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Tran P, Linekar A, Dandekar U, Barker T, Balasubramanian S, Bhaskara-Pillai J, Shelley S, Maddock H, Banerjee P. Profiling the Biomechanical Responses to Workload on the Human Myocyte to Explore the Concept of Myocardial Fatigue and Reversibility: Rationale and Design of the POWER Heart Failure Study. J Cardiovasc Transl Res 2024; 17:275-286. [PMID: 37126208 PMCID: PMC10150683 DOI: 10.1007/s12265-023-10391-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 04/20/2023] [Indexed: 05/02/2023]
Abstract
It remains unclear why some patients develop heart failure without evidence of structural damage. One theory relates to impaired myocardial energetics and ventricular-arterial decoupling as the heart works against adverse mechanical load. In this original study, we propose the novel concept of myocardial fatigue to capture this phenomenon and aim to investigate this using human cardiomyocytes subjected to a modern work-loop contractility model that closely mimics in vivo cardiac cycles. This proof-of-concept study (NCT04899635) will use human myocardial tissue samples from patients undergoing cardiac surgery to develop a reproducible protocol to isolate robust calcium-tolerant cardiomyocytes. Thereafter, work-loop contractility experiments will be performed over a range of preload, afterload and cycle frequency as a function of time to elicit any reversible reduction in contractile performance (i.e. fatigue). This will provide novel insight into mechanisms behind heart failure and myocardial recovery and serve as a valuable research platform in translational cardiovascular research.
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Affiliation(s)
- Patrick Tran
- Centre for Sport, Exercise & Life Sciences, Faculty of Health & Life Sciences, Coventry University, Coventry, UK.
- Cardiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry, UK.
| | - Adam Linekar
- Centre for Sport, Exercise & Life Sciences, Faculty of Health & Life Sciences, Coventry University, Coventry, UK
- InoCardia Ltd, TechnoCentre, Puma Way, Coventry, UK
| | - Uday Dandekar
- Cardiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry, UK
- Warwick Medical School, University of Warwick, Coventry, UK
| | - Thomas Barker
- Centre for Sport, Exercise & Life Sciences, Faculty of Health & Life Sciences, Coventry University, Coventry, UK
- Cardiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry, UK
- Warwick Medical School, University of Warwick, Coventry, UK
| | - Sendhil Balasubramanian
- Cardiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry, UK
- Warwick Medical School, University of Warwick, Coventry, UK
| | - Jain Bhaskara-Pillai
- Cardiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry, UK
- Warwick Medical School, University of Warwick, Coventry, UK
| | - Sharn Shelley
- Centre for Sport, Exercise & Life Sciences, Faculty of Health & Life Sciences, Coventry University, Coventry, UK
- InoCardia Ltd, TechnoCentre, Puma Way, Coventry, UK
| | - Helen Maddock
- Centre for Sport, Exercise & Life Sciences, Faculty of Health & Life Sciences, Coventry University, Coventry, UK
- InoCardia Ltd, TechnoCentre, Puma Way, Coventry, UK
| | - Prithwish Banerjee
- Centre for Sport, Exercise & Life Sciences, Faculty of Health & Life Sciences, Coventry University, Coventry, UK
- Cardiology Department, University Hospitals Coventry and Warwickshire NHS Trust, Clifford Bridge Road, Coventry, UK
- Warwick Medical School, University of Warwick, Coventry, UK
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Gao S, Sun H, Chen K, Gu X, Chen H, Jiang L, Chen L, Zhang S, Liu Y, Shi D, Liang D, Xu L, Yang J, Ruan Y, Chen H, Shen B, Ma H, Chen YH. Depletion of m 6 A reader protein YTHDC1 induces dilated cardiomyopathy by abnormal splicing of Titin. J Cell Mol Med 2021; 25:10879-10891. [PMID: 34716659 PMCID: PMC8642692 DOI: 10.1111/jcmm.16955] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 09/08/2021] [Accepted: 09/19/2021] [Indexed: 12/01/2022] Open
Abstract
N6 -methyladenosine (m6 A) is the most prevalent modification in mRNA and engages in multiple biological processes. Previous studies indicated that m6 A methyltransferase METTL3 ('writer') and demethylase FTO ('eraser') play critical roles in heart-related disease. However, in the heart, the function of m6 A 'reader', such as YTH (YT521-B homology) domain-containing proteins remains unclear. Here, we report that the defect in YTHDC1 but not other YTH family members contributes to dilated cardiomyopathy (DCM) in mice. Cardiac-specific conditional Ythdc1 knockout led to obvious left ventricular chamber enlargement and severe systolic dysfunction. YTHDC1 deficiency also resulted in the decrease of cardiomyocyte contractility and disordered sarcomere arrangement. By means of integrating multiple high-throughput sequence technologies, including m6 A-MeRIP, RIP-seq and mRNA-seq, we identified 42 transcripts as potential downstream targets of YTHDC1. Amongst them, we found that Titin mRNA was decorated with m6 A modification and depletion of YTHDC1 resulted in aberrant splicing of Titin. Our study suggests that Ythdc1 plays crucial role in regulating the normal contractile function and the development of DCM. These findings clarify the essential role of m6 A reader in cardiac biofunction and provide a novel potential target for the treatment of DCM.
