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Trębacz H, Barzycka A. Mechanical Properties and Functions of Elastin: An Overview. Biomolecules 2023; 13:biom13030574. [PMID: 36979509 PMCID: PMC10046833 DOI: 10.3390/biom13030574] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/08/2023] [Accepted: 03/20/2023] [Indexed: 03/30/2023] Open
Abstract
Human tissues must be elastic, much like other materials that work under continuous loads without losing functionality. The elasticity of tissues is provided by elastin, a unique protein of the extracellular matrix (ECM) of mammals. Its function is to endow soft tissues with low stiffness, high and fully reversible extensibility, and efficient elastic-energy storage. Depending on the mechanical functions, the amount and distribution of elastin-rich elastic fibers vary between and within tissues and organs. The article presents a concise overview of the mechanical properties of elastin and its role in the elasticity of soft tissues. Both the occurrence of elastin and the relationship between its spatial arrangement and mechanical functions in a given tissue or organ are overviewed. As elastin in tissues occurs only in the form of elastic fibers, the current state of knowledge about their mechanical characteristics, as well as certain aspects of degradation of these fibers and their mechanical performance, is presented. The overview also outlines the latest understanding of the molecular basis of unique physical characteristics of elastin and, in particular, the origin of the driving force of elastic recoil after stretching.
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Affiliation(s)
- Hanna Trębacz
- Department of Biophysics, Medical University of Lublin, Al. Racławickie 1, 20-059 Lublin, Poland
| | - Angelika Barzycka
- Department of Biophysics, Medical University of Lublin, Al. Racławickie 1, 20-059 Lublin, Poland
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2
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Chick CN, Inoue T, Mori N, Tanaka E, Kawaguchi M, Takahashi T, Hanakita J, Minami M, Kanematsu R, Usuki T. LC-MS/MS analysis of elastin crosslinker desmosines and microscopic evaluation in clinical samples of patients with hypertrophy of ligamentum flavum. Bioorg Med Chem 2023; 82:117216. [PMID: 36842401 DOI: 10.1016/j.bmc.2023.117216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 02/15/2023] [Accepted: 02/16/2023] [Indexed: 02/23/2023]
Abstract
Ligamentum flavum (LF) pathologies often lead to severe myelopathy or radiculopathy characterized by reduced elasticity, obvious thickening, or worsened ossification. Elastin endows critical mechanical properties to tissues and organs such as vertebrae and ligaments. Desmosine (DES) and isodesmosine (IDES) are crosslinkers of elastin monomers called tropoelastin. These crosslinkers are potential biomarkers of chronic obstructive pulmonary disease. As a biological diagnostic tool that supplements existing symptomatic, magnetic resonance imaging scanning or radiological imaging diagnostic measures for LF hypertrophy and associated pathologies, an isotope-dilution liquid chromatography-tandem mass spectrometry method with selected reaction monitoring mode for the quantitation of DESs in human plasma, urine, cerebrospinal fluid (CSF), and yellow ligamentum was investigated. Isotopically labeled IDES-13C3,15N1 was used as an internal standard (ISTD) for DES quantitation for the first time. The samples plus ISTD were hydrolyzed with 6 N hydrochloric acid. Analytes and ISTD were extracted using a solid phase extraction cellulose cartridge column. The assays were repeatable, reproducible, and accurate with % CV ≤ 7.7, ISTD area % RSD of 7.6, and % AC ≤ (101.2 ± 3.90) of the calibrations. The ligamentum samples gave the highest average DES/IDES content (2.38 μg/mg) on a dry-weight basis. A high percentage of the CSF samples showed almost no DESs. Urine and plasma samples of patients showed no significant difference from the control (p-value = 0.0519 and 0.5707, respectively). Microscopy of the yellow ligamentum samples revealed dark or blue-colored zones of elastin fibers that retained the hematoxylin dye and highly red-colored zones of collagen after counterstaining with van Gieson solution. Thus, we successfully developed a method for DES/IDES quantitation in clinical samples.
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Affiliation(s)
- Christian Nanga Chick
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan
| | - Tomoo Inoue
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan; Department of Neurosurgery, Saitama Red Cross Hospital, 1-5 Shintoshin, Chuo-ku, Saitama 330-8553, Japan; Spinal Disorders Center, Fujieda Heisei Memorial Hospital, 123-1 Mizukami, Fujieda, Shizuoka 426-8662, Japan.
| | - Natsuki Mori
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan
| | - Eri Tanaka
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan
| | - Mari Kawaguchi
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan
| | - Toshiyuki Takahashi
- Spinal Disorders Center, Fujieda Heisei Memorial Hospital, 123-1 Mizukami, Fujieda, Shizuoka 426-8662, Japan
| | - Junya Hanakita
- Spinal Disorders Center, Fujieda Heisei Memorial Hospital, 123-1 Mizukami, Fujieda, Shizuoka 426-8662, Japan
| | - Manabu Minami
- Spinal Disorders Center, Fujieda Heisei Memorial Hospital, 123-1 Mizukami, Fujieda, Shizuoka 426-8662, Japan
| | - Ryo Kanematsu
- Spinal Disorders Center, Fujieda Heisei Memorial Hospital, 123-1 Mizukami, Fujieda, Shizuoka 426-8662, Japan
| | - Toyonobu Usuki
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan.
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Cyril D, Giugni A, Bangar SS, Mirzaeipoueinak M, Shrivastav D, Sharabi M, Tipper JL, Tavakoli J. Elastic Fibers in the Intervertebral Disc: From Form to Function and toward Regeneration. Int J Mol Sci 2022; 23:8931. [PMID: 36012198 PMCID: PMC9408956 DOI: 10.3390/ijms23168931] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/05/2022] [Accepted: 08/08/2022] [Indexed: 11/16/2022] Open
Abstract
Despite extensive efforts over the past 40 years, there is still a significant gap in knowledge of the characteristics of elastic fibers in the intervertebral disc (IVD). More studies are required to clarify the potential contribution of elastic fibers to the IVD (healthy and diseased) function and recommend critical areas for future investigations. On the other hand, current IVD in-vitro models are not true reflections of the complex biological IVD tissue and the role of elastic fibers has often been ignored in developing relevant tissue-engineered scaffolds and realistic computational models. This has affected the progress of IVD studies (tissue engineering solutions, biomechanics, fundamental biology) and translation into clinical practice. Motivated by the current gap, the current review paper presents a comprehensive study (from the early 1980s to 2022) that explores the current understanding of structural (multi-scale hierarchy), biological (development and aging, elastin content, and cell-fiber interaction), and biomechanical properties of the IVD elastic fibers, and provides new insights into future investigations in this domain.
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Affiliation(s)
- Divya Cyril
- Centre for Health Technologies, School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Amelia Giugni
- Centre for Health Technologies, School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Saie Sunil Bangar
- Faculty of Science, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Melika Mirzaeipoueinak
- Centre for Health Technologies, School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Dipika Shrivastav
- Centre for Health Technologies, School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Mirit Sharabi
- Department of Mechanical Engineering and Mechatronics, Ariel University, Ariel 407000, Israel
| | - Joanne L. Tipper
- Centre for Health Technologies, School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Javad Tavakoli
- Centre for Health Technologies, School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW 2007, Australia
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Yang M, Xiang D, Chen Y, Cui Y, Wang S, Liu W. An Artificial PVA-BC Composite That Mimics the Biomechanical Properties and Structure of a Natural Intervertebral Disc. MATERIALS 2022; 15:ma15041481. [PMID: 35208022 PMCID: PMC8875496 DOI: 10.3390/ma15041481] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/26/2022] [Accepted: 02/11/2022] [Indexed: 02/06/2023]
Abstract
Disc herniation is one of the most ubiquitous healthcare problems in modern cities—severe patients eventually require surgical intervention. However, the existing operations—spinal fusion and artificial disc replacement—alter the biomechanics of the spine, leaving much room for improvement. The appropriateness of polyvinyl alcohol (PVA) for biomedical applications has been recognised due to its high water content, excellent biocompatibility, and versatile mechanical properties. In this study, a newly-designed PVA–bacterial cellulose (PVA-BC) composite was assembled to mimic both the biomechanics and annular structure of natural intervertebral discs (IVDs). PVA-BC composites of various concentrations were fabricated and tested under unconfined compression and compressive creep in order to acquire the values of the normalised compressive stiffness and whole normalised deformation. The normalised compressive stiffness increased considerably with an increasing PVA concentration, spanning from 1.82 (±0.18) to 3.50 (±0.14) MPa, and the whole normalised deformation decreased from 0.25 to 0.13. Formulations of 40% PVA provided the most accurate mimicry of natural human IVDs in normalised whole deformation, and demonstrated higher dimensional stability. The biocompatible results further confirmed that the materials had excellent biocompatibility. The novel bionic structure and formulations of the PVA-BC materials mimicked the biomechanics and structure of natural IVDs, and ensured dimensional stability under prolonged compression, reducing the risk of impingement on the surrounding tissue. The PVA-BC composite is a promising material for third-generation artificial IVDs with integrated construction.
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Affiliation(s)
- Mengying Yang
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China; (M.Y.); (Y.C.); (Y.C.)
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
- Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
| | - Dingding Xiang
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
- Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819, China
- Correspondence: (D.X.); (S.W.); (W.L.)
| | - Yuru Chen
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China; (M.Y.); (Y.C.); (Y.C.)
