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Bhatt A, Bates MJ, Marcu CB, Matheny RG, Carabello BA, Yin K, Boyd WD. Second-generation extracellular matrix patch for epicardial infarct repair. J Cardiothorac Surg 2023; 18:255. [PMID: 37658440 PMCID: PMC10474747 DOI: 10.1186/s13019-023-02358-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 08/27/2023] [Indexed: 09/03/2023] Open
Abstract
Current myocardial infarction treatments focus on improving hemodynamics rather than addressing the problem of lost myocardium impairing left ventricular function. Epicardial infarct repair with a bioactive patch placed on the ischemic area is an emerging approach to promote endogenous myocardial repair. We report the use of a second-generation CorMatrix-extracellular matrix (ECM) patch as an adjunct to surgical revascularization in treating a young patient with diffuse, multivessel coronary artery disease unamenable to PCI and a large anterior myocardial infarction. The progressive myocardial scar shrinkage and increase in left ventricular ejection fraction from 10 to 51% are generally not observed with surgical revascularization therapy alone, suggesting this new patch has adjunctive potential to current revascularization therapy.
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Affiliation(s)
- Arjun Bhatt
- Department of Cardiovascular Sciences, Brody School of Medicine, East Carolina University, 115 Heart Drive, Greenville, NC, 27834, USA
| | - Michael J Bates
- Department of Cardiovascular Sciences, Brody School of Medicine, East Carolina University, 115 Heart Drive, Greenville, NC, 27834, USA
| | - Constantin B Marcu
- Department of Cardiovascular Sciences, Brody School of Medicine, East Carolina University, 115 Heart Drive, Greenville, NC, 27834, USA
| | | | - Blase A Carabello
- Department of Cardiovascular Sciences, Brody School of Medicine, East Carolina University, 115 Heart Drive, Greenville, NC, 27834, USA
| | - Kanhua Yin
- Department of Cardiovascular Sciences, Brody School of Medicine, East Carolina University, 115 Heart Drive, Greenville, NC, 27834, USA.
| | - Walter Douglas Boyd
- Department of Cardiovascular Sciences, Brody School of Medicine, East Carolina University, 115 Heart Drive, Greenville, NC, 27834, USA
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2
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Soni SS, D'Elia AM, Rodell CB. Control of the post-infarct immune microenvironment through biotherapeutic and biomaterial-based approaches. Drug Deliv Transl Res 2023; 13:1983-2014. [PMID: 36763330 PMCID: PMC9913034 DOI: 10.1007/s13346-023-01290-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2023] [Indexed: 02/11/2023]
Abstract
Ischemic heart failure (IHF) is a leading cause of morbidity and mortality worldwide, for which heart transplantation remains the only definitive treatment. IHF manifests from myocardial infarction (MI) that initiates tissue remodeling processes, mediated by mechanical changes in the tissue (loss of contractility, softening of the myocardium) that are interdependent with cellular mechanisms (cardiomyocyte death, inflammatory response). The early remodeling phase is characterized by robust inflammation that is necessary for tissue debridement and the initiation of repair processes. While later transition toward an immunoregenerative function is desirable, functional reorientation from an inflammatory to reparatory environment is often lacking, trapping the heart in a chronically inflamed state that perpetuates cardiomyocyte death, ventricular dilatation, excess fibrosis, and progressive IHF. Therapies can redirect the immune microenvironment, including biotherapeutic and biomaterial-based approaches. In this review, we outline these existing approaches, with a particular focus on the immunomodulatory effects of therapeutics (small molecule drugs, biomolecules, and cell or cell-derived products). Cardioprotective strategies, often focusing on immunosuppression, have shown promise in pre-clinical and clinical trials. However, immunoregenerative therapies are emerging that often benefit from exacerbating early inflammation. Biomaterials can be used to enhance these therapies as a result of their intrinsic immunomodulatory properties, parallel mechanisms of action (e.g., mechanical restraint), or by enabling cell or tissue-targeted delivery. We further discuss translatability and the continued progress of technologies and procedures that contribute to the bench-to-bedside development of these critically needed treatments.
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Affiliation(s)
- Shreya S Soni
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, 19104, USA
| | - Arielle M D'Elia
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, 19104, USA
| | - Christopher B Rodell
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, 19104, USA.
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3
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Ghanta RK, Pugazenthi A, Zhao Y, Sylvester C, Wall MJ, Mazur RA, Russell LN, Lampe KJ. Influence of Supraphysiologic Biomaterial Stiffness on Ventricular Mechanics and Myocardial Infarct Reinforcement. Acta Biomater 2022; 149:30-39. [PMID: 35820592 DOI: 10.1016/j.actbio.2022.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 07/02/2022] [Accepted: 07/05/2022] [Indexed: 11/15/2022]
Abstract
Injectable intramyocardial biomaterials have promise to limit adverse ventricular remodeling through mechanical and biologic mechanisms. While some success has been observed by injecting materials to regenerate new tissue, optimal biomaterial stiffness to thicken and stiffen infarcted myocardium to limit adverse remodeling has not been determined. In this work, we present an in-vivo study of the impact of biomaterial stiffness over a wide range of stiffness moduli on ventricular mechanics. We utilized injectable methacrylated polyethylene glycol (PEG) hydrogels fabricated at 3 different mechanical moduli: 5 kPa (low), 25 kPa (medium/myocardium), and 250 kPa (high/supraphysiologic). We demonstrate that the supraphysiological high stiffness favorably alters post-infarct ventricular mechanics and prevents negative tissue remodeling. Lower stiffness materials do not alter mechanics and thus to be effective, must instead target biological reparative mechanisms. These results may influence rationale design criteria for biomaterials developed for infarct reinforcement therapy. STATEMENT OF SIGNIFICANCE: Acellular biomaterials for cardiac application can provide benefit via mechanical and biological mechanisms post myocardial infarction. We study the role of biomaterial mechanical characteristics on ventricular mechanics in myocardial infarcts. Previous studies have not measured the influence of injected biomaterials on ventricular mechanics, and consequently rational design criteria is unknown. By utilizing an in-vivo assessment of ventricular mechanics, we demonstrate that low stiffness biomaterial do not alter pathologic ventricular mechanics. Thus, to be effective, low stiffness biomaterials must target biological reparative mechanisms. Physiologic and supra-physiologic biomaterials favorably alter post-infarct mechanics and prevents adverse ventricular remodeling.
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Affiliation(s)
- Ravi K Ghanta
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX United States; Department of Cardiovascular Surgery, Texas Heart Institute, Houston, TX United States.
