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Corradi F, Masini G, Bucciarelli T, De Caterina R. Iron deficiency in myocardial ischaemia: molecular mechanisms and therapeutic perspectives. Cardiovasc Res 2023; 119:2405-2420. [PMID: 37722377 DOI: 10.1093/cvr/cvad146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 05/14/2023] [Accepted: 07/10/2023] [Indexed: 09/20/2023] Open
Abstract
Systemic iron deficiency (SID), even in the absence of anaemia, worsens the prognosis and increases mortality in heart failure (HF). Recent clinical-epidemiological studies, however, have shown that a myocardial iron deficiency (MID) is frequently present in cases of severe HF, even in the absence of SID and without anaemia. In addition, experimental studies have shown a poor correlation between the state of systemic and myocardial iron. MID in animal models leads to severe mitochondrial dysfunction, alterations of mitophagy, and mitochondrial biogenesis, with profound alterations in cardiac mechanics and the occurrence of a fatal cardiomyopathy, all effects prevented by intravenous administration of iron. This shifts the focus to the myocardial state of iron, in the absence of anaemia, as an important factor in prognostic worsening and mortality in HF. There is now epidemiological evidence that SID worsens prognosis and mortality also in patients with acute and chronic coronary heart disease and experimental evidence that MID aggravates acute myocardial ischaemia as well as post-ischaemic remodelling. Intravenous administration of ferric carboxymaltose (FCM) or ferric dextrane improves post-ischaemic adverse remodelling. We here review such evidence, propose that MID worsens ischaemia/reperfusion injury, and discuss possible molecular mechanisms, such as chronic hyperactivation of HIF1-α, exacerbation of cytosolic and mitochondrial calcium overload, amplified increase of mitochondrial [NADH]/[NAD+] ratio, and depletion of energy status and NAD+ content with inhibition of sirtuin 1-3 activity. Such evidence now portrays iron metabolism as a core factor not only in HF but also in myocardial ischaemia.
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Affiliation(s)
- Francesco Corradi
- Department of Medicine and Aging Sciences, "G. D'Annunzio" University of Chieti-Pescara, Via dei Vestini, 66100, Chieti, Italy
| | - Gabriele Masini
- Chair and Postgraduate School of Cardiology, University of Pisa, Via Savi 10, 56126, Pisa, Italy
| | - Tonino Bucciarelli
- Department of Medicine and Aging Sciences, "G. D'Annunzio" University of Chieti-Pescara, Via dei Vestini, 66100, Chieti, Italy
| | - Raffaele De Caterina
- Chair and Postgraduate School of Cardiology, University of Pisa, Via Savi 10, 56126, Pisa, Italy
- Fondazione VillaSerena per la Ricerca, Viale L. Petruzzi 42, 65013, Città Sant'Angelo, Pescara, Italy
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Corrado PA, Barton GP, Razalan-Krause FC, François CJ, Chesler NC, Wieben O, Eldridge M, McMillan AB, Goss KN. Dynamic FDG PET Imaging to Probe for Cardiac Metabolic Remodeling in Adults Born Premature. J Clin Med 2021; 10:1301. [PMID: 33809883 PMCID: PMC8004130 DOI: 10.3390/jcm10061301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 03/17/2021] [Accepted: 03/19/2021] [Indexed: 11/20/2022] Open
Abstract
Individuals born very premature have an increased cardiometabolic and heart failure risk. While the structural differences of the preterm heart are now well-described, metabolic insights into the physiologic mechanisms underpinning this risk are needed. Here, we used dynamic fluorodeoxyglucose (FDG) positron emission tomography/magnetic resonance imaging (PET-MRI) in young adults born term and preterm during normoxic (N = 28 preterm; 18 term) and hypoxic exposure (12% O2; N = 26 preterm; 17 term) to measure the myocardial metabolic rate of glucose (MMRglc) in young adults born term (N = 18) and preterm (N = 32), hypothesizing that young adults born preterm would have higher rates of MMRglc under normoxic conditions and a reduced ability to augment glucose metabolism under hypoxic conditions. MMRglc was calculated from the myocardial and blood pool time-activity curves by fitting the measured activities to the 3-compartment model of FDG kinetics. MMRglc was similar at rest between term and preterm subjects, and decreased during hypoxia exposure in both groups (p = 0.02 for MMRglc hypoxia effect). There were no differences observed between groups in the metabolic response to hypoxia, either globally (serum glucose and lactate measures) or within the myocardium. Thus, we did not find evidence of altered myocardial metabolism in the otherwise healthy preterm-born adult. However, whether subtle changes in myocardial metabolism may preceed or predict heart failure in this population remains to be determined.
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Affiliation(s)
- Philip A. Corrado
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA; (P.A.C.); (G.P.B.); (O.W.); (A.B.M.)
| | - Gregory P. Barton
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA; (P.A.C.); (G.P.B.); (O.W.); (A.B.M.)
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53705, USA;
| | | | | | - Naomi C. Chesler
- Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, CA 92697, USA;
- Department of Biomedical Engineering, University of California, Irvine, CA 92697, USA
| | - Oliver Wieben
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA; (P.A.C.); (G.P.B.); (O.W.); (A.B.M.)
- Department of Radiology, University of Wisconsin-Madison, Madison, WI 53705, USA;
| | - Marlowe Eldridge
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53705, USA;
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA;
| | - Alan B. McMillan
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA; (P.A.C.); (G.P.B.); (O.W.); (A.B.M.)
