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Danyukova T, Alimy AR, Velho RV, Yorgan TA, Di Lorenzo G, von Kroge S, Tidow H, Wiegert JS, Hermans-Borgmeyer I, Schinke T, Rolvien T, Pohl S. Mice heterozygous for an osteogenesis imperfecta-linked MBTPS2 variant display a compromised subchondral osteocyte lacunocanalicular network associated with abnormal articular cartilage. Bone 2023; 177:116927. [PMID: 37797712 DOI: 10.1016/j.bone.2023.116927] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 09/20/2023] [Accepted: 10/02/2023] [Indexed: 10/07/2023]
Abstract
Missense variants in the MBTPS2 gene, located on the X chromosome, have been associated with an X-linked recessive form of osteogenesis imperfecta (X-OI), an inherited bone dysplasia characterized by multiple and recurrent bone fractures, short stature, and various skeletal deformities in affected individuals. The role of site-2 protease, encoded by MBTPS2, and the molecular pathomechanism underlying the disease are to date elusive. This study is the first to report on the generation of two Mbtps2 mouse models, a knock-in mouse carrying one of the disease-causative MBTPS2 variants (N455S) and a Mbtps2 knock-out (ko) mouse. Because both loss-of-function variants lead to embryonic lethality in hemizygous male mutant mice, we performed a comprehensive skeletal analysis of heterozygous Mbtps2+/N455S and Mbtps2+/ko female mice. Both models displayed osteochondral abnormalities such as thinned subchondral bone, altered subchondral osteocyte interconnectivity as well as thickened articular cartilage with chondrocyte clustering, altogether resembling an early osteoarthritis (OA) phenotype. However, distant from the joints, no alterations in the bone mass and turnover could be detected in either of the mutant mice. Based on our findings we conclude that MBTPS2 haploinsufficiency results in early OA-like alterations in the articular cartilage and underlying subchondral bone, which likely precede the development of typical OI phenotype in bone. Our study provides first evidence for a potential role of site-2 protease for maintaining homeostasis of both bone and cartilage.
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Affiliation(s)
- Tatyana Danyukova
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
| | - Assil-Ramin Alimy
- Department of Trauma and Orthopedic Surgery, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
| | - Renata Voltolini Velho
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
| | - Timur A Yorgan
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
| | - Giorgia Di Lorenzo
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
| | - Simon von Kroge
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany; Department of Trauma and Orthopedic Surgery, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
| | - Henning Tidow
- The Hamburg Advanced Research Center for Bioorganic Chemistry (HARBOR), Department of Chemistry, Institute for Biochemistry and Molecular Biology, University of Hamburg, 20146 Hamburg, Germany.
| | - J Simon Wiegert
- Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany.
| | - Irm Hermans-Borgmeyer
- Center for Molecular Neurobiology Hamburg, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
| | - Tim Rolvien
- Department of Trauma and Orthopedic Surgery, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
| | - Sandra Pohl
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
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Dilley KK, Lal A, Nguyen TV, Wong BJF. Second Harmonic Imaging of Nasal, Auricular, and Costal Cartilage. Laryngoscope 2023; 133:3370-3377. [PMID: 37306215 DOI: 10.1002/lary.30803] [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: 01/24/2023] [Accepted: 05/22/2023] [Indexed: 06/13/2023]
Abstract
OBJECTIVE There is little knowledge about the histological organization of facial and costal cartilages in terms of matrix structure and cell morphology. Second harmonic generation (SHG) imaging is a nonlinear imaging technique that capitalizes on signal generation from highly ordered macromolecules such as collagen fibers. The purpose of this study was to use SHG microscopy to image collagen extracellular matrix (ECM) structure, chondrocyte size, and density of these cartilages. STUDY DESIGN Experimental. METHODS Surgical remnants of septal, lower lateral, rib, and auricular cartilages were collected following surgery, sectioned into 0.5-1 mm thick samples and fixed to facilitate batch process imaging. A Leica TCS SP8 MP Microscope and multiphoton laser were used to image the specimens. Images were analyzed for cell size, cell density, and collagen fiber directionality patterns using ImageJ. RESULTS SHG images of septal specimens show mesh-like structure of the ECM. There appears to be a superficial layer, characterized by flattened lacunae and middle zone, marked by circular lacunae clusters, similar to what is observed in articular cartilage. The structure of the ECM depicts a visible orientation perpendicular to the surface of the perichondrium. Cell size and density analysis through ImageJ suggests variety across cartilage types. Directionality analysis indicates that the collagen in the ECM displays preferred direction. CONCLUSION This study establishes clear extracellular models of facial and costal cartilages. Limitations include heterogeneous cartilage thickness due to processing difficulties. Further studies include automating the cutting process to increase uniformity of tissue thickness and increasing sample size to further validate results. LEVEL OF EVIDENCE 2 Laryngoscope, 133:3370-3377, 2023.
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Affiliation(s)
- Katelyn K Dilley
- Beckman Laser Institute and Medical Clinic, Irvine, California, U.S.A
| | - Akarsh Lal
- Beckman Laser Institute and Medical Clinic, Irvine, California, U.S.A
| | - Theodore V Nguyen
- Beckman Laser Institute and Medical Clinic, Irvine, California, U.S.A
| | - Brian J F Wong
- Beckman Laser Institute and Medical Clinic, Irvine, California, U.S.A
- Department of Otolaryngology-Head and Neck Surgery, University of California-Irvine Medical Center, Orange, California, U.S.A
- Department of Biomedical Engineering, Henry Samueli School of Engineering, Irvine, California, U.S.A
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Westermann LM, Fleischhauer L, Vogel J, Jenei-Lanzl Z, Ludwig NF, Schau L, Morellini F, Baranowsky A, Yorgan TA, Di Lorenzo G, Schweizer M, de Souza Pinheiro B, Guarany NR, Sperb-Ludwig F, Visioli F, Oliveira Silva T, Soul J, Hendrickx G, Wiegert JS, Schwartz IVD, Clausen-Schaumann H, Zaucke F, Schinke T, Pohl S, Danyukova T. Imbalanced cellular metabolism compromises cartilage homeostasis and joint function in a mouse model of mucolipidosis type III gamma. Dis Model Mech 2020; 13:dmm046425. [PMID: 33023972 PMCID: PMC7687858 DOI: 10.1242/dmm.046425] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 09/15/2020] [Indexed: 11/23/2022] Open
Abstract
Mucolipidosis type III (MLIII) gamma is a rare inherited lysosomal storage disorder caused by mutations in GNPTG encoding the γ-subunit of GlcNAc-1-phosphotransferase, the key enzyme ensuring proper intracellular location of multiple lysosomal enzymes. Patients with MLIII gamma typically present with osteoarthritis and joint stiffness, suggesting cartilage involvement. Using Gnptg knockout (Gnptgko ) mice as a model of the human disease, we showed that missorting of a number of lysosomal enzymes is associated with intracellular accumulation of chondroitin sulfate in Gnptgko chondrocytes and their impaired differentiation, as well as with altered microstructure of the cartilage extracellular matrix (ECM). We also demonstrated distinct functional and structural properties of the Achilles tendons isolated from Gnptgko and Gnptab knock-in (Gnptabki ) mice, the latter displaying a more severe phenotype resembling mucolipidosis type II (MLII) in humans. Together with comparative analyses of joint mobility in MLII and MLIII patients, these findings provide a basis for better understanding of the molecular reasons leading to joint pathology in these patients. Our data suggest that lack of GlcNAc-1-phosphotransferase activity due to defects in the γ-subunit causes structural changes within the ECM of connective and mechanosensitive tissues, such as cartilage and tendon, and eventually results in functional joint abnormalities typically observed in MLIII gamma patients. This idea was supported by a deficit of the limb motor function in Gnptgko mice challenged on a rotarod under fatigue-associated conditions, suggesting that the impaired motor performance of Gnptgko mice was caused by fatigue and/or pain at the joint.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Lena Marie Westermann
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Lutz Fleischhauer
- Laboratory of Experimental Surgery and Regenerative Medicine, Clinic for General Trauma and Reconstructive Surgery, Ludwig-Maximilians University, 80336 Munich, Germany
- Center for Applied Tissue Engineering and Regenerative Medicine (Canter), University of Applied Sciences, 80533 Munich, Germany
| | - Jonas Vogel
- Center for Applied Tissue Engineering and Regenerative Medicine (Canter), University of Applied Sciences, 80533 Munich, Germany
| | - Zsuzsa Jenei-Lanzl
- Dr. Rolf M. Schwiete Research Unit for Osteoarthritis, Orthopedic University Hospital Friedrichsheim gGmbH, 60528 Frankfurt/Main, Germany
| | - Nataniel Floriano Ludwig
- Post-Graduate Program in Genetics and Molecular Biology, Federal University of Rio Grande do Sul, 90040-060 Porto Alegre, Brazil
| | - Lynn Schau
- RG Behavioral Biology, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Fabio Morellini
- RG Behavioral Biology, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Anke Baranowsky
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Timur A Yorgan
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Giorgia Di Lorenzo
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Michaela Schweizer
- Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Bruna de Souza Pinheiro
- Department of Genetics, Federal University of Rio Grande do Sul, 90040-060 Porto Alegre, Brazil
| | - Nicole Ruas Guarany
- Occupational Therapy Faculty, Federal University of Pelotas, 96010-610 Pelotas, Brazil
| | - Fernanda Sperb-Ludwig
- Department of Genetics, Federal University of Rio Grande do Sul, 90040-060 Porto Alegre, Brazil
| | - Fernanda Visioli
