1
|
Petrovic M, Kahle ER, Han L, Marcolongo MS. Biomimetic proteoglycans as a tool to engineer the structure and mechanics of porcine bioprosthetic heart valves. J Biomed Mater Res B Appl Biomater 2024; 112:e35336. [PMID: 37818847 PMCID: PMC11055403 DOI: 10.1002/jbm.b.35336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 08/21/2023] [Accepted: 09/18/2023] [Indexed: 10/13/2023]
Abstract
The utility of bioprosthetic heart valves (BHVs) is limited to certain patient populations because of their poor durability compared to mechanical prosthetic valves. Histological analysis of failed porcine BHVs suggests that degeneration of the tissue extracellular matrix (ECM), specifically the loss of proteoglycans and their glycosaminoglycans (GAGs), may lead to impaired mechanical performance, resulting in nucleation and propagation of tears and ultimately failure of the prosthetic. Several strategies have been proposed to address this deterioration, including novel chemical fixatives to stabilize ECM constituents and incorporation of small molecule inhibitors of catabolic enzymes implicated in the degeneration of the BHV ECM. Here, biomimetic proteoglycans (BPGs) were introduced into porcine aortic valves ex vivo and were shown to distribute throughout the valve leaflets. Incorporation of BPGs into the heart valve leaflet increased tissue overall GAG content. The presence of BPGs also significantly increased the micromodulus of the spongiosa layer within the BHV without compromising the chemical fixation process used to sterilize and strengthen the tissue prior to implantation. These findings suggest that a targeted approach for molecularly engineering valve leaflet ECM through the use of BPGs may be a viable way to improve the mechanical behavior and potential durability of BHVs.
Collapse
Affiliation(s)
- Mark Petrovic
- Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania, USA
- Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Elizabeth R. Kahle
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania, USA
| | - Lin Han
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania, USA
| | - Michele S. Marcolongo
- Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania, USA
- Department of Mechanical Engineering, Villanova University, Villanova, Pennsylvania, USA
| |
Collapse
|
2
|
Hu M, Shi S, Peng X, Pu X, Yu X. A synergistic strategy of dual-crosslinking and loading intelligent nanogels for enhancing anti-coagulation, pro-endothelialization and anti-calcification properties in bioprosthetic heart valves. Acta Biomater 2023; 171:466-481. [PMID: 37793601 DOI: 10.1016/j.actbio.2023.09.045] [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: 05/04/2023] [Revised: 09/07/2023] [Accepted: 09/26/2023] [Indexed: 10/06/2023]
Abstract
Currently, glutaraldehyde (GA)-crosslinked bioprosthetic heart valves (BHVs) still do not guarantee good biocompatibility and long-term effective durability for clinical application due to their subacute thrombus, inflammation, calcification, tearing and limited durability. In this study, double-modified xanthan gum (oxidized/vinylated xanthan gum (O2CXG)) was acquired from xanthan gum for subsequent double crosslinking and modification platform construction. Sulfonic acid groups with anticoagulant properties were also introduced through the free radical polymerization of vinyl sulfonate (VS) and vinyl on O2CXG. Taking advantage of the drug-loading function of xanthan gum, the treated pericardium was further loaded with inflammation-triggered dual drug-loaded nanogel (heparin (Hep) and atorvastatin (Ator)). Mechanical properties of O2CXG-crosslinked porcine pericardium (O2CXG-PP) were significantly improved via the first network formed by Schiff base bonds and the second C-C bonds network. Due to the presence of sulfonic acid groups as well as the dual drug release from nanogels under the stimulation of H2O2, the hemocompatibility, anti-inflammatory, pro-endothelialization and anti-calcification properties of the crosslinked pericardium modified with nanogels loaded with Hep and Ator (O2CXG+VS+(Hep+Ator) nanogel-PP) was significantly better than that of GA-crosslinked PP (GA-PP). The collaborative strategy of double crosslinking and sequential release of anticoagulant/endothelium-promoting drugs triggered by inflammation could effectively meet the requirement of enhanced multiple performance and long-term durability of bioprosthetic heart valves and provide a valuable pattern for multi-functionalization of blood contacting materials. STATEMENT OF SIGNIFICANCE: Currently, glutaraldehyde-crosslinked bioprosthetic heart valves (BHVs) are subject to subacute thrombus, inflammation, calcification and tearing, which would not guarantee good biocompatibility and long-term effective durability. We developed a cooperative strategy of double crosslinking and surface modification in which double-modified xanthan gum plays a cornerstone. The mechanical properties of this BHV were significantly improved via the first network formed by Schiff base bonds and the second C-C bonds network. Inflammation-triggered combination delivery of heparin and atorvastatin has been demonstrated to enhance anticoagulation, anti-inflammatory and pro-endothelialization of BHVs by utilizing local inflammatory response. The collaborative strategy could effectively meet the requirement of enhanced multiple performance and long-term durability of BHVs and provide a valuable pattern for the multi-functionalization of blood-contacting materials.
Collapse
Affiliation(s)
- Mengyue Hu
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, PR China
| | - Shubin Shi
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, PR China
| | - Xu Peng
- Experimental and Research Animal Institute, Sichuan University, Chengdu 610065, PR China
| | - Xinyun Pu
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, PR China
| | - Xixun Yu
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, PR China.
| |
Collapse
|
3
|
Aggarwal A, Hudson LT, Laurence DW, Lee CH, Pant S. A Bayesian constitutive model selection framework for biaxial mechanical testing of planar soft tissues: Application to porcine aortic valves. J Mech Behav Biomed Mater 2023; 138:105657. [PMID: 36634438 PMCID: PMC10226148 DOI: 10.1016/j.jmbbm.2023.105657] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/20/2022] [Accepted: 01/03/2023] [Indexed: 01/06/2023]
Abstract
A variety of constitutive models have been developed for soft tissue mechanics. However, there is no established criterion to select a suitable model for a specific application. Although the model that best fits the experimental data can be deemed the most suitable model, this practice often can be insufficient given the inter-sample variability of experimental observations. Herein, we present a Bayesian approach to calculate the relative probabilities of constitutive models based on biaxial mechanical testing of tissue samples. Forty-six samples of porcine aortic valve tissue were tested using a biaxial stretching setup. For each sample, seven ratios of stresses along and perpendicular to the fiber direction were applied. The probabilities of eight invariant-based constitutive models were calculated based on the experimental data using the proposed model selection framework. The calculated probabilities showed that, out of the considered models and based on the information available through the utilized experimental dataset, the May-Newman model was the most probable model for the porcine aortic valve data. When the samples were further grouped into different cusp types, the May-Newman model remained the most probable for the left- and right-coronary cusps, whereas for non-coronary cusps two models were found to be equally probable: the Lee-Sacks model and the May-Newman model. This difference between cusp types was found to be associated with the first principal component analysis (PCA) mode, where this mode's amplitudes of the non-coronary and right-coronary cusps were found to be significantly different. Our results show that a PCA-based statistical model can capture significant variations in the mechanical properties of soft tissues. The presented framework is applicable to other tissue types, and has the potential to provide a structured and rational way of making simulations population-based.
Collapse
Affiliation(s)
- Ankush Aggarwal
- Glasgow Computational Engineering Centre, James Watt School of Engineering, University of Glasgow, Glasgow, G12 8LT, Scotland, United Kingdom.
| | - Luke T Hudson
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, 73019, OK, United States of America
| | - Devin W Laurence
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, 73019, OK, United States of America
| | - Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, 73019, OK, United States of America
| | - Sanjay Pant
- Faculty of Science and Engineering, Swansea University, Swansea, SA1 8EN, Wales, United Kingdom
| |
Collapse
|
4
|
Readioff R, Geraghty B, Kharaz YA, Elsheikh A, Comerford E. Proteoglycans play a role in the viscoelastic behaviour of the canine cranial cruciate ligament. Front Bioeng Biotechnol 2022; 10:984224. [PMID: 36457857 PMCID: PMC9705345 DOI: 10.3389/fbioe.2022.984224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 10/31/2022] [Indexed: 07/01/2024] Open
Abstract
Proteoglycans (PGs) are minor extracellular matrix proteins, and their contributions to the mechanobiology of complex ligaments such as the cranial cruciate ligament (CCL) have not been determined to date. The CCLs are highly susceptible to injuries, and their extracellular matrix comprises higher PGs content than the other major knee ligaments. Hence these characteristics make CCLs an ideal specimen to use as a model in this study. This study addressed the hypothesis that PGs play a vital role in CCL mechanobiology by determining the biomechanical behaviour at low strain rates before and after altering PGs content. For the first time, this study qualitatively investigated the contribution of PGs to key viscoelastic characteristics, including strain rate dependency, hysteresis, creep and stress relaxation, in canine CCLs. Femur-CCL-tibia specimens (n = 6 pairs) were harvested from canine knee joints and categorised into a control group, where PGs were not depleted, and a treated group, where PGs were depleted. Specimens were preconditioned and cyclically loaded to 9.9 N at 0.1, 1 and 10%/min strain rates, followed by creep and stress relaxation tests. Low tensile loads were applied to focus on the toe-region of the stress-strain curves where the non-collagenous extracellular matrix components take significant effect. Biochemical assays were performed on the CCLs to determine PGs and water content. The PG content was ∼19% less in the treated group than in the control group. The qualitative study showed that the stress-strain curves in the treated group were strain rate dependent, similar to the control group. The CCLs in the treated group showed stiffer characteristics than the control group. Hysteresis, creep characteristics (creep strain, creep rate and creep compliance), and stress relaxation values were reduced in the treated group compared to the control group. This study suggests that altering PGs content changes the microstructural organisation of the CCLs, including water molecule contents which can lead to changes in CCL viscoelasticity. The change in mechanical properties of the CCLs may predispose to injury and lead to knee joint osteoarthritis. Future studies should focus on quantitatively identifying the effect of PG on the mechanics of intact knee ligaments across broader demography.
Collapse
Affiliation(s)
- Rosti Readioff
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, Liverpool, United Kingdom
- Faculty of Engineering, School of Mechanical Engineering, Institute of Medical and Biological Engineering, University of Leeds, Leeds, United Kingdom
- School of Dentistry, University of Liverpool, Liverpool, United Kingdom
- Department of Mechanical Engineering, University of Bath, Bath, United Kingdom
| | - Brendan Geraghty
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Yalda A. Kharaz
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
- Medical Research Council Versus Arthritis Centre for Integrated Research Into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, United Kingdom
| | - Ahmed Elsheikh
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, Liverpool, United Kingdom
- Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, China
- NIHR Moorfields BRC, UCL Institute of Ophthalmology, London, United Kingdom
| | - Eithne Comerford
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
- Medical Research Council Versus Arthritis Centre for Integrated Research Into Musculoskeletal Ageing (CIMA), University of Liverpool, Liverpool, United Kingdom
- School of Veterinary Science, University of Liverpool, Neston, United Kingdom
| |
Collapse
|
5
|
Hu M, Peng X, Shi S, Wan C, Cheng C, Lei N, Yu X. Sulfonated, oxidized pectin-based double crosslinked bioprosthetic valve leaflets for synergistically enhancing hemocompatibility and cytocompatibility and reducing calcification. J Mater Chem B 2022; 10:8218-8234. [PMID: 36173240 DOI: 10.1039/d2tb01704k] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Clinically frequently-used glutaraldehyde (GA)-crosslinked bioprosthetic valve leaflets (BVLs) are still curbed by acute thrombosis, malignant immunoreaction, calcification, and poor durability. In this study, an anticoagulant heparin-like biomacromolecule, sulfonated, oxidized pectin (SAP) with a dialdehyde structure was first obtained by modifying citrus pectin with sulfonation of 3-amino-1-propane sulfonic acid and then oxidating with periodate. Notably, a novel crosslinking approach was established by doubly crosslinking BVLs with SAP and the nature-derived crosslinking agent quercetin (Que), which play a synergistic role in both crosslinking and bioactivity. The double crosslinked BVLs also presented enhanced mechanical properties and enzymatic degradation resistance owing to the double crosslinking networks formed via CN bonds and hydrogen bonds, respectively, and good HUVEC-cytocompatibility. The in vitro and ex vivo assay manifested that the double-crosslinked BVLs had excellent anticoagulant and antithrombotic properties, owing to the introduction of SAP. The subcutaneous implantation also demonstrated that the obtained BVLs showed a reduced inflammatory response and great resistance to calcification, which is attributed to quercetin with multiple physiological activities and depletion of aldehyde groups by hydroxyl aldehyde reaction. With excellent stability, hemocompatibility, anti-inflammatory, anti-calcification, and pro-endothelialization properties, the obtained double-crosslinked BVLs, SAP + Que-PP, would have great potential to substitute the current clinical GA-crosslinked BVLs.