- Department of Radiology, University of Wisconsin-Madison, Madison, WI 53705, USA;
| | - Kara N. Goss
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53705, USA;
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA;
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3
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Affiliation(s)
- Robert A. Kloner
- Huntington Medical Research InstitutesPasadenaCA
- Division of Cardiovascular MedicineDepartment of MedicineKeck School of Medicine at University of Southern CaliforniaLos AngelesCA
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4
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Hammarsten O, Mair J, Möckel M, Lindahl B, Jaffe AS. Possible mechanisms behind cardiac troponin elevations. Biomarkers 2018; 23:725-734. [DOI: 10.1080/1354750x.2018.1490969] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Ola Hammarsten
- Department of Clinical Chemistry and Transfusion Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Johannes Mair
- Department of Internal Medicine III – Cardiology and Angiology, Heart Center, Medical University of Innsbruck, Innsbruck, Austria
| | - Martin Möckel
- Division of Emergency Medicine and Department of Cardiology, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Bertil Lindahl
- Department of Medical Sciences, Uppsala University and Uppsala Clinical Research Center, Uppsala, Sweden
| | - Allan S. Jaffe
- Department of Cardiovascular Medicine, Mayo Clinic and Medical School, Rochester, MN, USA
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5
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Abstract
Ischemic disorders, such as myocardial infarction, stroke, and peripheral vascular disease, are the most common causes of debilitating disease and death in westernized cultures. The extent of tissue injury relates directly to the extent of blood flow reduction and to the length of the ischemic period, which influence the levels to which cellular ATP and intracellular pH are reduced. By impairing ATPase-dependent ion transport, ischemia causes intracellular and mitochondrial calcium levels to increase (calcium overload). Cell volume regulatory mechanisms are also disrupted by the lack of ATP, which can induce lysis of organelle and plasma membranes. Reperfusion, although required to salvage oxygen-starved tissues, produces paradoxical tissue responses that fuel the production of reactive oxygen species (oxygen paradox), sequestration of proinflammatory immunocytes in ischemic tissues, endoplasmic reticulum stress, and development of postischemic capillary no-reflow, which amplify tissue injury. These pathologic events culminate in opening of mitochondrial permeability transition pores as a common end-effector of ischemia/reperfusion (I/R)-induced cell lysis and death. Emerging concepts include the influence of the intestinal microbiome, fetal programming, epigenetic changes, and microparticles in the pathogenesis of I/R. The overall goal of this review is to describe these and other mechanisms that contribute to I/R injury. Because so many different deleterious events participate in I/R, it is clear that therapeutic approaches will be effective only when multiple pathologic processes are targeted. In addition, the translational significance of I/R research will be enhanced by much wider use of animal models that incorporate the complicating effects of risk factors for cardiovascular disease. © 2017 American Physiological Society. Compr Physiol 7:113-170, 2017.
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Affiliation(s)
- Theodore Kalogeris
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, USA
| | - Christopher P. Baines
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA
- Department of Biomedical Sciences, University of Missouri College of Veterinary Medicine, Columbia, Missouri, USA
| | - Maike Krenz
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA
| | - Ronald J. Korthuis
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA
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McCormick ME, Rojas M, Moser-Katz T, Tzima E, Reader JS. Natural aminoacyl tRNA synthetase fragment enhances cardiac function after myocardial infarction. PLoS One 2014; 9:e109325. [PMID: 25296172 PMCID: PMC4190278 DOI: 10.1371/journal.pone.0109325] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 09/10/2014] [Indexed: 12/03/2022] Open
Abstract
A naturally-occurring fragment of tyrosyl-tRNA synthetase (TyrRS) has been shown in higher eukaryotes to ‘moonlight’ as a pro-angiogenic cytokine in addition to its primary role in protein translation. Pro-angiogenic cytokines have previously been proposed to be promising therapeutic mechanisms for the treatment of myocardial infarction. Here, we show that systemic delivery of the natural fragment of TyRS, mini-TyrRS, improves heart function in mice after myocardial infarction. This improvement is associated with reduced formation of scar tissue, increased angiogenesis of cardiac capillaries, recruitment of c-kitpos cells and proliferation of myocardial fibroblasts. This work demonstrates that mini-TyrRS has beneficial effects on cardiac repair and regeneration and offers support for the notion that elucidation of the ever expanding repertoire of noncanonical functions of aminoacyl tRNA synthetases offers unique opportunities for development of novel therapeutics.