| | - Aarthi Pugazenthi
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX United States
| | - Yunge Zhao
- Department of Surgery, University of Maryland, Baltimore, MD United States
| | - Christopher Sylvester
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX United States; Medical Scientist Training Program, Baylor College of Medicine, Houston, TX United States
| | - Mathew J Wall
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX United States
| | - Rachel A Mazur
- Department of Chemical Engineering, University of Virginia, Charlottesville, VA United States
| | - Lauren N Russell
- Department of Chemical Engineering, University of Virginia, Charlottesville, VA United States
| | - Kyle J Lampe
- Department of Chemical Engineering, University of Virginia, Charlottesville, VA United States
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4
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Shazly T, Smith A, Uline MJ, Spinale FG. Therapeutic payload delivery to the myocardium: Evolving strategies and obstacles. JTCVS OPEN 2022; 10:185-194. [PMID: 36004211 PMCID: PMC9390211 DOI: 10.1016/j.xjon.2022.04.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 04/19/2022] [Accepted: 04/27/2022] [Indexed: 06/15/2023]
Key Words
- BMC, bone marrow cell
- HF, heart failure
- ID, intracoronary delivery
- IMD, intramyocardial delivery
- IPD, intrapericardial delivery
- LV, left ventricle
- MI, myocardial infarct
- MSC, mesenchymal stem cell
- TED, transendocardial delivery
- bFGF, basic fibroblast growth factor
- biomaterial
- cardiac
- injection
- local delivery
- myocardium
- payload
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Affiliation(s)
- Tarek Shazly
- College of Engineering and Computing, School of Medicine, University of South Carolina, Columbia, SC
| | - Arianna Smith
- College of Arts and Sciences, Florida Gulf Coast University, Fort Myers, Fla
| | - Mark J. Uline
- College of Engineering and Computing, School of Medicine, University of South Carolina, Columbia, SC
| | - Francis G. Spinale
- College of Engineering and Computing, School of Medicine, University of South Carolina, Columbia, SC
- Cardiovascular Translational Research Center, School of Medicine, University of South Carolina, Columbia, SC
- Columbia VA Health Care System, Columbia, SC
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5
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Liu H, Soares JS, Walmsley J, Li DS, Raut S, Avazmohammadi R, Iaizzo P, Palmer M, Gorman JH, Gorman RC, Sacks MS. The impact of myocardial compressibility on organ-level simulations of the normal and infarcted heart. Sci Rep 2021; 11:13466. [PMID: 34188138 PMCID: PMC8242073 DOI: 10.1038/s41598-021-92810-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 05/25/2021] [Indexed: 11/09/2022] Open
Abstract
Myocardial infarction (MI) rapidly impairs cardiac contractile function and instigates maladaptive remodeling leading to heart failure. Patient-specific models are a maturing technology for developing and determining therapeutic modalities for MI that require accurate descriptions of myocardial mechanics. While substantial tissue volume reductions of 15-20% during systole have been reported, myocardium is commonly modeled as incompressible. We developed a myocardial model to simulate experimentally-observed systolic volume reductions in an ovine model of MI. Sheep-specific simulations of the cardiac cycle were performed using both incompressible and compressible tissue material models, and with synchronous or measurement-guided contraction. The compressible tissue model with measurement-guided contraction gave best agreement with experimentally measured reductions in tissue volume at peak systole, ventricular kinematics, and wall thickness changes. The incompressible model predicted myofiber peak contractile stresses approximately double the compressible model (182.8 kPa, 107.4 kPa respectively). Compensatory changes in remaining normal myocardium with MI present required less increase of contractile stress in the compressible model than the incompressible model (32.1%, 53.5%, respectively). The compressible model therefore provided more accurate representation of ventricular kinematics and potentially more realistic computed active contraction levels in the simulated infarcted heart. Our findings suggest that myocardial compressibility should be incorporated into future cardiac models for improved accuracy.
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Affiliation(s)
- Hao Liu
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The University of Texas at Austin, Austin, TX, USA
| | - João S Soares
- Engineered Tissue Multiscale Mechanics and Modeling Laboratory, Virginia Commonwealth University, Richmond, VA, USA
| | - John Walmsley
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The University of Texas at Austin, Austin, TX, USA
| | - David S Li
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The University of Texas at Austin, Austin, TX, USA
| | - Samarth Raut
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The University of Texas at Austin, Austin, TX, USA
| | - Reza Avazmohammadi
- Computational Cardiovascular Bioengineering Lab, Texas A&M University, College Station, TX, USA
| | - Paul Iaizzo
- Visible Heart Lab, University of Minnesota Twin Cities, Minneapolis, MN, USA
| | - Mark Palmer
- Corporate Core Technologies, Medtronic, Inc., Minneapolis, USA
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael S Sacks
- James T. Willerson Center for Cardiovascular Modeling and Simulation, The University of Texas at Austin, Austin, TX, USA.
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7
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Li W. Biomechanics of infarcted left Ventricle-A review of experiments. J Mech Behav Biomed Mater 2020; 103:103591. [PMID: 32090920 DOI: 10.1016/j.jmbbm.2019.103591] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 01/14/2023]
Abstract
Myocardial infarction (MI) is one of leading diseases to contribute to annual death rate of 5% in the world. In the past decades, significant work has been devoted to this subject. Biomechanics of infarcted left ventricle (LV) is associated with MI diagnosis, understanding of remodelling, MI micro-structure and biomechanical property characterizations as well as MI therapy design and optimization, but the subject has not been reviewed presently. In the article, biomechanics of infarcted LV was reviewed in terms of experiments achieved in the subject so far. The concerned content includes experimental remodelling, kinematics and kinetics of infarcted LVs. A few important issues were discussed and several essential topics that need to be investigated further were summarized. Microstructure of MI tissue should be observed even carefully and compared between different methods for producing MI scar in the same animal model, and eventually correlated to passive biomechanical property by establishing innovative constitutive laws. More uniaxial or biaxial tensile tests are desirable on MI, border and remote tissues, and viscoelastic property identification should be performed in various time scales. Active contraction experiments on LV wall with MI should be conducted to clarify impaired LV pumping function and supply necessary data to the function modelling. Pressure-volume curves of LV with MI during diastole and systole for the human are also desirable to propose and validate constitutive laws for LV walls with MI.
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Affiliation(s)
- Wenguang Li
- School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK.
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8
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Estrada AC, Yoshida K, Clarke SA, Holmes JW. Longitudinal Reinforcement of Acute Myocardial Infarcts Improves Function by Transmurally Redistributing Stretch and Stress. J Biomech Eng 2020; 142:021009. [PMID: 31201738 PMCID: PMC7104755 DOI: 10.1115/1.4044030] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 06/04/2019] [Indexed: 01/20/2023]
Abstract
A wide range of emerging therapies, from surgical restraint to biomaterial injection to tissue engineering, aim to improve heart function and limit adverse remodeling following myocardial infarction (MI). We previously showed that longitudinal surgical reinforcement of large anterior infarcts in dogs could significantly enhance systolic function without restricting diastolic function, but the underlying mechanisms for this improvement are poorly understood. The goal of this study was to construct a finite element model that could match our previously published data on changes in regional strains and left ventricular function following longitudinal surgical reinforcement, then use the model to explore potential mechanisms for the improvement in systolic function we observed. The model presented here, implemented in febio, matches all the key features of our experiments, including diastolic remodeling strains in the ischemic region, small shifts in the end-diastolic pressure-volume relationship (EDPVR), and large changes in the end-systolic pressure-volume relationship (ESPVR) in response to ischemia and to patch application. Detailed examination of model strains and stresses suggests that longitudinal reinforcement reduces peak diastolic fiber stretch and systolic fiber stress in the remote myocardium and shifts those peaks away from the endocardial surface by reshaping the left ventricle (LV). These findings could help to guide the development of novel therapies to improve post-MI function by providing specific design objectives.