Collapse
Affiliation(s)
- Mengyue Hu
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, P. R. China.
| | - Xu Peng
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, P. R. China. .,Experimental and Research Animal Institute, Sichuan University, Chengdu 610065, P. R. China
| | - Shubin Shi
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, P. R. China.
| | - Chang Wan
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, P. R. China.
| | - Can Cheng
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, P. R. China.
| | - Ningning Lei
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, P. R. China.
| | - Xixun Yu
- College of Polymer Science and Engineering, Sichuan University, Chengdu 610065, P. R. China.
| |
Collapse
|
6
|
Nellinger S, Mrsic I, Keller S, Heine S, Southan A, Bach M, Volz A, Chassé T, Kluger PJ. Cell‐derived and enzyme‐based decellularized extracellular matrix exhibit compositional and structural differences that are relevant for its use as a biomaterial. Biotechnol Bioeng 2022; 119:1142-1156. [DOI: 10.1002/bit.28047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 01/01/2022] [Accepted: 01/19/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Svenja Nellinger
- Reutlingen Research Institute Alteburgstr. 150 72762 Reutlingen Germany
| | - Ivana Mrsic
- Institute of Physical and Theoretical Chemistry, University of Tuebingen Auf der Morgenstelle 18 72076 Tuebingen Germany
| | - Silke Keller
- 3R‐Center for In Vitro Models and Alternatives to Animal Testing, Eberhard Karls University Tübingen Österbergstr. 3 72074 Tübingen Germany
- Department for Microphysiological Systems Institute of Biomedical Engineering, Faculty of Medicine of the Eberhard Karls University Tübingen Österbergstr. 3 72074 Tübingen Germany
| | - Simon Heine
- Reutlingen Research Institute Alteburgstr. 150 72762 Reutlingen Germany
| | - Alexander Southan
- Institute of Interfacial Process Engineering and Plasma Technology, University of Stuttgart Nobelstr. 12 70569 Stuttgart Germany
| | - Monika Bach
- Core Facility Hohenheim, University of Hohenheim Emil‐Wolff‐Str. 12 70599 Stuttgart Germany
| | - Ann‐Cathrin Volz
- Reutlingen Research Institute Alteburgstr. 150 72762 Reutlingen Germany
| | - Thomas Chassé
- Institute of Physical and Theoretical Chemistry, University of Tuebingen Auf der Morgenstelle 18 72076 Tuebingen Germany
| | - Petra J. Kluger
- School of Applied Chemistry, Reutlingen University Alteburgstr. 150 72762 Reutlingen Germany
| |
Collapse
|
7
|
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.
Collapse
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.
| |
Collapse
|
8
|
Hatami-Marbini H, Pachenari M. Tensile Viscoelastic Properties of the Sclera after Glycosaminoglycan Depletion. Curr Eye Res 2021; 46:1299-1308. [PMID: 34325593 DOI: 10.1080/02713683.2021.1874026] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE Fibrillar collagen network and glycosaminoglycans (GAGs) are the primary components of extracellular matrix (ECM) of the sclera. The main goal of this study was to investigate the possible structural roles of GAGs in the scleral tensile properties as a function of preconditioning and displacement rate. METHODS Four-step uniaxial stress-relaxation tests were used for characterizing the viscoelastic tensile response of the posterior porcine sclera with and without enzymatic GAG removal. The scleral strips were divided into different groups based on the displacement rate and the presence or absence of a preconditioning step in the loading protocol. The groups were (1) displacement rate of 0.2 mm/min without preconditioning, (2) displacement rate of 1 mm/min without preconditioning, (3) displacement rate of 0.2 mm/min with preconditioning, and (4) displacement rate of 1 mm/min with preconditioning. The peak stress, equilibrium stress, and the equilibrium elastic modulus were calculated for all specimens and compared against each other. RESULTS Increasing the displacement rate from 0.2 mm/min to 1.0 mm/min was found to cause an insignificant change in the equilibrium stress and equilibrium elastic modulus of porcine scleral strips. Removal of GAGs resulted in an overall stiffer tensile behavior independent of the displacement rate in samples that were not preconditioned (P < .05). The behavior of preconditioned samples with and without GAG removal was not significantly different from each other. CONCLUSIONS The experimental measurements of the present study showed that GAGs play an important role in the mechanical properties of the posterior porcine sclera. Furthermore, using a preconditioning step in the uniaxial testing protocol resulted in not being able to identify any significant difference in the tensile behavior of GAG depleted and normal scleral strips.
Collapse
Affiliation(s)
- Hamed Hatami-Marbini
- Computational Biomechanics Research Laboratory, Mechanical and Industrial Engineering Department, University of Illinois at Chicago, Chicago, IL, USA
| | - Mohammad Pachenari
- Computational Biomechanics Research Laboratory, Mechanical and Industrial Engineering Department, University of Illinois at Chicago, Chicago, IL, USA
| |
Collapse
|
9
|
Nazir R, Bruyneel A, Carr C, Czernuszka J. Mechanical and Degradation Properties of Hybrid Scaffolds for Tissue Engineered Heart Valve (TEHV). J Funct Biomater 2021; 12:20. [PMID: 33803209 PMCID: PMC8006234 DOI: 10.3390/jfb12010020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 02/26/2021] [Accepted: 03/03/2021] [Indexed: 01/06/2023] Open
Abstract
In addition to biocompatibility, an ideal scaffold for the regeneration of valvular tissue should also replicate the natural heart valve extracellular matrix (ECM) in terms of biomechanical properties and structural stability. In our previous paper, we demonstrated the development of collagen type I and hyaluronic acid (HA)-based scaffolds with interlaced microstructure. Such hybrid scaffolds were found to be compatible with cardiosphere-derived cells (CDCs) to potentially regenerate the diseased aortic heart valve. This paper focused on the quantification of the effect of crosslinking density on the mechanical properties under dry and wet conditions as well as degradation resistance. Elastic moduli increased with increasing crosslinking densities, in the dry and wet state, for parent networks, whereas those of interlaced scaffolds were higher than either network alone. Compressive and storage moduli ranged from 35 ± 5 to 95 ± 5 kPa and 16 ± 2 kPa to 113 ± 6 kPa, respectively, in the dry state. Storage moduli, in the dry state, matched and exceeded those of human aortic valve leaflets (HAVL). Similarly, degradation resistance increased with increasing the crosslinking densities for collagen-only and HA-only scaffolds. Interlaced scaffolds showed partial degradation in the presence of either collagenase or hyaluronidase as compared to when exposed to both enzymes together. These results agree with our previous findings that interlaced scaffolds were composed of independent collagen and HA networks without crosslinking between them. Thus, collagen/HA interlaced scaffolds have the potential to fill in the niche for designing an ideal tissue engineered heart valve (TEHV).
Collapse
Affiliation(s)
- Rabia Nazir
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK;
- Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS University Islamabad (CUI), Lahore Campus, Lahore 54000, Pakistan
| | - Arne Bruyneel
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK; (A.B.); (C.C.)
| | - Carolyn Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK; (A.B.); (C.C.)
| | - Jan Czernuszka
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK;
| |
Collapse
|
10
|
Bender JM, Adams WR, Mahadevan-Jansen A, Merryman WD, Bersi MR. Radiofrequency ablation alters the microstructural organization of healthy and enzymatically digested porcine mitral valves. EXPERIMENTAL MECHANICS 2021; 61:235-251. [PMID: 33776074 PMCID: PMC7992362 DOI: 10.1007/s11340-020-00662-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 08/20/2020] [Accepted: 08/25/2020] [Indexed: 05/12/2023]
Abstract
BACKGROUND Myxomatous mitral valve degeneration is a common cause of mitral regurgitation and is often associated with mitral valve prolapse. With no known targets to pharmacologically treat mitral valve prolapse, surgery is often the only treatment option. Recently, radiofrequency ablation has been proposed as a percutaneous alternative to surgical resection for the reduction of mitral valve leaflet area. OBJECTIVE Using an in vitro model of porcine mitral valve anterior leaflet enlargement following enzymatic digestion, we sought to investigate mechanisms by which radiofrequency ablation alters the geometry, microstructural organization, and mechanical properties of healthy and digested leaflets. METHODS Paired measurements before and after ablation revealed the impact of radiofrequency ablation on leaflet properties. Multiphoton imaging was used to characterize changes in the structure and organization of the valvular extracellular matrix; planar biaxial mechanical testing and constitutive modeling were used to estimate mechanical properties of healthy and digested leaflets. RESULTS Enzymatic digestion increased leaflet area and thickness to a similar extent as clinical mitral valve disease. Radiofrequency ablation altered extracellular matrix alignment and reduced the area of digested leaflets to that of control. Additionally, enzymatic digestion resulted in fiber alignment and reorientation toward the radial direction, causing increased forces during ablation and a structural stiffening which was improved by radiofrequency ablation. CONCLUSION Radiofrequency ablation induces radial extracellular matrix alignment and effectively reduces the area of enlarged mitral valve leaflets. Hence, this technique may be a therapeutic approach for myxomatous mitral valve disease and is thus an avenue for future study.
Collapse
Affiliation(s)
- J M Bender
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - W R Adams
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - A Mahadevan-Jansen
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - W D Merryman
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - M R Bersi
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| |
Collapse
|
11
|
Ma H, Macdougall LJ, GonzalezRodriguez A, Schroeder ME, Batan D, Weiss RM, Anseth KS. Calcium Signaling Regulates Valvular Interstitial Cell Alignment and Myofibroblast Activation in Fast-Relaxing Boronate Hydrogels. Macromol Biosci 2020; 20:e2000268. [PMID: 32924320 PMCID: PMC7773027 DOI: 10.1002/mabi.202000268] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Indexed: 12/28/2022]
Abstract
The role viscoelasticity in fibrotic disease progression is an emerging area of interest. Here, a fast-relaxing hydrogel system is exploited to investigate potential crosstalk between calcium signaling and mechanotransduction. Poly(ethylene glycol) (PEG) hydrogels containing boronate and triazole crosslinkers are synthesized, with varying ratios of boronate to triazole crosslinks to systematically vary the extent of stress relaxation. Valvular interstitial cells (VICs) encapsulated in hydrogels with the highest levels of stress relaxation (90%) exhibit a spread morphology by day 1 and are highly aligned (80 ± 2%) by day 5. Key myofibroblast markers, including α-smooth muscle actin (αSMA) and collagen 1a1 (COL1A1), are significantly elevated. VIC myofibroblast activation decreases by 42 ± 18% through inhibition of mechanotransduction, independently of VIC morphology and alignment. Calcium signaling through a transient receptor potential vanilloid 4 (TRPV4) is found to regulate VIC spreading, alignment, and activation in a time dependent manner. Inhibition of calcium signaling at early time points results in disturbed cell alignment, decreased mechanotransduction, and diminished activation, while inhibition at later time points only causes partially reduced myofibroblast activation. These results suggest a potential crosstalk mechanism, where calcium signaling acts upstream of mechanosensing and can regulate VIC myofibroblast activation independently of mechanotransduction.