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Affiliation(s)
- Margaret E. McCormick
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Mauricio Rojas
- UNC McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Tyler Moser-Katz
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Ellie Tzima
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- UNC McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - John S. Reader
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
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7
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Breckenridge RA, Piotrowska I, Ng KE, Ragan TJ, West JA, Kotecha S, Towers N, Bennett M, Kienesberger PC, Smolenski RT, Siddall HK, Offer JL, Mocanu MM, Yelon DM, Dyck JRB, Griffin JL, Abramov AY, Gould AP, Mohun TJ. Hypoxic regulation of hand1 controls the fetal-neonatal switch in cardiac metabolism. PLoS Biol 2013; 11:e1001666. [PMID: 24086110 PMCID: PMC3782421 DOI: 10.1371/journal.pbio.1001666] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 08/15/2013] [Indexed: 12/15/2022] Open
Abstract
This study reveals a novel pathway that responds to hypoxia and modulates energy metabolism by cardiomyocytes in the mouse heart, thereby determining oxygen consumption. Cardiomyocytes are vulnerable to hypoxia in the adult, but adapted to hypoxia in utero. Current understanding of endogenous cardiac oxygen sensing pathways is limited. Myocardial oxygen consumption is determined by regulation of energy metabolism, which shifts from glycolysis to lipid oxidation soon after birth, and is reversed in failing adult hearts, accompanying re-expression of several “fetal” genes whose role in disease phenotypes remains unknown. Here we show that hypoxia-controlled expression of the transcription factor Hand1 determines oxygen consumption by inhibition of lipid metabolism in the fetal and adult cardiomyocyte, leading to downregulation of mitochondrial energy generation. Hand1 is under direct transcriptional control by HIF1α. Transgenic mice prolonging cardiac Hand1 expression die immediately following birth, failing to activate the neonatal lipid metabolising gene expression programme. Deletion of Hand1 in embryonic cardiomyocytes results in premature expression of these genes. Using metabolic flux analysis, we show that Hand1 expression controls cardiomyocyte oxygen consumption by direct transcriptional repression of lipid metabolising genes. This leads, in turn, to increased production of lactate from glucose, decreased lipid oxidation, reduced inner mitochondrial membrane potential, and mitochondrial ATP generation. We found that this pathway is active in adult cardiomyocytes. Up-regulation of Hand1 is protective in a mouse model of myocardial ischaemia. We propose that Hand1 is part of a novel regulatory pathway linking cardiac oxygen levels with oxygen consumption. Understanding hypoxia adaptation in the fetal heart may allow development of strategies to protect cardiomyocytes vulnerable to ischaemia, for example during cardiac ischaemia or surgery. Regulation of oxygen usage in cardiomyocytes is of great medical interest, because adult cardiac tissue is extremely vulnerable to hypoxia during myocardial infarction and cardiac surgery. While some progress has been made toward protecting cardiomyocytes from hypoxia in these circumstances, it has been limited by a lack of understanding of endogenous oxygen-sensing pathways. In contrast to adult cardiac tissue, embryonic cardiomyocytes are highly resistant to hypoxia, although the mechanisms underlying this have hitherto been unclear. Using mice we show that the transcription factor Hand1 is expressed at high levels in the fetal heart, under direct control of HIF1α signaling, a pathway well known to respond to hypoxia. We show that Hand1 expression decreases at birth as the neonate is exposed to higher levels of oxygen. By experimentally increasing Hand1 expression in the neonatal heart, we see lower oxygen consumption in cardiomyocytes and this is caused by Hand1 repressing key regulatory genes involved in cardiomyocyte lipid metabolism. This has the effect of decreasing mitochondrial ATP generation via the tricarboxylic acid cycle. Furthermore, we show that increasing Hand1 expression in adult transgenic hearts is protective against myocardial infarction, suggesting that a hypoxia–Hand1 pathway may also be of importance in the adult heart.
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Affiliation(s)
- Ross A. Breckenridge
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
- Division of Medicine, University College London, London, United Kingdom
- * E-mail:
| | - Izabela Piotrowska
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
| | - Keat-Eng Ng
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
| | - Timothy J. Ragan
- Division of Molecular Structure, MRC–National Institute for Medical Research, London, United Kingdom
| | - James A. West
- Department of Biochemistry, Cambridge University, Cambridge, United Kingdom
| | - Surendra Kotecha
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
| | - Norma Towers
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
| | - Michael Bennett
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
| | - Petra C. Kienesberger
- Cardiovascular Research Centre, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | | | - Hillary K. Siddall
- Hatter Institute, Institute of Cardiovascular Sciences, University College London, London, United Kingdom
| | - John L. Offer
- Physical Biochemistry, MRC–National Institute for Medical Research, London, United Kingdom
| | - Mihaela M. Mocanu
- Hatter Institute, Institute of Cardiovascular Sciences, University College London, London, United Kingdom
| | - Derek M. Yelon
- Hatter Institute, Institute of Cardiovascular Sciences, University College London, London, United Kingdom
| | - Jason R. B. Dyck
- Cardiovascular Research Centre, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jules L. Griffin
- Department of Biochemistry, Cambridge University, Cambridge, United Kingdom
| | - Andrey Y. Abramov
- Institute of Neurology, University College London, London, United Kingdom
| | - Alex P. Gould
- Division of Physiology and Metabolism, MRC–National Institute for Medical Research, London, United Kingdom
| | - Timothy J. Mohun
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
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8
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Krenz M, Baines C, Kalogeris T, Korthuis R. Cell Survival Programs and Ischemia/Reperfusion: Hormesis, Preconditioning, and Cardioprotection. ACTA ACUST UNITED AC 2013. [DOI: 10.4199/c00090ed1v01y201309isp044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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9
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Giordano C, Kuraitis D, Beanlands RSB, Suuronen EJ, Ruel M. Cell-based vasculogenic studies in preclinical models of chronic myocardial ischaemia and hibernation. Expert Opin Biol Ther 2012; 13:411-28. [PMID: 23256710 DOI: 10.1517/14712598.2013.748739] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
INTRODUCTION Coronary artery disease commonly leads to myocardial ischaemia and hibernation. Relevant preclinical models of these conditions are essential to evaluate new therapeutic options such as cell-based vasculogenic therapies. AREAS COVERED In this article, the authors first review basic concepts of myocardial ischaemia/hibernation and relevant techniques to assess myocardial viability. Then, preclinical models of chronic myocardial ischaemia and hibernation, induced by devices such as ameroid constrictors, Delrin stenosis, hydraulic occluders, and coils/stents are described. Lastly, the authors discuss cell-based vasculogenic therapy, and summarise studies conducted in large animal models of chronic myocardial ischaemia and hibernation. EXPERT OPINION Approximately one-third of patients with viable myocardium do not undergo revascularisation; however, this population is at high risk for cardiac events and would surely benefit from effective cell-based therapy. Because of the modest benefits in clinical studies, preclinical models accurately representing clinical myocardial ischemia/hibernation are necessary to better understand and appropriately direct regenerative therapy research.
