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Motchon YD, Sack KL, Sirry MS, Nchejane NJ, Abdalrahman T, Nagawa J, Kruger M, Pauwels E, Van Loo D, De Muynck A, Van Hoorebeke L, Davies NH, Franz T. In silico Mechanics of Stem Cells Intramyocardially Transplanted with a Biomaterial Injectate for Treatment of Myocardial Infarction. Cardiovasc Eng Technol 2024:10.1007/s13239-024-00734-1. [PMID: 38782879 DOI: 10.1007/s13239-024-00734-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 05/12/2024] [Indexed: 05/25/2024]
Abstract
PURPOSE Biomaterial and stem cell delivery are promising approaches to treating myocardial infarction. However, the mechanical and biochemical mechanisms underlying the therapeutic benefits require further clarification. This study aimed to assess the deformation of stem cells injected with the biomaterial into the infarcted heart. METHODS A microstructural finite element model of a mid-wall infarcted myocardial region was developed from ex vivo microcomputed tomography data of a rat heart with left ventricular infarct and intramyocardial biomaterial injectate. Nine cells were numerically seeded in the injectate of the microstructural model. The microstructural and a previously developed biventricular finite element model of the same rat heart were used to quantify the deformation of the cells during a cardiac cycle for a biomaterial elastic modulus (Einj) ranging between 4.1 and 405,900 kPa. RESULTS The transplanted cells' deformation was largest for Einj = 7.4 kPa, matching that of the cells, and decreased for an increase and decrease in Einj. The cell deformation was more sensitive to Einj changes for softer (Einj ≤ 738 kPa) than stiffer biomaterials. CONCLUSIONS Combining the microstructural and biventricular finite element models enables quantifying micromechanics of transplanted cells in the heart. The approach offers a broader scope for in silico investigations of biomaterial and cell therapies for myocardial infarction and other cardiac pathologies.
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Affiliation(s)
- Y D Motchon
- Biomedical Engineering Research Centre, Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Observatory, South Africa.
| | - K L Sack
- Biomedical Engineering Research Centre, Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Observatory, South Africa
- Cardiac Rhythm Management, Medtronic Inc, Minneapolis, MN, USA
| | - M S Sirry
- Biomedical Engineering Research Centre, Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Observatory, South Africa
- Department of Biomedical Engineering, School of Engineering and Computing, American International University, Al Jahra, Kuwait
| | - N J Nchejane
- Biomedical Engineering Research Centre, Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Observatory, South Africa
| | - T Abdalrahman
- Biomedical Engineering Research Centre, Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Observatory, South Africa
| | - J Nagawa
- Biomedical Engineering Research Centre, Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Observatory, South Africa
| | - M Kruger
- Cardiovascular Research Unit, University of Cape Town, Observatory, South Africa
| | - E Pauwels
- Centre for X-ray Tomography, Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - D Van Loo
- Centre for X-ray Tomography, Department of Physics and Astronomy, Ghent University, Ghent, Belgium
- XRE nv, Bollebergen 2B box 1, Ghent, 9052, Belgium
| | - A De Muynck
- Centre for X-ray Tomography, Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - L Van Hoorebeke
- Centre for X-ray Tomography, Department of Physics and Astronomy, Ghent University, Ghent, Belgium
| | - N H Davies
- Cardiovascular Research Unit, University of Cape Town, Observatory, South Africa
| | - T Franz
- Biomedical Engineering Research Centre, Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Observatory, South Africa.
- Bioengineering Science Research Group, Department of Mechanical Engineering, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK.