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Affiliation(s)
- Siyun Gao
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Haifeng Sun
- State Key Laboratory of Reproductive Medicine, Center for Global Health, Gusu School, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Hospital, Nanjing Medical University, Nanjing, China
| | - Kejing Chen
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Xueying Gu
- State Key Laboratory of Reproductive Medicine, Center for Global Health, Gusu School, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Hospital, Nanjing Medical University, Nanjing, China
| | - Hongyu Chen
- State Key Laboratory of Reproductive Medicine, Center for Global Health, Gusu School, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Hospital, Nanjing Medical University, Nanjing, China
| | - Liudan Jiang
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Lei Chen
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Shengqi Zhang
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yi Liu
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
| | - Dan Shi
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Dandan Liang
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Liang Xu
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China
| | - Jian Yang
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
| | - Yanjiao Ruan
- School of Medicine, Southern University of Science and Technology, Shenzhen, China
| | - Hao Chen
- School of Medicine, Southern University of Science and Technology, Shenzhen, China
| | - Bin Shen
- State Key Laboratory of Reproductive Medicine, Center for Global Health, Gusu School, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Hospital, Nanjing Medical University, Nanjing, China
| | - Honghui Ma
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China.,Research Units of Origin and Regulation of Heart Rhythm, Chinese Academy of Medical Sciences, Shanghai, China
| | - Yi-Han Chen
- Department of Cardiology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China.,Institute of Medical Genetics, Tongji University, Shanghai, China.,Department of Pathology and Pathophysiology, Tongji University School of Medicine, Shanghai, China
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3
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Multiparametric Mechanistic Profiling of Inotropic Drugs in Adult Human Primary Cardiomyocytes. Sci Rep 2020; 10:7692. [PMID: 32376974 PMCID: PMC7203129 DOI: 10.1038/s41598-020-64657-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 04/10/2020] [Indexed: 01/10/2023] Open
Abstract
Effects of non-cardiac drugs on cardiac contractility can lead to serious adverse events. Furthermore, programs aimed at treating heart failure have had limited success and this therapeutic area remains a major unmet medical need. The challenges in assessing drug effect on cardiac contractility point to the fundamental translational value of the current preclinical models. Therefore, we sought to develop an adult human primary cardiomyocyte contractility model that has the potential to provide a predictive preclinical approach for simultaneously predicting drug-induced inotropic effect (sarcomere shortening) and generating multi-parameter data to profile different mechanisms of action based on cluster analysis of a set of 12 contractility parameters. We report that 17 positive and 9 negative inotropes covering diverse mechanisms of action exerted concentration-dependent increases and decreases in sarcomere shortening, respectively. Interestingly, the multiparametric readout allowed for the differentiation of inotropes operating via distinct mechanisms. Hierarchical clustering of contractility transient parameters, coupled with principal component analysis, enabled the classification of subsets of both positive as well as negative inotropes, in a mechanism-related mode. Thus, human cardiomyocyte contractility model could accurately facilitate informed mechanistic-based decision making, risk management and discovery of molecules with the most desirable pharmacological profile for the correction of heart failure.
