction slowing in monolayers of NRVMs. In addition, pADSCs exert conduction slowing mainly by a paracrine effect, whereas the influence on conduction by hADSCs and rADSCs is preferentially by electrotonic interaction. Stem Cells Translational Medicine2017;6:22–30
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Affiliation(s)
- Judith N. ten Sande
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- Interuniversity Cardiology Institute of the Netherlands, Netherlands Heart Institute, Utrecht, The Netherlands
| | - Nicoline W. Smit
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- Interuniversity Cardiology Institute of the Netherlands, Netherlands Heart Institute, Utrecht, The Netherlands
| | - Mojtaba Parvizi
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, The Netherlands
| | - Shirley C.M. van Amersfoorth
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Josée A. Plantinga
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, The Netherlands
| | - Pascal F.H.M. van Dessel
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Jacques M.T. de Bakker
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- Interuniversity Cardiology Institute of the Netherlands, Netherlands Heart Institute, Utrecht, The Netherlands
| | - Marco C. Harmsen
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, The Netherlands
| | - Ruben Coronel
- Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- L'Institut de Rythmologie et de Modélisation Cardiaque, Université Bordeaux, Segalen, Bordeaux, France
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58
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Dewey CM, Spitler KM, Ponce JM, Hall DD, Grueter CE. Cardiac-Secreted Factors as Peripheral Metabolic Regulators and Potential Disease Biomarkers. J Am Heart Assoc 2016; 5:e003101. [PMID: 27247337 PMCID: PMC4937259 DOI: 10.1161/jaha.115.003101] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Colleen M Dewey
- Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA
| | - Kathryn M Spitler
- Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA
| | - Jessica M Ponce
- Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA
| | - Duane D Hall
- Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA
| | - Chad E Grueter
- Division of Cardiovascular Medicine, Department of Internal Medicine and François M. Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA Fraternal Order of Eagles Diabetes Research Center, Papajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
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59
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Mesenchymal stem cells suppress cardiac alternans by activation of PI3K mediated nitroso-redox pathway. J Mol Cell Cardiol 2016; 98:138-45. [PMID: 27238412 DOI: 10.1016/j.yjmcc.2016.05.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 05/03/2016] [Accepted: 05/25/2016] [Indexed: 01/06/2023]
Abstract
BACKGROUND The paracrine action of non-cardiac progenitor cells is robust, but not well understood. Mesenchymal stem cells (MSC) have been shown to enhance calcium (Ca(++)) cycling in myocytes. Therefore, we hypothesized that MSCs can suppress cardiac alternans, an important arrhythmia substrate, by paracrine action on Ca(++) cycling. METHODS AND RESULTS Human cardiac myocyte monolayers derived from iPS cells (hCM) were cultured without or with human MSCs (hMSC) directly or plated on a transwell insert. Ca(++) transient alternans (Ca(++) ALT) and Ca(++) transient duration (CaD) were measured from hCM monolayers following application of 200μM H2O2. Ca(++) ALT in hCM was significantly decreased when cultured with hMSCs directly (97%, p<0.0001) and when cultured with hMSC in the transwell insert (80%, p<0.0001). When hCM with hMSCs were pretreated with PI3K or eNOS inhibitors, Ca(++) ALT was larger than baseline by 20% (p<0.0001) and 36% (p<0.0001), respectively. In contrast, Ca(++) ALT was reduced by 89% compared to baseline (p<0.0001) when hCM monolayers without hMSCs were pretreated with 20μM GSNO. In all experiments, changes in Ca(++) ALT were mirrored by changes in CaD. Finally, real time quantitative PCR revealed no significant differences in mRNA expression of RyR2, SERCA2a, and phospholamban between hCM cultured with or without hMSCs. CONCLUSION Ca(++) ALT is suppressed by hMSCs in a paracrine fashion due to activation of a PI3K-mediated nitroso-redox pathway. These findings demonstrate, for the first time, how stem cell therapy might be antiarrhythmic by suppressing cardiac alternans through paracrine action on Ca(++) cycling.
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Zahid S, Cochet H, Boyle PM, Schwarz EL, Whyte KN, Vigmond EJ, Dubois R, Hocini M, Haïssaguerre M, Jaïs P, Trayanova NA. Patient-derived models link re-entrant driver localization in atrial fibrillation to fibrosis spatial pattern. Cardiovasc Res 2016; 110:443-54. [PMID: 27056895 DOI: 10.1093/cvr/cvw073] [Citation(s) in RCA: 193] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 03/31/2016] [Indexed: 12/19/2022] Open
Abstract
AIMS The mechanisms underlying persistent atrial fibrillation (AF) in patients with atrial fibrosis are poorly understood. The goal of this study was to use patient-derived atrial models to test the hypothesis that AF re-entrant drivers (RDs) persist only in regions with specific fibrosis patterns. METHODS AND RESULTS Twenty patients with persistent AF (PsAF) underwent late gadolinium-enhanced MRI to detect the presence of atrial fibrosis. Segmented images were used to construct personalized 3D models of the fibrotic atria with biophysically realistic atrial electrophysiology. In each model, rapid pacing was applied to induce AF. AF dynamics were analysed and RDs were identified using phase mapping. Fibrosis patterns in RD regions were characterized by computing maps of fibrosis density (FD) and entropy (FE). AF was inducible in 13/20 models and perpetuated by few RDs (2.7 ± 1.5) that were spatially confined (trajectory of phase singularities: 7.6 ± 2.3 mm). Compared with the remaining atrial tissue, regions where RDs persisted had higher FE (IQR: 0.42-0.60 vs. 0.00-0.40, P < 0.05) and FD (IQR: 0.59-0.77 vs. 0.00-0.33, P < 0.05). Machine learning classified RD and non-RD regions based on FD and FE and identified a subset of fibrotic boundary zones present in 13.8 ± 4.9% of atrial tissue where 83.5 ± 2.4% of all RD phase singularities were located. CONCLUSION Patient-derived models demonstrate that AF in fibrotic substrates is perpetuated by RDs persisting in fibrosis boundary zones characterized by specific regional fibrosis metrics (high FE and FD). These results provide new insights into the mechanisms that sustain PsAF and could pave the way for personalized, MRI-based management of PsAF.
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Affiliation(s)
- Sohail Zahid
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Hubert Cochet
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, INSERM U1045, Bordeaux, France Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université de Bordeaux, Bordeaux, France
| | - Patrick M Boyle
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Erica L Schwarz
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Kaitlyn N Whyte
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Edward J Vigmond
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, INSERM U1045, Bordeaux, France
| | - Rémi Dubois
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, INSERM U1045, Bordeaux, France
| | - Mélèze Hocini
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, INSERM U1045, Bordeaux, France Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université de Bordeaux, Bordeaux, France
| | - Michel Haïssaguerre
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, INSERM U1045, Bordeaux, France Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université de Bordeaux, Bordeaux, France
| | - Pierre Jaïs
- IHU LIRYC, Electrophysiology and Heart Modeling Institute, INSERM U1045, Bordeaux, France Hôpital Cardiologique du Haut-Lévêque, CHU Bordeaux, Université de Bordeaux, Bordeaux, France
| | - Natalia A Trayanova
- Institute for Computational Medicine, Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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The Interaction between Adult Cardiac Fibroblasts and Embryonic Stem Cell-Derived Cardiomyocytes Leads to Proarrhythmic Changes in In Vitro Cocultures. Stem Cells Int 2016; 2016:2936126. [PMID: 26880949 PMCID: PMC4736407 DOI: 10.1155/2016/2936126] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 11/16/2015] [Accepted: 12/14/2015] [Indexed: 01/14/2023] Open
Abstract
Transplantation of stem cell-derived cardiomyocytes is one of the most promising therapeutic approaches after myocardial infarction, as loss of cardiomyocytes is virtually irreversible by endogenous repair mechanisms. In myocardial scars, transplanted cardiomyocytes will be in immediate contact with cardiac fibroblasts. While it is well documented how the electrophysiology of neonatal cardiomyocytes is modulated by cardiac fibroblasts of the same developmental stage, it is unknown how adult cardiac fibroblasts (aCFs) affect the function of embryonic stem cell-derived cardiomyocytes (ESC-CMs). To investigate the effects of aCFs on ESC-CM electrophysiology, we performed extra- and intracellular recordings of murine aCF-ESC-CM cocultures. We observed that spontaneous beating behaviour was highly irregular in aCF-ESC-CM cocultures compared to cocultures with mesenchymal stem cells (coefficient of variation of the interspike interval: 40.5 ± 15.2% versus 9.3 ± 2.0%, p = 0.008) and that action potential amplitude and maximal upstroke velocity (V max) were reduced (amplitude: 52.3 ± 1.7 mV versus 65.1 ± 1.5 mV, V max: 7.0 ± 1.0 V/s versus 36.5 ± 5.3 V/s), while action potential duration (APD) was prolonged (APD50: 25.6 ± 1.0 ms versus 16.8 ± 1.9 ms, p < 0.001; APD90: 52.2 ± 1.5 ms versus 43.3 ± 3.3 ms, p < 0.01) compared to controls. Similar changes could be induced by aCF-conditioned medium. We conclude that the presence of aCFs changes automaticity and induces potentially proarrhythmic changes of ESC-CM electrophysiology.
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Inscribing Optical Excitability to Non-Excitable Cardiac Cells: Viral Delivery of Optogenetic Tools in Primary Cardiac Fibroblasts. Methods Mol Biol 2016; 1408:303-17. [PMID: 26965132 DOI: 10.1007/978-1-4939-3512-3_21] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
We describe in detail a method to introduce optogenetic actuation tools, a mutant version of channelrhodopsin-2, ChR2(H134R), and archaerhodopsin (ArchT), into primary cardiac fibroblasts (cFB) in vitro by adenoviral infection to yield quick, robust, and consistent expression. Instructions on adjusting infection parameters such as the multiplicity of infection and virus incubation duration are provided to generalize the method for different lab settings or cell types. Specific conditions are discussed to create hybrid co-cultures of the optogenetically modified cFB and non-transformed cardiomyocytes to obtain light-sensitive excitable cardiac syncytium, including stencil-patterned cell growth. We also describe an all-optical framework for the functional testing of responsiveness of these opsins in cFB. The presented methodology provides cell-specific tools for the mechanistic investigation of the functional bioelectric contribution of different non-excitable cells in the heart and their electrical coupling to cardiomyocytes under different conditions.
