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Conci C, Sironi L, Jacchetti E, Panzeri D, Inverso D, Martínez Vázquez R, Osellame R, Collini M, Cerullo G, Chirico G, Raimondi MT. In vivo label-free tissue histology through a microstructured imaging window. APL Bioeng 2024; 8:016102. [PMID: 38222895 PMCID: PMC10787586 DOI: 10.1063/5.0165411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 11/06/2023] [Indexed: 01/16/2024] Open
Abstract
Tissue histopathology, based on hematoxylin and eosin (H&E) staining of thin tissue slices, is the gold standard for the evaluation of the immune reaction to the implant of a biomaterial. It is based on lengthy and costly procedures that do not allow longitudinal studies. The use of non-linear excitation microscopy in vivo, largely label-free, has the potential to overcome these limitations. With this purpose, we develop and validate an implantable microstructured device for the non-linear excitation microscopy assessment of the immune reaction to an implanted biomaterial label-free. The microstructured device, shaped as a matrix of regular 3D lattices, is obtained by two-photon laser polymerization. It is subsequently implanted in the chorioallantoic membrane (CAM) of embryonated chicken eggs for 7 days to act as an intrinsic 3D reference frame for cell counting and identification. The histological analysis based on H&E images of the tissue sections sampled around the implanted microstructures is compared to non-linear excitation and confocal images to build a cell atlas that correlates the histological observations to the label-free images. In this way, we can quantify the number of cells recruited in the tissue reconstituted in the microstructures and identify granulocytes on label-free images within and outside the microstructures. Collagen and microvessels are also identified by means of second-harmonic generation and autofluorescence imaging. The analysis indicates that the tissue reaction to implanted microstructures is like the one typical of CAM healing after injury, without a massive foreign body reaction. This opens the path to the use of similar microstructures coupled to a biomaterial, to image in vivo the regenerating interface between a tissue and a biomaterial with label-free non-linear excitation microscopy. This promises to be a transformative approach, alternative to conventional histopathology, for the bioengineering and the validation of biomaterials in in vivo longitudinal studies.
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Affiliation(s)
- Claudio Conci
- Department of Chemistry, Materials and Chemical Engineering “Giulio Natta,” Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milan, Italy
| | - Laura Sironi
- Department of Physics, Università di Milano-Bicocca, Piazza della Scienza 3, 20126 Milan, Italy
| | - Emanuela Jacchetti
- Department of Chemistry, Materials and Chemical Engineering “Giulio Natta,” Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milan, Italy
| | - Davide Panzeri
- Department of Physics, Università di Milano-Bicocca, Piazza della Scienza 3, 20126 Milan, Italy
| | - Donato Inverso
- Division of Immunology, Transplantation and Infectious Diseases IRCCS San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy
| | - Rebeca Martínez Vázquez
- Institute for Photonics and Nanotechnologies (IFN), CNR and Department of Physics, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milan, Italy
| | - Roberto Osellame
- Institute for Photonics and Nanotechnologies (IFN), CNR and Department of Physics, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milan, Italy
| | - Maddalena Collini
- Department of Physics, Università di Milano-Bicocca, Piazza della Scienza 3, 20126 Milan, Italy
| | - Giulio Cerullo
- Institute for Photonics and Nanotechnologies (IFN), CNR and Department of Physics, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milan, Italy
| | - Giuseppe Chirico
- Department of Physics, Università di Milano-Bicocca, Piazza della Scienza 3, 20126 Milan, Italy
| | - Manuela Teresa Raimondi
- Department of Chemistry, Materials and Chemical Engineering “Giulio Natta,” Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milan, Italy
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Wu W, Ching S, Sabin P, Laurence DW, Maas SA, Lasso A, Weiss JA, Jolley MA. The effects of leaflet material properties on the simulated function of regurgitant mitral valves. J Mech Behav Biomed Mater 2023; 142:105858. [PMID: 37099920 PMCID: PMC10199327 DOI: 10.1016/j.jmbbm.2023.105858] [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: 02/09/2023] [Revised: 03/30/2023] [Accepted: 04/12/2023] [Indexed: 04/28/2023]
Abstract
Advances in three-dimensional imaging provide the ability to construct and analyze finite element (FE) models to evaluate the biomechanical behavior and function of atrioventricular valves. However, while obtaining patient-specific valve geometry is now possible, non-invasive measurement of patient-specific leaflet material properties remains nearly impossible. Both valve geometry and tissue properties play a significant role in governing valve dynamics, leading to the central question of whether clinically relevant insights can be attained from FE analysis of atrioventricular valves without precise knowledge of tissue properties. As such we investigated (1) the influence of tissue extensibility and (2) the effects of constitutive model parameters and leaflet thickness on simulated valve function and mechanics. We compared metrics of valve function (e.g., leaflet coaptation and regurgitant orifice area) and mechanics (e.g., stress and strain) across one normal and three regurgitant mitral valve (MV) models with common mechanisms of regurgitation (annular dilation, leaflet prolapse, leaflet tethering) of both moderate and severe degree. We developed a novel fully-automated approach to accurately quantify regurgitant orifice areas of complex valve geometries. We found that the relative ordering of the mechanical and functional metrics was maintained across a group of valves using material properties up to 15% softer than the representative adult mitral constitutive model. Our findings suggest that FE simulations can be used to qualitatively compare how differences and alterations in valve structure affect relative atrioventricular valve function even in populations where material properties are not precisely known.
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Affiliation(s)
- Wensi Wu
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, 19104, PA, USA; Division of Pediatric Cardiology, Children's Hospital of Philadelphia, Philadelphia, 19104, PA, USA
| | - Stephen Ching
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, 19104, PA, USA
| | - Patricia Sabin
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, 19104, PA, USA
| | - Devin W Laurence
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, 19104, PA, USA; Division of Pediatric Cardiology, Children's Hospital of Philadelphia, Philadelphia, 19104, PA, USA
| | - Steve A Maas
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112, UT, USA; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT 84112, UT, USA
| | - Andras Lasso
- Laboratory for Percutaneous Surgery, Queen's University, Kingston, ON, Canada
| | - Jeffrey A Weiss
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112, UT, USA; Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT 84112, UT, USA
| | - Matthew A Jolley
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, 19104, PA, USA; Division of Pediatric Cardiology, Children's Hospital of Philadelphia, Philadelphia, 19104, PA, USA.
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Silva H, Tassone C, Ross EG, Lee JT, Zhou W, Nelson D. Collagen Fibril Orientation in Tissue Specimens From Atherosclerotic Plaque Explored Using Small Angle X-Ray Scattering. J Biomech Eng 2022; 144:024505. [PMID: 34529040 PMCID: PMC10782870 DOI: 10.1115/1.4052432] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 08/22/2021] [Indexed: 01/12/2023]
Abstract
Atherosclerotic plaques can gradually develop in certain arteries. Disruption of fibrous tissue in plaques can result in plaque rupture and thromboembolism, leading to heart attacks and strokes. Collagen fibrils are important tissue building blocks and tissue strength depends on how fibrils are oriented. Fibril orientation in plaque tissue may potentially influence vulnerability to disruption. While X-ray scattering has previously been used to characterize fibril orientations in soft tissues and bones, it has never been used for characterization of human atherosclerotic plaque tissue. This study served to explore fibril orientation in specimens from human plaques using small angle X-ray scattering (SAXS). Plaque tissue was extracted from human femoral and carotid arteries, and each tissue specimen contained a region of calcified material. Three-dimensional (3D) collagen fibril orientation was determined along scan lines that started away from and then extended toward a given calcification. Fibrils were found to be oriented mainly in the circumferential direction of the plaque tissue at the majority of locations away from calcifications. However, in a number of cases, the dominant fibril direction differed near a calcification, changing from circumferential to longitudinal or thickness (radial) directions. Further study is needed to elucidate how these fibril orientations may influence plaque tissue stress-strain behavior and vulnerability to rupture.
