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Vernon MJ, Mela P, Dilley RJ, Jansen S, Doyle BJ, Ihdayhid AR, De-Juan-Pardo EM. 3D printing of heart valves. Trends Biotechnol 2024; 42:612-630. [PMID: 38238246 DOI: 10.1016/j.tibtech.2023.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/31/2023] [Accepted: 11/01/2023] [Indexed: 05/04/2024]
Abstract
3D printing technologies have the potential to revolutionize the manufacture of heart valves through the ability to create bespoke, complex constructs. In light of recent technological advances, we review the progress made towards 3D printing of heart valves, focusing on studies that have utilised these technologies beyond manufacturing patient-specific moulds. We first overview the key requirements of a heart valve to assess functionality. We then present the 3D printing technologies used to engineer heart valves. By referencing International Organisation for Standardisation (ISO) Standard 5840 (Cardiovascular implants - Cardiac valve prostheses), we provide insight into the achieved functionality of these valves. Overall, 3D printing promises to have a significant positive impact on the creation of artificial heart valves and potentially unlock full complex functionality.
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Affiliation(s)
- Michael J Vernon
- T3mPLATE, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre and University of Western Australia Centre for Medical Research, The University of Western Australia, Perth, WA 6009, Australia; Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre and University of Western Australia Centre for Medical Research, The University of Western Australia, Perth, WA 6009, Australia; School of Engineering, The University of Western Australia, Perth, WA 6009, Australia
| | - Petra Mela
- Medical Materials and Implants, Department of Mechanical Engineering, Munich Institute of Biomedical Engineering and TUM School of Engineering and Design, Technical University of Munich, Boltzmannstrasse 15, 85748 Garching, Germany
| | - Rodney J Dilley
- T3mPLATE, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre and University of Western Australia Centre for Medical Research, The University of Western Australia, Perth, WA 6009, Australia
| | - Shirley Jansen
- Curtin Medical School, Curtin University, Perth, WA 6102, Australia; School of Medicine, Faculty of Health and Medical Sciences, The University of Western Australia, Perth, WA 6009, Australia; Department of Vascular and Endovascular Surgery, Sir Charles Gairdner Hospital, Perth, WA 6009, Australia; Heart and Vascular Research Institute, Harry Perkins Institute of Medical Research, Perth, WA 6009, Australia
| | - Barry J Doyle
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre and University of Western Australia Centre for Medical Research, The University of Western Australia, Perth, WA 6009, Australia; School of Engineering, The University of Western Australia, Perth, WA 6009, Australia
| | - Abdul R Ihdayhid
- T3mPLATE, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre and University of Western Australia Centre for Medical Research, The University of Western Australia, Perth, WA 6009, Australia; Curtin Medical School, Curtin University, Perth, WA 6102, Australia; Department of Cardiology, Fiona Stanley Hospital, Perth, WA 6150, Australia
| | - Elena M De-Juan-Pardo
- T3mPLATE, Harry Perkins Institute of Medical Research, Queen Elizabeth II Medical Centre and University of Western Australia Centre for Medical Research, The University of Western Australia, Perth, WA 6009, Australia; School of Engineering, The University of Western Australia, Perth, WA 6009, Australia; Curtin Medical School, Curtin University, Perth, WA 6102, Australia.
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2
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De Jesus Morales KJ, Santosa U, Brazhkina O, Rajurkar P, Jo H, Davis ME. A Biomimetic Leaflet Scaffold for Aortic Valve Remodeling. Adv Healthc Mater 2024:e2303972. [PMID: 38692263 DOI: 10.1002/adhm.202303972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 03/28/2024] [Indexed: 05/03/2024]
Abstract
Heart valve disease poses a significant clinical challenge, especially in pediatric populations, due to the inability of existing valve replacements to grow or respond biologically to their microenvironment. Tissue-engineered heart valves (TEHVs) provide a solution by facilitating patient-specific models for self-repair and remodeling. In this study, a 3D-bioprinted TEHV is designed to emulate the trilayer leaflet structure of an aortic valve. A cell-laden hydrogel scaffold made from gelatin methacrylate and polyethylene glycol diacrylate (GelMA/PEGDA) incorporates valvular interstitial-like (VIC-like) cells, being reinforced with a layer of polycaprolactone (PCL). The composition of the hydrogel scaffold remains stable over 7 days, having increased mechanical strength compared to pure GelMA. The scaffold maintains VIC-like cell function and promotes extracellular matrix (ECM) protein expression up to 14 days under two dynamic culture conditions: shear stress and stretching; replicating heart valve behavior within a more physiological-like setting and suggesting remodeling potential via ECM synthesis. This TEHV offers a promising avenue for valve replacements, closely replicating the structural and functional attributes of a native aortic valve, leading to mechanical and biological integration through biomaterial-cellular interactions.
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Affiliation(s)
- Kenneth J De Jesus Morales
- Wallace H. Coulter Department of Biomedical Engineering, Emory University School of Medicine & Georgia Institute of Technology, Atlanta, GA, 30322, USA
| | - Utari Santosa
- Wallace H. Coulter Department of Biomedical Engineering, Emory University School of Medicine & Georgia Institute of Technology, Atlanta, GA, 30322, USA
| | - Olga Brazhkina
- Wallace H. Coulter Department of Biomedical Engineering, Emory University School of Medicine & Georgia Institute of Technology, Atlanta, GA, 30322, USA
| | - Pranshu Rajurkar
- Wallace H. Coulter Department of Biomedical Engineering, Emory University School of Medicine & Georgia Institute of Technology, Atlanta, GA, 30322, USA
| | - Hanjoong Jo
- Wallace H. Coulter Department of Biomedical Engineering, Emory University School of Medicine & Georgia Institute of Technology, Atlanta, GA, 30322, USA
- Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Michael E Davis
- Wallace H. Coulter Department of Biomedical Engineering, Emory University School of Medicine & Georgia Institute of Technology, Atlanta, GA, 30322, USA
- Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA, 30322, USA
- Children's Heart Research & Outcomes (HeRO) Center, Children's Healthcare of Atlanta & Emory University, Atlanta, GA, 30322, USA
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3
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Zhu Z, Liu Z, Zhang D, Li L, Pei J, Cai L. Models for calcific aortic valve disease in vivo and in vitro. CELL REGENERATION (LONDON, ENGLAND) 2024; 13:6. [PMID: 38424219 PMCID: PMC10904700 DOI: 10.1186/s13619-024-00189-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 02/06/2024] [Indexed: 03/02/2024]
Abstract
Calcific Aortic Valve Disease (CAVD) is prevalent among the elderly as the most common valvular heart disease. Currently, no pharmaceutical interventions can effectively reverse or prevent CAVD, making valve replacement the primary therapeutic recourse. Extensive research spanning decades has contributed to the establishment of animal and in vitro cell models, which facilitates a deeper understanding of the pathophysiological progression and underlying mechanisms of CAVD. In this review, we provide a comprehensive summary and analysis of the strengths and limitations associated with commonly employed models for the study of valve calcification. We specifically emphasize the advancements in three-dimensional culture technologies, which replicate the structural complexity of the valve. Furthermore, we delve into prospective recommendations for advancing in vivo and in vitro model studies of CAVD.
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Affiliation(s)
- Zijin Zhu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, National & Local Joint Engineering Research Center of High-Throughput Drug Screening Technology, Hubei University, Wuhan, 430062, China
| | - Zhirong Liu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, National & Local Joint Engineering Research Center of High-Throughput Drug Screening Technology, Hubei University, Wuhan, 430062, China
| | - Donghui Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, National & Local Joint Engineering Research Center of High-Throughput Drug Screening Technology, Hubei University, Wuhan, 430062, China
| | - Li Li
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, National & Local Joint Engineering Research Center of High-Throughput Drug Screening Technology, Hubei University, Wuhan, 430062, China.
| | - Jianqiu Pei
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Beijing Key Laboratory of Metabolic Disorders Related Cardiovascular Disease, Capital Medical University, Beijing, 100069, China.
| | - Lin Cai
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Science, National & Local Joint Engineering Research Center of High-Throughput Drug Screening Technology, Hubei University, Wuhan, 430062, China.
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4
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West TM, Howsmon DP, Massidda MW, Vo HN, Janobas AA, Baker AB, Sacks MS. The effects of strain history on aortic valve interstitial cell activation in a 3D hydrogel environment. APL Bioeng 2023; 7:026101. [PMID: 37035541 PMCID: PMC10076067 DOI: 10.1063/5.0138030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 03/13/2023] [Indexed: 04/05/2023] Open
Abstract
Aortic valves (AVs) undergo unique stretch histories that include high rates and magnitudes. While major differences in deformation patterns have been observed between normal and congenitally defective bicuspid aortic valves (BAVs), the relation to underlying mechanisms of rapid disease onset in BAV patients remains unknown. To evaluate how the variations in stretch history affect AV interstitial cell (AVIC) activation, high-throughput methods were developed to impart varied cyclical biaxial stretch histories into 3D poly(ethylene) glycol hydrogels seeded with AVICs for 48 h. Specifically, a physiologically mimicking stretch history was compared to two stretch histories with varied peak stretch and stretch rate. Post-conditioned AVICs were imaged for nuclear shape, alpha smooth muscle actin (αSMA) and vimentin (VMN) polymerization, and small mothers against decapentaplegic homologs 2 and 3 (SMAD 2/3) nuclear activity. The results indicated that bulk gel deformations were accurately transduced to the AVICs. Lower peak stretches lead to increased αSMA polymerization. In contrast, VMN polymerization was a function of stretch rate, with SMAD 2/3 nuclear localization and nuclear shape also trending toward stretch rate dependency. Lower than physiological levels of stretch rate led to higher SMAD 2/3 activity, higher VMN polymerization around the nucleus, and lower nuclear elongation. αSMA polymerization did not correlate with VMN polymerization, SMAD 2/3 activity, nor nuclear shape. These results suggest that a negative feedback loop may form between SMAD 2/3, VMN, and nuclear shape to maintain AVIC homeostatic nuclear deformations, which is dependent on stretch rate. These novel results suggest that AVIC mechanobiological responses are sensitive to stretch history and provide insight into the mechanisms of AV disease.
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Affiliation(s)
- Toni M. West
- James T. Willerson Center for Cardiovascular Modelling and Simulation, Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, Austin, Texas 78711, USA
| | - Daniel P. Howsmon
- James T. Willerson Center for Cardiovascular Modelling and Simulation, Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, Austin, Texas 78711, USA
| | - Miles W. Massidda
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78711, USA
| | | | | | - Aaron B. Baker
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78711, USA
| | - Michael S. Sacks
- James T. Willerson Center for Cardiovascular Modelling and Simulation, Oden Institute for Computational Engineering and Sciences and the Department of Biomedical Engineering, Austin, Texas 78711, USA
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5
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Calcific aortic valve disease: mechanisms, prevention and treatment. Nat Rev Cardiol 2023:10.1038/s41569-023-00845-7. [PMID: 36829083 DOI: 10.1038/s41569-023-00845-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/01/2023] [Indexed: 02/26/2023]
Abstract
Calcific aortic valve disease (CAVD) is the most common disorder affecting heart valves and is characterized by thickening, fibrosis and mineralization of the aortic valve leaflets. Analyses of surgically explanted aortic valve leaflets have shown that dystrophic mineralization and osteogenic transition of valve interstitial cells co-occur with neovascularization, microhaemorrhage and abnormal production of extracellular matrix. Age and congenital bicuspid aortic valve morphology are important and unalterable risk factors for CAVD, whereas additional risk is conferred by elevated blood pressure and plasma lipoprotein(a) levels and the presence of obesity and diabetes mellitus, which are modifiable factors. Genetic and molecular studies have identified that the NOTCH, WNT-β-catenin and myocardin signalling pathways are involved in the control and commitment of valvular cells to a fibrocalcific lineage. Complex interactions between valve endothelial and interstitial cells and immune cells promote the remodelling of aortic valve leaflets and the development of CAVD. Although no medical therapy is effective for reducing or preventing the progression of CAVD, studies have started to identify actionable targets.
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Vernon MJ, Lu J, Padman B, Lamb C, Kent R, Mela P, Doyle B, Ihdayhid AR, Jansen S, Dilley RJ, De-Juan-Pardo EM. Engineering Heart Valve Interfaces Using Melt Electrowriting: Biomimetic Design Strategies from Multi-Modal Imaging. Adv Healthc Mater 2022; 11:e2201028. [PMID: 36300603 DOI: 10.1002/adhm.202201028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 09/12/2022] [Indexed: 01/28/2023]
Abstract
Interfaces within biological tissues not only connect different regions but also contribute to the overall functionality of the tissue. This is especially true in the case of the aortic heart valve. Here, melt electrowriting (MEW) is used to engineer complex, user-defined, interfaces for heart valve scaffolds. First, a multi-modal imaging investigation into the interfacial regions of the valve reveals differences in collagen orientation, density, and recruitment in previously unexplored regions including the commissure and inter-leaflet triangle. Overlapping, suturing, and continuous printing methods for interfacing MEW scaffolds are then investigated for their morphological, tensile, and flexural properties, demonstrating the superior performance of continuous interfaces. G-codes for MEW scaffolds with complex interfaces are designed and generated using a novel software and graphical user interface. Finally, a singular MEW scaffold for the interfacial region of the aortic heart valve is presented incorporating continuous interfaces, gradient porosities, variable layer numbers across regions, and tailored fiber orientations inspired by the collagen distribution and orientation from the multi-modal imaging study. The scaffold exhibits similar yield strain, hysteresis, and relaxation behavior to porcine heart valves. This work demonstrates the ability of a bioinspired approach for MEW scaffold design to address the functional complexity of biological tissues.