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Affiliation(s)
- Ana Cristina Estrada
- Department of Biomedical Engineering, University of
Virginia, P.O. Box 800759, Health System,
Charlottesville, VA 22908
| | - Kyoko Yoshida
- Department of Biomedical Engineering, University of
Virginia, P.O. Box 800759, Health System,
Charlottesville, VA 22908
| | - Samantha A. Clarke
- Department of Biomedical Engineering, University of
Virginia, P.O. Box 800759, Health System,
Charlottesville, VA 22908
| | - Jeffrey W. Holmes
- Department of Biomedical Engineering, University of
Virginia, P.O. Box 800759, Health System,
Charlottesville, VA 22908; Department of Medicine, School of
Medicine, University of Virginia, P.O. Box
800759, Health System, Charlottesville, VA 22908; Robert M. Berne
Cardiovascular Research Center, University of Virginia,
P.O. Box 800759, Health System, Charlottesville, VA
22908; The Center for Engineering in Medicine, University
of Virginia, P.O. Box 800759, Health System,
Charlottesville, VA 22908
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9
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Rodell CB, Zhang ZL, Dusaj NN, Oquendo Y, Lee ME, Bouma W, Gorman JH, Burdick JA, Gorman RC. Injectable Shear-Thinning Hydrogels Prevent Ischemic Mitral Regurgitation and Normalize Ventricular Flow Dynamics. Semin Thorac Cardiovasc Surg 2019; 32:445-453. [PMID: 31682905 PMCID: PMC7195238 DOI: 10.1053/j.semtcvs.2019.10.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 10/23/2019] [Indexed: 11/11/2022]
Abstract
Injectable hydrogels are known to attenuate left-ventricular (LV) remodeling following myocardial infarction (MI), dependent on material mechanical properties. The effect of hydrogel injection on ischemic mitral regurgitation (IMR) resultant from LV remodeling remains relatively unexplored. This study uses multiple imaging methods to evaluate the efficacy of injectable hydrogels with tunable modulus to prevent post-MI development of IMR. Posterolateral MI was induced in 20 sheep with subsequent epicardial injection of saline (control (MI); n = 7), soft hydrogel (guest-host crosslinking, modulus <1 kPa, n = 7), or stiff hydrogel (dual-crosslinking, modulus = 41.4 ± 4.3 kPa, n = 6) within the infarct region and 8-week follow-up. IMR and valve geometry were assessed by echocardiography. LV geometry (long-axis dimension, posterior chordae length) and ventricular flow dynamics were assessed by magnetic resonance imaging. IMR developed in MI controls at 8 weeks and was attenuated with hydrogel treatment (IMR grade for MI: 1.86 ± 0.69; guest-host crosslinking: 1.29 ± 1.11; dual-crosslinking: 0.50 ± 0.55, P = 0.02 vs MI). Tethering of the posterior leaflet increased in MI controls, but not with stiff hydrogel treatment. Across cohorts, IMR was correlated with changes in the long-axis dimension (Spearman R = 0.77) and posterior chordae length (Spearman R = 0.64). Intraventricular flow dynamics were highly disturbed in MI controls, but stiff hydrogel treatment normalized flow patterns and reduced the prevalence of large (≥2+ MR, >5 mL) regurgitant volumes. Injectable hydrogels attenuated subvalvular remodeling and leaflet tethering, preventing IMR development and normalizing LV flow dynamics. Hydrogels with a supraphysiological modulus yielded best outcomes.
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Affiliation(s)
- Christopher B. Rodell
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
- Current affiliation: School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104
| | - Zhang L. Zhang
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Neville N. Dusaj
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Yousi Oquendo
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Madonna E. Lee
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Wobbe Bouma
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Joseph H. Gorman
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Jason A. Burdick
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Robert C. Gorman
- Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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10
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Efficacy of intramyocardial injection of Algisyl-LVR for the treatment of ischemic heart failure in swine. Int J Cardiol 2018; 255:129-135. [PMID: 29425550 DOI: 10.1016/j.ijcard.2017.09.179] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 08/15/2017] [Accepted: 09/20/2017] [Indexed: 12/23/2022]
Abstract
BACKGROUND Progressive thinning and dilation of the LV due to ischemic heart failure (IHF) increases wall stress and myocardial oxygen consumption. Injectable biopolymers implanted in the myocardial wall have been used to increase wall thickness to reduce chamber volume, decrease wall stress, and improve cardiac function. We sought to evaluate the efficacy of a biopolymer (Algisyl-LVR) to prevent left ventricular (LV) remodeling in a swine model of IHF. METHODS IHF was induced in 11 swine by occluding the marginal obtuse branches of the left circumflex artery. Eight weeks later, Algisyl-LVR was injected into the LV myocardial free wall in five of the 11 animals. Echocardiographic examinations were done every 2weeks for 16weeks. RESULTS Within eight weeks of treatment, the ejection fraction increased from 30.5%±7.7% to 42.4%±3.5% (treated group) vs. 37.3%±3.8% to 34.3%±2.9% (control), p<0.01. Stroke volume increased from 18.5±9.3mL to 41.3±13.3mL (treated group) vs. 25.4±2.3mL to 31.4±5.3mL (control), p<0.05. Wall thickness in end-diastole of the infarcted region changed from 0.69±0.06cm to 0.81±0.13cm (treated group) vs. 0.73±0.09cm to 0.68±0.11cm (control), p<0.05. Sphericity index remained almost unchanged after treatment, although differences were found at the end of the study between both groups (p<0.001). Average myofiber stress changed from 16.3±5.8kPa to 10.2±4.0kPa (treated group) vs. 15.2±4.8kPa to 17.9±5.6kPa (control), p<0.05. CONCLUSIONS Algisyl-LVR is an effective strategy that serves as a micro-LV assist device to reduce stress and hence prevent or reverse maladaptive cardiac remodeling caused by IHF in swine.
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11
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Caggiano LR, Lee JJ, Holmes JW. Surgical reinforcement alters collagen alignment and turnover in healing myocardial infarcts. Am J Physiol Heart Circ Physiol 2018; 315:H1041-H1050. [PMID: 30028201 DOI: 10.1152/ajpheart.00088.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies have suggested that the composition and global mechanical properties of the scar tissue that forms after a myocardial infarction (MI) are key determinants of long-term survival, and emerging therapies such as biomaterial injection are designed in part to alter those mechanical properties. However, recent evidence suggests that local mechanics regulate scar formation post-MI, so that perturbing infarct mechanics could have unexpected consequences. We therefore tested the effect of changes in local mechanical environment on scar collagen turnover, accumulation, and alignment in 77 Sprague-Dawley rats at 1, 2, 3 and 6 wk post-MI by sewing a Dacron patch to the epicardium to eliminate circumferential strain while permitting continued longitudinal stretching with each heart beat. We found that collagen in healing infarcts aligned parallel to regional strain and perpendicular to the preinfarction muscle and collagen fiber direction, strongly supporting our hypothesis that mechanical environment is the primary determinant of scar collagen alignment. Mechanical reinforcement reduced levels of carboxy-terminal propeptide of type I procollagen (PICP; a biomarker for collagen synthesis) in samples collected by microdialysis significantly, particularly in the first 2 wk. Reinforcement also reduced carboxy-terminal telopeptide of type I collagen (ICTP; a biomarker for collagen degradation), particularly at later time points. These alterations in collagen turnover produced no change in collagen area fraction as measured by histology but significantly reduced wall thickness in the reinforced scars compared with untreated controls. Our findings confirm the importance of regional mechanics in regulating scar formation after infarction and highlight the potential for therapies that reduce stretch to also reduce wall thickness in healing infarcts. NEW & NOTEWORTHY This study shows that therapies such as surgical reinforcement, which reduce stretch in healing infarcts, can also reduce collagen synthesis and wall thickness and modify collagen alignment in postinfarction scars.
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Affiliation(s)
- Laura R Caggiano
- Department of Biomedical Engineering, University of Virginia , Charlottesville, Virginia
| | - Jia-Jye Lee
- Department of Biomedical Engineering, University of Virginia , Charlottesville, Virginia
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, University of Virginia , Charlottesville, Virginia.,Department of Medicine, University of Virginia , Charlottesville, Virginia
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12
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Rodell CB, Lee ME, Wang H, Takebayashi S, Takayama T, Kawamura T, Arkles JS, Dusaj NN, Dorsey SM, Witschey WRT, Pilla JJ, Gorman JH, Wenk JF, Burdick JA, Gorman RC. Injectable Shear-Thinning Hydrogels for Minimally Invasive Delivery to Infarcted Myocardium to Limit Left Ventricular Remodeling. Circ Cardiovasc Interv 2017; 9:CIRCINTERVENTIONS.116.004058. [PMID: 27729419 DOI: 10.1161/circinterventions.116.004058] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 09/07/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND Injectable, acellular biomaterials hold promise to limit left ventricular remodeling and heart failure precipitated by infarction through bulking or stiffening the infarct region. A material with tunable properties (eg, mechanics, degradation) that can be delivered percutaneously has not yet been demonstrated. Catheter-deliverable soft hydrogels with in vivo stiffening to enhance therapeutic efficacy achieve these requirements. METHODS AND RESULTS We developed a hyaluronic acid hydrogel that uses a tandem crosslinking approach, where the first crosslinking (guest-host) enabled injection and localized retention of a soft (<1 kPa) hydrogel. A second crosslinking reaction (dual-crosslinking) stiffened the hydrogel (41.4±4.3 kPa) after injection. Posterolateral infarcts were investigated in an ovine model (n≥6 per group), with injection of saline (myocardial infarction control), guest-host hydrogels, or dual-crosslinking hydrogels. Computational (day 1), histological (1 day, 8 weeks), morphological, and functional (0, 2, and 8 weeks) outcomes were evaluated. Finite-element modeling projected myofiber stress reduction (>50%; P<0.001) with dual-crosslinking but not guest-host injection. Remodeling, assessed by infarct thickness and left ventricular volume, was mitigated by hydrogel treatment. Ejection fraction was improved, relative to myocardial infarction at 8 weeks, with dual-crosslinking (37% improvement; P=0.014) and guest-host (15% improvement; P=0.058) treatments. Percutaneous delivery via endocardial injection was investigated with fluoroscopic and echocardiographic guidance, with delivery visualized by magnetic resonance imaging. CONCLUSIONS A percutaneous delivered hydrogel system was developed, and hydrogels with increased stiffness were found to be most effective in ameliorating left ventricular remodeling and preserving function. Ultimately, engineered systems such as these have the potential to provide effective clinical options to limit remodeling in patients after infarction.