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Mahoney VM, Mezzano V, Morley GE. A review of the literature on cardiac electrical activity between fibroblasts and myocytes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:128-33. [PMID: 26713556 DOI: 10.1016/j.pbiomolbio.2015.12.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/12/2015] [Accepted: 12/16/2015] [Indexed: 12/13/2022]
Abstract
Myocardial injuries often lead to fibrotic deposition. This review presents evidence supporting the concept that fibroblasts in the heart electrically couple to myocytes.
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Affiliation(s)
- Vanessa M Mahoney
- Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Valeria Mezzano
- Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Gregory E Morley
- Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA.
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Yang PC, Song Y, Giles WR, Horvath B, Chen-Izu Y, Belardinelli L, Rajamani S, Clancy CE. A computational modelling approach combined with cellular electrophysiology data provides insights into the therapeutic benefit of targeting the late Na+ current. J Physiol 2015; 593:1429-42. [PMID: 25545172 DOI: 10.1113/jphysiol.2014.279554] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 12/18/2014] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS The ventricular action potential plateau is a phase of high resistance, which makes ventricular myocytes vulnerable to small electrical perturbations. We developed a computationally based model of GS-458967 interaction with the cardiac Na+ channel, informed by experimental data recorded from guinea pig isolated single ventricular myocytes. The model predicts that the therapeutic potential of GS-458967 derives largely from the designed property of significant potent selectivity for INaL. ABSTRACT Selective inhibition of the slowly inactivating or late Na(+) current (INaL) in patients with inherited or acquired arrhythmia syndrome may confer therapeutic benefit by reducing the incidence of triggers for arrhythmia and suppressing one component of arrhythmia-promoting cardiac substrates (e.g. prolonged refractoriness and spatiotemporal dispersion of action potential duration). Recently, a novel compound that preferentially and potently reduces INaL, GS-458967 (IC50 for block of INaL = 130 nM) has been studied. Experimental measurements of the effects of GS-458967 on endogenous INaL in guinea pig ventricular myocytes demonstrate a robust concentration-dependent reduction in action potential duration (APD). Using experimental data to calibrate INaL and the rapidly activating delayed rectifier K(+) current, IKr, in the Faber-Rudy computationally based model of the guinea pig ventricular action potential, we simulated effects of GS-458967 on guinea pig ventricular APD. GS-458967 (0.1 μM) caused a 28.67% block of INaL and 12.57% APD shortening in experiments, while the model predicted 10.06% APD shortening with 29.33% block of INaL. An additional effect of INaL block is to reduce the time during which the membrane potential is in a high resistance state (i.e. the action potential plateau). To test the hypothesis that targeted block of INaL would make ventricular myocytes less susceptible to small electrical perturbations, we used the computational model to test the degree of APD prolongation induced by small electrical perturbations in normal cells and in cells with simulated long QT syndrome. The model predicted a substantial dose-dependent reduction in sensitivity to small electrical perturbations as evidenced by action potential duration at 90% repolarization variability in the presence of GS-458967-induced INaL block. This effect was especially potent in the 'disease setting' of inherited long QT syndrome. Using a combined experimental and theoretical approach, our results suggest that INaL block is a potent therapeutic strategy. This is because reduction of INaL stabilizes the action potential waveform by reducing depolarizing current during the plateau phase of the action potential. This reduces the most vulnerable phase of the action potential with high membrane resistance. In summary, by reducing the sensitivity of the myocardial substrate to small electrical perturbations that promote arrhythmia triggers, agents such as GS-458967 may constitute an effective antiarrhythmic pharmacological strategy.
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Shadrin IY, Yoon W, Li L, Shepherd N, Bursac N. Rapid fusion between mesenchymal stem cells and cardiomyocytes yields electrically active, non-contractile hybrid cells. Sci Rep 2015; 5:12043. [PMID: 26159124 PMCID: PMC4498233 DOI: 10.1038/srep12043] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 06/12/2015] [Indexed: 12/26/2022] Open
Abstract
Cardiac cell therapies involving bone marrow-derived human mesenchymal stem cells (hMSCs) have shown promising results, although their mechanisms of action are still poorly understood. Here, we investigated direct interactions between hMSCs and cardiomyocytes in vitro. Using a genetic Ca2+ indicator gCaMP3 to efficiently label hMSCs in co-cultures with neonatal rat ventricular myocytes (NRVMs), we determined that 25–40% of hMSCs (from 4 independent donors) acquired periodic Ca2+ transients and cardiac markers through spontaneous fusion with NRVMs. Sharp electrode and voltage-clamp recordings in fused cells showed action potential properties and Ca2+ current amplitudes in between those of non-fused hMSCs and NRVMs. Time-lapse video-microscopy revealed the first direct evidence of active fusion between hMSCs and NRVMs within several hours of co-culture. Application of blebbistatin, nifedipine or verapamil caused complete and reversible inhibition of fusion, suggesting potential roles for actomyosin bridging and Ca2+ channels in the fusion process. Immunostaining for Cx43, Ki67, and sarcomeric α-actinin showed that fused cells remain strongly coupled to surrounding NRVMs, but downregulate sarcomeric structures over time, acquiring a non-proliferative and non-contractile phenotype. Overall, these results describe the phenotype and mechanisms of hybrid cell formation via fusion of hMSCs and cardiomyocytes with potential implications for cardiac cell therapy.
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Affiliation(s)
- Ilya Y Shadrin
- Department of Biomedical Engineering, Duke University, Durham, NC
| | - Woohyun Yoon
- Department of Biomedical Engineering, Duke University, Durham, NC
| | - Liqing Li
- Department of Biomedical Engineering, Duke University, Durham, NC
| | - Neal Shepherd
- Department of Biomedical Engineering, Duke University, Durham, NC
| | - Nenad Bursac
- Department of Biomedical Engineering, Duke University, Durham, NC
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Engels MC, Askar SFA, Jangsangthong W, Bingen BO, Feola I, Liu J, Majumder R, Versteegh MIM, Braun J, Klautz RJM, Ypey DL, De Vries AAF, Pijnappels DA. Forced fusion of human ventricular scar cells with cardiomyocytes suppresses arrhythmogenicity in a co-culture model. Cardiovasc Res 2015; 107:601-12. [PMID: 26142215 DOI: 10.1093/cvr/cvv191] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 06/26/2015] [Indexed: 11/14/2022] Open
Abstract
AIMS Fibrosis increases arrhythmogenicity in myocardial tissue by causing structural and functional disruptions in the cardiac syncytium. Forced fusion of fibroblastic cells with adjacent cardiomyocytes may theoretically resolve these disruptions. Therefore, the electrophysiological effects of such electrical and structural integration of fibroblastic cells into a cardiac syncytium were studied. METHODS AND RESULTS Human ventricular scar cells (hVSCs) were transduced with lentiviral vectors encoding enhanced green fluorescent protein alone (eGFP↑-hVSCs) or together with the fusogenic vesicular stomatitis virus G protein (VSV-G/eGFP↑-hVSCs) and subsequently co-cultured (1:4 ratio) with neonatal rat ventricular cardiomyocytes (NRVMs) in confluent monolayers yielding eGFP↑- and VSV-G/eGFP↑-co-cultures, respectively. Cellular fusion was induced by brief exposure to pH = 6.0 medium. Optical mapping experiments showed eGFP↑-co-cultures to be highly arrhythmogenic [43.3% early afterdepolarization (EAD) incidence vs. 7.7% in control NRVM cultures, P < 0.0001], with heterogeneous prolongation of action potential (AP) duration (APD). Fused VSV-G/eGFP↑-co-cultures displayed markedly lower EAD incidence (4.6%, P < 0.001) than unfused co-cultures, associated with decreases in APD, APD dispersion, and decay time of cytosolic Ca(2+) waves. Heterokaryons strongly expressed connexin43 (Cx43). Also, maximum diastolic potential in co-cultures was more negative after fusion, while heterokaryons exhibited diverse mixed NRVM/hVSC whole-cell current profiles, but consistently showed increased outward Kv currents compared with NRVMs or hVSCs. Inhibition of Kv channels by tetraethylammonium chloride abrogated the anti-arrhythmic effects of fusion in VSV-G/eGFP↑-co-cultures raising EAD incidence from 7.9 to 34.2% (P < 0.001). CONCLUSION Forced fusion of cultured hVSCs with NRVMs yields electrically functional heterokaryons and reduces arrhythmogenicity by preventing EADs, which is, at least partly, attributable to increased repolarization force.