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Motchon YD, Sack KL, Sirry MS, Kruger M, Pauwels E, Van Loo D, De Muynck A, Van Hoorebeke L, Davies NH, Franz T. Effect of biomaterial stiffness on cardiac mechanics in a biventricular infarcted rat heart model with microstructural representation of in situ intramyocardial injectate. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2023; 39:e3693. [PMID: 36864599 PMCID: PMC10909490 DOI: 10.1002/cnm.3693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 11/19/2022] [Accepted: 01/29/2023] [Indexed: 05/13/2023]
Abstract
Intramyocardial delivery of biomaterials is a promising concept for treating myocardial infarction. The delivered biomaterial provides mechanical support and attenuates wall thinning and elevated wall stress in the infarct region. This study aimed at developing a biventricular finite element model of an infarcted rat heart with a microstructural representation of an in situ biomaterial injectate, and a parametric investigation of the effect of the injectate stiffness on the cardiac mechanics. A three-dimensional subject-specific biventricular finite element model of a rat heart with left ventricular infarct and microstructurally dispersed biomaterial delivered 1 week after infarct induction was developed from ex vivo microcomputed tomography data. The volumetric mesh density varied between 303 mm-3 in the myocardium and 3852 mm-3 in the injectate region due to the microstructural intramyocardial dispersion. Parametric simulations were conducted with the injectate's elastic modulus varying from 4.1 to 405,900 kPa, and myocardial and injectate strains were recorded. With increasing injectate stiffness, the end-diastolic median myocardial fibre and cross-fibre strain decreased in magnitude from 3.6% to 1.1% and from -6.0% to -2.9%, respectively. At end-systole, the myocardial fibre and cross-fibre strain decreased in magnitude from -20.4% to -11.8% and from 6.5% to 4.6%, respectively. In the injectate, the maximum and minimum principal strains decreased in magnitude from 5.4% to 0.001% and from -5.4% to -0.001%, respectively, at end-diastole and from 38.5% to 0.06% and from -39.0% to -0.06%, respectively, at end-systole. With the microstructural injectate geometry, the developed subject-specific cardiac finite element model offers potential for extension to cellular injectates and in silico studies of mechanotransduction and therapeutic signalling in the infarcted heart with an infarct animal model extensively used in preclinical research.
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Affiliation(s)
- Y. D. Motchon
- Biomedical Engineering Research Centre, Division of Biomedical Engineering, Department of Human BiologyUniversity of Cape TownCape TownSouth Africa
| | - Kevin L. Sack
- Biomedical Engineering Research Centre, Division of Biomedical Engineering, Department of Human BiologyUniversity of Cape TownCape TownSouth Africa
- Department of SurgeryUniversity of California at San FranciscoSan FranciscoCaliforniaUSA
| | - M. S. Sirry
- Department of Biomedical Engineering, School of Engineering and ComputingAmerican International UniversityAl JahraKuwait
| | - M. Kruger
- Cardiovascular Research Unit, MRC IUCHRUUniversity of Cape TownCape TownSouth Africa
| | - E. Pauwels
- Centre for X‐ray Tomography, Department of Physics and AstronomyGhent UniversityGhentBelgium
- Nuclear MedicineUniversity Hospitals LeuvenLeuvenBelgium
| | - D. Van Loo
- Centre for X‐ray Tomography, Department of Physics and AstronomyGhent UniversityGhentBelgium
- XRE nv, Bollebergen 2B box 1, 9052GhentBelgium
| | - A. De Muynck
- Centre for X‐ray Tomography, Department of Physics and AstronomyGhent UniversityGhentBelgium
| | - L. Van Hoorebeke
- Centre for X‐ray Tomography, Department of Physics and AstronomyGhent UniversityGhentBelgium
| | - Neil H. Davies
- Cardiovascular Research Unit, MRC IUCHRUUniversity of Cape TownCape TownSouth Africa
| | - Thomas Franz
- Biomedical Engineering Research Centre, Division of Biomedical Engineering, Department of Human BiologyUniversity of Cape TownCape TownSouth Africa
- Bioengineering Science Research Group, Faculty of Engineering and Physical SciencesUniversity of SouthamptonSouthamptonUK
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Leong CO, Leong CN, Liew YM, Al Abed A, Aziz YFA, Chee KH, Sridhar GS, Dokos S, Lim E. The role of regional myocardial topography post-myocardial infarction on infarct extension. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3501. [PMID: 34057819 DOI: 10.1002/cnm.3501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 04/26/2021] [Accepted: 05/28/2021] [Indexed: 06/12/2023]