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Affiliation(s)
- Christopher B Rodell
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Madonna E Lee
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Hua Wang
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Satoshi Takebayashi
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Tetsushi Takayama
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Tomonori Kawamura
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Jeffrey S Arkles
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Neville N Dusaj
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Shauna M Dorsey
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Walter R T Witschey
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - James J Pilla
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Joseph H Gorman
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Jonathan F Wenk
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington
| | - Jason A Burdick
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington.
| | - Robert C Gorman
- From the Department of Bioengineering (C.B.R., N.N.D., S.M.D., J.A.B.), Gorman Cardiovascular Research Group, Department of Surgery (M.E.L., S.T., T.T., T.K., J.S.A., J.H.G., R.C.G.), and Department of Radiology (W.R.T.W., J.J.P.), University of Pennsylvania, Philadelphia; and Department of Mechanical Engineering (H.W., J.F.W.) and Department of Surgery (J.F.W.), University of Kentucky, Lexington.
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13
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Soares JS, Li DS, Lai E, Gorman JH, Gorman RC, Sacks MS. Modeling of Myocardium Compressibility and its Impact in Computational Simulations of the Healthy and Infarcted Heart. FUNCTIONAL IMAGING AND MODELING OF THE HEART : ... INTERNATIONAL WORKSHOP, FIMH ..., PROCEEDINGS. FIMH 2017; 10263:493-501. [PMID: 31080965 PMCID: PMC6510496 DOI: 10.1007/978-3-319-59448-4_47] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Simulation of heart function requires many components, including accurate descriptions of regional mechanical behavior of the normal and infarcted myocardium. Myocardial compressibility has been known for at least two decades, however its experimental measurement and incorporation into compu-tational simulations has not yet been widely utilized in contemporary cardiac models. In the present work, based on novel in-vivo ovine experimental data, we developed a specialized compressible model that reproduces the peculiar unim-odal compressible behavior of myocardium. Such simulations will be extremely valuable to understand etiology and pathophysiology of myocardium remodeling and its impact on tissue-level properties and organ-level cardiac function.
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Affiliation(s)
- Joao S Soares
- Center for Computational Simulation, Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, USA
| | - David S Li
- Center for Computational Simulation, Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, USA
| | - Eric Lai
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Michael S Sacks
- Center for Computational Simulation, Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, USA
- Gorman Cardiovascular Research Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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14
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The role of GILZ in modulation of adaptive immunity in a murine model of myocardial infarction. Exp Mol Pathol 2017; 102:408-414. [DOI: 10.1016/j.yexmp.2017.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 05/08/2017] [Indexed: 11/22/2022]
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15
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Huang CH, Kuo CL, Huang CS, Tseng WM, Lian IB, Chang CC, Liu CS. High plasma coenzyme Q10 concentration is correlated with good left ventricular performance after primary angioplasty in patients with acute myocardial infarction. Medicine (Baltimore) 2016; 95:e4501. [PMID: 27495100 PMCID: PMC4979854 DOI: 10.1097/md.0000000000004501] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 06/20/2016] [Accepted: 07/13/2016] [Indexed: 01/11/2023] Open
Abstract
Exogenous administration of coenzyme Q10 (CoQ10) has been shown in experimental models to have a protective effect against ischemia-reperfusion injury. However, it is unclear whether follow-up plasma CoQ10 concentration is prognostic of left ventricular (LV) performance after primary balloon angioplasty in patients with acute ST segment elevation myocardial infarction (STEMI).We prospectively recruited 55 patients with STEMI who were treated with primary coronary balloon angioplasty. Plasma CoQ10 concentrations were measured before primary angioplasty (baseline) and 3 days, 7 days, and 1 month after STEMI using high-performance liquid chromatography. Echocardiography was performed at baseline and at 6-month follow-up. The control group comprised 54 healthy age- and sex-matched volunteers.Serial circulating CoQ10 concentrations significantly decreased with time in the STEMI group. The LV ejection fraction at 6-month follow-up positively correlated with the 1-month plasma CoQ10 tertile. Higher plasma CoQ10 concentrations at 1 month were associated with favorable LV remodeling and systolic function 6 months after STEMI. Multiple linear regression analysis showed that changes in CoQ10 concentrations at 1-month follow-up were predictive of LV systolic function 6 months after STEMI. Changes in CoQ10 concentrations correlated negatively with baseline oxidized low-density lipoprotein and fibrinogen concentrations and correlated positively with leukocyte mitochondrial copy number at baseline.Patients with STEMI who had higher plasma CoQ10 concentrations 1 month after primary angioplasty had better LV performance at 6-month follow-up. In addition, higher plasma CoQ10 concentration was associated with lower grade inflammatory and oxidative stress status. Therefore, plasma CoQ10 concentration may serve as a novel prognostic biomarker of LV systolic function after revascularization therapy for acute myocardial infarction.
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Affiliation(s)
- Ching-Hui Huang
- Division of Cardiology, Department of Internal Medicine, Changhua Christian Hospital
- Institute of Statistics and Information Science, National Changhua University of Education
| | | | | | | | - Ie Bin Lian
- Institute of Statistics and Information Science, National Changhua University of Education
| | - Chia-Chu Chang
- Division of Nephrology, Department of Internal Medicine, Changhua Christian Hospital, Changhua
- School of Medicine, Chung Shan Medical University, Taichung
| | - Chin-San Liu
- Vascular and Genomic Research Center
- Department of Neurology, Changhua Christian Hospital, Changhua
- Graduate Institute of Integrative Medicine, China Medical University, Taichung, Taiwan
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16
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Clarke SA, Richardson WJ, Holmes JW. Modifying the mechanics of healing infarcts: Is better the enemy of good? J Mol Cell Cardiol 2015; 93:115-24. [PMID: 26631496 DOI: 10.1016/j.yjmcc.2015.11.028] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/09/2015] [Accepted: 11/26/2015] [Indexed: 02/06/2023]
Abstract
Myocardial infarction (MI) is a major source of morbidity and mortality worldwide, with over 7 million people suffering infarctions each year. Heart muscle damaged during MI is replaced by a collagenous scar over a period of several weeks, and the mechanical properties of that scar tissue are a key determinant of serious post-MI complications such as infarct rupture, depression of heart function, and progression to heart failure. Thus, there is increasing interest in developing therapies that modify the structure and mechanics of healing infarct scar. Yet most prior attempts at therapeutic scar modification have failed, some catastrophically. This article reviews available information about the mechanics of healing infarct scar and the functional impact of scar mechanical properties, and attempts to infer principles that can better guide future attempts to modify scar. One important conclusion is that collagen structure, mechanics, and remodeling of healing infarct scar vary so widely among experimental models that any novel therapy should be tested across a range of species, infarct locations, and reperfusion protocols. Another lesson from past work is that the biology and mechanics of healing infarcts are sufficiently complex that the effects of interventions are often counterintuitive; for example, increasing infarct stiffness has little effect on heart function, and inhibition of matrix metalloproteases (MMPs) has little effect on scar collagen content. Computational models can help explain such counterintuitive results, and are becoming an increasingly important tool for integrating known information to better identify promising therapies and design experiments to test them. Moving forward, potentially exciting new opportunities for therapeutic modification of infarct mechanics include modulating anisotropy and promoting scar compaction.