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Affiliation(s)
- Marc C Engels
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands
| | - Saïd F A Askar
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands
| | - Wanchana Jangsangthong
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands
| | - Brian O Bingen
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands
| | - Iolanda Feola
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands
| | - Jia Liu
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands
| | - Rupamanjari Majumder
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands
| | - Michel I M Versteegh
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands Department of Cardiothoracic Surgery, Heart Lung Center Leiden, Leiden University Medical Center, Leiden, The Netherlands
| | - Jerry Braun
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands Department of Cardiothoracic Surgery, Heart Lung Center Leiden, Leiden University Medical Center, Leiden, The Netherlands
| | - Robert J M Klautz
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands Department of Cardiothoracic Surgery, Heart Lung Center Leiden, Leiden University Medical Center, Leiden, The Netherlands
| | - Dirk L Ypey
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands
| | - Antoine A F De Vries
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands
| | - Daniël A Pijnappels
- Laboratory of Experimental Cardiology, Department of Cardiology, Heart Lung Center Leiden, Leiden University Medical Center, Albinusdreef 2, Leiden, RC 2300, The Netherlands
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Schulz R, Görge PM, Görbe A, Ferdinandy P, Lampe PD, Leybaert L. Connexin 43 is an emerging therapeutic target in ischemia/reperfusion injury, cardioprotection and neuroprotection. Pharmacol Ther 2015; 153:90-106. [PMID: 26073311 DOI: 10.1016/j.pharmthera.2015.06.005] [Citation(s) in RCA: 163] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 05/29/2015] [Indexed: 12/22/2022]
Abstract
Connexins are widely distributed proteins in the body that are crucially important for heart and brain functions. Six connexin subunits form a connexon or hemichannel in the plasma membrane. Interactions between two hemichannels in a head-to-head arrangement result in the formation of a gap junction channel. Gap junctions are necessary to coordinate cell function by passing electrical current flow between heart and nerve cells or by allowing exchange of chemical signals and energy substrates. Apart from its localization at the sarcolemma of cardiomyocytes and brain cells, connexins are also found in the mitochondria where they are involved in the regulation of mitochondrial matrix ion fluxes and respiration. Connexin expression is affected by age and gender as well as several pathophysiological alterations such as hypertension, hypertrophy, diabetes, hypercholesterolemia, ischemia, post-myocardial infarction remodeling or heart failure, and post-translationally connexins are modified by phosphorylation/de-phosphorylation and nitros(yl)ation which can modulate channel activity. Using knockout/knockin technology as well as pharmacological approaches, one of the connexins, namely connexin 43, has been identified to be important for cardiac and brain ischemia/reperfusion injuries as well as protection from it. Therefore, the current review will focus on the importance of connexin 43 for irreversible injury of heart and brain tissues following ischemia/reperfusion and will highlight the importance of connexin 43 as an emerging therapeutic target in cardio- and neuroprotection.
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Affiliation(s)
- Rainer Schulz
- Institut für Physiologie, JustusLiebig Universität Giessen, Gießen, Germany.
| | | | - Anikó Görbe
- Cardiovascular Research Group, Department of Biochemistry, Faculty of Medicine, University of Szeged, Hungary; Pharmahungary Group, Szeged, Hungary
| | - Péter Ferdinandy
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary; Pharmahungary Group, Szeged, Hungary
| | - Paul D Lampe
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Luc Leybaert
- Physiology Group, Department Basic Medical Sciences, Ghent University, Belgium
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Exosomes for Intramyocardial Intercellular Communication. Stem Cells Int 2015; 2015:482171. [PMID: 26089917 PMCID: PMC4454760 DOI: 10.1155/2015/482171] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 05/05/2015] [Indexed: 12/31/2022] Open
Abstract
Cross-talk between different cell types plays central roles both in cardiac homeostasis and in adaptive responses of the heart to stress. Cardiomyocytes (CMs) send biological messages to the other cell types present in the heart including endothelial cells (ECs) and fibroblasts. In turn, CMs receive messages from these cells. Recent evidence has now established that exosomes, nanosized secreted extracellular vesicles, are crucial mediators of such messages. CMs, ECs, cardiac fibroblasts, and cardiac progenitor cells (CPCs) release exosomes carrying nonrandom subsets of proteins, lipids, and nucleic acids present in their cells of origin. Exosomes secreted from CMs are internalized by fibroblasts and regulate gene expression in these cells as well as in ECs. CPC-derived exosomes protect CMs against apoptosis while also stimulating angiogenesis. They are rich in cardioprotective and proangiogenic microRNAs such as miR-146, miR-210, and miR-132. When injected into infracted hearts in vivo, CPC-derived exosomes reduce infarct size and improve cardiac function. Thus, exosomes are emerging both as key mediators of intercellular communication in the heart and as therapeutic candidates for heart disease.
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Mondal A, Baker B, Harvey IR, Moreno AP. PerFlexMEA: a thin microporous microelectrode array for in vitro cardiac electrophysiological studies on hetero-cellular bilayers with controlled gap junction communication. LAB ON A CHIP 2015; 15:2037-2048. [PMID: 25797476 DOI: 10.1039/c4lc01212g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The new microelectrode array device presented is called PerFlexMEA and it enables controlled coupling between myocytes and nonmyocytes used in cardiovascular conduction studies. The device consists of an 8 μm thin parylene microporous membrane with a 4 × 5 microelectrode array patterned on one side. Myocytes and nonmyocytes can be plated on either side of the parylene membrane to create a tissue bilayer. The 3-3.5 μm diameter pores allow inter-layer dye and electrical coupling without transmembrane cell migration. Cell migration was found to vary with cell-type and micropore diameter. Pore density can be varied based on desired coupling ratio. The flexible parylene membrane is packaged between two rigid thermoplastic layers, such that the microelectrode array region is exposed, while the rest of the device remains insulated. The packaged PerFlexMEA fits in a 60 mm culture dish. Recording experiments are performed by simply plugging it into a commercially available multielectrode amplifier system. Recorded signals were processed and analysed using scripts generated in MATLAB. Our experimental results provide evidence of the reliability of this device, as conduction velocity was observed to decrease after inducing lateral hetero-cellular controlled coupling between myocytes and HeLa cells expressing connexin 43.
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Affiliation(s)
- A Mondal
- Nora Eccles Harrison Cardiovascular Research & Training Institute, University of Utah, 95 South 2000 East, Salt Lake City, UT 84112-5000, USA.
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McDowell KS, Zahid S, Vadakkumpadan F, Blauer J, MacLeod RS, Trayanova NA. Virtual electrophysiological study of atrial fibrillation in fibrotic remodeling. PLoS One 2015; 10:e0117110. [PMID: 25692857 PMCID: PMC4333565 DOI: 10.1371/journal.pone.0117110] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 12/18/2014] [Indexed: 12/19/2022] Open
Abstract
Research has indicated that atrial fibrillation (AF) ablation failure is related to the presence of atrial fibrosis. However it remains unclear whether this information can be successfully used in predicting the optimal ablation targets for AF termination. We aimed to provide a proof-of-concept that patient-specific virtual electrophysiological study that combines i) atrial structure and fibrosis distribution from clinical MRI and ii) modeling of atrial electrophysiology, could be used to predict: (1) how fibrosis distribution determines the locations from which paced beats degrade into AF; (2) the dynamic behavior of persistent AF rotors; and (3) the optimal ablation targets in each patient. Four MRI-based patient-specific models of fibrotic left atria were generated, ranging in fibrosis amount. Virtual electrophysiological studies were performed in these models, and where AF was inducible, the dynamics of AF were used to determine the ablation locations that render AF non-inducible. In 2 of the 4 models patient-specific models AF was induced; in these models the distance between a given pacing location and the closest fibrotic region determined whether AF was inducible from that particular location, with only the mid-range distances resulting in arrhythmia. Phase singularities of persistent rotors were found to move within restricted regions of tissue, which were independent of the pacing location from which AF was induced. Electrophysiological sensitivity analysis demonstrated that these regions changed little with variations in electrophysiological parameters. Patient-specific distribution of fibrosis was thus found to be a critical component of AF initiation and maintenance. When the restricted regions encompassing the meander of the persistent phase singularities were modeled as ablation lesions, AF could no longer be induced. The study demonstrates that a patient-specific modeling approach to identify non-invasively AF ablation targets prior to the clinical procedure is feasible.
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Affiliation(s)
- Kathleen S. McDowell
- The Johns Hopkins University, Department of Biomedical Engineering, Baltimore, Maryland, United States of America
| | - Sohail Zahid
- The Johns Hopkins University, Department of Biomedical Engineering, Baltimore, Maryland, United States of America
| | - Fijoy Vadakkumpadan
- The Johns Hopkins University, Department of Biomedical Engineering, Baltimore, Maryland, United States of America
| | - Joshua Blauer
- University of Utah, Comprehensive Arrhythmia Research and Management Center, School of Medicine, Salt Lake City, Utah, United States of America
| | - Rob S. MacLeod
- University of Utah, Comprehensive Arrhythmia Research and Management Center, School of Medicine, Salt Lake City, Utah, United States of America
| | - Natalia A. Trayanova
- The Johns Hopkins University, Department of Biomedical Engineering, Baltimore, Maryland, United States of America
- * E-mail:
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The role of extracellular matrix in age-related conduction disorders: a forgotten player? JOURNAL OF GERIATRIC CARDIOLOGY : JGC 2015; 12:76-82. [PMID: 25678907 PMCID: PMC4308461 DOI: 10.11909/j.issn.1671-5411.2015.01.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 11/21/2014] [Accepted: 11/28/2014] [Indexed: 12/21/2022]
Abstract
Cardiovascular aging is a physiological process gradually leading to structural degeneration and functional loss of all the cardiac and vascular components. Conduction system is also deeply influenced by the aging process with relevant reflexes in the clinical side. Age-related arrhythmias carry significant morbidity and mortality and represent a clinical and economical burden. An important and unjustly unrecognized actor in the pathophysiology of aging is represented by the extracellular matrix (ECM) that not only structurally supports the heart determining its mechanical and functional properties, but also sends a biological signaling regulating cellular function and maintaining tissue homeostasis. At the biophysical level, cardiac ECM exhibits a peculiar degree of anisotropy, which is among the main determinants of the conductive properties of the specialized electrical conduction system. Age-associated alterations of cardiac ECM are therefore able to profoundly affect the function of the conduction system with striking impact on the patient clinical conditions. This review will focus on the ECM changes that occur during aging in the heart conduction system and on their translation to the clinical scenario. Potential diagnostic and therapeutical perspectives arising from the knowledge on ECM age-associated alterations are further discussed.