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Affiliation(s)
- Céline Giordano
- University of Ottawa Heart Institute, Division of Cardiac Surgery, 40 Ruskin Street, Suite 3403, Ottawa, Ontario, K1Y 4W7, Canada
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10
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Frosini M, Larini A, Ricci L, Lucas L, Gorelli B, Sgaragli G, Tanganelli P, Valoti M. Effects of autologous, cross-linked erythrocytes on isolated hypoperfused rabbit heart dynamics. Pharmacology 2012; 90:274-80. [PMID: 23038665 DOI: 10.1159/000341910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 07/16/2012] [Indexed: 11/19/2022]
Abstract
The present study was aimed at assessing the effects of either red blood cells (RBC) or RBC cross-linked with the bifunctional dimethyl suberimidate reagent (C-RBC) on contractile force (CFo), heart rate (HR) and coronary flow (CF) of the isolated rabbit heart hypoperfused with RBC suspensions under 30 mm Hg constant pressure. RBC or C-RBC caused a rapid and marked reduction of CF, CFo and HR. In RBC-treated hearts, however, reperfusion with Tyrode solution partially restored the initial myocardial parameters, while in C-RBC-treated hearts a rapid impairment of diastolic relaxation with a subsequent, steady and increasing heart contracture was observed. Histological analysis showed that in C-RBC-perfused hearts either capillaries or precapillary arterioles were occluded by C-RBC in spite of extensive washings with Tyrode solution. These findings indicate that C-RBC impair coronary circulation markedly and irreversibly.
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Affiliation(s)
- Maria Frosini
- Dipartimento di Neuroscienze, Sezione di Farmacologia, Università degli Studi di Siena, Siena, Italy.
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Kalogeris T, Baines CP, Krenz M, Korthuis RJ. Cell biology of ischemia/reperfusion injury. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 298:229-317. [PMID: 22878108 PMCID: PMC3904795 DOI: 10.1016/b978-0-12-394309-5.00006-7] [Citation(s) in RCA: 1385] [Impact Index Per Article: 115.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Disorders characterized by ischemia/reperfusion (I/R), such as myocardial infarction, stroke, and peripheral vascular disease, continue to be among the most frequent causes of debilitating disease and death. Tissue injury and/or death occur as a result of the initial ischemic insult, which is determined primarily by the magnitude and duration of the interruption in the blood supply, and then subsequent damage induced by reperfusion. During prolonged ischemia, ATP levels and intracellular pH decrease as a result of anaerobic metabolism and lactate accumulation. As a consequence, ATPase-dependent ion transport mechanisms become dysfunctional, contributing to increased intracellular and mitochondrial calcium levels (calcium overload), cell swelling and rupture, and cell death by necrotic, necroptotic, apoptotic, and autophagic mechanisms. Although oxygen levels are restored upon reperfusion, a surge in the generation of reactive oxygen species occurs and proinflammatory neutrophils infiltrate ischemic tissues to exacerbate ischemic injury. The pathologic events induced by I/R orchestrate the opening of the mitochondrial permeability transition pore, which appears to represent a common end-effector of the pathologic events initiated by I/R. The aim of this treatise is to provide a comprehensive review of the mechanisms underlying the development of I/R injury, from which it should be apparent that a combination of molecular and cellular approaches targeting multiple pathologic processes to limit the extent of I/R injury must be adopted to enhance resistance to cell death and increase regenerative capacity in order to effect long-lasting repair of ischemic tissues.
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Affiliation(s)
- Theodore Kalogeris
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, USA
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12
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Handley MG, Medina RA, Nagel E, Blower PJ, Southworth R. PET imaging of cardiac hypoxia: opportunities and challenges. J Mol Cell Cardiol 2011; 51:640-50. [PMID: 21781973 DOI: 10.1016/j.yjmcc.2011.07.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 06/30/2011] [Accepted: 07/04/2011] [Indexed: 12/21/2022]
Abstract
Myocardial hypoxia is a major factor in the pathology of cardiac ischemia and myocardial infarction. Hypoxia also occurs in microvascular disease and cardiac hypertrophy, and is thought to be a prime determinant of the progression to heart failure, as well as the driving force for compensatory angiogenesis. The non-invasive delineation and quantification of hypoxia in cardiac tissue therefore has the potential to be an invaluable experimental, diagnostic and prognostic biomarker for applications in cardiology. However, at this time there are no validated methodologies sufficiently sensitive or reliable for clinical use. PET imaging provides real-time spatial information on the biodistribution of injected radiolabeled tracer molecules. Its inherent high sensitivity allows quantitative imaging of these tracers, even when injected at sub-pharmacological (≥pM) concentrations, allowing the non-invasive investigation of biological systems without perturbing them. PET is therefore an attractive approach for the delineation and quantification of cardiac hypoxia and ischemia. In this review we discuss the key concepts which must be considered when imaging hypoxia in the heart. We summarize the PET tracers which are currently available, and we look forward to the next generation of hypoxia-specific PET imaging agents currently being developed. We describe their potential advantages and shortcomings compared to existing imaging approaches, and what is needed in terms of validation and characterization before these agents can be exploited clinically.