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Affiliation(s)
- Herbert Silva
- NASA, 2101 NASA Parkway Building 13 R 208, Houston, TX 77058
| | - Christopher Tassone
- Stanford Synchrotron Radiation Lightsource, 2575 Sand Hill Road, Menlo Park, CA 94025
| | - Elsie Gyang Ross
- Division of Vascular Surgery, Stanford Medical Center, 300 Pasteur Drive, Stanford, CA 94305
| | - Jason T. Lee
- Division of Vascular Surgery, Stanford Medical Center, 300 Pasteur Drive, Stanford, CA 94305
| | - Wei Zhou
- Vascular Surgery Division, College of Medicine, University of Arizona, Tucson, AZ 85724
| | - Drew Nelson
- Mechanical Engineering Department, Stanford University, Stanford, CA 94305
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Jana S, Morse D, Lerman A. Leaflet Tissue Generation from Microfibrous Heart Valve Leaflet Scaffolds with Native Characteristics. ACS APPLIED BIO MATERIALS 2021; 4:7836-7847. [PMID: 35006765 DOI: 10.1021/acsabm.1c00768] [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] [Indexed: 11/29/2022]
Abstract
Mechanical and bioprosthetic valves that are currently applied for replacing diseased heart valves are not fully efficient. Heart valve tissue engineering may solve the issues faced by the prosthetic valves in heart valve replacement. The leaflets of native heart valves have a trilayered structure with layer-specific orientations; thus, it is imperative to develop functional leaflet tissue constructs with a native trilayered, oriented structure. Its key solution is to develop leaflet scaffolds with a native morphology and structure. In this study, microfibrous leaflet scaffolds with a native trilayered and oriented structure were developed in an electrospinning system. The scaffolds were implanted for 3 months in rats subcutaneously to study the scaffold efficiencies in generating functional tissue-engineered leaflet constructs. These in vivo tissue-engineered leaflet constructs had a trilayered, oriented structure similar to native leaflets. The tensile properties of constructs indicated that they were able to endure the hydrodynamic load of the native heart valve. Collagen, glycosaminoglycans, and elastin─the predominant extracellular matrix components of native leaflets─were found sufficiently in the leaflet tissue constructs. The residing cells in the leaflet tissue constructs showed vimentin and α-smooth muscle actin expression, i.e., the constructs were in a growing state. Thus, the trilayered, oriented fibrous leaflet scaffolds produced in this study could be useful to develop heart valve scaffolds for successful heart valve replacements.
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Affiliation(s)
- Soumen Jana
- Department of Bioengineering, University of Missouri, Columbia, Missouri 65211, United States.,Division of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, United States
| | - David Morse
- Division of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, United States
| | - Amir Lerman
- Division of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, United States
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Ross CJ, Laurence DW, Echols AL, Babu AR, Gu T, Duginski GA, Johns CH, Mullins BT, Casey KM, Laurence KA, Zhao YD, Amini R, Fung KM, Mir A, Burkhart HM, Wu Y, Holzapfel GA, Lee CH. Effects of enzyme-based removal of collagen and elastin constituents on the biaxial mechanical responses of porcine atrioventricular heart valve anterior leaflets. Acta Biomater 2021; 135:425-440. [PMID: 34481053 DOI: 10.1016/j.actbio.2021.08.043] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 08/22/2021] [Accepted: 08/26/2021] [Indexed: 12/24/2022]
Abstract
The leaflets of the atrioventricular heart valves (AHVs) regulate the one-directional flow of blood through a coordination of the extracellular matrix components, including the collagen fibers, elastin, and glycosaminoglycans. Dysfunction of the AHVs, such as those caused by unfavorable microstructural remodeling, lead to valvular heart diseases and improper blood flow, which can ultimately cause heart failure. In order to better understand the mechanics and remodeling of the AHV leaflets and how therapeutics can inadvertently cause adverse microstructural changes, a systematic characterization of the role of each constituent in the biomechanical properties is appropriate. Previous studies have quantified the contributions of the individual microstructural components to tissue-level behavior for the semilunar valve cusps, but not for the AHV leaflets. In this study, for the first time, we quantify the relationships between microstructure and mechanics of the AHV leaflet using a three-step experimental procedure: (i) biaxial tension and stress relaxation testing of control (untreated) porcine AHV anterior leaflet specimens; (ii) enzyme treatment to remove a portion of either the collagen or elastin constituent; and (iii) biaxial tensile and stress relaxation testing of the constituent-removed (treated) specimens. We have observed that the removal of ∼100% elastin resulted in a ∼10% decrease in the tissue extensibility with biaxial tension and a ∼10% increase in the overall stress reduction with stress relaxation. In contrast, removal of 46% of the collagen content insignificantly affected tissue extensibility with biaxial tension and significantly increased stress decay (10%) with stress relaxation. These findings provide an insight into the microstructure-mechanics relationship of the AHVs and will be beneficial for future developments and refinements of microstructurally informed constitutive models for the simulation of diseased and surgically intervened AHV function. STATEMENT OF SIGNIFICANCE: This study presents, for the first time, a thorough mechanical characterization of the atrioventricular heart valve leaflets before and after enzymatic removal of elastin and collagen. We found that the biaxial tensile properties of elastin-deficient tissues and collagen-deficient are stiffer. The fact of elastin supporting low-stress valve function and collagen as the main load-bearing component was evident in a decrease in the low-tension modulus for elastin-deficient tissues and in the high-tension modulus for collagen-deficient tissues. Our quantification and experimental technique could be useful in predicting the disease-related changes in heart valve mechanics. The information obtained from this work is valuable for refining the constitutive models that describe the essential microstructure-mechanics relationship.
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Campion G, Hershberger K, Whelan A, Conroy J, Lally C, Murphy BP. A Biomechanical and Microstructural Analysis of Bovine and Porcine Pericardium for Use in Bioprosthetic Heart Valves. STRUCTURAL HEART 2021. [DOI: 10.1080/24748706.2021.1938317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Stieglmeier F, Grab M, König F, Büch J, Hagl C, Thierfelder N. Mapping of bovine pericardium to enable a standardized acquirement of material for medical implants. J Mech Behav Biomed Mater 2021; 118:104432. [PMID: 33853036 DOI: 10.1016/j.jmbbm.2021.104432] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 02/21/2021] [Accepted: 02/26/2021] [Indexed: 02/06/2023]
Abstract
OBJECTIVES Bovine pericardium - native, fixed as well as decellularized - is one of the most common implant materials in modern cardiovascular surgery. Although used in everyday procedures, there are no recommendations in regard to which part of the pericardium to prefer. It was the aim of this study, to identify areas of the pericardium with consistent properties and high durability. METHODS Fresh bovine pericardia were collected from a local slaughterhouse. The native pericardia were analyzed at 140 spots in regard to thickness and fiber orientation. Based on these results, five promising areas were selected for further evaluation. The pericardia were decellularized with detergents (0.5% sodiumdesoxycholate/0.5% sodiumdodecylsulfate) and subsequently incubated in DNAse. The two investigation groups native und DC consisted of 20 samples each. The efficiency of the decellularization was evaluated by DNA quantification, as well as DAPI and H&E staining. Biomechanical properties were determined using uniaxial tensile tests. To evaluate the microstructure, scanning electron microscopy, Picrosirius Red- and Movat's Pentachrome staining were utilized. To assess the long-term durability, patches were tested in a high-cycle system for a duration equaling the stress of three months in-vivo. Commercially available, fixed pericardium patches served as control group. RESULTS Only a limited part of the pericardium showed a homogenous and usable thickness. The decellularization removed all cell nuclei, proven by negative DAPI and H&E staining, and also significantly reduced the DNA amount by 84%. The mechanical testing revealed that two investigated areas had an inconsistent tensile strength. Microscopical observations showed that the integrity of the extracellular matrix did not suffer by the decellularization procedure. During the long-term testing, most of the pericardia slowly lost tautness, though none of them got measurably damaged. Especially one area showed no decline of tensile strength after durability testing at all. Decellularized patches and fixed patches achieved comparable results in mechanical testing and microscopical evaluation after the durability testing. CONCLUSION We could clearly document significant, location-based differences within single pericardia. Only one area showed consistent properties and a high durability. We highly recommend taking this into account for future implant material selections.
