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Changoor A, Garon M, Quenneville E, Savard P, Buschmann MD, Hurtig MB. Non-invasive electroarthrography measures cartilage in live horses and correlates to direct measurements of cartilage streaming potentials in weight bearing regions of equine metacarpophalangeal joints. Osteoarthritis Cartilage 2024:S1063-4584(24)01163-4. [PMID: 38679283 DOI: 10.1016/j.joca.2024.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 04/08/2024] [Accepted: 04/22/2024] [Indexed: 05/01/2024]
Abstract
OBJECTIVE To perform non-invasive Electroarthrography (EAG) on live horses and establish relationships between EAG and direct measurements of cartilage streaming potentials in weight bearing areas of the equine metacarpophalangeal joint. DESIGN EAG was performed bilaterally on the metacarpophalangeal joints of live horses (n = 3). Separate experiments used metacarpophalangeal joint explants (n = 11) to measure EAG obtained during simulated loading followed by direct measurements of cartilage streaming potentials on joint surfaces using the Arthro-BST probe. Joints were assigned to relatively normal (n = 5) and mildly degraded (n = 6) groups based on histological scoring of Safranin-O/Fast Green stained sections. RESULTS EAG, involving application of electrodes to skin surrounding the joint and repeated weight shifting, was well-tolerated in live horses. One pair of distal forelimbs were available for analogous ex vivo EAG testing and measurements were strongly correlated to in vivo EAG measurements obtained on the same joints (r = 0.804, p = 0.016, n = 8). Both indirect (EAG) and direct (Arthro-BST) measurements of cartilage streaming potentials distinguished between normal and mildly degraded cartilage with statistically significant differences at 5 of 6 and 4 of 6 electrodes during simulated standing and walking, respectively. Strong and moderate correlations for weight bearing regions on the dorsal phalanx and central metacarpus were detected during both standing and walking. At the metacarpus/sesamoid interface a moderate correlation occurred during walking. CONCLUSION Non-invasive EAG was used successfully in a clinical scenario and correlated to direct measurements of streaming potentials in weight bearing cartilage. These data support the potential of EAG to contribute to the diagnosis and treatment of degenerative joint diseases.
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Affiliation(s)
- Adele Changoor
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada; Department of Surgery, Department of Laboratory Medicine & Pathobiology, Department of Materials Science & Engineering, University of Toronto, Toronto, Ontario, Canada.
| | | | | | - Pierre Savard
- Biomedical and Electrical Engineering, École Polytechnique, Montréal, Québec, Canada
| | - Michael D Buschmann
- Department of Bioengineering, George Mason University, Fairfax, Virginia, United States
| | - Mark B Hurtig
- Comparative Orthopaedic Research Laboratory, Department of Clinical Studies, University of Guelph, Guelph, Ontario, Canada
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2
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Maciulaitis J, Miskiniene M, Rekštytė S, Bratchikov M, Darinskas A, Simbelyte A, Daunoras G, Laurinaviciene A, Laurinavicius A, Gudas R, Malinauskas M, Maciulaitis R. Osteochondral Repair and Electromechanical Evaluation of Custom 3D Scaffold Microstructured by Direct Laser Writing Lithography. Cartilage 2021; 13:615S-625S. [PMID: 31072136 PMCID: PMC8804810 DOI: 10.1177/1947603519847745] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVE The objective of this study was to assess a novel 3D microstructured scaffold seeded with allogeneic chondrocytes (cells) in a rabbit osteochondral defect model. DESIGN Direct laser writing lithography in pre-polymers was employed to fabricate custom silicon-zirconium containing hybrid organic-inorganic (HOI) polymer SZ2080 scaffolds of a predefined morphology. Hexagon-pored HOI scaffolds were seeded with chondrocytes (cells), and tissue-engineered cartilage biocompatibility, potency, efficacy, and shelf-life in vitro was assessed by morphological, ELISA (enzyme-linked immunosorbent assay) and PCR (polymerase chain reaction) analysis. Osteochondral defect was created in the weight-bearing area of medial femoral condyle for in vivo study. Polymerized fibrin was added to every defect of 5 experimental groups. Cartilage repair was analyzed after 6 months using macroscopical (Oswestry Arthroscopy Score [OAS]), histological, and electromechanical quantitative potential (QP) scores. Collagen scaffold (CS) was used as a positive comparator for in vitro and in vivo studies. RESULTS Type II collagen gene upregulation and protein secretion was maintained up to 8 days in seeded HOI. In vivo analysis revealed improvement in all scaffold treatment groups. For the first time, electromechanical properties of a cellular-based scaffold were analyzed in a preclinical study. Cell addition did not enhance OAS but improved histological and QP scores in HOI groups. CONCLUSIONS HOI material is biocompatible for up to 8 days in vitro and is supportive of cartilage formation at 6 months in vivo. Electromechanical measurement offers a reliable quality assessment of repaired cartilage.