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Affiliation(s)
- Michael J Vernon
- T3mPLATE, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,School of Engineering, The University of Western Australia, Perth, WA, 6009, Australia
| | - Jason Lu
- T3mPLATE, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,School of Engineering, The University of Western Australia, Perth, WA, 6009, Australia
| | - Benjamin Padman
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, WA, 6009, Australia
| | - Christopher Lamb
- T3mPLATE, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,School of Engineering, The University of Western Australia, Perth, WA, 6009, Australia
| | - Ross Kent
- Regenerative Medicine Program, CIMA, Universidad de Navarra, Pamplona, Navarra, 31008, Spain
| | - Petra Mela
- Medical Materials and Implants, Department of Mechanical Engineering, Munich Institute of Biomedical Engineering and TUM School of Engineering and Design, Technical University of Munich, Boltzmannstr. 15, 85748, Garching, Germany
| | - Barry Doyle
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,School of Engineering, The University of Western Australia, Perth, WA, 6009, Australia.,Australian Research Council Centre for Personalised Therapeutics Technologies, Australian Research Council, Parkville, ACT, 2609, Australia.,British Heart Foundation Centre of Cardiovascular Science, The University of Edinburgh, Edinburgh, EH1-3AT, UK
| | - Abdul Rahman Ihdayhid
- Department of Cardiology, Fiona Stanley Hospital, Perth, WA, 6150, Australia.,Curtin Medical School, Curtin University, Perth, WA, 6102, Australia
| | - Shirley Jansen
- Vascular Engineering Laboratory, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,Curtin Medical School, Curtin University, Perth, WA, 6102, Australia.,Department of Vascular and Endovascular Surgery, Sir Charles Gairdner Hospital, Perth, WA, 6009, Australia.,Heart and Vascular Research Institute, Harry Perkins Institute of Medical Research, Perth, WA, 6009, Australia
| | - Rodney J Dilley
- T3mPLATE, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,School of Engineering, The University of Western Australia, Perth, WA, 6009, Australia
| | - Elena M De-Juan-Pardo
- T3mPLATE, Harry Perkins Institute of Medical Research, QEII Medical Centre, and UWA Centre for Medical Research, The University of Western Australia, Perth, WA, 6009, Australia.,School of Engineering, The University of Western Australia, Perth, WA, 6009, Australia
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7
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Benchtop characterization of the tricuspid valve leaflet pre-strains. Acta Biomater 2022; 152:321-334. [PMID: 36041649 DOI: 10.1016/j.actbio.2022.08.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 08/01/2022] [Accepted: 08/22/2022] [Indexed: 11/21/2022]
Abstract
The pre-strains of biological soft tissues are important when relating their in vitro and in vivo mechanical behaviors. In this study, we present the first-of-its-kind experimental characterization of the tricuspid valve leaflet pre-strains. We use 3D photogrammetry and the reproducing kernel method to calculate the pre-strains within the central 10×10 mm region of the tricuspid valve leaflets from n=8 porcine hearts. In agreement with previous pre-strain studies for heart valve leaflets, our results show that all the three tricuspid valve leaflets shrink after explant from the ex vivo heart. These calculated strains are leaflet-specific and the septal leaflet experiences the most compressive changes. Furthermore, the strains observed after dissection of the central 10×10 mm region of the leaflet are smaller than when the valve is explanted, suggesting that our computed pre-strains are mainly due to the release of in situ annulus and chordae connections. The leaflets are then mounted on a biaxial testing device and preconditioned using force-controlled equibiaxial loading. We show that the employed preconditioning protocol does not 100% restore the leaflet pre-strains as removed during tissue dissection, and future studies are warranted to explore alternative preconditioning methods. Finally, we compare the calculated biomechanically oriented metrics considering five stress-free reference configurations. Interestingly, the radial tissue stretches and material anisotropies are significantly smaller compared to the post-preconditioning configuration. Extensions of this work can further explore the role of this unique leaflet-specific leaflet pre-strains on in vivo valve behavior via high-fidelity in-silico models.
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8
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Bouten CVC, Cheng C, Vermue IM, Gawlitta D, Passier R. Cardiovascular tissue engineering and regeneration: A plead for further knowledge convergence. Tissue Eng Part A 2022; 28:525-541. [PMID: 35382591 DOI: 10.1089/ten.tea.2021.0231] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cardiovascular tissue engineering and regeneration strive to provide long-term, effective solutions for a growing group of patients in need of myocardial repair, vascular (access) grafts, heart valves, and regeneration of organ microcirculation. In the past two decades, ongoing convergence of disciplines and multidisciplinary collaborations between cardiothoracic surgeons, cardiologists, bioengineers, material scientists, and cell biologists have resulted in better understanding of the problems at hand and novel regenerative approaches. As a side effect, however, the field has become strongly organized and differentiated around topical areas at risk of reinvention of technologies and repetition of approaches and across the areas. A better integration of knowledge and technologies from the individual topical areas and regenerative approaches and technologies may pave the way towards faster and more effective treatments to cure the cardiovascular system. This review summarizes the evolution of research and regenerative approaches in the areas of myocardial regeneration, heart valve and vascular tissue engineering, and regeneration of microcirculations and discusses previous and potential future integration of these individual areas and developed technologies for improved clinical impact. Finally, it provides a perspective on the further integration of research organization, knowledge implementation, and valorization as a contributor to advancing cardiovascular tissue engineering and regenerative medicine.
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Affiliation(s)
- Carlijn V C Bouten
- Soft Tissue Engineering and Mechanobiology, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
- Institute for Complex Molecular Systems (ICMS), Eindhoven, The Netherlands
| | - Caroline Cheng
- Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands
- Experimental Cardiology, Department of Cardiology, Thoraxcenter Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Ijsbrand M Vermue
- Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Debby Gawlitta
- Department of Oral and Maxillofacial Surgery, Prosthodontics and Special Dental Care, University Medical Center, Utrecht, The Netherlands
| | - Robert Passier
- Department of Applied Stem Cell Technologies, Faculty of Science and Technology, University of Twente, Enschede, The Netherlands
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, The Netherlands
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9
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Biomechanics of mitral valve leaflets: Second harmonic generation microscopy, biaxial mechanical tests and tissue modeling. Acta Biomater 2022; 141:244-254. [PMID: 35007783 DOI: 10.1016/j.actbio.2022.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 12/10/2021] [Accepted: 01/03/2022] [Indexed: 12/30/2022]
Abstract
Collagen fibers are the main load carrier in the mitral valve (MV) leaflets. Their orientation and dispersion are an important factor for the mechanical behavior. Most recent studies of collagen fibers in MVs lack either entire thickness study or high transmural resolution. The present study uses second harmonic generation (SHG) microscopy in combination with planar biaxial mechanical tests to better model and examine collagen fibers and mechanical properties of MV leaflets. SHG in combination with tissue clearing enables the collagen fibers to be examined through the entire thickness of the MV leaflets. Planar biaxial mechanical tests, on the other hand, enable the characterization of the mechanical tissue behavior, which is represented by a structural tissue model. Twelve porcine MV leaflets are examined. The SHG recording shows that the mean fiber angle for all samples varies on average by ±12° over the entire thickness and the collagen fiber dispersion changes strongly over the thickness. A constitutive model based on the generalized structure tensor approach is used for the associated tissue characterization. The model represents the tissue with three mechanical parameters plus the mean fiber direction and the dispersion, and predicts the biomechanical response of the leaflets with a good agreement (average r2=0.94). It is found that the collagen structure can be represented by a mean direction and a dispersion with a single family of fibers despite the variation in the collagen fiber direction and the dispersion over the entire thickness of MV leaflets. STATEMENT OF SIGNIFICANCE: Despite its prominent role in the mechanical behavior of mitral valve (MV) leaflets, the collagen structure has not yet been investigated over the entire thickness with high transmural resolution. The present study quantifies the detailed through thickness collagen fiber structure and examines the effects of its variation on MV tissue modeling. This is important because the study evaluates the assumption that the collagen fibers can be modeled with a representative single fiber family despite the variation across the thickness. In addition, the current comprehensive data set paves the way for quantifying the disruption of collagen fibers in myxomatous MV leaflets associated with disrupted collagen fibers.
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10
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Liang X, Zheng C, Ding K, Huang X, Zhang S, Lei Y, Yu K, Wang Y. Arginine-grafted porcine pericardium by copolymerization to improve cytocompatibility, hemocompatibility and anti-calcification properties of bioprosthetic heart valve materials. J Mater Chem B 2022; 10:5571-5581. [DOI: 10.1039/d2tb00798c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bioprosthetic heart valves (BHVs) have been used widely due to the development of transcatheter heart valve replacement technology. However, glutaraldehyde crosslinked pericardium (GA), which is widely used as a leaflet...
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11
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Ross CJ, Laurence DW, Echols AL, Babu AR, Gu T, Duginski GA, Johns CH, Mullins BT, Casey KM, Laurence KA, Zhao YD, Amini R, Fung KM, Mir A, Burkhart HM, Wu Y, Holzapfel GA, Lee CH. Effects of enzyme-based removal of collagen and elastin constituents on the biaxial mechanical responses of porcine atrioventricular heart valve anterior leaflets. Acta Biomater 2021; 135:425-440. [PMID: 34481053 DOI: 10.1016/j.actbio.2021.08.043] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 08/22/2021] [Accepted: 08/26/2021] [Indexed: 12/24/2022]
Abstract
The leaflets of the atrioventricular heart valves (AHVs) regulate the one-directional flow of blood through a coordination of the extracellular matrix components, including the collagen fibers, elastin, and glycosaminoglycans. Dysfunction of the AHVs, such as those caused by unfavorable microstructural remodeling, lead to valvular heart diseases and improper blood flow, which can ultimately cause heart failure. In order to better understand the mechanics and remodeling of the AHV leaflets and how therapeutics can inadvertently cause adverse microstructural changes, a systematic characterization of the role of each constituent in the biomechanical properties is appropriate. Previous studies have quantified the contributions of the individual microstructural components to tissue-level behavior for the semilunar valve cusps, but not for the AHV leaflets. In this study, for the first time, we quantify the relationships between microstructure and mechanics of the AHV leaflet using a three-step experimental procedure: (i) biaxial tension and stress relaxation testing of control (untreated) porcine AHV anterior leaflet specimens; (ii) enzyme treatment to remove a portion of either the collagen or elastin constituent; and (iii) biaxial tensile and stress relaxation testing of the constituent-removed (treated) specimens. We have observed that the removal of ∼100% elastin resulted in a ∼10% decrease in the tissue extensibility with biaxial tension and a ∼10% increase in the overall stress reduction with stress relaxation. In contrast, removal of 46% of the collagen content insignificantly affected tissue extensibility with biaxial tension and significantly increased stress decay (10%) with stress relaxation. These findings provide an insight into the microstructure-mechanics relationship of the AHVs and will be beneficial for future developments and refinements of microstructurally informed constitutive models for the simulation of diseased and surgically intervened AHV function. STATEMENT OF SIGNIFICANCE: This study presents, for the first time, a thorough mechanical characterization of the atrioventricular heart valve leaflets before and after enzymatic removal of elastin and collagen. We found that the biaxial tensile properties of elastin-deficient tissues and collagen-deficient are stiffer. The fact of elastin supporting low-stress valve function and collagen as the main load-bearing component was evident in a decrease in the low-tension modulus for elastin-deficient tissues and in the high-tension modulus for collagen-deficient tissues. Our quantification and experimental technique could be useful in predicting the disease-related changes in heart valve mechanics. The information obtained from this work is valuable for refining the constitutive models that describe the essential microstructure-mechanics relationship.
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12
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Deb N, Lacerda CMR. Valvular Endothelial Cell Response to the Mechanical Environment-A Review. Cell Biochem Biophys 2021; 79:695-709. [PMID: 34661855 DOI: 10.1007/s12013-021-01039-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 10/02/2021] [Indexed: 01/08/2023]
Abstract
Heart valve leaflets are complex structures containing valve endothelial cells, interstitial cells, and extracellular matrix. Heart valve endothelial cells sense mechanical stimuli, and communicate amongst themselves and the surrounding cells and extracellular matrix to maintain tissue homeostasis. In the presence of abnormal mechanical stimuli, endothelial cell communication is triggered in defense and such processes may eventually lead to cardiac disease progression. This review focuses on the role of mechanical stimuli on heart valve endothelial surfaces-from heart valve development and maintenance of tissue integrity to disease progression with related signal pathways involved in this process.