- Pathology Department, Federal University of Rio Grande do Sul, 90040-060 Porto Alegre, Brazil
| | - Thiago Oliveira Silva
- Post-Graduate Program in Medicine: Medical Sciences, Federal University of Rio Grande do Sul, 90040-060 Porto Alegre, Brazil
| | - Jamie Soul
- Skeletal Research Group, Biosciences Institute, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Gretl Hendrickx
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - J Simon Wiegert
- RG Synaptic Wiring and Information Processing, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Ida V D Schwartz
- Department of Genetics, Federal University of Rio Grande do Sul, 90040-060 Porto Alegre, Brazil
- Post-Graduate Program in Medicine: Medical Sciences, Federal University of Rio Grande do Sul, 90040-060 Porto Alegre, Brazil
| | - Hauke Clausen-Schaumann
- Center for Applied Tissue Engineering and Regenerative Medicine (Canter), University of Applied Sciences, 80533 Munich, Germany
| | - Frank Zaucke
- Dr. Rolf M. Schwiete Research Unit for Osteoarthritis, Orthopedic University Hospital Friedrichsheim gGmbH, 60528 Frankfurt/Main, Germany
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Sandra Pohl
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Tatyana Danyukova
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
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Brown ETT, Damen AHA, Thambyah A. The mechanical significance of the zonally differentiated collagen network of articular cartilage in relation to tissue swelling. Clin Biomech (Bristol, Avon) 2020; 79:104926. [PMID: 32008842 DOI: 10.1016/j.clinbiomech.2019.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 09/25/2019] [Accepted: 12/12/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND We hypothesise that the Benninghoff arcade fibril structure motif of cartilage is able to predict the swelling response of cartilage. METHODS A total of ten healthy adult bovine patellae were used for this study, yielding 20 paired full depth cartilage samples (half with surface layer intact and half with surface layer removed). Following excision from the bone, samples were allowed to equilibrate first in physiological saline for 2 h, and then in distilled water for another 2 h to maximise the swelling response. Images were captured using a stereomicroscope to measure strain and the fully-swollen samples were fixed in 10% formalin to retain shape for microscopic and ultrastructural imaging. FINDINGS We expected all swelling samples with an intact 'strain-limiting' surface layer to curl upwards, instead only 70% of them did. For samples without a surface layer, we expected the swelling to be evenly distributed and to remain relatively uncurled; but in 40% of the samples there was a downward curvature (i.e. opposite to that of the previous group). Micro-to-ultrastructural imaging, to determine fibrillar structure and organisation, revealed the deep zone cartilage was an additional counter layer limiting swelling strain, and was the likely cause of the unexpected swelling responses. INTERPRETATION Our expectations that the surface layer alone will influence the swelling response, was based on the assumptions of the Benninghoff arcade model. This study highlights the additional importance of sub-micron scale fibrillar interconnectivity and the role of the deep zone.
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Affiliation(s)
- Emma Te Tūmanako Brown
- Department of Chemical and Materials Engineering, University of Auckland, 2-6 Park Ave, Grafton, Auckland 1023, New Zealand
| | - Alicia Helena Antonetta Damen
- Orthopaedic Biomechanics Group, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, the Netherlands
| | - Ashvin Thambyah
- Department of Chemical and Materials Engineering, University of Auckland, 2-6 Park Ave, Grafton, Auckland 1023, New Zealand.
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Mukherjee S, Nazemi M, Jonkers I, Geris L. Use of Computational Modeling to Study Joint Degeneration: A Review. Front Bioeng Biotechnol 2020; 8:93. [PMID: 32185167 PMCID: PMC7058554 DOI: 10.3389/fbioe.2020.00093] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 01/31/2020] [Indexed: 12/13/2022] Open
Abstract
Osteoarthritis (OA), a degenerative joint disease, is the most common chronic condition of the joints, which cannot be prevented effectively. Computational modeling of joint degradation allows to estimate the patient-specific progression of OA, which can aid clinicians to estimate the most suitable time window for surgical intervention in osteoarthritic patients. This paper gives an overview of the different approaches used to model different aspects of joint degeneration, thereby focusing mostly on the knee joint. The paper starts by discussing how OA affects the different components of the joint and how these are accounted for in the models. Subsequently, it discusses the different modeling approaches that can be used to answer questions related to OA etiology, progression and treatment. These models are ordered based on their underlying assumptions and technologies: musculoskeletal models, Finite Element models, (gene) regulatory models, multiscale models and data-driven models (artificial intelligence/machine learning). Finally, it is concluded that in the future, efforts should be made to integrate the different modeling techniques into a more robust computational framework that should not only be efficient to predict OA progression but also easily allow a patient’s individualized risk assessment as screening tool for use in clinical practice.
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Affiliation(s)
- Satanik Mukherjee
- Prometheus, Division of Skeletal Tissue Engineering, KU Leuven, Leuven, Belgium.,Biomechanics Section, KU Leuven, Leuven, Belgium
| | - Majid Nazemi
- GIGA in silico Medicine, University of Liège, Liège, Belgium
| | - Ilse Jonkers
- Human Movement Biomechanics Research Group, Department of Movement Sciences, KU Leuven, Leuven, Belgium
| | - Liesbet Geris
- Prometheus, Division of Skeletal Tissue Engineering, KU Leuven, Leuven, Belgium.,Biomechanics Section, KU Leuven, Leuven, Belgium.,GIGA in silico Medicine, University of Liège, Liège, Belgium
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6
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García-Couce J, Almirall A, Fuentes G, Kaijzel E, Chan A, Cruz LJ. Targeting Polymeric Nanobiomaterials as a Platform for Cartilage Tissue Engineering. Curr Pharm Des 2019; 25:1915-1932. [DOI: 10.2174/1381612825666190708184745] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 06/26/2019] [Indexed: 01/05/2023]
Abstract
Articular cartilage is a connective tissue structure that is found in anatomical areas that are important for the movement of the human body. Osteoarthritis is the ailment that most often affects the articular cartilage. Due to its poor intrinsic healing capacity, damage to the articular cartilage is highly detrimental and at present the reconstructive options for its repair are limited. Tissue engineering and the science of nanobiomaterials are two lines of research that together can contribute to the restoration of damaged tissue. The science of nanobiomaterials focuses on the development of different nanoscale structures that can be used as carriers of drugs / cells to treat and repair damaged tissues such as articular cartilage. This review article is an overview of the composition of articular cartilage, the causes and treatments of osteoarthritis, with a special emphasis on nanomaterials as carriers of drugs and cells, which reduce inflammation, promote the activation of biochemical factors and ultimately contribute to the total restoration of articular cartilage.
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Affiliation(s)
- Jomarien García-Couce
- Translational Nanobiomaterials and Imaging (TNI) group, Radiology department, Leiden University Medical Centrum, Leiden, Netherlands
| | - Amisel Almirall
- Translational Nanobiomaterials and Imaging (TNI) group, Radiology department, Leiden University Medical Centrum, Leiden, Netherlands
| | - Gastón Fuentes
- Translational Nanobiomaterials and Imaging (TNI) group, Radiology department, Leiden University Medical Centrum, Leiden, Netherlands
| | - Eric Kaijzel
- Translational Nanobiomaterials and Imaging (TNI) group, Radiology department, Leiden University Medical Centrum, Leiden, Netherlands
| | - Alan Chan
- Percuros B.V., Zernikedreef 8, 2333 CL Leiden, Netherlands
| | - Luis J. Cruz
- Translational Nanobiomaterials and Imaging (TNI) group, Radiology department, Leiden University Medical Centrum, Leiden, Netherlands
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Mansfield JC, Mandalia V, Toms A, Winlove CP, Brasselet S. Collagen reorganization in cartilage under strain probed by polarization sensitive second harmonic generation microscopy. J R Soc Interface 2019; 16:20180611. [PMID: 30958161 PMCID: PMC6364654 DOI: 10.1098/rsif.2018.0611] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 12/20/2018] [Indexed: 11/12/2022] Open
Abstract
Type II collagen fibril diameters in cartilage are beneath the diffraction limit of optical microscopy, which makes the assessment of collagen organization very challenging. In this work we use polarization sensitive second harmonic generation (P-SHG) imaging to map collagen organization in articular cartilage, addressing in particular its behaviour under strain and changes which occur in osteoarthritis. P-SHG yields two parameters, molecular order and orientation, which provide measures of the degree of organization both at the molecular scale (below the diffraction limit) and above a few hundred nanometres (at the image pixel size). P-SHG clearly demonstrates the zonal collagen architecture and reveals differences in the structure of the fibrils around chondrocytes. P-SHG also reveals sub-micron scale fibril re-organization in cartilage strips exposed to tensile loading, with an increase in local organization in the superficial zone which weakly correlates with tensile modulus. Finally, P-SHG is used to investigate osteoarthritic cartilage from total knee replacement surgery, and reveals widespread heterogeneity across samples both microscale fibril orientations and their sub-micron organization. By addressing collagen fibril structure on scales intermediate between conventional light and electron microscopy, this study provides new insights into collagen micromechanics and mechanisms of degradation.