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Affiliation(s)
- Felix Stieglmeier
- Laboratory for Cardiovascular Tissue Engineering, Department of Cardiac Surgery, Ludwig - Maximilian University Munich, Germany.
| | - Maximilian Grab
- Laboratory for Cardiovascular Tissue Engineering, Department of Cardiac Surgery, Ludwig - Maximilian University Munich, Germany
| | - Fabian König
- Laboratory for Cardiovascular Tissue Engineering, Department of Cardiac Surgery, Ludwig - Maximilian University Munich, Germany
| | - Joscha Büch
- Laboratory for Cardiovascular Tissue Engineering, Department of Cardiac Surgery, Ludwig - Maximilian University Munich, Germany
| | - Christian Hagl
- Laboratory for Cardiovascular Tissue Engineering, Department of Cardiac Surgery, Ludwig - Maximilian University Munich, Germany
| | - Nikolaus Thierfelder
- Laboratory for Cardiovascular Tissue Engineering, Department of Cardiac Surgery, Ludwig - Maximilian University Munich, Germany
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Witte M, Jaspers S, Wenck H, Rübhausen M, Fischer F. General method for classification of fiber families in fiber-reinforced materials: application to in-vivo human skin images. Sci Rep 2020; 10:10888. [PMID: 32616723 PMCID: PMC7331592 DOI: 10.1038/s41598-020-67632-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 06/04/2020] [Indexed: 11/17/2022] Open
Abstract
Fiber structures play a major role for the function of fiber-reinforced materials such as biological tissue. An objective classification of the fiber orientations into fiber families is crucial to understand its mechanical properties. We introduce the Fiber Image Network Evaluation Algorithm (FINE algorithm) to classify and quantify the number of fiber families in scientific images. Each fiber family is characterized by an amplitude, a mean orientation, and a dispersion. A new alignment index giving the averaged fraction of aligned fibers is defined. The FINE algorithm is validated by realistic grayscale Monte-Carlo fiber images. We apply the algorithm to an in-vivo depth scan of second harmonic generation images of dermal collagen in human skin. The derived alignment index exhibits a crossover at a critical depth where two fiber families with a perpendicular orientation around the main tension line arise. This strongly suggests the presence of a transition from the papillary to the reticular dermis. Hence, the FINE algorithm provides a valuable tool for a reliable classification and a meaningful interpretation of in-vivo collagen fiber networks and general fiber reinforced materials.
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Affiliation(s)
- Maximilian Witte
- Center for Free-Electron Laser Science (CFEL), University of Hamburg, 22607, Hamburg, Germany
- Beiersdorf AG, 20245, Hamburg, Germany
| | | | | | - Michael Rübhausen
- Center for Free-Electron Laser Science (CFEL), University of Hamburg, 22607, Hamburg, Germany
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Jett SV, Hudson LT, Baumwart R, Bohnstedt BN, Mir A, Burkhart HM, Holzapfel GA, Wu Y, Lee CH. Integration of polarized spatial frequency domain imaging (pSFDI) with a biaxial mechanical testing system for quantification of load-dependent collagen architecture in soft collagenous tissues. Acta Biomater 2020; 102:149-168. [PMID: 31734412 PMCID: PMC8101699 DOI: 10.1016/j.actbio.2019.11.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Revised: 11/11/2019] [Accepted: 11/12/2019] [Indexed: 12/30/2022]
Abstract
Collagen fiber networks provide the structural strength of tissues, such as tendons, skin and arteries. Quantifying the fiber architecture in response to mechanical loads is essential towards a better understanding of the tissue-level mechanical behaviors, especially in assessing disease-driven functional changes. To enable novel investigations into these load-dependent fiber structures, a polarized spatial frequency domain imaging (pSFDI) device was developed and, for the first time, integrated with a biaxial mechanical testing system. The integrated instrument is capable of a wide-field quantification of the fiber orientation and the degree of optical anisotropy (DOA), representing the local degree of fiber alignment. The opto-mechanical instrument''s performance was assessed through uniaxial loading on tendon tissues with known collagen fiber microstructures. Our results revealed that the bulk fiber orientation angle of the tendon tissue changed minimally with loading (median ± 0.5*IQR of 52.7° ± 3.3° and 51.9° ± 3.3° under 0 and 3% longitudinal strains, respectively), whereas on a micro-scale, the fibers became better aligned with the direction of loading: the DOA (mean ± SD) increased from 0.149 ± 0.032 to 0.198 ± 0.056 under 0 and 3% longitudinal strains, respectively, p < 0.001. The integrated instrument was further applied to study two representative mitral valve anterior leaflet (MVAL) tissues subjected to various biaxial loads. The fiber orientations within these representative MVAL tissue specimens demonstrated noticeable heterogeneity, with the local fiber orientations dependent upon the sample, the spatial and transmural locations, and the applied loading. Our results also showed that fibers were generally better aligned under equibiaxial (DOA = 0.089 ± 0.036) and circumferentially-dominant loading (DOA = 0.086 ± 0.037) than under the radially-dominant loading (DOA = 0.077 ± 0.034), indicating circumferential predisposition. These novel findings exemplify a deeper understanding of the load-dependent collagen fiber microstructures obtained through the use of the integrated opto-mechanical instrument. STATEMENT OF SIGNIFICANCE: In this study, a novel quantitative opto-mechanical system was developed by combining a polarized Spatial Frequency Domain Imaging (pSFDI) device with a biaxial mechanical tester. The integrated system was used to quantify the load-dependent collagen fiber microstructures in representative tendon and mitral valve anterior leaflet (MVAL) tissues. Our results revealed that MVAL's fiber architectures exhibited load-dependent spatial and transmural heterogeneities, suggesting further microstructural complexity than previously reported in heart valve tissues. These novel findings were possible through the system's ability to, for the first time, capture the load-dependent collagen architecture in the mitral valve anterior leaflet tissue over a wide field of view (e.g., 10 × 10 mm for the MVAL tissue specimens). Such capabilities afford unique future opportunities to improve patient outcomes through concurrent mechanical and microstructural assessments of healthy and diseased tissues in conditions such as heart valve regurgitation and calcification.
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Affiliation(s)
- Samuel V Jett
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, Affiliated Faculty Member, Institute for Biomedical Engineering, Science, and Technology, The University of Oklahoma, 865 Asp Ave., Felgar Hall Rm. 219C, Norman, OK 73019-3609, United States
| | - Luke T Hudson
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, Affiliated Faculty Member, Institute for Biomedical Engineering, Science, and Technology, The University of Oklahoma, 865 Asp Ave., Felgar Hall Rm. 219C, Norman, OK 73019-3609, United States
| | - Ryan Baumwart
- Center for Veterinary Health Sciences, Oklahoma State University, 2065 W. Farm Rd., Stillwater, OK 74078, United States
| | - Bradley N Bohnstedt
- Department of Neurosurgery, The University of Oklahoma Health Sciences Center, 1000 N Lincoln Blvd #400, Oklahoma City, OK 73104, United States
| | - Arshid Mir
- Division of Pediatric Cardiology, Department of Pediatrics, The University of Oklahoma Health Sciences Center, 1200 Children's Ave., Suite 2F, Oklahoma City, OK 73104, United States
| | - Harold M Burkhart
- Division of Cardiothoracic Surgery, Department of Surgery, The University of Oklahoma Health Sciences Center, 800 Stanton L. Young Blvd. Suite 9000, Oklahoma City, OK 73104, United States
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16/2 8010 Graz, Austria; Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
| | - Yi Wu
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, Affiliated Faculty Member, Institute for Biomedical Engineering, Science, and Technology, The University of Oklahoma, 865 Asp Ave., Felgar Hall Rm. 219C, Norman, OK 73019-3609, United States
| | - Chung-Hao Lee
- Biomechanics and Biomaterials Design Laboratory, School of Aerospace and Mechanical Engineering, Affiliated Faculty Member, Institute for Biomedical Engineering, Science, and Technology, The University of Oklahoma, 865 Asp Ave., Felgar Hall Rm. 219C, Norman, OK 73019-3609, United States; Institute for Biomedical Engineering, Science and Technology, The University of Oklahoma, 202 West Boyd St., Norman, OK 73019, United States.