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Krul SPJ, Berger WR, Smit NW, van Amersfoorth SCM, Driessen AHG, van Boven WJ, Fiolet JWT, van Ginneken ACG, van der Wal AC, de Bakker JMT, Coronel R, de Groot JR. Atrial fibrosis and conduction slowing in the left atrial appendage of patients undergoing thoracoscopic surgical pulmonary vein isolation for atrial fibrillation. Circ Arrhythm Electrophysiol 2015; 8:288-95. [PMID: 25673630 DOI: 10.1161/circep.114.001752] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 01/27/2015] [Indexed: 12/20/2022]
Abstract
BACKGROUND Atrial fibrosis is an important component of the arrhythmogenic substrate in patients with atrial fibrillation (AF). We studied the effect of interstitial fibrosis on conduction velocity (CV) in the left atrial appendage of patients with AF. METHODS AND RESULTS Thirty-five left atrial appendages were obtained during AF surgery. Preparations were superfused and stimulated at 100 beats per minute. Activation was recorded with optical mapping. Longitudinal CV (CVL), transverse CV (CVT), and activation times (> 2 mm distance) were measured. Interstitial collagen was quantified and graded qualitatively. The presence of fibroblasts and myofibroblasts was assessed immunohistochemically. Mean CVL was 0.55 ± 0.22 m/s, mean CVT was 0.25 ± 0.15 m/s, and the mean activation time was 9.31 ± 5.45 ms. The amount of fibrosis was unrelated to CV or patient characteristics. CVL was higher in left atrial appendages with thick compared with thin interstitial collagen strands (0.77 ± 0.22 versus 0.48 ± 0.19 m/s; P = 0.012), which were more frequently present in persistent patients with AF. CVT was not significantly different (P = 0.47), but activation time was 14.93 ± 4.12 versus 7.95 ± 4.12 ms in patients with thick versus thin interstitial collagen strands, respectively (P = 0.004). Fibroblasts were abundantly present and were associated with the presence of thick interstitial collagen strands (P = 0.008). Myofibroblasts were not detected in the left atrial appendage. CONCLUSIONS In patients with AF, thick interstitial collagen strands are associated with higher CVL and increased activation time. Our observations demonstrate that the severity and structure of local interstitial fibrosis is associated with atrial conduction abnormalities, presenting an arrhythmogenic substrate for atrial re-entry.
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Affiliation(s)
- Sébastien P J Krul
- From the Heart Center, Departments of Clinical and Experimental Cardiology (S.P.J.K., W.R.B., N.W.S., S.C.M.v.A., J.W.T.F., J.M.T.d.B., R.C., J.R.d.G.) and Cardiothoracic Surgery (A.H.G.D., W.J.v.B.), Departments of Anatomy, Embryology, and Physiology (A.C.G.v.G.) and Pathology (A.C.v.d.W.), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands (J.M.T.d.B.); and L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université de Bordeaux, Bordeaux, France (R.C.)
| | - Wouter R Berger
- From the Heart Center, Departments of Clinical and Experimental Cardiology (S.P.J.K., W.R.B., N.W.S., S.C.M.v.A., J.W.T.F., J.M.T.d.B., R.C., J.R.d.G.) and Cardiothoracic Surgery (A.H.G.D., W.J.v.B.), Departments of Anatomy, Embryology, and Physiology (A.C.G.v.G.) and Pathology (A.C.v.d.W.), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands (J.M.T.d.B.); and L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université de Bordeaux, Bordeaux, France (R.C.)
| | - Nicoline W Smit
- From the Heart Center, Departments of Clinical and Experimental Cardiology (S.P.J.K., W.R.B., N.W.S., S.C.M.v.A., J.W.T.F., J.M.T.d.B., R.C., J.R.d.G.) and Cardiothoracic Surgery (A.H.G.D., W.J.v.B.), Departments of Anatomy, Embryology, and Physiology (A.C.G.v.G.) and Pathology (A.C.v.d.W.), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands (J.M.T.d.B.); and L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université de Bordeaux, Bordeaux, France (R.C.)
| | - Shirley C M van Amersfoorth
- From the Heart Center, Departments of Clinical and Experimental Cardiology (S.P.J.K., W.R.B., N.W.S., S.C.M.v.A., J.W.T.F., J.M.T.d.B., R.C., J.R.d.G.) and Cardiothoracic Surgery (A.H.G.D., W.J.v.B.), Departments of Anatomy, Embryology, and Physiology (A.C.G.v.G.) and Pathology (A.C.v.d.W.), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands (J.M.T.d.B.); and L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université de Bordeaux, Bordeaux, France (R.C.)
| | - Antoine H G Driessen
- From the Heart Center, Departments of Clinical and Experimental Cardiology (S.P.J.K., W.R.B., N.W.S., S.C.M.v.A., J.W.T.F., J.M.T.d.B., R.C., J.R.d.G.) and Cardiothoracic Surgery (A.H.G.D., W.J.v.B.), Departments of Anatomy, Embryology, and Physiology (A.C.G.v.G.) and Pathology (A.C.v.d.W.), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands (J.M.T.d.B.); and L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université de Bordeaux, Bordeaux, France (R.C.)
| | - Wim Jan van Boven
- From the Heart Center, Departments of Clinical and Experimental Cardiology (S.P.J.K., W.R.B., N.W.S., S.C.M.v.A., J.W.T.F., J.M.T.d.B., R.C., J.R.d.G.) and Cardiothoracic Surgery (A.H.G.D., W.J.v.B.), Departments of Anatomy, Embryology, and Physiology (A.C.G.v.G.) and Pathology (A.C.v.d.W.), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands (J.M.T.d.B.); and L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université de Bordeaux, Bordeaux, France (R.C.)
| | - Jan W T Fiolet
- From the Heart Center, Departments of Clinical and Experimental Cardiology (S.P.J.K., W.R.B., N.W.S., S.C.M.v.A., J.W.T.F., J.M.T.d.B., R.C., J.R.d.G.) and Cardiothoracic Surgery (A.H.G.D., W.J.v.B.), Departments of Anatomy, Embryology, and Physiology (A.C.G.v.G.) and Pathology (A.C.v.d.W.), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands (J.M.T.d.B.); and L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université de Bordeaux, Bordeaux, France (R.C.)
| | - Antoni C G van Ginneken
- From the Heart Center, Departments of Clinical and Experimental Cardiology (S.P.J.K., W.R.B., N.W.S., S.C.M.v.A., J.W.T.F., J.M.T.d.B., R.C., J.R.d.G.) and Cardiothoracic Surgery (A.H.G.D., W.J.v.B.), Departments of Anatomy, Embryology, and Physiology (A.C.G.v.G.) and Pathology (A.C.v.d.W.), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands (J.M.T.d.B.); and L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université de Bordeaux, Bordeaux, France (R.C.)
| | - Allard C van der Wal
- From the Heart Center, Departments of Clinical and Experimental Cardiology (S.P.J.K., W.R.B., N.W.S., S.C.M.v.A., J.W.T.F., J.M.T.d.B., R.C., J.R.d.G.) and Cardiothoracic Surgery (A.H.G.D., W.J.v.B.), Departments of Anatomy, Embryology, and Physiology (A.C.G.v.G.) and Pathology (A.C.v.d.W.), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands (J.M.T.d.B.); and L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université de Bordeaux, Bordeaux, France (R.C.)
| | - Jacques M T de Bakker
- From the Heart Center, Departments of Clinical and Experimental Cardiology (S.P.J.K., W.R.B., N.W.S., S.C.M.v.A., J.W.T.F., J.M.T.d.B., R.C., J.R.d.G.) and Cardiothoracic Surgery (A.H.G.D., W.J.v.B.), Departments of Anatomy, Embryology, and Physiology (A.C.G.v.G.) and Pathology (A.C.v.d.W.), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands (J.M.T.d.B.); and L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université de Bordeaux, Bordeaux, France (R.C.)
| | - Ruben Coronel
- From the Heart Center, Departments of Clinical and Experimental Cardiology (S.P.J.K., W.R.B., N.W.S., S.C.M.v.A., J.W.T.F., J.M.T.d.B., R.C., J.R.d.G.) and Cardiothoracic Surgery (A.H.G.D., W.J.v.B.), Departments of Anatomy, Embryology, and Physiology (A.C.G.v.G.) and Pathology (A.C.v.d.W.), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands (J.M.T.d.B.); and L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université de Bordeaux, Bordeaux, France (R.C.)
| | - Joris R de Groot
- From the Heart Center, Departments of Clinical and Experimental Cardiology (S.P.J.K., W.R.B., N.W.S., S.C.M.v.A., J.W.T.F., J.M.T.d.B., R.C., J.R.d.G.) and Cardiothoracic Surgery (A.H.G.D., W.J.v.B.), Departments of Anatomy, Embryology, and Physiology (A.C.G.v.G.) and Pathology (A.C.v.d.W.), Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands (J.M.T.d.B.); and L'Institut de RYthmologie et Modélisation Cardiaque (LIRYC), Université de Bordeaux, Bordeaux, France (R.C.).
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73
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Cartledge JE, Kane C, Dias P, Tesfom M, Clarke L, Mckee B, Al Ayoubi S, Chester A, Yacoub MH, Camelliti P, Terracciano CM. Functional crosstalk between cardiac fibroblasts and adult cardiomyocytes by soluble mediators. Cardiovasc Res 2015; 105:260-70. [DOI: 10.1093/cvr/cvu264] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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74
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Detailed characterization of microRNA changes in a canine heart failure model: Relationship to arrhythmogenic structural remodeling. J Mol Cell Cardiol 2014; 77:113-24. [DOI: 10.1016/j.yjmcc.2014.10.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 09/04/2014] [Accepted: 10/01/2014] [Indexed: 11/22/2022]
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75
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Gao Y, Connell JP, Wadhwa L, Ruano R, Jacot JG. Amniotic fluid-derived stem cells demonstrated cardiogenic potential in indirect co-culture with human cardiac cells. Ann Biomed Eng 2014; 42:2490-500. [PMID: 25266932 PMCID: PMC4241123 DOI: 10.1007/s10439-014-1114-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 09/05/2014] [Indexed: 01/15/2023]
Abstract
Amniotic fluid-derived stem cells (AFSC) have been shown to be broadly multipotent and non-tumorogenic. Previous studies of direct mixing of AFSC and neonatal rat ventricle myocytes indicated evidence of AFSC cardiogenesis. In this study, we examined human AFSC cardiogenic potential in indirect co-culture with human cardiac cells in conditions that eliminated the possibility of cell fusion. Human AFSC in contact with human cardiac cells showed expression of cardiac troponin T (cTnT) in immunohistochemistry, and no evidence of cell fusion was found through fluorescent in situ hybridization. When indirectly co-cultured with cardiac cells, human AFSC in contact with cardiac cells across a thin porous membrane showed a statistically significant increase in cTnT expression compared to non-contact conditions but lacked upregulation of calcium modulating proteins and did not have functional or morphological characteristics of mature cardiomyocytes. This suggests that contact is a necessary but not sufficient condition for AFSC cardiac differentiation in co-culture with cardiac cells.