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Affiliation(s)
- Nandini Deb
- Jasper Department of Chemical Engineering, The University of Texas at Tyler, 3900 University Blvd, Tyler, 75799, TX, US
| | - Carla M R Lacerda
- Jasper Department of Chemical Engineering, The University of Texas at Tyler, 3900 University Blvd, Tyler, 75799, TX, US.
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13
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Karakaya C, van Asten JGM, Ristori T, Sahlgren CM, Loerakker S. Mechano-regulated cell-cell signaling in the context of cardiovascular tissue engineering. Biomech Model Mechanobiol 2021; 21:5-54. [PMID: 34613528 PMCID: PMC8807458 DOI: 10.1007/s10237-021-01521-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 09/15/2021] [Indexed: 01/18/2023]
Abstract
Cardiovascular tissue engineering (CVTE) aims to create living tissues, with the ability to grow and remodel, as replacements for diseased blood vessels and heart valves. Despite promising results, the (long-term) functionality of these engineered tissues still needs improvement to reach broad clinical application. The functionality of native tissues is ensured by their specific mechanical properties directly arising from tissue organization. We therefore hypothesize that establishing a native-like tissue organization is vital to overcome the limitations of current CVTE approaches. To achieve this aim, a better understanding of the growth and remodeling (G&R) mechanisms of cardiovascular tissues is necessary. Cells are the main mediators of tissue G&R, and their behavior is strongly influenced by both mechanical stimuli and cell-cell signaling. An increasing number of signaling pathways has also been identified as mechanosensitive. As such, they may have a key underlying role in regulating the G&R of tissues in response to mechanical stimuli. A more detailed understanding of mechano-regulated cell-cell signaling may thus be crucial to advance CVTE, as it could inspire new methods to control tissue G&R and improve the organization and functionality of engineered tissues, thereby accelerating clinical translation. In this review, we discuss the organization and biomechanics of native cardiovascular tissues; recent CVTE studies emphasizing the obtained engineered tissue organization; and the interplay between mechanical stimuli, cell behavior, and cell-cell signaling. In addition, we review past contributions of computational models in understanding and predicting mechano-regulated tissue G&R and cell-cell signaling to highlight their potential role in future CVTE strategies.
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Affiliation(s)
- Cansu Karakaya
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands.,Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Jordy G M van Asten
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands.,Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Tommaso Ristori
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands.,Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands.,Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Cecilia M Sahlgren
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands.,Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands.,Faculty of Science and Engineering, Biosciences, Åbo Akademi, Turku, Finland
| | - Sandra Loerakker
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands. .,Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands.
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14
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Shao Z, Tao T, Xu H, Chen C, Lee I, Chung S, Dong Z, Li W, Ma L, Bai H, Chen Q. Recent progress in biomaterials for heart valve replacement: Structure, function, and biomimetic design. VIEW 2021. [DOI: 10.1002/viw.20200142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Ziyu Shao
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine & Clinical Research Center for Oral Diseases of Zhejiang Province Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University Hangzhou 310006 China
- State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University Hangzhou China
| | - Tingting Tao
- Department of Cardiovascular Surgery The First Affiliated Hospital Zhejiang University School of Medicine Hangzhou Zhejiang Province China
| | - Hongfei Xu
- Department of Cardiovascular Surgery The First Affiliated Hospital Zhejiang University School of Medicine Hangzhou Zhejiang Province China
| | - Cen Chen
- College of Life Sciences and Medicine Zhejiang Sci‐Tech University Hangzhou China
| | - In‐Seop Lee
- College of Life Sciences and Medicine Zhejiang Sci‐Tech University Hangzhou China
- Institute of Natural Sciences Yonsei University Seoul Republic of Korea
| | - Sungmin Chung
- Biomaterials R&D Center GENOSS Co., Ltd. Suwon‐si Republic of Korea
| | - Zhihui Dong
- State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University Hangzhou China
| | - Weidong Li
- Department of Cardiovascular Surgery The First Affiliated Hospital Zhejiang University School of Medicine Hangzhou Zhejiang Province China
| | - Liang Ma
- Department of Cardiovascular Surgery The First Affiliated Hospital Zhejiang University School of Medicine Hangzhou Zhejiang Province China
| | - Hao Bai
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine & Clinical Research Center for Oral Diseases of Zhejiang Province Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University Hangzhou 310006 China
- State Key Laboratory of Chemical Engineering College of Chemical and Biological Engineering Zhejiang University Hangzhou China
| | - Qianming Chen
- Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine & Clinical Research Center for Oral Diseases of Zhejiang Province Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University Hangzhou 310006 China
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15
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Driscoll K, Cruz AD, Butcher JT. Inflammatory and Biomechanical Drivers of Endothelial-Interstitial Interactions in Calcific Aortic Valve Disease. Circ Res 2021; 128:1344-1370. [PMID: 33914601 DOI: 10.1161/circresaha.121.318011] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Calcific aortic valve disease is dramatically increasing in global burden, yet no therapy exists outside of prosthetic replacement. The increasing proportion of younger and more active patients mandates alternative therapies. Studies suggest a window of opportunity for biologically based diagnostics and therapeutics to alleviate or delay calcific aortic valve disease progression. Advancement, however, has been hampered by limited understanding of the complex mechanisms driving calcific aortic valve disease initiation and progression towards clinically relevant interventions.
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Affiliation(s)
| | - Alexander D Cruz
- Meinig School of Biomedical Engineering, Cornell University, Ithaca NY
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16
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Wu B, Zheng C, Ding K, Huang X, Li M, Zhang S, Lei Y, Guo Y, Wang Y. Cross-Linking Porcine Pericardium by 3,4-Dihydroxybenzaldehyde: A Novel Method to Improve the Biocompatibility of Bioprosthetic Valve. Biomacromolecules 2020; 22:823-836. [PMID: 33375781 DOI: 10.1021/acs.biomac.0c01554] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Heart valve replacement is an effective therapy for patients with moderate to severe valvular stenosis or regurgitation. Most bioprosthetic heart valves applied clinically are based on cross-linking with glutaraldehyde (GLUT), but they have some drawbacks like high cytotoxicity, severe calcification, and poor hemocompatibility. In this study, we focused on enhancing the properties of bioprosthetic heart valves by cross-linking with 3,4-dihydroxybenzaldehyde (DHBA). The experiment results revealed that compared with GLUT cross-linked porcine pericardium (PP), the relative amount of platelets absorbed on the surface of DHBA cross-linked PP decreased from 0.294 ± 0.034 to 0.176 ± 0.028, and the activated partial thromboplastin time (APTT) increased from 9.9 ± 0.1 to 15.2 ± 0.1 s, indicating improved hemocompatibility. Moreover, anticalcification performance and cytocompatibility were greatly enhanced by DHBA cross-linking. In conclusion, the properties of bioprosthetic valves could be effectively improved by processing valves with a DHBA-based cross-linking method.
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Affiliation(s)
- Binggang Wu
- National Engineering Research Center for Biomaterials, Sichuan University, No. 29 Wangjiang Road, Chengdu 610064, P. R. China.,Department of Cardiovascular Surgery, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu 610041, P. R. China
| | - Cheng Zheng
- National Engineering Research Center for Biomaterials, Sichuan University, No. 29 Wangjiang Road, Chengdu 610064, P. R. China
| | - Kailei Ding
- National Engineering Research Center for Biomaterials, Sichuan University, No. 29 Wangjiang Road, Chengdu 610064, P. R. China
| | - Xueyu Huang
- National Engineering Research Center for Biomaterials, Sichuan University, No. 29 Wangjiang Road, Chengdu 610064, P. R. China
| | - Meiling Li
- National Engineering Research Center for Biomaterials, Sichuan University, No. 29 Wangjiang Road, Chengdu 610064, P. R. China
| | - Shumang Zhang
- National Engineering Research Center for Biomaterials, Sichuan University, No. 29 Wangjiang Road, Chengdu 610064, P. R. China
| | - Yang Lei
- National Engineering Research Center for Biomaterials, Sichuan University, No. 29 Wangjiang Road, Chengdu 610064, P. R. China
| | - Yingqiang Guo
- Department of Cardiovascular Surgery, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu 610041, P. R. China
| | - Yunbing Wang
- National Engineering Research Center for Biomaterials, Sichuan University, No. 29 Wangjiang Road, Chengdu 610064, P. R. China
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17
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The focal mechanical properties of normal and diseased porcine aortic valve tissue measured by a novel microindentation device. J Mech Behav Biomed Mater 2020; 115:104245. [PMID: 33310684 DOI: 10.1016/j.jmbbm.2020.104245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 11/06/2020] [Accepted: 11/29/2020] [Indexed: 11/20/2022]
Abstract
Cells sense and respond to the heterogeneous mechanical properties of their tissue microenvironment, with implications for the development of many diseases, including cancer, fibrosis, and aortic valve disease. Characterization of tissue mechanical heterogeneity on cellular length scales of tens of micrometers is thus important for understanding disease mechanobiology. In this study, we developed a low-cost bench-top microindentation system to readily map focal microscale soft tissue mechanical properties. The device was validated by comparison with atomic force microscopy nanoindentation of polyacrylamide gels. To demonstrate its utility, the device was used to measure the focal microscale elastic moduli of normal and diseased porcine aortic valve leaflet tissue. Consistent with previous studies, the fibrosa layer of intact leaflets was found to be 1.91-fold stiffer than the ventricularis layer, with both layers exhibiting significant heterogeneity in focal elastic moduli. For the first time, the microscale compressive moduli of focal proteoglycan-rich lesions in the fibrosa of early diseased porcine aortic valve leaflets were measured and found to be 2.44-fold softer than those of normal tissue. These data provide new insights into the tissue micromechanical environment in valvular disease and demonstrate the utility of the microindentation device for facile measurement of the focal mechanical properties of soft tissues.
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18
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Beckett LE, Lewis JT, Tonge TK, Korley LTJ. Enhancement of the Mechanical Properties of Hydrogels with Continuous Fibrous Reinforcement. ACS Biomater Sci Eng 2020; 6:5453-5473. [PMID: 33320571 DOI: 10.1021/acsbiomaterials.0c00911] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Reinforcing mechanically weak hydrogels with fibers is a promising route to obtain strong and tough materials for biomedical applications while retaining a favorable cell environment. The resulting hierarchical structure recreates structural elements of natural tissues such as articular cartilage, with fiber diameters ranging from the nano- to microscale. Through control of properties such as the fiber diameter, orientation, and porosity, it is possible to design materials which display the nonlinear, synergistic mechanical behavior observed in natural tissues. In order to fully exploit these advantages, it is necessary to understand the structure-property relationships in fiber-reinforced hydrogels. However, there are currently limited models which capture their complex mechanical properties. The majority of reported fiber-reinforced hydrogels contain fibers obtained by electrospinning, which allows for limited spatial control over the fiber scaffold and limits the scope for systematic mechanical testing studies. Nevertheless, new manufacturing techniques such as melt electrowriting and bioprinting have emerged, which allow for increased control over fiber deposition and the potential for future investigations on the effect of specific structural features on mechanical properties. In this review, we therefore explore the mechanics of fiber-reinforced hydrogels, and the evolution of their design and manufacture from replicating specific features of biological tissues to more complex structures, by taking advantage of design principles from both tough hydrogels and fiber-reinforced composites. By highlighting the overlap between these fields, it is possible to identify the remaining challenges and opportunities for the development of effective biomedical devices.
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Affiliation(s)
- Laura E Beckett
- University of Delaware, Department of Materials Science and Engineering, 127 The Green, Newark, Delaware 19716, United States
| | - Jackson T Lewis
- W. L. Gore & Associates, Inc., 501 Vieves Way, Elkton, Maryland 21921, United States
| | - Theresa K Tonge
- W. L. Gore & Associates, Inc., 501 Vieves Way, Elkton, Maryland 21921, United States
| | - LaShanda T J Korley
- University of Delaware, Department of Materials Science and Engineering, 127 The Green, Newark, Delaware 19716, United States.,University of Delaware, Department of Chemical and Biomolecular Engineering, 150 Academy Street, Newark, Delaware 19716, United States
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19
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Hsu CPD, Hutcheson JD, Ramaswamy S. Oscillatory fluid-induced mechanobiology in heart valves with parallels to the vasculature. VASCULAR BIOLOGY 2020; 2:R59-R71. [PMID: 32923975 PMCID: PMC7439923 DOI: 10.1530/vb-19-0031] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 02/17/2020] [Indexed: 12/31/2022]
Abstract
Forces generated by blood flow are known to contribute to cardiovascular development and remodeling. These hemodynamic forces induce molecular signals that are communicated from the endothelium to various cell types. The cardiovascular system consists of the heart and the vasculature, and together they deliver nutrients throughout the body. While heart valves and blood vessels experience different environmental forces and differ in morphology as well as cell types, they both can undergo pathological remodeling and become susceptible to calcification. In addition, while the plaque morphology is similar in valvular and vascular diseases, therapeutic targets available for the latter condition are not effective in the management of heart valve calcification. Therefore, research in valvular and vascular pathologies and treatments have largely remained independent. Nonetheless, understanding the similarities and differences in development, calcific/fibrous pathologies and healthy remodeling events between the valvular and vascular systems can help us better identify future treatments for both types of tissues, particularly for heart valve pathologies which have been understudied in comparison to arterial diseases.