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Rassoli A, Li Y, Bao X, Kawecki F, Zhao X, Chappard D, Le-Bel G, Feng J, Weber B, Fatouraee N, Zhang Z, Jing Z, Germain L, Wang L, Guidoin R. Donkey pericardium as a select sourcing to manufacture percutaneous heart valves: Decellularization has not yet demonstrated any clear cut advantage to glutaraldehyde treatment. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2019. [DOI: 10.1016/j.medntd.2020.100029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Joyce K, Rochev Y, Rahmani S. Assessment of the uniaxial experimental parameters utilised for the mechanical testing of bovine pericardium. J Mech Behav Biomed Mater 2019; 96:27-37. [DOI: 10.1016/j.jmbbm.2019.04.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 04/09/2019] [Accepted: 04/13/2019] [Indexed: 11/26/2022]
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Porcine versus bovine bioprosthetic valves in mitral position: does choice really matter? Indian J Thorac Cardiovasc Surg 2019; 36:105-113. [PMID: 33061108 DOI: 10.1007/s12055-019-00847-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 05/26/2019] [Accepted: 06/13/2019] [Indexed: 10/26/2022] Open
Abstract
Background Bioprosthetic valves are increasingly used for surgical mitral valve replacement (MVR). The long-term outcomes of bovine (BoMVR) vs porcine (PoMVR) remain an enigma regarding the durability. This study aims to examine the outcomes of BoMVR vs PoMVR. Methods A retrospective analysis of all bioprosthetic MVRs, with concomitant procedures, at a single tertiary referral institution from January 2005 to December 2008 was conducted. Procedures were classified as BoMVR or PoMVR. The age group was from 40 to 70 years. Results We identified 154 BoMVR patients and 120 PoMVR patients after matching the two groups with respect to age, sex, valve size and concomitant procedures. Kaplan-Meier survival analysis model was used for corresponding statistical analysis. Freedom from reoperation (all cause), freedom from non-structural valve deterioration, freedom from structural valve deterioration, freedom from heart failure and freedom from infective endocarditis were 96.4 ± 0.08, 97.1 ± 0.07, 96.4 ± 0.08%, 98.2 ± 0.07, and 98.6 ± 0.06% in PoMVR, respectively, and 92.6 ± 0.09, 91.6 ± 0.08, 90.6 ± 0.09, 94 ± 0.08, and 92.8 ± 0.08% in BoMVR groups, respectively, at the end of 10-year follow-up (mean follow up of 6.2 ± 2.3 years). Overall, 20 (12.9%) patients were lost to follow-up in the BoMVR and 15(12.5%) patients in the PoMVR groups for a global follow-up of 87.1%. Conclusions For patients undergoing MVR with a bioprosthetic valve, the choice of PoMVR vs BoMVR favours more in favour of PoMVR as evidenced by the outcome results. Probably long-term follow-up with more patients might throw further light on the debatable topic.
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Anssari-Benam A, Screen HR, Bucchi A. Insights into the micromechanics of stress-relaxation and creep behaviours in the aortic valve. J Mech Behav Biomed Mater 2019; 93:230-245. [DOI: 10.1016/j.jmbbm.2019.02.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 10/30/2018] [Accepted: 02/11/2019] [Indexed: 12/20/2022]
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14
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TAVR-present, future, and challenges in developing countries. Indian J Thorac Cardiovasc Surg 2019; 35:473-484. [PMID: 33061033 DOI: 10.1007/s12055-018-00786-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 12/10/2018] [Accepted: 12/19/2018] [Indexed: 12/25/2022] Open
Abstract
Transcatheter aortic valve replacement (TAVR) has become a well-established therapy for inoperable and high-risk patients of Aortic Stenosis in most of the part of the world. The technological advancements in the hemodynamic performance and design of valve prosthesis and also the data provided by various trials regarding the safety and efficacy of TAVR have widened the scope of TAVR in intermediate and low-risk groups also. The main focus of this review is to discuss the feasibility of TAVR in developing countries. Along with this review, it also gives a detailed outlook of the pros and cons of TAVR along with insight into the future of TAVR and its adoption into the low-risk group.
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15
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Coyan GN, D'Amore A, Matsumura Y, Pedersen DD, Luketich SK, Shanov V, Katz WE, David TE, Wagner WR, Badhwar V. In vivo functional assessment of a novel degradable metal and elastomeric scaffold-based tissue engineered heart valve. J Thorac Cardiovasc Surg 2018; 157:1809-1816. [PMID: 30578064 DOI: 10.1016/j.jtcvs.2018.09.128] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 09/01/2018] [Accepted: 09/22/2018] [Indexed: 01/08/2023]
Abstract
OBJECTIVE Ideal heart valve solutions aim to provide thrombosis-free durability. A scaffold-based polycarbonate urethane urea tissue-engineered heart valve designed to mimic native valve microstructure and function was used. This study examined the acute in vivo function of a stented tissue-engineered heart valve in a porcine model. METHODS Trileaflet valves were fabricated by electrospinning polycarbonate urethane urea using double component fiber deposition. The tissue-engineered heart valve was mounted on an AZ31 magnesium alloy biodegradable stent frame. Five 80-kg Yorkshire pigs underwent open tissue-engineered heart valve implantation on cardiopulmonary bypass in the pulmonary position. Tissue-engineered heart valve function was echocardiographically evaluated immediately postimplant and at planned study end points at 1, 4, 8, and 12 hours. Explanted valves underwent biaxial mechanical testing and scanning electron microscopy for ultrastructural analysis and thrombosis detection. RESULTS All 5 animals underwent successful valve implantation. All were weaned from cardiopulmonary bypass, closed, and recovered until harvest study end point except 1 animal that was found to have congenital tricuspid valve dysplasia and that was euthanized postimplant. All 5 cases revealed postcardiopulmonary bypass normal leaflet function, no regurgitation, and an average peak velocity of 2 m/s, unchanged at end point. All tissue-engineered heart valve leaflets retained microstructural architecture with no platelet activation or thrombosis by scanning electron microscopy. There was microscopic evidence of fibrin deposition on 2 of 5 stent frames, not on the tissue-engineered heart valve. Biaxial stress examination revealed retained postimplant mechanics of tissue-engineered heart valve fibers without functional or ultrastructural degradation. CONCLUSIONS A biodegradable elastomeric heart valve scaffold for in situ tissue-engineered leaflet replacement is acutely functional and devoid of leaflet microthrombosis.
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Affiliation(s)
- Garrett N Coyan
- Department of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, Pa; McGowan Institute for Regenerative Medicine, Pittsburgh, Pa
| | - Antonio D'Amore
- Department of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, Pa; McGowan Institute for Regenerative Medicine, Pittsburgh, Pa; Fondazione RiMED, Palermo, Italy
| | - Yasumoto Matsumura
- Department of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, Pa; McGowan Institute for Regenerative Medicine, Pittsburgh, Pa
| | - Drake D Pedersen
- Department of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, Pa; McGowan Institute for Regenerative Medicine, Pittsburgh, Pa
| | - Samuel K Luketich
- Department of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, Pa; McGowan Institute for Regenerative Medicine, Pittsburgh, Pa
| | - Vesselin Shanov
- Department of Bioengineering, University of Cincinnati, Cincinnati, Ohio
| | - William E Katz
- Division of Cardiology, University of Pittsburgh, Pittsburgh, Pa
| | - Tirone E David
- Division of Cardiac Surgery, Toronto General Hospital, Toronto, Ontario, Canada
| | - William R Wagner
- Department of Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, Pa; McGowan Institute for Regenerative Medicine, Pittsburgh, Pa
| | - Vinay Badhwar
- McGowan Institute for Regenerative Medicine, Pittsburgh, Pa; Department of Cardiovascular and Thoracic Surgery, West Virginia University, Morgantown, WVa.
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16
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Cuando-Espitia N, Sánchez-Arévalo F, Hernández-Cordero J. Random laser imaging of bovine pericardium under the uniaxial tensile test. BIOMEDICAL OPTICS EXPRESS 2018; 9:3523-3533. [PMID: 30338137 PMCID: PMC6191640 DOI: 10.1364/boe.9.003523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 06/21/2018] [Accepted: 06/25/2018] [Indexed: 06/08/2023]
Abstract
We demonstrate random laser (RL) emission from within bovine pericardium (BP) tissue. The interest in BP relies on its wide use as a valve replacement and as a biological patch. By imaging the emitting tissue, we show that RL emission is mostly generated inside the collagen fibers. Multimode RL operation is thus achieved within the volume of each fiber. Image analysis reveals that the intensity of the RL emission from individual fibers is dependent on the relative orientation to the stress axis. Our results suggest that RL intensity may be used as an indicator of stress concentration in individual fibers.