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Affiliation(s)
- Yang Gao
- Department of Bioengineering, Rice University, Houston, Texas
| | | | - Lalita Wadhwa
- Division of Congenital Heart Surgery, Texas Children’s Hospital, Houston, Texas
| | - Rodrigo Ruano
- Fetal Center, Pavilion for Women, Texas Children’s Hospital, Houston, Texas
- Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas
| | - Jeffrey G. Jacot
- Department of Bioengineering, Rice University, Houston, Texas
- Division of Congenital Heart Surgery, Texas Children’s Hospital, Houston, Texas
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76
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Trayanova NA, Boyle PM, Arevalo HJ, Zahid S. Exploring susceptibility to atrial and ventricular arrhythmias resulting from remodeling of the passive electrical properties in the heart: a simulation approach. Front Physiol 2014; 5:435. [PMID: 25429272 PMCID: PMC4228852 DOI: 10.3389/fphys.2014.00435] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 10/24/2014] [Indexed: 12/19/2022] Open
Abstract
Under diseased conditions, remodeling of the cardiac tissue properties (“passive properties”) takes place; these are aspects of electrophysiological behavior that are not associated with active ion transport across cell membranes. Remodeling of the passive electrophysiological properties most often results from structural remodeling, such as gap junction down-regulation and lateralization, fibrotic growth infiltrating the myocardium, or the development of an infarct scar. Such structural remodeling renders atrial or ventricular tissue as a major substrate for arrhythmias. The current review focuses on these aspects of cardiac arrhythmogenesis. Due to the inherent complexity of cardiac arrhythmias, computer simulations have provided means to elucidate interactions pertinent to this spatial scale. Here we review the current state-of-the-art in modeling atrial and ventricular arrhythmogenesis as arising from the disease-induced changes in the passive tissue properties, as well as the contributions these modeling studies have made to our understanding of the mechanisms of arrhythmias in the heart. Because of the rapid advance of structural imaging methodologies in cardiac electrophysiology, we chose to present studies that have used such imaging methodologies to construct geometrically realistic models of cardiac tissue, or the organ itself, where the regional remodeling properties of the myocardium can be represented in a realistic way. We emphasize how the acquired knowledge can be used to pave the way for clinical applications of cardiac organ modeling under the conditions of structural remodeling.
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Affiliation(s)
- Natalia A Trayanova
- Department of Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University Baltimore, MD, USA
| | - Patrick M Boyle
- Department of Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University Baltimore, MD, USA
| | - Hermenegild J Arevalo
- Department of Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University Baltimore, MD, USA
| | - Sohail Zahid
- Department of Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University Baltimore, MD, USA
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77
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Smit NW, Coronel R. Stem cells can form gap junctions with cardiac myocytes and exert pro-arrhythmic effects. Front Physiol 2014; 5:419. [PMID: 25400586 PMCID: PMC4212603 DOI: 10.3389/fphys.2014.00419] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 10/10/2014] [Indexed: 12/24/2022] Open
Abstract
Stem cell therapy has been suggested to be a promising option for regeneration of injured myocardium, for example following a myocardial infarction. For clinical use cell-based therapies have to be safe and applicable and are aimed to renovate the architecture of the heart. Yet for functional and coordinated activity synchronized with the host myocardium stem cells have to be capable of forming electrical connections with resident cardiomyocytes. In this paper we discuss whether stem cells are capable of establishing functional electrotonic connections with cardiomyocytes and whether these may generate a risk for arrhythmias. Application of stem cells in the clinical setting with outcomes concerning arrhythmogenic safety and future perspectives will also briefly be touched upon.
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Affiliation(s)
- Nicoline W Smit
- Department of Clinical and Experimental Cardiology, Heart Centre, Academic Medical Centre, University of Amsterdam Amsterdam, Netherlands
| | - Ruben Coronel
- Department of Clinical and Experimental Cardiology, Heart Centre, Academic Medical Centre, University of Amsterdam Amsterdam, Netherlands ; L'Institut de RYthmologie et modélisation Cardiaque, Université Bordeaux Segalen Bordeaux, France
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78
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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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79
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Trayanova NA. Mathematical approaches to understanding and imaging atrial fibrillation: significance for mechanisms and management. Circ Res 2014; 114:1516-31. [PMID: 24763468 DOI: 10.1161/circresaha.114.302240] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Atrial fibrillation (AF) is the most common sustained arrhythmia in humans. The mechanisms that govern AF initiation and persistence are highly complex, of dynamic nature, and involve interactions across multiple temporal and spatial scales in the atria. This article aims to review the mathematical modeling and computer simulation approaches to understanding AF mechanisms and aiding in its management. Various atrial modeling approaches are presented, with descriptions of the methodological basis and advancements in both lower-dimensional and realistic geometry models. A review of the most significant mechanistic insights made by atrial simulations is provided. The article showcases the contributions that atrial modeling and simulation have made not only to our understanding of the pathophysiology of atrial arrhythmias, but also to the development of AF management approaches. A summary of the future developments envisioned for the field of atrial simulation and modeling is also presented. The review contends that computational models of the atria assembled with data from clinical imaging modalities that incorporate electrophysiological and structural remodeling could become a first line of screening for new AF therapies and approaches, new diagnostic developments, and new methods for arrhythmia prevention.
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Affiliation(s)
- Natalia A Trayanova
- From the Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD
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80
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Andrade J, Khairy P, Dobrev D, Nattel S. The clinical profile and pathophysiology of atrial fibrillation: relationships among clinical features, epidemiology, and mechanisms. Circ Res 2014; 114:1453-68. [PMID: 24763464 DOI: 10.1161/circresaha.114.303211] [Citation(s) in RCA: 818] [Impact Index Per Article: 81.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Atrial fibrillation (AF) is the most common arrhythmia (estimated lifetime risk, 22%-26%). The aim of this article is to review the clinical epidemiological features of AF and to relate them to underlying mechanisms. Long-established risk factors for AF include aging, male sex, hypertension, valve disease, left ventricular dysfunction, obesity, and alcohol consumption. Emerging risk factors include prehypertension, increased pulse pressure, obstructive sleep apnea, high-level physical training, diastolic dysfunction, predisposing gene variants, hypertrophic cardiomyopathy, and congenital heart disease. Potential risk factors are coronary artery disease, kidney disease, systemic inflammation, pericardial fat, and tobacco use. AF has substantial population health consequences, including impaired quality of life, increased hospitalization rates, stroke occurrence, and increased medical costs. The pathophysiology of AF centers around 4 general types of disturbances that promote ectopic firing and reentrant mechanisms, and include the following: (1) ion channel dysfunction, (2) Ca(2+)-handling abnormalities, (3) structural remodeling, and (4) autonomic neural dysregulation. Aging, hypertension, valve disease, heart failure, myocardial infarction, obesity, smoking, diabetes mellitus, thyroid dysfunction, and endurance exercise training all cause structural remodeling. Heart failure and prior atrial infarction also cause Ca(2+)-handling abnormalities that lead to focal ectopic firing via delayed afterdepolarizations/triggered activity. Neural dysregulation is central to atrial arrhythmogenesis associated with endurance exercise training and occlusive coronary artery disease. Monogenic causes of AF typically promote the arrhythmia via ion channel dysfunction, but the mechanisms of the more common polygenic risk factors are still poorly understood and under intense investigation. Better recognition of the clinical epidemiology of AF, as well as an improved appreciation of the underlying mechanisms, is needed to develop improved methods for AF prevention and management.
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Affiliation(s)
- Jason Andrade
- From Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada (J.A., P.K., S.N.); Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada (J.A.); and Faculty of Medicine, Institute of Pharmacology, University Duisburg-Essen, Essen, Germany (D.D.)
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81
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Wu CT, Qi XY, Huang H, Naud P, Dawson K, Yeh YH, Harada M, Kuo CT, Nattel S. Disease and region-related cardiac fibroblast potassium current variations and potential functional significance. Cardiovasc Res 2014; 102:487-96. [PMID: 24596399 DOI: 10.1093/cvr/cvu055] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
AIMS Fibroblasts, which play an important role in cardiac function/dysfunction, including arrhythmogenesis, have voltage-dependent (Kv) currents of unknown importance. Here, we assessed the differential expression of Kv currents between atrial and ventricular fibroblasts from control dogs and dogs with an atrial arrhythmogenic substrate caused by congestive heart failure (CHF). METHODS AND RESULTS Left atrial (LA) and ventricular (LV) fibroblasts were freshly isolated from control and CHF dogs (2-week ventricular tachypacing, 240 bpm). Kv currents were measured with whole-cell voltage-clamp, mRNA by quantitative polymerase chain reaction (qPCR) and fibroblast proliferation by (3)H-thymidine incorporation. Robust voltage-dependent tetraethylammonium (TEA)-sensitive K(+) currents (IC50 ∼1 mM) were recorded. The morphologies and TEA responses of LA and LV fibroblast Kv currents were similar. LV fibroblast Kv-current densities were significantly greater than LA, and Kv-current densities were significantly less in CHF than control. The mRNA expression of Kv-channel subunits Kv1.5 and Kv4.3 was less in LA vs. LV fibroblasts and was down-regulated in CHF, consistent with K(+)-current recordings. Ca(2+)-dependent K(+)-channel subunit (KCa1.1) mRNA and currents were less expressed in LV vs. LA fibroblasts. Inhibiting LA fibroblast K(+) current with 1 mmol/L of TEA or KCa1.1 current with paxilline increased proliferation. CONCLUSIONS Fibroblast Kv-current expression is smaller in CHF vs. control, as well as LA vs. LV. KCa1.1 current is greater in LA vs. LV. Suppressing Kv current with TEA enhances fibroblast proliferation, suggesting that Kv current might act to check fibroblast proliferation and that reduced Kv current in CHF may contribute to fibrosis. Fibroblast Kv-current remodelling may play a role in the atrial fibrillation (AF) substrate; modulating fibroblast K(+) channels may present a novel strategy to prevent fibrosis and AF.
