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Valente R, Mourato A, Xavier J, Sousa P, Domingues T, Tavares P, Avril S, Tomás A, Fragata J. Experimental Protocols to Test Aortic Soft Tissues: A Systematic Review. Bioengineering (Basel) 2024; 11:745. [PMID: 39199703 PMCID: PMC11351783 DOI: 10.3390/bioengineering11080745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2024] [Accepted: 07/18/2024] [Indexed: 09/01/2024] Open
Abstract
Experimental protocols are fundamental for quantifying the mechanical behaviour of soft tissue. These data are crucial for advancing the understanding of soft tissue mechanics, developing and calibrating constitutive models, and informing the development of more accurate and predictive computational simulations and artificial intelligence tools. This paper offers a comprehensive review of experimental tests conducted on soft aortic tissues, employing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology, based on the Scopus, Web of Science, IEEE, Google Scholar and PubMed databases. This study includes a detailed overview of the test method protocols, providing insights into practical methodologies, specimen preparation and full-field measurements. The review also briefly discusses the post-processing methods applied to extract material parameters from experimental data. In particular, the results are analysed and discussed providing representative domains of stress-strain curves for both uniaxial and biaxial tests on human aortic tissue.
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Affiliation(s)
- Rodrigo Valente
- UNIDEMI, Department of Mechanical and Industrial Engineering, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal; (R.V.); (A.M.)
| | - André Mourato
- UNIDEMI, Department of Mechanical and Industrial Engineering, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal; (R.V.); (A.M.)
| | - José Xavier
- UNIDEMI, Department of Mechanical and Industrial Engineering, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal; (R.V.); (A.M.)
- Intelligent Systems Associate Laboratory, LASI, 4800-058 Guimarães, Portugal
| | - Pedro Sousa
- INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal; (P.S.); (P.T.)
| | - Tiago Domingues
- INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal; (P.S.); (P.T.)
| | - Paulo Tavares
- INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal; (P.S.); (P.T.)
| | - Stéphane Avril
- Mines Saint-Etienne, University of Lyon, Inserm, Sainbiose U1059, Campus Santé Innovation, 10, rue de la Marandière, 42270 Saint-Priest-en-Jarez, France;
| | - António Tomás
- Department of Cardiothoracic Surgery, Santa Marta Hospital, Rua de Santa Marta, 1169-024 Lisboa, Portugal; (A.T.); (J.F.)
| | - José Fragata
- Department of Cardiothoracic Surgery, Santa Marta Hospital, Rua de Santa Marta, 1169-024 Lisboa, Portugal; (A.T.); (J.F.)
- Department of Surgery and Human Morphology, NOVA Medical School, Universidade NOVA de Lisboa, Campo Mártires da Pátria, 1169-056 Lisboa, Portugal
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Gkousioudi A, Razzoli M, Moreira JD, Wainford RD, Zhang Y. Renal denervation restores biomechanics of carotid arteries in a rat model of hypertension. Sci Rep 2024; 14:495. [PMID: 38177257 PMCID: PMC10767006 DOI: 10.1038/s41598-023-50816-8] [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: 08/17/2023] [Accepted: 12/26/2023] [Indexed: 01/06/2024] Open
Abstract
The prevalence of hypertension increases with aging and is associated with increased arterial stiffness. Resistant hypertension is presented when drug treatments fail to regulate a sustained increased blood pressure. Given that the mechanisms between the sympathetic nervous system and the kidney play an important role in blood regulation, renal denervation (RDN) has emerged as a therapeutic potential in resistant hypertension. In this study, we investigated the effects of RDN on the biomechanical response and microstructure of elastic arteries. Common carotid arteries (CCA) excised from 3-month, 8-month, and 8-month denervated rats were subjected to biaxial extension-inflation test. Our results showed that hypertension developed in the 8-month-old rats. The sustained elevated blood pressure resulted in arterial remodeling which was manifested as a significant stress increase in both axial and circumferential directions after 8 months. RDN had a favorable impact on CCAs with a restoration of stresses in values similar to control arteries at 3 months. After biomechanical testing, arteries were imaged under a multi-photon microscope to identify microstructural changes in extracellular matrix (ECM). Quantification of multi-photon images showed no significant alterations of the main ECM components, elastic and collagen fibers, indicating that arteries remained intact after RDN. Regardless of the experimental group, our microstructural analysis of the multi-photon images revealed that reorientation of the collagen fibers might be the main microstructural mechanism taking place during pressurization with their straightening happening during axial stretching.
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Affiliation(s)
- Anastasia Gkousioudi
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Margherita Razzoli
- Department of Biomedical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Jesse D Moreira
- Department of Pharmacology & Experimental Therapeutics, School of Medicine, Boston University Avedisian and Chobanian, Boston, MA, USA
| | - Richard D Wainford
- Department of Pharmacology & Experimental Therapeutics, School of Medicine, Boston University Avedisian and Chobanian, Boston, MA, USA.
- Division of Cardiology, School of Medicine, HSRB II, Emory University, 1750 Haygood Drive, Atlanta, GA, 30322, USA.
| | - Yanhang Zhang
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA.
- Department of Biomedical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA.
- Division of Materials Science & Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA.
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3
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Gkousioudi A, Sigaeva T, Yu X, Seta F, Wainford RD, Zhang Y. Compromised homeostasis in aged carotid arteries revealed by microstructural studies of elastic lamellae. J Mech Behav Biomed Mater 2023; 148:106187. [PMID: 37875040 PMCID: PMC10877240 DOI: 10.1016/j.jmbbm.2023.106187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/07/2023] [Accepted: 10/10/2023] [Indexed: 10/26/2023]
Abstract
Healthy arteries are continuously subjected to diverse mechanical stimuli and adapt in order to maintain a mechanical homeostasis which is characterized by a uniform distribution of wall stresses. However, aging may compromise the homeostatic microenvironment within arteries. Structural heterogeneity has been suggested as a potential microstructural mechanism that could lead to homogeneous stress distribution across the arterial wall. Our previous study on the unfolding and stretching of the elastic lamellae revealed the underlying microstructural mechanism for equalizing the circumferential stresses through wall; inner elastic layers are wavier and unfold more than the outer layers which helps to evenly distribute lamellar stretching (Yu et al., 2018). In this study, we investigated the effect of aging on lamellar deformation and its implications for tissue homeostasis. Common carotid arteries from aged mice were imaged under a multi-photon microscope while subjected to biaxial extension and inflation at five different pressures ranging from 0 up to 120 mmHg. Lamellar unfolding during pressurization was then determined from the reconstructed cross-sectional images of elastic lamellae. Tissue-level circumferential stretch was combined with the lamellar unfolding to calculate lamellar stretching. Our results revealed that the straightness gradient of aged elastic lamellae is similar to the young ones. However, during pressurization, the inner elastic lamella of the aged mice unfolded significantly more than the inner layer in young arteries. An important finding of our study is the uneven increase in inter-lamellar space which contributed to a nonuniform stretching of the elastic lamellae of aged mice arteries, elevated stress gradient, and a shifting of the load-bearing component to adventitia. Our results shed light into the complex microstructural mechanisms that take place in aging and adversely affect arterial mechanical behavior and homeostasis.