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Affiliation(s)
- Natanael Cuando-Espitia
- Department of Mechanical Engineering, University of California Riverside, Riverside, CA 92521, USA
| | - Francisco Sánchez-Arévalo
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, A.P. 70-360, Cd. Universitaria, México D.F. 04510, México
| | - Juan Hernández-Cordero
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, A.P. 70-360, Cd. Universitaria, México D.F. 04510, México
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17
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Hasan A, Soliman S, El Hajj F, Tseng YT, Yalcin HC, Marei HE. Fabrication and In Vitro Characterization of a Tissue Engineered PCL-PLLA Heart Valve. Sci Rep 2018; 8:8187. [PMID: 29844329 PMCID: PMC5974353 DOI: 10.1038/s41598-018-26452-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 04/25/2018] [Indexed: 11/25/2022] Open
Abstract
Heart valve diseases are among the leading causes of cardiac failure around the globe. Nearly 90,000 heart valve replacements occur in the USA annually. Currently, available options for heart valve replacement include bioprosthetic and mechanical valves, both of which have severe limitations. Bioprosthetic valves can last for only 10-20 years while patients with mechanical valves always require blood-thinning medications throughout the remainder of the patient's life. Tissue engineering has emerged as a promising solution for the development of a viable, biocompatible and durable heart valve; however, a human implantable tissue engineered heart valve is yet to be achieved. In this study, a tri-leaflet heart valve structure is developed using electrospun polycaprolactone (PCL) and poly L-lactic acid (PLLA) scaffolds, and a set of in vitro testing protocol has been developed for routine manufacturing of tissue engineered heart valves. Stress-strain curves were obtained for mechanical characterization of different valves. The performances of the developed valves were hemodynamically tested using a pulse duplicator, and an echocardiography machine. Results confirmed the superiority of the PCL-PLLA heart valve compared to pure PCL or pure PLLA. The developed in vitro test protocol involving pulse duplicator and echocardiography tests have enormous potential for routine application in tissue engineering of heart valves.
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Affiliation(s)
- Anwarul Hasan
- Department of Mechanical and Industrial Engineering, College of Engineering, Qatar University, Doha, Qatar.
| | | | - Fatima El Hajj
- Biomedical Engineering, Faculty of Engineering and Architecture, American University of Beirut, Beirut, 11-0236, Lebanon
| | - Yuan-Tsan Tseng
- Division of Qatar Cardiovascular Research Center, Sidra Medicine, Doha, Qatar
- Imperial College, NHLI, Heart Science Centre, Harefield, Middlesex, UB9 6JH, United Kingdom
| | - Huseyin C Yalcin
- Biomedical Research Center, Qatar University, Doha, PO Box 2713, Qatar
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18
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Zhang S, Zarei V, Winkelstein BA, Barocas VH. Multiscale mechanics of the cervical facet capsular ligament, with particular emphasis on anomalous fiber realignment prior to tissue failure. Biomech Model Mechanobiol 2018; 17:133-145. [PMID: 28821971 PMCID: PMC5809183 DOI: 10.1007/s10237-017-0949-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 08/04/2017] [Indexed: 12/11/2022]
Abstract
The facet capsular ligaments encapsulate the bilateral spinal facet joints and are common sources of painful injury due to afferent innervation. These ligaments exhibit architectural complexity, which is suspected to contribute to the experimentally observed lack of co-localization between macroscopic strain and microstructural tissue damage. The heterogeneous and multiscale nature of this ligament, combined with challenges in experimentally measuring its microscale mechanics, hinders the ability to understand sensory mechanisms under normal or injurious loading. Therefore, image-based, subject-specific, multiscale finite-element models were constructed to predict the mechanical responses of the human cervical facet capsular ligament under uniaxial tensile stretch. The models precisely simulated the force-displacement responses for all samples ([Formula: see text]) and showed promise in predicting the magnitude and location of peak regional strains at two different displacements. Yet, there was a loss of agreement between the model and experiment in terms of fiber organization at large tissue stretch, possibly due to a lack of accounting for tissue failure. The mean fiber stretch ratio predicted by the models was found to be significantly higher in regions that exhibited anomalous fiber realignment experimentally than in regions with normal realignment ([Formula: see text]). The development of microstructural abnormalities was associated with the predicted fiber-level stretch ([Formula: see text]), but not with the elemental maximum principal stress or maximum principal strain by logistic regression. The multiscale models elucidate a potential mechanical basis for predicting injury-prone tissue domains and for defining the relationships between macroscopic ligament stretch and microscale pathophysiology in the subfailure regime.
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Affiliation(s)
- Sijia Zhang
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Vahhab Zarei
- Department of Mechanical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, 55455, USA
| | - Beth A Winkelstein
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Victor H Barocas
- Department of Biomedical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, 55455, USA.
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Non-destructive two-photon excited fluorescence imaging identifies early nodules in calcific aortic-valve disease. Nat Biomed Eng 2017; 1:914-924. [PMID: 29456878 DOI: 10.1038/s41551-017-0152-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Calcifications occur during the development of healthy bone, and at the onset of calcific aortic-valve disease (CAVD) and many other pathologies. Although the mechanisms regulating early calcium deposition are not fully understood, they may provide targets for new treatments and for early interventions. Here, we show that two-photon excited fluorescence (TPEF) can provide quantitative and sensitive readouts of calcific nodule formation, in particular in the context of CAVD. Specifically, by means of the decomposition of TPEF spectral images from excised human CAVD valves and from rat bone prior to and following demineralization, as well as from calcific nodules formed within engineered gels, we identified an endogenous fluorophore that correlates with the level of mineralization in the samples. We then developed a ratiometric imaging approach that provides a quantitative readout of the presence of mineral deposits in early calcifications. TPEF should enable non-destructive, high-resolution imaging of three-dimensional tissue specimens for the assessment of the presence of calcification.
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20
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Halfwerk FR, Rouwkema J, Gossen JA, Grandjean JG. Supercritical carbon dioxide decellularised pericardium: Mechanical and structural characterisation for applications in cardio-thoracic surgery. J Mech Behav Biomed Mater 2017; 77:400-407. [PMID: 29020662 DOI: 10.1016/j.jmbbm.2017.10.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 09/11/2017] [Accepted: 10/01/2017] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Many biomaterials are used in cardio-thoracic surgery with good short-term results. However, calcification, dehiscence, and formation of scar tissue are reported. The aim of this research is to characterise decellularised pericardium after supercritical carbon dioxide (scCO2) processing as an alternative biological material for uses in cardio-thoracic surgery. METHODS Porcine and bovine pericardium were decellularised using scCO2. Mechanical properties such as tensile strength, elastic modulus, fracture toughness and suture retention strength were determined. Ultrastructure was visualised using Scanning Electron Microscopy. Water uptake and swelling was experimentally determined. Commercially available glutaraldehyde treated bovine pericardium was used as gold standard for comparison. RESULTS scCO2 decellularised porcine (and bovine pericardium) maintained their tensile strength compared to untreated native pericardium (13.3 ± 2.4MPa vs 14.0 ± 4.1MPa, p = 0.73). Tensile strength of glutaraldehyde treated pericardium was significantly higher compared to untreated pericardium (19.4 ± 7.3MPa vs 10.2 ± 2.2MPa, p = 0.02). Suture retention strength of scCO2 treated pericardium was significantly higher than glutaraldehyde treated pericardium (p = 0.01). We found no anisotropy of scCO2 or glutaraldehyde treated pericardium based on a trouser tear test. Ultrastructure was uncompromised in scCO2 treated pericardium, while glutaraldehyde treated pericardium showed deterioration of extracellular matrix. CONCLUSION scCO2 processing preserves initial mechanical and structural properties of porcine and bovine pericardium, while glutaraldehyde processing damages the extracellular matrix of bovine pericardium. Decellularisation of tissue using scCO2 might give long-term solutions for cardio-thoracic surgery without compromising initial good mechanical properties.