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Affiliation(s)
- Samantha A Clarke
- Department of Biomedical Engineering, University of Virginia, United States
| | - William J Richardson
- Department of Biomedical Engineering, University of Virginia, United States; Robert M. Berne Cardiovascular Research Center, University of Virginia, United States
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, University of Virginia, United States; Department of Medicine, University of Virginia, United States; Robert M. Berne Cardiovascular Research Center, University of Virginia, United States.
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17
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Altara R, Manca M, Sabra R, Eid AA, Booz GW, Zouein FA. Temporal cardiac remodeling post-myocardial infarction: dynamics and prognostic implications in personalized medicine. Heart Fail Rev 2015; 21:25-47. [PMID: 26498937 DOI: 10.1007/s10741-015-9513-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Despite dramatic improvements in short-term mortality rates following myocardial infarction (MI), long-term survival for MI patients who progress to heart failure remains poor. MI occurs when the left ventricle (LV) is deprived of oxygen for a sufficient period of time to induce irreversible necrosis of the myocardium. The LV response to MI involves significant tissue, cellular, and molecular level modifications, as well as substantial hemodynamic changes that feedback negatively to amplify the response. Inflammation to remove necrotic myocytes and fibroblast activation to form a scar are key wound healing responses that are highly variable across individuals. Few biomarkers of early remodeling stages are currently clinically adopted. The discovery of underlying pathophysiological mechanisms and associated novel biomarkers has the potential of improving prognostic capability and therapeutic monitoring. Combining these biomarkers with other prominent ones could constitute a powerful diagnostic and prognostic tool that directly reflects the pathophysiological remodeling of the LV. Understanding temporal remodeling at the tissue, cellular, and molecular level and its link to a well-defined set of biomarkers at early stages post-MI is a prerequisite for improving personalized care and devising more successful therapeutic interventions. Here we summarize the integral mechanisms that occur during early cardiac remodeling in the post-MI setting and highlight the most prominent biomarkers for assessing disease progression.
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Affiliation(s)
- Raffaele Altara
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Pharmacology and Toxicology, School of Medicine, University of Mississippi Medical Center, Jackson, MS, USA
| | - Marco Manca
- DG-DI, Medical Applications, CERN, Geneva, Switzerland
| | - Ramzi Sabra
- Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Assaad A Eid
- Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - George W Booz
- Department of Pharmacology and Toxicology, School of Medicine, University of Mississippi Medical Center, Jackson, MS, USA
| | - Fouad A Zouein
- Department of Pharmacology and Toxicology, School of Medicine, University of Mississippi Medical Center, Jackson, MS, USA. .,Department of Pharmacology and Toxicology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.
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18
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Richardson WJ, Holmes JW. Why Is Infarct Expansion Such an Elusive Therapeutic Target? J Cardiovasc Transl Res 2015; 8:421-30. [PMID: 26390882 PMCID: PMC4846979 DOI: 10.1007/s12265-015-9652-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 08/28/2015] [Indexed: 11/25/2022]
Abstract
Myocardial infarct expansion has been associated with an increased risk of infarct rupture and progression to heart failure, motivating therapies such as infarct restraint and polymer injection that aim to limit infarct expansion. However, an exhaustive review of quantitative studies of infarct remodeling reveals that only half found chronic in-plane expansion, and many reported in-plane compaction. Using a finite element model, we demonstrate that the balance between scar stiffening due to collagen accumulation and increased wall stresses due to infarct thinning can produce either expansion or compaction in the pressurized heart-potentially explaining variability in the literature-and that loaded dimensions are much more sensitive to changes in thickness than in stiffness. Our analysis challenges the concept that in-plane expansion is a central feature of post-infarction remodeling; rather, available data suggest that radial thinning is the dominant process during infarct healing and may be an attractive therapeutic target.
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Affiliation(s)
- William J Richardson
- Department of Biomedical Engineering, University of Virginia, Box 800759, Charlottesville, VA, 22908, USA.
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, USA.
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, University of Virginia, Box 800759, Charlottesville, VA, 22908, USA
- Department of Medicine, University of Virginia, Charlottesville, VA, USA
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, USA
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19
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Abstract
The heart pumps blood to maintain circulation and ensure the delivery of oxygenated blood to all the organs of the body. Mechanics play a critical role in governing and regulating heart function under both normal and pathological conditions. Biological processes and mechanical stress are coupled together in regulating myocyte function and extracellular matrix structure thus controlling heart function. Here, we offer a brief introduction to the biomechanics of left ventricular function and then summarize recent progress in the study of the effects of mechanical stress on ventricular wall remodeling and cardiac function as well as the effects of wall mechanical properties on cardiac function in normal and dysfunctional hearts. Various mechanical models to determine wall stress and cardiac function in normal and diseased hearts with both systolic and diastolic dysfunction are discussed. The results of these studies have enhanced our understanding of the biomechanical mechanism in the development and remodeling of normal and dysfunctional hearts. Biomechanics provide a tool to understand the mechanism of left ventricular remodeling in diastolic and systolic dysfunction and guidance in designing and developing new treatments.
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Affiliation(s)
- Andrew P. Voorhees
- Department of Mechanical Engineering, The University of Texas at San Antonio, Biomedical Engineering Program, UTSA-UTHSCSA
| | - Hai-Chao Han
- Department of Mechanical Engineering, The University of Texas at San Antonio, Biomedical Engineering Program, UTSA-UTHSCSA
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20
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Voorhees AP, DeLeon-Pennell KY, Ma Y, Halade GV, Yabluchanskiy A, Iyer RP, Flynn E, Cates CA, Lindsey ML, Han HC. Building a better infarct: Modulation of collagen cross-linking to increase infarct stiffness and reduce left ventricular dilation post-myocardial infarction. J Mol Cell Cardiol 2015; 85:229-39. [PMID: 26080361 PMCID: PMC4530076 DOI: 10.1016/j.yjmcc.2015.06.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Revised: 06/08/2015] [Accepted: 06/09/2015] [Indexed: 11/29/2022]
Abstract
Matrix metalloproteinase-9 (MMP-9) deletion attenuates collagen accumulation and dilation of the left ventricle (LV) post-myocardial infarction (MI); however the biomechanical mechanisms underlying the improved outcome are poorly understood. The aim of this study was to determine the mechanisms whereby MMP-9 deletion alters collagen network composition and assembly in the LV post-MI to modulate the mechanical properties of myocardial scar tissue. Adult C57BL/6J wild-type (WT; n=88) and MMP-9 null (MMP-9(-/-); n=92) mice of both sexes underwent permanent coronary artery ligation and were compared to day 0 controls (n=42). At day 7 post-MI, WT LVs displayed a 3-fold increase in end-diastolic volume, while MMP-9(-/-) showed only a 2-fold increase (p<0.05). Biaxial mechanical testing revealed that MMP-9(-/-) infarcts were stiffer than WT infarcts, as indicated by a 1.3-fold reduction in predicted in vivo circumferential stretch (p<0.05). Paradoxically, MMP-9(-/-) infarcts had a 1.8-fold reduction in collagen deposition (p<0.05). This apparent contradiction was explained by a 3.1-fold increase in lysyl oxidase (p<0.05) in MMP-9(-/-) infarcts, indicating that MMP-9 deletion increased collagen cross-linking activity. Furthermore, MMP-9 deletion led to a 3.0-fold increase in bone morphogenetic protein-1, the metalloproteinase that cleaves pro-collagen and pro-lysyl oxidase (p<0.05) and reduced fibronectin fragmentation by 49% (p<0.05) to enhance lysyl oxidase activity. We conclude that MMP-9 deletion increases infarct stiffness and prevents LV dilation by reducing collagen degradation and facilitating collagen assembly and cross-linking through preservation of the fibronectin network and activation of lysyl oxidase.