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Affiliation(s)
- Anastasia Gkousioudi
- Department of Mechanical Engineering, Boston University, Boston, MA, United States
| | - Taisiya Sigaeva
- Department of Systems Design Engineering, University of Waterloo, Waterloo, Ontario, Canada; Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, Alberta, Canada
| | - Xunjie Yu
- Department of Mechanical Engineering, Boston University, Boston, MA, United States
| | - Francesca Seta
- Department of Medicine, Vascular Biology Section, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, United States
| | - Richard D Wainford
- Department of Pharmacology & Experimental Therapeutics, Boston University Avedisian and Chobanian School of Medicine, Boston, MA, United States; Division of Cardiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Yanhang Zhang
- Department of Mechanical Engineering, Boston University, Boston, MA, United States; Department of Biomedical Engineering, Boston University, Boston, MA, United States; Division of Materials Science and Engineering, Boston University, Boston, MA, United States.
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4
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Liu X, Halvorsen S, Blanke N, Downs M, Stein TD, Bigio IJ, Zaia J, Zhang Y. Progressive mechanical and structural changes in anterior cerebral arteries with Alzheimer's disease. Alzheimers Res Ther 2023; 15:185. [PMID: 37891618 PMCID: PMC10605786 DOI: 10.1186/s13195-023-01331-5] [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: 08/21/2023] [Accepted: 10/10/2023] [Indexed: 10/29/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease and the main cause for dementia. The irreversible neurodegeneration leads to a gradual loss of brain function characterized predominantly by memory loss. Cerebrovascular changes are common neuropathologic findings in aged subjects with dementia. Cerebrovascular integrity is critical for proper metabolism and perfusion of the brain, as cerebrovascular remodeling may render the brain more susceptible to pulse pressure and may be associated with poorer cognitive performance and greater risk of cerebrovascular events. The objective of this study is to provide understanding of cerebrovascular remodeling with AD progression. Anterior cerebral arteries (ACAs) from a total of 19 brain donor participants from controls and pathologically diagnosed AD groups (early-Braak stages I-II; intermediate-Braak stages III-IV; and advanced-Braak stages V-VI) were included in this study. Mechanical testing, histology, advanced optical imaging, and mass spectrometry were performed to study the progressive structural and functional changes of ACAs with AD progression. Biaxial extension-inflation tests showed that ACAs became progressively less compliant, and the longitudinal stress in the intermediate and advanced AD groups was significantly higher than that from the control group. With pathological AD development, the inner and outer diameters of the ACAs remained almost unchanged; however, histology study revealed progressive smooth muscle cell atrophy and loss of elastic fibers which led to compromised structural integrity of the arterial wall. Multiphoton imaging demonstrated elastin degradation at the media-adventitia interface, which led to the formation of an empty band of 21.0 ± 15.4 μm and 32.8 ± 9.24 μm in width for the intermediate and advanced AD groups, respectively. Furthermore, quantitative birefringence microscopy showed disorganized adventitial collagen with AD development. Mass spectrometry analysis provided further evidence of altered collagen content and other extracellular matrix (ECM) molecule and smooth muscle cell changes that were consistent with the mechanical and structural alterations. Collectively, our study provides understanding of the mechanical and structural cerebrovascular deterioration in cerebral arteries with AD, which may be related to neurodegenration and pathology in the brain.
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Affiliation(s)
- Xiaozhu Liu
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Samuel Halvorsen
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Nathan Blanke
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Margaret Downs
- Department of Biochemistry and Cell Biology, Boston University, Avedisian School of Medicine, Chobanian &, Boston, MA, USA
| | - Thor D Stein
- Pathology and Laboratory Medicine, Boston University, Boston, MA, USA
- VA Boston Healthcare System, U.S. Department of Veteran Affairs, Jamaica Plain, MA, USA
- VA Bedford Healthcare System, U.S. Department of Veteran Affairs, Bedford, MA, USA
| | - Irving J Bigio
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Joseph Zaia
- Department of Biochemistry and Cell Biology, Boston University, Avedisian School of Medicine, Chobanian &, Boston, MA, USA
| | - Yanhang Zhang
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA.
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA.
- Division of Materials Science & Engineering, Boston University, Boston, MA, 02215, USA.
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5
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Halvorsen S, Wang R, Zhang Y. Contribution of Elastic and Collagen Fibers to the Mechanical Behavior of Bovine Nuchal Ligament. Ann Biomed Eng 2023; 51:2204-2215. [PMID: 37284997 PMCID: PMC10528717 DOI: 10.1007/s10439-023-03254-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 05/16/2023] [Indexed: 06/08/2023]
Abstract
Ligamentum nuchae is a highly elastic tissue commonly used to study the structure and mechanics of elastin. This study combines imaging, mechanical testing, and constitutive modeling to examine the structural organization of elastic and collagen fibers and their contributions to the nonlinear stress-strain behavior of the tissue. Rectangular samples of bovine ligamentum nuchae cut in both longitudinal and transverse directions were tested in uniaxial tension. Purified elastin samples were also obtained and tested. It was observed that the stress-stretch response of purified elastin tissue follows a similar curve as the intact tissue initially, but the intact tissue shows a significant stiffening behavior for stretches above 1.29 with collagen engagement. Multiphoton and histology images confirm the elastin-dominated bulk of ligamentum nuchae interspersed with small bundles of collagen fibrils and sporadic collagen-rich regions with cellular components and ground substance. A transversely isotropic constitutive model that considers the longitudinal organization of elastic and collagen fibers was developed to describe the mechanical behavior of both intact and purified elastin tissue under uniaxial tension. These findings shed light on the unique structural and mechanical roles of elastic and collagen fibers in tissue mechanics and may aid in future use of ligamentum nuchae in tissue grafting.
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Affiliation(s)
- Samuel Halvorsen
- Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Ruizhi Wang
- Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Yanhang Zhang
- Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA.
- Biomedical Engineering, Boston University, Boston, MA, USA.
- Division of Materials Science & Engineering, Boston University, Boston, MA, USA.