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
- Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
| | - Yangyang Cui
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China; (M.Y.); (Y.C.); (Y.C.)
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
- Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
| | - Song Wang
- Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
- Correspondence: (D.X.); (S.W.); (W.L.)
| | - Weiqiang Liu
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China; (M.Y.); (Y.C.); (Y.C.)
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China
- Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China
- Correspondence: (D.X.); (S.W.); (W.L.)
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Boraldi F, Lofaro FD, Cossarizza A, Quaglino D. The "Elastic Perspective" of SARS-CoV-2 Infection and the Role of Intrinsic and Extrinsic Factors. Int J Mol Sci 2022; 23:ijms23031559. [PMID: 35163482 PMCID: PMC8835950 DOI: 10.3390/ijms23031559] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/20/2022] [Accepted: 01/28/2022] [Indexed: 02/07/2023] Open
Abstract
Elastin represents the structural component of the extracellular matrix providing elastic recoil to tissues such as skin, blood vessels and lungs. Elastogenic cells secrete soluble tropoelastin monomers into the extracellular space where these monomers associate with other matrix proteins (e.g., microfibrils and glycoproteins) and are crosslinked by lysyl oxidase to form insoluble fibres. Once elastic fibres are formed, they are very stable, highly resistant to degradation and have an almost negligible turnover. However, there are circumstances, mainly related to inflammatory conditions, where increased proteolytic degradation of elastic fibres may lead to consequences of major clinical relevance. In severely affected COVID-19 patients, for instance, the massive recruitment and activation of neutrophils is responsible for the profuse release of elastases and other proteolytic enzymes which cause the irreversible degradation of elastic fibres. Within the lungs, destruction of the elastic network may lead to the permanent impairment of pulmonary function, thus suggesting that elastases can be a promising target to preserve the elastic component in COVID-19 patients. Moreover, intrinsic and extrinsic factors additionally contributing to damaging the elastic component and to increasing the spread and severity of SARS-CoV-2 infection are reviewed.
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Affiliation(s)
- Federica Boraldi
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy; (F.B.); (F.D.L.)
| | - Francesco Demetrio Lofaro
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy; (F.B.); (F.D.L.)
| | - Andrea Cossarizza
- Department of Medical and Surgical Sciences for Children and Adults, University of Modena and Reggio Emilia, 41125 Modena, Italy;
| | - Daniela Quaglino
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy; (F.B.); (F.D.L.)
- Correspondence:
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Zou F, Zhang L, Zou X, Huang J, Nie C, Jiang J, Guo C, Wang H, Ma X, Ji M. Differential characterization of lumbar spine associated tissue histology with nonlinear optical microscopy. BIOMEDICAL OPTICS EXPRESS 2022; 13:474-484. [PMID: 35154886 PMCID: PMC8803016 DOI: 10.1364/boe.446351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/12/2021] [Accepted: 12/13/2021] [Indexed: 06/14/2023]
Abstract
Percutaneous endoscopic lumbar discectomy (PELD) is the major effective treatment for lumbar disc herniation, and rapid histological identification of dissected tissue is critical to guide the discectomy. In this work, we revealed the histological features of different types of peridural tissues of the lumbar spine by label-free multi-modal nonlinear optical microscopy. Stimulated Raman scattering (SRS) was used to extract lipid and protein distributions, while second harmonic generation (SHG) and two-photon excited fluorescence (TPEF) signals were applied to image the collagen and elastin fibers at the same time. Our results demonstrated that the nonlinear optical features of the dura and adjacent soft tissues were significantly different, showing the potentials of our method for intraoperative differentiation of these critical tissues and improving the surgical outcome of PELD.
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Affiliation(s)
- Fei Zou
- Department of Orthopaedics, Huashan Hospital, Fudan University, Shanghai 200040, China
- These authors contributed equally
| | - Lili Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Human Phenome Institute, Multiscale Research Institute of Complex Systems, Academy for Engineering and Technology, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai 200433, China
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
- These authors contributed equally
| | - Xiang Zou
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai 200040, China
- These authors contributed equally
| | - Jing Huang
- State Key Laboratory of Surface Physics and Department of Physics, Human Phenome Institute, Multiscale Research Institute of Complex Systems, Academy for Engineering and Technology, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai 200433, China
| | - Cong Nie
- Department of Orthopaedics, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Jianyuan Jiang
- Department of Orthopaedics, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Chongyuan Guo
- Shanghai Starriver Bilingual School, Shanghai 201108, China
| | - Hongli Wang
- Department of Orthopaedics, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Xiaosheng Ma
- Department of Orthopaedics, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Minbiao Ji
- State Key Laboratory of Surface Physics and Department of Physics, Human Phenome Institute, Multiscale Research Institute of Complex Systems, Academy for Engineering and Technology, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai 200433, China
- Yiwu Research Institute of Fudan University, Chengbei Road, Yiwu City, Zhejiang 322000, China
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Schmelzer CEH, Duca L. Elastic fibers: formation, function, and fate during aging and disease. FEBS J 2021; 289:3704-3730. [PMID: 33896108 DOI: 10.1111/febs.15899] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 03/16/2021] [Accepted: 03/22/2021] [Indexed: 01/09/2023]
Abstract
Elastic fibers are extracellular components of higher vertebrates and confer elasticity and resilience to numerous tissues and organs such as large blood vessels, lungs, and skin. Their formation and maturation take place in a complex multistage process called elastogenesis. It requires interactions between very different proteins but also other molecules and leads to the deposition and crosslinking of elastin's precursor on a scaffold of fibrillin-rich microfibrils. Mature fibers are exceptionally resistant to most influences and, under healthy conditions, retain their biomechanical function over the life of the organism. However, due to their longevity, they accumulate damages during aging. These are caused by proteolytic degradation, formation of advanced glycation end products, calcification, oxidative damage, aspartic acid racemization, lipid accumulation, carbamylation, and mechanical fatigue. The resulting changes can lead to diminution or complete loss of elastic fiber function and ultimately affect morbidity and mortality. Particularly, the production of elastokines has been clearly shown to influence several life-threatening diseases. Moreover, the structure, distribution, and abundance of elastic fibers are directly or indirectly influenced by a variety of inherited pathological conditions, which mainly affect organs and tissues such as skin, lungs, or the cardiovascular system. A distinction can be made between microfibril-related inherited diseases that are the result of mutations in diverse microfibril genes and indirectly affect elastogenesis, and elastinopathies that are linked to changes in the elastin gene. This review gives an overview on the formation, structure, and function of elastic fibers and their fate over the human lifespan in health and disease.
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Affiliation(s)
- Christian E H Schmelzer
- Fraunhofer Institute for Microstructure of Materials and Systems IMWS, Halle (Saale), Germany.,Institute of Pharmacy, Faculty of Natural Sciences I, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Laurent Duca
- UMR CNRS 7369 MEDyC, SFR CAP-Sante, Université de Reims Champagne-Ardenne, France
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Ghezelbash F, Eskandari AH, Shirazi-Adl A, Kazempour M, Tavakoli J, Baghani M, Costi JJ. Modeling of human intervertebral disc annulus fibrosus with complex multi-fiber networks. Acta Biomater 2021; 123:208-221. [PMID: 33453409 DOI: 10.1016/j.actbio.2020.12.062] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 12/07/2020] [Accepted: 12/21/2020] [Indexed: 12/21/2022]
Abstract
Collagen fibers within the annulus fibrosus (AF) lamellae are unidirectionally aligned with alternating orientations between adjacent layers. AF constitutive models often combine two adjacent lamellae into a single equivalent layer containing two fiber networks with a crisscross pattern. Additionally, AF models overlook the inter-lamellar matrix (ILM) as well as elastic fiber networks in between lamellae. We developed a nonhomogenous micromechanical model as well as two coarser homogenous hyperelastic and microplane models of the human AF, and compared their performances against measurements (tissue level uniaxial and biaxial tests as well as whole disc experiments) and seven published hyperelastic models. The micromechanical model had a realistic non-homogenous distribution of collagen fiber networks within each lamella and elastic fiber network in the ILM. For small matrix linear moduli (<0.2 MPa), the ILM showed substantial anisotropy (>10%) due to the elastic fiber network. However, at moduli >0.2 MPa, the effects of the elastic fiber network on differences in stress-strain responses at different directions disappeared (<10%). Variations in sample geometry and boundary conditions (due to uncertainty) markedly affected stress-strain responses of the tissue in uniaxial and biaxial tests (up to 16 times). In tissue level tests, therefore, simulations should represent testing conditions (e.g., boundary conditions, specimen geometry, preloads) as closely as possible. Stress/strain fields estimated from the single equivalent layer approach (conventional method) yielded different results from those predicted by the anatomically more accurate apparoach (i.e., layerwise). In addition, in a disc under a compressive force (symmetric loading), asymmetric stress-strain distributions were computed when using a layerwise simulation. Although all developed and selected published AF models predicted gross compression-displacement responses of the whole disc within the range of measured data, some showed excessively stiff or compliant responses under tissue-level uniaxial/biaxial tests. This study emphasizes, when constructing and validating constitutive models of AF, the importance of the proper simulation of individual lamellae as distinct layers, and testing parameters (sample geometric dimensions/loading/boundary conditions).