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Affiliation(s)
- Jessica C. Mansfield
- Physics, College of Engineering Mathematics and Physical Sciences, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
| | - Vipul Mandalia
- Princess Elizabeth Orthopaedic Centre, Royal Devon and Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK
| | - Andrew Toms
- Princess Elizabeth Orthopaedic Centre, Royal Devon and Exeter Hospital, Barrack Road, Exeter EX2 5DW, UK
| | - C. Peter Winlove
- Physics, College of Engineering Mathematics and Physical Sciences, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
| | - Sophie Brasselet
- Institut Fresnel, CNRS, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
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Richmon JD, Sage AB, Wong VW, Chen AC, Pan C, Sah RL, Watson D. Tensile Biomechanical Properties of Human Nasal Septal Cartilage. ACTA ACUST UNITED AC 2018. [DOI: 10.1177/194589240501900616] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background The biomechanical properties of human septal cartilage have yet to be fully defined and thereby limits our ability to compare tissue-engineered constructs to native tissue. In this study, we analyzed the tensile properties of human nasal septal cartilage with respect to axis of tension, age group, and gender. Methods Fifty-five tensile tests were run on human septal specimens obtained from 28 patients. Samples obtained in the vertical and anterior–posterior (both above and within the maxillary crest) axes were subjected to equilibrium and dynamic tensile testing. Results The average values for strength, failure strain, equilibrium modulus and dynamic modulus were not found to be significantly different with respect to axis of tension testing, age group, or gender. Tensile results for septal cartilage were as follows: equilibrium modulus 3.01 ± 0.39 MPa, dynamic modulus 4.99 ± 0.49 MPa, strength 1.90 ± 0.24 MPa, and failure strain 0.35 ± 0.03 mm/mm. Conclusion We confirm that septal cartilage has weaker tensile properties compared to articular cartilage and found no difference in strength with respect to age, gender, or axis of tension (isotropic).
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Affiliation(s)
- Jeremy D. Richmon
- Division of Otolaryngology–Head and Neck Surgery, University of California, San Diego, California
| | - August B. Sage
- Department of Bioengineering and Whitaker Institute of Biomedical Engineering, University of California, San Diego, California
| | - Van W. Wong
- Department of Bioengineering and Whitaker Institute of Biomedical Engineering, University of California, San Diego, California
| | - Albert C. Chen
- Department of Bioengineering and Whitaker Institute of Biomedical Engineering, University of California, San Diego, California
| | - Christine Pan
- Department of Bioengineering and Whitaker Institute of Biomedical Engineering, University of California, San Diego, California
| | - Robert L. Sah
- Department of Bioengineering and Whitaker Institute of Biomedical Engineering, University of California, San Diego, California
| | - Deborah Watson
- Division of Otolaryngology–Head and Neck Surgery, University of California, San Diego, California
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9
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How a decreased fibrillar interconnectivity influences stiffness and swelling properties during early cartilage degeneration. J Mech Behav Biomed Mater 2017; 75:390-398. [PMID: 28803113 DOI: 10.1016/j.jmbbm.2017.07.042] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 07/10/2017] [Accepted: 07/26/2017] [Indexed: 01/02/2023]
Abstract
OBJECTIVE The functional coupling between the fibrillar network and the high-swelling proteoglycans largely determines the mechanical properties of the articular cartilage matrix. The objective of this new study was to show specifically how changes in fibrillar interconnectivity arising from early cartilage degeneration influence transverse stiffness and swelling properties at the tissue level. DESIGN Radial zone transverse layers of cartilage matrix were obtained from intact and mildly degenerate bovine patellae. Each layer was then subdivided to assess tensile stiffness, free-swelling response, glycosaminoglycan (GAG) content, and micro- and ultra-structural features. RESULTS The tensile modulus was significantly lower and the degree of swelling significantly higher for the degenerate matrix compared to the intact. Scanning electron microscopy revealed a homogeneous response to transverse strain in the intact cartilage, whereas large non-fibrillar spaces between fibril aggregates were visible in the degenerate matrix. Although there were no significant differences in GAG content it did correlate significantly with stiffness and swelling in the intact samples but not in the degenerate. CONCLUSIONS The lower degree of fibril network interconnectivity in the degenerate matrix led to both a decreased transverse stiffness and reduced resistance to osmotic swelling. This network 'de-structuring' also resulted in a reduced functional interaction between the fibrillar network and the proteoglycans. The study provides new insights into the role of the fibrillar network and how changes in the network arising from the degenerative cascade will influence tissue level behaviour.
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Workman J, Thambyah A, Broom N. The influence of early degenerative changes on the vulnerability of articular cartilage to impact-induced injury. Clin Biomech (Bristol, Avon) 2017; 43:40-49. [PMID: 28199881 DOI: 10.1016/j.clinbiomech.2017.01.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 11/01/2016] [Accepted: 01/03/2017] [Indexed: 02/07/2023]
Abstract
BACKGROUND Recently, the structural changes in a bovine model of early degeneration were validated by our research group to be analogous to that in early human osteoarthritis. The hypothesis of this study was that the structural changes associated with increasing levels of degeneration would lead to higher levels of tissue damage in response to impact induced injury. METHODS A total of forty bovine patellae were obtained for this study. Cartilage-on-bone samples were extracted from the distal lateral quarter, a region known to be affected by varying levels of degeneration. A single impact drop test was applied to these samples delivering 2.3J of energy. A dynamic load cell and image capture at 2000fps allowed for the calculation of the reaction stress and coefficient of restitution. The extent of tissue damage was examined from the micro to ultrastructural levels using differential interference contrast optical microscopy and scanning electron microscopy respectively. FINDINGS The impact mechanical properties of mildly degenerate articular cartilage were not significantly different but showed a significantly larger amount of structural damage. From comparing the mechanical and structural response of intact and mildly degenerate cartilage, to tissue showing increased macro-scale tissue degeneration, the significance of the surface layer and fibrillar scale transverse interconnectivity in effectively attenuating impact loads is demonstrated in this study. INTERPRETATION This study shows that even though articular cartilage can appear visibly normal under macroscopic observation, the micro-scale structural changes associated with very early stage osteoarthritis can have a significant effect on its vulnerability to impact damage.
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Affiliation(s)
- Joshua Workman
- University of Auckland, 2-6 Park Ave, Grafton, Auckland 1023, New Zealand
| | - Ashvin Thambyah
- University of Auckland, 2-6 Park Ave, Grafton, Auckland 1023, New Zealand.
| | - Neil Broom
- University of Auckland, 2-6 Park Ave, Grafton, Auckland 1023, New Zealand
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11
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Effect of crosslinking in cartilage-like collagen microstructures. J Mech Behav Biomed Mater 2016; 66:138-143. [PMID: 27866057 DOI: 10.1016/j.jmbbm.2016.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 10/03/2016] [Accepted: 10/14/2016] [Indexed: 11/20/2022]
Abstract
The mechanical performance of biological tissues is underpinned by a complex and finely balanced structure. Central to this is collagen, the most abundant protein in our bodies, which plays a dominant role in the functioning of tissues, and also in disease. Based on the collagen meshwork of articular cartilage, we have developed a bottom-up spring-node model of collagen and examined the effect of fibril connectivity, implemented by crosslinking, on mechanical behaviour. Although changing individual crosslink stiffness within an order of magnitude had no significant effect on modelling predictions, the density of crosslinks in a meshwork had a substantial impact on its behaviour. Highly crosslinked meshworks maintained a 'normal' configuration under loading, with stronger resistance to deformation and improved recovery relative to sparsely crosslinked meshwork. Stress on individual fibrils, however, was higher in highly crosslinked meshworks. Meshworks with low numbers of crosslinks reconfigured to disease-like states upon deformation and recovery. The importance of collagen interconnectivity may provide insight into the role of ultrastructure and its mechanics in the initiation, and early stages, of diseases such as osteoarthritis.
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Nickien M, Thambyah A, Broom ND. How a radial focal incision influences the internal shear distribution in articular cartilage with respect to its zonally differentiated microanatomy. J Anat 2015. [PMID: 26198817 DOI: 10.1111/joa.12350] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Articular surface fibrillation and the loss of both transverse interconnectivity and zonal differentiation are indicators of articular cartilage (AC) degeneration. However, exactly how these structural features affect the load-redistributing properties of cartilage is still poorly understood. This study investigated how a single radial incision made to varying depths with respect to the primary zones of AC influenced its deformation response to compression. Three depths of incision were applied to cartilage-on-bone tissue blocks: one not exceeding the transition zone; one into the mid-radial zone; and one down to the calcified cartilage. Also included were non-incised controls. All samples were compressed to a near-equilibrium strain using a flat-faced indenter that incorporated a central relief channel within which the incision could be positioned lengthwise along the channel axis. Employing fixation under load followed by decalcification, the structural responses of the cartilage-on-bone samples were investigated. The study provides an analysis of the micro-morphological response that is characteristic of a completely normal cartilage-on-bone system but which contains a defined degree of disruption induced by the focal radial incision. The resulting loss of transverse continuity of the cartilage with respect to its zonally differentiated structure is shown to lead to an altered pattern of internal matrix shear whose intensity varies with incision depth.