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Affiliation(s)
- Andrew P Voorhees
- Department of Mechanical Engineering, The University of Texas at San Antonio, USA; Joint Biomedical Engineering Program, UTSA-UTHSCSA, USA; San Antonio Cardiovascular Proteomics Center, USA
| | - Kristine Y DeLeon-Pennell
- San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA
| | - Yonggang Ma
- San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA
| | - Ganesh V Halade
- San Antonio Cardiovascular Proteomics Center, USA; Division of Cardiovascular Disease, Department of Medicine, The University of Alabama at Birmingham, USA
| | - Andriy Yabluchanskiy
- San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA; Research Service, G.V. (Sonny) Montgomery Veterans Affairs Medical Center, USA
| | - Rugmani Padmanabhan Iyer
- San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA
| | - Elizabeth Flynn
- Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA
| | - Courtney A Cates
- Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA
| | - Merry L Lindsey
- Joint Biomedical Engineering Program, UTSA-UTHSCSA, USA; San Antonio Cardiovascular Proteomics Center, USA; Mississippi Center for Heart Research, Department of Physiology and Biophysics, University of Mississippi Medical Center, USA; Research Service, G.V. (Sonny) Montgomery Veterans Affairs Medical Center, USA
| | - Hai-Chao Han
- Department of Mechanical Engineering, The University of Texas at San Antonio, USA; Joint Biomedical Engineering Program, UTSA-UTHSCSA, USA; San Antonio Cardiovascular Proteomics Center, USA.
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21
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McGarvey JR, Mojsejenko D, Dorsey SM, Nikou A, Burdick JA, Gorman JH, Jackson BM, Pilla JJ, Gorman RC, Wenk JF. Temporal Changes in Infarct Material Properties: An In Vivo Assessment Using Magnetic Resonance Imaging and Finite Element Simulations. Ann Thorac Surg 2015; 100:582-9. [PMID: 26095107 DOI: 10.1016/j.athoracsur.2015.03.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 03/06/2015] [Accepted: 03/10/2015] [Indexed: 11/26/2022]
Abstract
BACKGROUND Infarct expansion initiates and sustains adverse left ventricular (LV) remodeling after myocardial infarction (MI) and is influenced by temporal changes in infarct material properties. Data from ex vivo biaxial extension testing support this hypothesis; however, infarct material properties have never been measured in vivo. The goal of the current study was to serially quantify the in vivo material properties and fiber orientation of infarcted myocardium over a 12-week period in a porcine model of MI. METHODS A combination of magnetic resonance imaging (MRI), catheterization, finite element modeling, and numeric optimization was used to analyze posterolateral MI. Specifically, properties were determined by minimizing the difference between in vivo strains and volume calculated from MRI and strains and volume predicted by finite element modeling. RESULTS In 1 week after MI, the infarct region was found to be approximately 20 times stiffer than normal diastolic myocardium. Over the course of 12 weeks, the infarct region became progressively less stiff as the LV dilated and ejection fraction decreased. The infarct thinned by nearly half during the remodeling period, and infarct fiber angles became more circumferentially oriented. CONCLUSIONS The results reported here are consistent with previously described ex vivo biaxial extension studies of infarct material properties and the circumferential change of collagen orientation in posterolateral infarcts. The current study represents a significant advance in that the method used allows for the serial assessment of an individual infarct in vivo over time and avoids the inherent limitations related to the testing of excised tissues.
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Affiliation(s)
- Jeremy R McGarvey
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | | | - Shauna M Dorsey
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Amir Nikou
- Department of Mechanical Engineering, Lexington, Kentucky
| | - Jason A Burdick
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Benjamin M Jackson
- Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - James J Pilla
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jonathan F Wenk
- Department of Mechanical Engineering, Lexington, Kentucky; Department of Surgery, University of Kentucky, Lexington, Kentucky.
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22
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Rodell CB, MacArthur JW, Dorsey SM, Wade RJ, Wang LL, Woo YJ, Burdick JA. Shear-Thinning Supramolecular Hydrogels with Secondary Autonomous Covalent Crosslinking to Modulate Viscoelastic Properties In Vivo. ADVANCED FUNCTIONAL MATERIALS 2015; 25:636-644. [PMID: 26526097 PMCID: PMC4624407 DOI: 10.1002/adfm.201403550] [Citation(s) in RCA: 217] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Clinical percutaneous delivery of synthetically engineered hydrogels remains limited due to challenges posed by crosslinking kinetics - too fast leads to delivery failure, too slow limits material retention. To overcome this challenge, we exploit supramolecular assembly to localize hydrogels at the injection site and introduce subsequent covalent crosslinking to control final material properties. Supramolecular gels were designed through the separate pendant modifications of hyaluronic acid (HA) by the guest-host pair cyclodextrin and adamantane, enabling shear-thinning injection and high target site retention (>98%). Secondary covalent crosslinking occurred via addition of thiols and Michael-acceptors (i.e., methacrylates, acrylates, vinyl sulfones) on HA and increased hydrogel moduli (E=25.0±4.5kPa) and stability (>3.5 fold in vivo at 28 days). Application of the dual-crosslinking hydrogel to a myocardial infarct model showed improved outcomes relative to untreated and supramolecular hydrogel alone controls, demonstrating its potential in a range of applications where the precise delivery of hydrogels with tunable properties is desired.
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Affiliation(s)
- Christopher B. Rodell
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, United States
| | - John W. MacArthur
- Division of Cardiovascular Surgery, Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, 19104, United States
| | - Shauna M. Dorsey
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, United States
| | - Ryan J. Wade
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, United States
- Department of Materials Science, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, United States
| | - Leo L. Wang
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, United States
| | - Y. Joseph Woo
- Department of Cardio-Thoracic Surgery, Stanford University School of Medicine, Stanford, California, 94305, United States
| | - Jason A. Burdick
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, United States
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Hypoxia training attenuates left ventricular remodeling in rabbit with myocardial infarction. JOURNAL OF GERIATRIC CARDIOLOGY : JGC 2014; 11:237-44. [PMID: 25278973 PMCID: PMC4178516 DOI: 10.11909/j.issn.1671-5411.2014.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 05/12/2014] [Accepted: 06/10/2014] [Indexed: 11/21/2022]
Abstract
Objective Previous studies showed that hypoxia preconditioning could protect cardiac function against subsequent myocardial infarction injury. However, the effect of hypoxia on left ventricular after myocardial infarction is still unclear. This study therefore aims to investigate the effects of hypoxia training on left ventricular remodeling in rabbits post myocardial infarction. Methods Adult male rabbits were randomly divided into three groups: group SO (sham operated), group MI (myocardial infarction only) and group MI-HT (myocardial infarction plus hypoxia training). Myocardial infarction was induced by left ventricular branch ligation. Hypoxia training was performed in a hypobaric chamber (having equivalent condition at an altitude of 4000 m, FiO214.9%) for 1 h/day, 5 days/week for four weeks. At the endpoints, vascular endothelial growth factor (VEGF) in the plasma was measured. Infarct size and capillary density were detected by histology. Left ventricular remodeling and function were assessed by echocardiography. Results After the 4-week experiment, compared with the group SO, plasma VEGF levels in groups MI (130.27 ± 18.58 pg/mL, P < 0.01) and MI-HT (181.93 ± 20.29 pg/mL, P < 0.01) were significantly increased. Infarct size in Group MI-HT (29.67% ± 7.73%) was deceased remarkably, while its capillary density (816.0 ± 122.2/mm2) was significantly increased. For both groups MI and MI-HT, left ventricular end-diastolic and end-systolic dimensions were increased whereas left ventricular ejection fraction was decreased. However, compared with group MI, group MI-HT diminished left ventricular end-diastolic (15.86 ± 1.09 mm, P < 0.05) and end-systolic dimensions (12.10 ± 1.20 mm, P < 0.01) significantly and improved left ventricular ejection fraction (54.39 ± 12.74 mm, P < 0.05). Conclusion Hypoxia training may improve left ventricular function and reduce remodeling via angiogenesis in rabbits with MI.