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Affiliation(s)
- Chia-Pei Denise Hsu
- Engineering Center, Department of Biomedical Engineering, Florida International University, Miami, Florida, USA
| | - Joshua D Hutcheson
- Engineering Center, Department of Biomedical Engineering, Florida International University, Miami, Florida, USA
| | - Sharan Ramaswamy
- Engineering Center, Department of Biomedical Engineering, Florida International University, Miami, Florida, USA
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20
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Kuznetsov S, Pankow M, Peters K, Huang HYS. A structural-based computational model of tendon-bone insertion tissues. Math Biosci 2020; 327:108411. [PMID: 32623027 DOI: 10.1016/j.mbs.2020.108411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 06/28/2020] [Accepted: 06/28/2020] [Indexed: 10/23/2022]
Abstract
Tendon-to-bone insertion provides a gradual transition from soft tendon to hard bone tissue, functioning to alleviate stress concentrations at the junction of these tissues. Such macroscopic mechanical properties are achieved due to the internal structure in which collagen fibers and mineralization levels are key ingredients. We develop a structural-based model of tendon-to-bone insertion incorporating such details as fiber preferred orientation, fiber directional dispersion, mineralization level, and their inhomogeneous spatial distribution. A python script is developed to alter the tapered tendon-bone transition zone and to provide spatial grading of material properties, which may be rather complex as experiments suggest. A simple linear interpolation between tendon and bone material properties is first used to describe the graded property within the insertion region. Stress distributions are obtained and compared for spatially graded and various piece-wise materials properties. It is observed that spatial grading results in more smooth stress distributions and significantly reduces maximum stresses. The geometry of the tissue model is optimized by minimizing the peak stress to mimic in-vivo tissue remodeling. The in-silico elastic models constructed in this work are verified and modified by comparing to our in-situ biaxial mechanical testing results, thereby serving as translational tools for accurately predicting the material behavior of the tendon-to-bone insertions. This model will be useful for understanding how tendon-to-bone insertion develops during tissue remodeling, as well as for developing orthopedic implants.
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Affiliation(s)
| | - Mark Pankow
- North Carolina State University, United States of America
| | - Kara Peters
- North Carolina State University, United States of America
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21
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Nachlas ALY, Li S, Streeter BW, De Jesus Morales KJ, Sulejmani F, Madukauwa-David DI, Bejleri D, Sun W, Yoganathan AP, Davis ME. A multilayered valve leaflet promotes cell-laden collagen type I production and aortic valve hemodynamics. Biomaterials 2020; 240:119838. [PMID: 32092591 DOI: 10.1016/j.biomaterials.2020.119838] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 01/27/2020] [Accepted: 01/31/2020] [Indexed: 12/18/2022]
Abstract
Patients with aortic heart valve disease are limited to valve replacements that lack the ability to grow and remodel. This presents a major challenge for pediatric patients who require a valve capable of somatic growth and at a smaller size. A patient-specific heart valve capable of growth and remodeling while maintaining proper valve function would address this major issue. Here, we recreate the native valve leaflet structure composed of poly-ε-caprolactone (PCL) and cell-laden gelatin-methacrylate/poly (ethylene glycol) diacrylate (GelMA/PEGDA) hydrogels using 3D printing and molding, and then evaluate the ability of the multilayered scaffold to produce collagen matrix under physiological shear stress conditions. We also characterized the valve hemodynamics under aortic physiological flow conditions. The valve's fibrosa layer was replicated by 3D printing PCL in a circumferential direction similar to collagen alignment in the native leaflet, and GelMA/PEGDA sustained and promoted cell viability in the spongiosa/ventricularis layers. We found that collagen type I production can be increased in the multilayered scaffold when it is exposed to pulsatile shear stress conditions over static conditions. When the PCL component was mounted onto a valve ring and tested under physiological aortic valve conditions, the hemodynamics were comparable to commercially available valves. Our results demonstrate that a structurally representative valve leaflet can be generated using 3D printing and that the PCL layer of the leaflet can sustain proper valve function under physiological aortic valve conditions.
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Affiliation(s)
- Aline L Y Nachlas
- Wallace H Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
| | - Siyi Li
- Wallace H Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
| | - Benjamin W Streeter
- Wallace H Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
| | - Kenneth J De Jesus Morales
- Wallace H Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
| | - Fatiesa Sulejmani
- Wallace H Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
| | - David Immanuel Madukauwa-David
- Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, GA, USA; George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Donald Bejleri
- Wallace H Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
| | - Wei Sun
- Wallace H Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
| | - Ajit P Yoganathan
- Wallace H Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
| | - Michael E Davis
- Wallace H Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA; Children's Heart Research & Outcomes (HeRO) Center, Children's Healthcare of Atlanta & Emory University, Atlanta, GA, USA.
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22
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Li RL, Russ J, Paschalides C, Ferrari G, Waisman H, Kysar JW, Kalfa D. Mechanical considerations for polymeric heart valve development: Biomechanics, materials, design and manufacturing. Biomaterials 2019; 225:119493. [PMID: 31569017 PMCID: PMC6948849 DOI: 10.1016/j.biomaterials.2019.119493] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 08/21/2019] [Accepted: 09/11/2019] [Indexed: 01/12/2023]
Abstract
The native human heart valve leaflet contains a layered microstructure comprising a hierarchical arrangement of collagen, elastin, proteoglycans and various cell types. Here, we review the various experimental methods that have been employed to probe this intricate microstructure and which attempt to elucidate the mechanisms that govern the leaflet's mechanical properties. These methods include uniaxial, biaxial, and flexural tests, coupled with microstructural characterization techniques such as small angle X-ray scattering (SAXS), small angle light scattering (SALS), and polarized light microscopy. These experiments have revealed complex elastic and viscoelastic mechanisms that are highly directional and dependent upon loading conditions and biochemistry. Of all engineering materials, polymers and polymer-based composites are best able to mimic the tissue-level mechanical behavior of the native leaflet. This similarity to native tissue permits the fabrication of polymeric valves with physiological flow patterns, reducing the risk of thrombosis compared to mechanical valves and in some cases surpassing the in vivo durability of bioprosthetic valves. Earlier work on polymeric valves simply assumed the mechanical properties of the polymer material to be linear elastic, while more recent studies have considered the full hyperelastic stress-strain response. These material models have been incorporated into computational models for the optimization of valve geometry, with the goal of minimizing internal stresses and improving durability. The latter portion of this review recounts these developments in polymeric heart valves, with a focus on mechanical testing of polymers, valve geometry, and manufacturing methods.
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Affiliation(s)
- Richard L Li
- Department of Mechanical Engineering, Fu Foundation School of Engineering and Applied Science, Columbia University, New York, NY, USA; Division of Cardiac, Thoracic and Vascular Surgery, Section of Pediatric and Congenital Cardiac Surgery, New-York Presbyterian - Morgan Stanley Children's Hospital, Columbia University Medical Center, New York, NY, USA
| | - Jonathan Russ
- Department of Civil Engineering and Engineering Mechanics, Fu Foundation School of Engineering and Applied Science, Columbia University, New York, NY, USA
| | - Costas Paschalides
- Department of Mechanical Engineering, Fu Foundation School of Engineering and Applied Science, Columbia University, New York, NY, USA
| | - Giovanni Ferrari
- Department of Surgery and Biomedical Engineering, Columbia University Medical Center, New York, NY, USA
| | - Haim Waisman
- Department of Civil Engineering and Engineering Mechanics, Fu Foundation School of Engineering and Applied Science, Columbia University, New York, NY, USA
| | - Jeffrey W Kysar
- Department of Mechanical Engineering, Fu Foundation School of Engineering and Applied Science, Columbia University, New York, NY, USA; Department of Otolaryngology - Head and Neck Surgery, Columbia University Medical Center, New York, NY, USA.
| | - David Kalfa
- Division of Cardiac, Thoracic and Vascular Surgery, Section of Pediatric and Congenital Cardiac Surgery, New-York Presbyterian - Morgan Stanley Children's Hospital, Columbia University Medical Center, New York, NY, USA.
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23
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Kramer KE, Ross CJ, Laurence DW, Babu AR, Wu Y, Towner RA, Mir A, Burkhart HM, Holzapfel GA, Lee CH. An investigation of layer-specific tissue biomechanics of porcine atrioventricular valve anterior leaflets. Acta Biomater 2019; 96:368-384. [PMID: 31260822 PMCID: PMC6717680 DOI: 10.1016/j.actbio.2019.06.049] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 06/24/2019] [Accepted: 06/26/2019] [Indexed: 12/29/2022]
Abstract
Atrioventricular heart valves (AHVs) are composed of structurally complex and morphologically heterogeneous leaflets. The coaptation of these leaflets during the cardiac cycle facilitates unidirectional blood flow. Valve regurgitation is treated preferably by surgical repair if possible or replacement based on the disease state of the valve tissue. A comprehensive understanding of valvular morphology and mechanical properties is crucial to refining computational models, serving as a patient-specific diagnostic and surgical tool for preoperative planning. Previous studies have modeled the stress distribution throughout the leaflet's thickness, but validations with layer-specific biaxial mechanical experiments are missing. In this study, we sought to fill this gap in literature by investigating the impact of microstructure constituents on mechanical behavior throughout the thickness of the AHVs' anterior leaflets. Porcine mitral valve anterior leaflets (MVAL) and tricuspid valve anterior leaflets (TVAL) were micro-dissected into three layers (atrialis/spongiosa, fibrosa, and ventricular) and two layers (atrialis/spongiosa and fibrosa/ventricularis), respectively, based on their relative distributions of extracellular matrix components as quantified by histological analyses: collagen, elastin, and glycosaminoglycans. Our results suggest that (i) for both valves, the atrialis/spongiosa layer is the most extensible and anisotropic layer, possibly due to its relatively low collagen content as compared to other layers, (ii) the intact TVAL response is stiffer than the atrialis/spongiosa layer but more compliant than the fibrosa/ventricularis layer, and (iii) the MVAL fibrosa and ventricularis layers behave nearly isotropic. These novel findings emphasize the biomechanical variances throughout the AHV leaflets, and our results could better inform future AHV computational model developments. STATEMENT OF SIGNIFICANCE: This study, which is the first of its kind for atrioventricular heart valve (AHV) leaflet tissue layers, rendered a mechanical characterization of the biaxial mechanical properties and distributions of extracellular matrix components (collagen, elastin, and glycosaminoglycans) of the mitral and tricuspid valve anterior leaflet layers. The novel findings from the present study emphasize the biomechanical variances throughout the thickness of AHV leaflets, and our results indicate that the previously-adopted homogenous leaflet in the AHV biomechanical modeling may be an oversimplification of the complex leaflet anatomy. Such improvement in the understanding of valvular morphology and tissue mechanics is crucial to future refinement of AHV computational models, serving as a patient-specific diagnostic and surgical tool, at the preoperative stage, for treating valvular heart diseases.
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Affiliation(s)
- Katherine E Kramer
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA
| | - Colton J Ross
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA
| | - Devin W Laurence
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA
| | - Anju R Babu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA
| | - Yi Wu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA
| | - Rheal A Towner
- Advanced Magnetic Resonance Center, MS 60, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
| | - Arshid Mir
- Division of Pediatric Cardiology, Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Harold M Burkhart
- Division of Cardiothoracic Surgery, Department of Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Graz, Austria; Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA; Institute for Biomedical Engineering, Science and Technology, The University of Oklahoma, Norman, OK 73019, USA.