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6
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Gkousioudi A, Razzoli M, Moreira JD, Wainford RD, Zhang Y. Renal denervation restores biomechanics of carotid arteries in a rat model of hypertension. RESEARCH SQUARE 2023:rs.3.rs-3273236. [PMID: 37720022 PMCID: PMC10503847 DOI: 10.21203/rs.3.rs-3273236/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
The prevalence of hypertension increases with aging and is associated with increased arterial stiffness. Resistant hypertension is presented when drug treatments fail to regulate a sustained increased blood pressure. Given that the mechanisms between the sympathetic nervous system and the kidney play an important role in blood regulation, renal denervation (RDN) has emerged as a therapeutic potential in resistant hypertension. In this study, we investigated the effects of RDN on the biomechanical response and microstructure of elastic arteries. Common carotid arteries (CCA) were excised from 3-, 8- and 8-month-old denervated rats, and subjected to biaxial extension-inflation test. Our results showed that hypertension developed in the 8-month-old rats. The sustained elevated blood pressure resulted in arterial remodeling which was manifested as a significant stress increase in both axial and circumferential directions after 8 months. RDN had a favorable impact on CCAs with a restoration of stresses in values similar to control arteries at 3 months. After biomechanical testing, arteries were imaged under a multi-photon microscope to identify microstructural changes in extracellular matrix (ECM). Quantification of multi-photon images showed no significant alterations of the main ECM components, elastic and collagen fibers, indicating that arteries remained intact after RDN. Regardless of the experimental group, our microstructural analysis of the multi-photon images revealed that reorientation of the collagen fibers might be the main microstructural mechanism taking place during pressurization with their straightening happening during axial stretching.
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Affiliation(s)
| | | | - Jesse D Moreira
- Boston University Avedisian and Chobanian School of Medicine
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7
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Pele KG, Amaveda H, Mora M, Marcuello C, Lostao A, Alamán-Díez P, Pérez-Huertas S, Ángeles Pérez M, García-Aznar JM, García-Gareta E. Hydrocolloids of Egg White and Gelatin as a Platform for Hydrogel-Based Tissue Engineering. Gels 2023; 9:505. [PMID: 37367175 DOI: 10.3390/gels9060505] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 06/05/2023] [Accepted: 06/15/2023] [Indexed: 06/28/2023] Open
Abstract
Innovative materials are needed to produce scaffolds for various tissue engineering and regenerative medicine (TERM) applications, including tissue models. Materials derived from natural sources that offer low production costs, easy availability, and high bioactivity are highly preferred. Chicken egg white (EW) is an overlooked protein-based material. Whilst its combination with the biopolymer gelatin has been investigated in the food technology industry, mixed hydrocolloids of EW and gelatin have not been reported in TERM. This paper investigates these hydrocolloids as a suitable platform for hydrogel-based tissue engineering, including 2D coating films, miniaturized 3D hydrogels in microfluidic devices, and 3D hydrogel scaffolds. Rheological assessment of the hydrocolloid solutions suggested that temperature and EW concentration can be used to fine-tune the viscosity of the ensuing gels. Fabricated thin 2D hydrocolloid films presented globular nano-topography and in vitro cell work showed that the mixed hydrocolloids had increased cell growth compared with EW films. Results showed that hydrocolloids of EW and gelatin can be used for creating a 3D hydrogel environment for cell studies inside microfluidic devices. Finally, 3D hydrogel scaffolds were fabricated by sequential temperature-dependent gelation followed by chemical cross-linking of the polymeric network of the hydrogel for added mechanical strength and stability. These 3D hydrogel scaffolds displayed pores, lamellae, globular nano-topography, tunable mechanical properties, high affinity for water, and cell proliferation and penetration properties. In conclusion, the large range of properties and characteristics of these materials provide a strong potential for a large variety of TERM applications, including cancer models, organoid growth, compatibility with bioprinting, or implantable devices.
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Affiliation(s)
- Karinna Georgiana Pele
- Multiscale in Mechanical & Biological Engineering Research Group, Aragon Institute of Engineering Research (I3A), School of Engineering & Architecture, University of Zaragoza, 50018 Zaragoza, Aragon, Spain
| | - Hippolyte Amaveda
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC and University of Zaragoza, 50018 Zaragoza, Aragon, Spain
| | - Mario Mora
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC and University of Zaragoza, 50018 Zaragoza, Aragon, Spain
| | - Carlos Marcuello
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC and University of Zaragoza, 50018 Zaragoza, Aragon, Spain
- Laboratorio de Microscopías Avanzadas (LMA), University of Zaragoza, 50018 Zaragoza, Aragon, Spain
| | - Anabel Lostao
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC and University of Zaragoza, 50018 Zaragoza, Aragon, Spain
- Laboratorio de Microscopías Avanzadas (LMA), University of Zaragoza, 50018 Zaragoza, Aragon, Spain
- Fundación ARAID, 50018 Zaragoza, Aragon, Spain
| | - Pilar Alamán-Díez
- Multiscale in Mechanical & Biological Engineering Research Group, Aragon Institute of Engineering Research (I3A), School of Engineering & Architecture, University of Zaragoza, 50018 Zaragoza, Aragon, Spain
| | - Salvador Pérez-Huertas
- Department of Chemical Engineering, Faculty of Sciences, University of Granada, 18071 Granada, Andalusia, Spain
| | - María Ángeles Pérez
- Multiscale in Mechanical & Biological Engineering Research Group, Aragon Institute of Engineering Research (I3A), School of Engineering & Architecture, University of Zaragoza, 50018 Zaragoza, Aragon, Spain
- Aragon Institute for Health Research (IIS Aragon), Miguel Servet University Hospital, 50009 Zaragoza, Aragon, Spain
| | - José Manuel García-Aznar
- Multiscale in Mechanical & Biological Engineering Research Group, Aragon Institute of Engineering Research (I3A), School of Engineering & Architecture, University of Zaragoza, 50018 Zaragoza, Aragon, Spain
- Aragon Institute for Health Research (IIS Aragon), Miguel Servet University Hospital, 50009 Zaragoza, Aragon, Spain
| | - Elena García-Gareta
- Multiscale in Mechanical & Biological Engineering Research Group, Aragon Institute of Engineering Research (I3A), School of Engineering & Architecture, University of Zaragoza, 50018 Zaragoza, Aragon, Spain
- Aragon Institute for Health Research (IIS Aragon), Miguel Servet University Hospital, 50009 Zaragoza, Aragon, Spain
- Division of Biomaterials & Tissue Engineering, UCL Eastman Dental Institute, University College London, London NW3 2PF, UK
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Longtine AG, Venkatasubramanian R, Zigler MC, Lindquist AJ, Mahoney SA, Greenberg NT, VanDongen NS, Ludwig KR, Moreau KL, Seals DR, Clayton ZS. Female C57BL/6N mice are a viable model of aortic aging in women. Am J Physiol Heart Circ Physiol 2023; 324:H893-H904. [PMID: 37115626 PMCID: PMC10202480 DOI: 10.1152/ajpheart.00120.2023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/20/2023] [Accepted: 04/21/2023] [Indexed: 04/29/2023]
Abstract