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Affiliation(s)
- Frank R Halfwerk
- Department of Cardio-Thoracic Surgery, Thoraxcentrum Twente, Medisch Spectrum Twente Hospital, PO Box 50000, 7500 KA Enschede, The Netherlands; Department of Biomechanical Engineering, Faculty of Engineering Technology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands.
| | - Jeroen Rouwkema
- Department of Biomechanical Engineering, Faculty of Engineering Technology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - Jan A Gossen
- European Medical Contract Manufacturing, 6545 CH Nijmegen, The Netherlands
| | - Jan G Grandjean
- Department of Cardio-Thoracic Surgery, Thoraxcentrum Twente, Medisch Spectrum Twente Hospital, PO Box 50000, 7500 KA Enschede, The Netherlands; Department of Biomechanical Engineering, Faculty of Engineering Technology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
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21
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Wu S, Duan B, Qin X, Butcher JT. Living nano-micro fibrous woven fabric/hydrogel composite scaffolds for heart valve engineering. Acta Biomater 2017; 51:89-100. [PMID: 28110071 DOI: 10.1016/j.actbio.2017.01.051] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 12/27/2016] [Accepted: 01/17/2017] [Indexed: 02/07/2023]
Abstract
Regeneration and repair of injured or diseased heart valves remains a clinical challenge. Tissue engineering provides a promising treatment approach to facilitate living heart valve repair and regeneration. Three-dimensional (3D) biomimetic scaffolds that possess heterogeneous and anisotropic features that approximate those of native heart valve tissue are beneficial to the successful in vitro development of tissue engineered heart valves (TEHV). Here we report the development and characterization of a novel composite scaffold consisting of nano- and micro-scale fibrous woven fabrics and 3D hydrogels by using textile techniques combined with bioactive hydrogel formation. Embedded nano-micro fibrous scaffolds within hydrogel enhanced mechanical strength and physical structural anisotropy of the composite scaffold (similar to native aortic valve leaflets) and also reduced its compaction. We determined that the composite scaffolds supported the growth of human aortic valve interstitial cells (HAVIC), balanced the remodeling of heart valve ECM against shrinkage, and maintained better physiological fibroblastic phenotype in both normal and diseased HAVIC over single materials. These fabricated composite scaffolds enable the engineering of a living heart valve graft with improved anisotropic structure and tissue biomechanics important for maintaining valve cell phenotypes. STATEMENT OF SIGNIFICANCE Heart valve-related disease is an important clinical problem, with over 300,000 surgical repairs performed annually. Tissue engineering offers a promising strategy for heart valve repair and regeneration. In this study, we developed and tissue engineered living nano-micro fibrous woven fabric/hydrogel composite scaffolds by using textile technique combined with bioactive hydrogel formation. The novelty of our technique is that the composite scaffolds can mimic physical structure anisotropy and the mechanical strength of natural aortic valve leaflet. Moreover, the composite scaffolds prevented the matrix shrinkage, which is major problem that causes the failure of TEHV, and better maintained physiological fibroblastic phenotype in both normal and diseased HAVIC. This work marks the first report of a combination composite scaffold using 3D hydrogel enhanced by nano-micro fibrous woven fabric, and represents a promising tissue engineering strategy to treat heart valve injury.
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22
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Labrosse MR, Jafar R, Ngu J, Boodhwani M. Planar biaxial testing of heart valve cusp replacement biomaterials: Experiments, theory and material constants. Acta Biomater 2016; 45:303-320. [PMID: 27570204 DOI: 10.1016/j.actbio.2016.08.036] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 07/22/2016] [Accepted: 08/19/2016] [Indexed: 12/13/2022]
Abstract
OBJECTIVES Aortic valve (AV) repair has become an attractive option to correct aortic insufficiency. Yet, cusp reconstruction with various cusp replacement materials has been associated with greater long-term repair failures, and it is still unknown how such materials mechanically compare with native leaflets. We used planar biaxial testing to characterize six clinically relevant cusp replacement materials, along with native porcine AV leaflets, to ascertain which materials would be best suited for valve repair. METHODS We tested at least six samples of: 1) fresh autologous porcine pericardium (APP), 2) glutaraldehyde fixed porcine pericardium (GPP), 3) St Jude Medical pericardial patch (SJM), 4) CardioCel patch (CC), 5) PeriGuard (PG), 6) Supple PeriGuard (SPG) and 7) fresh porcine AV leaflets (PC). We introduced efficient displacement-controlled testing protocols and processing, as well as advanced convexity requirements on the strain energy functions used to describe the mechanical response of the materials under loading. RESULTS The proposed experimental and data processing pipeline allowed for a robust in-plane characterization of all the materials tested, with constants determined for two Fung-like hyperelastic, anisotropic strain energy models. CONCLUSIONS Overall, CC and SPG (respectively PG) patches ranked as the closest mechanical equivalents to young (respectively aged) AV leaflets. Because the native leaflets as well as CC, PG and SPG patches exhibit significant anisotropic behaviors, it is suggested that the fiber and cross-fiber directions of these replacement biomaterials be matched with those of the host AV leaflets. STATEMENT OF SIGNIFICANCE The long-term performance of cusp replacement materials would ideally be evaluated in large animal models for AV disease and cusp repair, and over several months or more. Given the unavailability and impracticality of such models, detailed information on stress-strain behavior, as studied herein, and investigations of durability and valve dynamics will be the best surrogates, as they have been for prosthetic valves. Overall, comparison with Fig. 3 suggests that CC and SPG (respectively PG) patches may be the closest mechanical equivalents to young (respectively aged) AV leaflets. Interestingly, the thicknesses of these materials are close to those reported for porcine and younger human AV leaflets, which may facilitate surgical implantation, by contrast to the thinner APP which has poor handling qualities. Because the native leaflets as well as CC, PG and SPG patches exhibit anisotropic behaviors, from a mechanistic perspective alone, it stands to reason that cardiac surgeons should seek to intraoperatively match the fiber and cross-fiber directions of these replacement biomaterials with those of the repaired AV leaflets.
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Affiliation(s)
- Michel R Labrosse
- Department of Mechanical Engineering, University of Ottawa, 161 Louis Pasteur, Ottawa, Ontario K1N 6N5, Canada; Division of Cardiac Surgery, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, Ontario K1Y 4W7, Canada.
| | - Reza Jafar
- Department of Mechanical Engineering, University of Ottawa, 161 Louis Pasteur, Ottawa, Ontario K1N 6N5, Canada; Division of Cardiac Surgery, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, Ontario K1Y 4W7, Canada
| | - Janet Ngu
- Division of Cardiac Surgery, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, Ontario K1Y 4W7, Canada
| | - Munir Boodhwani
- Division of Cardiac Surgery, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, Ontario K1Y 4W7, Canada
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Kheradvar A, Groves EM, Falahatpisheh A, Mofrad MK, Hamed Alavi S, Tranquillo R, Dasi LP, Simmons CA, Jane Grande-Allen K, Goergen CJ, Baaijens F, Little SH, Canic S, Griffith B. Emerging Trends in Heart Valve Engineering: Part IV. Computational Modeling and Experimental Studies. Ann Biomed Eng 2015. [PMID: 26224522 DOI: 10.1007/s10439-015-1394-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
In this final portion of an extensive review of heart valve engineering, we focus on the computational methods and experimental studies related to heart valves. The discussion begins with a thorough review of computational modeling and the governing equations of fluid and structural interaction. We then move onto multiscale and disease specific modeling. Finally, advanced methods related to in vitro testing of the heart valves are reviewed. This section of the review series is intended to illustrate application of computational methods and experimental studies and their interrelation for studying heart valves.
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Affiliation(s)
- Arash Kheradvar
- Department of Biomedical Engineering, The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, 2410 Engineering Hall, Irvine, CA, 92697-2730, USA. .,Department of Medicine, Division of Cardiology, University of California, Irvine School of Medicine, Irvine, CA, USA.