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24
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Ross CJ, Laurence DW, Richardson J, Babu AR, Evans LE, Beyer EG, Childers RC, Wu Y, Towner RA, Fung KM, Mir A, Burkhart HM, Holzapfel GA, Lee CH. An investigation of the glycosaminoglycan contribution to biaxial mechanical behaviours of porcine atrioventricular heart valve leaflets. J R Soc Interface 2019; 16:20190069. [PMID: 31266416 PMCID: PMC6685018 DOI: 10.1098/rsif.2019.0069] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Accepted: 06/03/2019] [Indexed: 01/06/2023] Open
Abstract
The atrioventricular heart valve (AHV) leaflets have a complex microstructure composed of four distinct layers: atrialis, ventricularis, fibrosa and spongiosa. Specifically, the spongiosa layer is primarily proteoglycans and glycosaminoglycans (GAGs). Quantification of the GAGs' mechanical contribution to the overall leaflet function has been of recent focus for aortic valve leaflets, but this characterization has not been reported for the AHV leaflets. This study seeks to expand current GAG literature through novel mechanical characterizations of GAGs in AHV leaflets. For this characterization, mitral and tricuspid valve anterior leaflets (MVAL and TVAL, respectively) were: (i) tested by biaxial mechanical loading at varying loading ratios and by stress-relaxation procedures, (ii) enzymatically treated for removal of the GAGs and (iii) biaxially mechanically tested again under the same protocols as in step (i). Removal of the GAG contents from the leaflet was conducted using a 100 min enzyme treatment to achieve approximate 74.87% and 61.24% reductions of all GAGs from the MVAL and TVAL, respectively. Our main findings demonstrated that biaxial mechanical testing yielded a statistically significant difference in tissue extensibility after GAG removal and that stress-relaxation testing revealed a statistically significant smaller stress decay of the enzyme-treated tissue than untreated tissues. These novel findings illustrate the importance of GAGs in AHV leaflet behaviour, which can be employed to better inform heart valve therapeutics and computational models.
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Affiliation(s)
- Colton J. Ross
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, USA
| | - Devin W. Laurence
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, USA
| | - Jacob Richardson
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, USA
| | - Anju R. Babu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, USA
| | - Lauren E. Evans
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, USA
| | - Ean G. Beyer
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, USA
| | - Rachel C. Childers
- Stephenson School of Biomedical Engineering, The University of Oklahoma, Norman, OK, USA
| | - Yi Wu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, USA
| | - Rheal A. Towner
- Advanced Magnetic Resonance Center, MS 60, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Kar-Ming Fung
- Department of Pathology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Stephenson Cancer Center, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Arshid Mir
- Division of Pediatric Cardiology, Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Harold M. Burkhart
- Division of Cardiothoracic Surgery, Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Gerhard A. Holzapfel
- Institute of Biomechanics, Graz University of Technology, Graz, Austria
- Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, USA
- Institute for Biomedical Engineering, Science and Technology, The University of Oklahoma, Norman, OK, USA
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25
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Saidy NT, Wolf F, Bas O, Keijdener H, Hutmacher DW, Mela P, De-Juan-Pardo EM. Biologically Inspired Scaffolds for Heart Valve Tissue Engineering via Melt Electrowriting. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1900873. [PMID: 31058444 DOI: 10.1002/smll.201900873] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 04/14/2019] [Indexed: 06/09/2023]
Abstract
Heart valves are characterized to be highly flexible yet tough, and exhibit complex deformation characteristics such as nonlinearity, anisotropy, and viscoelasticity, which are, at best, only partially recapitulated in scaffolds for heart valve tissue engineering (HVTE). These biomechanical features are dictated by the structural properties and microarchitecture of the major tissue constituents, in particular collagen fibers. In this study, the unique capabilities of melt electrowriting (MEW) are exploited to create functional scaffolds with highly controlled fibrous microarchitectures mimicking the wavy nature of the collagen fibers and their load-dependent recruitment. Scaffolds with precisely-defined serpentine architectures reproduce the J-shaped strain stiffening, anisotropic and viscoelastic behavior of native heart valve leaflets, as demonstrated by quasistatic and dynamic mechanical characterization. They also support the growth of human vascular smooth muscle cells seeded both directly or encapsulated in fibrin, and promote the deposition of valvular extracellular matrix components. Finally, proof-of-principle MEW trileaflet valves display excellent acute hydrodynamic performance under aortic physiological conditions in a custom-made flow loop. The convergence of MEW and a biomimetic design approach enables a new paradigm for the manufacturing of scaffolds with highly controlled microarchitectures, biocompatibility, and stringent nonlinear and anisotropic mechanical properties required for HVTE.
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Affiliation(s)
- Navid T Saidy
- Centre in Regenerative Medicine, Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology (QUT), 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland, 4059, Australia
- Department of Biohybrid & Medical Textiles (BioTex), AME-Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Frederic Wolf
- Department of Biohybrid & Medical Textiles (BioTex), AME-Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Onur Bas
- Centre in Regenerative Medicine, Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology (QUT), 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland, 4059, Australia
- ARC ITTC in Additive Biomanufacturing, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland, 4059, Australia
| | - Hans Keijdener
- Department of Biohybrid & Medical Textiles (BioTex), AME-Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
| | - Dietmar W Hutmacher
- Centre in Regenerative Medicine, Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology (QUT), 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland, 4059, Australia
- ARC ITTC in Additive Biomanufacturing, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland, 4059, Australia
- Institute for Advanced Study, Technische Universität München, D-85748, Garching, Germany
| | - Petra Mela
- Department of Biohybrid & Medical Textiles (BioTex), AME-Institute of Applied Medical Engineering, Helmholtz Institute, RWTH Aachen University, Forckenbeckstr. 55, 52074, Aachen, Germany
- Medical Materials and Medical Implant Design, Department of Mechanical Engineering, Technical University of Munich, Boltzmannstr. 15, 85748, Garching,
| | - Elena M De-Juan-Pardo
- Centre in Regenerative Medicine, Institute of Health and Biomedical Innovation (IHBI), Queensland University of Technology (QUT), 60 Musk Avenue, Kelvin Grove, Brisbane, Queensland, 4059, Australia
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26
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Xu K, Huang Y, Zhou T, Wang C, Chi Q, Shi J, Zhu P, Dong N. Nobiletin exhibits potent inhibition on tumor necrosis factor alpha‐induced calcification of human aortic valve interstitial cells via targeting ABCG2 and AKR1B1. Phytother Res 2019; 33:1717-1725. [PMID: 31016813 DOI: 10.1002/ptr.6360] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/25/2019] [Accepted: 03/06/2019] [Indexed: 01/28/2023]
Affiliation(s)
- Kang Xu
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical CollegeHuazhong University of Science and Technology Wuhan China
| | - Yuming Huang
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical CollegeHuazhong University of Science and Technology Wuhan China
| | - Tingwen Zhou
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical CollegeHuazhong University of Science and Technology Wuhan China
| | - Chunli Wang
- National Innovation and Attracting Talents “111” base, Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of BioengineeringChongqing University Chongqing China
| | - Qingjia Chi
- Department of Mechanics and Engineering Structure, Hubei Key Laboratory of Theory and Application of Advanced Materials MechanicsWuhan University of Technology Wuhan China
| | - Jiawei Shi
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical CollegeHuazhong University of Science and Technology Wuhan China
| | - Peng Zhu
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical CollegeHuazhong University of Science and Technology Wuhan China
| | - Nianguo Dong
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical CollegeHuazhong University of Science and Technology Wuhan China
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27
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Jin L, Guo G, Jin W, Lei Y, Wang Y. Cross-Linking Methacrylated Porcine Pericardium by Radical Polymerization Confers Enhanced Extracellular Matrix Stability, Reduced Calcification, and Mitigated Immune Response to Bioprosthetic Heart Valves. ACS Biomater Sci Eng 2019; 5:1822-1832. [DOI: 10.1021/acsbiomaterials.9b00091] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Linhe Jin
- National Engineering Research Center for Biomaterials, Sichuan University, No. 24 South Section 1 Yihuan Road, Chengdu 610064, P. R. China
| | - Gaoyang Guo
- National Engineering Research Center for Biomaterials, Sichuan University, No. 24 South Section 1 Yihuan Road, Chengdu 610064, P. R. China
| | - Wanyu Jin
- National Engineering Research Center for Biomaterials, Sichuan University, No. 24 South Section 1 Yihuan Road, Chengdu 610064, P. R. China
| | - Yang Lei
- National Engineering Research Center for Biomaterials, Sichuan University, No. 24 South Section 1 Yihuan Road, Chengdu 610064, P. R. China
| | - Yunbing Wang
- National Engineering Research Center for Biomaterials, Sichuan University, No. 24 South Section 1 Yihuan Road, Chengdu 610064, P. R. China
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28
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Gomel MA, Lee R, Grande-Allen KJ. Comparing the Role of Mechanical Forces in Vascular and Valvular Calcification Progression. Front Cardiovasc Med 2019; 5:197. [PMID: 30687719 PMCID: PMC6335252 DOI: 10.3389/fcvm.2018.00197] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 12/20/2018] [Indexed: 01/07/2023] Open
Abstract
Calcification is a prevalent disease in most fully developed countries and is predominantly observed in heart valves and nearby vasculature. Calcification of either tissue leads to deterioration and, ultimately, failure causing poor quality of life and decreased overall life expectancy in patients. In valves, calcification presents as Calcific Aortic Valve Disease (CAVD), in which the aortic valve becomes stenotic when calcific nodules form within the leaflets. The initiation and progression of these calcific nodules is strongly influenced by the varied mechanical forces on the valve. In turn, the addition of calcific nodules creates localized disturbances in the tissue biomechanics, which affects extracellular matrix (ECM) production and cellular activation. In vasculature, atherosclerosis is the most common occurrence of calcification. Atherosclerosis exhibits as calcific plaque formation that forms in juxtaposition to areas of low blood shear stresses. Research in these two manifestations of calcification remain separated, although many similarities persist. Both diseases show that the endothelial layer and its regulation of nitric oxide is crucial to calcification progression. Further, there are similarities between vascular smooth muscle cells and valvular interstitial cells in terms of their roles in ECM overproduction. This review summarizes valvular and vascular tissue in terms of their basic anatomy, their cellular and ECM components and mechanical forces. Calcification is then examined in both tissues in terms of disease prediction, progression, and treatment. Highlighting the similarities and differences between these areas will help target further research toward disease treatment.
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29
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Engineering a 3D-Bioprinted Model of Human Heart Valve Disease Using Nanoindentation-Based Biomechanics. NANOMATERIALS 2018; 8:nano8050296. [PMID: 29751516 PMCID: PMC5977310 DOI: 10.3390/nano8050296] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 04/18/2018] [Accepted: 04/24/2018] [Indexed: 01/18/2023]
Abstract
In calcific aortic valve disease (CAVD), microcalcifications originating from nanoscale calcifying vesicles disrupt the aortic valve (AV) leaflets, which consist of three (biomechanically) distinct layers: the fibrosa, spongiosa, and ventricularis. CAVD has no pharmacotherapy and lacks in vitro models as a result of complex valvular biomechanical features surrounding resident mechanosensitive valvular interstitial cells (VICs). We measured layer-specific mechanical properties of the human AV and engineered a three-dimensional (3D)-bioprinted CAVD model that recapitulates leaflet layer biomechanics for the first time. Human AV leaflet layers were separated by microdissection, and nanoindentation determined layer-specific Young’s moduli. Methacrylated gelatin (GelMA)/methacrylated hyaluronic acid (HAMA) hydrogels were tuned to duplicate layer-specific mechanical characteristics, followed by 3D-printing with encapsulated human VICs. Hydrogels were exposed to osteogenic media (OM) to induce microcalcification, and VIC pathogenesis was assessed by near infrared or immunofluorescence microscopy. Median Young’s moduli of the AV layers were 37.1, 15.4, and 26.9 kPa (fibrosa/spongiosa/ventricularis, respectively). The fibrosa and spongiosa Young’s moduli matched the 3D 5% GelMa/1% HAMA UV-crosslinked hydrogels. OM stimulation of VIC-laden bioprinted hydrogels induced microcalcification without apoptosis. We report the first layer-specific measurements of human AV moduli and a novel 3D-bioprinted CAVD model that potentiates microcalcification by mimicking the native AV mechanical environment. This work sheds light on valvular mechanobiology and could facilitate high-throughput drug-screening in CAVD.
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30
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Blum KM, Drews JD, Breuer CK. Tissue-Engineered Heart Valves: A Call for Mechanistic Studies. TISSUE ENGINEERING PART B-REVIEWS 2018; 24:240-253. [PMID: 29327671 DOI: 10.1089/ten.teb.2017.0425] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Heart valve disease carries a substantial risk of morbidity and mortality. Outcomes are significantly improved by valve replacement, but currently available mechanical and biological replacement valves are associated with complications of their own. Mechanical valves have a high rate of thromboembolism and require lifelong anticoagulation. Biological prosthetic valves have a much shorter lifespan, and they are prone to tearing and degradation. Both types of valves lack the capacity for growth, making them particularly problematic in pediatric patients. Tissue engineering has the potential to overcome these challenges by creating a neovalve composed of native tissue that is capable of growth and remodeling. The first tissue-engineered heart valve (TEHV) was created more than 20 years ago in an ovine model, and the technology has been advanced to clinical trials in the intervening decades. Some TEHVs have had clinical success, whereas others have failed, with structural degeneration resulting in patient deaths. The etiologies of these complications are poorly understood because much of the research in this field has been performed in large animals and humans, and, therefore, there are few studies of the mechanisms of neotissue formation. This review examines the need for a TEHV to treat pediatric patients with valve disease, the history of TEHVs, and a future that would benefit from extension of the reverse translational trend in this field to include small animal studies.