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Affiliation(s)
- Farshid Ghezelbash
- Department of Mechanical Engineering, Polytechnique Montreal, Quebec, Canada.
| | - Amir Hossein Eskandari
- Institut de recherche Robert Sauvé en santé et en sécurité du travail, Montréal, Québec, Canada
| | | | - Morteza Kazempour
- Mechanical Engineering Department, University of Tehran, Tehran, Iran
| | - Javad Tavakoli
- Centre for Health Technologies, School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, NSW, Australia; SpineLabs, St George & Sutherland Clinical School, The University of New South Wales, NSW, Australia
| | - Mostafa Baghani
- Mechanical Engineering Department, University of Tehran, Tehran, Iran
| | - John J Costi
- Biomechanics and Implants Research Group, Medical Device Research Institute, College of Science and Engineering, Flinders University, Adelaide, Australia
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9
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Material properties of human lumbar intervertebral discs across strain rates. Spine J 2019; 19:2013-2024. [PMID: 31326631 DOI: 10.1016/j.spinee.2019.07.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 07/16/2019] [Accepted: 07/17/2019] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT The use of finite element (FE) methods to study the biomechanics of the intervertebral disc (IVD) has increased over recent decades due to their ability to quantify internal stresses and strains throughout the tissue. Their accuracy is dependent upon realistic, strain-rate dependent material properties, which are challenging to acquire. PURPOSE The aim of this study was to use the inverse FE technique to characterize the material properties of human lumbar IVDs across strain rates. STUDY DESIGN A human cadaveric experimental study coupled with an inverse finite element study. METHODS To predict the structural response of the IVD accurately, the material response of the constituent structures was required. Therefore, compressive experiments were conducted on 16 lumbar IVDs (39±19 years) to obtain the structural response. An FE model of each of these experiments was developed and then run through an inverse FE algorithm to obtain subject-specific constituent material properties, such that the structural response was accurate. RESULTS Experimentally, a log-linear relationship between IVD stiffness and strain rate was observed. The material properties obtained through the subject-specific inverse FE optimization of the annulus fibrosus (AF) fiber and AF fiber ground matrix allowed a good match between the experimental and FE response. This resulted in a Young modulus of AF fibers (-MPa) to strain rate (ε˙, /s) relationship of YMAF=31.5ln(ε˙)+435.5, and the C10 parameter of the Neo-Hookean material model of the AF ground matrix was found to be strain-rate independent with an average value of 0.68 MPa. CONCLUSIONS These material properties can be used to improve the accuracy, and therefore predictive ability of FE models of the spine that are used in a wide range of research areas and clinical applications. CLINICAL SIGNIFICANCE Finite element models can be used for many applications including investigating low back pain, spinal deformities, injury biomechanics, implant design, design of protective systems, and degenerative disc disease. The accurate material properties obtained in this study will improve the predictive ability, and therefore clinical significance of these models.
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10
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A method for visualization and isolation of elastic fibres in annulus fibrosus of the disc. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2018; 93:299-304. [DOI: 10.1016/j.msec.2018.08.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 07/17/2018] [Accepted: 08/03/2018] [Indexed: 01/03/2023]
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11
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Coenen AMJ, Bernaerts KV, Harings JAW, Jockenhoevel S, Ghazanfari S. Elastic materials for tissue engineering applications: Natural, synthetic, and hybrid polymers. Acta Biomater 2018; 79:60-82. [PMID: 30165203 DOI: 10.1016/j.actbio.2018.08.027] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 08/03/2018] [Accepted: 08/21/2018] [Indexed: 02/08/2023]
Abstract
Elastin and collagen are the two main components of elastic tissues and provide the tissue with elasticity and mechanical strength, respectively. Whereas collagen is adequately produced in vitro, production of elastin in tissue-engineered constructs is often inadequate when engineering elastic tissues. Therefore, elasticity has to be artificially introduced into tissue-engineered scaffolds. The elasticity of scaffold materials can be attributed to either natural sources, when native elastin or recombinant techniques are used to provide natural polymers, or synthetic sources, when polymers are synthesized. While synthetic elastomers often lack the biocompatibility needed for tissue engineering applications, the production of natural materials in adequate amounts or with proper mechanical strength remains a challenge. However, combining natural and synthetic materials to create hybrid components could overcome these issues. This review explains the synthesis, mechanical properties, and structure of native elastin as well as the theories on how this extracellular matrix component provides elasticity in vivo. Furthermore, current methods, ranging from proteins and synthetic polymers to hybrid structures that are being investigated for providing elasticity to tissue engineering constructs, are comprehensively discussed. STATEMENT OF SIGNIFICANCE Tissue engineered scaffolds are being developed as treatment options for malfunctioning tissues throughout the body. It is essential that the scaffold is a close mimic of the native tissue with regards to both mechanical and biological functionalities. Therefore, the production of elastic scaffolds is of key importance to fabricate tissue engineered scaffolds of the elastic tissues such as heart valves and blood vessels. Combining naturally derived and synthetic materials to reach this goal proves to be an interesting area where a highly tunable material that unites mechanical and biological functionalities can be obtained.
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Affiliation(s)
- Anna M J Coenen
- Aachen-Maastricht Institute for Biobased Materials (AMIBM), Faculty of Science and Engineering, Maastricht University, Brightlands Chemelot Campus, Urmonderbaan 22, 6167 RD Geleen, The Netherlands
| | - Katrien V Bernaerts
- Aachen-Maastricht Institute for Biobased Materials (AMIBM), Faculty of Science and Engineering, Maastricht University, Brightlands Chemelot Campus, Urmonderbaan 22, 6167 RD Geleen, The Netherlands
| | - Jules A W Harings
- Aachen-Maastricht Institute for Biobased Materials (AMIBM), Faculty of Science and Engineering, Maastricht University, Brightlands Chemelot Campus, Urmonderbaan 22, 6167 RD Geleen, The Netherlands
| | - Stefan Jockenhoevel
- Aachen-Maastricht Institute for Biobased Materials (AMIBM), Faculty of Science and Engineering, Maastricht University, Brightlands Chemelot Campus, Urmonderbaan 22, 6167 RD Geleen, The Netherlands; Department of Biohybrid & Medical Textiles (BioTex), AME-Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Forckenbeckstraβe 55, 52072 Aachen, Germany
| | - Samaneh Ghazanfari
- Aachen-Maastricht Institute for Biobased Materials (AMIBM), Faculty of Science and Engineering, Maastricht University, Brightlands Chemelot Campus, Urmonderbaan 22, 6167 RD Geleen, The Netherlands.
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Tavakoli J, Costi JJ. New insights into the viscoelastic and failure mechanical properties of the elastic fiber network of the inter-lamellar matrix in the annulus fibrosus of the disc. Acta Biomater 2018; 77:292-300. [PMID: 30017922 DOI: 10.1016/j.actbio.2018.07.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/25/2018] [Accepted: 07/10/2018] [Indexed: 10/28/2022]
Abstract
The mechanical role of elastic fibers in the inter-lamellar matrix (ILM) is unknown; however, it has been suggested that they play a role in providing structural integrity to the annulus fibrosus (AF). Therefore, the aim of this study was to measure the viscoelastic and failure properties of the elastic fiber network in the ILM of ovine discs under both tension and shear directions of loading. Utilizing a technique, isolated elastic fibers within the ILM from ovine discs were stretched to 40% of their initial length at three strain rates of 0.1% s-1 (slow), 1% s-1 (medium) and 10% s-1 (fast), followed by a ramp test to failure at 10% s-1. A significant strain-rate dependent response was found, particularly at the fastest rate for phase angle and normalized stiffness (p < 0.001). The elastic fibers in the ILM demonstrated a significantly higher capability for energy absorption at slow compared to medium and fast strain rates (p < 0.001). These finding suggests that the elastic fiber network of the ILM exhibits nonlinear elastic behavior. When tested to failure, a significantly higher normalized failure force was found in tension compared to shear loading (p = 0.011), which is consistent with the orthotropic structure of elastic fibers in the ILM. The results of this study confirmed the mechanical contribution of the elastic fiber network to the ILM and the structural integrity of the AF. This research serves as a foundation for future studies to investigate the relationship between degeneration and ILM mechanical properties. STATEMENT OF SIGNIFICANCE The mechanical role of elastic fibres in the inter-lamellar matrix (ILM) of the disc is unknown. The viscoelastic and failure properties of the elastic fibre network in the ILM in both tension and shear directions of loading was measured for the first time. We found a strain-rate dependent response for the elastic fibres in the ILM. The elastic fibres in the ILM demonstrated a significantly higher capability for energy absorption at slow compared to medium and fast strain rates. When tested to failure, a significantly higher normalized failure force was found in tension compared to shear loading, which is consistent with the orthotropic structure of elastic fibres in the ILM.