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Affiliation(s)
- M G Handley
- Division of Imaging Sciences & Biomedical Engineering, King's College London, The Rayne Institute, 4th Floor Lambeth Wing, St. Thomas' Hospital, Lambeth Palace Rd., London, SE1 7EH, UK
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13
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Mayr M, May D, Gordon O, Madhu B, Gilon D, Yin X, Xing Q, Drozdov I, Ainali C, Tsoka S, Xu Q, Griffiths J, Horrevoets A, Keshet E. Metabolic homeostasis is maintained in myocardial hibernation by adaptive changes in the transcriptome and proteome. J Mol Cell Cardiol 2011; 50:982-90. [PMID: 21354174 PMCID: PMC3107937 DOI: 10.1016/j.yjmcc.2011.02.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 01/31/2011] [Accepted: 02/14/2011] [Indexed: 11/18/2022]
Abstract
A transgenic mouse model for conditional induction of long-term hibernation via myocardium-specific expression of a VEGF-sequestering soluble receptor allowed the dissection of the hibernation process into an initiation and a maintenance phase. The hypoxic initiation phase was characterized by peak levels of K(ATP) channel and glucose transporter 1 (GLUT1) expression. Glibenclamide, an inhibitor of K(ATP) channels, blocked GLUT1 induction. In the maintenance phase, tissue hypoxia and GLUT1 expression were reduced. Thus, we employed a combined "-omics" approach to resolve this cardioprotective adaptation process. Unguided bioinformatics analysis on the transcriptomic, proteomic and metabolomic datasets confirmed that anaerobic glycolysis was affected and that the observed enzymatic changes in cardiac metabolism were directly linked to hypoxia-inducible factor (HIF)-1 activation. Although metabolite concentrations were kept relatively constant, the combination of the proteomic and transcriptomic dataset improved the statistical confidence of the pathway analysis by 2 orders of magnitude. Importantly, proteomics revealed a reduced phosphorylation state of myosin light chain 2 and cardiac troponin I within the contractile apparatus of hibernating hearts in the absence of changes in protein abundance. Our study demonstrates how combining different "-omics" datasets aids in the identification of key biological pathways: chronic hypoxia resulted in a pronounced adaptive response at the transcript and the protein level to keep metabolite levels steady. This preservation of metabolic homeostasis is likely to contribute to the long-term survival of the hibernating myocardium.
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Affiliation(s)
- Manuel Mayr
- King's British Heart Foundation Centre, King's College London, London, UK.
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14
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Ghodsizad A, Ungerer MN, Bordel V, Kallenbach K, Kögler G, Bruckner B, Niehaus M, Gregoric I, Karck M, Ruhparwar A. Transplanted human cord blood-derived unrestricted somatic stem cells preserve high-energy reserves at the site of acute myocardial infarction. Cytotherapy 2011; 13:956-61. [PMID: 21417564 DOI: 10.3109/14653249.2011.563290] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND AIMS It has been demonstrated that transplantation of human cord blood-derived unrestricted somatic stem cells (USSC) in a porcine model of acute myocardial infarction (MI) significantly improved left ventricular (LV) function and prevented scar formation as well as LV dilation. Differentiation, apoptosis and macrophage mobilization at the infarct site could be excluded as the underlying mechanisms. The paracrine effect of the cells is most likely to be observed as the cause for the USSC treatment. The aim of our study was to examine the cardiomyocyte metabolism and the role of high-energy phosphates at the marginal infarct. Methods. USSC were transplanted into the myocardium of the LV, which was supplied by a ligated circumflex artery. Forty-eight hours later, the hearts were harvested and biopsies were performed from the marginal infarct zone surrounding the site of the cell injection. The concentrations of creatinine phosphate (CP), adenosine monophosphate (AMP), adenosine diphosphate (ADP) and adenosine triphosphate (ATP) were determined by chromatography. RESULTS The concentration of ADP, ATP and CP in the marginal zone of the infarction was significantly higher in the USSC group. The mean global left ventricular ejection fraction (LVEF) (SD) was 64% (8%) before MI; post-MI, LVEF decreased to 35% (9%). CONCLUSIONS Preservation of high-energy phosphates in the marginal infarct zone suggests that the preservation of energy reserves of surviving cardiomyocytes is a possible mechanism of action of transplanted stem cells in acutely ischemic myocardium.
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Affiliation(s)
- Ali Ghodsizad
- Debakey Heart and Vascular Center , The Methodist Hospital, Houston, Texas, USA
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15
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Turgut O, Tandogan I, Karapinar H, Aydin G. Preconditioning, postconditioning, stunning and hibernation: Towards an integrated insight into the mechanisms of hypoperfusion/reperfusion. Int J Cardiol 2011; 146:442-3. [DOI: 10.1016/j.ijcard.2010.10.112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2010] [Accepted: 10/23/2010] [Indexed: 11/15/2022]
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16
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Is detection of hibernating myocardium necessary in deciding revascularization in systolic heart failure? Am J Cardiol 2010; 106:236-42. [PMID: 20599009 DOI: 10.1016/j.amjcard.2010.02.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 02/21/2010] [Accepted: 02/21/2010] [Indexed: 01/12/2023]
Abstract
Although the prognosis of systolic heart failure, also called heart failure with reduced ejection fraction, has improved with advances in therapy, the prognosis remains poor in patients who become refractory to such therapies. That cardiac transplantation improves the quality of life and survival of such patients has been established, but it is available to a very small number of patients. Thus, newer pharmacologic and nonpharmacologic therapies for patients with refractory systolic heart failure are being explored. Because chronic ischemic heart disease is the most common cause of systolic heart failure, potential exists for revascularization therapy. Although revascularization can be performed with low procedural mortality, improvement in left ventricular function, relief of symptoms, and long-term prognosis appear to be related to the presence and extent of viable ischemic hibernating myocardium. In conclusion, the detection of hibernating myocardium is highly desirable before revascularization treatment is undertaken.
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17
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Abstract
In the myocardial cell, a series of enzyme-catalyzed reactions results in the efficient transfer of chemical energy into mechanical energy. The goals of this article are to emphasize the ability of noninvasive imaging techniques using isotopic tracers to detect the metabolic footprints of heart disease and to propose that cardiac metabolic imaging is more than a useful adjunct to current myocardial perfusion imaging studies. A strength of metabolic imaging is in the assessment of regional myocardial differences in metabolic activity, probing for 1 substrate at a time. We hope that new and developing methods of cardiac imaging will lead to the earlier detection of heart disease and improve the management and quality of life for patients afflicted with ischemic and nonischemic heart muscle disorders.