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Affiliation(s)
- Chia-Tung Wu
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8 Chang-Gung Memorial Hospital and University, Taoyuan, Taiwan, Republic of China
| | - Xiao-Yan Qi
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8
| | - Hai Huang
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8
| | - Patrice Naud
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8
| | - Kristin Dawson
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8 Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - Yung-Hsin Yeh
- Chang-Gung Memorial Hospital and University, Taoyuan, Taiwan, Republic of China
| | - Masahide Harada
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8 Department of Cardiology, Hamamatsu Medical Center, Hamamatsu, Japan
| | - Chi-Tai Kuo
- Chang-Gung Memorial Hospital and University, Taoyuan, Taiwan, Republic of China
| | - Stanley Nattel
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8 Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
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82
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van Spreeuwel ACC, Bax NAM, Bastiaens AJ, Foolen J, Loerakker S, Borochin M, van der Schaft DWJ, Chen CS, Baaijens FPT, Bouten CVC. The influence of matrix (an)isotropy on cardiomyocyte contraction in engineered cardiac microtissues. Integr Biol (Camb) 2014; 6:422-9. [PMID: 24549279 DOI: 10.1039/c3ib40219c] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the cardiac microenvironment, cardiomyocytes (CMs) are embedded in an aligned and structured extracellular matrix (ECM) to maintain the coordinated contractile function of the heart. The cardiac fibroblast (cFB) is the main cell type responsible for producing and remodeling this matrix. In cardiac diseases, however, adverse remodeling and CM death may lead to deterioration of the aligned myocardial structure. Here, we present an in vitro cardiac model system with uniaxial and biaxial constraints to induce (an)isotropy in 3D microtissues, thereby mimicking 'healthy' aligned and 'diseased' disorganized cardiac matrices. A mixture of neonatal mouse CMs and cFBs was resuspended in a collagen-matrigel hydrogel and seeded to form microtissues to recapitulate the in vivo cellular composition. Matrix disarray led to a stellate cell shape and a disorganized sarcomere organization, while CMs in aligned matrices were more elongated and had aligned sarcomeres. Although matrix disarray has no detrimental effect on the force generated by the CMs, it did have a negative effect on the homogeneity of contraction force distribution. Furthermore, proliferation of the cFBs affected microtissue contraction as indicated by the negative correlation between the percentage of cFBs in the microtissues and their beating frequency. These results suggest that in regeneration of the diseased heart, reorganization of the disorganized matrix will contribute to recover the coordinated contraction but restoring the ratio in cellular composition (CMs and cFBs) is also a prerequisite to completely regain tissue function.
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Affiliation(s)
- A C C van Spreeuwel
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
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83
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Bian W, Badie N, Himel HD, Bursac N. Robust T-tubulation and maturation of cardiomyocytes using tissue-engineered epicardial mimetics. Biomaterials 2014; 35:3819-28. [PMID: 24508078 DOI: 10.1016/j.biomaterials.2014.01.045] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Accepted: 01/20/2014] [Indexed: 01/27/2023]
Abstract
Complex three-dimensional (3-D) heart structure is an important determinant of cardiac electrical and mechanical function. In this study, we set to develop a versatile tissue-engineered system that can promote important aspects of cardiac functional maturation and reproduce variations in myofiber directions present in native ventricular epicardium. We cultured neonatal rat cardiomyocytes within a 3-D hydrogel environment using microfabricated elastomeric molds with hexagonal posts. By varying individual post orientations along the directions derived from diffusion tensor magnetic resonance imaging (DTMRI) maps of human ventricle, we created large (2.5 × 2.5 cm(2)) 3-D cardiac tissue patches with cardiomyocyte alignment that replicated human epicardial fiber orientations. After 3 weeks of culture, the advanced structural and functional maturation of the engineered 3-D cardiac tissues compared to age-matched 2-D monolayers was evident from: 1) the presence of dense, aligned and electromechanically-coupled cardiomyocytes, quiescent fibroblasts, and interspersed capillary-like structures, 2) action potential propagation with near-adult conduction velocity and directional dependence on local cardiomyocyte orientation, and 3) robust formation of T-tubules aligned with Z-disks, co-localization of L-type Ca(2+) channels and ryanodine receptors, and accelerated Ca(2+) transient kinetics. This biomimetic tissue-engineered platform can enable systematic in vitro studies of cardiac structure-function relationships and promote the development of advanced tissue engineering strategies for cardiac repair and regeneration.
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Affiliation(s)
- Weining Bian
- Department of Biomedical Engineering, Duke University, 3000 Science Dr, Hudson Hall 136, Durham, NC 27708, USA
| | - Nima Badie
- Department of Biomedical Engineering, Duke University, 3000 Science Dr, Hudson Hall 136, Durham, NC 27708, USA
| | - Herman D Himel
- Department of Biomedical Engineering, Duke University, 3000 Science Dr, Hudson Hall 136, Durham, NC 27708, USA
| | - Nenad Bursac
- Department of Biomedical Engineering, Duke University, 3000 Science Dr, Hudson Hall 136, Durham, NC 27708, USA.
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84
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Sluijter JP, Verhage V, Deddens JC, van den Akker F, Doevendans PA. Microvesicles and exosomes for intracardiac communication. Cardiovasc Res 2014; 102:302-11. [DOI: 10.1093/cvr/cvu022] [Citation(s) in RCA: 181] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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85
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McDowell KS, Vadakkumpadan F, Blake R, Blauer J, Plank G, Macleod RS, Trayanova NA. Mechanistic inquiry into the role of tissue remodeling in fibrotic lesions in human atrial fibrillation. Biophys J 2014; 104:2764-73. [PMID: 23790385 DOI: 10.1016/j.bpj.2013.05.025] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 04/23/2013] [Accepted: 05/10/2013] [Indexed: 01/23/2023] Open
Abstract
Atrial fibrillation (AF), the most common arrhythmia in humans, is initiated when triggered activity from the pulmonary veins propagates into atrial tissue and degrades into reentrant activity. Although experimental and clinical findings show a correlation between atrial fibrosis and AF, the causal relationship between the two remains elusive. This study used an array of 3D computational models with different representations of fibrosis based on a patient-specific atrial geometry with accurate fibrotic distribution to determine the mechanisms by which fibrosis underlies the degradation of a pulmonary vein ectopic beat into AF. Fibrotic lesions in models were represented with combinations of: gap junction remodeling; collagen deposition; and myofibroblast proliferation with electrotonic or paracrine effects on neighboring myocytes. The study found that the occurrence of gap junction remodeling and the subsequent conduction slowing in the fibrotic lesions was a necessary but not sufficient condition for AF development, whereas myofibroblast proliferation and the subsequent electrophysiological effect on neighboring myocytes within the fibrotic lesions was the sufficient condition necessary for reentry formation. Collagen did not alter the arrhythmogenic outcome resulting from the other fibrosis components. Reentrant circuits formed throughout the noncontiguous fibrotic lesions, without anchoring to a specific fibrotic lesion.
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Affiliation(s)
- Kathleen S McDowell
- The Johns Hopkins University, Department of Biomedical Engineering and Institute for Computational Medicine, Baltimore, Maryland, USA
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86
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Abstract
Extracellular vesicles (EV), including exosomes, microvesicles and apoptotic bodies, are released from numerous cell types and are involved in intercellular communication, physiological functions and the pathology of disease. They have been shown to carry and transfer a wide range of cargo including proteins, lipids and nucleic acids. The role of EVs in cardiac physiology and heart disease is an emerging field that has produced intriguing findings in recent years. This review will outline what is currently known about EVs in the cardiovascular system, including cellular origins, functional roles and utility as biomarkers and potential therapeutics.
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Affiliation(s)
- Kirsty M Danielson
- Cardiovascular Institute, Beth Israel Deaconess Medical Center, Boston, MA
| | - Saumya Das
- Cardiovascular Institute, Beth Israel Deaconess Medical Center, Boston, MA
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87
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Nguyen H, Badie N, McSpadden L, Pedrotty D, Bursac N. Quantifying electrical interactions between cardiomyocytes and other cells in micropatterned cell pairs. Methods Mol Biol 2014; 1181:249-62. [PMID: 25070342 PMCID: PMC4219610 DOI: 10.1007/978-1-4939-1047-2_21] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Micropatterning is a powerful technique to control cell shape and position on a culture substrate. In this chapter, we describe the method to reproducibly create large numbers of micropatterned heterotypic cell pairs with defined size, shape, and length of cell-cell contact. These cell pairs can be utilized in patch clamp recordings to quantify electrical interactions between cardiomyocytes and non-cardiomyocytes.
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Affiliation(s)
- Hung Nguyen
- Department of Biomedical Engineering, Duke University, 3000 Science Drive, Hudson Hall 136, 90281, Durham, NC, USA
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88
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Nguyen TP, Qu Z, Weiss JN. Cardiac fibrosis and arrhythmogenesis: the road to repair is paved with perils. J Mol Cell Cardiol 2013; 70:83-91. [PMID: 24184999 DOI: 10.1016/j.yjmcc.2013.10.018] [Citation(s) in RCA: 211] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 10/12/2013] [Accepted: 10/22/2013] [Indexed: 01/02/2023]
Abstract
In the healthy heart, cardiac myocytes form an electrical syncytium embedded in a supportive fibroblast-rich extracellular matrix designed to optimize the electromechanical coupling for maximal contractile efficiency of the heart. In the injured heart, however, fibroblasts are activated and differentiate into myofibroblasts that proliferate and generate fibrosis as a component of the wound-healing response. This review discusses how fibroblasts and fibrosis, while essential for maintaining the structural integrity of the heart wall after injury, have undesirable electrophysiological effects by disrupting the normal electrical connectivity of cardiac tissue to increase the vulnerability to arrhythmias. We emphasize the dual contribution of fibrosis in altering source-sink relationships to create a vulnerable substrate while simultaneously facilitating the emergence of triggers such as afterdepolarization-induced premature ventricular complexes-both factors combining synergistically to promote initiation of reentry. We also discuss the potential role of fibroblasts and myofibroblasts in directly altering myocyte electrophysiology in a pro-arrhythmic fashion. Insight into these processes may open up novel therapeutic strategies for preventing and treating arrhythmias in the setting of heart disease as well as avoiding potential arrhythmogenic consequences of cell-based cardiac regeneration therapy. This article is part of a Special Issue entitled "Myocyte-Fibroblast Signaling in Myocardium."