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Ultrastructural organization of elastic fibres in the partition boundaries of the annulus fibrosus within the intervertebral disc. Acta Biomater 2018; 68:67-77. [PMID: 29269332 DOI: 10.1016/j.actbio.2017.12.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 12/14/2017] [Accepted: 12/14/2017] [Indexed: 11/21/2022]
Abstract
The relationship between elastic fibre disorders and disc degeneration, aging and progression of spine deformity have been discussed in a small number of studies. However, the clinical relevance of elastic fibres in the annulus fibrosus (AF) of the disc is poorly understood. Ultrastructural visualization of elastic fibres is an important step towards understanding their structure-function relationship. In our previous studies, a novel technique for visualization of elastic fibres across the AF was presented and their ultrastructural organization in intra- and inter-lamellar regions was compared. Using the same novel technique in the present study, the ultrastructural organization of elastic fibres in the partition boundaries (PBs), which are located between adjacent collagen bundles, is presented for the first time. Visualization of elastic fibres in the PBs in control and partially digested (digested) samples was compared, and their orientation in two different cutting planes (transverse and oblique) were discussed. The ultrastructural analysis revealed that elastic fibres in PBs were a well-organized dense and complex network having different size and shape. Adjacent collagen bundles in a cross section (CS) lamella appear to be connected to each other, where elastic fibres in the PBs were merged in parallel or penetrated into the collagen bundles. There was no significant difference in directional coherency coefficient of elastic fibres between the two different cutting planes (p = .35). The present study revealed that a continuous network of elastic fibres may provide disc integrity by connecting adjacent bundles of CS lamellae together. Compared to our previous studies, the density of the elastic fibre network in PBs was lower, and fibre orientation was similar to the intra-lamellar space and inter-lamellar matrix. STATEMENT OF SIGNIFICANCE A detailed ultrastructural study in the partition boundaries of the annulus fibrosus within the disc revealed a well-organized elastic fibre network with a complex ultrastructure. The continuous network of elastic fibres may provide disc integrity by connecting adjacent bundles of cross section lamellae together. The density of the elastic fibre network in PBs was lower, and fibre orientation was similar to the intra-lamellar space and the inter-lamellar matrix.
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Tavakoli J, Elliott DM, Costi JJ. The ultra-structural organization of the elastic network in the intra- and inter-lamellar matrix of the intervertebral disc. Acta Biomater 2017; 58:269-277. [PMID: 28526629 DOI: 10.1016/j.actbio.2017.05.036] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 05/01/2017] [Accepted: 05/15/2017] [Indexed: 11/18/2022]
Abstract
The inter-lamellar matrix (ILM)-located between adjacent lamellae of the annulus fibrosus-consists of a complex structure of elastic fibers, while elastic fibers of the intra-lamellar region are aligned predominantly parallel to the collagen fibers. The organization of elastic fibers under low magnification, in both inter- and intra-lamellar regions, was studied by light microscopic analysis of histologically prepared samples; however, little is known about their ultrastructure. An ultrastructural visualization of elastic fibers in the inter-lamellar matrix is crucial for describing their contribution to structural integrity, as well as mechanical properties of the annulus fibrosus. The aims of this study were twofold: first, to present an ultrastructural analysis of the elastic fiber network in the ILM and intra-lamellar region, including cross section (CS) and in-plane (IP) lamellae, of the AF using Scanning Electron Microscopy (SEM) and second, to -compare the elastic fiber orientation between the ILM and intra-lamellar region. Four samples (lumbar sheep discs) from adjacent sections (30μm thickness) of anterior annulus were partially digested by a developed NaOH-sonication method for visualization of elastic fibers by SEM. Elastic fiber orientation and distribution were quantified relative to the tangential to circumferential reference axis. Visualization of the ILM under high magnification revealed a dense network of elastic fibers that has not been previously described. Within the ILM, elastic fibers form a complex network, consisting of different size and shape fibers, which differed to those located in the intra-lamellar region. For both regions, the majority of fibers were oriented near 0° with respect to tangential to circumferential (TCD) direction and two minor symmetrical orientations of approximately±45°. Statistically, the orientation of elastic fibers between the ILM and intra-lamellar region was not different (p=0.171). The present study used extracellular matrix partial digestion to address significant gaps in understanding of disc microstructure and will contribute to multidisciplinary ultrastructure-function studies. STATEMENT OF SIGNIFICANCE Visualization of the intra-lamellar matrix under high magnification revealed a dense network of elastic fibers that has not been previously described. The present study used extracellular matrix partial digestion to address significant gaps in understanding of disc microstructure and will contribute to multidisciplinary ultrastructure-function studies.
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Affiliation(s)
- J Tavakoli
- Biomechanics and Implants Research Group, The Medical Device Research Institute, School of Computer Science, Engineering and Mathematics, Flinders University, GPO Box 2100, Adelaide, South Australia 5001, Australia
| | - D M Elliott
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
| | - J J Costi
- Biomechanics and Implants Research Group, The Medical Device Research Institute, School of Computer Science, Engineering and Mathematics, Flinders University, GPO Box 2100, Adelaide, South Australia 5001, Australia.
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15
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Newell N, Little JP, Christou A, Adams MA, Adam CJ, Masouros SD. Biomechanics of the human intervertebral disc: A review of testing techniques and results. J Mech Behav Biomed Mater 2017; 69:420-434. [PMID: 28262607 DOI: 10.1016/j.jmbbm.2017.01.037] [Citation(s) in RCA: 185] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 01/06/2017] [Accepted: 01/23/2017] [Indexed: 01/08/2023]
Abstract
Many experimental testing techniques have been adopted in order to provide an understanding of the biomechanics of the human intervertebral disc (IVD). The aim of this review article is to amalgamate results from these studies to provide readers with an overview of the studies conducted and their contribution to our current understanding of the biomechanics and function of the IVD. The overview is presented in a way that should prove useful to experimentalists and computational modellers. Mechanical properties of whole IVDs can be assessed conveniently by testing 'motion segments' comprising two vertebrae and the intervening IVD and ligaments. Neural arches should be removed if load-sharing between them and the disc is of no interest, and specimens containing more than two vertebrae are required to study 'adjacent level' effects. Mechanisms of injury (including endplate fracture and disc herniation) have been studied by applying complex loading at physiologically-relevant loading rates, whereas mechanical evaluations of surgical prostheses require slower application of standardised loading protocols. Results can be strongly influenced by the testing environment, preconditioning, loading rate, specimen age and degeneration, and spinal level. Component tissues of the disc (anulus fibrosus, nucleus pulposus, and cartilage endplates) have been studied to determine their material properties, but only the anulus has been thoroughly evaluated. Animal discs can be used as a model of human discs where uniform non-degenerate specimens are required, although differences in scale, age, and anatomy can lead to problems in interpretation.
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Affiliation(s)
- N Newell
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom.
| | - J P Little
- Paediatric Spine Research Group, IHBI at Centre for Children's Health Research, Queensland University of Technology, Brisbane, Australia
| | - A Christou
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - M A Adams
- Centre for Applied Anatomy, University of Bristol, Southwell Street, Bristol BS2 8EJ, United Kingdom
| | - C J Adam
- Paediatric Spine Research Group, IHBI at Centre for Children's Health Research, Queensland University of Technology, Brisbane, Australia
| | - S D Masouros
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
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Sato N, Taniguchi T, Goda Y, Kosaka H, Higashino K, Sakai T, Katoh S, Yasui N, Sairyo K, Taniguchi H. Proteomic Analysis of Human Tendon and Ligament: Solubilization and Analysis of Insoluble Extracellular Matrix in Connective Tissues. J Proteome Res 2016; 15:4709-4721. [DOI: 10.1021/acs.jproteome.6b00806] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Nori Sato
- Department
of Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Takako Taniguchi
- Division
of Disease Proteomics, Institute for Enzyme Research, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Yuichiro Goda
- Department
of Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Hirofumi Kosaka
- Department
of Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Kosaku Higashino
- Department
of Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Toshinori Sakai
- Department
of Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Shinsuke Katoh
- Department
of Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Natsuo Yasui
- Department
of Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Koichi Sairyo
- Department
of Orthopedics, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Hisaaki Taniguchi
- Division
of Disease Proteomics, Institute for Enzyme Research, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
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17
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Tavakoli J, Elliott DM, Costi JJ. Structure and mechanical function of the inter-lamellar matrix of the annulus fibrosus in the disc. J Orthop Res 2016; 34:1307-15. [PMID: 27208689 DOI: 10.1002/jor.23306] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 05/11/2016] [Indexed: 02/04/2023]
Abstract
The inter-lamellar matrix (ILM) has an average thickness of less than 30 µm and lies between adjacent lamellae in the annulus fibrosus (AF). The microstructure and composition of the ILM have been studied in various anatomic regions of the disc; however, their contribution to AF mechanical properties and structural integrity is unknown. It was suggested that the ILM components, mainly elastic fibers and cross-bridges, play a role in providing mechanical integrity of the AF. Therefore, the manner in which they respond to different loadings and stabilize adjacent lamellae structure will influence AF tear formation and subsequent herniation. This review paper summarizes the composition, microstructure, and potential role of the ILM in the progression of disc herniation, clarifies the micromechanical properties of the ILM, and proposes critical areas for future studies. There are a number of unknown characteristics of the ILM, such as its mechanical role, impact on AF integrity, and ultrastructure of elastic fibers at the ILM-lamella boundary. Determining these characteristics will provide important information for tissue engineering, repair strategies, and the development of more-physiological computational models to study the initiation and propagation of AF tears that lead to herniation and degeneration. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1307-1315, 2016.
