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Wang B, Gao C, Lim S, Wang R, Zhu CJ, Onuma Y, Wang Y, Gao R, Serruys PWJC, Lee RJ, Tao L. Percutaneous Alginate Hydrogel Endomyocardial Injection with a Novel Dedicated Catheter Delivery System: An Animal Feasibility Study. J Cardiovasc Transl Res 2024:10.1007/s12265-024-10497-8. [PMID: 38376702 DOI: 10.1007/s12265-024-10497-8] [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: 10/17/2023] [Accepted: 02/06/2024] [Indexed: 02/21/2024]
Abstract
The objective of this preclinical study was to evaluate the feasibility and safety of transcatheter endocardial alginate hydrogel injection (TEAi) in a large animal model, utilizing the high-stiffness XDROP® alginate hydrogel in combination with the dedicated EndoWings® catheter-based system. All swine (n = 9) successfully underwent TEAi without complications. Acute results from a subset of animals (n = 5) demonstrated the ability of the catheter to access a wide range of endomyocardial areas and achieve consecutive circumferential hydrogel distribution patterns within the mid-left ventricular wall. Histological examinations at 6 months (n = 4) demonstrated that the XDROP® remained localized within the cardiac tissue. In addition, serial echocardiographic imaging showed that XDROP® had no adverse impacts on LV systolic and diastolic functions. In conclusion, this innovative combination technology has the potential to overcome the translational barriers related to alginate hydrogel delivery to the myocardium.
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Affiliation(s)
- Bo Wang
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
- Corrib Research Centre for Advanced Imaging and Core Laboratory, University of Galway, Galway, Ireland
| | - Chao Gao
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Scott Lim
- Department of Medicine, Division of Cardiovascular Medicine, University of Virginia, Charlottesville, VA, USA
| | - Rutao Wang
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Cun-Jun Zhu
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Yoshinobu Onuma
- Corrib Research Centre for Advanced Imaging and Core Laboratory, University of Galway, Galway, Ireland
| | - Yunbing Wang
- National Engineering Research Center for Biomaterials, Sichuan University, Sichuan, China
| | - Runlin Gao
- Fuwai Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Patrick W J C Serruys
- Corrib Research Centre for Advanced Imaging and Core Laboratory, University of Galway, Galway, Ireland.
| | - Randall J Lee
- Department of Medicine, University of California-San Francisco, San Francisco, CA, USA.
| | - Ling Tao
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
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Avendaño R, Midgett D, Melvinsdottir I, Thorn SL, Uman S, Pickell Z, Lee SR, Liu Z, Mamarian M, Duncan JS, Spinale FG, Burdick JA, Sinusas AJ. Improvement in cardiac function and regional LV strain following intramyocardial injection of a theranostic hydrogel early postmyocardial infarction in a porcine model. J Appl Physiol (1985) 2023; 135:405-420. [PMID: 37318987 PMCID: PMC10538987 DOI: 10.1152/japplphysiol.00342.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 05/23/2023] [Accepted: 06/14/2023] [Indexed: 06/17/2023] Open
Abstract
Myocardial infarction (MI) is often complicated by left ventricular (LV) remodeling and heart failure. We evaluated the feasibility of a multimodality imaging approach to guide delivery of an imageable hydrogel and assessed LV functional changes with therapy. Yorkshire pigs underwent surgical occlusions of branches of the left anterior descending and/or circumflex artery to create an anterolateral MI. We evaluated the hemodynamic and mechanical effects of intramyocardial delivery of an imageable hydrogel in the central infarct area (Hydrogel group, n = 8) and a Control group (n = 5) early post-MI. LV and aortic pressure and ECG were measured and contrast cineCT angiography was performed at baseline, 60 min post-MI, and 90 min post-hydrogel delivery. LV hemodynamic indices, pressure-volume measures, and normalized regional and global strains were measured and compared. Both Control and Hydrogel groups demonstrated a decline in heart rate, LV pressure, stroke volume, ejection fraction, and pressure-volume loop area, and an increase in myocardial performance (Tei) index and supply/demand (S/D) ratio. After hydrogel delivery, Tei index and S/D ratio were reduced to baseline levels, diastolic and systolic functional indices either stabilized or improved, and radial strain and circumferential strain increased significantly in the MI regions (ENrr: +52.7%, ENcc: +44.1%). However, the Control group demonstrated a progressive decline in all functional indices to levels significantly below those of Hydrogel group. Thus, acute intramyocardial delivery of a novel imageable hydrogel to MI region resulted in rapid stabilization or improvement in LV hemodynamics and function.NEW & NOTEWORTHY Our study demonstrates that contrast cineCT imaging can be used to evaluate the acute effects of intramyocardial delivery of a therapeutic hydrogel to the central MI region early post MI, which resulted in a rapid stabilization of LV hemodynamics and improvement in regional and global LV function.