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Sun H, Zhou J, Huang Z, Qu L, Lin N, Liang C, Dai R, Tang L, Tian F. Carbon nanotube-incorporated collagen hydrogels improve cell alignment and the performance of cardiac constructs. Int J Nanomedicine 2017; 12:3109-3120. [PMID: 28450785 PMCID: PMC5399986 DOI: 10.2147/ijn.s128030] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Carbon nanotubes (CNTs) provide an essential 2-D microenvironment for cardiomyocyte growth and function. However, it remains to be elucidated whether CNT nanostructures can promote cell–cell integrity and facilitate the formation of functional tissues in 3-D hydrogels. Here, single-walled CNTs were incorporated into collagen hydrogels to fabricate (CNT/Col) hydrogels, which improved mechanical and electrical properties. The incorporation of CNTs (up to 1 wt%) exhibited no toxicity to cardiomyocytes and enhanced cell adhesion and elongation. Through the use of immunohistochemical staining, transmission electron microscopy, and intracellular calcium-transient measurement, the incorporation of CNTs was found to improve cell alignment and assembly remarkably, which led to the formation of engineered cardiac tissues with stronger contraction potential. Importantly, cardiac tissues based on CNT/Col hydrogels were noted to have better functionality. Collectively, the incorporation of CNTs into the Col hydrogels improved cell alignment and the performance of cardiac constructs. Our study suggests that CNT/Col hydrogels offer a promising tissue scaffold for cardiac constructs, and might serve as injectable biomaterials to deliver cell or drug molecules for cardiac regeneration following myocardial infarction in the near future.
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Affiliation(s)
- Hongyu Sun
- General Surgery Center, Chengdu Military General Hospital, Chengdu, China
| | - Jing Zhou
- General Surgery Center, Chengdu Military General Hospital, Chengdu, China
| | - Zhu Huang
- General Surgery Center, Chengdu Military General Hospital, Chengdu, China
| | - Linlin Qu
- General Surgery Center, Chengdu Military General Hospital, Chengdu, China
| | - Ning Lin
- General Surgery Center, Chengdu Military General Hospital, Chengdu, China
| | - Chengxiao Liang
- General Surgery Center, Chengdu Military General Hospital, Chengdu, China
| | - Ruiwu Dai
- General Surgery Center, Chengdu Military General Hospital, Chengdu, China
| | - Lijun Tang
- General Surgery Center, Chengdu Military General Hospital, Chengdu, China
| | - Fuzhou Tian
- General Surgery Center, Chengdu Military General Hospital, Chengdu, China
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5
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Lundy SD, Zhu WZ, Regnier M, Laflamme MA. Structural and functional maturation of cardiomyocytes derived from human pluripotent stem cells. Stem Cells Dev 2013; 22:1991-2002. [PMID: 23461462 DOI: 10.1089/scd.2012.0490] [Citation(s) in RCA: 534] [Impact Index Per Article: 48.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Despite preclinical studies demonstrating the functional benefit of transplanting human pluripotent stem cell-derived cardiomyocytes (PSC-CMs) into damaged myocardium, the ability of these immature cells to adopt a more adult-like cardiomyocyte (CM) phenotype remains uncertain. To address this issue, we tested the hypothesis that prolonged in vitro culture of human embryonic stem cell (hESC)- and human induced pluripotent stem cell (hiPSC)-derived CMs would result in the maturation of their structural and contractile properties to a more adult-like phenotype. Compared to their early-stage counterparts (PSC-CMs after 20-40 days of in vitro differentiation and culture), late-stage hESC-CMs and hiPSC-CMs (80-120 days) showed dramatic differences in morphology, including increased cell size and anisotropy, greater myofibril density and alignment, sarcomeres visible by bright-field microscopy, and a 10-fold increase in the fraction of multinucleated CMs. Ultrastructural analysis confirmed improvements in the myofibrillar density, alignment, and morphology. We measured the contractile performance of late-stage hESC-CMs and hiPSC-CMs and noted a doubling in shortening magnitude with slowed contraction kinetics compared to the early-stage cells. We then examined changes in the calcium-handling properties of these matured CMs and found an increase in calcium release and reuptake rates with no change in the maximum amplitude. Finally, we performed electrophysiological assessments in hESC-CMs and found that late-stage myocytes have hyperpolarized maximum diastolic potentials, increased action potential amplitudes, and faster upstroke velocities. To correlate these functional changes with gene expression, we performed qPCR and found a robust induction of the key cardiac structural markers, including β-myosin heavy chain and connexin-43, in late-stage hESC-CMs and hiPSC-CMs. These findings suggest that PSC-CMs are capable of slowly maturing to more closely resemble the phenotype of adult CMs and may eventually possess the potential to regenerate the lost myocardium with robust de novo force-producing tissue.