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Affiliation(s)
- Javad Tavakoli
- Biomechanics and Implants Research Group, The Medical Device Research Institute, School of Computer Science, Engineering and Mathematics, Flinders University, GPO Box 2100, Adelaide 5042, South Australia, Australia
| | - Dawn M Elliott
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware
| | - John J Costi
- Biomechanics and Implants Research Group, The Medical Device Research Institute, School of Computer Science, Engineering and Mathematics, Flinders University, GPO Box 2100, Adelaide 5042, South Australia, Australia
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18
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Bezci SE, Nandy A, O'Connell GD. Effect of Hydration on Healthy Intervertebral Disk Mechanical Stiffness. J Biomech Eng 2016; 137:101007. [PMID: 26300418 DOI: 10.1115/1.4031416] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Indexed: 11/08/2022]
Abstract
The intervertebral disk has an excellent swelling capacity to absorb water, which is thought to be largely due to the high proteoglycan composition. Injury, aging, degeneration, and diurnal loading are all noted by a significant decrease in water content and tissue hydration. The objective of this study was to evaluate the effect of hydration, through osmotic loading, on tissue swelling and compressive stiffness of healthy intervertebral disks. The wet weight of nucleus pulposus (NP) and annulus fibrosus (AF) explants following swelling was 50% or greater, demonstrating significant ability to absorb water under all osmotic loading conditions (0.015 M-3.0 M phosphate buffered saline (PBS)). Estimated NP residual strains, calculated from the swelling ratio, were approximately 1.5 × greater than AF residual strains. Compressive stiffness increased with hyperosmotic loading, which is thought to be due to material compaction from osmotic-loading and the nonlinear mechanical behavior. Importantly, this study demonstrated that residual strains and material properties are greatly dependent on osmotic loading. The findings of this study support the notion that swelling properties from osmotic loading will be important for accurately describing the effect of degeneration and injury on disk mechanics. Furthermore, the tissue swelling will be an important consideration for developing biological repair strategies aimed at restoring mechanical behavior toward a healthy disk.
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Kobielarz M, Szotek S, Głowacki M, Dawidowicz J, Pezowicz C. Qualitative and quantitative assessment of collagen and elastin in annulus fibrosus of the physiologic and scoliotic intervertebral discs. J Mech Behav Biomed Mater 2016; 62:45-56. [PMID: 27177214 DOI: 10.1016/j.jmbbm.2016.04.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 04/15/2016] [Accepted: 04/25/2016] [Indexed: 02/02/2023]
Abstract
The biophysical properties of the annulus fibrosus of the intervertebral disc are determined by collagen and elastin fibres. The progression of scoliosis is accompanied by a number of pathological changes concerning these structural proteins. This is a major cause of dysfunction of the intervertebral disc. The object of the study were annulus fibrosus samples excised from intervertebral discs of healthy subjects and patients treated surgically for scoliosis in the thoracolumbar or lumbar spine. The research material was subjected to structural analysis by light microscopy and quantitative analysis of the content of collagen types I, II, III and IV as well as elastin by immunoenzymatic test (ELISA). A statistical analysis was conducted to assess the impact of the sampling site (Mann-Whitney test, α=0.05) and scoliosis (Wilcoxon matched pairs test, α=0.05) on the obtained results. The microscopic studies conducted on scoliotic annulus fibrosus showed a significant architectural distortion of collagen and elastin fibres. Quantitative biochemical assays demonstrated region-dependent distribution of only collagen types I and II in the case of healthy intervertebral discs whereas in the case of scoliotic discs region-dependent distribution concerned all examined proteins of the extracellular matrix. Comparison of scoliotic and healthy annulus fibrosus revealed a significant decrease in the content of collagen type I and elastin as well as a slight increase in the proportion of collagen types III and IV. The content of collagen type II did not differ significantly between both groups. The observed anomalies are a manifestation of degenerative changes affecting annulus fibrosus of the intervertebral disc in patients suffering from scoliosis.
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Affiliation(s)
- Magdalena Kobielarz
- Department of Biomedical Engineering, Mechatronics and Theory of Mechanisms, Wroclaw University of Technology, Łukasiewicza 7/9, 50-371 Wroclaw, Poland
| | - Sylwia Szotek
- Department of Biomedical Engineering, Mechatronics and Theory of Mechanisms, Wroclaw University of Technology, Łukasiewicza 7/9, 50-371 Wroclaw, Poland.
| | - Maciej Głowacki
- Department of Paediatric Orthopaedics, Karol Marcinkowski University of Medical Sciences, 28 Czerwca 1956r., 61-545 Poznan, Poland
| | | | - Celina Pezowicz
- Department of Biomedical Engineering, Mechatronics and Theory of Mechanisms, Wroclaw University of Technology, Łukasiewicza 7/9, 50-371 Wroclaw, Poland
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20
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Role of biomolecules on annulus fibrosus micromechanics: effect of enzymatic digestion on elastic and failure properties. J Mech Behav Biomed Mater 2014; 40:75-84. [PMID: 25212387 DOI: 10.1016/j.jmbbm.2014.08.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 08/07/2014] [Accepted: 08/12/2014] [Indexed: 01/07/2023]
Abstract
Uniaxial tension was applied to selectively digested single lamellar human cadaveric annulus fibrosus specimens to investigate the role of different biomolecules in annular biomechanics. Single layered and inter-lamellar annulus fibrosus samples were obtained from 10 isolated cadaveric lumbar intervertebral discs in one of four orientations: longitudinal, transverse, radial, and circumferential. Within each orientation the samples were subjected to a selective enzymatic digestion protocol with collagenase, elastase, chondroitinase ABC, or 1× Phosphate Buffered Saline. Uniaxial tensile tests were performed to failure at a strain rate of 0.005s(-1). Failure stress and strain, and elastic moduli were compared among the digested conditions. The collagenase- and elastase-treated groups had the most significant effect on the mechanical properties among the orientation groups, decreasing the failure stress for both interlaminar and intralaminar groups. Collagenase-treated groups showed an increase in the failure strain following enzymatic digestion for the intralaminar groups and one interlaminar testing direction (circumferential). The chondroitinase ABC-treated group only had a significant impact on the single layer orientations, decreasing the failure stress and strain (intralaminar group). The digested properties described provide insights into the laminar mechanical behavior and the role of the molecular components to the annular mechanical behavior. Understanding annular mechanics may prove insightful in diagnosis, prevention and repair of debilitating intervertebral disc disorders and manufacturing of tissue-engineered annulus.
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Henninger HB, Underwood CJ, Romney SJ, Davis GL, Weiss JA. Effect of elastin digestion on the quasi-static tensile response of medial collateral ligament. J Orthop Res 2013; 31:1226-33. [PMID: 23553827 PMCID: PMC4112956 DOI: 10.1002/jor.22352] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 02/22/2013] [Indexed: 02/04/2023]
Abstract
Elastin is a structural protein that provides resilience to biological tissues. We examined the contributions of elastin to the quasi-static tensile response of porcine medial collateral ligament through targeted disruption of the elastin network with pancreatic elastase. Elastase concentration and treatment time were varied to determine a dose response. Whereas elastin content decreased with increasing elastase concentration and treatment time, the change in peak stress after cyclic loading reached a plateau above 1 U/ml elastase and 6 h treatment. For specimens treated with 2 U/ml elastase for 6 h, elastin content decreased approximately 35%. Mean peak tissue strain after cyclic loading (4.8%, p ≥ 0.300), modulus (275 MPa, p ≥ 0.114) and hysteresis (20%, p ≥ 0.553) were unaffected by elastase digestion, but stress decreased significantly after treatment (up to 2 MPa, p ≤ 0.049). Elastin degradation had no effect on failure properties, but tissue lengthened under the same pre-stress. Stiffness in the linear region was unaffected by elastase digestion, suggesting that enzyme treatment did not disrupt collagen. These results demonstrate that elastin primarily functions in the toe region of the stress-strain curve, yet contributes load support in the linear region. The increase in length after elastase digestion suggests that elastin may pre-stress and stabilize collagen crimp in ligaments.
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Affiliation(s)
- Heath B. Henninger
- Department of Bioengineering, and Scientific Computing and Imaging Institute, University of Utah,Department of Orthopaedics, University of Utah
| | - Clayton J. Underwood
- Department of Bioengineering, and Scientific Computing and Imaging Institute, University of Utah
| | | | - Grant L. Davis
- Department of Bioengineering, and Scientific Computing and Imaging Institute, University of Utah
| | - Jeffrey A. Weiss
- Department of Bioengineering, and Scientific Computing and Imaging Institute, University of Utah,Department of Orthopaedics, University of Utah
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22
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Hayes AJ, Smith SM, Melrose J. Comparative immunolocalisation of fibrillin-1 and perlecan in the human foetal, and HS-deficient hspg2 exon 3 null mutant mouse intervertebral disc. Histochem Cell Biol 2012; 139:1-11. [PMID: 23104139 DOI: 10.1007/s00418-012-1041-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2012] [Indexed: 12/20/2022]
Abstract
The aim of this study was to examine the comparative localisations of fibrillin-1 and perlecan in the foetal human, wild-type C57BL/6 and HS-deficient hspg2Δ³⁻/Δ³⁻ exon 3 null mouse intervertebral disc (IVD) using fluorescent laser scanning confocal microscopy. Fibrillin-1 fibrils were prominent components of the outer posterior and anterior annulus fibrosus (AF) of the foetal human IVD. Finer fibrillin-1 fibrils were evident in the inner AF where they displayed an arcade-type arrangement in the developing lamellae. Relatively short but distinct fibrillin-1 fibrils were evident in the central region of the IVD and presumptive cartilaginous endplate and defined the margins of the nuclear sheath in the developing nucleus pulposus (NP). Fibrillin-1 was also demonstrated in the AF of C57BL/6 wild-type mice but to a far lesser extent in the HS-deficient hspg2Δ³⁻/Δ³⁻ exon 3 null mouse. This suggested that the HS chains of perlecan may have contributed to fibrillin-1 assembly or its deposition in the IVD. The cell-matrix interconnections provided by the fibrillin fibrils visualised in this study may facilitate communication between disc cells and their local biomechanical microenvironment in mechanosensory processes which regulate tissue homeostasis. The ability of fibrillin-1 to sequester TGF-β a well-known anabolic growth factor in the IVD also suggests potential roles in disc development and/or remodelling.