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Affiliation(s)
- Mieke Nickien
- Department of Chemical and Materials Engineering, The University of Auckland, Auckland, New Zealand
| | - Ashvin Thambyah
- Department of Chemical and Materials Engineering, The University of Auckland, Auckland, New Zealand
| | - Neil D Broom
- Department of Chemical and Materials Engineering, The University of Auckland, Auckland, New Zealand
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A review of the combination of experimental measurements and fibril-reinforced modeling for investigation of articular cartilage and chondrocyte response to loading. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2013; 2013:326150. [PMID: 23653665 PMCID: PMC3638701 DOI: 10.1155/2013/326150] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 01/11/2013] [Accepted: 02/23/2013] [Indexed: 11/17/2022]
Abstract
The function of articular cartilage depends on its structure and composition, sensitively impaired in disease (e.g. osteoarthritis, OA). Responses of chondrocytes to tissue loading are modulated by the structure. Altered cell responses as an effect of OA may regulate cartilage mechanotransduction and cell biosynthesis. To be able to evaluate cell responses and factors affecting the onset and progression of OA, local tissue and cell stresses and strains in cartilage need to be characterized. This is extremely challenging with the presently available experimental techniques and therefore computational modeling is required. Modern models of articular cartilage are inhomogeneous and anisotropic, and they include many aspects of the real tissue structure and composition. In this paper, we provide an overview of the computational applications that have been developed for modeling the mechanics of articular cartilage at the tissue and cellular level. We concentrate on the use of fibril-reinforced models of cartilage. Furthermore, we introduce practical considerations for modeling applications, including also experimental tests that can be combined with the modeling approach. At the end, we discuss the prospects for patient-specific models when aiming to use finite element modeling analysis and evaluation of articular cartilage function, cellular responses, failure points, OA progression, and rehabilitation.
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Further insight into the depth-dependent microstructural response of cartilage to compression using a channel indentation technique. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2013; 2013:358192. [PMID: 24023589 PMCID: PMC3638672 DOI: 10.1155/2013/358192] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 02/07/2013] [Accepted: 02/25/2013] [Indexed: 11/17/2022]
Abstract
Stress relaxation and structural analysis were used to investigate the zonally differentiated microstructural response to compression of the integrated cartilage-on-bone tissue system. Fifteen cartilage-on-bone samples were divided into three equal groups and their stress relaxation responses obtained at three different levels of axial compressive strain defined as low (~20%), medium (~40%) and high (~60%). All tests were performed using a channel indenter which included a central relief space designed to capture the response of the matrix adjacent to the directly loaded regions. On completion of each stress relaxation test and while maintaining the imposed axial strain, the samples were formalin fixed, decalcified, and then sectioned for microstructural analysis. Chondron aspect ratios were used to determine the extent of relative strain at different zonal depths. The stress relaxation response of cartilage to all three defined levels of axial strain displayed an initial highly viscous response followed by a significant elastic response. Chondron aspect ratio measurements showed that at the lowest level of compression, axial deformation was confined to the superficial cartilage layer, while in the medium and high axial strain samples the deformation extended into the midzone. The cells in the deep zone remained undeformed for all compression levels.
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Nickien M, Thambyah A, Broom N. How changes in fibril-level organization correlate with the macrolevel behavior of articular cartilage. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2013; 5:495-509. [PMID: 23554314 DOI: 10.1002/wsbm.1220] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The primary structural components of articular cartilage are the zonally differentiated interconnected network of collagen fibrils and proteoglycans, the latter having the potential to bind large amounts of water. Both components exist in a coupled relationship that gives rise to its remarkable mechanical properties. The response of cartilage to compression is governed both by the degree to which the hydrated proteoglycans are constrained within this fibrillar network and the ease with which the matrix fluid can be displaced. The functional properties of cartilage are therefore closely linked to the integrity of the fibrillar network. Our current understanding of this network has been derived via studies conducted at the macro, micro, and ultrastructural levels. Of particular interest to joint researchers and clinicians are issues relating to how the network structure varies both directionally and with zonal depth, how its integrity is maintained via mechanisms of fibril interconnectivity, and how it is modified by ageing, degeneration, and trauma. Physical models have been developed to explore modes of interconnectivity. Combined micromechanical and structural studies confirm the critical role that this interconnectivity must play but detailed descriptions at the molecular level remain elusive. Current computationally based models of cartilage have in some cases implemented the fibrillar component, albeit simplistically, as a separate structure. Considering how important a role fibril network interconnectivity plays in actual tissue structure and mechanical behavior, and especially how it changes with degeneration, a major challenge facing joint tissue modellers is how to incorporate such a feature in their models.
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Affiliation(s)
- Mieke Nickien
- Experimental Tissue Mechanics Laboratory, Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand
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Fick JM. How the structural integrity of the matrix can influence the microstructural response of articular cartilage to compression. Connect Tissue Res 2013; 54:83-93. [PMID: 23126382 DOI: 10.3109/03008207.2012.746321] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This study investigated how the structural integrity of healthy, surface-removed (healthy), and degenerate matrices can modify the response of cartilage to compression. Six groups of specimens were loaded up to the onset of consolidation or at full consolidation (N = 30, 5 per group, respectively) and then subsequently chemically fixed to capture the deformed state of the tissues. Creep compression was applied through an 8 mm flat-ended indenter containing a 450 μm diameter central pore, providing a region of high stress that also allowed the tissue samples to deform freely around the indenter pore during compression. Differential interference contrast microscopy was used in order to explore the microstructural responses of the tissues. The results demonstrated that superficial layer removal or tissue degeneration can reduce the observed deformation within the tissue region corresponding to the central pore of the loading indenter. Fibril crimping within the central pore matrix and matrix shear at the indenter edge regions are also reduced by both superficial layer removal and by tissue degeneration. These findings suggest that surface removal or tissue degeneration renders the matrix more susceptible to deformation and can also reduce the tissue's ability to transfer forces over a greater surface area and induce stress within the matrix.
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Affiliation(s)
- James M Fick
- Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand.
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Kim W, Kawcak CE, McIlwraith CW, Firth EC, Broom ND. Histologic and histomorphometric evaluation of midcarpal joint defects in Thoroughbreds raised with and without early conditioning exercise. Am J Vet Res 2012; 73:498-507. [PMID: 22452496 DOI: 10.2460/ajvr.73.4.498] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To describe and measure histologic features of midcarpal joint cartilage defects in Thoroughbreds and evaluate the influence of early conditioning exercise on defect development. SAMPLE 24 midcarpal joints from twelve 18-month-old Thoroughbreds. PROCEDURES Midcarpal joints from 12 horses (6 exercised spontaneously at pasture only and 6 given additional conditioning exercise beginning at a mean age of 3 weeks were evaluated. Gross cartilage defects were assessed histologically. Third and radial carpal bones were categorized with regard to the presence or absence of calcified cartilage (CC) abnormalities at the dorsoproximal and dorsodistal articular surfaces, respectively; histomorphometric assessment and statistical analysis were conducted for the third carpal bone. RESULTS Number and severity of defects did not appear different between exercise groups. Nine third or radial carpal bones had thickened CC with microcracks, matrix and osteochondral junction changes, and increased vascularity, without histologic changes in the hyaline cartilage. Third carpal bones with CC abnormalities had significantly thicker CC (452 vs 228 μm) than did those without CC abnormalities in the evaluated region. However, in the same region, there were no significant differences in hyaline cartilage thickness (681 vs 603 μm), vascular channel area in the subchondral bone (624,894 vs 490,320 μm(2)), or number of vascular channels (15.9 vs 18.0). CONCLUSIONS AND CLINICAL RELEVANCE Early exercise did not appear to influence the distribution or severity of cartilage defects in the midcarpal joint. Calcified cartilage abnormalities beneath the undisrupted hyaline cartilage in the dorsoproximal aspect of the third carpal bone may represent the first changes in the pathogenesis of midcarpal osteochondral disease.
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Affiliation(s)
- Woong Kim
- Tissue Mechanics Laboratory, Department of Chemical and Materials Engineering, Faculty of Engineering, University of Auckland, Auckland 1142, New Zealand
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Bernhard JC, Panitch A. Synthesis and characterization of an aggrecan mimic. Acta Biomater 2012; 8:1543-50. [PMID: 22248525 DOI: 10.1016/j.actbio.2011.12.029] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 10/26/2011] [Accepted: 12/22/2011] [Indexed: 10/14/2022]
Abstract
Aggrecan (AGG) is a large, aggregating proteoglycan present throughout the body, but predominantly found in articular cartilage. The principle features of AGG, its hyaluronan (HA) binding domain and its abundance of covalently attached glycosaminoglycans (GAGs), make it an essential component of the functional ability of articular cartilage. Current tissue engineering constructs have attempted to stimulate AGG production, but have been unable to produce adequate amounts of mature AGG, and hence have suffered a mismatch in mechanical properties. To address these deficiencies, an AGG mimic was synthesized to match AGG functional properties and provide greater control within tissue engineering constructs. Chondroitin sulfate was functionalized with HA-specific binding peptides to replicate both the GAG presence and HA-binding ability of AGG, respectively. Upon characterization and testing, the mimic was able to effectively bind to HA, increase the compressive strength of cartilage extracellular matrix-based constructs, and protect the other extracellular matrix (ECM) components from degradation, replicating the important functions of AGG. In particular, the mimic produced a 78% increase in compressive strength of the ECM-based constructs, and was able to significantly reduce the degradation of both HA and collagen. The initial characterization of the newly synthesized AGG mimic demonstrates its potential in tissue engineering constructs, and provides an essential basis for more explorative studies of the AGG mimic's abilities as an AGG substitute and beyond.