| | - Elliott M Groves
- Department of Biomedical Engineering, The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, 2410 Engineering Hall, Irvine, CA, 92697-2730, USA.,Department of Medicine, Division of Cardiology, University of California, Irvine School of Medicine, Irvine, CA, USA
| | - Ahmad Falahatpisheh
- Department of Biomedical Engineering, The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, 2410 Engineering Hall, Irvine, CA, 92697-2730, USA
| | - Mohammad K Mofrad
- Department of Bioengineering and Mechanical Engineering, University of California, Berkeley, CA, USA
| | - S Hamed Alavi
- Department of Biomedical Engineering, The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, 2410 Engineering Hall, Irvine, CA, 92697-2730, USA
| | - Robert Tranquillo
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Lakshmi P Dasi
- Department of Mechanical Engineering, School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Craig A Simmons
- Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, ON, Canada.,Institute of Biomaterials & Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | | | - Craig J Goergen
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Frank Baaijens
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Stephen H Little
- Houston Methodist DeBakey Heart & Vascular Center, Houston, TX, USA
| | - Suncica Canic
- Department of Mathematics, University of Houston, Houston, TX, USA
| | - Boyce Griffith
- Department of Mathematics, Center for Interdisciplinary Applied Mathematics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,McAllister Heart Institute, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
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Alavi SH, Sinha A, Steward E, Milliken JC, Kheradvar A. Load-dependent extracellular matrix organization in atrioventricular heart valves: differences and similarities. Am J Physiol Heart Circ Physiol 2015; 309:H276-84. [DOI: 10.1152/ajpheart.00164.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 05/17/2015] [Indexed: 12/31/2022]
Abstract
The extracellular matrix of the atrioventricular (AV) valves' leaflets has a key role in the ability of these valves to properly remodel in response to constantly varying physiological loads. While the loading on mitral and tricuspid valves is significantly different, no information is available on how collagen fibers change their orientation in response to these loads. This study delineates the effect of physiological loading on AV valves' leaflets microstructures using Second Harmonic Generation (SHG) microscopy. Fresh natural porcine tricuspid and mitral valves' leaflets ( n = 12/valve type) were cut and prepared for the experiments. Histology and immunohistochemistry were performed to compare the microstructural differences between the valves. The specimens were imaged live during the relaxed, loading, and unloading phases using SHG microscopy. The images were analyzed with Fourier decomposition to mathematically seek changes in collagen fiber orientation. Despite the similarities in both AV valves as seen in the histology and immunohistochemistry data, the microstructural arrangement, especially the collagen fiber distribution and orientation in the stress-free condition, were found to be different. Uniaxial loading was dependent on the arrangement of the fibers in their relaxed mode, which led the fibers to reorient in-line with the load throughout the depth of the mitral leaflet but only to reorient in-line with the load in deeper layers of the tricuspid leaflet. Biaxial loading arranged the fibers in between the two principal axes of the stresses independently from their relaxed states. Unlike previous findings, this study concludes that the AV valves' three-dimensional extracellular fiber arrangement is significantly different in their stress-free and uniaxially loaded states; however, fiber rearrangement in response to the biaxial loading remains similar.
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Affiliation(s)
- S. Hamed Alavi
- The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, Irvine, California
- Department Biomedical Engineering, University of California, Irvine, Irvine, California; and
| | - Aditi Sinha
- The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, Irvine, California
- Department Biomedical Engineering, University of California, Irvine, Irvine, California; and
| | - Earl Steward
- Division of Cardiothoracic Surgery, University of California, Irvine, Irvine, California
| | - Jeffrey C. Milliken
- Division of Cardiothoracic Surgery, University of California, Irvine, Irvine, California
| | - Arash Kheradvar
- The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, Irvine, California
- Department Biomedical Engineering, University of California, Irvine, Irvine, California; and
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Collagen Fibrils in Skin Orient in the Direction of Applied Uniaxial Load in Proportion to Stress while Exhibiting Differential Strains around Hair Follicles. MATERIALS 2015; 8:1841-1857. [PMID: 28788035 PMCID: PMC5507025 DOI: 10.3390/ma8041841] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 04/09/2015] [Accepted: 04/14/2015] [Indexed: 11/17/2022]
Abstract
We determined inhomogeneity of strains around discontinuities as well as changes in orientation of collagen fibrils under applied load in skin. Second Harmonic Generation (SHG) images of collagen fibrils were obtained at different strain magnitudes. Changes in collagen orientation were analyzed using Fast Fourier Transforms (FFT) while strain inhomogeneity was determined at different distances from hair follicles using Digital Image Correlation (DIC). A parameter, defined as the Collagen Orientation Index (COI), is introduced that accounts for the increasingly ellipsoidal nature of the FFT amplitude images upon loading. We show that the COI demonstrates two distinct mechanical regimes, one at low strains (0%, 2.5%, 5% strain) in which randomly oriented collagen fibrils align in the direction of applied deformation. In the second regime, beginning at 5% strain, collagen fibrils elongate in response to applied deformation. Furthermore, the COI is also found to be linearly correlated with the applied stress indicating that collagen fibrils orient to take the applied load. DIC results indicated that major principal strains were found to increase with increased load at all locations. In contrast, minimum principal strain was dependent on distance from hair follicles. These findings are significant because global and local changes in collagen deformations are expected to be changed by disease, and could affect stem cell populations surrounding hair follicles, including mesenchymal stem cells within the outer root sheath.
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Wu PC, Hsieh TY, Tsai ZU, Liu TM. In vivo quantification of the structural changes of collagens in a melanoma microenvironment with second and third harmonic generation microscopy. Sci Rep 2015; 5:8879. [PMID: 25748390 PMCID: PMC4352861 DOI: 10.1038/srep08879] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 02/02/2015] [Indexed: 01/13/2023] Open
Abstract
Using in vivo second harmonic generation (SHG) and third harmonic generation (THG) microscopies, we tracked the course of collagen remodeling over time in the same melanoma microenvironment within an individual mouse. The corresponding structural and morphological changes were quantitatively analyzed without labeling using an orientation index (OI), the gray level co-occurrence matrix (GLCM) method, and the intensity ratio of THG to SHG (RTHG/SHG). In the early stage of melanoma development, we found that collagen fibers adjacent to a melanoma have increased OI values and SHG intensities. In the late stages, these collagen networks have more directionality and less homogeneity. The corresponding GLCM traces showed oscillation features and the sum of squared fluctuation VarGLCM increased with the tumor sizes. In addition, the THG intensities of the extracellular matrices increased, indicating an enhanced optical inhomogeneity. Multiplying OI, VarGLCM, and RTHG/SHG together, the combinational collagen remodeling (CR) index at 4 weeks post melanoma implantation showed a 400-times higher value than normal ones. These results validate that our quantitative indices of SHG and THG microscopies are sensitive enough to diagnose the collagen remodeling in vivo. We believe these indices have the potential to help the diagnosis of skin cancers in clinical practice.
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Affiliation(s)
- Pei-Chun Wu
- Institute of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Tsung-Yuan Hsieh
- Institute of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Zen-Uong Tsai
- Molecular Imaging Center, National Taiwan University, Taipei 10617, Taiwan
| | - Tzu-Ming Liu
- Institute of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan
- Molecular Imaging Center, National Taiwan University, Taipei 10617, Taiwan
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Cortes DH, Elliott DM. Accurate Prediction of Stress in Fibers with Distributed Orientations Using Generalized High-Order Structure Tensors. MECHANICS OF MATERIALS : AN INTERNATIONAL JOURNAL 2014; 75:73-83. [PMID: 24926114 PMCID: PMC4048881 DOI: 10.1016/j.mechmat.2014.04.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The orientation of collagen fibers plays an important role on the mechanics of connective tissues. Connective tissues have fibers with different orientation distributions. The angular integration formulation used to model the mechanics of fibers with distributed orientation is accurate, but computationally expensive for numerical methods such as finite elements. This study presents a formulation based on pre-integrated Generalized High-Order Structure Tensors (GHOST) which greatly improves the accuracy of the predicted stress. Simplifications of the GHOST formulation for transversely-isotropic and planar fiber distributions are also presented. Additionally, the GHOST and the angular integration formulations are compared for different loading conditions, fiber orientation functions, strain energy functions and degrees of fiber non-linearity. It was found that the GHOST formulation predicted the stress of the fibers with an error lower than 10% for uniaxial and biaxial tension. Fiber non-linearity increased the error of the GHOST formulation; however, the error was reduced to negligible values by considering higher order structure tensors. The GHOST formulation produced lower errors when used with an elliptical fiber density function and a binomial strain energy function. In conclusion, the GHOST formulation is able to accurately predict the stress of fibers with distributed orientation without requiring numerous integral calculations. Consequently, the GHOST formulation may reduce the computational effort needed to analyze the mechanics of fibrous tissues with distributed orientations.
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Affiliation(s)
- Daniel H. Cortes
- Corresponding Author: Daniel H. Cortes, Ph.D., University of Delaware, Department of Biomedical Engineering, 125 E Delaware Ave., Newark, DE 19716,
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Masoumi N, Annabi N, Assmann A, Larson BL, Hjortnaes J, Alemdar N, Kharaziha M, Manning KB, Mayer JE, Khademhosseini A. Tri-layered elastomeric scaffolds for engineering heart valve leaflets. Biomaterials 2014; 35:7774-85. [PMID: 24947233 DOI: 10.1016/j.biomaterials.2014.04.039] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 04/14/2014] [Indexed: 12/12/2022]
Abstract
Tissue engineered heart valves (TEHVs) that can grow and remodel have the potential to serve as permanent replacements of the current non-viable prosthetic valves particularly for pediatric patients. A major challenge in designing functional TEHVs is to mimic both structural and anisotropic mechanical characteristics of the native valve leaflets. To establish a more biomimetic model of TEHV, we fabricated tri-layered scaffolds by combining electrospinning and microfabrication techniques. These constructs were fabricated by assembling microfabricated poly(glycerol sebacate) (PGS) and fibrous PGS/poly(caprolactone) (PCL) electrospun sheets to develop elastic scaffolds with tunable anisotropic mechanical properties similar to the mechanical characteristics of the native heart valves. The engineered scaffolds supported the growth of valvular interstitial cells (VICs) and mesenchymal stem cells (MSCs) within the 3D structure and promoted the deposition of heart valve extracellular matrix (ECM). MSCs were also organized and aligned along the anisotropic axes of the engineered tri-layered scaffolds. In addition, the fabricated constructs opened and closed properly in an ex vivo model of porcine heart valve leaflet tissue replacement. The engineered tri-layered scaffolds have the potential for successful translation towards TEHV replacements.