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Affiliation(s)
- Ricardo Avendaño
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States
| | - Dan Midgett
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, United States
| | - Inga Melvinsdottir
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States
| | - Stephanie L Thorn
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States
| | - Selen Uman
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Zachary Pickell
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States
| | - Shin Rong Lee
- Department of Surgery, Yale University School of Medicine, New Haven, Connecticut, United States
| | - Zhao Liu
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, United States
| | - Marina Mamarian
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States
| | - James S Duncan
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, United States
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut, United States
| | - Francis G Spinale
- Department of Cell Biology & Anatomy, University of South Carolina School of Medicine, Columbia, South Carolina, United States
| | - Jason A Burdick
- Biofrontiers Institute, University of Colorado Boulder, Boulder, Colorado, United States
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado, United States
| | - Albert J Sinusas
- Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, United States
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut, United States
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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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Midgett D, Thorn S, Ahn S, Uman S, Avendano R, Melvinsdottir I, Lysyy T, Kim S, Duncan J, Humphrey J, Papademetris X, Burdick J, Sinusas A. CineCT platform for in vivo and ex vivo measurement of 3D high resolution Lagrangian strains in the left ventricle following myocardial infarction and intramyocardial delivery of theranostic hydrogel. J Mol Cell Cardiol 2022; 166:74-90. [PMID: 35227737 PMCID: PMC9035115 DOI: 10.1016/j.yjmcc.2022.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 02/10/2022] [Accepted: 02/16/2022] [Indexed: 02/07/2023]
Abstract
Myocardial infarction (MI) produces acute changes in strain and stiffness within the infarct that can affect remote areas of the left ventricle (LV) and drive pathological remodeling. We hypothesized that intramyocardial delivery of a hydrogel within the MI region would lower wall stress and reduce adverse remodeling in Yorkshire pigs (n = 5). 99mTc-Tetrofosmin SPECT imaging defined the location and geometry of induced MI and border regions in pigs, and in vivo and ex vivo contrast cine computed tomography (cineCT) quantified deformations of the LV myocardium. Serial in vivo cineCT imaging provided data in hearts from control pigs (n = 3) and data from pigs (n = 5) under baseline conditions before MI induction, post-MI day 3, post-MI day 7, and one hour after intramyocardial delivery of a hyaluronic acid (HA)-based hydrogel with shear-thinning and self-healing properties to the central infarct area. Isolated, excised hearts underwent similar cineCT imaging using an ex vivo perfused heart preparation with cyclic LV pressurization. Deformations were evaluated using nonlinear image registration of cineCT volumes between end-diastole (ED) and end-systole (ES), and 3D Lagrangian strains were calculated from the displacement gradients. Post-MI day 3, radial, circumferential, maximum principal, and shear strains were reduced within the MI region (p < 0.04) but were unchanged in normal regions (p > 0.6), and LV end diastolic volume (LV EDV) increased (p = 0.004), while ejection fraction (EF) and stroke volume (SV) decreased (p < 0.02). Post-MI day 7, radial strains in MI border zones increased (p = 0.04) and dilation of LV EDV continued (p = 0.052). There was a significant negative linear correlation between regional radial and maximum principal/shear strains and percent infarcted tissue in all hearts (R2 > 0.47, p < 0.004), indicating that cineCT strain measures could predict MI location and degree of injury. Post-hydrogel day 7 post-MI, LV EDV was significantly reduced (p = 0.009), EF increased (p = 0.048), and radial (p = 0.021), maximum principal (p = 0.051), and shear strain (p = 0.047) increased within regions bordering the infarct. A smaller strain improvement within the infarct and normal regions was also noted on average along with an improvement in SV in 4 out of 5 hearts. CineCT provides a reliable method to assess regional changes in strains post-MI and the therapeutic effects of intramyocardial hydrogel delivery.