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Tallents RH, Stein S, Macher D, Katzberg R, Murphy W. Predisposing and Precipitating Factors in Temporomandibular Disorders. Semin Orthod 2012. [DOI: 10.1053/j.sodo.2011.09.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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20
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Balasubramanian P, Prabhakaran MP, Sireesha M, Ramakrishna S. Collagen in Human Tissues: Structure, Function, and Biomedical Implications from a Tissue Engineering Perspective. POLYMER COMPOSITES – POLYOLEFIN FRACTIONATION – POLYMERIC PEPTIDOMIMETICS – COLLAGENS 2012. [DOI: 10.1007/12_2012_176] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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21
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Xia Y, Mittelstaedt D, Ramakrishnan N, Szarko M, Bidthanapally A. Depth-dependent anisotropies of amides and sugar in perpendicular and parallel sections of articular cartilage by Fourier transform infrared imaging. Microsc Res Tech 2011; 74:122-32. [PMID: 21274999 PMCID: PMC3043386 DOI: 10.1002/jemt.20881] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Full thickness blocks of canine humeral cartilage were microtomed into both perpendicular sections and a series of 100 parallel sections, each 6 μm thick. Fourier transform infrared (IR) imaging was used to image each tissue section eleven times under different IR polarizations (from 0° to 180° polarization states in 20° increments and with an additional 90° polarization), at a spatial resolution of 6.25 μm and a wavenumber step of 8 cm⁻¹. With increasing depth from the articular surface, amide anisotropies increased in the perpendicular sections and decreased in the parallel sections. Both types of tissue sectioning identified a 90° difference between amide I and amide II in the superficial zone (SZ) of cartilage. The fibrillar distribution in the parallel sections from the SZ was shown to not be random. Sugar had a weak but recognizable anisotropy in the upper part of the radial zone (RZ) in the perpendicular sections. The depth-dependent anisotropic data were fitted with a theoretical equation that contained three signature parameters, which illustrate the arcade structure of collagens with the aid of a fibril model. Fourier-transform IR imaging of both perpendicular and parallel sections provides the possibility of determining the three-dimensional macromolecular structures in articular cartilage. Being sensitive to the orientation of the macromolecular structure in healthy articular cartilage aids the prospect of detecting the early onset of the tissue degradation that may lead to pathological conditions such as osteoarthritis.
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Affiliation(s)
- Yang Xia
- Department of Physics and Center for Biomedical Research, Oakland University, Rochester, Michigan 48309, USA.
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22
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Bevill SL, Thambyah A, Broom ND. New insights into the role of the superficial tangential zone in influencing the microstructural response of articular cartilage to compression. Osteoarthritis Cartilage 2010; 18:1310-8. [PMID: 20633674 DOI: 10.1016/j.joca.2010.06.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Revised: 06/04/2010] [Accepted: 06/19/2010] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The purpose of this study was to characterize the microstructural response of healthy cartilage in a perturbed physical environment to compressive loading with a novel channel indentation device. Manipulation of the cartilage physical environment was achieved through (1) removal of the superficial tangential zone (STZ) and (2) varying the saline bathing solution concentration. DESIGN Cartilage-on-bone blocks were subjected to creep loading under a nominal stress of 4.5 MPa via an indenter consisting of two rectangular platens separated by a narrow channel relief space to create a specific region where cartilage would not be directly loaded. Each sample was fixed in its near-equilibrium deformed state, after which the cartilage microstructure was examined using differential interference contrast (DIC) optical microscopy and scanning electron microscopy (SEM). The cartilage bulge in the channel relief space was studied in detail. RESULTS STZ removal altered the indentation response at the macro- and microstructural levels. Specifically, the strain in the directly compressed regions was reduced (P=0.012) and the bulge height in the channel relief space was greater (P<0.0001) in the STZ-removed compared with the surface-intact samples. The bulge height in the STZ-removed group was always less than the preloaded cartilage thickness. There was intense shear in the non-directly-loaded regions of intact-cartilage but not in STZ-removed cartilage. Bathing solution concentration influenced only the STZ-removed group, where lower concentrations produced significantly abrupt transitions in matrix continuity between the directly compressed and adjacent non-directly-loaded cartilage (P=0.012). CONCLUSIONS This study showed that while the surface layer was important in distributing loads away from directly-loaded regions, so were other factors such as the matrix fibrillar interconnectivity, swelling potential, and tissue anisotropy.
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Affiliation(s)
- S L Bevill
- Biomaterials Laboratory, Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand.
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Anisotropic dynamic changes in the pore network structure, fluid diffusion and fluid flow in articular cartilage under compression. Biomaterials 2010; 31:3117-28. [PMID: 20144846 DOI: 10.1016/j.biomaterials.2010.01.102] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 01/15/2010] [Indexed: 10/19/2022]
Abstract
A compression cell designed to fit inside an NMR spectrometer was used to investigate the in situ mechanical strain response, structural changes to the internal pore structure, and the diffusion and flow of interstitial water in full-thickness cartilage samples as it was deforming dynamically under a constant compressive load (pressure). We distinguish between the hydrostatic pressure acting on the interstitial fluid and the pore pressure acting on the cartilage fibril network. Our results show that properties related to the pore matrix microstructure such as diffusion and hydraulic conductivity are strongly influenced by the hydrostatic pressure in the interstitial fluid of the dynamically deforming cartilage which differ significantly from the properties measured under static i.e. equilibrium loading conditions (when the hydrostatic pressure has relaxed back to zero). The magnitude of the hydrostatic fluid pressure also appears to affect the way cartilage's pore matrix changes during deformation with implications for the diffusion and flow-driven fluid transport through the deforming pore matrix. We also show strong evidence for a highly anisotropic pore structure and deformational dynamics that allows cartilage to deform without significantly altering the axial porosity of the matrix even at very large strains. The insensitivity of the axial porosity to compressive strain may be playing a critical function in directing the flow of pressurized interstitial fluid in the compressed cartilage to the surface, to support the load, and provide a protective interfacial fluid film that 'weeps' out from the deforming tissue and thereby enhances the (elasto)hydrodynamic efficacy of sliding joints. Our results appear to show a close synergy between the structure of cartilage and both the hydrodynamic and boundary lubrication mechanisms.
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Kim W, Kawcak CE, McIlwraith CW, Firth EC, McArdle BH, Broom ND. Influence of early conditioning exercise on the development of gross cartilage defects and swelling behavior of cartilage extracellular matrix in the equine midcarpal joint. Am J Vet Res 2009; 70:589-98. [PMID: 19405897 DOI: 10.2460/ajvr.70.5.589] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate the influence of early conditioning exercise on the development of gross cartilage defects and swelling behavior of cartilage extracellular matrix (ECM) in the midcarpal joint of horses. ANIMALS 12 Thoroughbreds. PROCEDURES 6 horses underwent early conditioning exercise from birth to 18 months of age (CONDEX group), and 6 horses were used as control animals (PASTEX group). The horses were euthanized at 18 months of age, and the midcarpal joints were harvested. Gross defects of the cartilage surface were classified and mapped. Opposing surfaces of the third and radial carpal bones were used to quantify swelling behavior of the cartilage ECM. RESULTS A wide range of gross defects was detected in the cartilage on the opposing surfaces of the bones of the midcarpal joint; however, there was no significant difference between the CONDEX and PASTEX groups. Similarly, no significant difference in swelling behavior of the cartilage ECM was evident between the CONDEX and PASTEX groups. CONCLUSIONS AND CLINICAL RELEVANCE In the study reported here, we did not detect negative influences of early conditioning exercise on the prevalence of gross defects in cartilage of the midcarpal joint or the quality of the cartilage ECM as defined by swelling behavior. These results suggested that early conditioning exercise may be used without negative consequences for the midcarpal joint and the cartilage ECM of the third and radial carpal bones.