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Affiliation(s)
- Kevin M Blum
- 1 Center for Regenerative Medicine, The Research Institute at Nationwide Children's Hospital , Columbus, Ohio.,2 The Ohio State University College of Medicine , Columbus, Ohio
| | - Joseph D Drews
- 1 Center for Regenerative Medicine, The Research Institute at Nationwide Children's Hospital , Columbus, Ohio.,3 Department of Surgery, The Ohio State University Wexner Medical Center , Columbus, Ohio
| | - Christopher K Breuer
- 1 Center for Regenerative Medicine, The Research Institute at Nationwide Children's Hospital , Columbus, Ohio.,3 Department of Surgery, The Ohio State University Wexner Medical Center , Columbus, Ohio
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31
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Nachlas ALY, Li S, Davis ME. Developing a Clinically Relevant Tissue Engineered Heart Valve-A Review of Current Approaches. Adv Healthc Mater 2017; 6. [PMID: 29171921 DOI: 10.1002/adhm.201700918] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/25/2017] [Indexed: 11/08/2022]
Abstract
Tissue engineered heart valves (TEHVs) have the potential to address the shortcomings of current implants through the combination of cells and bioactive biomaterials that promote growth and proper mechanical function in physiological conditions. The ideal TEHV should be anti-thrombogenic, biocompatible, durable, and resistant to calcification, and should exhibit a physiological hemodynamic profile. In addition, TEHVs may possess the capability to integrate and grow with somatic growth, eliminating the need for multiple surgeries children must undergo. Thus, this review assesses clinically available heart valve prostheses, outlines the design criteria for developing a heart valve, and evaluates three types of biomaterials (decellularized, natural, and synthetic) for tissue engineering heart valves. While significant progress has been made in biomaterials and fabrication techniques, a viable tissue engineered heart valve has yet to be translated into a clinical product. Thus, current strategies and future perspectives are also discussed to facilitate the development of new approaches and considerations for heart valve tissue engineering.
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Affiliation(s)
- Aline L. Y. Nachlas
- Wallace H Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University Atlanta GA 30332 USA
| | - Siyi Li
- Wallace H Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University Atlanta GA 30332 USA
| | - Michael E. Davis
- Wallace H Coulter Department of Biomedical Engineering Georgia Institute of Technology and Emory University Atlanta GA 30332 USA
- Children's Heart Research & Outcomes (HeRO) Center Children's Healthcare of Atlanta & Emory University Atlanta GA 30322 USA
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32
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Carleton JB, Rodin GJ, Sacks MS. Layered Elastomeric Fibrous Scaffolds: An In-Silico Study of the Achievable Range of Mechanical Behaviors. ACS Biomater Sci Eng 2017; 3:2907-2921. [DOI: 10.1021/acsbiomaterials.7b00308] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- James B. Carleton
- Center
for Cardiovascular Simulation, Institute for Computational Engineering
and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th Street, Austin, Texas 78712, United States
| | - Gregory J. Rodin
- Center
for Cardiovascular Simulation, Institute for Computational Engineering
and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th Street, Austin, Texas 78712, United States
- Department
of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, 210 East 24th Street, Austin, Texas 78712, United States
| | - Michael S. Sacks
- Center
for Cardiovascular Simulation, Institute for Computational Engineering
and Sciences and the Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th Street, Austin, Texas 78712, United States
- Department
of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, 210 East 24th Street, Austin, Texas 78712, United States
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33
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Arzani A, Masters KS, Mofrad MRK. Multiscale Systems Biology Model of Calcific Aortic Valve Disease Progression. ACS Biomater Sci Eng 2017; 3:2922-2933. [DOI: 10.1021/acsbiomaterials.7b00174] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Amirhossein Arzani
- Molecular
Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical
Engineering, University of California, Berkeley, California 94720, United States
| | - Kristyn S. Masters
- Department
of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Mohammad R. K. Mofrad
- Molecular
Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical
Engineering, University of California, Berkeley, California 94720, United States
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34
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Dahal S, Huang P, Murray BT, Mahler GJ. Endothelial to mesenchymal transformation is induced by altered extracellular matrix in aortic valve endothelial cells. J Biomed Mater Res A 2017; 105:2729-2741. [PMID: 28589644 DOI: 10.1002/jbm.a.36133] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 05/09/2017] [Accepted: 06/01/2017] [Indexed: 11/10/2022]
Abstract
Alterations in shear stress, mechanical deformation, extracellular matrix (ECM) composition and exposure to inflammatory conditions are known to cause endothelial to mesenchymal transformation (EndMT). This change in endothelial phenotype has only recently been linked to adult pathologies such as cancer progression, organ fibrosis, and calcific aortic valve disease; and its function in adult physiology, especially in response to tissue mechanics, has not been rigorously investigated. EndMT is a response to mechanical and biochemical signals that results in the remodeling of underlying tissues. In diseased aortic valves, glycosaminoglycans (GAGs) are present in the collagen-rich valve fibrosa, and are deposited near calcified nodules. In this study, in vitro models of early and late-stage valve disease were developed by incorporating the GAGs chondroitin sulfate (CS), hyaluronic acid, and dermatan sulfate into 3D collagen hydrogels with or without exposure to TGF-β1 to simulate EndMT in response to microenvironmental changes. High levels of CS induced the highest rate of EndMT and led to the most collagen I and GAG production by mesenchymally transformed cells, which indicates a cell phenotype most likely to promote fibrotic disease. Mesenchymal transformation due to altered ECM was found to depend on cell-ECM bond strength and extracellular signal-regulated protein kinases 1/2 signaling. Determining the environmental conditions that induce and promote EndMT, and the subsequent behavior of mesenchymally transformed cells, will advance understanding on the role of endothelial cells in tissue regeneration or disease progression. © 2017 Wiley Periodicals Inc. J Biomed Mater Res Part A: 105A: 2729-2741, 2017.
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Affiliation(s)
- Sudip Dahal
- Department of Biomedical Engineering, Binghamton University, Binghamton, New York, USA
| | - Peter Huang
- Department of Mechanical Engineering, Binghamton University, Binghamton, New York, USA
| | - Bruce T Murray
- Department of Mechanical Engineering, Binghamton University, Binghamton, New York, USA
| | - Gretchen J Mahler
- Department of Biomedical Engineering, Binghamton University, Binghamton, New York, USA
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35
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Cirka HA, Uribe J, Liang V, Schoen FJ, Billiar KL. Reproducible in vitro model for dystrophic calcification of cardiac valvular interstitial cells: insights into the mechanisms of calcific aortic valvular disease. LAB ON A CHIP 2017; 17:814-829. [PMID: 28128382 DOI: 10.1039/c6lc01226d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Calcific aortic valvular disease (CAVD) is the most prevalent valvular pathology in the United States. Development of a pharmacologic agent to slow, halt, or reverse calcification has proven to be unsuccessful as still much remains unknown about the mechanisms of disease initiation. Although in vitro models of some features of CAVD exist, their utility is limited by the inconsistency of the size and time course of the calcified cell aggregates. In this study, we introduce and verify a highly reproducible in vitro method for studying dystrophic calcification of cardiac valvular interstitial cells, considered to be a key mechanism of clinical CAVD. By utilizing micro-contact printing, we were able to consistently reproduce cell aggregation, myofibroblastic markers, programmed cell death, and calcium accumulation within aggregates of 50-400 μm in diameter on substrates with moduli from 9.6 to 76.8 kPa. This method is highly repeatable, with 70% of aggregates staining positive for Alizarin Red S after one week in culture. Dense mineralized calcium-positive nanoparticles were found within the valvular interstitial cell aggregates as shown by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The area of micro-contact printed aggregates staining positive for caspase 3/7 activity increased from 5.9 ± 0.9% to 12.6 ± 4.5% over one week in culture. Z-VAD-FMK reduced aggregates staining positive for Alizarin Red S by 60%. The state of cell stress is hypothesized to play a role in the disease progression; traction force microscopy indicates high substrate stresses along the aggregate periphery which can be modulated by altering the size of the aggregates and the modulus of the substrate. Micro-contact printing is advantageous over the currently used in vitro model as it allows the independent study of how cytokines, substrate modulus, and pharmacologic agents affect calcification. This controlled method for aggregate creation has the potential to be used as an in vitro assay for the screening of promising therapeutics to mitigate CAVD.
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Affiliation(s)
- Heather A Cirka
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, USA.
| | - Johana Uribe
- Department of Bioengineering, University of Massachusetts at Dartmouth, Dartmouth, MA 02714, USA
| | - Vivian Liang
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, USA.
| | - Frederick J Schoen
- Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Kristen L Billiar
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, USA.
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36
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A functionally graded material model for the transmural stress distribution of the aortic valve leaflet. J Biomech 2017; 54:88-95. [PMID: 28256242 DOI: 10.1016/j.jbiomech.2017.01.039] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 12/02/2016] [Accepted: 01/28/2017] [Indexed: 11/22/2022]
Abstract
Heterogeneities in structure and stress within heart valve leaflets are of significant concern to their functional physiology, as they affect how the tissue constituents remodel in response to pathological and non-pathological (e.g. exercise, pregnancy) alterations in cardiac function. Indeed, valve interstitial cells (VICs) are known to synthesize and degrade leaflet extracellular matrix (ECM) components in a manner specific to their local micromechanical environment. Quantifying local variations in ECM structure and stress is thus necessary to understand homeostatic valve maintenance as well as to develop predictive models of disease progression and post-surgical outcomes. In the aortic valve (AV), transmural variations in stress have previously been investigated by modeling the leaflet as a composite of contiguous but mechanically distinct layers. Based on previous findings about the bonded nature of these layers (Buchanan and Sacks, BMMB, 2014), we developed a more generalized structural constitutive model by treating the leaflet as a functionally graded material (FGM), whose properties vary continuously over the thickness. We informed the FGM model using high-resolution morphological measurements, which demonstrated that the composition and fiber structure change gradually over the thickness of the AV leaflet. For validation, we fit the model against an extensive database of whole-leaflet and individual-layer mechanical responses. The FGM model predicted large stress variations both between and within the leaflet layers at end-diastole, with low-collagen regions bearing significant radial stress. These novel results suggest that the continually varying structure of the AV leaflet has an important purpose with regard to valve function and tissue homeostasis.
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37
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Xue Y, Sant V, Phillippi J, Sant S. Biodegradable and biomimetic elastomeric scaffolds for tissue-engineered heart valves. Acta Biomater 2017; 48:2-19. [PMID: 27780764 DOI: 10.1016/j.actbio.2016.10.032] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 10/13/2016] [Accepted: 10/22/2016] [Indexed: 01/04/2023]
Abstract
Valvular heart diseases are the third leading cause of cardiovascular disease, resulting in more than 25,000 deaths annually in the United States. Heart valve tissue engineering (HVTE) has emerged as a putative treatment strategy such that the designed construct would ideally withstand native dynamic mechanical environment, guide regeneration of the diseased tissue and more importantly, have the ability to grow with the patient. These desired functions could be achieved by biomimetic design of tissue-engineered constructs that recapitulate in vivo heart valve microenvironment with biomimetic architecture, optimal mechanical properties and possess suitable biodegradability and biocompatibility. Synthetic biodegradable elastomers have gained interest in HVTE due to their excellent mechanical compliance, controllable chemical structure and tunable degradability. This review focuses on the state-of-art strategies to engineer biomimetic elastomeric scaffolds for HVTE. We first discuss the various types of biodegradable synthetic elastomers and their key properties. We then highlight tissue engineering approaches to recreate some of the features in the heart valve microenvironment such as anisotropic and hierarchical tri-layered architecture, mechanical anisotropy and biocompatibility. STATEMENT OF SIGNIFICANCE Heart valve tissue engineering (HVTE) is of special significance to overcome the drawbacks of current valve replacements. Although biodegradable synthetic elastomers have emerged as promising materials for HVTE, a mature HVTE construct made from synthetic elastomers for clinical use remains to be developed. Hence, this review summarized various types of biodegradable synthetic elastomers and their key properties. The major focus that distinguishes this review from the current literature is the thorough discussion on the key features of native valve microenvironments and various up-and-coming approaches to engineer synthetic elastomers to recreate these features such as anisotropic tri-layered architecture, mechanical anisotropy, biodegradability and biocompatibility. This review is envisioned to inspire and instruct the design of functional HVTE constructs and facilitate their clinical translation.