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Affiliation(s)
- Anthony J Hayes
- Confocal Microscopy Unit, Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3US, Wales, UK
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23
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Sivan SS, Van El B, Merkher Y, Schmelzer CEH, Zuurmond AM, Heinz A, Wachtel E, Varga PP, Lazary A, Brayda-Bruno M, Maroudas A. Longevity of elastin in human intervertebral disc as probed by the racemization of aspartic acid. Biochim Biophys Acta Gen Subj 2012; 1820:1671-7. [PMID: 22728886 DOI: 10.1016/j.bbagen.2012.06.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 04/30/2012] [Accepted: 06/15/2012] [Indexed: 11/19/2022]
Abstract
BACKGROUND Aging and degeneration of human intervertebral disc (IVD) are associated with biochemical changes, including racemization and glycation. These changes can only be counteracted by protein turnover. Little is known about the longevity of IVD elastin in health or disease. Yet, such knowledge is important for a quantitative understanding of tissue synthesis and degradation. METHODS We have measured the accumulation of d-Asp and pentosidine in IVD elastin. Samples representing a broad range of ages (28-82years) and degeneration grades (1-5) were analyzed. RESULTS d/l-Asp for elastin increased linearly with age from 3.2% (early 30s) to 14.8% (early 80s) for normal tissue (grades 1-2) and from 1.7% (late 20s) to 6.0% (until the mid 50s) for degenerate tissue (grades 3-5) with accumulation rates of 16.2±3.1×10(-4) and 11.7±3.8×10(-4)year(-1), respectively; no significant difference was found between these values (p<0.05). Above the mid 50s, a decrease in d-Asp accumulation was recorded in the degenerate tissue. d-Asp accumulation correlated well with pentosidine content for elastin from healthy and degenerate tissues combined. We conclude that IVD elastin is metabolically-stable and long-lived in both healthy and degenerate human IVDs, with signs of new synthesis in the latter. The correlation of d-Asp with pentosidine content suggests that both these agents may be used as markers in the overall aging process of IVD. GENERAL SIGNIFICANCE Accumulation of modified IVD elastin argues for its longevity and may have a negative impact on its role in disc function. Weak signs of newly synthesized molecules may act to counteract this effect in degenerate tissue.
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Affiliation(s)
- Sarit-Sara Sivan
- Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel.
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Srokowski EM, Woodhouse KA. Development and characterisation of novel cross-linked bio-elastomeric materials. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2012; 19:785-99. [DOI: 10.1163/156856208784522038] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Elizabeth M. Srokowski
- a Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, RM 363, Toronto, ON, Canada M5S 3E5
| | - Kimberly A. Woodhouse
- b Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, RM 363, Toronto, ON, Canada M5S 3E5; Advanced Regenerative Tissue Engineering Centre, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, Canada M4N 3M5
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Comparative immunolocalization of the elastin fiber-associated proteins fibrillin-1, LTBP-2, and MAGP-1 with components of the collagenous and proteoglycan matrix of the fetal human intervertebral disc. Spine (Phila Pa 1976) 2011; 36:E1365-72. [PMID: 21540769 DOI: 10.1097/brs.0b013e31821fd23e] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN A comparative immunolocalization study of elastin-associated proteins and established intervertebral disc (IVD) extracellular matrix (ECM) components. OBJECTIVE To localize for the first time, elastic fiber–associated proteins with structural fibrillar components in the annulus fibrosus (AF) of the fetal IVD. SUMMARY OF BACKGROUND DATA Elastin has been identified histochemically in adult bovine, human, and immature rat IVDs, and in fetal human IVDs using electron microscopy; however, no immunolocalization studies have been undertaken for associated components in human fetal IVDs. METHODS En-bloc fixation of thoracolumbar spinal segments in formalin and Histochoice followed by standard histochemical processing, paraffin embedding, microtome sectioning, and identification of IVD ECM components using a range of specific mono- and polyclonal antibodies and bright-field and laser scanning confocal microscopy. RESULTS The elastic fiber-associated proteins fibrillin-1, LTBP-2, and MAGP-1 were prominently immunolocalized in the outer lamellar layers of the AF of the human fetal IVD. Dual localization of selected components by confocal microscopy demonstrated that versican and LTBP-2 were colocalized with fibrillin-1 microfibrils in the AF lamellae with a similar distribution to the elastin fibers. LTBP-2 was also associated with pericellular perlecan in the outer AF. These interconnections between elastin-associated proteins resulted in an elastic network, which connected the AF cells with the adjacent cartilaginous vertebral bodies. CONCLUSION Specific immunolocalization of fibrillin-1, MAGP-1, and versican with elastin in the outer AF of the fetal human IVD has been demonstrated. We deduce from the established distributions of the elastin-associated proteins and their known interactivities with matrix components that these stabilize and aid in the integration of the elastic fibers in the annular lamellae and may be responsible for the generation of tensional forces in the outer AF, which direct the assembly of this tissue.
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Kuo CK, Marturano JE, Tuan RS. Novel strategies in tendon and ligament tissue engineering: Advanced biomaterials and regeneration motifs. BMC Sports Sci Med Rehabil 2010; 2:20. [PMID: 20727171 PMCID: PMC2939640 DOI: 10.1186/1758-2555-2-20] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Accepted: 08/20/2010] [Indexed: 02/08/2023]
Abstract
Tendon and ligaments have poor healing capacity and when injured often require surgical intervention. Tissue replacement via autografts and allografts are non-ideal strategies that can lead to future problems. As an alternative, scaffold-based tissue engineering strategies are being pursued. In this review, we describe design considerations and major recent advancements of scaffolds for tendon/ligament engineering. Specifically, we outline native tendon/ligament characteristics critical for design parameters and outcome measures, and introduce synthetic and naturally-derived biomaterials used in tendon/ligament scaffolds. We will describe applications of these biomaterials in advanced tendon/ligament engineering strategies including the utility of scaffold functionalization, cyclic strain, growth factors, and interface considerations. The goal of this review is to compile and interpret the important findings of recent tendon/ligament engineering research in an effort towards the advancement of regenerative strategies.
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Affiliation(s)
- Catherine K Kuo
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - Joseph E Marturano
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - Rocky S Tuan
- Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
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Synthesis of highly porous crosslinked elastin hydrogels and their interaction with fibroblasts in vitro. Biomaterials 2009; 30:4550-7. [DOI: 10.1016/j.biomaterials.2009.05.014] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Accepted: 05/10/2009] [Indexed: 11/22/2022]
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Michalek AJ, Buckley MR, Bonassar LJ, Cohen I, Iatridis JC. Measurement of local strains in intervertebral disc anulus fibrosus tissue under dynamic shear: contributions of matrix fiber orientation and elastin content. J Biomech 2009; 42:2279-85. [PMID: 19664773 DOI: 10.1016/j.jbiomech.2009.06.047] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Revised: 06/15/2009] [Accepted: 06/17/2009] [Indexed: 11/26/2022]
Abstract
Shear strain has been implicated as an initiator of intervertebral disc anulus failure, however a clear, multi-scale picture of how shear strain affects the tissue microstructure has been lacking. The purposes of this study were to measure microscale deformations in anulus tissue under dynamic shear in two orientations, and to determine the role of elastin in regulating these deformations. Bovine AF tissue was simultaneously shear loaded and imaged using confocal microscopy following either a buffer or elastase treatment. Digital image analysis was used to track through time local shear strains in specimens sheared transversely, and stretch and rotation of collagen fiber bundles in specimens sheared circumferentially. The results of this study suggest that sliding does not occur between AF plies under shear, and that interlamellar connections are governed by collagen and fibrilin rather than elastin. The transverse shear modulus was found to be approximately 1.6 times as high in plies the direction of the collagen fibers as in plies across them. Under physiological levels of in-plane shear, fiber bundles stretched and re-oriented linearly. Elastin was found to primarily stiffen plies transversely. We conclude that alterations in the elastic fiber network, as found with IVD herniation and degeneration, can therefore be expected to significantly influence the AF response to shear making it more susceptible to micro failure under bending or torsion loading.