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Affiliation(s)
- Woong Kim
- Biomaterials Laboratory, Department of Chemical and Materials Engineering, Faculty of Engineering, University of Auckland, Auckland 1142, New Zealand
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Thambyah A, Broom N. On new bone formation in the pre-osteoarthritic joint. Osteoarthritis Cartilage 2009; 17:456-63. [PMID: 18977155 DOI: 10.1016/j.joca.2008.09.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Accepted: 09/06/2008] [Indexed: 02/02/2023]
Abstract
OBJECTIVE This study investigated the structural alterations in the osteochondral junction, traversing the intact-to-lesion regions, with the aim of elucidating the way in which the pre-osteoarthritic (pre-OA) state progresses to fully developed osteoarthritis (OA). METHOD Thirty bovine patellae showing varying degrees of degeneration, with lesions located in the distal-lateral quarter, were used for this study. Cartilage-on-bone blocks were cut along the lateral facet to include both the lesion site in the distal end and the intact site in the proximal end. The blocks were formalin-fixed, mildly decalcified and microtomed to obtain 30 microm - thick osteochondral slices. Using differential interference contrast optics, the tissue microstructure was captured at high resolution in its fully hydrated state. RESULTS There were structural changes in the osteochondral junction beneath the still-intact articular cartilage adjacent to the lesion site. The changes observed in traversing from the intact to the lesion site exhibited characteristics that were strikingly similar to those associated with primary bone formation. The evidence suggests that disruption of the cartilage continuum by a lesion has wider mechanobiological consequences at the osteochondral junction. CONCLUSION The progression of OA appears to involve new bone formation adjacent to lesion sites. We hypothesise that the new bone spicules that appear in regions beneath intact cartilage adjacent to lesion sites provide a snapshot of the elusive pre-OA state.
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Affiliation(s)
- A Thambyah
- Biomaterials Laboratory, Department of Chemical and Materials Engineering, University of Auckland, New Zealand
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Thambyah A, Broom N. On how degeneration influences load-bearing in the cartilage-bone system: a microstructural and micromechanical study. Osteoarthritis Cartilage 2007; 15:1410-23. [PMID: 17689989 DOI: 10.1016/j.joca.2007.05.006] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2007] [Accepted: 05/01/2007] [Indexed: 02/02/2023]
Abstract
OBJECTIVE This study investigated the microanatomical response to compression of intact and degenerate cartilage-on-bone samples with the aim of elucidating the functional consequences of articular surface disruption and related matrix changes. METHOD Two groups of mature bovine patellae were identified at the time of harvest; those with intact cartilage and those with cartilage exhibiting mild to severe degeneration. Cartilage-on-bone samples were statically compressed (7 MPa) to near-equilibrium using an 8-mm diameter cylindrical indenter, and then formalin-fixed in this deformed state. Following mild decalcification full-depth cartilage-bone sections, incorporating the indentation profile and beyond, were studied in their fully hydrated state using differential interference contrast optical microscopy (DIC). RESULTS Differences in matrix texture, degree of disruption of the articular surface layer (or its complete absence), number of tidemarks and absence or presence of vascularization of the calcified cartilage zone were all observable features that provided clear differentiation between the normal and degenerate tissues. Under load a chevron-type shear discontinuity characterized those samples in which the strain-limiting surface layer was still largely intact. The extent to which this shear discontinuity advanced into the adjacent non-directly loaded cartilage continuum was influenced by the integrity of the cartilage general matrix. For those tissues deficient in a strain-limiting articular surface there was no shear discontinuity, the cartilage deformation field was instead shaped primarily by its osteochondral attachment and a laterally-directed compressive collapse of a much weakened matrix. In the degenerate samples the altered matrix textures associated with different regions of the deformation field are interpreted in terms of an intrinsic fibrillar architecture that is weakened by two fundamental processes: (1) a de-structuring resulting from a reduction in connectivity between fibrils and (2) subsequent aggregation of these now disconnected fibrils. CONCLUSION DIC microscopy provides a high-resolution description of the integrated osteochondral tissue system across the full continuum of matrices, from normal to severely degenerate. Our study demonstrates the important functional role played by the strain-limiting articular surface, the consequences associated with its disruption, as well as the loss of effective stress transmission associated with a 'de-structured' general matrix. The study also provides new insights into the integration of cartilage with both its subchondral substrate and the wider continuum of non-directly loaded cartilage.
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Affiliation(s)
- A Thambyah
- Biomaterials Laboratory, Department of Chemical and Materials Engineering, University of Auckland, New Zealand
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Taylor ZA, Kirk TB, Miller K. Confocal arthroscopy-based patient-specific constitutive models of cartilaginous tissues—I: development of a microstructural model. Comput Methods Biomech Biomed Engin 2007; 10:307-16. [PMID: 17671863 DOI: 10.1080/10255840701336794] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Current development of a laser scanning confocal arthroscope within our school will enable 3D microscopic imaging of joint tissues in vivo. Such an instrument could be useful, for example, in assessing the microstructural condition of the living tissues without physical biopsy. It is envisaged also that linked to a suitable microstructural constitutive formulation, such imaging could allow non-invasive patient-specific estimation of tissue mechanical performance. Such a procedure could have applications in surgical planning and simulation, and assessment of engineered tissue replacements, where tissue biopsy is unacceptable. In this first of two papers the development of a suitable constitutive framework for generating such estimates is reported. A microstructure-based constitutive formulation for cartilaginous tissues is presented. The model extends existing fibre composite-type models and accounts for strain-rate sensitivity of the tissue mechanical response through incorporation of a viscoelastic fibre phase. Importantly, the model is constructed so as to allow direct incorporation of structural data from confocal images. A finite element implementation of the formulation suitable for incorporation within commercial codes is also presented.
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Affiliation(s)
- Zeike A Taylor
- Intelligent Systems for Medicine Laboratory, School of Mechanical Engineering, The University of Western Australia, Crawley/Perth, WA, Australia
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Thambyah A, Broom N. Micro-anatomical response of cartilage-on-bone to compression: mechanisms of deformation within and beyond the directly loaded matrix. J Anat 2007; 209:611-22. [PMID: 17062019 PMCID: PMC2100340 DOI: 10.1111/j.1469-7580.2006.00646.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The biomechanical function of articular cartilage relies crucially on its integration with both the subchondral bone and the wider continuum of cartilage beyond the directly loaded contact region. This study was aimed at visualizing, at the microanatomical level, the deformation response of cartilage including that of the non-directly loaded continuum. Cartilage-on-bone samples from bovine patellae were loaded in static compression until a near-equilibrium deformation was achieved, and then chemically fixed in this deformed state. Full-depth cartilage-bone sections, incorporating the indentation profile and beyond, were studied in their fully hydrated state using differential interference contrast microscopy. Morphometric measurements of the indented profile were used in combination with a force analysis of the tangential layer to investigate the extent to which the applied force is attenuated in moving away from the directly loaded region. This study provides microscopic evidence of a structure-related response in the transitional zone of the cartilage matrix. It is manifested as an intense chevron-type shear discontinuity arising from the constraints provided by both the strain-limiting articular surface and the osteochondral attachment. The discontinuity persists well into the non-directly loaded continuum of cartilage and is proposed as a force attenuation mechanism. The structural and biomechanical analyses presented in this study emphasize the important role of the complex microanatomy of cartilage, highlighting the interconnectivity and optimal recruitment of the load-bearing elements throughout the zonally differentiated cartilage depth.
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Affiliation(s)
- Ashvin Thambyah
- Biomaterials Laboratory, Department of Chemical and Materials Engineering, University of Auckland, New Zealand
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Deng X, Farley M, Nieminen MT, Gray M, Burstein D. Diffusion tensor imaging of native and degenerated human articular cartilage. Magn Reson Imaging 2007; 25:168-71. [PMID: 17275610 DOI: 10.1016/j.mri.2006.10.015] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2006] [Revised: 09/18/2006] [Indexed: 10/23/2022]
Abstract
Diffusion tensor imaging (DTI) is potentially sensitive to collagen degeneration in cartilage. In this study, DTI was measured on human cartilage samples with interventions of trypsin and collagenase. The measured preferred diffusion direction was consistent with the zonal structure of collagen network. The glycosaminoglycan concentration decreased and apparent diffusion coefficient increased with both interventions. The fractional anisotropy (FA) was not affected by trypsin and showed a slight increase with combined trypsin and collagenase intervention. DTI in cartilage is technically challenging due to the low FA and the almost undetectable change with collagen disruption seen here.
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Affiliation(s)
- Xiang Deng
- Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
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30
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Richmon JD, Sage A, Wong WV, Chen AC, Sah RL, Watson D, Watston D. Compressive biomechanical properties of human nasal septal cartilage. ACTA ACUST UNITED AC 2007; 20:496-501. [PMID: 17063745 DOI: 10.2500/ajr.2006.20.2932] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Nasal septal cartilage is frequently used in nasal reconstruction and is a common source of chondrocytes for cartilage tissue engineering. The biomechanical properties of septal cartilage have yet to be fully defined and this limits the ability to compare it to the various alternative tissue-implant materials or tissue-engineered neocartilage. Given the unique structure and orientation of the septum within the nose, we sought to investigate anisotropic behaviors of septal cartilage in compression and correlate this to the concentration of glycosaminoglycans (GAG) and collagen within the cartilage. METHODS Human nasal septal cartilage specimens were tested in confined compression, with each sample analyzed in a medial orientation and also either a vertical or caudal-cephalic orientation, with the order of tests randomized. The equilibrium confined compression (aggregate) modulus, HAO, and the permeability, kp, at different offset compression levels were obtained for each compression test. After testing, the cartilage samples were solubilized, and the concentrations of GAG and collagen were obtained. RESULTS Forty-nine compression tests (24 medial, 12 vertical, 13 caudal-cephalic) were run on cartilage specimens obtained from 21 patients. There was a significant effect of orientation on compression modulus, HAO, with the vertical (0.7 +/- 0.12 MPa) and caudal-cephalic (0.66 +/- 0.01 MPa) orientations being significantly stiffer (p = 0.05) than the medial orientation (0.44 +/- 0.04 MPa). There was a trend of an orientation effect on kp at 15% offset compression (p = 0.12) and a borderline significant effect of orientation on kp at 30% offset compression (p = 0.05), demonstrating the M orientation to be more permeable than both the vertical and caudal-cephalic orientations. Both univariate and multivariate analysis did not demonstrate a significant effect of order of compression, age, gender, thickness, dry/wet weight, GAG, or collagen on either HAO, or kp values (p > 0.05). CONCLUSION This study provides new information on the compressive properties of septal cartilage along different axes of compression. The results demonstrate that human septal cartilage is anisotropic; the compressive stiffness is higher in the vertical and caudal-cephalic orientations than in the medial orientation. Additionally, the medial orientation tends to have the greatest permeability. The data obtained in this study provide a reference to which various craniofacial reconstruction materials and tissue-engineered neocartilage can be compared.