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Affiliation(s)
- Thao P Nguyen
- UCLA Cardiovascular Research Laboratory and the Departments of Medicine (Division of Cardiology) and Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
| | - Zhilin Qu
- UCLA Cardiovascular Research Laboratory and the Departments of Medicine (Division of Cardiology) and Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - James N Weiss
- UCLA Cardiovascular Research Laboratory and the Departments of Medicine (Division of Cardiology) and Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
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89
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Fujiu K, Nagai R. Contributions of cardiomyocyte–cardiac fibroblast–immune cell interactions in heart failure development. Basic Res Cardiol 2013; 108:357. [DOI: 10.1007/s00395-013-0357-x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 03/13/2013] [Accepted: 03/21/2013] [Indexed: 12/20/2022]
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90
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Zhang D, Shadrin IY, Lam J, Xian HQ, Snodgrass HR, Bursac N. Tissue-engineered cardiac patch for advanced functional maturation of human ESC-derived cardiomyocytes. Biomaterials 2013; 34:5813-20. [PMID: 23642535 DOI: 10.1016/j.biomaterials.2013.04.026] [Citation(s) in RCA: 399] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 04/11/2013] [Indexed: 12/12/2022]
Abstract
Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) provide a promising source for cell therapy and drug screening. Several high-yield protocols exist for hESC-CM production; however, methods to significantly advance hESC-CM maturation are still lacking. Building on our previous experience with mouse ESC-CMs, we investigated the effects of 3-dimensional (3D) tissue-engineered culture environment and cardiomyocyte purity on structural and functional maturation of hESC-CMs. 2D monolayer and 3D fibrin-based cardiac patch cultures were generated using dissociated cells from differentiated Hes2 embryoid bodies containing varying percentage (48-90%) of CD172a (SIRPA)-positive cardiomyocytes. hESC-CMs within the patch were aligned uniformly by locally controlling the direction of passive tension. Compared to hESC-CMs in age (2 weeks) and purity (48-65%) matched 2D monolayers, hESC-CMs in 3D patches exhibited significantly higher conduction velocities (CVs), longer sarcomeres (2.09 ± 0.02 vs. 1.77 ± 0.01 μm), and enhanced expression of genes involved in cardiac contractile function, including cTnT, αMHC, CASQ2 and SERCA2. The CVs in cardiac patches increased with cardiomyocyte purity, reaching 25.1 cm/s in patches constructed with 90% hESC-CMs. Maximum contractile force amplitudes and active stresses of cardiac patches averaged to 3.0 ± 1.1 mN and 11.8 ± 4.5 mN/mm(2), respectively. Moreover, contractile force per input cardiomyocyte averaged to 5.7 ± 1.1 nN/cell and showed a negative correlation with hESC-CM purity. Finally, patches exhibited significant positive inotropy with isoproterenol administration (1.7 ± 0.3-fold force increase, EC50 = 95.1 nm). These results demonstrate highly advanced levels of hESC-CM maturation after 2 weeks of 3D cardiac patch culture and carry important implications for future drug development and cell therapy studies.
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Affiliation(s)
- Donghui Zhang
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
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91
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Cosme J, Liu PP, Gramolini AO. The cardiovascular exosome: current perspectives and potential. Proteomics 2013; 13:1654-9. [PMID: 23526783 DOI: 10.1002/pmic.201200441] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 01/25/2013] [Accepted: 02/18/2013] [Indexed: 11/08/2022]
Abstract
The exosome is a secreted microvesicle that has been shown to contain genetic material and proteins and is involved in multiple levels of cellular communication. The cardiovascular exosome proteome is a promising subproteome that warrants investigation since a detailed understanding of its role in the heart should improve our comprehension of intercellular communication in the heart, and may even assist in biomarker discovery. Indeed, uncovering the role of the exosome in cardiovascular physiology could be accomplished with the application of scientific approaches and insights gained from studies of exosomes in other fields, such as cancer biology and immunology, where much of the established knowledge of the exosome has been generated. In the present review, we discuss the relevant literature and examine areas of investigation that would bring the cardiovascular exosome to the forefront of intercellular communication in the heart.
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Affiliation(s)
- Jake Cosme
- Department of Physiology, University of Toronto, Toronto, ON, Canada
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92
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Chang MG, de Lange E, Calmettes G, Garfinkel A, Qu Z, Weiss JN. Pro- and antiarrhythmic effects of ATP-sensitive potassium current activation on reentry during early afterdepolarization-mediated arrhythmias. Heart Rhythm 2013; 10:575-82. [PMID: 23246594 PMCID: PMC4285341 DOI: 10.1016/j.hrthm.2012.12.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Indexed: 11/26/2022]
Abstract
BACKGROUND Under conditions promoting early afterdepolarizations (EADs), ventricular tissue can become bi-excitable, that is, capable of wave propagation mediated by either the Na current (INa) or the L-type calcium current (ICa,L), raising the possibility that ICa,L-mediated reentry may contribute to polymorphic ventricular tachycardia (PVT) and torsades de pointes. ATP-sensitive K current (IKATP) activation suppresses EADs, but the effects on ICa,L-mediated reentry are unknown. OBJECTIVE To investigate the effects of IKATP activation on ICa,L-mediated reentry. METHODS We performed optical voltage mapping in cultured neonatal rat ventricular myocyte monolayers exposed to BayK8644 and isoproterenol. The effects of pharmacologically activating IKATP with pinacidil were analyzed. RESULTS In 13 monolayers with anatomic ICa,L-mediated reentry around a central obstacle, pinacidil (50 μM) converted ICa,L-mediated reentry to INa-mediated reentry. In 33 monolayers with functional ICa,L-mediated reentry (spiral waves), pinacidil terminated reentry in 17, converted reentry into more complex INa-mediated reentry resembling fibrillation in 12, and had no effect in 4. In simulated 2-dimensional bi-excitable tissue in which ICa,L- and INa-mediated wave fronts coexisted, slow IKATP activation (over minutes) reliably terminated rotors but rapid IKATP activation (over seconds) often converted ICa,L-mediated reentry to INa-mediated reentry resembling fibrillation. CONCLUSIONS IKATP activation can have proarrhythmic effects on EAD-mediated arrhythmias if ICa,L-mediated reentry is present.
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Affiliation(s)
- Marvin G. Chang
- Department of Medicine (Cardiology), David Geffen School of Medicine at University of California, Los Angeles, California
| | - Enno de Lange
- Department of Medicine (Cardiology), David Geffen School of Medicine at University of California, Los Angeles, California
| | - Guillaume Calmettes
- Department of Medicine (Cardiology), David Geffen School of Medicine at University of California, Los Angeles, California
| | - Alan Garfinkel
- Department of Medicine (Cardiology), David Geffen School of Medicine at University of California, Los Angeles, California
- Department of Integrative Biology and Physiology, David Geffen School of Medicine at University of California, Los Angeles, California
| | - Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine at University of California, Los Angeles, California
| | - James N. Weiss
- Department of Medicine (Cardiology), David Geffen School of Medicine at University of California, Los Angeles, California
- Department of Physiology, David Geffen School of Medicine at University of California, Los Angeles, California
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93
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Kaur K, Zarzoso M, Ponce-Balbuena D, Guerrero-Serna G, Hou L, Musa H, Jalife J. TGF-β1, released by myofibroblasts, differentially regulates transcription and function of sodium and potassium channels in adult rat ventricular myocytes. PLoS One 2013; 8:e55391. [PMID: 23393573 PMCID: PMC3564808 DOI: 10.1371/journal.pone.0055391] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 12/21/2012] [Indexed: 12/19/2022] Open
Abstract
Cardiac injury promotes fibroblasts activation and differentiation into myofibroblasts, which are hypersecretory of multiple cytokines. It is unknown whether any of such cytokines are involved in the electrophysiological remodeling of adult cardiomyocytes. We cultured adult cardiomyocytes for 3 days in cardiac fibroblast conditioned medium (FCM) from adult rats. In whole-cell voltage-clamp experiments, FCM-treated myocytes had 41% more peak inward sodium current (INa) density at −40 mV than myocytes in control medium (p<0.01). In contrast, peak transient outward current (Ito) was decreased by ∼55% at 60 mV (p<0.001). Protein analysis of FCM demonstrated that the concentration of TGF-β1 was >3 fold greater in FCM than control, which suggested that FCM effects could be mediated by TGF-β1. This was confirmed by pre-treatment with TGF-β1 neutralizing antibody, which abolished the FCM-induced changes in both INa and Ito. In current-clamp experiments TGF-β1 (10 ng/ml) prolonged the action potential duration at 30, 50, and 90 repolarization (p<0.05); at 50 ng/ml it gave rise to early afterdepolarizations. In voltage-clamp experiments, TGF-β1 increased INa density in a dose-dependent manner without affecting voltage dependence of activation or inactivation. INa density was −36.25±2.8 pA/pF in control, −59.17±6.2 pA/pF at 0.1 ng/ml (p<0.01), and −58.22±6.6 pA/pF at 1 ng/ml (p<0.01). In sharp contrast, Ito density decreased from 22.2±1.2 pA/pF to 12.7±0.98 pA/pF (p<0.001) at 10 ng/ml. At 1 ng/ml TGF-β1 significantly increased SCN5A (NaV1.5) (+73%; p<0.01), while reducing KCNIP2 (Kchip2; −77%; p<0.01) and KCND2 (KV4.2; −50% p<0.05) mRNA levels. Further, the TGF-β1-induced increase in INa was mediated through activation of the PI3K-AKT pathway via phosphorylation of FOXO1 (a negative regulator of SCN5A). TGF-β1 released by myofibroblasts differentially regulates transcription and function of the main cardiac sodium channel and of the channel responsible for the transient outward current. The results provide new mechanistic insight into the electrical remodeling associated with myocardial injury.