Collapse
Affiliation(s)
- Hao Ma
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, 80303, USA
- The BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, 80303, USA
| | - Laura J Macdougall
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, 80303, USA
- The BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, 80303, USA
| | - Andrea GonzalezRodriguez
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, 80303, USA
- The BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, 80303, USA
| | - Megan E Schroeder
- The BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, 80303, USA
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, CO, 80303, USA
| | - Dilara Batan
- The BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, 80303, USA
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, 80303, USA
| | - Robert M Weiss
- Division of Cardiovascular Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Kristi S Anseth
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, 80303, USA
- The BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, 80303, USA
| |
Collapse
|
12
|
Mechanical characterization and identification of material parameters of porcine aortic valve leaflets. J Mech Behav Biomed Mater 2020; 112:104036. [PMID: 32882679 DOI: 10.1016/j.jmbbm.2020.104036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 03/16/2020] [Accepted: 08/10/2020] [Indexed: 11/22/2022]
Abstract
The ideal artificial heart valve does not exist yet. Understanding of mechanical and structural properties of natural tissues is necessary to improve the design of biomimetic aortic valve. Besides these properties are needed for the finite element modeling as input parameters. In this study we propose a new method combining biaxial tests and digital image correlation. These tests are carried out on porcine aortic valves. In this work, we use a modified version of the HGO (Holzapfel-Gasser-Ogden) model which is classically used for hyper-elastic and anisotropic soft tissues. This model can include fiber orientation. The identification of HGO model parameters can be determined using experimental data and two different protocols. One protocol is based on the identification of collagen fibers orientation as well as the mechanical parameters. The second one, is based on a complementary experiment to determine orientation (confocal laser scanning microscope). Both lead to determine different sets of material parameters. We show that the model is more likely to reproduce the actual mechanical behavior of the heart valves in the second case and that a minimum of three different loading conditions for the biaxial tensile tests is required to obtain a relevant set of parameters.
Collapse
|
13
|
Burkert J, Kochová P, Tonar Z, Cimrman R, Blassová T, Jashari R, Fiala R, Špatenka J. The time has come to extend the expiration limit of cryopreserved allograft heart valves. Cell Tissue Bank 2020; 22:161-184. [PMID: 32583302 DOI: 10.1007/s10561-020-09843-2] [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: 03/30/2020] [Accepted: 06/13/2020] [Indexed: 12/12/2022]
Abstract
Despite the wide choice of commercial heart valve prostheses, cryopreserved semilunar allograft heart valves (C-AHV) are required, and successfully transplanted in selected groups of patients. The expiration limit (EL) criteria have not been defined yet. Most Tissue Establishments (TE) use the EL of 5 years. From physiological, functional, and surgical point of view, the morphology and mechanical properties of aortic and pulmonary roots represent basic features limiting the EL of C-AHV. The aim of this work was to review methods of AHV tissue structural analysis and mechanical testing from the perspective of suitability for EL validation studies. Microscopic structure analysis of great arterial wall and semilunar leaflets tissue should clearly demonstrate cells as well as the extracellular matrix components by highly reproducible and specific histological staining procedures. Quantitative morphometry using stereological grids has proved to be effective, as the exact statistics was feasible. From mechanical testing methods, tensile test was the most suitable. Young's moduli of elasticity, ultimate stress and strain were shown to represent most important AHV tissue mechanical characteristics, suitable for exact statistical analysis. C-AHV are prepared by many different protocols, so as each TE has to work out own EL for C-AHV.
Collapse
Affiliation(s)
- Jan Burkert
- Department of Transplantation and Tissue Banking, Czech National Allograft Heart Valve Bank, Department of Cardiovascular Surgery, Motol University Hospital, and Second Faculty of Medicine Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic
| | - Petra Kochová
- Department of Transplantation and Tissue Banking, Czech National Allograft Heart Valve Bank, Department of Cardiovascular Surgery, Motol University Hospital, and Second Faculty of Medicine Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic. .,NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Technická 8, Pilsen, Czech Republic.
| | - Zbyněk Tonar
- NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Technická 8, Pilsen, Czech Republic.,Department of Histology and Embryology, Biomedical Centre, Faculty of Medicine in Pilsen, Charles University in Prague, Karlovarská 48, 301 66, Pilsen, Czech Republic
| | - Robert Cimrman
- NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Technická 8, Pilsen, Czech Republic
| | - Tereza Blassová
- Department of Histology and Embryology, Biomedical Centre, Faculty of Medicine in Pilsen, Charles University in Prague, Karlovarská 48, 301 66, Pilsen, Czech Republic
| | - Ramadan Jashari
- European Homograft Bank, Saint-Jean Clinic, Rue du Meridien 100, 1210, Brussels, Belgium
| | - Radovan Fiala
- Department of Transplantation and Tissue Banking, Czech National Allograft Heart Valve Bank, Department of Cardiovascular Surgery, Motol University Hospital, and Second Faculty of Medicine Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic
| | - Jaroslav Špatenka
- Department of Transplantation and Tissue Banking, Czech National Allograft Heart Valve Bank, Department of Cardiovascular Surgery, Motol University Hospital, and Second Faculty of Medicine Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic
| |
Collapse
|
14
|
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.
Collapse
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.
| |
Collapse
|
15
|
Duginski GA, Ross CJ, Laurence DW, Johns CH, Lee CH. An investigation of the effect of freezing storage on the biaxial mechanical properties of excised porcine tricuspid valve anterior leaflets. J Mech Behav Biomed Mater 2019; 101:103438. [PMID: 31542570 PMCID: PMC8008703 DOI: 10.1016/j.jmbbm.2019.103438] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/27/2019] [Accepted: 09/15/2019] [Indexed: 01/03/2023]
Abstract
The atrioventricular heart valve (AHV) leaflets are critical to the facilitation of proper unidirectional blood flow through the heart. Previously, studies have been conducted to understand the tissue mechanics of healthy AHV leaflets to inform the development of valve-specific computational models and replacement materials for use in diagnosing and treating valvular heart disease. Generally, these studies involved biaxial mechanical testing of the AHV leaflet tissue specimens to extract relevant mechanical properties. Most of those studies considered freezing-based storage systems based on previous findings for other connective tissues such as aortic tissue or skin. However, there remains no study that specifically examines the effects of freezing storage on the characterized mechanical properties of the AHV leaflets. In this study, we aimed to address this gap in knowledge by performing biaxial mechanical characterizations of the tricuspid valve anterior leaflet (TVAL) tissue both before and after a 48-h freezing period. Primary findings of this study include: (i) a statistically insignificant change in the tissue extensibilities, with the frozen tissues being slightly stiffer and more anisotropic than the fresh tissues; and (ii) minimal variations in the stress relaxation behaviors between the fresh and frozen tissues, with the frozen tissues demonstrating slightly lessened relaxation. The findings from this study suggested that freezing-based storage does not significantly impact the observed mechanical properties of one of the five AHV leaflets-the TVAL. The results from this study are useful for reaffirming the experimental methodologies in the previous studies, as well as informing the tissue preservation methods of future investigations of AHV leaflet mechanics.
Collapse
Affiliation(s)
- Grace A Duginski
- Biomechanics and Biomaterials Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, 73019, USA.
| | - Colton J Ross
- Biomechanics and Biomaterials Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, 73019, USA.
| | - Devin W Laurence
- Biomechanics and Biomaterials Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, 73019, USA.
| | - Cortland H Johns
- Biomechanics and Biomaterials Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, 73019, USA.
| | - Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory (BBDL), School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK, 73019, USA; Institute for Biomedical Engineering, Science and Technology, School of Aerospace and Mechanical Engineering (IBEST), The University of Oklahoma, Norman, OK, 73019, USA.
| |
Collapse
|
16
|
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.
Collapse
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
| |
Collapse
|
17
|
Luo Y, Lou D, Ma L, Gao C. Optimizing detergent concentration and processing time to balance the decellularization efficiency and properties of bioprosthetic heart valves. J Biomed Mater Res A 2019; 107:2235-2243. [DOI: 10.1002/jbm.a.36732] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 05/13/2019] [Accepted: 05/20/2019] [Indexed: 12/28/2022]
Affiliation(s)
- Yu Luo
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and EngineeringZhejiang University Hangzhou China
| | - Dong Lou
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and EngineeringZhejiang University Hangzhou China
| | - Lie Ma
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and EngineeringZhejiang University Hangzhou China
| | - Changyou Gao
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and EngineeringZhejiang University Hangzhou China
| |
Collapse
|
18
|
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.
Collapse
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
| |
Collapse
|
19
|
Lee CH, Laurence DW, Ross CJ, Kramer KE, Babu AR, Johnson EL, Hsu MC, Aggarwal A, Mir A, Burkhart HM, Towner RA, Baumwart R, Wu Y. Mechanics of the Tricuspid Valve-From Clinical Diagnosis/Treatment, In-Vivo and In-Vitro Investigations, to Patient-Specific Biomechanical Modeling. Bioengineering (Basel) 2019; 6:E47. [PMID: 31121881 PMCID: PMC6630695 DOI: 10.3390/bioengineering6020047] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 05/16/2019] [Accepted: 05/17/2019] [Indexed: 12/29/2022] Open
Abstract
Proper tricuspid valve (TV) function is essential to unidirectional blood flow through the right side of the heart. Alterations to the tricuspid valvular components, such as the TV annulus, may lead to functional tricuspid regurgitation (FTR), where the valve is unable to prevent undesired backflow of blood from the right ventricle into the right atrium during systole. Various treatment options are currently available for FTR; however, research for the tricuspid heart valve, functional tricuspid regurgitation, and the relevant treatment methodologies are limited due to the pervasive expectation among cardiac surgeons and cardiologists that FTR will naturally regress after repair of left-sided heart valve lesions. Recent studies have focused on (i) understanding the function of the TV and the initiation or progression of FTR using both in-vivo and in-vitro methods, (ii) quantifying the biomechanical properties of the tricuspid valve apparatus as well as its surrounding heart tissue, and (iii) performing computational modeling of the TV to provide new insight into its biomechanical and physiological function. This review paper focuses on these advances and summarizes recent research relevant to the TV within the scope of FTR. Moreover, this review also provides future perspectives and extensions critical to enhancing the current understanding of the functioning and remodeling tricuspid valve in both the healthy and pathophysiological states.
Collapse
Affiliation(s)
- 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 (IBEST), 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.
| | - Colton J Ross
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
| | - Katherine E Kramer
- 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.
- Department of Biotechnology and Medical Engineering, National Institute of Technology Rourkela, Rourkela, Odisha 769008, India.
| | - Emily L Johnson
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA.
| | - Ming-Chen Hsu
- Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA.
| | - Ankush Aggarwal
- Glasgow Computational Engineering Centre, School of Engineering, University of Glasgow, Scotland G12 8LT, UK.
| | - Arshid Mir
- Division of Pediatric Cardiology, Department of Pediatrics, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Harold M Burkhart
- Division of Cardiothoracic Surgery, Department of Surgery, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
| | - Rheal A Towner
- Advance Magnetic Resonance Center, MS 60, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
| | - Ryan Baumwart
- Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
| | - Yi Wu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, The University of Oklahoma, Norman, OK 73019, USA.
| |
Collapse
|
20
|
Goth W, Potter S, Allen ACB, Zoldan J, Sacks MS, Tunnell JW. Non-Destructive Reflectance Mapping of Collagen Fiber Alignment in Heart Valve Leaflets. Ann Biomed Eng 2019; 47:1250-1264. [PMID: 30783832 PMCID: PMC6456388 DOI: 10.1007/s10439-019-02233-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 02/15/2019] [Indexed: 12/11/2022]
Abstract
Collagen fibers are the primary structural elements that define many soft-tissue structure and mechanical function relationships, so that quantification of collagen organization is essential to many disciplines. Current tissue-level collagen fiber imaging techniques remain limited in their ability to quantify fiber organization at macroscopic spatial scales and multiple time points, especially in a non-contacting manner, requiring no modifications to the tissue, and in near real-time. Our group has previously developed polarized spatial frequency domain imaging (pSFDI), a reflectance imaging technique that rapidly and non-destructively quantifies planar collagen fiber orientation in superficial layers of soft tissues over large fields-of-view. In this current work, we extend the light scattering models and image processing techniques to extract a critical measure of the degree of collagen fiber alignment, the normalized orientation index (NOI), directly from pSFDI data. Electrospun fiber samples with architectures similar to many collagenous soft tissues and known NOI were used for validation. An inverse model was then used to extract NOI from pSFDI measurements of aortic heart valve leaflets and clearly demonstrated changes in degree of fiber alignment between opposing sides of the sample. These results show that our model was capable of extracting absolute measures of degree of fiber alignment in superficial layers of heart valve leaflets with only general a priori knowledge of fiber properties, providing a novel approach to rapid, non-destructive study of microstructure in heart valve leaflets using a reflectance geometry.