The aorta stiffens with aging in both men and women, which predicts cardiovascular mortality. Aortic wall structural and extracellular matrix (ECM) remodeling, induced in part by chronic low-grade inflammation, contribute to aortic stiffening. Male mice are an established model of aortic aging. However, there is little information regarding whether female mice are an appropriate model of aortic aging in women, which we aimed to elucidate in the present study. We assessed two strains of mice and found that in C57BL/6N mice, in vivo aortic stiffness (pulse wave velocity, PWV) was higher with aging in both sexes, whereas in B6D2F1 mice, PWV was higher in old versus young male mice, but not in old versus young female mice. Because the age-related stiffening that occurs in men and women was reflected in male and female C57BL/6N mice, we examined the mechanisms of stiffening in this strain. In both sexes, aortic modulus of elasticity (pin myography) was lower in old mice, occurred in conjunction with and was related to higher plasma levels of the elastin-degrading enzyme matrix metalloproteinase-9 (MMP-9), and was accompanied by higher numbers of aortic elastin breaks and higher abundance of adventitial collagen-1. Plasma levels of the inflammatory cytokines interferon-γ, interleukin 6, and monocyte chemoattractant protein-1 were higher in both sexes of old mice. In conclusion, female C57BL/6N mice exhibit aortic stiffening, reduced modulus of elasticity and structural/ECM remodeling, and associated increases in MMP-9 and systemic inflammation with aging, and thus are an appropriate model of aortic aging in women.NEW & NOTEWORTHY Our study demonstrates that with aging, female C57BL/6N mice exhibit higher in vivo aortic stiffness, reduced modulus of elasticity, aortic wall structural and extracellular matrix remodeling, and elevations in systemic inflammation. These changes are largely reflective of those that occur with aging in women. Thus, female C57BL/6N mice are a viable model of human aortic aging and the utility of these animals should be considered in future biomedical investigations.
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Affiliation(s)
- Abigail G Longtine
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | | | - Melanie C Zigler
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Alexandra J Lindquist
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Sophia A Mahoney
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Nathan T Greenberg
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Nicholas S VanDongen
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Katelyn R Ludwig
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Kerrie L Moreau
- University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
| | - Douglas R Seals
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
| | - Zachary S Clayton
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States
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Sigaeva T, Zhang Y. A novel constitutive model considering the role of elastic lamellae' structural heterogeneity in homogenizing transmural stress distribution in arteries. J R Soc Interface 2023; 20:20220837. [PMID: 37042193 PMCID: PMC10091191 DOI: 10.1098/rsif.2022.0837] [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: 11/19/2022] [Accepted: 03/21/2023] [Indexed: 04/13/2023] Open
Abstract
Understanding how the homeostatic stress state can be reached in arterial tissues can provide new insights into vascular physiology. Even though the function of maintaining homeostasis is often linked to the concentric layers of medial elastic lamellae, how the lamellae are capable of evenly distributing the stress transmurally remains to be understood. The recent microstructural study by Yu et al. (2018 J. R. Soc. Interface 15, 20180492) revealed that, circumferentially, lamellar layers closer to the lumen are wavier than the ones further away from it and, thus, experience more unfolding when subjected to blood pressure. Motivated by this peculiar finding, the current study, for the first time, proposes a novel approach to model elastic lamellae and such structural heterogeneity using the extensible worm-like chain model. When implemented into the material description of the conventional two-layer artery model, in which adventitial collagen is modelled using the inextensible worm-like chain model, it is demonstrated that structural heterogeneity in elastic lamellae plays an important role in dictating transmural stress distribution and, therefore, the homeostasis of the arterial wall.
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Affiliation(s)
- Taisiya Sigaeva
- Department of Systems Design Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
| | - Yanhang Zhang
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
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10
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Goldman J, Liu SQ, Tefft BJ. Anti-Inflammatory and Anti-Thrombogenic Properties of Arterial Elastic Laminae. Bioengineering (Basel) 2023; 10:bioengineering10040424. [PMID: 37106611 PMCID: PMC10135563 DOI: 10.3390/bioengineering10040424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 03/07/2023] [Accepted: 03/16/2023] [Indexed: 03/30/2023] Open
Abstract
Elastic laminae, an elastin-based, layered extracellular matrix structure in the media of arteries, can inhibit leukocyte adhesion and vascular smooth muscle cell proliferation and migration, exhibiting anti-inflammatory and anti-thrombogenic properties. These properties prevent inflammatory and thrombogenic activities in the arterial media, constituting a mechanism for the maintenance of the structural integrity of the arterial wall in vascular disorders. The biological basis for these properties is the elastin-induced activation of inhibitory signaling pathways, involving the inhibitory cell receptor signal regulatory protein α (SIRPα) and Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP1). The activation of these molecules causes deactivation of cell adhesion- and proliferation-regulatory signaling mechanisms. Given such anti-inflammatory and anti-thrombogenic properties, elastic laminae and elastin-based materials have potential for use in vascular reconstruction.
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11
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Wang Z, Mithieux SM, Vindin H, Wang Y, Zhang M, Liu L, Zbinden J, Blum KM, Yi T, Matsuzaki Y, Oveissi F, Akdemir R, Lockley KM, Zhang L, Ma K, Guan J, Waterhouse A, Pham NTH, Hawkett BS, Shinoka T, Breuer CK, Weiss AS. Rapid Regeneration of a Neoartery with Elastic Lamellae. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2205614. [PMID: 36120809 DOI: 10.1002/adma.202205614] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/24/2022] [Indexed: 06/15/2023]
Abstract
Native arteries contain a distinctive intima-media composed of organized elastin and an adventitia containing mature collagen fibrils. In contrast, implanted biodegradable small-diameter vascular grafts do not present spatially regenerated, organized elastin. The elastin-containing structures within the intima-media region encompass the elastic lamellae (EL) and internal elastic lamina (IEL) and are crucial for normal arterial function. Here, the development of a novel electrospun small-diameter vascular graft that facilitates de novo formation of a structurally appropriate elastin-containing intima-media region following implantation is described. The graft comprises a non-porous microstructure characterized by tropoelastin fibers that are embedded in a PGS matrix. After implantation in mouse abdominal aorta, the graft develops distinct cell and extracellular matrix profiles that approximate the native adventitia and intima-media by 8 weeks. Within the newly formed intima-media region there are circumferentially aligned smooth muscle cell layers that alternate with multiple EL similar to that found in the arterial wall. By 8 months, the developed adventitia region contains mature collagen fibrils and the neoartery presents a distinct IEL with thickness comparable to that in mouse abdominal aorta. It is proposed that this new class of material can generate the critically required, organized elastin needed for arterial regeneration.