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Affiliation(s)
- Heinrich Taegtmeyer
- Division of Cardiology, Department of Internal Medicine, University of Texas Medical School at Houston, Houston, Texas 77030, USA.
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18
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Gene expression profiling of human hibernating myocardium: Increased expression of B-type natriuretic peptide and proenkephalin in hypocontractilevsnormally-contracting regions of the heart. Eur J Heart Fail 2008; 10:1177-80. [DOI: 10.1016/j.ejheart.2008.08.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 05/01/2008] [Accepted: 08/14/2008] [Indexed: 11/22/2022] Open
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Laflamme MA, Zbinden S, Epstein SE, Murry CE. Cell-based therapy for myocardial ischemia and infarction: pathophysiological mechanisms. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2008; 2:307-39. [PMID: 18039102 DOI: 10.1146/annurev.pathol.2.010506.092038] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cell-based cardiac repair has emerged as an attractive approach to preventing or reversing heart failure resulting from myocyte dysfunction-e.g., due to infarction-and to enhancing the development of collaterals in patients with symptoms of myocardial ischemia. These two problems involve both overlapping and differing mechanisms, and these differences must be considered in cell-based therapies. In terms of myocardial dysfunction due to infarction, only committed cardiomyocytes have been shown to form new myocardium that is electrically coupled with the host heart. Despite this, multiple cell populations appear to improve function of the infarcted heart, including many that are clearly nonmyogenic. In terms of myocardial ischemia, although cell-based strategies improve ischemia in animal models, clinical trials to date have not shown robustly beneficial results. We review the evidence for potential mechanisms underlying the benefits of cell transplantation in the heart and discuss the clinical contexts in which they may be relevant.
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Affiliation(s)
- Michael A Laflamme
- Department of Pathology, Center for Cardiovascular Biology, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington 98109, USA.
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20
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Qiu H, Dai H, Jain K, Shah R, Hong C, Pain J, Tian B, Vatner DE, Vatner SF, Depre C. Characterization of a novel cardiac isoform of the cell cycle-related kinase that is regulated during heart failure. J Biol Chem 2008; 283:22157-65. [PMID: 18508765 DOI: 10.1074/jbc.m710459200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myocardial infarction (MI) is often followed by heart failure (HF), but the mechanisms precipitating the transition to HF remain largely unknown. A genomic profile was performed in a monkey model of MI, from the myocardium adjacent to chronic (2-month) MI followed by 3 weeks of pacing to develop HF. The transcript of the gene encoding the cell cycle-related kinase (CCRK) was down-regulated by 50% in HF heart compared with control (p<0.05), which was confirmed by quantitative PCR. The CCRK sequence cloned from a heart library showed a conservation of the N-terminal kinase domain when compared with the "generic" isoform cloned previously but a different C-terminal half due to alternative splicing with frameshift. The homology of the cardiac sequence was 100% between mice and humans. Expression of the corresponding protein, measured upon generation of a monoclonal antibody, was limited to heart, liver, and kidney. Upon overexpression in cardiac myocytes, both isoforms promote cell growth and reduce apoptosis by chelerythrine (p<0.05 versus control). Using a yeast two-hybrid screening, we found an interaction of the generic but not the cardiac CCRK with cyclin H and casein kinase 2. In addition, only the generic CCRK phosphorylates the cyclin-dependent kinase 2, which was accompanied by a doubling of myocytes in the S and G(2) phases of the cell cycle (p < 0.05 versus control). Therefore, the heart expresses a splice variant of CCRK, which promotes cardiac cell growth and survival; differs from the generic isoform in terms of protein-protein interactions, substrate specificity and regulation of the cell cycle; and is down-regulated significantly in HF.
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Affiliation(s)
- Hongyu Qiu
- Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey 07103, USA
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21
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Saxena A, Fish JE, White MD, Yu S, Smyth JWP, Shaw RM, DiMaio JM, Srivastava D. Stromal cell-derived factor-1alpha is cardioprotective after myocardial infarction. Circulation 2008; 117:2224-31. [PMID: 18427137 DOI: 10.1161/circulationaha.107.694992] [Citation(s) in RCA: 195] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Heart disease is a leading cause of mortality throughout the world. Tissue damage from vascular occlusive events results in the replacement of contractile myocardium by nonfunctional scar tissue. The potential of new technologies to regenerate damaged myocardium is significant, although cell-based therapies must overcome several technical barriers. One possible cell-independent alternative is the direct administration of small proteins to damaged myocardium. METHODS AND RESULTS Here we show that the secreted signaling protein stromal cell-derived factor-1alpha (SDF-1alpha), which activates the cell-survival factor protein kinase B (PKB/Akt) via the G protein-coupled receptor CXCR4, protected tissue after an acute ischemic event in mice and activated Akt within endothelial cells and myocytes of the heart. Significantly better cardiac function than in control mice was evident as early as 24 hours after infarction as well as at 3, 14, and 28 days after infarction. Prolonged survival of hypoxic myocardium was followed by an increase in levels of vascular endothelial growth factor protein and neoangiogenesis. Consistent with improved cardiac function, mice exposed to SDF-1alpha demonstrated significantly decreased scar formation than control mice. CONCLUSIONS These findings suggest that SDF-1alpha may serve a tissue-protective and regenerative role for solid organs suffering a hypoxic insult.