Abstract
Infarct extension involves necrosis of healthy myocardium in the border zone (BZ), progressively enlarging the infarct zone (IZ) and recruiting the remote zone (RZ) into the BZ, eventually leading to heart failure. The mechanisms underlying infarct extension remain unclear, but myocyte stretching has been suggested as the most likely cause. Using human patient-specific left-ventricular (LV) numerical simulations established from cardiac magnetic resonance imaging (MRI) of myocardial infarction (MI) patients, the correlation between infarct extension and regional mechanics abnormality was investigated by analysing the fibre stress-strain loops (FSSLs). FSSL abnormality was characterised using the directional regional external work (DREW) index, which measures FSSL area and loop direction. Sensitivity studies were also performed to investigate the effect of infarct stiffness on regional myocardial mechanics and potential for infarct extension. We found that infarct extension was correlated to severely abnormal FSSL in the form of counter-clockwise loop at the RZ close to the infarct, as indicated by negative DREW values. In regions demonstrating negative DREW values, we observed substantial fibre stretching in the isovolumic relaxation (IVR) phase accompanied by a reduced rate of systolic shortening. Such stretching in IVR phase in part of the RZ was due to its inability to withstand the high LV pressure that was still present and possibly caused by regional myocardial stiffness inhomogeneity. Further analysis revealed that the occurrence of severely abnormal FSSL due to IVR fibre stretching near the RZ-BZ boundary was due to a large amount of surrounding infarcted tissue, or an excessively stiff IZ.
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Affiliation(s)
- Chen Onn Leong
- Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
| | - Chin Neng Leong
- Graduate School of Biomedical Engineering, Faculty of Engineering, University of New South Wales, Sydney, New South Wales, Australia
| | - Yih Miin Liew
- Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
| | - Amr Al Abed
- Graduate School of Biomedical Engineering, Faculty of Engineering, University of New South Wales, Sydney, New South Wales, Australia
| | - Yang Faridah Abdul Aziz
- Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
- University Malaya Research Imaging Centre, University of Malaya, Kuala Lumpur, Malaysia
| | - Kok Han Chee
- Department of Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | | | - Socrates Dokos
- Graduate School of Biomedical Engineering, Faculty of Engineering, University of New South Wales, Sydney, New South Wales, Australia
| | - Einly Lim
- Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
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Matsumura Y, Zhu Y, Jiang H, D'Amore A, Luketich SK, Charwat V, Yoshizumi T, Sato H, Yang B, Uchibori T, Healy KE, Wagner WR. Intramyocardial injection of a fully synthetic hydrogel attenuates left ventricular remodeling post myocardial infarction. Biomaterials 2019; 217:119289. [DOI: 10.1016/j.biomaterials.2019.119289] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/08/2019] [Accepted: 06/17/2019] [Indexed: 12/27/2022]
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Ngoepe M, Passos A, Balabani S, King J, Lynn A, Moodley J, Swanson L, Bezuidenhout D, Davies NH, Franz T. A Preliminary Computational Investigation Into the Flow of PEG in Rat Myocardial Tissue for Regenerative Therapy. Front Cardiovasc Med 2019; 6:104. [PMID: 31448288 PMCID: PMC6692440 DOI: 10.3389/fcvm.2019.00104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 07/16/2019] [Indexed: 11/30/2022] Open
Abstract