Collapse
Affiliation(s)
- Will Goth
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Sam Potter
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, USA
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Alicia C B Allen
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Janet Zoldan
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Michael S Sacks
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, USA
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - James W Tunnell
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA.
- James T. Willerson Center for Cardiovascular Modeling and Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA.
| |
Collapse
|
21
|
Fiala R, Kochová P, Kubíková T, Cimrman R, Tonar Z, Špatenka J, Fabián O, Burkert J. Mechanical and structural properties of human aortic and pulmonary allografts do not deteriorate in the first 10 years of cryopreservation and storage in nitrogen. Cell Tissue Bank 2019; 20:221-241. [PMID: 30903411 DOI: 10.1007/s10561-019-09762-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 03/13/2019] [Indexed: 11/22/2022]
Abstract
The aortic and pulmonary allograft heart valves (AHV) are used in the cardiac surgery for replacing the impaired semilunar valves. They are harvested from donor hearts and cryostored in tissue banks. The expiration period was set to 5 years arbitrarily. We hypothesized that their mechanical and structural properties do not deteriorate after this period. A total of 64 human AHV (31 aortic and 33 pulmonary) of different length of cryopreservation (fresh, 0-5, 5-10, over 10 years) were sampled to different tissue strips (artery, leaflet, ventriculo-arterial junction) and tested by tensile test with loading velocity 10 mm/min until tissue rupture. Neighbouring regions of tissue were processed histologically and evaluated for elastin and collagen area fraction. The results were evaluated statistically. In aortic AHV, the physical deformation response of wall samples to stress did not changed significantly neither during the process of cryopreservation nor during the first 10 years of storage. In pulmonary AHV, the ultimate strain dropped after 5 years of cryopreservation indicating that pulmonary artery was significantly less deformable at the time of rupture. On the other hand, the ultimate stress was equal during the first 10 years of cryostorage. The changes in collagen and elastin amount in the tissue samples were not associated with mechanical impairment. Neither elasticity, stiffness and solidity nor morphology of aortic and pulmonary AHV did not change reasonably with cryopreservation and in the first 10 years of cryostorage. This evidence suggests that the expiration period might be extended in the future.
Collapse
Affiliation(s)
- Radovan Fiala
- Department of Cardiovascular Surgery, Motol University Hospital, Second Faculty of Medicine, Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic.
| | - Petra Kochová
- Department of Cardiovascular Surgery, Motol University Hospital, Second Faculty of Medicine, Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic.,NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Technická 8, Pilsen, Czech Republic
| | - Tereza Kubíková
- Department of Histology and Embryology, Biomedical Centre, Faculty of Medicine in Pilsen, Charles University, Karlovarská 48, 301 66, Pilsen, Czech Republic
| | - Robert Cimrman
- NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Technická 8, Pilsen, Czech Republic
| | - Zbyněk Tonar
- NTIS - New Technologies for the Information Society, Faculty of Applied Sciences, University of West Bohemia, Technická 8, Pilsen, Czech Republic
| | - Jaroslav Špatenka
- Department of Cardiovascular Surgery, Motol University Hospital, Second Faculty of Medicine, Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic.,Department of Transplantations and Tissue Bank, Motol University Hospital, V Úvalu 84, 150 06, Prague, Czech Republic
| | - Ondřej Fabián
- Department of Pathology and Molecular Medicine, Motol University Hospital, Second Faculty of Medicine, Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic
| | - Jan Burkert
- Department of Cardiovascular Surgery, Motol University Hospital, Second Faculty of Medicine, Charles University in Prague, V Úvalu 84, 150 06, Prague, Czech Republic.,Department of Transplantations and Tissue Bank, Motol University Hospital, V Úvalu 84, 150 06, Prague, Czech Republic
| |
Collapse
|
22
|
Surface biofunctionalization of the decellularized porcine aortic valve with VEGF-loaded nanoparticles for accelerating endothelialization. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2018; 97:632-643. [PMID: 30678950 DOI: 10.1016/j.msec.2018.12.079] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 12/09/2018] [Accepted: 12/24/2018] [Indexed: 12/15/2022]
Abstract
The original intention for building a tissue-engineered heart valve (TEHV) was to simulate a normal heart valve and overcome the insufficiency of the commonly used heart valve replacement in the clinic. The endothelialization of the TEHV is very important as the endothelialized TEHV can decrease platelet adhesion and delay the valvular calcification decline process. In this work, we encapsulated vascular endothelial growth factor (VEGF) into polycaprolactone (PCL) nanoparticles. Then, through the Michael addition reaction, PCL nanoparticles were introduced onto the decellularized aortic valve to prepare a hybrid valve. The encapsulation efficiency of the PCL nanoparticles for VEGF was up to 82%, and the in vitro accumulated release rate was slow without an evident initial burst release. In addition, the hybrid valve had a decreased hemolysis ratio and possessed antiplatelet adhesion capacity, and it was able to promote the adhesion and proliferation of endothelial cells, covering the surface with a dense cell layer to accelerate endothelialization. An experiment involving the subcutaneous implant in SD rats showed that at week 8, lots of blood capillaries were formed in the hybrid valve. Mechanics performance testing indicated that the mechanical property of the hybrid valve was partly improved. Taken together, we applied a nano-drug controlled release system to fabricate TEHV, and provide an approach for the biofunctionalization of the TEHV scaffold for accelerating endothelialization.
Collapse
|
23
|
Guo G, Jin L, Jin W, Chen L, Lei Y, Wang Y. Radical polymerization-crosslinking method for improving extracellular matrix stability in bioprosthetic heart valves with reduced potential for calcification and inflammatory response. Acta Biomater 2018; 82:44-55. [PMID: 30326277 DOI: 10.1016/j.actbio.2018.10.017] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 09/04/2018] [Accepted: 10/11/2018] [Indexed: 02/07/2023]
Abstract
In recent years, the number of heart valve replacements has multiplied with valve diseases because of aging populations and the surge in rheumatic heart disease in young people. Among them, bioprosthetic heart valves (BHVs) have become increasingly popular. Transcatheter aortic valve implantation (TAVI) valve as an emerging BHV has been increasingly applied to patients. However, the current commercially used BHVs treated with glutaraldehyde (Glut) still face the problem of durability. BHVs derived from Glut-treated xenogenetic tissues would undergo structural degeneration and calcification sometimes even as short as less than 10 years. This issue has already become a big challenge considering more and more young patients at the age of 50-60 s are receiving the BHV replacement. In our study, an approach that is totally different from the previous techniques named by us as the radical polymerization-crosslinking (RPC) method was developed to improve extracellular matrix stability, prevent calcification, and reduce inflammatory response in BHVs. The porcine pericardium (PP) tissue was decellularized, functionalized with methacryloyl groups, and subsequently crosslinked by radical polymerization. We found that high-density RPC treatment remarkably improved the stability of collagen and elastin of PP, enhanced its endothelialization potential, and provided reliable biomechanical performance as compared to Glut treatment. The in vivo rat model also confirmed the increased componential stability and the reduced inflammatory response of RPC-treated PP. Moreover, the RPC-treated PP showed better in vivo anticalcification potential than Glut-treated PP. STATEMENT OF SIGNIFICANCE: Bioprosthetic heart valves (BHVs) manufactured from glutaraldehyde (Glut)-treated xenogeneic tissues have been used to treat valve-related diseases for several decades. However, the durability of BHVs remains unresolved and becomes more pronounced particularly in younger patients. Although a number of new alternative methods for Glut crosslinking have been proposed, their overall performance is still far from ready to use in humans. In this study, radical polymerization was investigated for crosslinking the porcine pericardium (PP). This treatment was found to have advantages compared to Glut-treated PP in terms of stability, biocompatibility, and anticalcification potential with the hope of addressing the needs of more robust biomaterials for the fabrication of BHVs.
Collapse
|
24
|
Straka F, Schornik D, Masin J, Filova E, Mirejovsky T, Burdikova Z, Svindrych Z, Chlup H, Horny L, Daniel M, Machac J, Skibová J, Pirk J, Bacakova L. A human pericardium biopolymeric scaffold for autologous heart valve tissue engineering: cellular and extracellular matrix structure and biomechanical properties in comparison with a normal aortic heart valve. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2018; 29:599-634. [PMID: 29338582 DOI: 10.1080/09205063.2018.1429732] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The objective of our study was to compare the cellular and extracellular matrix (ECM) structure and the biomechanical properties of human pericardium (HP) with the normal human aortic heart valve (NAV). HP tissues (from 12 patients) and NAV samples (from 5 patients) were harvested during heart surgery. The main cells in HP were pericardial interstitial cells, which are fibroblast-like cells of mesenchymal origin similar to the valvular interstitial cells in NAV tissue. The ECM of HP had a statistically significantly (p < 0.001) higher collagen I content, a lower collagen III and elastin content, and a similar glycosaminoglycans (GAGs) content, in comparison with the NAV, as measured by ECM integrated density. However, the relative thickness of the main load-bearing structures of the two tissues, the dense part of fibrous HP (49 ± 2%) and the lamina fibrosa of NAV (47 ± 4%), was similar. In both tissues, the secant elastic modulus (Es) was significantly lower in the transversal direction (p < 0.05) than in the longitudinal direction. This proved that both tissues were anisotropic. No statistically significant differences in UTS (ultimate tensile strength) values and in calculated bending stiffness values in the longitudinal or transversal direction were found between HP and NAV. Our study confirms that HP has an advantageous ECM biopolymeric structure and has the biomechanical properties required for a tissue from which an autologous heart valve replacement may be constructed.