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Affiliation(s)
- Nafiseh Masoumi
- Biomaterials Innovation Research Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA; Department of Cardiac Surgery, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Bioengineering, The Pennsylvania State University, 205 Hallowell Building, State College, PA 16802, USA; Harvard-MIT Division of Health Sciences and Technology and The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 500 Main Street, Cambridge, MA 02139, USA
| | - Nasim Annabi
- Biomaterials Innovation Research Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, Boston, MA 02115, USA
| | - Alexander Assmann
- Biomaterials Innovation Research Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, Boston, MA 02115, USA; Department of Cardiovascular Surgery and Research Group for Experimental Surgery, Heinrich Heine University, Medical Faculty, Moorenstr. 5, Dusseldorf 40225, Germany
| | - Benjamin L Larson
- Harvard-MIT Division of Health Sciences and Technology and The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 500 Main Street, Cambridge, MA 02139, USA
| | - Jesper Hjortnaes
- Biomaterials Innovation Research Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA; Department of Cardiothoracic Surgery, University Medical Center Utrecht, Heidelberglaan 100, Utrecht, Netherlands
| | - Neslihan Alemdar
- Biomaterials Innovation Research Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA
| | - Mahshid Kharaziha
- Biomaterials Innovation Research Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA
| | - Keefe B Manning
- Department of Bioengineering, The Pennsylvania State University, 205 Hallowell Building, State College, PA 16802, USA
| | - John E Mayer
- Department of Cardiac Surgery, Boston Children's Hospital and Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
| | - Ali Khademhosseini
- Biomaterials Innovation Research Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, 65 Landsdowne Street, Cambridge, MA 02139, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, Boston, MA 02115, USA; Department of Physics, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21569, Saudi Arabia.
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Masoumi N, Larson BL, Annabi N, Kharaziha M, Zamanian B, Shapero KS, Cubberley AT, Camci-Unal G, Manning KB, Mayer JE, Khademhosseini A. Electrospun PGS:PCL microfibers align human valvular interstitial cells and provide tunable scaffold anisotropy. Adv Healthc Mater 2014; 3:929-39. [PMID: 24453182 PMCID: PMC4053480 DOI: 10.1002/adhm.201300505] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 10/09/2013] [Indexed: 12/23/2022]
Abstract
Tissue engineered heart valves (TEHV) can be useful in the repair of congenital or acquired valvular diseases due to their potential for growth and remodeling. The development of biomimetic scaffolds is a major challenge in heart valve tissue engineering. One of the most important structural characteristics of mature heart valve leaflets is their intrinsic anisotropy, which is derived from the microstructure of aligned collagen fibers in the extracellular matrix (ECM). In the present study, a directional electrospinning technique is used to fabricate fibrous poly(glycerol sebacate):poly(caprolactone) (PGS:PCL) scaffolds containing aligned fibers, which resemble native heart valve leaflet ECM networks. In addition, the anisotropic mechanical characteristics of fabricated scaffolds are tuned by changing the ratio of PGS:PCL to mimic the native heart valve's mechanical properties. Primary human valvular interstitial cells (VICs) attach and align along the anisotropic axes of all PGS:PCL scaffolds with various mechanical properties. The cells are also biochemically active in producing heart-valve-associated collagen, vimentin, and smooth muscle actin as determined by gene expression. The fibrous PGS:PCL scaffolds seeded with human VICs mimick the structure and mechanical properties of native valve leaflet tissues and would potentially be suitable for the replacement of heart valves in diverse patient populations.
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Affiliation(s)
- Nafiseh Masoumi
- Department of Bioengineering, The Pennsylvania State University, 205 Hallowell Building, Sate College, PA, USA. Center for Biomedical Engineering, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology Massachusetts Institute of Technology, 65 Landsdowne St., Cambridge, 02139 MA, USA. Department of Cardiac Surgery, Boston Children Hospital and Harvard Medical School 300 Longwood Ave, Boston, MA 02115, USA
| | - Benjamin L. Larson
- Harvard-MIT Division of Health Sciences and Technology and the David Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 500 Main Street, Cambridge, MA 02139, USA
| | - Nasim Annabi
- Center for Biomedical Engineering, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology Massachusetts Institute of Technology, 65 Landsdowne St., Cambridge, 02139 MA, USA. Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Cir, Boston, MA 02115, USA
| | - Mahshid Kharaziha
- Center for Biomedical Engineering, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology Massachusetts Institute of Technology, 65 Landsdowne St., Cambridge, 02139 MA, USA
| | - Behnam Zamanian
- Center for Biomedical Engineering, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology Massachusetts Institute of Technology, 65 Landsdowne St., Cambridge, 02139 MA, USA
| | - Kayle S. Shapero
- Department of Cardiac Surgery, Boston Children Hospital and Harvard Medical School, 300 Longwood Ave, Boston, MA 02115, USA
| | - Alexander T. Cubberley
- Department of Cardiac Surgery, Boston Children Hospital and Harvard Medical School, 300 Longwood Ave, Boston, MA 02115, USA
| | - Gulden Camci-Unal
- Department of Bioengineering, The Pennsylvania State University, 205 Hallowell Building, Sate College, PA, USA
| | - Keefe. B. Manning
- Department of Bioengineering, The Pennsylvania State University, 205 Hallowell Building, Sate College, PA, USA
| | - John E. Mayer
- Department of Cardiac Surgery, Boston Children Hospital and Harvard Medical School, 300 Longwood Ave, Boston, MA 02115, USA
| | - Ali Khademhosseini
- Center for Biomedical Engineering, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Harvard-MIT Division of Health Sciences and Technology Massachusetts Institute of Technology, 65 Landsdowne St., Cambridge, 02139 MA, USA. Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Cir, Boston, MA 02115, USA
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The Effects of Transcatheter Valve Crimping on Pericardial Leaflets. Ann Thorac Surg 2014; 97:1260-6. [DOI: 10.1016/j.athoracsur.2013.11.009] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Revised: 10/07/2013] [Accepted: 11/08/2013] [Indexed: 11/19/2022]
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Robertson C, Ikemura K, Krasieva TB, George SC. Multiscale analysis of collagen microstructure with generalized image correlation spectroscopy and the detection of tissue prestress. Biomaterials 2013; 34:6127-32. [PMID: 23642533 DOI: 10.1016/j.biomaterials.2013.04.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Accepted: 04/10/2013] [Indexed: 12/13/2022]
Abstract
Prestress in tissue is currently detected through destructive methods which obviate both in vivo and longitudinal assessment. We hypothesized that prestress could be detected and quantified by analyzing the microstructure of the extracellular matrix at different spatial scales using non-invasive and non-destructive optical imaging. A simple model of tissue prestress was created using fibroblast-mediated contraction of collagen gels around a central mandrel. Using a quantitative, multiscale, image processing technique, termed generalized image correlation spectroscopy (GICS) of second harmonic images, collagen fiber number and alignment at three different length scales characteristic of the collagen fibril, collagen fiber, and cell were analyzed. GICS fiber alignment (σ(maj/min)) was significantly different across load state, level of prestress, and length scale. The largest fiber ratio, and thus highest alignment, was seen in prestressed, externally loaded gels at a length scale equivalent to the size of the fibroblast cells. Alignment at both fiber and cell scale correlated with prestress in this model. We conclude that GICS of second harmonic images of collagen can predict prestress, and that microstructural organization at the collagen fiber and cell scale are the primary determinants of prestress in cellularized collagen gels.
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Affiliation(s)
- Claire Robertson
- Department of Biomedical Engineering, University of California, Irvine, CA, USA
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