Myocardial infarction (MI), a type of cardiovascular disease, affects a significant proportion of people around the world. Traditionally, non-communicable chronic diseases were largely associated with aging populations in higher income countries. It is now evident that low- to middle-income countries are also affected and in these settings, younger individuals are at high risk. Currently, interventions for MI prolong the time to heart failure. Regenerative medicine and stem cell therapy have the potential to mitigate the effects of MI and to significantly improve the quality of life for patients. The main drawback with these therapies is that many of the injected cells are lost due to the vigorous motion of the heart. Great effort has been directed toward the development of scaffolds which can be injected alongside stem cells, in an attempt to improve retention and cell engraftment. In some cases, the scaffold alone has been seen to improve heart function. This study focuses on a synthetic polyethylene glycol (PEG) based hydrogel which is injected into the heart to improve left ventricular function following MI. Many studies in literature characterize PEG as a Newtonian fluid within a specified shear rate range, on the macroscale. The aim of the study is to characterize the flow of a 20 kDa PEG on the microscale, where the behavior is likely to deviate from macroscale flow patterns. Micro particle image velocimetry (μPIV) is used to observe flow behavior in microchannels, representing the gaps in myocardial tissue. The fluid exhibits non-Newtonian, shear-thinning behavior at this scale. Idealized two-dimensional computational fluid dynamics (CFD) models of PEG flow in microchannels are then developed and validated using the μPIV study. The validated computational model is applied to a realistic, microscopy-derived myocardial tissue model. From the realistic tissue reconstruction, it is evident that the myocardial flow region plays an important role in the distribution of PEG, and therefore, in the retention of material.
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Affiliation(s)
- Malebogo Ngoepe
- Department of Mechanical Engineering, University of Cape Town, Rondebosch, South Africa.,Wallenberg Research Centre, Stellenbosch Institute of Advanced Study, Stellenbosch University, Stellenbosch, South Africa
| | - Andreas Passos
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Stavroula Balabani
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Jesse King
- Department of Mechanical Engineering, University of Cape Town, Rondebosch, South Africa
| | - Anastasia Lynn
- Department of Mechanical Engineering, University of Cape Town, Rondebosch, South Africa
| | - Jasanth Moodley
- Department of Mechanical Engineering, University of Cape Town, Rondebosch, South Africa
| | - Liam Swanson
- Department of Mechanical Engineering, University of Cape Town, Rondebosch, South Africa
| | - Deon Bezuidenhout
- Cardiovascular Research Unit, Department of Surgery, University of Cape Town, Observatory, South Africa
| | - Neil H Davies
- Cardiovascular Research Unit, Department of Surgery, University of Cape Town, Observatory, South Africa
| | - Thomas Franz
- Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Observatory, South Africa.,Bioengineering Science Research Group, Engineering Sciences, Faculty of Engineering and the Environment, University of Southampton, Southampton, United Kingdom
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Nemavhola F. Fibrotic infarction on the LV free wall may alter the mechanics of healthy septal wall during passive filling. Biomed Mater Eng 2017; 28:579-599. [PMID: 29171965 DOI: 10.3233/bme-171698] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The effect of myocardial infarction on the global functioning of the heart is well known. Less is understood regarding the effect of LV fibrotic infarction on the cardiac mechanics of the septal wall. To determine this unknown, the stress and strain of septal wall on the healthy and infarcted rat heart model is measured by using finite element models of rat heart geometries. The main objective of this study was to utilized computational methods to study the effect of LV free wall fibrotic infarction on the healthy septal wall. Three-dimensional biventricular rat heart geometries were developed from cardiac magnetic resonance images of a healthy heart and a heart with left ventricular (LV) fibrotic infarction after infarct induction. From these geometries, FE models were established. Three-dimensional biventricular rat heart geometries developed from cardiac magnetic resonance images were used in creating FE models of healthy and infarcted rat hearts. The average radial strain percentage change of the healthy septal wall on the epicardium, mid-wall and endocardium was 61%, 52% and 14% higher than the infarcted septal wall, respectively. It was concluded that the fibrotic infarction has a potential cause the malfunction of the heart due to high myocardial stress and strain that the septal wall experiences.