Collapse
Affiliation(s)
- Frantisek Straka
- a Cardiology Centre and Cardiovascular Surgery Department , Institute for Clinical and Experimental Medicine , Prague , Czech Republic.,b Department of Biomaterials and Tissue Engineering , Institute of Physiology, Academy of Sciences of the Czech Republic , Prague , Czech Republic
| | - David Schornik
- b Department of Biomaterials and Tissue Engineering , Institute of Physiology, Academy of Sciences of the Czech Republic , Prague , Czech Republic
| | - Jaroslav Masin
- a Cardiology Centre and Cardiovascular Surgery Department , Institute for Clinical and Experimental Medicine , Prague , Czech Republic
| | - Elena Filova
- b Department of Biomaterials and Tissue Engineering , Institute of Physiology, Academy of Sciences of the Czech Republic , Prague , Czech Republic
| | - Tomas Mirejovsky
- c Clinical and Transplant Pathology Department, Institute for Clinical and Experimental Medicine , Prague , Czech Republic
| | - Zuzana Burdikova
- d Department of Cell Biology, School of Medicine , University of Virginia , Charlottesville , VA , USA
| | - Zdenek Svindrych
- e Department of Biology, W. M, Keck Center for Cellular Imaging , University of Virginia , Charlottesville , VA , USA
| | - Hynek Chlup
- f Faculty of Mechanical Engineering, Department of Mechanics, Biomechanics and Mechatronics , Czech Technical University in Prague , Prague , Czech Republic
| | - Lukas Horny
- f Faculty of Mechanical Engineering, Department of Mechanics, Biomechanics and Mechatronics , Czech Technical University in Prague , Prague , Czech Republic
| | - Matej Daniel
- f Faculty of Mechanical Engineering, Department of Mechanics, Biomechanics and Mechatronics , Czech Technical University in Prague , Prague , Czech Republic
| | - Jiri Machac
- g Institute of Botany CAS, Academy of Sciences of the Czech Republic , Pruhonice , Czech Republic
| | - Jelena Skibová
- h Department of Medical Statistics , Institute for Clinical and Experimental Medicine , Prague , Czech Republic
| | - Jan Pirk
- a Cardiology Centre and Cardiovascular Surgery Department , Institute for Clinical and Experimental Medicine , Prague , Czech Republic
| | - Lucie Bacakova
- b Department of Biomaterials and Tissue Engineering , Institute of Physiology, Academy of Sciences of the Czech Republic , Prague , Czech Republic
| |
Collapse
|
25
|
Abstract
The purpose of this study was to determine the impact of elevated temperature exposure in tissue banking on soft tissues. A secondary objective was to determine the relative ability of various assays to detect changes in soft tissues due to temperature deviations. Porcine pulmonary heart valve leaflets exposed to 37 °C were compared with those incubated at 52 and 67 °C for 10, 30 and 100 min. The analytical methods consisted of (1) viability assessment using the resazurin assay, (2) collagen content using the Sircol assay, and (3) permeability assessment using an electrical conductivity assay. Additionally, histology and two photon microscopy were used to reveal mechanisms of cell and tissue damage. Viability, collagen content, and permeability all decreased following heat treatment. In terms of statistical significance with respect to treatment temperature, cell viability was most affected (p < 0.0001), followed by permeability (p < 0.0001), and then collagen content (p = 0.13). After heat treatment, histology indicated increased apoptosis and two photon microscopy revealed a decrease in collagen fiber organization and an increase in elastin density. These results suggest that measures of cell viability would be best for assessing tissues where the cells are alive and that permeability may be best where cell viability is not intentionally maintained.
Collapse
|
26
|
Vafaee T, Thomas D, Desai A, Jennings LM, Berry H, Rooney P, Kearney J, Fisher J, Ingham E. Decellularization of human donor aortic and pulmonary valved conduits using low concentration sodium dodecyl sulfate. J Tissue Eng Regen Med 2017; 12:e841-e853. [PMID: 27943656 PMCID: PMC5836965 DOI: 10.1002/term.2391] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 10/11/2016] [Accepted: 12/06/2016] [Indexed: 11/11/2022]
Abstract
The clinical use of decellularized cardiac valve allografts is increasing. Long‐term data will be required to determine whether they outperform conventional cryopreserved allografts. Valves decellularized using different processes may show varied long‐term outcomes. It is therefore important to understand the effects of specific decellularization technologies on the characteristics of donor heart valves. Human cryopreserved aortic and pulmonary valved conduits were decellularized using hypotonic buffer, 0.1% (w/v) sodium dodecyl sulfate and nuclease digestion. The decellularized tissues were compared to cellular cryopreserved valve tissues using histology, immunohistochemistry, quantitation of total deoxyribose nucleic acid, collagen and glycosaminoglycan content, in vitro cytotoxicity assays, uniaxial tensile testing and subcutaneous implantation in mice. The decellularized tissues showed no histological evidence of cells or cell remnants and >97% deoxyribose nucleic acid removal in all regions (arterial wall, muscle, leaflet and junction). The decellularized tissues retained collagen IV and von Willebrand factor staining with some loss of fibronectin, laminin and chondroitin sulfate staining. There was an absence of major histocompatibility complex Class I staining in decellularized pulmonary valve tissues, with only residual staining in isolated areas of decellularized aortic valve tissues. The collagen content of the tissues was not decreased following decellularization however the glycosaminoglycan content was reduced. Only moderate changes in the maximum load to failure of the tissues were recorded postdecellularization. The decellularized tissues were noncytotoxic in vitro, and were biocompatible in vivo in a mouse subcutaneous implant model. The decellularization process will now be translated into a good manufacturing practices‐compatible process for donor cryopreserved valves with a view to future clinical use. Copyright © 2016 The Authors Tissue Engineering and Regenerative Medicine published by John Wiley & Sons, Ltd.
Collapse
Affiliation(s)
- Tayyebeh Vafaee
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Daniel Thomas
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Amisha Desai
- Institute of Medical & Biological Engineering, School of Mechanical Engineering, University of Leeds, UK
| | - Louise M Jennings
- Institute of Medical & Biological Engineering, School of Mechanical Engineering, University of Leeds, UK
| | - Helen Berry
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK.,The Biocentre, The Biocentre, Innovation Way, Heslington, York, UK
| | - Paul Rooney
- Tissue & Eye Services, NHS Blood & Transplant, Estuary Bank, Speke, Liverpool, UK
| | - John Kearney
- Tissue & Eye Services, NHS Blood & Transplant, Estuary Bank, Speke, Liverpool, UK
| | - John Fisher
- Institute of Medical & Biological Engineering, School of Mechanical Engineering, University of Leeds, UK
| | - Eileen Ingham
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| |
Collapse
|
27
|
VeDepo MC, Buse EE, Quinn RW, Williams TD, Detamore MS, Hopkins RA, Converse GL. Species-specific effects of aortic valve decellularization. Acta Biomater 2017; 50:249-258. [PMID: 28069510 DOI: 10.1016/j.actbio.2017.01.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 12/05/2016] [Accepted: 01/05/2017] [Indexed: 01/12/2023]
Abstract
Decellularized heart valves have great potential as a stand-alone valve replacement or as a scaffold for tissue engineering heart valves. Before decellularized valves can be widely used clinically, regulatory standards require pre-clinical testing in an animal model, often sheep. Numerous decellularization protocols have been applied to both human and ovine valves; however, the ways in which a specific process may affect valves of these species differently have not been reported. In the current study, the comparative effects of decellularization were evaluated for human and ovine aortic valves by measuring mechanical and biochemical properties. Cell removal was equally effective for both species. The initial cell density of the ovine valve leaflets (2036±673cells/mm2) was almost triple the cell density of human leaflets (760±386cells/mm2; p<0.001). Interestingly, post-decellularization ovine leaflets exhibited significant increases in biaxial areal strain (p<0.001) and circumferential peak stretch (p<0.001); however, this effect was not observed in the human counterparts (p>0.10). This species-dependent difference in the effect of decellularization was likely due to the higher initial cellularity in ovine valves, as well as a significant decrease in collagen crosslinking following the decellularization of ovine leaflets that was not observed in the human leaflet. Decellularization also caused a significant decrease in the circumferential relaxation of ovine leaflets (p<0.05), but not human leaflets (p>0.30), which was credited to a greater reduction of glycosaminoglycans in the ovine tissue post-decellularization. These results indicate that an identical decellularization process can have differing species-specific effects on heart valves. STATEMENT OF SIGNIFICANCE The decellularized heart valve offers potential as an improved heart valve substitute and as a scaffold for the tissue engineered heart valve; however, the consequences of processing must be fully characterized. To date, the effects of decellularization on donor valves from different species have not been evaluated in such a way that permits direct comparison between species. In this manuscript, we report species-dependent variation in the biochemical and biomechanical properties of human and ovine aortic heart valve leaflets following decellularization. This is of clinical significance, as current regulatory guidelines required pre-clinical use of the ovine model to evaluate candidate heart valve substitutes.
Collapse
Affiliation(s)
- Mitchell C VeDepo
- Cardiac Regenerative Surgery Research Laboratories of The Ward Family Heart Center, Children's Mercy Kansas City, 2401 Gillham Road, Kansas City, MO 64108, United States; Bioengineering Program, University of Kansas, 3135A Learned Hall, 1530 W. 15th St., Lawrence, KS 66045, United States
| | - Eric E Buse
- Cardiac Regenerative Surgery Research Laboratories of The Ward Family Heart Center, Children's Mercy Kansas City, 2401 Gillham Road, Kansas City, MO 64108, United States
| | - Rachael W Quinn
- Cardiac Regenerative Surgery Research Laboratories of The Ward Family Heart Center, Children's Mercy Kansas City, 2401 Gillham Road, Kansas City, MO 64108, United States
| | - Todd D Williams
- University of Kansas Mass Spectrometry Laboratory, 3006 Malott Hall, 1251 Wescoe Hall Drive, Lawrence, KS 66045, United States
| | - Michael S Detamore
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK 73019, United States
| | - Richard A Hopkins
- Cardiac Regenerative Surgery Research Laboratories of The Ward Family Heart Center, Children's Mercy Kansas City, 2401 Gillham Road, Kansas City, MO 64108, United States
| | - Gabriel L Converse
- Cardiac Regenerative Surgery Research Laboratories of The Ward Family Heart Center, Children's Mercy Kansas City, 2401 Gillham Road, Kansas City, MO 64108, United States.
| |
Collapse
|
28
|
Tam H, Zhang W, Infante D, Parchment N, Sacks M, Vyavahare N. Fixation of Bovine Pericardium-Based Tissue Biomaterial with Irreversible Chemistry Improves Biochemical and Biomechanical Properties. J Cardiovasc Transl Res 2017; 10:194-205. [PMID: 28213846 DOI: 10.1007/s12265-017-9733-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 01/26/2017] [Indexed: 10/20/2022]
Abstract
Bioprosthetic heart valves (BHVs), derived from glutaraldehyde crosslinked (GLUT) porcine aortic valve leaflets or bovine pericardium (BP), are used to replace defective heart valves. However, valve failure can occur within 12-15 years due to calcification and/or progressive structural degeneration. We present a novel fabrication method that utilizes carbodiimide, neomycin trisulfate, and pentagalloyl glucose crosslinking chemistry (TRI) to better stabilize the extracellular matrix of BP. We demonstrate that TRI-treated BP is more compliant than GLUT-treated BP. GLUT-treated BP exhibited permanent geometric deformation and complete alteration of apparent mechanical properties when subjected to induced static strain. TRI BP, on the other hand, did not exhibit such permanent geometric deformations or significant alterations of apparent mechanical properties. TRI BP also exhibited better resistance to enzymatic degradation in vitro and calcification in vivo when implanted subcutaneously in juvenile rats for up to 30 days.
Collapse
Affiliation(s)
- H Tam
- Department of Bioengineering, Clemson University, Clemson, SC, 29634, USA
| | - W Zhang
- Department of Biomedical Engineering, University of Texas, Austin, TX, USA
| | - D Infante
- Department of Bioengineering, Clemson University, Clemson, SC, 29634, USA
| | - N Parchment
- Department of Bioengineering, Clemson University, Clemson, SC, 29634, USA
| | - M Sacks
- Department of Biomedical Engineering, University of Texas, Austin, TX, USA
| | - N Vyavahare
- Department of Bioengineering, Clemson University, Clemson, SC, 29634, USA.
| |
Collapse
|
29
|
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.
Collapse
|
30
|
Mattson JM, Turcotte R, Zhang Y. Glycosaminoglycans contribute to extracellular matrix fiber recruitment and arterial wall mechanics. Biomech Model Mechanobiol 2017; 16:213-225. [PMID: 27491312 PMCID: PMC5288264 DOI: 10.1007/s10237-016-0811-4] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 07/26/2016] [Indexed: 01/15/2023]
Abstract
Elastic and collagen fibers are well known to be the major load-bearing extracellular matrix (ECM) components of the arterial wall. Studies of the structural components and mechanics of arterial ECM generally focus on elastin and collagen fibers, and glycosaminoglycans (GAGs) are often neglected. Although GAGs represent only a small component of the vessel wall ECM, they are considerably important because of their diverse functionality and their role in pathological processes. The goal of this study was to study the mechanical and structural contributions of GAGs to the arterial wall. Biaxial tensile testing was paired with multiphoton microscopic imaging of elastic and collagen fibers in order to establish the structure-function relationships of porcine thoracic aorta before and after enzymatic GAG removal. Removal of GAGs results in an earlier transition point of the nonlinear stress-strain curves [Formula: see text]. However, stiffness was not significantly different after GAG removal treatment, indicating earlier but not absolute stiffening. Multiphoton microscopy showed that when GAGs are removed, the adventitial collagen fibers are straighter, and both elastin and collagen fibers are recruited at lower levels of strain, in agreement with the mechanical change. The amount of stress relaxation also decreased in GAG-depleted arteries [Formula: see text]. These findings suggest that the interaction between GAGs and other ECM constituents plays an important role in the mechanics of the arterial wall, and GAGs should be considered in addition to elastic and collagen fibers when studying arterial function.