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Zhang X, Xu B, Puperi DS, Wu Y, West JL, Grande-Allen KJ. Application of hydrogels in heart valve tissue engineering. J Long Term Eff Med Implants 2016; 25:105-34. [PMID: 25955010 DOI: 10.1615/jlongtermeffmedimplants.2015011817] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
With an increasing number of patients requiring valve replacements, there is heightened interest in advancing heart valve tissue engineering (HVTE) to provide solutions to the many limitations of current surgical treatments. A variety of materials have been developed as scaffolds for HVTE including natural polymers, synthetic polymers, and decellularized valvular matrices. Among them, biocompatible hydrogels are generating growing interest. Natural hydrogels, such as collagen and fibrin, generally show good bioactivity but poor mechanical durability. Synthetic hydrogels, on the other hand, have tunable mechanical properties; however, appropriate cell-matrix interactions are difficult to obtain. Moreover, hydrogels can be used as cell carriers when the cellular component is seeded into the polymer meshes or decellularized valve scaffolds. In this review, we discuss current research strategies for HVTE with an emphasis on hydrogel applications. The physicochemical properties and fabrication methods of these hydrogels, as well as their mechanical properties and bioactivities are described. Performance of some hydrogels including in vitro evaluation using bioreactors and in vivo tests in different animal models are also discussed. For future HVTE, it will be compelling to examine how hydrogels can be constructed from composite materials to replicate mechanical properties and mimic biological functions of the native heart valve.
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Affiliation(s)
- Xing Zhang
- Department of Bioengineering, Rice University, Houston, TX 77030, USA; Institute of Metal Research, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
| | - Bin Xu
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
| | - Daniel S Puperi
- Department of Bioengineering, Rice University, Houston, TX 77030, USA
| | - Yan Wu
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Jennifer L West
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
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Wu Y, Grande-Allen KJ, West JL. Adhesive Peptide Sequences Regulate Valve Interstitial Cell Adhesion, Phenotype and Extracellular Matrix Deposition. Cell Mol Bioeng 2016; 9:479-495. [PMID: 28220141 PMCID: PMC5315271 DOI: 10.1007/s12195-016-0451-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 05/30/2016] [Indexed: 12/13/2022] Open
Abstract
Knowledge of how extracellular matrix (ECM) binding impacts valve interstitial cells (VICs) is critical not only to better understanding the etiology of valvular diseases but also to constructing living valve substitutes that can grow and remodel. Use of ECM-mimicking adhesive peptides with specific affinity to different receptors provides insights into adhesion-mediated cell signaling and downstream outcomes. Expression of adhesion receptors by VICs was assessed by flow cytometry and used to guide the choice of peptides studied. The peptide RGDS with affinity to multiple integrin receptors, and specific receptor-targeting peptides DGEA (integrin α2β1), YIGSR (67kDa laminin/elastin receptor; 67LR), and VAPG (67LR) were incorporated into hydrogels to investigate their effects on VICs. DGEA, YIGSR, and VAPG alone were insufficient to induce stable VIC adhesion. As a result, these peptides were studied in combination with 1 mM RGDS. For VICs cultured on two-dimensional hydrogel surfaces, YIGSR and VAPG down-regulated the expression of smooth muscle α-actin (myofibroblast activation marker); DGEA promoted VIC adhesion and VIC-mediated ECM deposition and inhibited the activity of alkaline phosphatase (osteogenic differentiation marker). Further, YIGSR and DGEA in combination promoted ECM deposition while inhibiting both myofibroblastic and osteogenic differentiation. However, VICs behaved differently to adhesive ligands when cultured within three-dimensional hydrogels, with most VICs assuming a healthy, quiescent phenotype under all peptide conditions tested. DGEA promoted ECM deposition by VICs within hydrogels. Overall, we demonstrate that the presentation of defined peptides targeting specific adhesion receptors can be used to regulate VIC adhesion, phenotype and ECM synthesis.
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Affiliation(s)
- Yan Wu
- Department of Biomedical Engineering, Duke University, Durham, NC
27708
| | | | - Jennifer L. West
- Department of Biomedical Engineering, Duke University, Durham, NC
27708
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Liberski A, Ayad N, Wojciechowska D, Zielińska D, Struszczyk MH, Latif N, Yacoub M. Knitting for heart valve tissue engineering. Glob Cardiol Sci Pract 2016; 2016:e201631. [PMID: 29043276 PMCID: PMC5642840 DOI: 10.21542/gcsp.2016.31] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Knitting is a versatile technology which offers a large portfolio of products and solutions of interest in heart valve (HV) tissue engineering (TE). One of the main advantages of knitting is its ability to construct complex shapes and structures by precisely assembling the yarns in the desired position. With this in mind, knitting could be employed to construct a HV scaffold that closely resembles the authentic valve. This has the potential to reproduce the anisotropic structure that is characteristic of the heart valve with the yarns, in particular the 3-layered architecture of the leaflets. These yarns can provide oriented growth of cells lengthwise and consequently enable the deposition of extracellular matrix (ECM) proteins in an oriented manner. This technique, therefore, has a potential to provide a functional knitted scaffold, but to achieve that textile engineers need to gain a basic understanding of structural and mechanical aspects of the heart valve and in addition, tissue engineers must acquire the knowledge of tools and capacities that are essential in knitting technology. The aim of this review is to provide a platform to consolidate these two fields as well as to enable an efficient communication and cooperation among these two research areas.
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Affiliation(s)
- Albert Liberski
- Sidra Medical and Research Center, P.O. Box 26999, Doha, Qatar
| | - Nadia Ayad
- Mechanical Engineering and Material Science Department, Military Institute of Engineering (IME), Rio de Janeiro, RJ, Brazil
| | - Dorota Wojciechowska
- Lodz University of Technology, Faculty of Material Technologies and Textile Design, Department of Material and Commodity Sciences and Textile Metrology, ul. Zeromskiego 116, 90-924, Lodz, Poland
| | - Dorota Zielińska
- Institute of Security Technologies "Moratex" 3 M, Skłodowskiej-Curie Street 90-505 Lodz, Poland
| | - Marcin H Struszczyk
- Institute of Security Technologies "Moratex" 3 M, Skłodowskiej-Curie Street 90-505 Lodz, Poland
| | - Najma Latif
- Imperial College of Science and Technology, London, UK
| | - Magdi Yacoub
- Sidra Medical and Research Center, P.O. Box 26999, Doha, Qatar
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Ayoub S, Ferrari G, Gorman RC, Gorman JH, Schoen FJ, Sacks MS. Heart Valve Biomechanics and Underlying Mechanobiology. Compr Physiol 2016; 6:1743-1780. [PMID: 27783858 PMCID: PMC5537387 DOI: 10.1002/cphy.c150048] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Heart valves control unidirectional blood flow within the heart during the cardiac cycle. They have a remarkable ability to withstand the demanding mechanical environment of the heart, achieving lifetime durability by processes involving the ongoing remodeling of the extracellular matrix. The focus of this review is on heart valve functional physiology, with insights into the link between disease-induced alterations in valve geometry, tissue stress, and the subsequent cell mechanobiological responses and tissue remodeling. We begin with an overview of the fundamentals of heart valve physiology and the characteristics and functions of valve interstitial cells (VICs). We then provide an overview of current experimental and computational approaches that connect VIC mechanobiological response to organ- and tissue-level deformations and improve our understanding of the underlying functional physiology of heart valves. We conclude with a summary of future trends and offer an outlook for the future of heart valve mechanobiology, specifically, multiscale modeling approaches, and the potential directions and possible challenges of research development. © 2016 American Physiological Society. Compr Physiol 6:1743-1780, 2016.
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Affiliation(s)
- Salma Ayoub
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, USA
| | - Giovanni Ferrari
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, USA
| | - Robert C. Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, USA
| | - Joseph H. Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, Philadelphia, USA
| | - Frederick J. Schoen
- Department of Pathology, Brigham and Women’s Hospital, Boston, Massachusetts, USA
| | - Michael S. Sacks
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, USA
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Aggarwal A, Pouch AM, Lai E, Lesicko J, Yushkevich PA, Gorman Iii JH, Gorman RC, Sacks MS. In-vivo heterogeneous functional and residual strains in human aortic valve leaflets. J Biomech 2016; 49:2481-90. [PMID: 27207385 PMCID: PMC5028253 DOI: 10.1016/j.jbiomech.2016.04.038] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 04/30/2016] [Indexed: 12/28/2022]
Abstract
Residual and physiological functional strains in soft tissues are known to play an important role in modulating organ stress distributions. Yet, no known comprehensive information on residual strains exist, or non-invasive techniques to quantify in-vivo deformations for the aortic valve (AV) leaflets. Herein we present a completely non-invasive approach for determining heterogeneous strains - both functional and residual - in semilunar valves and apply it to normal human AV leaflets. Transesophageal 3D echocardiographic (3DE) images of the AV were acquired from open-heart transplant patients, with each AV leaflet excised after heart explant and then imaged in a flattened configuration ex-vivo. Using an established spline parameterization of both 3DE segmentations and digitized ex-vivo images (Aggarwal et al., 2014), surface strains were calculated for deformation between the ex-vivo and three in-vivo configurations: fully open, just-coapted, and fully-loaded. Results indicated that leaflet area increased by an average of 20% from the ex-vivo to in-vivo open states, with a highly heterogeneous strain field. The increase in area from open to just-coapted state was the highest at an average of 25%, while that from just-coapted to fully-loaded remained almost unaltered. Going from the ex-vivo to in-vivo mid-systole configurations, the leaflet area near the basal attachment shrank slightly, whereas the free edge expanded by ~10%. This was accompanied by a 10° -20° shear along the circumferential-radial direction. Moreover, the principal stretches aligned approximately with the circumferential and radial directions for all cases, with the highest stretch being along the radial direction. Collectively, these results indicated that even though the AV did not support any measurable pressure gradient in the just-coapted state, the leaflets were significantly pre-strained with respect to the excised state. Furthermore, the collagen fibers of the leaflet were almost fully recruited in the just-coapted state, making the leaflet very stiff with marginal deformation under full pressure. Lastly, the deformation was always higher in the radial direction and lower along the circumferential one, the latter direction made stiffer by the preferential alignment of collagen fibers. These results provide significant insight into the distribution of residual strains and the in-vivo strains encountered during valve opening and closing in AV leaflets, and will form an important component of the tool that can evaluate valve׳s functional properties in a non-invasive manner.
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Affiliation(s)
- Ankush Aggarwal
- Center for Cardiovascular Simulation Institute for Computational Engineering & Sciences Department of Biomedical Engineering The University of Texas at Austin, Austin, TX, USA; Zienkiewicz Centre for Computational Engineering Swansea University, Swansea, UK
| | - Alison M Pouch
- Gorman Cardiovascular Research Group Department of Surgery University of Pennsylvania, Philadelphia, PA, USA
| | - Eric Lai
- Gorman Cardiovascular Research Group Department of Surgery University of Pennsylvania, Philadelphia, PA, USA
| | - John Lesicko
- Center for Cardiovascular Simulation Institute for Computational Engineering & Sciences Department of Biomedical Engineering The University of Texas at Austin, Austin, TX, USA
| | - Paul A Yushkevich
- Department of Radiology University of Pennsylvania, Philadelphia, PA, USA
| | - Joseph H Gorman Iii
- Gorman Cardiovascular Research Group Department of Surgery University of Pennsylvania, Philadelphia, PA, USA
| | - Robert C Gorman
- Gorman Cardiovascular Research Group Department of Surgery University of Pennsylvania, Philadelphia, PA, USA
| | - Michael S Sacks
- Center for Cardiovascular Simulation Institute for Computational Engineering & Sciences Department of Biomedical Engineering The University of Texas at Austin, Austin, TX, USA.
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Soares JS, Feaver KR, Zhang W, Kamensky D, Aggarwal A, Sacks MS. Biomechanical Behavior of Bioprosthetic Heart Valve Heterograft Tissues: Characterization, Simulation, and Performance. Cardiovasc Eng Technol 2016; 7:309-351. [PMID: 27507280 DOI: 10.1007/s13239-016-0276-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 07/13/2016] [Indexed: 12/11/2022]
Abstract
The use of replacement heart valves continues to grow due to the increased prevalence of valvular heart disease resulting from an ageing population. Since bioprosthetic heart valves (BHVs) continue to be the preferred replacement valve, there continues to be a strong need to develop better and more reliable BHVs through and improved the general understanding of BHV failure mechanisms. The major technological hurdle for the lifespan of the BHV implant continues to be the durability of the constituent leaflet biomaterials, which if improved can lead to substantial clinical impact. In order to develop improved solutions for BHV biomaterials, it is critical to have a better understanding of the inherent biomechanical behaviors of the leaflet biomaterials, including chemical treatment technologies, the impact of repetitive mechanical loading, and the inherent failure modes. This review seeks to provide a comprehensive overview of these issues, with a focus on developing insight on the mechanisms of BHV function and failure. Additionally, this review provides a detailed summary of the computational biomechanical simulations that have been used to inform and develop a higher level of understanding of BHV tissues and their failure modes. Collectively, this information should serve as a tool not only to infer reliable and dependable prosthesis function, but also to instigate and facilitate the design of future bioprosthetic valves and clinically impact cardiology.