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Affiliation(s)
- Fulufhelo Nemavhola
- Department of Mechanical and Industrial Engineering, College of science, Engineering and Technology, University of South Africa, Florida, 1710, South Africa. Tel.: +27 (0)11 471 2765; Fax: +27 (0)11 471 2963; E-mail:
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7
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Wang H, Rodell CB, Lee ME, Dusaj NN, Gorman JH, Burdick JA, Gorman RC, Wenk JF. Computational sensitivity investigation of hydrogel injection characteristics for myocardial support. J Biomech 2017; 64:231-235. [PMID: 28888476 DOI: 10.1016/j.jbiomech.2017.08.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/11/2017] [Accepted: 08/22/2017] [Indexed: 10/18/2022]
Abstract
Biomaterial injection is a potential new therapy for augmenting ventricular mechanics after myocardial infarction (MI). Recent in vivo studies have demonstrated that hydrogel injections can mitigate the adverse remodeling due to MI. More importantly, the material properties of these injections influence the efficacy of the therapy. The goal of the current study is to explore the interrelated effects of injection stiffness and injection volume on diastolic ventricular wall stress and thickness. To achieve this, finite element models were constructed with different hydrogel injection volumes (150µL and 300 µL), where the modulus was assessed over a range of 0.1kPa to 100kPa (based on experimental measurements). The results indicate that a larger injection volume and higher stiffness reduce diastolic myofiber stress the most, by maintaining the wall thickness during loading. Interestingly, the efficacy begins to taper after the hydrogel injection stiffness reaches a value of 50kPa. This computational approach could be used in the future to evaluate the optimal properties of the hydrogel.
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Affiliation(s)
- Hua Wang
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, United States
| | - Christopher B Rodell
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States
| | - Madonna E Lee
- Gorman Cardiovascular Research Group and Department of Surgery, University of Pennsylvania, Philadelphia, PA, United States
| | - Neville N Dusaj
- Departments of Chemistry and Physics, University of Pennsylvania, Philadelphia, PA, United States
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group and Department of Surgery, University of Pennsylvania, Philadelphia, PA, United States
| | - Jason A Burdick
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States
| | - Robert C Gorman
- Gorman Cardiovascular Research Group and Department of Surgery, University of Pennsylvania, Philadelphia, PA, United States
| | - Jonathan F Wenk
- Department of Mechanical Engineering, University of Kentucky, Lexington, KY, United States; Department of Surgery, University of Kentucky, Lexington, KY, United States.
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Zhu Y, Matsumura Y, Wagner WR. Ventricular wall biomaterial injection therapy after myocardial infarction: Advances in material design, mechanistic insight and early clinical experiences. Biomaterials 2017; 129:37-53. [PMID: 28324864 PMCID: PMC5827941 DOI: 10.1016/j.biomaterials.2017.02.032] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 02/07/2017] [Accepted: 02/26/2017] [Indexed: 12/11/2022]
Abstract
Intramyocardial biomaterial injection therapy for myocardial infarction has made significant progress since concept initiation more than 10 years ago. The interim successes and progress in the first 5 years have been extensively reviewed. During the last 5 years, two phase II clinical trials have reported their long term follow up results and many additional biomaterial candidates have reached preclinical and clinical testing. Also in recent years deeper investigations into the mechanisms behind the beneficial effects associated with biomaterial injection therapy have been pursued, and a variety of process and material parameters have been evaluated for their impact on therapeutic outcomes. This review explores the advances made in this biomaterial-centered approach to ischemic cardiomyopathy and discusses potential future research directions as this therapy seeks to positively impact patients suffering from one of the world's most common sources of mortality.
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Affiliation(s)
- Yang Zhu
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, 15219, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, 15219, USA
| | - Yasumoto Matsumura
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, 15219, USA
| | - William R Wagner
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, 15219, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, 15219, USA; Department of Surgery, University of Pittsburgh, Pittsburgh, PA, 15219, USA; Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, PA, 15219, USA.
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