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Affiliation(s)
- Ankur Saxena
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St, San Francisco, CA 94158, USA
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22
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Cardiomyocyte death and renewal in the normal and diseased heart. Cardiovasc Pathol 2008; 17:349-74. [PMID: 18402842 DOI: 10.1016/j.carpath.2008.02.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Revised: 11/30/2007] [Accepted: 02/04/2008] [Indexed: 02/07/2023] Open
Abstract
During post-natal maturation of the mammalian heart, proliferation of cardiomyocytes essentially ceases as cardiomyocytes withdraw from the cell cycle and develop blocks at the G0/G1 and G2/M transition phases of the cell cycle. As a result, the response of the myocardium to acute stress is limited to various forms of cardiomyocyte injury, which can be modified by preconditioning and reperfusion, whereas the response to chronic stress is dominated by cardiomyocyte hypertrophy and myocardial remodeling. Acute myocardial ischemia leads to injury and death of cardiomyocytes and nonmyocytic stromal cells by oncosis and apoptosis, and possibly by a hybrid form of cell death involving both pathways in the same ischemic cardiomyocytes. There is increasing evidence for a slow, ongoing turnover of cardiomyocytes in the normal heart involving death of cardiomyocytes and generation of new cardiomyocytes. This process appears to be accelerated and quantitatively increased as part of myocardial remodeling. Cardiomyocyte loss involves apoptosis, autophagy, and oncosis, which can occur simultaneously and involve different individual cardiomyocytes in the same heart undergoing remodeling. Mitotic figures in myocytic cells probably represent maturing progeny of stem cells in most cases. Mitosis of mature cardiomyocytes that have reentered the cell cycle appears to be a rare event. Thus, cardiomyocyte renewal likely is mediated primarily by endogenous cardiac stem cells and possibly by blood-born stem cells, but this biological phenomenon is limited in capacity. As a consequence, persistent stress leads to ongoing remodeling in which cardiomyocyte death exceeds cardiomyocyte renewal, resulting in progressive heart failure. Intense investigation currently is focused on cell-based therapies aimed at retarding cardiomyocyte death and promoting myocardial repair and possibly regeneration. Alteration of pathological remodeling holds promise for prevention and treatment of heart failure, which is currently a major cause of morbidity and mortality and a major public health problem. However, a deeper understanding of the fundamental biological processes is needed in order to make lasting advances in clinical therapeutics in the field.
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Transgenic system for conditional induction and rescue of chronic myocardial hibernation provides insights into genomic programs of hibernation. Proc Natl Acad Sci U S A 2007; 105:282-7. [PMID: 18162550 DOI: 10.1073/pnas.0707778105] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
A key energy-saving adaptation to chronic hypoxia that enables cardiomyocytes to withstand severe ischemic insults is hibernation, i.e., a reversible arrest of contractile function. Whereas hibernating cardiomyocytes represent the critical reserve of dysfunctional cells that can be potentially rescued, a lack of a suitable animal model has hampered insights on this medically important condition. We developed a transgenic mouse system for conditional induction of long-term hibernation and a system to rescue hibernating cardiomyocytes at will. Via myocardium-specific induction (and, in turn, deinduction) of a VEGF-sequestering soluble receptor, we show that VEGF is indispensable for adjusting the coronary vasculature to match increased oxygen consumption and exploit this finding to generate a hypoperfused heart. Importantly, ensuing ischemia is tunable to a level at which large cohorts of cardiomyocytes are driven to enter a hibernation mode, without cardiac cell death. Relieving the VEGF blockade even months later resulted in rapid revascularization and full recovery of contractile function. Furthermore, we show that left ventricular remodeling associated with hibernation is also fully reversible. The unique opportunity to uncouple hibernation from other ischemic heart phenotypes (e.g., infarction) was used to determine the genetic program of hibernation; uncovering hypoxia-inducible factor target genes associated with metabolic adjustments and induced expression of several cardioprotective genes. Autophagy, specifically self-digestion of mitochondria, was identified as a key prosurvival mechanism in hibernating cardiomyocytes. This system may lend itself for examining the potential utility of treatments to rescue dysfunctional cardiomyocytes and reverse maladaptive remodeling.
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24
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Chen J, Yuan L, Sun M, Zhang L, Zhang S. Screening of hibernation-related genes in the brain of Rhinolophus ferrumequinum during hibernation. Comp Biochem Physiol B Biochem Mol Biol 2007; 149:388-93. [PMID: 18055242 DOI: 10.1016/j.cbpb.2007.10.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2007] [Revised: 10/29/2007] [Accepted: 10/29/2007] [Indexed: 01/17/2023]
Abstract
The greater horseshoe bat (Rhinolophus ferrumequinum) is a widely distributed small mammal that hibernates annually. A systematic study was initiated to identify differentially expressed genes in hibernating and aroused states of the greater horseshoe bat brain by using suppressed subtractive hybridization technique and dot blot. Forty-one over-expressed ESTs in the hibernating state were found and 17 were known genes reported in NCBI. Among these 17 genes, three were further checked by real time PCR. The bioinformatics analysis suggests that the major over-expressed ESTs may be responsible for the regulation of cell cycle and apoptosis, the growth of neurons, signal transduction and neuroprotection, gene expression regulation, and intracellular trafficking.