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Affiliation(s)
- Ziyu Wang
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
- Charles Perkins Centre, University of Sydney, Sydney, NSW, 2006, Australia
| | - Suzanne M Mithieux
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
- Charles Perkins Centre, University of Sydney, Sydney, NSW, 2006, Australia
| | - Howard Vindin
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
- Charles Perkins Centre, University of Sydney, Sydney, NSW, 2006, Australia
| | - Yiwei Wang
- Burns Research and Reconstructive Surgery, Anzac Research Institute, Sydney, NSW, 2139, Australia
- Jiangsu Provincial Engineering Research Centre of TCM External Medication Development and Application, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, 210023, China
| | - Miao Zhang
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
- Charles Perkins Centre, University of Sydney, Sydney, NSW, 2006, Australia
| | - Linyang Liu
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
- Charles Perkins Centre, University of Sydney, Sydney, NSW, 2006, Australia
| | - Jacob Zbinden
- Center for Regenerative Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, 43215, USA
| | - Kevin M Blum
- Center for Regenerative Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, 43215, USA
| | - Tai Yi
- Center for Regenerative Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, 43215, USA
| | - Yuichi Matsuzaki
- Center for Regenerative Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, 43215, USA
| | - Farshad Oveissi
- School of Chemical and Biomolecular Engineering, University of Sydney, Sydney, NSW, 2006, Australia
| | - Reyda Akdemir
- Department of Chemical Engineering, University Rovira i Virgili, Tarragona, E-43007, Spain
| | - Karen M Lockley
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
- Charles Perkins Centre, University of Sydney, Sydney, NSW, 2006, Australia
| | - Lingyue Zhang
- International Research Center for Advanced Structural and Biomaterials, School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Ke Ma
- International Research Center for Advanced Structural and Biomaterials, School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Juan Guan
- International Research Center for Advanced Structural and Biomaterials, School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Anna Waterhouse
- Charles Perkins Centre, University of Sydney, Sydney, NSW, 2006, Australia
- School of Medical Science, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, 2006, Australia
- The Heart Research Institute, University of Sydney, Sydney, NSW, 204206, Australia
- The University of Sydney Nano Institute, University of Sydney, Sydney, NSW, 2006, Australia
| | - Nguyen T H Pham
- Key Centre for Polymers and Colloids, School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia
| | - Brian S Hawkett
- The University of Sydney Nano Institute, University of Sydney, Sydney, NSW, 2006, Australia
- Key Centre for Polymers and Colloids, School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia
| | - Toshiharu Shinoka
- Center for Regenerative Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, 43215, USA
| | - Christopher K Breuer
- Center for Regenerative Medicine, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, 43215, USA
| | - Anthony S Weiss
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
- Charles Perkins Centre, University of Sydney, Sydney, NSW, 2006, Australia
- The University of Sydney Nano Institute, University of Sydney, Sydney, NSW, 2006, Australia
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12
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Linka K, Cavinato C, Humphrey JD, Cyron CJ. Predicting and understanding arterial elasticity from key microstructural features by bidirectional deep learning. Acta Biomater 2022; 147:63-72. [PMID: 35643194 DOI: 10.1016/j.actbio.2022.05.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 05/19/2022] [Accepted: 05/19/2022] [Indexed: 01/15/2023]
Abstract
Microstructural features and mechanical properties are closely related in all soft biological tissues. Both yet exhibit considerable inter-individual differences and are affected by factors such as aging and disease and its progression. Histological analysis, modern in situ imaging, and biomechanical testing have deepened our understanding of these complex interrelations, yet two key questions remain: (1) Given the specific microstructure, can one predict the macroscopic mechanical properties without mechanical testing? (2) Can one quantify individual contributions of the different microstructural features to the macroscopic mechanical properties in an automated, systematic and largely unbiased way? Here we propose a bidirectional deep learning architecture to address these two questions. Our architecture uses data from standard histological analyses, two-photon microscopy and biaxial biomechanical testing. Its capabilities are demonstrated by predicting with high accuracy (R2=0.92) the evolving mechanical properties of the murine aorta during maturation and aging. Moreover, our architecture reveals that the extracellular matrix composition and organization are the most prominent factors governing the macroscopic mechanical properties of the tissues studied herein. STATEMENT OF SIGNIFICANCE: .
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Affiliation(s)
- Kevin Linka
- Institute for Continuum and Material Mechanics, Hamburg University of Technology, Hamburg, Germany
| | - Cristina Cavinato
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA; Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, USA
| | - Christian J Cyron
- Institute for Continuum and Material Mechanics, Hamburg University of Technology, Hamburg, Germany; Institute of Material Systems Modeling, Helmholtz-Zentrum Hereon, Geesthacht, Germany.
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13
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Through the cleared aorta: three-dimensional characterization of mechanical behaviors of rat thoracic aorta under intraluminal pressurization using optical clearing method. Sci Rep 2022; 12:8632. [PMID: 35606390 PMCID: PMC9126909 DOI: 10.1038/s41598-022-12429-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 05/09/2022] [Indexed: 11/22/2022] Open
Abstract
The media of aortic wall is characterized by altering layers of elastin and smooth muscle cells (SMCs), along with collagen fibers in both layers, and plays a central role in functional and pathological remodeling such as hypertension and atherosclerosis. Because the arterial function is linked closely to the arterial wall internal structure, it is essential to investigate the alteration of the arterial microstructure during macroscopic deformation to understand cardiovascular pathologies. The present study adopted a tissue clearing method in three-dimensional mechanical characterization of rat thoracic aorta, and successfully observed changes in the structure of each of the three primary components of the aorta under intraluminal pressurization while maintaining tissue mechanical integrity and flexibility. Layers of elastic fibers and SMCs deformed greater on the intimal side than those on the adventitial side. Furthermore, there was a structural agreement in the alignment angle between SMC nuclei and elastic fibers on their intimal side, but not on the adventitial side. This is the first study that changes in the microstructure of three primary components of the aorta were visualized and evaluated through the aorta. The method established here would also be useful to understand tissue mechanics of other load-bearing soft tissues.