Collapse
Affiliation(s)
- Jeffrey M Mattson
- Department of Mechanical Engineering, Boston University, Boston, MA, USA
| | - Raphaël Turcotte
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
- Advanced Microscopy Program, Center for Systems Biology, Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Yanhang Zhang
- Department of Mechanical Engineering, Boston University, Boston, MA, USA.
- Department of Biomedical Engineering, Boston University, Boston, MA, USA.
| |
Collapse
|
31
|
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.
Collapse
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.
| |
Collapse
|
32
|
Abstract
Fibrous structures are an integral and dynamic feature of soft biological tissues that are directly related to the tissues' condition and function. A greater understanding of mechanical tissue behavior can be gained through quantitative analyses of structure alone, as well as its integration into computational models of soft tissue function. Histology and other nonoptical techniques have traditionally dominated the field of tissue imaging, but they are limited by their invasiveness, inability to provide resolution on the micrometer scale, and dynamic information. Recent advances in optical modalities can provide higher resolution, less invasive imaging capabilities, and more quantitative measurements. Here we describe contemporary optical imaging techniques with respect to their suitability in the imaging of tissue structure, with a focus on characterization and implementation into subsequent modeling efforts. We outline the applications and limitations of each modality and discuss the overall shortcomings and future directions for optical imaging of soft tissue structure.
Collapse
Affiliation(s)
- Will Goth
- Department of Biomedical Engineering
| | - John Lesicko
- Department of Biomedical Engineering
- Center for Cardiovascular Simulation, and
| | - Michael S Sacks
- Department of Biomedical Engineering
- Center for Cardiovascular Simulation, and
- Institute for Computational Engineering and Sciences, University of Texas, Austin, Texas 78712;
| | | |
Collapse
|
33
|
Murienne BJ, Chen ML, Quigley HA, Nguyen TD. The contribution of glycosaminoglycans to the mechanical behaviour of the posterior human sclera. J R Soc Interface 2016; 13:20160367. [PMID: 27358279 PMCID: PMC4938097 DOI: 10.1098/rsif.2016.0367] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 06/06/2016] [Indexed: 01/26/2023] Open
Abstract
We characterized the structural and mechanical changes after experimental digestion of sulfated glycosaminoglycans (s-GAGs) in the human posterior sclera, using ultrasound thickness measurements and an inflation test with three-dimensional digital image correlation (3D-DIC). Each scleral specimen was first incubated in a buffer solution to return to full hydration, inflation tested, treated in a buffer solution with chondroitinase ABC (ChABC), then inflation tested again. After each test series, the thickness of eight locations was measured. After enzymatic treatment, the average scleral thickness decreased by 13.3% (p < 0.001) and there was a stiffer overall stress-strain response (p < 0.05). The stress-strain response showed a statistically significant increase in the low-pressure stiffness, high-pressure stiffness and hysteresis. Thus, s-GAGs play a measurable role in the mechanical behaviour of the posterior human sclera.
Collapse
Affiliation(s)
- Barbara J Murienne
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Michelle L Chen
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Harry A Quigley
- Glaucoma Center of Excellence, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Thao D Nguyen
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA
| |
Collapse
|
34
|
Puperi DS, O’Connell RW, Punske ZE, Wu Y, West JL, Grande-Allen KJ. Hyaluronan Hydrogels for a Biomimetic Spongiosa Layer of Tissue Engineered Heart Valve Scaffolds. Biomacromolecules 2016; 17:1766-75. [PMID: 27120017 PMCID: PMC4986518 DOI: 10.1021/acs.biomac.6b00180] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Advanced tissue engineered heart valves must be constructed from multiple materials to better mimic the heterogeneity found in the native valve. The trilayered structure of aortic valves provides the ability to open and close consistently over a full human lifetime, with each layer performing specific mechanical functions. The middle spongiosa layer consists primarily of proteoglycans and glycosaminoglycans, providing lubrication and dampening functions as the valve leaflet flexes open and closed. In this study, hyaluronan hydrogels were tuned to perform the mechanical functions of the spongiosa layer, provide a biomimetic scaffold in which valve cells were encapsulated in 3D for tissue engineering applications, and gain insight into how valve cells maintain hyaluronan homeostasis within heart valves. Expression of the HAS1 isoform of hyaluronan synthase was significantly higher in hyaluronan hydrogels compared to blank-slate poly(ethylene glycol) diacrylate (PEGDA) hydrogels. Hyaluronidase and matrix metalloproteinase enzyme activity was similar between hyaluronan and PEGDA hydrogels, even though these scaffold materials were each specifically susceptible to degradation by different enzyme types. KIAA1199 was expressed by valve cells and may play a role in the regulation of hyaluronan in heart valves. Cross-linked hyaluronan hydrogels maintained healthy phenotype of valve cells in 3D culture and were tuned to approximate the mechanical properties of the valve spongiosa layer. Therefore, hyaluronan can be used as an appropriate material for the spongiosa layer of a proposed laminate tissue engineered heart valve scaffold.
Collapse
Affiliation(s)
- Daniel S. Puperi
- Department of Bioengineering, Rice University, Houston, Texas 77005, United States
| | - Ronan W. O’Connell
- Department of Biomedical Engineering, University of Glasgow, Glasgow, United Kingdom
| | - Zoe E. Punske
- Department of Bioengineering, Rice University, Houston, Texas 77005, United States
| | - Yan Wu
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Jennifer L. West
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
| | - K. Jane Grande-Allen
- Department of Bioengineering, Rice University, Houston, Texas 77005, United States
| |
Collapse
|
35
|
Zhang W, Ayoub S, Liao J, Sacks MS. A meso-scale layer-specific structural constitutive model of the mitral heart valve leaflets. Acta Biomater 2016; 32:238-255. [PMID: 26712602 DOI: 10.1016/j.actbio.2015.12.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Revised: 11/13/2015] [Accepted: 12/01/2015] [Indexed: 11/28/2022]
Abstract
Fundamental to developing a deeper understanding of pathophysiological remodeling in mitral valve (MV) disease is the development of an accurate tissue-level constitutive model. In the present work, we developed a novel meso-scale (i.e. at the level of the fiber, 10-100 μm in length scale) structural constitutive model (MSSCM) for MV leaflet tissues. Due to its four-layer structure, we focused on the contributions from the distinct collagen and elastin fiber networks within each tissue layer. Requisite collagen and elastin fibrous structural information for each layer were quantified using second harmonic generation microscopy and conventional histology. A comprehensive mechanical dataset was also used to guide model formulation and parameter estimation. Furthermore, novel to tissue-level structural constitutive modeling approaches, we allowed the collagen fiber recruitment function to vary with orientation. Results indicated that the MSSCM predicted a surprisingly consistent mean effective collagen fiber modulus of 162.72 MPa, and demonstrated excellent predictive capability for extra-physiological loading regimes. There were also anterior-posterior leaflet-specific differences, such as tighter collagen and elastin fiber orientation distributions (ODF) in the anterior leaflet, and a thicker and stiffer atrialis in the posterior leaflet. While a degree of angular variance was observed, the tight valvular tissue ODF also left little room for any physically meaningful angular variance in fiber mechanical responses. Finally, a novel fibril-level (0.1-1 μm) validation approach was used to compare the predicted collagen fiber/fibril mechanical behavior with extant MV small angle X-ray scattering data. Results demonstrated excellent agreement, indicating that the MSSCM fully captures the tissue-level function. Future utilization of the MSSCM in computational models of the MV will aid in producing highly accurate simulations in non-physiological loading states that can occur in repair situations, as well as guide the form of simplified models for real-time simulation tools.
Collapse
Affiliation(s)
- Will Zhang
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Salma Ayoub
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Jun Liao
- Tissue Bioengineering Laboratory, Department of Ag. and Bio. Engineering, Bagley College of Engineering, College of Agriculture and Life Sciences, Mississippi State University, MS, USA
| | - Michael S Sacks
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA.
| |
Collapse
|
36
|
Sacks MS, Zhang W, Wognum S. A novel fibre-ensemble level constitutive model for exogenous cross-linked collagenous tissues. Interface Focus 2016; 6:20150090. [PMID: 26855761 DOI: 10.1098/rsfs.2015.0090] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Exogenous cross-linking of soft collagenous tissues is a common method for biomaterial development and medical therapies. To enable improved applications through computational methods, physically realistic constitutive models are required. Yet, despite decades of research, development and clinical use, no such model exists. In this study, we develop the first rigorous full structural model (i.e. explicitly incorporating various features of the collagen fibre architecture) for exogenously cross-linked soft tissues. This was made possible, in-part, with the use of native to cross-linked matched experimental datasets and an extension to the collagenous structural constitutive model so that the uncross-linked collagen fibre responses could be mapped to the cross-linked configuration. This allowed us to separate the effects of cross-linking from kinematic changes induced in the cross-linking process, which in turn allowed the non-fibrous tissue matrix component and the interaction effects to be identified. It was determined that the matrix could be modelled as an isotropic material using a modified Yeoh model. The most novel findings of this study were that: (i) the effective collagen fibre modulus was unaffected by cross-linking and (ii) fibre-ensemble interactions played a large role in stress development, often dominating the total tissue response (depending on the stress component and loading path considered). An important utility of the present model is its ability to separate the effects of exogenous cross-linking on the fibres from changes due to the matrix. Applications of this approach include the utilization in the design of novel chemical treatments to produce specific mechanical responses and the study of fatigue damage in bioprosthetic heart valve biomaterials.
Collapse
Affiliation(s)
- 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, PO Box 5.236, Stop C0200, Austin, TX 78712 , 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, PO Box 5.236, Stop C0200, Austin, TX 78712 , USA
| | - Silvia Wognum
- Department of Biomedical Engineering , Eindhoven University of Technology , PO Box 513, 5600 MB Eindhoven , The Netherlands
| |
Collapse
|
37
|
Cells and extracellular matrix interplay in cardiac valve disease: because age matters. Basic Res Cardiol 2016; 111:16. [PMID: 26830603 DOI: 10.1007/s00395-016-0534-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 12/27/2015] [Accepted: 01/19/2016] [Indexed: 12/18/2022]
Abstract
Cardiovascular aging is a physiological process affecting all components of the heart. Despite the interest and experimental effort lavished on aging of cardiac cells, increasing evidence is pointing at the pivotal role of extracellular matrix (ECM) in cardiac aging. Structural and molecular changes in ECM composition during aging are at the root of significant functional modifications at the level of cardiac valve apparatus. Indeed, calcification or myxomatous degeneration of cardiac valves and their functional impairment can all be explained in light of age-related ECM alterations and the reciprocal interplay between altered ECM and cellular elements populating the leaflet, namely valvular interstitial cells and valvular endothelial cells, is additionally affecting valve function with striking reflexes on the clinical scenario. The initial experimental findings on this argument are underlining the need for a more comprehensive understanding on the biological mechanisms underlying ECM aging and remodeling as potentially constituting a pharmacological therapeutic target or a basis to improve existing prosthetic devices and treatment options. Given the lack of systematic knowledge on this topic, this review will focus on the ECM changes that occur during aging and on their clinical translational relevance and implications in the bedside scenario.