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Affiliation(s)
- Arthur J Michalek
- College of Engineering and Mathematical Sciences, University of Vermont, 201 Perkins Building, 23 Colchester Ave, Burlington, VT 05405, USA
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Daum O, Ferda J, Curik R, Choc M, Mukensnabl P, Michal M. Elastofibromatous Changes in Tissues From Spinal Biopsies. A Degenerative Process Afflicting a Small but Important Subset Of Patients Operated for Spinal Canal Compression: Report of 18 Cases. Int J Surg Pathol 2009; 18:508-15. [DOI: 10.1177/1066896909339736] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Elastofibroma is a tumorlike lesion occurring usually in the subscapular region of elderly females. In this study, 18 cases of elastofibromatous tissue retrieved from the spinal canal were analyzed to elucidate its frequency and possible clinical associations. The patients included 8 men and 10 women with a mean age of 63.4 years (range, 40-84 years). The elastic nature of the material was confirmed by Weigert’s elastic stain and immunohistochemically. Elastofibroma was diagnosed in 6 patients, and elastofibroma-like tissue was found in 11 samples. The finding of elastofibromatous tissue was associated with clinical diagnosis of juxtaarticular cysts (3 cases), thickening of ligamentum flavum (4 cases), extradural expansion (2 cases), metastatic involvement of the dorsal spine (3 cases), and a vertebral fracture (1 case). Two cases were located above the transpedicular fixation. Elastofibromatous tissue may be found in approximately 2.6% of all spinal biopsies and it may take part in compression of spinal cord and nerve roots.
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Affiliation(s)
- Ondrej Daum
- Departments of Pathology, Medical Faculty Hospital, Charles University in Prague
| | - Jiri Ferda
- Radiology, Medical Faculty Hospital, Charles University in Prague
| | - Romuald Curik
- Medical Faculty in Plzen; Biopticka Laborator s.r.o (RC), Plzen, Czech Republic
| | - Milan Choc
- Neurosurgery (MC), Medical Faculty Hospital, Charles University in Prague
| | - Petr Mukensnabl
- Departments of Pathology, Medical Faculty Hospital, Charles University in Prague
| | - Michal Michal
- Departments of Pathology, Medical Faculty Hospital, Charles University in Prague,
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The elastic fibre network of the human lumbar anulus fibrosus: architecture, mechanical function and potential role in the progression of intervertebral disc degeneration. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2009; 18:439-48. [PMID: 19263091 DOI: 10.1007/s00586-009-0918-8] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 12/26/2008] [Accepted: 02/10/2009] [Indexed: 01/09/2023]
Abstract
Elastic fibres are critical constituents of dynamic biological structures that functionally require elasticity and resilience. The network of elastic fibres in the anulus fibrosus of the intervertebral disc is extensive, however until recently, the majority of histological, biochemical and biomechanical studies have focussed on the roles of other extracellular matrix constituents such as collagens and proteoglycans. The resulting lack of detailed descriptions of elastic fibre network architecture and mechanical function has limited understanding of the potentially important contribution made by elastic fibres to healthy disc function and their possible roles in the progression of disc degeneration. In addition, it has made it difficult to postulate what the consequences of elastic fibre related disorders would be for intervertebral disc behaviour, and to develop treatments accordingly. In this paper, we review recent and historical studies which have examined both the structure and the function of the human lumbar anulus fibrosus elastic fibre network, provide a synergistic discussion in an attempt to clarify its potentially critical contribution both to normal intervertebral disc behaviour and the processes relating to its degeneration, and recommend critical areas for future research.
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Sivan SS, Wachtel E, Tsitron E, Sakkee N, van der Ham F, Degroot J, Roberts S, Maroudas A. Collagen turnover in normal and degenerate human intervertebral discs as determined by the racemization of aspartic acid. J Biol Chem 2008; 283:8796-801. [PMID: 18250164 DOI: 10.1074/jbc.m709885200] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Knowledge of rates of protein turnover is important for a quantitative understanding of tissue synthesis and catabolism. In this work, we have used the racemization of aspartic acid as a marker for the turnover of collagen obtained from healthy and pathological human intervertebral disc matrices. We measured the ratio of the d- and l-isomers in collagen extracted from these tissues as a function of age between 16 and 77 years. For collagen taken from healthy discs, the fractional increase of d-Asp was found to be 6.74 x 10(-4)/year; for degenerate discs, the corresponding rate was 5.18 x 10(-4)/year. Using the racemization rate found previously for the stable population of collagen molecules in dentin, we found that the rate of collagen turnover (k(T)) in discs is not constant but rather a decreasing function of age. The average turnover rate in normal disc between the ages of 20 and 40 is 0.00728 +/- 0.00275/year, and that between the ages of 50 and 80 is 0.00323 +/- 0.000947/year, which correspond to average half-lives of 95 and 215 years, respectively. Turnover of collagen from degenerate discs may be more rapid than that found for normal discs; however, statistical analysis leaves this point uncertain. The finding of a similar correlation between the accumulation of d-Asp and that of pentosidine for three normal collagenous tissues further supports the idea that the accumulation of pentosidine in a particular tissue can, along with the racemization of aspartic acid, be used as a reliable measure of protein turnover.
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Affiliation(s)
- Sarit-Sara Sivan
- Department of Biomedical Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
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32
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Cloyd JM, Elliott DM. Elastin content correlates with human disc degeneration in the anulus fibrosus and nucleus pulposus. Spine (Phila Pa 1976) 2007; 32:1826-31. [PMID: 17762289 DOI: 10.1097/brs.0b013e3181132a9d] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Quantitative study of elastin content in nondegenerate and degenerate human intervertebral discs. OBJECTIVE To measure the site-specific changes in elastin content that accompany disc degeneration using a quantitative, dye-binding assay to assess elastin levels. SUMMARY OF BACKGROUND DATA Recently, an abundant and organized network of elastic fibers was observed in nondegenerated human disc using immunostaining histochemistry, suggesting a functional role for elastin. While degenerative changes in the disc extracellular matrix composition are well known, changes in elastin content that may accompany degeneration have not been reported. METHODS Human discs were assigned a degenerative grade by 3 independent orthopedic surgeons based on gross morphology. Samples were taken from the outer anulus fibrosus (OAF), inner AF (IAF) and nucleus pulposus (NP). Elastin content was measured using a specific, dye-binding assay and normalized to dry weight and collagen content, which was measured via a hydroxyproline assay. Samples were divided into 2 groups: nondegenerate (Grades 1-2.5) and degenerate (Grades 2.6-4.0). A 2-way analysis of variance was used to test for statistical significance where the 2 factors were disc location and degeneration. Correlations of composition with degeneration and age were analyzed. RESULTS In nondegenerate tissue, elastin by dry weight was on average 2.0% +/- 0.3%, and there were no differences in elastin content among the locations of OAF, IAF, or NP. With degeneration, there was a significant increase in total disc elastin per dry weight at each location. The degenerate IAF had the largest amount of elastin (9.3% +/- 2.3%), significantly greater than the NP and OAF. Elastin content correlated with degenerative grade and age at each site. CONCLUSION Based on the location-dependent degenerative changes, with highest increases in the IAF, elastin may function to restore lamellar structure under radial loads that potentially cause delamination. Future work will focus on distinguishing the changes in elastin orientation with degeneration and understanding the mechanical functional role of elastin in the disc.
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Affiliation(s)
- Jordan M Cloyd
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104-6081, USA
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Guerin HL, Elliott DM. Quantifying the contributions of structure to annulus fibrosus mechanical function using a nonlinear, anisotropic, hyperelastic model. J Orthop Res 2007; 25:508-16. [PMID: 17149747 DOI: 10.1002/jor.20324] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The annulus fibrosus of the intervertebral disc is comprised of concentric lamella of oriented collagen fibers embedded in a hydrated proteoglycan matrix with smaller amounts of minor collagens, elastin, and small proteoglycans. Its structure and composition enable the disc to withstand complex loads and result in inhomogeneous, anisotropic, and nonlinear mechanical behaviors. The specific contributions of the annulus fibrosus constituent structures to mechanical function remain unclear. Therefore, the objective of this study was to use a structurally motivated, anisotropic, nonlinear strain energy model of annulus fibrosus to determine the relative contributions of its structural components to tissue mechanical behavior. A nonlinear, orthotropic hyperelastic model was developed for the annulus fibrosus. Terms to describe fibers, matrix, and interactions between annulus fibrosus structures (shear and normal to the fiber directions) were explicitly included. The contributions of these structures were analyzed by including or removing terms and determining the effect on the fit to multidimensional experimental data. Correlation between experimental and model-predicted stress, a Bland-Altman analysis of bias and standard deviation of residuals, and the contribution of structural terms to overall tissue stress were calculated. Both shear and normal interaction terms were necessary to accurately model multidimensional behavior. Inclusion of shear interactions more accurately described annulus fibrosus nonlinearity. Fiber stretch and shear interactions dominated contributions to circumferential direction stress, while normal and shear interactions dominated axial stress. The results suggest that interactions between fibers and matrix, perhaps facilitated by crosslinks, elastin, or minor collagens, augment traditional (i.e., fiber-uncrimping) models of nonlinearity.