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14
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Yin M, Ban E, Rego BV, Zhang E, Cavinato C, Humphrey JD, Em Karniadakis G. Simulating progressive intramural damage leading to aortic dissection using DeepONet: an operator-regression neural network. J R Soc Interface 2022; 19:20210670. [PMID: 35135299 PMCID: PMC8826120 DOI: 10.1098/rsif.2021.0670] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 12/23/2021] [Indexed: 12/28/2022] Open
Abstract
Aortic dissection progresses mainly via delamination of the medial layer of the wall. Notwithstanding the complexity of this process, insight has been gleaned by studying in vitro and in silico the progression of dissection driven by quasi-static pressurization of the intramural space by fluid injection, which demonstrates that the differential propensity of dissection along the aorta can be affected by spatial distributions of structurally significant interlamellar struts that connect adjacent elastic lamellae. In particular, diverse histological microstructures may lead to differential mechanical behaviour during dissection, including the pressure-volume relationship of the injected fluid and the displacement field between adjacent lamellae. In this study, we develop a data-driven surrogate model of the delamination process for differential strut distributions using DeepONet, a new operator-regression neural network. This surrogate model is trained to predict the pressure-volume curve of the injected fluid and the damage progression within the wall given a spatial distribution of struts, with in silico data generated using a phase-field finite-element model. The results show that DeepONet can provide accurate predictions for diverse strut distributions, indicating that this composite branch-trunk neural network can effectively extract the underlying functional relationship between distinctive microstructures and their mechanical properties. More broadly, DeepONet can facilitate surrogate model-based analyses to quantify biological variability, improve inverse design and predict mechanical properties based on multi-modality experimental data.
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Affiliation(s)
- Minglang Yin
- Center for Biomedical Engineering, Brown University, Providence, RI 02912, USA
- School of Engineering, Brown University, Providence, RI 02912, USA
| | - Ehsan Ban
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA
| | - Bruno V. Rego
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA
| | - Enrui Zhang
- Division of Applied Mathematics, Brown University, Providence, RI 02912, USA
| | - Cristina Cavinato
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA
| | - Jay D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA
| | - George Em Karniadakis
- School of Engineering, Brown University, Providence, RI 02912, USA
- Division of Applied Mathematics, Brown University, Providence, RI 02912, USA
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15
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Cavinato C, Chen M, Weiss D, Ruiz-Rodríguez MJ, Schwartz MA, Humphrey JD. Progressive Microstructural Deterioration Dictates Evolving Biomechanical Dysfunction in the Marfan Aorta. Front Cardiovasc Med 2021; 8:800730. [PMID: 34977201 PMCID: PMC8716484 DOI: 10.3389/fcvm.2021.800730] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Accepted: 11/23/2021] [Indexed: 11/13/2022] Open
Abstract
Medial deterioration leading to thoracic aortic aneurysms arises from multiple causes, chief among them mutations to the gene that encodes fibrillin-1 and leads to Marfan syndrome. Fibrillin-1 microfibrils associate with elastin to form elastic fibers, which are essential structural, functional, and instructional components of the normal aortic wall. Compromised elastic fibers adversely impact overall structural integrity and alter smooth muscle cell phenotype. Despite significant progress in characterizing clinical, histopathological, and mechanical aspects of fibrillin-1 related aortopathies, a direct correlation between the progression of microstructural defects and the associated mechanical properties that dictate aortic functionality remains wanting. In this paper, age-matched wild-type, Fbn1 C1041G/+, and Fbn1 mgR/mgR mouse models were selected to represent three stages of increasing severity of the Marfan aortic phenotype. Ex vivo multiphoton imaging and biaxial mechanical testing of the ascending and descending thoracic aorta under physiological loading conditions demonstrated that elastic fiber defects, collagen fiber remodeling, and cell reorganization increase with increasing dilatation. Three-dimensional microstructural characterization further revealed radial patterns of medial degeneration that become more uniform with increasing dilatation while correlating strongly with increased circumferential material stiffness and decreased elastic energy storage, both of which comprise aortic functionality.
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Affiliation(s)
- Cristina Cavinato
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States
| | - Minghao Chen
- Cardiovascular Research Center and Department of Internal Medicine (Cardiology), Yale School of Medicine, New Haven, CT, United States
| | - Dar Weiss
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States
| | - Maria Jesús Ruiz-Rodríguez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC) and Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - Martin A. Schwartz
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States
- Cardiovascular Research Center and Department of Internal Medicine (Cardiology), Yale School of Medicine, New Haven, CT, United States
| | - Jay D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States
- Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, United States
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16
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He X, Auricchio F, Morganti S, Lu J. Uniaxial properties of ascending aortic aneurysms in light of effective stretch. Acta Biomater 2021; 136:306-313. [PMID: 34560300 DOI: 10.1016/j.actbio.2021.09.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/07/2021] [Accepted: 09/16/2021] [Indexed: 01/15/2023]
Abstract
A constitutive model that explicitly considers the gradual recruitment of collagen fibers is applied to investigate the uniaxial properties of human ascending aortic aneurysms. The model uses an effective stretch, which is a continuum scale kinematic variable measuring the true stretch of the tissue, to formulate the fiber stress. The constitutive equation contains two shape parameters characterizing the stochastic distribution of fiber waviness, and two elastic parameters accounting for, respectively, the elastic properties of ground substance and the straightened collagen fibers. The model is applied to 156 sets of uniaxial stress-stretch data obtained from 52 aneurysm samples. Major findings include (1) the uniaxial response can be well described by a quadratic strain energy function of the effective strain; (2) the ultimate stretches, when measured in terms of the effective stretch, are closely clustered around 1.1, in contrast to a much wider range in the original stretch; and (3) the ultimate stress correlates positively with the fiber stiffness. The age dependence and directional differences of constitutive parameters are also investigated. Results indicate that only the waviness depends strongly on age; no clear alterations occur in elastic parameters. Further, the fibers are wavier and stiffer in the circumferential direction than in the longitudinal direction. No other parameters exhibit significant direction difference. STATEMENT OF SIGNIFICANCE: We introduced a constitutive model which explicitly accounts for collagen fiber recruitment to investigate the uniaxial properties of human ascending aortic aneurysm tissues. Uniaxial response data from 156 specimens were considered in the study. It was found that the seemingly dissimilar response curves are, in fact, similar if we measure the deformation using an effective stretch which factors out the uncrimping deformation. The rupture stretches in terms of the effective stretch are closely packed around 1.1. And the stress-stretch curves collapse to a canonical curve after a transformation.