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Rouillard AD, Holmes JW. Coupled agent-based and finite-element models for predicting scar structure following myocardial infarction. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:235-43. [PMID: 25009995 DOI: 10.1016/j.pbiomolbio.2014.06.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 06/28/2014] [Indexed: 01/19/2023]
Abstract
Following myocardial infarction, damaged muscle is gradually replaced by collagenous scar tissue. The structural and mechanical properties of the scar are critical determinants of heart function, as well as the risk of serious post-infarction complications such as infarct rupture, infarct expansion, and progression to dilated heart failure. A number of therapeutic approaches currently under development aim to alter infarct mechanics in order to reduce complications, such as implantation of mechanical restraint devices, polymer injection, and peri-infarct pacing. Because mechanical stimuli regulate scar remodeling, the long-term consequences of therapies that alter infarct mechanics must be carefully considered. Computational models have the potential to greatly improve our ability to understand and predict how such therapies alter heart structure, mechanics, and function over time. Toward this end, we developed a straightforward method for coupling an agent-based model of scar formation to a finite-element model of tissue mechanics, creating a multi-scale model that captures the dynamic interplay between mechanical loading, scar deformation, and scar material properties. The agent-based component of the coupled model predicts how fibroblasts integrate local chemical, structural, and mechanical cues as they deposit and remodel collagen, while the finite-element component predicts local mechanics at any time point given the current collagen fiber structure and applied loads. We used the coupled model to explore the balance between increasing stiffness due to collagen deposition and increasing wall stress due to infarct thinning and left ventricular dilation during the normal time course of healing in myocardial infarcts, as well as the negative feedback between strain anisotropy and the structural anisotropy it promotes in healing scar. The coupled model reproduced the observed evolution of both collagen fiber structure and regional deformation following coronary ligation in the rat, and suggests that fibroblast alignment in the direction of greatest stretch provides negative feedback on the level of anisotropy in a scar forming under load. In the future, this coupled model may prove useful in computational design and screening of novel therapies to influence scar formation in mechanically loaded tissues.
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Affiliation(s)
- Andrew D Rouillard
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, USA
| | - Jeffrey W Holmes
- Department of Biomedical Engineering, Department of Medicine, Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA.
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25
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Voorhees AP, Han HC. A model to determine the effect of collagen fiber alignment on heart function post myocardial infarction. Theor Biol Med Model 2014; 11:6. [PMID: 24456675 PMCID: PMC3914851 DOI: 10.1186/1742-4682-11-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Accepted: 01/08/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Adverse remodeling of the left ventricle (LV) following myocardial infarction (MI) leads to heart failure. Recent studies have shown that scar anisotropy is a determinant of cardiac function post-MI, however it remains unclear how changes in extracellular matrix (ECM) organization and structure contribute to changes in LV function. The objective of this study is to develop a model to identify potential mechanisms by which collagen structure and organization affect LV function post-MI. METHODS A four-region, multi-scale, cylindrical model of the post-MI LV was developed. The mechanical properties of the infarct region are governed by a constitutive equation based on the uncrimping of collagen fibers. The parameters of this constitutive equation include collagen orientation, angular dispersion, fiber stiffness, crimp angle, and density. Parametric variation of these parameters was used to elucidate the relationship between collagen properties and LV function. RESULTS The mathematical model of the LV revealed several factors that influenced cardiac function post-MI. LV function was maximized when collagen fibers were aligned longitudinally. Increased collagen density was also found to improve stroke volume for longitudinal alignments while increased fiber stiffness decreased stroke volume for circumferential alignments. CONCLUSIONS The results suggest that cardiac function post-MI is best preserved through increased circumferential compliance. Further, this study identifies several collagen fiber-level mechanisms that could potentially regulate both infarct level and organ level mechanics. Improved understanding of the multi-scale relationships between the ECM and LV function will be beneficial in the design of new diagnostic and therapeutic technologies.
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Affiliation(s)
- Andrew P Voorhees
- Biomedical Engineering Program, UTSA-UTHSCSA 1 UTSA Circle, San Antonio, TX 78249, USA
| | - Hai-Chao Han
- Biomedical Engineering Program, UTSA-UTHSCSA 1 UTSA Circle, San Antonio, TX 78249, USA
- Department of Mechanical Engineering, The University of Texas at San Antonio Biomedical Engineering Program, UTSA-UTHSCSA, 1 UTSA Circle, San Antonio, TX 78249, USA
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26
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Dai W, Kay GL, Kloner RA. The Therapeutic Effect of Cell Transplantation Versus Noncellular Biomaterial Implantation on Cardiac Structure and Function Following Myocardial Infarction. J Cardiovasc Pharmacol Ther 2014; 19:350-357. [DOI: 10.1177/1074248413517746] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Although numerous studies demonstrated that localized delivery of either cells or biomaterials improved postinfarction cardiac function, the underlying mechanisms for this effect remain unclear. We performed a comparison of the effects of fetal, neonatal, and human embryonic stem cell-derived cardiac cell as well as mesenchymal stem cell transplantation versus biomaterial (collagen/extracellular matrix) implantation therapy in rat myocardial infarction model in our laboratory, specifically comparing their effects on infarct wall thickness, neovascularization, infarct wall motion, and left ventricular ejection fraction (LVEF). Both cell and biomaterial treatment had similar beneficial effects on cardiac structure (increasing infarct wall thickness and preventing infarct expansion) and function (preventing paradoxical LV systolic bulging and improving LVEF). In this review, we also discussed the underlying mechanisms of cell and biomaterial therapies, their advantages and disadvantages, and future research directions in the field of regenerative cardiology.
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Affiliation(s)
- Wangde Dai
- The Heart Institute, Good Samaritan Hospital, and Division of Cardiovascular Medicine of the Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Gregory L. Kay
- The Heart Institute, Good Samaritan Hospital, and Division of Cardiovascular Medicine of the Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Robert A. Kloner
- The Heart Institute, Good Samaritan Hospital, and Division of Cardiovascular Medicine of the Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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27
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Shuman JA, Zurcher JR, Sapp AA, Burdick JA, Gorman RC, Gorman JH, Goldsmith EC, Spinale FG. Localized targeting of biomaterials following myocardial infarction: a foundation to build on. Trends Cardiovasc Med 2013; 23:301-11. [PMID: 23746937 DOI: 10.1016/j.tcm.2013.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 04/05/2013] [Accepted: 04/08/2013] [Indexed: 01/01/2023]
Abstract
Acute coronary syndromes can give rise to myocardial injury infarction (MI), which in turn promulgates a series of cellular and extracellular events that result in left ventricular (LV) dilation and dysfunction. Localized strategies focused upon interrupting this inexorable process include delivery of bioactive molecules and stem cell derivatives. These localized treatment strategies are often delivered in a biomaterial complex in order to facilitate elution of the bioactive molecules or stem cell engraftment. However, these biomaterials can impart significant and independent effects upon the MI remodeling process. In addition, significant changes in local cell and interstitial biology within the targeted MI region can occur following injection of certain biomaterials, which may hold important considerations when using these materials as matrices for adjuvant drug/cell therapies.