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Affiliation(s)
- Heather Lynch Guerin
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Yu J, Fairbank JCT, Roberts S, Urban JPG. The elastic fiber network of the anulus fibrosus of the normal and scoliotic human intervertebral disc. Spine (Phila Pa 1976) 2005; 30:1815-20. [PMID: 16103849 DOI: 10.1097/01.brs.0000173899.97415.5b] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Immunohistochemical study of elastic fibers in human intervertebral discs (IVD) collected at surgery from patients with scoliosis. OBJECTIVES To compare the elastic fiber network in scoliotic discs (idiopathic scoliosis or neuromuscular scoliosis) to that of control (normal) discs. To study whether the change in elastic fiber organization could contribute to the progression of spinal deformity. SUMMARY OF BACKGROUND DATA Elastin and elastic fibers have been identified previously in human IVD but were believed to contribute little to the tissue's mechanical properties. However, a recent immunohistochemical study has revealed an abundant and organized elastic fiber network in bovine IVD, indicating that elastic fibers could play an important mechanical role. This article reports the organization of elastic fibers in human IVD and the changes of elastic fiber organization in scoliosis. METHODS Intact wedges of IVD were obtained from patients undergoing surgery for scoliosis (aged 12-22 years). Control discs were obtained from a patient (aged 12 years) with a spinal tumor and a trauma patient (aged 17 years). The discs were dissected to give radial slices and were snap frozen. Frozen sections were cut and digested with hyaluronidase to remove glycosaminoglycans. Micrographs of the sections were examined by polarized light to visualize collagen organization. The elastic fiber network was visualized immunohistochemically or by histochemical staining with orcein. RESULTS A highly organized elastic fiber network, similar to that described in bovine discs, was revealed in the control human discs. In the anulus fibrosus of control discs, dense elastic fibers were located between adjacent lamellae, with fibers also present within individual lamellae. Elastic fibers appeared to be long (>200 microm) and straight in outer anulus, whereas in inner anulus, they nearly ran parallel to each other and at an angle of approximately 60 degrees or 120 degrees to those in adjacent lamellae. However, in scoliotic discs, elastic fibers were sparse, and the collagen and elastic fiber networks were disorganized with loss of lamellar structure. Cell clusters, one of typical degenerative feature, were seen in scoliotic discs but not in age-matched control discs. CONCLUSIONS Our results reveal an abundant and organized network of elastic fibers in the adolescent (12 and 17-year-olds) human IVD, and suggest that elastic fiber network plays a significant biomechanical role. This network is sparse and disrupted in scoliotic discs, and could be involved in the progression of the spinal deformity.
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Affiliation(s)
- Jing Yu
- University Laboratory of Physiology, Oxford University, Oxford, United Kingdom.
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Nihei A, Hagiwara K, Kikuchi M, Yashiro T, Hoshino Y. Histological investigation of rabbit ligamentum flavum with special reference to differences in spinal levels. Anat Sci Int 2003; 78:162-7. [PMID: 14527130 DOI: 10.1046/j.0022-7722.2003.00050.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The structure of the ligamentum flavum has yet to be fully elucidated and no studies have investigated fine structural differences at different spinal levels in any animals. The aim of the present study was to clarify structural differences in the ligamentum flavum at different spinal levels (cervical: C3/4 and C5/6; upper thoracic: T2/3; lower thoracic: T9/10; lumbar: L3/4) using light and electron microscopy of rabbit specimens. Light microscopy using resorcin-fuchsin staining revealed that the distribution of elastic fibers was diffuse in the cervical and upper thoracic regions, but was generally dense in the lower thoracic and lumbar regions. Electron microscopy demonstrated that the cervical and upper thoracic regions were rich in collagen fibers. Conversely, the lower thoracic and lumbar regions were rich in elastic fibers. Quantitative image analyses displayed thick elastic fibers in the lower thoracic and lumbar regions, with high area ratios. Radiographic examinations revealed that ranges of motion were large at the cervical region, but small at the lower thoracic and lumbar regions. These findings suggest that structure of the ligamentum flavum varies at different spinal levels with respect to differences in motion.
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Affiliation(s)
- Aki Nihei
- Department of Orthopaedic Surgery, Jichi Medical School, Tochigi, Japan.
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Shiraishi Y, Kobayashi M, Yasui M, Ozaki N, Sugiura Y. Innervation and functional characteristics of connective tissues, especially elastic fibers, in human fetal thoracic intervertebral articular capsule and its surroundings. ANATOMY AND EMBRYOLOGY 2003; 206:437-45. [PMID: 12700898 DOI: 10.1007/s00429-003-0320-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/11/2003] [Indexed: 10/20/2022]
Abstract
The articular capsules between the thoracic vertebrae, which have physiologically different functions from those of other levels of the vertebrae, have yet to be subjected to neuro-anatomical and fine structural analysis. In the present study, we analyzed serial frozen sections of decalcified thoracic vertebrae in human fetuses, and identified the articular capsule tissue with its unique distribution of elastic fibers. The fine structure of the elastic fibers was studied by transmission electron microscopy. In the early-stage fetus, the fibrous membrane forming the lateral intervertebral articular capsule contained abundant thin elastic fibers consisting of microfibrils. In the late-stage fetus, the lateral capsule of fibrous membrane was occupied by thick elastic fibers. A medial articular capsule, namely the ligamenta flava, contained numerous thick elastic fibers in both early and late-stage fetuses. The distributional differences in nerve fibers between early and late-stage fetuses were determined by immunostaining, using antibodies raised against protein gene product 9.5 (PGP 9.5; ubiquitin carboxyl-terminal hydrolase). Innervation by PGP 9.5 immunoreactive fibers was limited to the areas of the articular capsules near the blood vessels, which may indicate their functional relation with blood flow. No PGP 9.5 immunoreactive fibers were found in the ligamenta flava of the late-stage fetus. Innervation might be directly involved in the development of the intervertebral articular capsules in normal human fetuses.
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Affiliation(s)
- Yosuke Shiraishi
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya 466-8550, Japan.
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Yu J, Winlove PC, Roberts S, Urban JPG. Elastic fibre organization in the intervertebral discs of the bovine tail. J Anat 2002; 201:465-75. [PMID: 12489758 PMCID: PMC1570996 DOI: 10.1046/j.1469-7580.2002.00111.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Elastic fibres have been revealed by both elastin immunostaining and conventional histological orcein-staining in the intervertebral discs of the bovine tail. These fibres are distributed in all regions of the disc but their organization varies from region to region. In the centre of the nucleus, long (> 150 microm) elastic fibres are orientated radially. In the transitional region between nucleus and annulus, the orientation of the elastic fibres changes, producing a criss-cross pattern. In the annulus itself, elastic fibres appear densely distributed in the region between the lamellae and also in 'bridges' across the lamellae, particularly in the adult. Elastic fibres are apparent within the lamellae, orientated parallel to the collagen fibres of each lamella, particularly in the young (12-day-old) discs. In the region between the disc and the cartilaginous endplate, elastic fibres appear to anchor into the plate and terminate there. The results of this study suggest that elastic fibres contribute to the mechanical functioning of the intervertebral disc. The varying organization of the elastic fibres in the different regions of the disc is likely to relate to the different regional loading patterns.
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Affiliation(s)
- Jing Yu
- Laboratory of Physiology, Oxford University, UK
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Horner HA, Roberts S, Bielby RC, Menage J, Evans H, Urban JPG. Cells from different regions of the intervertebral disc: effect of culture system on matrix expression and cell phenotype. Spine (Phila Pa 1976) 2002; 27:1018-28. [PMID: 12004167 DOI: 10.1097/00007632-200205150-00004] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN This study examined how the culture system and region of cellular origin affect disc cell morphology and extracellular matrix production. OBJECTIVE To determine the role of the cell populations in the different regions of the adult intervertebral disc in maintaining gradients in composition across the disc. SUMMARY OF BACKGROUND DATA It is not known whether the steep profiles in composition across the intervertebral disc are maintained by distinct cell populations or whether differences in cell metabolism are determined by changes in the physical environment across the disc. Very little information exists on the matrix produced by cells from the mature, non-notochordal nucleus pulposus. METHODS Cells were extracted from articular cartilage, nucleus pulposus, and the inner and outer anulus fibrosus of caudal discs from 18- to 24-month-old steers cultured in alginate or collagen gels or in monolayer. The effect of culture system and cell origin on cell morphology and matrix synthesis was measured using 35S-sulphate labeling and indirect immunolocalization. RESULTS Distinct morphologic differences between cells from different regions cultured in monolayer were retained through two passages. The rate of sulfate incorporation varied with cell type. Immediately after isolation, it was two- to threefold greater for nucleus cells than for cells from the disc inner anulus or articular cartilage. The rate was lowest for outer anulus cells. It also varied with culture system. For all cell types, the incorporation rate was highest in alginate and lowest in monolayer. Immunolocalization showed that nucleus cells stained strongly for all proteoglycan epitopes, whereas outer anulus cells stained least and in monolayer produced little proteoglycan. CONCLUSIONS The disc has at least three distinct cell populations, which differ in morphology and in amount and type of matrix they produce. Cells from mature nucleus pulposus produced sulfated glycosaminoglycans at a high rate in contrast to reported results for notochordal nucleus cells. Alginate, although an appropriate culture system for inner anulus and nucleus cells, may not be a suitable medium for outer anulus cells.
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Affiliation(s)
- Heather A Horner
- Physiology Laboratory, Oxford University, Oxford, and the; Centre for Spinal Studies, RJAH Orthopaedic Hospital, Oswestry, Shropshire, United Kingdom
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