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Affiliation(s)
- Xuehuan He
- Department of Mechanical Engineering, The University of Iowa, Iowa City, IA 52242, USA
| | - Ferdinando Auricchio
- Department of Civil Engineering and Architecture, University of Pavia, Pavia 27100, Italy
| | - Simone Morganti
- Department of Electrical, Computer, and Biomedical Engineering, University of Pavia, Pavia 27100, Italy
| | - Jia Lu
- Department of Mechanical Engineering, The University of Iowa, Iowa City, IA 52242, USA.
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17
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Cavinato C, Murtada SI, Rojas A, Humphrey JD. Evolving structure-function relations during aortic maturation and aging revealed by multiphoton microscopy. Mech Ageing Dev 2021; 196:111471. [PMID: 33741396 PMCID: PMC8154707 DOI: 10.1016/j.mad.2021.111471] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 03/11/2021] [Accepted: 03/14/2021] [Indexed: 12/30/2022]
Abstract
The evolving microstructure and mechanical properties that promote homeostasis in the aorta are fundamental to age-specific adaptations and disease progression. We combine ex vivo multiphoton microscopy and biaxial biomechanical phenotyping to quantify and correlate layer-specific microstructural parameters, for the primary extracellular matrix components (fibrillar collagen and elastic lamellae) and cells (endothelial, smooth muscle, and adventitial), with mechanical properties of the mouse aorta from weaning through natural aging up to one year. The aging endothelium was characterized by progressive reductions in cell density and altered cellular orientation. The media similarly showed a progressive decrease in smooth muscle cell density and alignment though with inter-lamellar widening from intermediate to older ages, suggesting cell hypertrophy, matrix accumulation, or both. Despite not changing in tissue thickness, the aging adventitia exhibited a marked thickening and straightening of collagen fiber bundles and reduction in cell density, suggestive of age-related remodeling not growth. Multiple microstructural changes correlated with age-related increases in circumferential and axial material stiffness, among other mechanical metrics. Because of the importance of aging as a risk factor for cardiovascular diseases, understanding the normal progression of structural and functional changes is essential when evaluating superimposed disease-related changes as a function of the age of onset.
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Affiliation(s)
- Cristina Cavinato
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Sae-Il Murtada
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Alexia Rojas
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Jay D Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA; Vascular Biology and Therapeutics Program, Yale School of Medicine, New Haven, CT, USA.
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18
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Creamer TJ, Bramel EE, MacFarlane EG. Insights on the Pathogenesis of Aneurysm through the Study of Hereditary Aortopathies. Genes (Basel) 2021; 12:183. [PMID: 33514025 PMCID: PMC7912671 DOI: 10.3390/genes12020183] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/20/2021] [Accepted: 01/22/2021] [Indexed: 12/15/2022] Open
Abstract
Thoracic aortic aneurysms (TAA) are permanent and localized dilations of the aorta that predispose patients to a life-threatening risk of aortic dissection or rupture. The identification of pathogenic variants that cause hereditary forms of TAA has delineated fundamental molecular processes required to maintain aortic homeostasis. Vascular smooth muscle cells (VSMCs) elaborate and remodel the extracellular matrix (ECM) in response to mechanical and biochemical cues from their environment. Causal variants for hereditary forms of aneurysm compromise the function of gene products involved in the transmission or interpretation of these signals, initiating processes that eventually lead to degeneration and mechanical failure of the vessel. These include mutations that interfere with transduction of stimuli from the matrix to the actin-myosin cytoskeleton through integrins, and those that impair signaling pathways activated by transforming growth factor-β (TGF-β). In this review, we summarize the features of the healthy aortic wall, the major pathways involved in the modulation of VSMC phenotypes, and the basic molecular functions impaired by TAA-associated mutations. We also discuss how the heterogeneity and balance of adaptive and maladaptive responses to the initial genetic insult might contribute to disease.
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Affiliation(s)
- Tyler J. Creamer
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; (T.J.C.); (E.E.B.)
- Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Emily E. Bramel
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; (T.J.C.); (E.E.B.)
- Predoctoral Training in Human Genetics and Molecular Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Elena Gallo MacFarlane
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; (T.J.C.); (E.E.B.)
- Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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19
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Wang R, Yu X, Gkousioudi A, Zhang Y. Effect of Glycation on Interlamellar Bonding of Arterial Elastin. EXPERIMENTAL MECHANICS 2021; 61:81-94. [PMID: 33583947 PMCID: PMC7880226 DOI: 10.1007/s11340-020-00644-y] [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: 03/04/2020] [Accepted: 07/21/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND Interlamellar bonding in the arterial wall is often compromised by cardiovascular diseases. However, several recent nationwide and hospital-based studies have uniformly reported reduced risk of thoracic aortic dissection in patients with diabetes. As one of the primary structural constituents in the arterial wall, elastin plays an important role in providing its interlamellar structural integrity. OBJECTIVE The purpose of this study is to examine the effects of glycation on the interlamellar bonding properties of arterial elastin. METHODS Purified elastin network was isolated from porcine descending thoracic aorta and incubated in 2 M glucose solution for 7, 14 or 21 days at 37 °C. Peeling and direct tension tests were performed to provide complimentary information on understanding the interlamellar layer separation properties of elastin network with glycation effect. Peeling tests were simulated using a cohesive zone model (CZM). Multiphoton imaging was used to visualize the interlamellar elastin fibers in samples subjected to peeling and direct tension. RESULTS Peeling and direct tension tests show that interlamellar energy release rate and strength both increases with the duration of glucose treatment. The traction at damage initiation estimated for the CZM agrees well with the interlamellar strength measurements from direct tension tests. Glycation was also found to increase the interlamellar failure strain of arterial elastin. Multiphoton imaging confirmed the contribution of radially running elastin fibers to resisting dissection. CONCLUSIONS Nonenzymatic glycation reduces the propensity of arterial elastin to dissection. This study also suggests that the CZM effectively describes the interlamellar bonding properties of arterial elastin.