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Affiliation(s)
- Scott D Lundy
- Departments of Bioengineering, University of Washington, Seattle, Washington, USA
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6
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Maffit SK, Sellitto AD, Al-Dadah AS, Schuessler RB, Damiano RJ, Lawton JS. Diazoxide maintains human myocyte volume homeostasis during stress. J Am Heart Assoc 2012; 1:jah312. [PMID: 23130119 PMCID: PMC3487366 DOI: 10.1161/jaha.112.000778] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 02/14/2012] [Indexed: 11/30/2022]
Abstract
Background Exposure to hypothermic hyperkalemic cardioplegia, hyposmotic stress, or metabolic inhibition results in significant animal myocyte swelling (6% to10%) and subsequent reduced contractility (10% to 20%). Both are eliminated by the adenosine triphosphate-sensitive potassium channel opener diazoxide (DZX). The relationship between swelling and reduced contractility suggests that the structural change may represent one mechanism of postoperative myocardial stunning. This study evaluated human myocyte volume during stress to investigate if similar phenomena exist in human myocytes. Methods and Results Human atrial myocytes isolated from tissue obtained during cardiac surgery were perfused with Tyrode's physiological solution (20 minutes, 37°C), test solution (20 minutes), and Tyrode's (37°C, 20 minutes). Test solutions (n=6 to 12 myocytes each) included Tyrode's (37°C or 9°C), Tyrode's+DZX (9°C), hyperkalemic cardioplegia (9°C)±DZX, cardioplegia+DZX+HMR 1098 (sarcolemmal adenosine triphosphate-sensitive potassium channel inhibitor, 9°C), cardioplegia+DZX+5-hydroxydeconoate (mitochondrial adenosine triphosphate-sensitive potassium channel inhibitor, 9°C), mild hyposmotic solution±DZX, metabolic inhibition±DZX, and metabolic inhibition+DZX+5-hydroxydeconoate. Myocyte volume was recorded every 5 minutes. Exposure to hypothermic hyperkalemic cardioplegia, hyposmotic stress, or metabolic inhibition resulted in significant human myocyte swelling (8%, 7%, and 6%, respectively; all P<0.05 vs control). In all groups, the swelling was eliminated or lessened by DZX. The addition of channel inhibitors did not significantly alter results. Conclusions DZX maintains human myocyte volume homeostasis during stress via an unknown mechanism. DZX may prove to be clinically useful following the elucidation of its specific mechanism of action. (J Am Heart Assoc. 2012;1:jah3-e000778 doi: 10.1161/JAHA.112.000778.)