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Affiliation(s)
- James A Shuman
- Cardiovascular Translational Research Center, University of South Carolina School of Medicine, Columbia, SC, USA
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28
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Neal RA, Jean A, Park H, Wu PB, Hsiao J, Engelmayr GC, Langer R, Freed LE. Three-dimensional elastomeric scaffolds designed with cardiac-mimetic structural and mechanical features. Tissue Eng Part A 2012. [PMID: 23190320 DOI: 10.1089/ten.tea.2012.0330] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Tissue-engineered constructs, at the interface of material science, biology, engineering, and medicine, have the capacity to improve outcomes for cardiac patients by providing living cells and degradable biomaterials that can regenerate the native myocardium. With an ultimate goal of both delivering cells and providing mechanical support to the healing heart, we designed three-dimensional (3D) elastomeric scaffolds with (1) stiffnesses and anisotropy mimicking explanted myocardial specimens as predicted by finite-element (FE) modeling, (2) systematically varied combinations of rectangular pore pattern, pore aspect ratio, and strut width, and (3) structural features approaching tissue scale. Based on predicted mechanical properties, three scaffold designs were selected from eight candidates for fabrication from poly(glycerol sebacate) by micromolding from silicon wafers. Large 20×20 mm scaffolds with high aspect ratio features (5:1 strut height:strut width) were reproducibly cast, cured, and demolded at a relatively high throughput. Empirically measured mechanical properties demonstrated that scaffolds were cardiac mimetic and validated FE model predictions. Two-layered scaffolds providing fully interconnected pore networks were fabricated by layer-by-layer assembly. C2C12 myoblasts cultured on one-layered scaffolds exhibited specific patterns of cell elongation and interconnectivity that appeared to be guided by the scaffold pore pattern. Neonatal rat heart cells cultured on two-layered scaffolds for 1 week were contractile, both spontaneously and in response to electrical stimulation, and expressed sarcomeric α-actinin, a cardiac biomarker. This work not only demonstrated several scaffold designs that promoted functional assembly of rat heart cells, but also provided the foundation for further computational and empirical investigations of 3D elastomeric scaffolds for cardiac tissue engineering.
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Affiliation(s)
- Rebekah A Neal
- Harvard-MIT Division of Health Sciences and Technology, David H. Koch Institute for Integrative Cancer Research, and Institute for Medical Engineering and Science, Massachusetts Institute of Technology , Cambridge, Massachusetts, USA
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Fomovsky GM, Clark SA, Parker KM, Ailawadi G, Holmes JW. Anisotropic reinforcement of acute anteroapical infarcts improves pump function. Circ Heart Fail 2012; 5:515-22. [PMID: 22665716 DOI: 10.1161/circheartfailure.111.965731] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND We hypothesize that a therapy that improves left ventricular (LV) pump function early after infarction should decrease the need for compensation through sympathetic activation and dilation, thereby reducing the risk of developing heart failure. The mechanical properties of healing myocardial infarcts are an important determinant of LV function, yet improving function by altering infarct properties has proven unexpectedly difficult. Using a computational model, we recently predicted that stiffening a large anterior infarct anisotropically (in only one direction) would improve LV function, whereas isotropic stiffening, the focus of previous studies and therapies, would not. The goal of this study was to test the novel strategy of anisotropic infarct reinforcement. METHODS AND RESULTS We tested the effects of anisotropic infarct reinforcement in 10 open-chest dogs with large anteroapical infarcts that depressed LV pump function. We measured regional mechanics, LV volumes, and cardiac output at a range of preloads at baseline, 45 minutes after coronary ligation (ischemia), and 30 minutes later, after surgical reinforcement in the longitudinal direction (anisotropic). Ischemia shifted the end-systolic pressure-volume relationship and cardiac output curves rightward, decreasing cardiac output at matched end-diastolic pressure by 44%. Anisotropic reinforcement significantly improved systolic function without impairing diastolic function, recovering half the deficit in overall LV function. CONCLUSIONS We conclude that anisotropic reinforcement is a promising new approach to improving LV function after a large myocardial infarction.
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Affiliation(s)
- Gregory M Fomovsky
- Departments of Biomedical Engineering, Medicine, and Surgery and the Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
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Zouein FA, Zgheib C, Liechty KW, Booz GW. Post-infarct biomaterials, left ventricular remodeling, and heart failure: is good good enough? ACTA ACUST UNITED AC 2012; 18:284-90. [PMID: 22612796 DOI: 10.1111/j.1751-7133.2012.00298.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Fouad A Zouein
- Department of Pharmacology and Toxicology,the Department of Surgery, The Center for Excellence in Cardiovascular-Renal Research, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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Regional mechanics determine collagen fiber structure in healing myocardial infarcts. J Mol Cell Cardiol 2012; 52:1083-90. [PMID: 22418281 DOI: 10.1016/j.yjmcc.2012.02.012] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Revised: 02/10/2012] [Accepted: 02/28/2012] [Indexed: 11/20/2022]
Abstract
Following myocardial infarction, the mechanical properties of the healing infarct are an important determinant of heart function and the risk of progression to heart failure. In particular, mechanical anisotropy (having different mechanical properties in different directions) in the healing infarct can preserve pump function of the heart. Based on reports of different collagen structures and mechanical properties in various animal models, we hypothesized that differences in infarct size, shape, and/or location produce different patterns of mechanical stretch that guide evolving collagen fiber structure. We tested the effects of infarct shape and location using a combined experimental and computational approach. We studied mechanics and collagen fiber structure in cryoinfarcts in 53 Sprague-Dawley rats and found that regardless of shape or orientation, cryoinfarcts near the equator of the left ventricle stretched primarily in the circumferential direction and developed circumferentially aligned collagen, while infarcts at the apex stretched similarly in the circumferential and longitudinal directions and developed randomly oriented collagen. In a computational model of infarct healing, an effect of mechanical stretch on fibroblast and collagen alignment was required to reproduce the experimental results. We conclude that mechanical environment determines collagen fiber structure in healing myocardial infarcts. Our results suggest that emerging post-infarction therapies that alter regional mechanics will also alter infarct collagen structure, offering both potential risks and novel therapeutic opportunities.
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Myocardial tissue elastic properties determined by atomic force microscopy after stromal cell-derived factor 1α angiogenic therapy for acute myocardial infarction in a murine model. J Thorac Cardiovasc Surg 2012; 143:962-6. [PMID: 22264415 DOI: 10.1016/j.jtcvs.2011.12.028] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 11/22/2011] [Accepted: 12/14/2011] [Indexed: 01/26/2023]
Abstract
OBJECTIVES Ventricular remodeling after myocardial infarction begins with massive extracellular matrix deposition and resultant fibrosis. This loss of functional tissue and stiffening of myocardial elastic and contractile elements starts the vicious cycle of mechanical inefficiency, adverse remodeling, and eventual heart failure. We hypothesized that stromal cell-derived factor 1α (SDF-1α) therapy to microrevascularize ischemic myocardium would rescue salvageable peri-infarct tissue and subsequently improve myocardial elasticity. METHODS Immediately after left anterior descending coronary artery ligation, mice were randomly assigned to receive peri-infarct injection of either saline solution or SDF-1α. After 6 weeks, animals were killed and samples were taken from the peri-infarct border zone and the infarct scar, as well as from the left ventricle of noninfarcted control mice. Determination of tissues' elastic moduli was carried out by mechanical testing in an atomic force microscope. RESULTS SDF-1α-treated peri-infarct tissue most closely approximated the elasticity of normal ventricle and was significantly more elastic than saline-treated peri-infarct myocardium (109 ± 22.9 kPa vs 295 ± 42.3 kPa; P < .0001). Myocardial scar, the strength of which depends on matrix deposition from vasculature at the peri-infarct edge, was stiffer in SDF-1α-treated animals than in controls (804 ± 102.2 kPa vs 144 ± 27.5 kPa; P < .0001). CONCLUSIONS Direct quantification of myocardial elastic properties demonstrates the ability of SDF-1α to re-engineer evolving myocardial infarct and peri-infarct tissues. By increasing elasticity of the ischemic and dysfunctional peri-infarct border zone and bolstering the weak, aneurysm-prone scar, SDF-1α therapy may confer a mechanical advantage to resist adverse remodeling after infarction.
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