Collapse
|
38
|
Zhu Z, Zhou J, Ding J, Xu J, Zhong H, Lei S. A novel approach to prepare a tissue engineering decellularized valve scaffold with poly(ethylene glycol)–poly(ε-caprolactone). RSC Adv 2016. [DOI: 10.1039/c5ra22808e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The objective of this study was to explore the feasibility of preparing a decellularized valve scaffold with methoxy poly(ethylene glycol)–poly(ε-caprolactone) (MPEG–PCL).
Collapse
Affiliation(s)
- Zhigang Zhu
- Department of Cardiothoracic Surgery
- The Second Affiliated Hospital of Nanchang University
- Nanchang
- P. R. China
| | - Jianliang Zhou
- Department of Cardiothoracic Surgery
- The Second Affiliated Hospital of Nanchang University
- Nanchang
- P. R. China
| | - Jingli Ding
- Department of Gastroenterology
- The Second Affiliated Hospital of Nanchang University
- Nanchang
- P. R. China
| | - Jianjun Xu
- Department of Cardiothoracic Surgery
- The Second Affiliated Hospital of Nanchang University
- Nanchang
- P. R. China
| | - Haijun Zhong
- School of Pharmacy
- Nanchang University
- Nanchang
- P. R. China
| | - Shuijin Lei
- School of Materials Science and Engineering
- Nanchang University
- Nanchang
- P. R. China
| |
Collapse
|
39
|
Brougham CM, Levingstone TJ, Jockenhoevel S, Flanagan TC, O'Brien FJ. Incorporation of fibrin into a collagen-glycosaminoglycan matrix results in a scaffold with improved mechanical properties and enhanced capacity to resist cell-mediated contraction. Acta Biomater 2015; 26:205-14. [PMID: 26297884 DOI: 10.1016/j.actbio.2015.08.022] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 08/11/2015] [Accepted: 08/18/2015] [Indexed: 12/21/2022]
Abstract
Fibrin has many uses as a tissue engineering scaffold, however many in vivo studies have shown a reduction in function resulting from the susceptibility of fibrin to cell-mediated contraction. The overall aim of the present study was to develop and characterise a reinforced natural scaffold using fibrin, collagen and glycosaminoglycan (FCG), and to examine the cell-mediated contraction of this scaffold in comparison to fibrin gels. Through the use of an injection loading technique, a homogenous FCG scaffold was developed. Mechanical testing showed a sixfold increase in compressive modulus and a thirtyfold increase in tensile modulus of fibrin when reinforced with a collagen-glycosaminoglycan backbone structure. Human vascular smooth muscle cells (vSMCs) were successfully incorporated into the FCG scaffold and demonstrated excellent viability over 7 days, while proliferation of these cells also increased significantly. VSMCs were seeded into both FCG and fibrin-only gels at the same seeding density for 7 days and while FCG scaffolds did not demonstrate a reduction in size, fibrin-only gels contracted to 10% of their original diameter. The FCG scaffold, which is composed of natural biomaterials, shows potential for use in applications where dimensional stability is crucial to the functionality of the tissue. STATEMENT OF SIGNIFICANCE Fibrin is a versatile scaffold for tissue engineering applications, but its weak mechanical properties leave it susceptible to cell-mediated contraction, meaning the dimensions of the fibrin construct will change over time. We have reinforced fibrin with a collagen glycosaminoglycan matrix and characterised the mechanical properties and bioactivity of the reinforced fibrin (FCG). This is the first scaffold manufactured from all naturally derived materials that resists cell-mediated contraction. In fact, over 7 days, the FCG scaffold fully resisted cell-mediated contraction of vascular smooth muscle cells. This FCG scaffold has many potential applications where natural scaffold materials can encourage regeneration.
Collapse
Affiliation(s)
- Claire M Brougham
- Tissue Engineering Research Group, Dept. of Anatomy, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland; School of Mechanical and Design Engineering, Dublin Institute of Technology, Bolton St, Dublin 1, Ireland; Advanced Materials and Bioengineering Research (AMBER) Centre, RCSI & TCD, Ireland
| | - Tanya J Levingstone
- Tissue Engineering Research Group, Dept. of Anatomy, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland; Advanced Materials and Bioengineering Research (AMBER) Centre, RCSI & TCD, Ireland; Trinity Centre for Bioengineering, Trinity College Dublin, Dublin 2, Ireland
| | - Stefan Jockenhoevel
- AME-Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstr. 20, 52074 Aachen, Germany
| | - Thomas C Flanagan
- School of Medicine & Medical Science, University College Dublin, Dublin 4, Ireland
| | - Fergal J O'Brien
- Tissue Engineering Research Group, Dept. of Anatomy, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland; Advanced Materials and Bioengineering Research (AMBER) Centre, RCSI & TCD, Ireland; Trinity Centre for Bioengineering, Trinity College Dublin, Dublin 2, Ireland.
| |
Collapse
|
40
|
Tam H, Zhang W, Feaver KR, Parchment N, Sacks MS, Vyavahare N. A novel crosslinking method for improved tear resistance and biocompatibility of tissue based biomaterials. Biomaterials 2015. [PMID: 26196535 DOI: 10.1016/j.biomaterials.2015.07.011] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Over 300,000 heart valve replacements are performed annually to replace stenotic and regurgitant heart valves. Bioprosthetic heart valves (BHVs), derived from glutaraldehyde crosslinked (GLUT) porcine aortic valve leaflets or bovine pericardium are often used. However, valve failure can occur within 12-15 years due to calcification and/or progressive degeneration. In this study, we have developed a novel fabrication method that utilizes carbodiimide, neomycin trisulfate, and pentagalloyl glucose crosslinking chemistry (TRI) to better stabilize the extracellular matrix of porcine aortic valve leaflets. We demonstrate that TRI treated leaflets show similar biomechanics to GLUT crosslinked leaflets. TRI treated leaflets had better resistance to enzymatic degradation in vitro and demonstrated better tearing toughness after challenged with enzymatic degradation. When implanted subcutaneously in rats for up to 90 days, GLUT control leaflets calcified heavily while TRI treated leaflets resisted calcification, retained more ECM components, and showed better biocompatibility.
Collapse
Affiliation(s)
- Hobey Tam
- Cardiovascular Implant Research Laboratory, Department of Bioengineering, Clemson University, Clemson, SC, 29634, USA
| | - Will Zhang
- Center for Computational Simulation, Institute for Computational Sciences and Engineering, Department of Biomedical Engineering, University of Texas, Austin, Austin, TX, 78712, USA
| | - Kristen R Feaver
- Center for Computational Simulation, Institute for Computational Sciences and Engineering, Department of Biomedical Engineering, University of Texas, Austin, Austin, TX, 78712, USA
| | - Nathaniel Parchment
- Cardiovascular Implant Research Laboratory, Department of Bioengineering, Clemson University, Clemson, SC, 29634, USA
| | - Michael S Sacks
- Center for Computational Simulation, Institute for Computational Sciences and Engineering, Department of Biomedical Engineering, University of Texas, Austin, Austin, TX, 78712, USA
| | - Naren Vyavahare
- Cardiovascular Implant Research Laboratory, Department of Bioengineering, Clemson University, Clemson, SC, 29634, USA.
| |
Collapse
|
41
|
Bracaglia LG, Yu L, Hibino N, Fisher JP. Reinforced pericardium as a hybrid material for cardiovascular applications. Tissue Eng Part A 2015; 20:2807-16. [PMID: 25236439 DOI: 10.1089/ten.tea.2014.0516] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Pericardium-based cardiovascular devices are currently bound by a 10-year maximum lifetime due to detrimental calcification and degradation. The goal of this work is to develop a novel synthetic material to create a lasting replacement for malfunctioning or diseased tissue in the cardiovascular system. This study couples poly(propylene fumarate) (PPF) and a natural biomaterial together in an unprecedented hybrid composite and evaluates the composite versus the standard glutaraldehyde-treated tissue. The polymer reinforcement is hypothesized to provide initial physical protection from proteolytic enzymes and degradation, but leave the original collagen and elastin matrix unaltered. The calcification rate and durability of the hybrid material are evaluated in vitro and in an in vivo subdermal animal model. Results demonstrate that PPF is an effective support and leads to significantly less calcium deposition, important metrics when evaluating cardiovascular material. By avoiding chemical crosslinking of the tissue and associated side effects, PPF-reinforced pericardium as a biohybrid material offers a promising potential direction for further development in cardiovascular material alternatives. Eliminating the basis for the majority of cardiovascular prosthetic failures could revolutionize expectations for extent of cardiovascular repair.
Collapse
Affiliation(s)
- Laura G Bracaglia
- 1 Fischell Department of Bioengineering, University of Maryland , College Park, Maryland
| | | | | | | |
Collapse
|
42
|
A review of: Application of synthetic scaffold in tissue engineering heart valves. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2015; 48:556-65. [DOI: 10.1016/j.msec.2014.12.016] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 08/26/2014] [Accepted: 12/05/2014] [Indexed: 01/28/2023]
|
43
|
Murienne BJ, Jefferys JL, Quigley HA, Nguyen TD. The effects of glycosaminoglycan degradation on the mechanical behavior of the posterior porcine sclera. Acta Biomater 2015; 12:195-206. [PMID: 25448352 DOI: 10.1016/j.actbio.2014.10.033] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 08/28/2014] [Accepted: 10/23/2014] [Indexed: 10/24/2022]
Abstract
Pathological changes in scleral glycosaminoglycan (GAG) content and in scleral mechanical properties have been observed in eyes with glaucoma and myopia. The purpose of this study is to investigate the effect of GAG removal on the scleral mechanical properties to better understand the impact of GAG content variations in the pathophysiology of glaucoma and myopia. We measured how the removal of sulphated GAG (s-GAG) affected the hydration, thickness and mechanical properties of the posterior sclera in enucleated eyes of 6-9 month-old pigs. Measurements were made in 4 regions centered on the optic nerve head (ONH) and evaluated under 3 conditions: no treatment (control), after treatment in buffer solution alone, and after treatment in buffer containing chondroitinase ABC (ChABC) to remove s-GAGs. The specimens were mechanically tested by pressure-controlled inflation with full-field deformation mapping using digital image correlation (DIC). The mechanical outcomes described the tissue tensile and viscoelastic behavior. Treatment with buffer alone increased the hydration of the posterior sclera compared to controls, while s-GAG removal caused a further increase in hydration compared to buffer-treated scleras. Buffer-treatment significantly changed the scleral mechanical behavior compared to the control condition, in a manner consistent with an increase in hydration. Specifically, buffer-treatment led to an increase in low-pressure stiffness, hysteresis, and creep rate, and a decrease in high-pressure stiffness. ChABC-treatment on buffer-treated scleras had opposite mechanical effects than buffer-treatment on controls, leading to a decrease in low-pressure stiffness, hysteresis, and creep rate, and an increase in high-pressure stiffness and transition strain. Furthermore, s-GAG digestion dramatically reduced the differences in the mechanical behavior among the 4 quadrants surrounding the ONH as well as the differences between the circumferential and meridional responses compared to the buffer-treated condition. These findings demonstrate a significant effect of s-GAGs on both the stiffness and time-dependent behavior of the sclera. Alterations in s-GAG content may contribute to the altered creep and stiffness of the sclera of myopic and glaucoma eyes.
Collapse
Affiliation(s)
- Barbara J Murienne
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA.
| | - Joan L Jefferys
- Glaucoma Center of Excellence, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Harry A Quigley
- Glaucoma Center of Excellence, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Thao D Nguyen
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA
| |
Collapse
|
44
|
Chiang SJ, Daimon M, Wang LH, Hung MJ, Chang NC, Lin HC. Association between mitral valve prolapse and open-angle glaucoma. Heart 2014; 101:609-15. [DOI: 10.1136/heartjnl-2014-306198] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
|
45
|
Abstract
During every heartbeat, cardiac valves open and close coordinately to control the unidirectional flow of blood. In this dynamically challenging environment, resident valve cells actively maintain homeostasis, but the signalling between cells and their microenvironment is complex. When homeostasis is disrupted and the valve opening obstructed, haemodynamic profiles can be altered and lead to impaired cardiac function. Currently, late stages of cardiac valve diseases are treated surgically, because no drug therapies exist to reverse or halt disease progression. Consequently, investigators have sought to understand the molecular and cellular mechanisms of valvular diseases using in vitro cell culture systems and biomaterial scaffolds that can mimic the extracellular microenvironment. In this Review, we describe how signals in the extracellular matrix regulate valve cell function. We propose that the cellular context is a critical factor when studying the molecular basis of valvular diseases in vitro, and one should consider how the surrounding matrix might influence cell signalling and functional outcomes in the valve. Investigators need to build a systems-level understanding of the complex signalling network involved in valve regulation, to facilitate drug target identification and promote in situ or ex vivo heart valve regeneration.