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Affiliation(s)
- Sara K Maffit
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, MO
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7
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Spruill LS, Lowry AS, Stroud RE, Squires CE, Mains IM, Flack EC, Beck C, Ikonomidis JS, Crumbley AJ, McDermott PJ, Spinale FG. Membrane-type-1 matrix metalloproteinase transcription and translation in myocardial fibroblasts from patients with normal left ventricular function and from patients with cardiomyopathy. Am J Physiol Cell Physiol 2007; 293:C1362-73. [PMID: 17670887 DOI: 10.1152/ajpcell.00545.2006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Past studies have identified that a unique type of matrix metalloproteinase, the membrane-type-1 MMP (MT1-MMP), is increased within the left ventricle (LV) of patients with dilated cardiomyopathy (DCM). However, the cellular and molecular basis for this induction of MT1-MMP with DCM is unknown. LV myocardial biopsies from nonfailing, reference normal patients (defined as LV ejection fraction >50%, elective coronary bypass surgery, no perfusion defect at biopsy site, n = 6) and DCM patients (LV ejection fraction <20%, at transplant, n = 5) were used to establish fibroblast cultures (FIBROS). Confluent LV FIBROS from culture passages 2-5 were measured with respect to MT1-MMP mRNA and protein levels and the distribution of the MT1-MMP mRNA pool in ribosomal fractions. Total MT1-MMP mRNA within DCM FIBROS increased by over 140%, and MT1-MMP protein increased by over 190% from reference normal FIBROS (both P < 0.05). MT1-MMP mRNA in monosome fractions decreased by over twofold in DCM FIBROS compared with reference normal (P < 0.05) and remained lower in polyribosomal fractions (i.e., 15.7 +/- 5.2 vs. 1.4 +/- 0.6% in polysomal fraction 6, P < 0.05). These differences in DCM MT1-MMP FIBROS transcription and translation persisted throughout passages 2-5. The unique findings from this study demonstrated that elevated steady-state MT1-MMP mRNA and protein levels occurred in DCM FIBROS despite a decline in translational deficiency. These phenotypic changes in DCM fibroblasts may provide the basis for developing cell specific pharmacological targets for control of MT1-MMP expression.
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Affiliation(s)
- Laura S Spruill
- Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, USA
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Kovacs A, Courtois MR, Weinheimer CJ, Posdamer SH, Wallace KD, Holland MR, Miller JG. Ultrasonic tissue characterization of the mouse myocardium: Successful in vivo cyclic variation measurements. J Am Soc Echocardiogr 2004; 17:883-92. [PMID: 15282494 DOI: 10.1016/j.echo.2004.04.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Measurements of the systematic variation of backscattered ultrasonic energy from myocardium during the heart cycle (cyclic variation) have been successfully used to characterize a wide spectrum of cardiac pathologies in large animal models and human subjects. The purpose of this study was to evaluate the feasibility of extending cyclic variation measurements to the study of genetically manipulated mouse models of cardiac diseases as a method for developing further insights into the disease-altered properties of the myocardium and its characterization with ultrasound. METHODS Parasternal long-axis images of the heart were obtained in 9 wild-type mice under light anesthesia using a commercial imaging system with a 15-MHz nominal center frequency linear array. Images of a tissue-mimicking phantom and the mouse hearts were obtained for a series of specific receiver gains for each of a series of specific dynamic range settings. Analyses of these data formed the basis for gray-scale image calibration. Cyclic variation measurements were obtained by determining the average gray-scale value for a region of interest placed in the midmyocardium of the posterior wall for each frame acquired during 4 cardiac cycles and converting these mean gray-scale values to backscatter values expressed in decibels using the determined calibration. Results are expressed in terms of the magnitude and time delay of cyclic variation. To evaluate repeatability of these measurements the same group of mice underwent the identical imaging protocol 2 weeks after the first study. RESULTS The mean magnitude of cyclic variation was found to be 4.6 +/- 0.2 dB with a corresponding normalized time delay of 1.02 +/- 0.03 for data averaged over all dynamic range settings. There was no significant difference among results obtained with each of the dynamic range settings. A comparison of these results with those from data acquired 2 weeks after the initial study showed no significant difference. CONCLUSION This study represents the first reported measurement of cyclic variation in mice and demonstrates that reliable cyclic variation measurements can be obtained among individual animals and over different time points and, hence, forms the basis for subsequent investigations addressing specific cardiac pathologies and effects arising from myocardial anisotropy.