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Affiliation(s)
- Justinas Maciulaitis
- Institute of Sports, Lithuanian
University of Health Sciences, Kaunas, Lithuania,Justinas Maciulaitis, Institute of Sports,
Lithuanian University of Health Sciences, Tilzes st. 18, 9 House, Kaunas 47181,
Lithuania.
| | - Milda Miskiniene
- Laboratory of Immunology, National
Institute of Cancer, Vilnius, Lithuania
| | - Sima Rekštytė
- Laser Research Center, Faculty of
Physics, Vilnius University, Vilnius, Lithuania
| | - Maksim Bratchikov
- Department of Physiology, Biochemistry,
Microbiology and Laboratory Medicine, Institute of Biomedical Sciences, Faculty of
Medicine, Vilnius University, Vilnius, Lithuania
| | - Adas Darinskas
- Laboratory of Immunology, National
Institute of Cancer, Vilnius, Lithuania
| | - Agne Simbelyte
- National Center of Pathology, Affiliate
of Vilnius University Hospital Santaros Klinikos, Vilnius, Lithuania
| | - Gintaras Daunoras
- Non-infectious Disease Department,
Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Aida Laurinaviciene
- National Center of Pathology, Affiliate
of Vilnius University Hospital Santaros Klinikos, Vilnius, Lithuania
| | - Arvydas Laurinavicius
- National Center of Pathology, Affiliate
of Vilnius University Hospital Santaros Klinikos, Vilnius, Lithuania
| | - Rimtautas Gudas
- Institute of Sports, Lithuanian
University of Health Sciences, Kaunas, Lithuania
| | | | - Romaldas Maciulaitis
- Institute of Physiology and
Pharmacology, Medical Academy, Lithuanian University of Health Sciences, Kaunas,
Lithuania
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3
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Poillot P, Le Maitre CL, Huyghe JM. The strain-generated electrical potential in cartilaginous tissues: a role for piezoelectricity. Biophys Rev 2021; 13:91-100. [PMID: 33747246 PMCID: PMC7930161 DOI: 10.1007/s12551-021-00779-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 01/01/2021] [Indexed: 12/26/2022] Open
Abstract
The strain-generated potential (SGP) is a well-established mechanism in cartilaginous tissues whereby mechanical forces generate electrical potentials. In articular cartilage (AC) and the intervertebral disc (IVD), studies on the SGP have focused on fluid- and ionic-driven effects, namely Donnan, diffusion and streaming potentials. However, recent evidence has indicated a direct coupling between strain and electrical potential. Piezoelectricity is one such mechanism whereby deformation of most biological structures, like collagen, can directly generate an electrical potential. In this review, the SGP in AC and the IVD will be revisited in light of piezoelectricity and mechanotransduction. While the evidence base for physiologically significant piezoelectric responses in tissue is lacking, difficulties in quantifying the physiological response and imperfect measurement techniques may have underestimated the property. Hindering our understanding of the SGP further, numerical models to-date have negated ferroelectric effects in the SGP and have utilised classic Donnan theory that, as evidence argues, may be oversimplified. Moreover, changes in the SGP with degeneration due to an altered extracellular matrix (ECM) indicate that the significance of ionic-driven mechanisms may diminish relative to the piezoelectric response. The SGP, and these mechanisms behind it, are finally discussed in relation to the cell response.