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Affiliation(s)
- Jinping Chen
- South China Institute of Endangered Animals, Guangzhou, 510260, China
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25
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Rajabi M, Kassiotis C, Razeghi P, Taegtmeyer H. Return to the fetal gene program protects the stressed heart: a strong hypothesis. Heart Fail Rev 2007; 12:331-43. [PMID: 17516164 DOI: 10.1007/s10741-007-9034-1] [Citation(s) in RCA: 318] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A common feature of the hemodynamically or metabolically stressed heart is the return to a pattern of fetal metabolism. A hallmark of fetal metabolism is the predominance of carbohydrates as substrates for energy provision in a relatively hypoxic environment. When the normal heart is exposed to an oxygen rich environment after birth, energy substrate metabolism is rapidly switched to oxidation of fatty acids. This switch goes along with the expression of "adult" isoforms of metabolic enzymes and other proteins. However, the heart retains the ability to return to the "fetal" gene program. Specifically, the fetal gene program is predominant in a variety of pathophysiologic conditions including hypoxia, ischemia, hypertrophy, and atrophy. A common feature of all of these conditions is extensive remodeling, a decrease in the rate of aerobic metabolism in the cardiomyocyte, and an increase in cardiac efficiency. The adaptation is associated with a whole program of cell survival under stress. The adaptive mechanisms are prominently developed in hibernating myocardium, but they are also a feature of the failing heart muscle. We propose that in failing heart muscle at a certain point the fetal gene program is no longer sufficient to support cardiac structure and function. The exact mechanisms underlying the transition from adaptation to cardiomyocyte dysfunction are still not completely understood.
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Affiliation(s)
- Mitra Rajabi
- Department of Internal Medicine, Division of Cardiology, University of Texas-Houston Medical School, 6431 Fannin, Houston, TX 77030, USA
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Stroikin Y, Johansson U, Asplund S, Ollinger K. Increased resistance of lipofuscin-loaded prematurely senescent fibroblasts to starvation-induced programmed cell death. Biogerontology 2006; 8:43-53. [PMID: 16850182 DOI: 10.1007/s10522-006-9029-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Accepted: 05/27/2006] [Indexed: 11/29/2022]
Abstract
Alterations of cellular structures often found in ageing cells is mainly the result of production of reactive oxygen species and a consequence of aerobic life. Both oxidative stress and decreased degradative capacity of lysosomal system cause accumulation of intralysosomal age-related pigment called lipofuscin. To investigate the influence of lipofuscin on cell function, we compared survival of lipofuscin-loaded and control human fibroblasts following complete starvation induced by exposure to phosphate-buffered saline (PBS). Starving of control fibroblasts resulted in lysosomal alkalinisation, relocation of cathepsin D to the cytosol, caspase-3 activation and, finally, cell death, which became evident 72 h after the start of exposure to PBS. Increase of lysosomal pH was significantly less prominent in lipofuscin-loaded cells than in controls and was accompanied neither by leakage of cathepsin D nor by caspase-3 activation even 96 h after the initiation of starvation. Suppression of autophagy by 3-methyladenine (3-MA) accelerated cell death, while inhibition of cathepsin D delayed it, implying an important role of autophagy in cell survival during starvation and showing the involvement of lysosomes in starvation-induced cell death. Disturbed apoptotic response found in lipofuscin-loaded cells can be interpreted as an example of hormesis--an adaptation to low doses of otherwise harmful agents, in this case of lipofuscin, which has a protective effect at moderate amounts but becomes toxic at large quantities.
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Affiliation(s)
- Yuri Stroikin
- Faculty of Health Sciences, Division of Experimental Pathology, Department of Neuroscience and Locomotion, Linköping University, Sweden.
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27
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Carluccio E, Biagioli P, Alunni G, Murrone A, Giombolini C, Ragni T, Marino PN, Reboldi G, Ambrosio G. Patients With Hibernating Myocardium Show Altered Left Ventricular Volumes and Shape, Which Revert After Revascularization. J Am Coll Cardiol 2006; 47:969-77. [PMID: 16516079 DOI: 10.1016/j.jacc.2005.09.064] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2005] [Revised: 09/08/2005] [Accepted: 09/19/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVES The purpose of this study was to investigate whether post-ischemic left ventricular (LV) remodeling might be induced by regional contractile dysfunction per se (i.e., in the absence of transmural necrosis) and whether this phenomenon is potentially reversible after contractile recovery. BACKGROUND Formation of extensive scar tissue is thought to be chiefly responsible for post-infarction LV remodeling; however, myocardial necrosis also causes loss of contractility. We investigated LV geometry and shape in a setting in which contractile dysfunction occurs in the presence of preserved myocyte viability, and thus it is potentially reversible. METHODS In 42 patients with chronically dysfunctional myocardium, we evaluated (by two-dimensional echocardiography) LV global and regional function, volumes, and sphericity index (SI), at baseline and 8 +/- 3 months after coronary revascularization. Myocardial viability before revascularization was evaluated by dobutamine echocardiography. RESULTS At baseline, regional and global function were depressed and LV dilation was present. Revascularization was followed by recovery of ejection fraction (from 33 +/- 6% to 45 +/- 10%, p < 0.0001) and wall motion score index (from 2.29 +/- 0.31 to 1.74 +/- 0.42, p < 0.0001). After revascularization, significant improvement of end-systolic volume index (from 78 +/- 23 ml/m2 to 56 +/- 23 ml/m2, p < 0.0001), end-diastolic volume index (from 118 +/- 26 ml/m2 to 99 +/- 26 ml/m2, p < 0.0001), and SI (from 0.69 +/- 0.14 to 0.52 +/- 0.11, p < 0.0001) was also observed. Improvement in LV volumes and SI were significantly correlated to the number of segments recovering function after revascularization. CONCLUSIONS Hibernating myocardium is associated with major alterations in LV volumes and shape, which significantly revert after revascularization. Thus, chronic dyssynergy per se is sufficient to induce ischemic LV remodeling in patients.
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Affiliation(s)
- Erberto Carluccio
- Department of Cardiology, University of Perugia School of Medicine, Perugia, Italy
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