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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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6
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Sack KL, Aliotta E, Choy JS, Ennis DB, Davies NH, Franz T, Kassab GS, Guccione JM. Intra-myocardial alginate hydrogel injection acts as a left ventricular mid-wall constraint in swine. Acta Biomater 2020; 111:170-180. [PMID: 32428678 PMCID: PMC7368390 DOI: 10.1016/j.actbio.2020.04.033] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 04/09/2020] [Accepted: 04/20/2020] [Indexed: 02/07/2023]
Abstract
Despite positive initial outcomes emerging from preclinical and early clinical investigation of alginate hydrogel injection therapy as a treatment for heart failure, the lack of knowledge about the mechanism of action remains a major shortcoming that limits the efficacy of treatment design. To identify the mechanism of action, we examined previously unobtainable measurements of cardiac function from in vivo, ex vivo, and in silico states of clinically relevant heart failure (HF) in large animals. High-resolution ex vivo magnetic resonance imaging and histological data were used along with state-of-the-art subject-specific computational model simulations. Ex vivo data were incorporated in detailed geometric computational models for swine hearts in health (n = 5), ischemic HF (n = 5), and ischemic HF treated with alginate hydrogel injection therapy (n = 5). Hydrogel injection therapy mitigated elongation of sarcomere lengths (1.68 ± 0.10μm [treated] vs. 1.78 ± 0.15μm [untreated], p<0.001). Systolic contractility in treated animals improved substantially (ejection fraction = 43.9 ± 2.8% [treated] vs. 34.7 ± 2.7% [untreated], p<0.01). The in silico models realistically simulated in vivo function with >99% accuracy and predicted small myofiber strain in the vicinity of the solidified hydrogel that was sustained for up to 13 mm away from the implant. These findings suggest that the solidified alginate hydrogel material acts as an LV mid-wall constraint that significantly reduces adverse LV remodeling compared to untreated HF controls without causing negative secondary outcomes to cardiac function. STATEMENT OF SIGNIFICANCE: Heart failure is considered a growing epidemic and hence an important health problem in the US and worldwide. Its high prevalence (5.8 million and 23 million, respectively) is expected to increase by 25% in the US alone by 2030. Heart failure is associated with high morbidity and mortality, has a 5-year mortality rate of 50%, and contributes considerably to the overall cost of health care ($53.1 billion in the US by 2030). Despite positive initial outcomes emerging from preclinical and early clinical investigation of alginate hydrogel injection therapy as a treatment for heart failure, the lack of knowledge concerning the mechanism of action remains a major shortcoming that limits the efficacy of treatment design. To understand the mechanism of action, we combined high-resolution ex vivo magnetic resonance imaging and histological data in swine with state-of-the-art subject-specific computational model simulations. The in silico models realistically simulated in vivo function with >99% accuracy and predicted small myofiber strain in the vicinity of the solidified hydrogel that was sustained for up to 13 mm away from the implant. These findings suggest that the solidified alginate hydrogel material acts as a left ventricular mid-wall constraint that significantly reduces adverse LV remodeling compared to untreated heart failure controls without causing negative secondary outcomes to cardiac function. Moreover, if the hydrogel can be delivered percutaneously rather than via the currently used open-chest procedure, this therapy may become routine for heart failure treatment. A minimally invasive procedure would be in the best interest of this patient population; i.e., one that cannot tolerate general anesthesia and surgery, and it would be significantly more cost-effective than surgery.
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Affiliation(s)
- Kevin L Sack
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California at San Francisco, Box 0118, UC Hall Room U-158, San Francisco, CA, United States; Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Cape Town, South Africa
| | - Eric Aliotta
- Department of Radiological Sciences, University of California, Los Angeles, California, USA
| | - Jenny S Choy
- California Medical Innovations Institute, Inc., San Diego, California, USA
| | - Daniel B Ennis
- Department of Radiological Sciences, University of California, Los Angeles, California, USA
| | - Neil H Davies
- Cardiovascular Research Unit, Department of Surgery, University of Cape Town, Cape Town, South Africa
| | - Thomas Franz
- Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Cape Town, South Africa; Bioengineering Science Research Group, Engineering Sciences, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
| | - Ghassan S Kassab
- California Medical Innovations Institute, Inc., San Diego, California, USA
| | - Julius M Guccione
- Division of Adult Cardiothoracic Surgery, Department of Surgery, University of California at San Francisco, Box 0118, UC Hall Room U-158, San Francisco, CA, United States.
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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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Sack KL, Davies NH, Guccione JM, Franz T. Personalised computational cardiology: Patient-specific modelling in cardiac mechanics and biomaterial injection therapies for myocardial infarction. Heart Fail Rev 2018; 21:815-826. [PMID: 26833320 PMCID: PMC4969231 DOI: 10.1007/s10741-016-9528-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Predictive computational modelling in biomedical research offers the potential to integrate diverse data, uncover biological mechanisms that are not easily accessible through experimental methods and expose gaps in knowledge requiring further research. Recent developments in computing and diagnostic technologies have initiated the advancement of computational models in terms of complexity and specificity. Consequently, computational modelling can increasingly be utilised as enabling and complementing modality in the clinic—with medical decisions and interventions being personalised. Myocardial infarction and heart failure are amongst the leading causes of death globally despite optimal modern treatment. The development of novel MI therapies is challenging and may be greatly facilitated through predictive modelling. Here, we review the advances in patient-specific modelling of cardiac mechanics, distinguishing specificity in cardiac geometry, myofibre architecture and mechanical tissue properties. Thereafter, the focus narrows to the mechanics of the infarcted heart and treatment of myocardial infarction with particular attention on intramyocardial biomaterial delivery.
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Affiliation(s)
- Kevin L Sack
- Division of Biomedical Engineering, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Private Bag X3, 7935, Observatory, South Africa
| | - Neil H Davies
- Cardiovascular Research Unit, MRC IUCHRU, Chris Barnard Division of Cardiothoracic Surgery, University of Cape Town, Observatory, South Africa
| | - Julius M Guccione
- Department of Surgery, University of California at San Francisco, San Francisco, CA, USA
| | - Thomas Franz
- Division of Biomedical Engineering, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Private Bag X3, 7935, Observatory, South Africa.
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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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