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Affiliation(s)
- R Wang
- Department of Mechanical Engineering, Boston University, Boston, MA 02215
| | - X Yu
- Department of Mechanical Engineering, Boston University, Boston, MA 02215
| | - A Gkousioudi
- Department of Mechanical Engineering, Boston University, Boston, MA 02215
| | - Y Zhang
- Department of Mechanical Engineering, Boston University, Boston, MA 02215
- Department of Biomedical Engineering, Boston University, Boston, MA 02215
- Divison of Materials Science & Engineering, Boston University, Boston, MA 02215
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20
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Wang R, Yu X, Zhang Y. Mechanical and structural contributions of elastin and collagen fibers to interlamellar bonding in the arterial wall. Biomech Model Mechanobiol 2020; 20:93-106. [PMID: 32705413 DOI: 10.1007/s10237-020-01370-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 07/15/2020] [Indexed: 12/25/2022]
Abstract
The artery relies on interlamellar structural components, mainly elastin and collagen fibers, for maintaining its integrity and resisting dissection propagation. In this study, the contribution of arterial elastin and collagen fibers to interlamellar bonding was studied through mechanical testing, multiphoton imaging and finite element modeling. Steady-state peeling experiments were performed on porcine aortic media and the purified elastin network in the circumferential (Circ) and longitudinal (Long) directions. The peeling force and energy release rate associated with mode-I failure are much higher for aortic media than for the elastin network. Also, longitudinal peeling exhibits a higher energy release rate and strength than circumferential peeling for both the aortic media and elastin. Multiphoton imaging shows the recruitment of both elastin and collagen fibers within the interlamellar space and points to in-plane anisotropy of fiber distributions as a potential mechanism for the direction-dependent phenomena of peeling tests. Three-dimensional finite element models based on cohesive zone model (CZM) of fracture were created to simulate the peeling tests with the interlamellar energy release rate and separation distance at damage initiation obtained directly from peeling test. Our experimental results show that the separation distance at damage initiation is 80 μm for aortic media and 40 μm for elastin. The damage initiation stress was estimated from the model for aortic media (Circ: 60 kPa; Long: 95 kPa) and elastin (Circ: 9 kPa; Long: 14 kPa). The interlamellar separation distance at complete failure was estimated to be 3 - 4 mm for both media and elastin. Furthermore, elastin and collagen fibers both play an important role in bonding of the arterial wall, while collagen has a higher contribution than elastin to interlamellar stiffness, strength and toughness. These results on microstructural interlamellar failure shed light on the pathological development and progression of aortic dissection.
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Affiliation(s)
- Ruizhi Wang
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Xunjie Yu
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Yanhang Zhang
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA. .,Department of Biomedical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA. .,Divison of Materials Science & Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA.
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21
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Bardet SM, Cortese J, Blanc R, Mounayer C, Rouchaud A. Multiphoton microscopy for pre-clinical evaluation of flow-diverter stents for treating aneurysms. J Neuroradiol 2020; 48:200-206. [PMID: 32205257 DOI: 10.1016/j.neurad.2020.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 03/09/2020] [Accepted: 03/10/2020] [Indexed: 12/17/2022]
Abstract
BACKGROUND Conventional histological analyses are the gold standard for the study of aneurysms and vascular pathologies in pre-clinical research. Over the past decade, in vivo and ex vivo imaging using multiphoton microscopy have emerged as powerful pre-clinical tools for detailed tissue analyses that can assess morphology, the extracellular matrix (ECM), cell density and vascularisation. Multiphoton microscopy allows for deeper tissue penetration with minor phototoxicity. OBJECTIVE The present study aimed to demonstrate the current status of multimodality imaging, including multiphoton microscopy, for detailed analyses of neo-endothelialisation and ECM evolution after flow-diverter stent (FDS) treatment in an experimental rabbit model of aneurysms. METHODS Multiphoton microscopy tools for assessing autofluorescence and second harmonic generation (SHG) signals from biological tissues were used to evaluate the endovascular treatment of intracranial aneurysms in an animal model of aneurysms (pig, rabbit). Results from multiphoton microscopy were compared to those from standard histology, electronic and bright field microscopy. CONCLUSIONS The present study describes novel evaluation modes based on multiphoton microscopy for visualising tissue morphology (e.g., collagen, elastin, and cells) to qualify and quantify the extent of neo-intimal formation of covered arteries and device integration into the arterial wall using a rabbit model of intracranial aneurysms treated with FDS.
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Affiliation(s)
- Sylvia M Bardet
- University of Limoges, 123, avenue Albert-Thomas, XLIM UMR CNRS 7252, 87060 Limoges, France.
| | - Jonathan Cortese
- Bichat University Hospital, INSERM U1148-LVTS, Paris, France; Bicetre Hospital, Department of Interventional Neuroradiology, Paris, France
| | - Raphaël Blanc
- Department of Interventional Neuroradiology, Fondation Ophtalmologique Adolphe-de-Rothschild, Paris, France
| | - Charbel Mounayer
- University of Limoges, 123, avenue Albert-Thomas, XLIM UMR CNRS 7252, 87060 Limoges, France; University Hospital, Department of Interventional Neuroradiology, Limoges, France
| | - Aymeric Rouchaud
- University of Limoges, 123, avenue Albert-Thomas, XLIM UMR CNRS 7252, 87060 Limoges, France; University Hospital, Department of Interventional Neuroradiology, Limoges, France.
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Trachet B, Ferraro M, Lovric G, Aslanidou L, Logghe G, Segers P, Stergiopulos N. Synchrotron-based visualization and segmentation of elastic lamellae in the mouse carotid artery during quasi-static pressure inflation. J R Soc Interface 2019; 16:20190179. [PMID: 31238834 DOI: 10.1098/rsif.2019.0179] [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] [Indexed: 12/18/2022] Open
Abstract
In computational aortic biomechanics, aortic and arterial tissue are typically modelled as a homogeneous layer, making abstraction not only of the layered structure of intima, media and adventitia but also of the microstructure that exists within these layers. Here, we present a novel method to visualize the microstructure of the tunica media along the entire circumference of the vessel. To that end, we developed a pressure-inflation device that is compatible with synchrotron-based phase-contrast imaging. Using freshly excised left common carotid arteries from n = 12 mice, we visualized how the lamellae and interlamellar layers inflate as the luminal pressure is increased from 0 to 120 mm Hg in quasi-static steps. A graph-based segmentation algorithm subsequently allowed us to automatically segment each of the three lamellae, resulting in a three-dimensional geometry that represents lamellae, interlamellar layers and adventitia at nine different pressure levels. Our results demonstrate that the three elastic lamellae unfold and stretch simultaneously as luminal pressure is increased. In the long term, we believe that the results presented in this work can be a first step towards a better understanding of the mechanics of the arterial microstructure.
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Affiliation(s)
- Bram Trachet
- 1 Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne , Lausanne , Switzerland.,2 IBiTech-bioMMeda , Ghent University, Ghent , Belgium
| | - Mauro Ferraro
- 1 Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne , Lausanne , Switzerland
| | - Goran Lovric
- 3 Centre d'Imagerie BioMédicale, Ecole Polytechnique Fédérale de Lausanne , Lausanne , Switzerland.,4 Swiss Light Source, Paul Scherrer Institute , Villigen , Switzerland
| | - Lydia Aslanidou
- 1 Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne , Lausanne , Switzerland
| | | | | | - Nikolaos Stergiopulos
- 1 Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne , Lausanne , Switzerland
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