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Affiliation(s)
- Philip Poillot
- Bernal Institute, University of Limerick, Limerick, Ireland
| | | | - Jacques M. Huyghe
- Bernal Institute, University of Limerick, Limerick, Ireland
- Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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4
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Patel JM, Wise BC, Bonnevie ED, Mauck RL. A Systematic Review and Guide to Mechanical Testing for Articular Cartilage Tissue Engineering. Tissue Eng Part C Methods 2019; 25:593-608. [PMID: 31288616 DOI: 10.1089/ten.tec.2019.0116] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Articular cartilage is integral to the mechanical function of many joints in the body. When injured, cartilage lacks the capacity to self-heal, and thus, therapies and replacements have been developed in recent decades to treat damaged cartilage. Given that the primary function of articular cartilage is mechanical in nature, rigorous physical evaluation of cartilage tissues undergoing treatment and cartilage constructs intended for replacement is an absolute necessity. With the large number of groups developing cartilage tissue engineering strategies, however, a variety of mechanical testing protocols have been reported in the literature. This lack of consensus in testing methods makes comparison between studies difficult at times, and can lead to misinterpretation of data relative to native tissue. Therefore, the purpose of this study was to systematically review mechanical testing of articular cartilage and cartilage repair constructs over the past 10 years (January 2009-December 2018), to highlight the most common testing configurations, and to identify key testing parameters. For the most common tests, key parameters identified in this systematic review were validated by characterizing both cartilage tissue and hydrogels commonly used in cartilage tissue engineering. Our findings show that compression testing was the most common test performed (80.2%; 158/197), followed by evaluation of frictional properties (18.8%; 37/197). Upon further review of those studies performing compression testing, the various modes (ramp, stress relaxation, creep, dynamic) and testing configurations (unconfined, confined, in situ) are described and systematically reviewed for parameters, including strain rate, equilibrium time, and maximum strain. This systematic analysis revealed considerable variability in testing methods. Our validation testing studies showed that such variations in testing criteria could have large implications on reported outcome parameters (e.g., modulus) and the interpretation of findings from these studies. This analysis is carried out for all common testing methods, followed by a discussion of less common trends and directions in the mechanical evaluation of cartilage tissues and constructs. Overall, this work may serve as a guide for cartilage tissue engineers seeking to rigorously evaluate the physical properties of their novel treatment strategies. Impact Statement Articular cartilage tissue engineering has made significant strides with regard to treatments and replacements for injured tissue. The evaluation of these approaches typically involves mechanical testing, yet the plethora of testing techniques makes comparisons between studies difficult, and often leads to misinterpretation of data compared with native tissue. This study serves as a guide for the mechanical testing of cartilage tissues and constructs, highlighting recent trends in test conditions and validating these common procedures. Cartilage tissue engineers, especially those unfamiliar with mechanical testing protocols, will benefit from this study in their quest to physically evaluate novel treatment and regeneration approaches.
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Affiliation(s)
- Jay M Patel
- McKay Orthopedic Research Laboratory, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Translational Musculoskeletal Research Center, Corporal Michael J Crescenz VA Medical Center, Philadelphia, Pennsylvania
| | - Brian C Wise
- McKay Orthopedic Research Laboratory, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Edward D Bonnevie
- McKay Orthopedic Research Laboratory, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Translational Musculoskeletal Research Center, Corporal Michael J Crescenz VA Medical Center, Philadelphia, Pennsylvania
| | - Robert L Mauck
- McKay Orthopedic Research Laboratory, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Translational Musculoskeletal Research Center, Corporal Michael J Crescenz VA Medical Center, Philadelphia, Pennsylvania.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
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5
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Farooqi AR, Bader R, van Rienen U. Numerical Study on Electromechanics in Cartilage Tissue with Respect to Its Electrical Properties. TISSUE ENGINEERING PART B-REVIEWS 2018; 25:152-166. [PMID: 30351244 PMCID: PMC6486674 DOI: 10.1089/ten.teb.2018.0214] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hyaline cartilage undergoes many substantial age-related physiochemical and biomechanical changes that reduce its ability to overcome the effects of mechanical stress and injury. In quest of therapeutic options, magnetic stimulation and electrical stimulation (ES) have been proposed for improving tissue engineering approaches for the repair of articular cartilage. The aim of this study is to summarize in silico investigations involving induced electrical properties of cartilage tissue due to various biophysical stimuli along their respective mathematical descriptions. Based on these, a preliminary numerical study involving electromechanical transduction in bovine cartilage tissue has been carried out using an open source finite element computational software. The simulation results have been compared to experimental results from the literature. This study serves as a basis for further in silico studies to better understand the behavior of hyaline cartilage tissue due to ES and to find an optimal stimulation protocol for the cartilage regeneration. Moreover, it provides an overview of the basic models along with mathematical description and scope for future research regarding electrical behavior of the cartilage tissue using open source software.