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Affiliation(s)
- Jeremy D Richmon
- Division of Head and Neck Surgery, University of California, San Diego, and San Diego Veterans Affairs Healthcare System, San Diego, California, 92103, USA.
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31
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Burstein D. MRI for development of disease-modifying osteoarthritis drugs. NMR IN BIOMEDICINE 2006; 19:669-80. [PMID: 16986116 DOI: 10.1002/nbm.1071] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
MRI has advantages as an imaging modality for drug development through its potential to provide information regarding localized morphological parameters, in addition to metrics of the structural and molecular state of cartilage. These metrics have the potential to provide earlier indications of pathology and may progress more rapidly than radiographic measures. These combined scans of localized morphology and matrix parameters will most likely provide a fuller assessment of cartilage state and will improve the cost and practicality of an overall evaluation of cartilage status by MRI. In the first part of this review, the relevant parameters are presented in terms of the information content they might provide in the drug development process. In the second part, applications of the MRI parameters in preclinical and clinical drug development are presented.
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Affiliation(s)
- Deborah Burstein
- Department of Radiology, Beth Israel Deaconess Medical Center, 4 Blackfan Circle, Boston, MA 02115, USA.
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Scott JE, Stockwell RA. Cartilage elasticity resides in shape module decoran and aggrecan sumps of damping fluid: implications in osteoarthrosis. J Physiol 2006; 574:643-50. [PMID: 16581860 PMCID: PMC1817741 DOI: 10.1113/jphysiol.2006.108100] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Accepted: 03/27/2006] [Indexed: 01/01/2023] Open
Abstract
Cartilage ultrastructure is based on collagen fibrils tied together by proteoglycans (PGs). Interfibrillar orthogonal PG bridges ('shape modules') were located by electron histochemistry using Cupromeronic blue methodology. Their frequency and size, similar to those in tendon, cornea, etc., were compatible with biochemical estimates of tissue decoran (formerly decorin), the PG component of shape module bridges. Digestion by hyaluronanase and chondroitinase AC helped to identify aggrecan and decoran and exemplified the destruction of shape modular organization by glycan-splitting agents. The anionic glycosaminoglycan (AGAG) of decoran, dermochondan sulphate (DS, formerly dermatan sulphate), contains L-iduronate, an elastic sugar unit. Chondroitan, keratan (present in aggrecan) and hyaluronan are not similarly elastic but can participate in sliding-filament reversible deformability. Mechanical properties predicted for the interfibrillar bridges accord with anisotropic stress/strain responses of articular cartilage to compressive or tensile stresses. We propose that fluid from pericellular aggrecan-rich domains moves under pressure into the interterritorial fibrillar arrays against the elastic resistance of the shape modules, which return the fluid, post-compression, to its original position. Cartilage is tendon-like, with the addition of expansile aggrecan-rich reservoirs of aqueous shock absorber fluid. Rupture or loss of interfibrillar ties would allow expansile PG to force the collagenous matrix apart, imbibing water, increasing swelling and fissuring--characteristic manifestations of osteoarthrosis (OA), a joint disease of major economic importance. Decoran may be a primary target of the OA disease process.
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Affiliation(s)
- John E Scott
- Chemical Morphology, Medical School, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
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Wilson W, van Burken C, van Donkelaar C, Buma P, van Rietbergen B, Huiskes R. Causes of mechanically induced collagen damage in articular cartilage. J Orthop Res 2006; 24:220-8. [PMID: 16435355 DOI: 10.1002/jor.20027] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Osteoarthritis (OA) is a multifactorial disease, associated with articular cartilage degeneration and eventually joint destruction. The phases of the disease have been described in detail, and mechanical factors play an important role in the initiation of OA, but many questions remain about its etiology. Swelling of cartilage, one of the earliest signs of damage, is proportional to the amount of collagen damage. This strongly suggests that damage to the collagen network is an early event in cartilage degeneration. The goal of this study was to determine the mechanical cause of early collagen damage in articular cartilage after mechanical overloading. Both the shear strain along the fibrils and the maximum fibril strains were evaluated as possible candidates for causing collagen damage. This evaluation was done by comparing the locations of maximum shear and tensile strains with the locations of initial collagen damage after mechanical overloading in bovine explants as found using antibodies directed against denatured type II collagen (Col2-3/4M). Collagen damage could be initiated by excessive shear strains along the collagen fibrils, and by excessive fibrils strains. The locations of collagen damage after mechanical overloading were highly dependent on the cartilage thickness, with thinner cartilage being more susceptible to damage than thicker samples.
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Affiliation(s)
- Wouter Wilson
- Department of Biomedical Engineering, WH 4.118, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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Flachsmann R, Kistler M, Rentzios A, Broom ND. Influence of an initiating microsplit on the resistance to compression-induced rupture of the articular surface. Connect Tissue Res 2006; 47:77-84. [PMID: 16754513 DOI: 10.1080/03008200600584090] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Cartilage-on-bone samples from bovine patellae containing a defined stellar or linear initiating split in the articular surface were incrementally loaded in direct compression with intervening rehydration, until articular surface rupture occurred. All patellae were either normal or exhibited a mild level of surface fibrillation. In all cases the actual loading site was free of disruption. The average rupture stress of the healthy cartilage was significantly higher than that of the mildly degenerate cartilage, and in both tissue categories average rupture stresses were lower for the linear split morphology than for the stellar. We propose that this contrasting rupture behavior is explained by differences in both secondary lineal surface strains associated with the depth of compressive indentation and in the ability of the fibrillar network within the surface layer to re-arrange itself in the localized regions of stress concentration around the initiating split.
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Affiliation(s)
- R Flachsmann
- Biomaterials Research Laboratory, Department of Chemical and Materials Engineering, University of Auckland, New Zealand
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35
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Wilson W, van Donkelaar CC, van Rietbergen R, Huiskes R. The role of computational models in the search for the mechanical behavior and damage mechanisms of articular cartilage. Med Eng Phys 2005; 27:810-26. [PMID: 16287601 DOI: 10.1016/j.medengphy.2005.03.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2004] [Revised: 02/08/2005] [Accepted: 03/11/2005] [Indexed: 10/25/2022]
Abstract
Articular cartilage plays a vital role in the function of diarthrodial joints. Due to osteoarthritis degeneration of articular cartilage occurs. The initial event that triggers the pathological process of cartilage degeneration is still unknown. Cartilage damage due to osteoarthritis is believed to be mechanically induced. Hence, to investigate the initiation of osteoarthritis the stresses and strains in the cartilage must be determined. So far the most common method to accomplish that is finite element analysis. This paper provides an overview of computational descriptions developed for this purpose, and what they can be used for. Articular cartilage composition and structure are discussed in relation with degenerative changes, and how these affect mechanical properties.
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Affiliation(s)
- W Wilson
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
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Akhtar S, Davies JR, Caterson B. Ultrastructural localization and distribution of proteoglycan in normal and scoliotic lumbar disc. Spine (Phila Pa 1976) 2005; 30:1303-9. [PMID: 15928557 DOI: 10.1097/01.brs.0000164284.17039.65] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Comparative ultrastructural study of normal and scoliotic intervertebral discs. OBJECTIVE To examine the ultrastructural organization and distribution of proteoglycan in relation to collagen and elastic fibers in normal and scoliotic discs. SUMMARY OF BACKGROUND The mechanical properties of intervertebral discs depend on the collagens and proteoglycans in the matrix; proteoglycan content and the organization of collagen fibers are altered in degenerate discs. However, little is known about the structural relations among disc components and alterations to them in scoliosis. METHODS Samples of normal and scoliotic disc from individuals aged between 12 and 16 years were fixed in 2.5% glutaraldehyde containing cuprolinic blue and examined by transmission electron microscopy. The sizes and distribution of proteoglycan particles throughout different matrix regions were quantified. RESULTS In anulus fibrosus of normal disc, collagen and elastic fibers in lamellas were covered with small proteoglycan particles in a regular pattern; proteoglycan particles of similar sizes were evenly distributed throughout the matrix. Anulus fibrosus of scoliotic disc contained degenerate collagen lamellas, few elastic fibers, and a pericellular accumulation of large proteoglycan aggregates; scoliotic nucleus pulposus also contained an accumulation of proteoglycan aggregates. Most cells in both regions of scoliotic discs were degenerate and vacuolated. CONCLUSION We provide ultrastructural confirmation of the disruption of the lamellar organization of collagen and elastic fibers in scoliosis. Our observations of altered proteoglycan distribution in scoliotic tissue suggest that impaired proteoglycan turnover plays a key role in the disruption of the structural integrity of the disc in scoliosis.