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Affiliation(s)
- Attila Kovacs
- Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Spinale FG, Coker ML, Heung LJ, Bond BR, Gunasinghe HR, Etoh T, Goldberg AT, Zellner JL, Crumbley AJ. A matrix metalloproteinase induction/activation system exists in the human left ventricular myocardium and is upregulated in heart failure. Circulation 2000; 102:1944-9. [PMID: 11034943 DOI: 10.1161/01.cir.102.16.1944] [Citation(s) in RCA: 307] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Matrix metalloproteinases (MMPs) contribute to matrix remodeling in disease states such as tumor metastases. Extracellular matrix metalloproteinase inducer (EMMPRIN) has been reported to increase MMP expression, and membrane-type MMP or MT1-MMP has been implicated to activate MMPs. The present study examined whether and to what degree EMMPRIN and MT1-MMP were expressed in human left ventricular (LV) myocardium as well as the association with MMP activity and expression in dilated cardiomyopathy (DCM). METHODS AND RESULTS LV myocardial zymographic MMP activity increased by >2-fold with both nonischemic DCM (n=21) and ischemic DCM (n=16) compared with normal (n=13). LV myocardial abundance of MMP-9 was increased with both forms of DCM. MMP-2 and MMP-3 were increased with nonischemic DCM. MMP-1 levels were decreased with both forms of DCM. EMMPRIN increased by >250% and MT1-MMP increased by >1000% with both forms of DCM. CONCLUSIONS Increased LV myocardial MMP activity and selective upregulation of MMPs with nonischemic and ischemic forms of DCM occurred. Moreover, a local MMP induction/activation system was identified in isolated normal human LV myocytes that was upregulated with DCM. The control of MMP activation and expression in the failing human LV myocardium represents a new and potentially significant therapeutic target for this disease process.
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Affiliation(s)
- F G Spinale
- Medical University of South Carolina, Charleston 29425, USA
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10
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Goldberg AT, Bond BR, Mukherjee R, New RB, Zellner JL, Crawford FA, Spinale FG. Endothelin receptor pathway in human left ventricular myocytes: relation to contractility. Ann Thorac Surg 2000; 69:711-5; discussion 716. [PMID: 10750748 DOI: 10.1016/s0003-4975(99)01515-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Increased synthesis and release of the potent bioactive peptide endothelin-1 (ET-1) occurs during and after cardiac surgery. However, the cellular and molecular basis for the effects of ET-1 on human left ventricular (LV) myocyte contractility remains unknown. METHODS LV myocyte contractility was examined from myocardial biopsies taken from patients (n = 30) undergoing elective coronary artery bypass. LV myocytes (n = 997, > 30/patient) were isolated using microtrituration and contractility examined by videomicroscopy at baseline and after ET-1 exposure (200 pmol/L). In additional studies, myocytes were pretreated to inhibit either protein kinase C (PKC) (chelerythrine, 1 micromol/L), the sodium/hydrogen (Na/H) exchanger (EIPA, 1 micromol/L), both PKC and the Na/H exchanger, or the ET(A) receptor (BQ-123, 1 micromol/L), followed with ET-1 exposure. RESULTS Basal myocyte shortening increased 37.8 +/- 6.3% with ET-1 (p < 0.05). Na/H exchanger, PKC, and dual inhibition all eliminated the effects of ET-1. Furthermore, ET(A) inhibition demonstrated that ET-1 effects on myocyte contractility were mediated through the ET(A) receptor subtype. CONCLUSIONS ET-1 directly influences human LV myocyte contractility, which is mediated through the ET(A) receptor and requires intracellular activation of PKC and stimulation of the Na/H exchanger.
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Affiliation(s)
- A T Goldberg
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston 29403, USA
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11
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Walker CA, Spinale FG. The structure and function of the cardiac myocyte: a review of fundamental concepts. J Thorac Cardiovasc Surg 1999; 118:375-82. [PMID: 10425017 DOI: 10.1016/s0022-5223(99)70233-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- C A Walker
- Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston, SC, USA
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