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Affiliation(s)
- Kuljeet Kaur
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Manuel Zarzoso
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Daniela Ponce-Balbuena
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Guadalupe Guerrero-Serna
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Luqia Hou
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Hassan Musa
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, United States of America
| | - José Jalife
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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94
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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: 96] [Impact Index Per Article: 8.0] [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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95
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Cardiac intercellular communication: are myocytes and fibroblasts fair-weather friends? J Cardiovasc Transl Res 2012; 5:768-82. [PMID: 23015462 DOI: 10.1007/s12265-012-9404-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Accepted: 08/20/2012] [Indexed: 10/27/2022]
Abstract
The cardiac fibroblast (CF) has historically been thought of as a quiescent cell of the heart, passively maintaining the extracellular environment for the cardiomyocytes (CM), the functional cardiac cell type. The increasingly appreciated role of the CF, however, extends well beyond matrix production, governing many aspects of cardiac function including cardiac electrophysiology and contractility. Importantly, its contributions to cardiac pathophysiology and pathologic remodeling have created a shift in the field's focus from the CM to the CF as a therapeutic target in the treatment of cardiac diseases. In response to cardiac injury, the CF undergoes a pathologic phenotypic transition into a myofibroblast, characterized by contractile smooth muscle proteins and upregulation of collagens, matrix proteins, and adhesion molecules. Further, the myofibroblast upregulates expression and secretion of a variety of pro-inflammatory, profibrotic mediators, including cytokines, chemokines, and growth factors. These mediators act in both an autocrine fashion to further activate CFs, as well as in a paracrine manner on both CMs and circulating inflammatory cells to induce myocyte dysfunction and chronic inflammation, respectively. Together, cell-specific cytokine-induced effects exacerbate pathologic remodeling and progression to HF. A better understanding of this dynamic intercellular communication will lead to novel targets for the attenuation of cardiac remodeling. Current strategies aimed at targeting cytokines have been largely unsuccessful in clinical trials, lending insights into ways that such intercellular cross talk can be more effectively attenuated. This review will summarize the current knowledge regarding CF functions in the heart and will discuss the regulation and signaling behind CF-mediated cytokine production and function. We will then highlight clinical trials that have exploited cytokine cross talk in the treatment of heart failure and provide novel strategies currently under investigation that may more effectively target pathologic CF-CM communication for the treatment of cardiac disease. This review explores novel mechanisms to directly attenuate heart failure progression through inhibition of signaling downstream of pro-inflammatory cytokines that are elevated after cardiac injury.
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96
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Vasquez C, Morley GE. The origin and arrhythmogenic potential of fibroblasts in cardiac disease. J Cardiovasc Transl Res 2012; 5:760-7. [PMID: 22987310 DOI: 10.1007/s12265-012-9408-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 08/29/2012] [Indexed: 12/11/2022]
Abstract
Fibroblasts play a major role in normal cardiac physiology and in the response of the heart to injury and disease. Cardiac electrophysiological research has primarily focused on the mechanisms of remodeling that accompany cardiac disease with an emphasis on myocyte electrophysiology. Recently, there has been increasing interest in the potential role of fibroblasts in cardiac electrophysiology. This review focuses on the arrhythmia mechanisms involving interactions between myocytes and fibroblasts. We also discuss the available evidence supporting the contribution of intracardiac and extracardiac sources to the fibroblast and myofibroblast populations in diseased hearts.
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Affiliation(s)
- Carolina Vasquez
- Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, 522 First Avenue, Smilow Building 8th Floor, New York, NY 10016, USA
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97
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Askar SFA, Bingen BO, Schalij MJ, Swildens J, Atsma DE, Schutte CI, de Vries AAF, Zeppenfeld K, Ypey DL, Pijnappels DA. Similar arrhythmicity in hypertrophic and fibrotic cardiac cultures caused by distinct substrate-specific mechanisms. Cardiovasc Res 2012; 97:171-81. [PMID: 22977008 DOI: 10.1093/cvr/cvs290] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Cardiac hypertrophy and fibrosis are associated with potentially lethal arrhythmias. As these substrates often occur simultaneously in one patient, distinguishing between pro-arrhythmic mechanisms is difficult. This hampers understanding of underlying pro-arrhythmic mechanisms and optimal treatment. This study investigates and compares arrhythmogeneity and underlying pro-arrhythmic mechanisms of either cardiac hypertrophy or fibrosis in in vitro models. METHODS AND RESULTS Fibrosis was mimicked by free myofibroblast (MFB) proliferation in neonatal rat ventricular monolayers. Cultures with inhibited MFB proliferation were used as control or exposed to phenylephrine to induce hypertrophy. At Day 9, cultures were studied with patch-clamp and optical-mapping techniques and assessed for protein expression. In hypertrophic (n = 111) and fibrotic cultures (n = 107), conduction and repolarization were slowed. Triggered activity was commonly found in these substrates and led to high incidences of spontaneous re-entrant arrhythmias [67.5% hypertrophic, 78.5% fibrotic vs. 2.9% in controls (n = 102)] or focal arrhythmias (39.1, 51.7 vs. 8.8%, respectively). Kv4.3 and Cx43 protein expression levels were decreased in hypertrophy but unaffected in fibrosis. Depolarization of cardiomyocytes (CMCs) was only found in fibrotic cultures (-48 ± 7 vs. -66 ± 7 mV in control, P < 0.001). L-type calcium-channel blockade prevented arrhythmias in hypertrophy, but caused conduction block in fibrosis. Targeting heterocellular coupling by low doses of gap-junction uncouplers prevented arrhythmias by accelerating repolarization only in fibrotic cultures. CONCLUSION Cultured hypertrophic or fibrotic myocardial tissues generated similar focal and re-entrant arrhythmias. These models revealed electrical remodelling of CMCs as a pro-arrhythmic mechanism of hypertrophy and MFB-induced depolarization of CMCs as a pro-arrhythmic mechanism of fibrosis. These findings provide novel mechanistic insight into substrate-specific arrhythmicity.
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Affiliation(s)
- Saïd F A Askar
- Laboratory of Experimental Cardiology, Department of Cardiology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
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98
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Nguyen PD, Hsiao ST, Sivakumaran P, Lim SY, Dilley RJ. Enrichment of neonatal rat cardiomyocytes in primary culture facilitates long-term maintenance of contractility in vitro. Am J Physiol Cell Physiol 2012; 303:C1220-8. [PMID: 22932682 DOI: 10.1152/ajpcell.00449.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Long-term culture of primary neonatal rat cardiomyocytes is limited by the loss of spontaneous contractile phenotype within weeks in culture. This may be due to loss of contractile cardiomyocytes from the culture or overgrowth of the non-cardiomyocyte population. Using the mitochondria specific fluorescent dye, tetramethylrhodamine methyl ester perchlorate (TMRM), we showed that neonatal rat cardiomyocytes enriched by fluorescence-activated cell sorting can be maintained as contractile cultures for long periods (24-wk culture vs. 2 wk for unsorted cardiomyocytes). Long-term culture of this purified cardiomyocyte (TMRM high) population retained the expression of cardiomyocyte markers, continued calcium cycling, and displayed cyclic electrical activity that could be regulated pharmacologically. These findings suggest that non-cardiomyocyte populations can negatively influence contractility of cardiomyocytes in culture and that by purifying cardiomyocytes, the cultures retain potential as an experimental model for longitudinal studies of cardiomyocyte biology in vitro.
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Affiliation(s)
- Phong D Nguyen
- O’Brien Institute and University of Melbourne, Department of Surgery, St Vincent’s Hospital, Victoria, Australia
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99
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100
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McSpadden LC, Nguyen H, Bursac N. Size and ionic currents of unexcitable cells coupled to cardiomyocytes distinctly modulate cardiac action potential shape and pacemaking activity in micropatterned cell pairs. Circ Arrhythm Electrophysiol 2012; 5:821-30. [PMID: 22679057 DOI: 10.1161/circep.111.969329] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Cardiac cell therapies can yield electric coupling of unexcitable donor cells to host cardiomyocytes with functional consequences that remain unexplored. METHODS AND RESULTS We micropatterned cell pairs consisting of a neonatal rat ventricular myocyte (NRVM) coupled to an engineered human embryonic kidney 293 (HEK293) cell expressing either connexin-43 (Cx43 HEK) or inward rectifier potassium channel 2.1 (Kir2.1) and Cx43 (Kir2.1+Cx43 HEK). The NRVM-HEK contact length was fixed yielding a coupling strength of 68.9±9.7 nS, whereas HEK size was systematically varied. With increase in Cx43 HEK size, NRVM maximal diastolic potential was reduced from -71.7±0.6 mV in single NRVMs to -35.1±1.3 mV in pairs with an HEK:NRVM cell surface area ratio of 1.7±0.1, whereas the action potential upstroke ([dV(m)/dt](max)) and duration decreased to 1.6±0.7% and increased to 177±32% in single NRVM values, respectively (n=21 cell pairs). Pacemaking occurred in all NRVM-Cx43 HEK pairs with cell surface area ratios of 1.1 to 1.9. In contrast, NRVMs, coupled with Kir2.1+Cx43 HEKs of increasing size, had similar maximal diastolic potentials, exhibited no spontaneous activity, and showed a gradual decrease in action potential duration (n=23). Furthermore, coupling single NRVMs to a dynamic clamp model of HEK cell ionic current reproduced the cardiac maximal diastolic potentials and pacemaking rates recorded in cell pairs, whereas reproducing changes in (dV(m)/dt)(max) and action potential duration required coupling to an HEK model that also included cell membrane capacitance. CONCLUSIONS Size and ionic currents of unexcitable cells electrically coupled to cardiomyocytes distinctly affect cardiac action potential shape and initiation with important implications for the safety of cardiac cell and gene therapies.
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Affiliation(s)
- Luke C McSpadden
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
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