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Affiliation(s)
- Saeed Akhtar
- School of Optometry, Cardiff School of Biosciences, Cardiff University, United Kingdom.
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Abstract
Cartilage taken from the osteoarthritic bovine patellae was used to investigate the progression of change in the collagenous architecture associated with the development of fibrillated lesions. Differential interference contrast optical microscopy using fully hydrated radial sections revealed a continuity in the alteration of the fibrillar architecture in the general matrix consistent with the progressive destructuring of a native radial arrangement of fibrils repeatedly interconnected in the transverse direction via a non-entwinement-based linking mechanism. This destructuring is shown to occur in the still intact regions adjacent to the disrupted lesion thus rendering them more vulnerable to radial rupture. Two contrasting modes of surface rupture were observed and these are explained in terms of the absence or presence of a skewed structural weakening of the intermediate zone. A mechanism of surface rupture initiation based on simple bi-layer theory is proposed to account for the intensification of surface ruptures observed in the intact regions on advancing towards the fibrillation front. Focusing specifically on the primary collagen architecture in the cartilage matrix, this study proposes a pathway of change from intact to overt disruption within a unified structural framework.
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Affiliation(s)
- Neil D Broom
- Biomaterials Laboratory, Department of Chemical and Materials Engineering, University of Auckland, New Zealand.
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Muehleman C, Majumdar S, Issever AS, Arfelli F, Menk RH, Rigon L, Heitner G, Reime B, Metge J, Wagner A, Kuettner KE, Mollenhauer J. X-ray detection of structural orientation in human articular cartilage. Osteoarthritis Cartilage 2004; 12:97-105. [PMID: 14723869 DOI: 10.1016/j.joca.2003.10.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To determine the feasibility of detecting the structural orientation in cartilage with Diffraction Enhanced X-Ray Imaging. DESIGN Human tali and femoral head specimens were Diffraction Enhanced X-Ray Imaged (DEI) at the SYRMEP beamline at Elettra at various energy levels to detect the architectural arrangement of collagen within cartilage. DEI utilizes a monochromatic and highly collimated beam, with an analyzer crystal that selectively weights out photons according to the angle they have been deviated with respect to the original direction. This provides images of very high contrast, and with the rejection of X-ray scatter. RESULTS DEI allowed the visualization of articular cartilage and a structural orientation, resembling arcades, within. CONCLUSION Our diffraction enhanced images represent the first radiographic detection of the structural orientation in cartilage. Our data are in line with previous studies on the structural organization of joint cartilage. They confirm the model of a vaulting system of collagen fiber bundles interrupted by proteoglycan aggregates.
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Affiliation(s)
- Carol Muehleman
- Department of Anatomy and Cell Biology, Rush Medical College, IL 60612, Chicago, USA.
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Broom ND, Flachsmann R. Physical indicators of cartilage health: the relevance of compliance, thickness, swelling and fibrillar texture. J Anat 2003; 202:481-94. [PMID: 12846470 PMCID: PMC1571108 DOI: 10.1046/j.1469-7580.2003.00184.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study uses a bovine patella model to compare the relative merits of on-bone compliance and thickness measurements, free-swelling behaviour, and structural imaging with differential interference contrast (DIC) light microscopy to assess the biomechanical normality of the cartilage matrix. The results demonstrate that across a spectrum of cartilage tissues from immature, mature, through to mildly degenerate, and all with intact articular surfaces, there is a consistent pattern of increased free swelling of the isolated general matrix with age and degeneration. High swelling was always associated with major structural alterations of the general matrix that were readily imaged using DIC light microscopy. Conversely, for all tissue groups, no relationship was observed between thickness vs. compliance and compliance vs. general matrix swelling. Only in the proximal aspects of the normal mature and degenerate tissues was there a correlation between thickness and general matrix swelling. Free-swelling measurements combined with fibrillar texture imaging using DIC light microscopy are therefore recommended as providing a reliable and quick method of assessing the biomechanical condition of the cartilage general matrix.
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Affiliation(s)
- Neil D Broom
- Biomechanics Laboratory, Department of Chemical & Materials Engineering, University of Auckland, New Zealand.
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40
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Boyan BD, Dean DD, Lohmann CH, Niederauer GG, McMillan J, Sylvia VL, Schwartz Z. Cartilage regeneration. Oral Maxillofac Surg Clin North Am 2002; 14:105-16. [DOI: 10.1016/s1042-3699(02)00017-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
The extracellular framework and two-thirds of the dry mass of adult articular cartilage are polymeric collagen. Type II collagen is the principal molecular component in mammals, but collagens III, VI, IX, X, XI, XII and XIV all contribute to the mature matrix. In developing cartilage, the core fibrillar network is a cross-linked copolymer of collagens II, IX and XI. The functions of collagens IX and XI in this heteropolymer are not yet fully defined but, evidently, they are critically important since mutations in COLIX and COLXI genes result in chondrodysplasia phenotypes that feature precocious osteoarthritis. Collagens XII and XIV are thought also to be bound to fibril surfaces but not covalently attached. Collagen VI polymerizes into its own type of filamentous network that has multiple adhesion domains for cells and other matrix components. Collagen X is normally restricted to the thin layer of calcified cartilage that interfaces articular cartilage with bone.
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Affiliation(s)
- David Eyre
- Orthopaedic Research Laboratories, Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, Washington 98195-6500, USA.
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42
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Broom N, Chen MH, Hardy A. A degeneration-based hypothesis for interpreting fibrillar changes in the osteoarthritic cartilage matrix. J Anat 2001; 199:683-98. [PMID: 11787822 PMCID: PMC1468386 DOI: 10.1046/j.1469-7580.2001.19960683.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The collagen fibrillar architectures in the general matrix of cartilage slices removed from both normal and osteoarthritic femoral heads were examined by both differential interference light microscopy and scanning electron microscopy. Whereas the normal general matrix contained a finely differentiated pseudo-random weave of fibrils developed from an interconnected array of radial elements, the osteoarthritic general matrix was characterised by the presence of structurally distinct regions consisting of strongly aligned radial bundles of fibrils and associated intense tangles or 'knotted' features. Simple structural models were developed to explore possible transformation structures based on two different types of interconnectivity in the three-dimensional fibrillar network. These models support the hypothesis that the distinctive ultrastructural features of the osteoarthritic general matrix can develop as a consequence of largely passive degradative changes occurring in the fibrillar weave originally present in the normal matrix. This could, in principle, occur independently of any new structure that might develop as a consequence of any upregulation of collagen associated with the osteoarthritic process.
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Affiliation(s)
- N Broom
- Biomechanics Laboratory, Department of Mechanical Engineering, University of Auckland, New Zealand.
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Abstract
Cartilage degenerative diseases affect millions of people. Our understanding of these diseases and our ability to establish efficacious treatment strategies have been confounded by the difficulty of nondestructively evaluating the state of cartilage. Imaging strategies that allow visualization of cartilage integrity would revolutionize the field by allowing us to visualize early stages of degeneration and thus to evaluate predisposing factors for cartilage disease and changes resulting from interventions (eg, therapies) in culture studies, tissue-engineered systems, animal models, and in vivo in humans. Here we briefly review current state-of-the-art MRI strategies relevant to understanding and following treatment in early cartilage degeneration. We review MRI as applied to the assessment of the whole joint, of cartilage as a whole (as an organ), of cartilage tissue, and of cartilage molecular composition and structure. Each of these levels is amenable to assessment by MRI and offers different information that, in the long run, will serve as an important element of cartilage imaging.
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Affiliation(s)
- D Burstein
- Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA.
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Abstract
The swelling behaviour of the general matrix of both normal and abnormally softened articular cartilage was investigated in the context of its relationship to the underlying subchondral bone, the articular surface, and with respect to the primary structural directions represented in its strongly anisotropic collagenous architecture. Swelling behaviours were compared by subjecting tissue specimens under different modes of constraint to a high swelling bathing solution of distilled water and comparing structural changes imaged at the macroscopic, microscopic and ultrastructural levels of resolution. Near zero swelling was observed in the isolated normal general matrix with minimal structural change. By contrast the similarly isolated softened general matrix exhibited large-scale swelling in both the transverse and radial directions. This difference in dimensional stability was attributed to fundamentally different levels of fibril interconnectivity between the 2 matrices. A model of structural transformation is proposed to accommodate fibrillar rearrangements associated with the large-scale swelling in the radial and transverse directions in the softened general matrix.
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Affiliation(s)
- M H Chen
- Department of Mechanical Engineering, University of Auckland, New Zealand
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