Collapse
|
46
|
Lee CH, Amini R, Gorman RC, Gorman JH, Sacks MS. An inverse modeling approach for stress estimation in mitral valve anterior leaflet valvuloplasty for in-vivo valvular biomaterial assessment. J Biomech 2014; 47:2055-63. [PMID: 24275434 PMCID: PMC4014535 DOI: 10.1016/j.jbiomech.2013.10.058] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/18/2013] [Accepted: 10/19/2013] [Indexed: 11/16/2022]
Abstract
Estimation of regional tissue stresses in the functioning heart valve remains an important goal in our understanding of normal valve function and in developing novel engineered tissue strategies for valvular repair and replacement. Methods to accurately estimate regional tissue stresses are thus needed for this purpose, and in particular to develop accurate, statistically informed means to validate computational models of valve function. Moreover, there exists no currently accepted method to evaluate engineered heart valve tissues and replacement heart valve biomaterials undergoing valvular stresses in blood contact. While we have utilized mitral valve anterior leaflet valvuloplasty as an experimental approach to address this limitation, robust computational techniques to estimate implant stresses are required. In the present study, we developed a novel numerical analysis approach for estimation of the in-vivo stresses of the central region of the mitral valve anterior leaflet (MVAL) delimited by a sonocrystal transducer array. The in-vivo material properties of the MVAL were simulated using an inverse FE modeling approach based on three pseudo-hyperelastic constitutive models: the neo-Hookean, exponential-type isotropic, and full collagen-fiber mapped transversely isotropic models. A series of numerical replications with varying structural configurations were developed by incorporating measured statistical variations in MVAL local preferred fiber directions and fiber splay. These model replications were then used to investigate how known variations in the valve tissue microstructure influence the estimated ROI stresses and its variation at each time point during a cardiac cycle. Simulations were also able to include estimates of the variation in tissue stresses for an individual specimen dataset over the cardiac cycle. Of the three material models, the transversely anisotropic model produced the most accurate results, with ROI averaged stresses at the fully-loaded state of 432.6±46.5 kPa and 241.4±40.5 kPa in the radial and circumferential directions, respectively. We conclude that the present approach can provide robust instantaneous mean and variation estimates of tissue stresses of the central regions of the MVAL.
Collapse
Affiliation(s)
- Chung-Hao Lee
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences (ICES), Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th Street, ACES 5.236, 1 University Station C0200, Austin, TX 78712, USA
| | - Rouzbeh Amini
- Department of Biomedical Engineering, The University of Akron, Auburn Science and Engineering Center 275, West Tower, Akron, OH 44325, USA
| | - Robert C Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, 3400 Civic Center Blvd, Philadelphia, PA 19104, USA
| | - Joseph H Gorman
- Gorman Cardiovascular Research Group, University of Pennsylvania, 3400 Civic Center Blvd, Philadelphia, PA 19104, USA
| | - Michael S Sacks
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences (ICES), Department of Biomedical Engineering, The University of Texas at Austin, 201 East 24th Street, ACES 5.236, 1 University Station C0200, Austin, TX 78712, USA.
| |
Collapse
|
47
|
Moroni F, Mirabella T. Decellularized matrices for cardiovascular tissue engineering. AMERICAN JOURNAL OF STEM CELLS 2014; 3:1-20. [PMID: 24660110 PMCID: PMC3960753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 02/06/2014] [Indexed: 06/03/2023]
Abstract
Cardiovascular disease (CVD) is one of the leading causes of death in the Western world. The replacement of damaged vessels and valves has been practiced since the 1950's. Synthetic grafts, usually made of bio-inert materials, are long-lasting and mechanically relevant, but fail when it comes to "biointegration". Decellularized matrices, instead, can be considered biological grafts capable of stimulating in vivo migration and proliferation of endothelial cells (ECs), recruitment and differentiation of mural cells, finally, culminating in the formation of a biointegrated tissue. Decellularization protocols employ osmotic shock, ionic and non-ionic detergents, proteolitic digestions and DNase/RNase treatments; most of them effectively eliminate the cellular component, but show limitations in preserving the native structure of the extracellular matrix (ECM). In this review, we examine the current state of the art relative to decellularization techniques and biological performance of decellularized heart, valves and big vessels. Furthermore, we focus on the relevance of ECM components, native and resulting from decellularization, in mediating in vivo host response and determining repair and regeneration, as opposed to graft corruption.
Collapse
|
48
|
Buchanan RM, Sacks MS. Interlayer micromechanics of the aortic heart valve leaflet. Biomech Model Mechanobiol 2013; 13:813-26. [PMID: 24292631 DOI: 10.1007/s10237-013-0536-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 10/09/2013] [Indexed: 10/26/2022]
Abstract
While the mechanical behaviors of the fibrosa and ventricularis layers of the aortic valve (AV) leaflet are understood, little information exists on their mechanical interactions mediated by the GAG-rich central spongiosa layer. Parametric simulations of the interlayer interactions of the AV leaflets in flexure utilized a tri-layered finite element (FE) model of circumferentially oriented tissue sections to investigate inter-layer sliding hypothesized to occur. Simulation results indicated that the leaflet tissue functions as a tightly bonded structure when the spongiosa effective modulus was at least 25 % that of the fibrosa and ventricularis layers. Novel studies that directly measured transmural strain in flexure of AV leaflet tissue specimens validated these findings. Interestingly, a smooth transmural strain distribution indicated that the layers of the leaflet indeed act as a bonded unit, consistent with our previous observations (Stella and Sacks in J Biomech Eng 129:757-766, 2007) of a large number of transverse collagen fibers interconnecting the fibrosa and ventricularis layers. Additionally, when the tri-layered FE model was refined to match the transmural deformations, a layer-specific bimodular material model (resulting in four total moduli) accurately matched the transmural strain and moment-curvature relations simultaneously. Collectively, these results provide evidence, contrary to previous assumptions, that the valve layers function as a bonded structure in the low-strain flexure deformation mode. Most likely, this results directly from the transverse collagen fibers that bind the layers together to disable physical sliding and maintain layer residual stresses. Further, the spongiosa may function as a general dampening layer while the AV leaflets deforms as a homogenous structure despite its heterogeneous architecture.
Collapse
Affiliation(s)
- Rachel M Buchanan
- Center for Cardiovascular Simulation, Institute for Computational Engineering and Sciences, Department of Biomedical Engineering, The University of Texas at Austin, Austin, USA
| | | |
Collapse
|
49
|
Connizzo BK, Sarver JJ, Birk DE, Soslowsky LJ, Iozzo RV. Effect of age and proteoglycan deficiency on collagen fiber re-alignment and mechanical properties in mouse supraspinatus tendon. J Biomech Eng 2013; 135:021019. [PMID: 23445064 DOI: 10.1115/1.4023234] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Collagen fiber realignment is one mechanism by which tendon responds to load. Re-alignment is altered when the structure of tendon is altered, such as in the natural process of aging or with alterations of matrix proteins, such as proteoglycan expression. While changes in re-alignment and mechanical properties have been investigated recently during development, they have not been studied in (1) aged tendons, or (2) in the absence of key proteoglycans. Collagen fiber re-alignment and the corresponding mechanical properties are quantified throughout tensile mechanical testing in both the insertion site and the midsubstance of mouse supraspinatus tendons in wild type (WT), decorin-null (Dcn(-/-)), and biglycan-null (Bgn(-/-)) mice at three different ages (90 days, 300 days, and 570 days). Percent relaxation was significantly decreased with age in the WT and Dcn(-/-) tendons, but not in the Bgn(-/-) tendons. Changes with age were found in the linear modulus at the insertion site where the 300 day group was greater than the 90 day and 570 day group in the Bgn(-/-) tendons and the 90 day group was smaller than the 300 day and 570 day groups in the Dcn(-/-) tendons. However, no changes in modulus were found across age in WT tendons were found. The midsubstance fibers of the WT and Bgn(-/-) tendons were initially less aligned with increasing age. The re-alignment was significantly altered with age in the WT tendons, with older groups responding to load later in the mechanical test. This was also seen in the Dcn(-/-) midsubstance and the Bgn(-/-) insertion, but not in the other locations. Although some studies have found changes in the WT mechanical properties with age, this study did not support those findings. However, it did show fiber re-alignment changes at both locations with age, suggesting a breakdown of tendon's ability to respond to load in later ages. In the proteoglycan-null tendons however, there were changes in the mechanical properties, accompanied only by location-dependent re-alignment changes, suggesting a site-specific role for these molecules in loading. Finally, changes in the mechanical properties did not occur in concert with changes in re-alignment, suggesting that typical mechanical property measurements alone are insufficient to describe how structural alterations affect tendon's response to load.
Collapse
Affiliation(s)
- Brianne K Connizzo
- McKay Orthopaedic Research Laboratory, University of Pennsylvania, 36th and Hamilton Walk, Philadelphia, PA 19104, USA
| | | | | | | | | |
Collapse
|
50
|
Tseng H, Kim EJ, Connell PS, Ayoub S, Shah JV, Grande-Allen KJ. The tensile and viscoelastic properties of aortic valve leaflets treated with a hyaluronidase gradient. Cardiovasc Eng Technol 2013; 4:151-160. [PMID: 38223558 PMCID: PMC10786346 DOI: 10.1007/s13239-013-0122-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Purpose When diseased, aortic valves are typically replaced with bioprosthetic heart valves (BPHVs), porcine valves or bovine pericardium that are fixed in glutaraldehyde. These replacements fail within 10-15 years due to calcification and fatigue, and their failure coincides with a loss of glycosaminoglycans (GAGs). This study investigates this relationship between GAG concentration and the tensile and viscoelastic properties of aortic valve leaflets. Methods Aortic valve leaflets were dissected from porcine hearts and digested in hyaluronidase in concentrations ranging from 0-5 U/mL for 0-24 hours, yielding a spectrum of GAG concentrations that was measured using the uronic acid assay and confirmed by Alcian Blue staining. Digested leaflets with varying GAG concentrations were then tested in tension in the circumferential and radial directions with varying strain rate, as well as in stress relaxation. Results The GAG concentration of the leaflets was successfully reduced using hyaluronidase, although water content was not affected. Elastic modulus, the maximum stress, and hysteresis significantly increased with decreasing GAG concentration. Extensibility and the radius of transition curvature did not change with GAG concentration. The stress relaxation behavior and strain-rate independent nature of the leaflet did not change with GAG concentration. Conclusions These results suggest that GAGs in the spongiosa lubricate tissue motion and reduce stresses experienced by the leaflet. This study forms the basis for predictive models of BPHV mechanics based on GAG concentration, and guides the rational design of future heart valve replacements.
Collapse
Affiliation(s)
- Hubert Tseng
- Department of Bioengineering, Rice University, Houston, TX USA
| | - Eric J. Kim
- Department of Bioengineering, Rice University, Houston, TX USA
| | - Patrick S. Connell
- Department of Bioengineering, Rice University, Houston, TX USA
- Baylor College of Medicine, Houston, TX USA
| | - Salma Ayoub
- Department of Bioengineering, Rice University, Houston, TX USA
| | - Jay V. Shah
- Department of Bioengineering, Rice University, Houston, TX USA
| | | |
Collapse
|