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Affiliation(s)
- Joao S Soares
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th Street, Stop C0200, Austin, TX, 78712-1129, USA
| | - Kristen R Feaver
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th Street, Stop C0200, Austin, TX, 78712-1129, USA
| | - Will Zhang
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th Street, Stop C0200, Austin, TX, 78712-1129, USA
| | - David Kamensky
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th Street, Stop C0200, Austin, TX, 78712-1129, USA
| | - Ankush Aggarwal
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th Street, Stop C0200, Austin, TX, 78712-1129, USA
- College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea, SA1 8EN, UK
| | - Michael S Sacks
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th Street, Stop C0200, Austin, TX, 78712-1129, USA.
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Wu Y, Puperi DS, Grande-Allen KJ, West JL. Ascorbic acid promotes extracellular matrix deposition while preserving valve interstitial cell quiescence within 3D hydrogel scaffolds. J Tissue Eng Regen Med 2015; 11:1963-1973. [PMID: 26631842 DOI: 10.1002/term.2093] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 06/25/2015] [Accepted: 09/09/2015] [Indexed: 12/27/2022]
Abstract
Current options for aortic valve replacements are non-viable and thus lack the ability to grow and remodel, which can be problematic for paediatric applications. Toward the development of living valve substitutes that can grow and remodel, porcine aortic valve interstitial cells (VICs) were isolated and encapsulated within proteolytically degradable and cell-adhesive poly(ethylene glycol) (PEG) hydrogels, in an effort to study their phenotypes and functions. The results showed that encapsulated VICs maintained high viability and proliferated within the hydrogels. The VICs actively remodelled the hydrogels via secretion of matrix metalloproteinase-2 (MMP-2) and deposition of new extracellular matrix (ECM) components, including collagens I and III. The soft hydrogels with compressive moduli of ~4.3 kPa quickly reverted VICs from an activated myofibroblastic phenotype to a quiescent, unactivated phenotype, evidenced by the loss of α-smooth muscle actin expression upon encapsulation. In an effort to promote VIC-mediated ECM production, ascorbic acid (AA) was supplemented in the medium to investigate its effects on VIC function and phenotype. AA treatment enhanced VIC spreading and proliferation, and inhibited apoptosis. AA treatment also promoted VIC-mediated ECM remodelling by increasing MMP-2 activity and depositing collagens I and III. AA treatment did not significantly influence the expression of α-smooth muscle actin (myofibroblast activation marker) and alkaline phosphatase (osteogenic differentiation marker). No calcification or nodule formation was observed within the cell-laden hydrogels, with or without AA treatment. These results suggest the potential of this system and the beneficial effect of AA in heart valve tissue engineering. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Yan Wu
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Daniel S Puperi
- Department of Bioengineering, Rice University, Houston, TX, USA
| | | | - Jennifer L West
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
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45
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Abstract
Heart disease, including valve pathologies, is the leading cause of death worldwide. Despite the progress made thanks to improving transplantation techniques, a perfect valve substitute has not yet been developed: once a diseased valve is replaced with current technologies, the newly implanted valve still needs to be changed some time in the future. This situation is particularly dramatic in the case of children and young adults, because of the necessity of valve growth during the patient's life. Our review focuses on the current status of heart valve (HV) therapy and the challenges that must be solved in the development of new approaches based on tissue engineering. Scientists and physicians have proposed tissue-engineered heart valves (TEHVs) as the most promising solution for HV replacement, especially given that they can help to avoid thrombosis, structural deterioration and xenoinfections. Lastly, TEHVs might also serve as a model for studying human valve development and pathologies.
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46
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Alavi SH, Sinha A, Steward E, Milliken JC, Kheradvar A. Load-dependent extracellular matrix organization in atrioventricular heart valves: differences and similarities. Am J Physiol Heart Circ Physiol 2015; 309:H276-84. [DOI: 10.1152/ajpheart.00164.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 05/17/2015] [Indexed: 12/31/2022]
Abstract
The extracellular matrix of the atrioventricular (AV) valves' leaflets has a key role in the ability of these valves to properly remodel in response to constantly varying physiological loads. While the loading on mitral and tricuspid valves is significantly different, no information is available on how collagen fibers change their orientation in response to these loads. This study delineates the effect of physiological loading on AV valves' leaflets microstructures using Second Harmonic Generation (SHG) microscopy. Fresh natural porcine tricuspid and mitral valves' leaflets ( n = 12/valve type) were cut and prepared for the experiments. Histology and immunohistochemistry were performed to compare the microstructural differences between the valves. The specimens were imaged live during the relaxed, loading, and unloading phases using SHG microscopy. The images were analyzed with Fourier decomposition to mathematically seek changes in collagen fiber orientation. Despite the similarities in both AV valves as seen in the histology and immunohistochemistry data, the microstructural arrangement, especially the collagen fiber distribution and orientation in the stress-free condition, were found to be different. Uniaxial loading was dependent on the arrangement of the fibers in their relaxed mode, which led the fibers to reorient in-line with the load throughout the depth of the mitral leaflet but only to reorient in-line with the load in deeper layers of the tricuspid leaflet. Biaxial loading arranged the fibers in between the two principal axes of the stresses independently from their relaxed states. Unlike previous findings, this study concludes that the AV valves' three-dimensional extracellular fiber arrangement is significantly different in their stress-free and uniaxially loaded states; however, fiber rearrangement in response to the biaxial loading remains similar.
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Affiliation(s)
- S. Hamed Alavi
- The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, Irvine, California
- Department Biomedical Engineering, University of California, Irvine, Irvine, California; and
| | - Aditi Sinha
- The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, Irvine, California
- Department Biomedical Engineering, University of California, Irvine, Irvine, California; and
| | - Earl Steward
- Division of Cardiothoracic Surgery, University of California, Irvine, Irvine, California
| | - Jeffrey C. Milliken
- Division of Cardiothoracic Surgery, University of California, Irvine, Irvine, California
| | - Arash Kheradvar
- The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, Irvine, California
- Department Biomedical Engineering, University of California, Irvine, Irvine, California; and
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Coupled Simulation of Heart Valves: Applications to Clinical Practice. Ann Biomed Eng 2015; 43:1626-39. [PMID: 26101029 DOI: 10.1007/s10439-015-1348-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 05/26/2015] [Indexed: 12/16/2022]
Abstract
The last few decades have seen great advances in the understanding of heart valves, and consequently, in the development of novel treatment modalities and surgical procedures for valves afflicted by disease. This is due in part to the profound advancements in computing technology and noninvasive medical imaging techniques that have made it possible to numerically model the complex heart valve systems characterized by distinct features at different length scales and various interacting processes. In this article, we highlight the importance of explicitly coupling these multiple scales and diverse processes to accurately simulate the true behavior of the heart valves, in health and disease. We examine some of the computational modeling studies that have a direct consequence on clinical practice.
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48
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Bowler MA, Merryman WD. In vitro models of aortic valve calcification: solidifying a system. Cardiovasc Pathol 2015; 24:1-10. [PMID: 25249188 PMCID: PMC4268061 DOI: 10.1016/j.carpath.2014.08.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 07/21/2014] [Accepted: 08/07/2014] [Indexed: 12/21/2022] Open
Abstract
Calcific aortic valve disease (CAVD) affects 25% of people over 65, and the late-stage stenotic state can only be treated with total valve replacement, requiring 85,000 surgeries annually in the US alone (University of Maryland Medical Center, 2013, http://umm.edu/programs/services/heart-center-programs/cardiothoracic-surgery/valve-surgery/facts). As CAVD is an age-related disease, many of the affected patients are unable to undergo the open-chest surgery that is its only current cure. This challenge motivates the elucidation of the mechanisms involved in calcification, with the eventual goal of alternative preventative and therapeutic strategies. There is no sufficient animal model of CAVD, so we turn to potential in vitro models. In general, in vitro models have the advantages of shortened experiment time and better control over multiple variables compared to in vivo models. As with all models, the hypothesis being tested dictates the most important characteristics of the in vivo physiology to recapitulate. Here, we collate the relevant pieces of designing and evaluating aortic valve calcification so that investigators can more effectively draw significant conclusions from their results.
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Affiliation(s)
- Meghan A Bowler
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37212
| | - W David Merryman
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37212.
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Tseng H, Puperi DS, Kim EJ, Ayoub S, Shah JV, Cuchiara ML, West JL, Grande-Allen KJ. Anisotropic poly(ethylene glycol)/polycaprolactone hydrogel-fiber composites for heart valve tissue engineering. Tissue Eng Part A 2014; 20:2634-45. [PMID: 24712446 PMCID: PMC4195534 DOI: 10.1089/ten.tea.2013.0397] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 03/19/2014] [Indexed: 11/12/2022] Open
Abstract
The recapitulation of the material properties and structure of the native aortic valve leaflet, specifically its anisotropy and laminate structure, is a major design goal for scaffolds for heart valve tissue engineering. Poly(ethylene glycol) (PEG) hydrogels are attractive scaffolds for this purpose as they are biocompatible, can be modified for their mechanical and biofunctional properties, and can be laminated. This study investigated augmenting PEG hydrogels with polycaprolactone (PCL) as an analog to the fibrosa to improve strength and introduce anisotropic mechanical behavior. However, due to its hydrophobicity, PCL must be modified prior to embedding within PEG hydrogels. In this study, PCL was electrospun (ePCL) and modified in three different ways, by protein adsorption (pPCL), alkali digestion (hPCL), and acrylation (aPCL). Modified PCL of all types maintained the anisotropic elastic moduli and yield strain of unmodified anisotropic ePCL. Composites of PEG and PCL (PPCs) maintained anisotropic elastic moduli, but aPCL and pPCL had isotropic yield strains. Overall, PPCs of all modifications had elastic moduli of 3.79±0.90 MPa and 0.46±0.21 MPa in the parallel and perpendicular directions, respectively. Valvular interstitial cells seeded atop anisotropic aPCL displayed an actin distribution aligned in the direction of the underlying fibers. The resulting scaffold combines the biocompatibility and tunable fabrication of PEG with the strength and anisotropy of ePCL to form a foundation for future engineered valve scaffolds.
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Affiliation(s)
- Hubert Tseng
- Department of Bioengineering, Rice University, Houston, Texas
| | | | - Eric J. Kim
- Department of Bioengineering, Rice University, Houston, Texas
| | - Salma Ayoub
- Department of Bioengineering, Rice University, Houston, Texas
| | - Jay V. Shah
- Department of Bioengineering, Rice University, Houston, Texas
| | - Maude L. Cuchiara
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Jennifer L. West
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
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Mahler GJ, Frendl CM, Cao Q, Butcher JT. Effects of shear stress pattern and magnitude on mesenchymal transformation and invasion of aortic valve endothelial cells. Biotechnol Bioeng 2014; 111:2326-37. [PMID: 24898772 DOI: 10.1002/bit.25291] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/18/2014] [Accepted: 05/07/2014] [Indexed: 01/23/2023]
Abstract
Understanding the role of mechanical forces on cell behavior is critical for tissue engineering, regenerative medicine, and disease initiation studies. Current hemodynamic bioreactors are largely limited to 2D substrates or the application of general flow conditions at a tissue level, which eliminates the investigation of some essential physiological and pathological responses. One example is the mesenchymal transformation of endothelial cells in response to shear stress. Endothelial to mesenchymal transformation (EndMT) is a valve morphogenic mechanism associated with aortic valve disease initiation. The aortic valve experiences oscillatory shear on the disease-susceptible fibrosa, and the role of hemodynamics on adult EndMT is unknown. The goal of this work was to develop and characterize a microfluidic bioreactor that applies physiologically relevant laminar or oscillatory shear stresses to endothelial cells and permits the quantitative analysis of 3D cell-extracellular matrix (ECM) interactions. In this study, porcine aortic valve endothelial cells were seeded onto 3D collagen I gels and exposed to different magnitudes of steady or oscillatory shear stress for 48 h. Cells elongated and aligned perpendicular to laminar, but not oscillatory shear. Low steady shear stress (2 dyne/cm(2) ) and oscillatory shear stress upregulated EndMT (ACTA2, Snail, TGFB1) and inflammation (ICAM1, NFKB1) related gene expression, EndMT-related (αSMA) protein expression, and matrix invasion when compared with static controls or cells exposed to high steady shear (10 and 20 dyne/cm(2) ). Our system enables direct testing of the role of shear stress on endothelial cell mesenchymal transformation in a dynamic, 3D environment and shows that hemodynamics regulate EndMT in adult valve endothelial cells.
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Affiliation(s)
- Gretchen J Mahler
- Department of Biomedical Engineering, Cornell University, Ithaca, New York; Department of Bioengineering, Binghamton University, Binghamton, New York
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