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Affiliation(s)
- Abdul Razzaq Farooqi
- 1 Institute of General Electrical Engineering, Faculty of Computer Science and Electrical Engineering, University of Rostock, Rostock, Germany
| | - Rainer Bader
- 2 Research Laboratory for Biomechanics and Implant Technology, Department of Orthopedics, Rostock University Medical Center, University Medicine Rostock, Rostock, Germany.,3 Department Life, Light & Matter, University of Rostock, Rostock, Germany
| | - Ursula van Rienen
- 1 Institute of General Electrical Engineering, Faculty of Computer Science and Electrical Engineering, University of Rostock, Rostock, Germany.,3 Department Life, Light & Matter, University of Rostock, Rostock, Germany
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6
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Kotelsky A, Woo CW, Delgadillo LF, Richards MS, Buckley MR. An Alternative Method to Characterize the Quasi-Static, Nonlinear Material Properties of Murine Articular Cartilage. J Biomech Eng 2018; 140:2657496. [PMID: 29049670 DOI: 10.1115/1.4038147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Indexed: 11/08/2022]
Abstract
With the onset and progression of osteoarthritis (OA), articular cartilage (AC) mechanical properties are altered. These alterations can serve as an objective measure of tissue degradation. Although the mouse is a common and useful animal model for studying OA, it is extremely challenging to measure the mechanical properties of murine AC due to its small size (thickness < 50 μm). In this study, we developed novel and direct approach to independently quantify two quasi-static mechanical properties of mouse AC: the load-dependent (nonlinear) solid matrix Young's modulus (E) and drained Poisson's ratio (ν). The technique involves confocal microscope-based multiaxial strain mapping of compressed, intact murine AC followed by inverse finite element analysis (iFEA) to determine E and ν. Importantly, this approach yields estimates of E and ν that are independent of the initial guesses used for iterative optimization. As a proof of concept, mechanical properties of AC on the medial femoral condyles of wild-type mice were obtained for both trypsin-treated and control specimens. After proteolytic tissue degradation induced through trypsin treatment, a dramatic decrease in E was observed (compared to controls) at each of the three tested loading conditions. A significant decrease in ν due to trypsin digestion was also detected. These data indicate that the method developed in this study may serve as a valuable tool for comparative studies evaluating factors involved in OA pathogenesis using experimentally induced mouse OA models.
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Affiliation(s)
- Alexander Kotelsky
- Department of Biomedical Engineering, University of Rochester, 207 Goergen Hall, Box 270168, Rochester, NY 14627 e-mail:
| | - Chandler W Woo
- Department of Biomedical Engineering, University of Rochester, 207 Goergen Hall, Box 270168, Rochester, NY 14627 e-mail:
| | - Luis F Delgadillo
- Department of Biomedical Engineering, University of Rochester, 207 Goergen Hall, Box 270168, Rochester, NY 14627 e-mail:
| | - Michael S Richards
- Department of Surgery, School of Medicine and Dentistry, University of Rochester Medical Center, 601 Elmwood Avenue, Rm 2.4153, Rochester, NY 14627 e-mail:
| | - Mark R Buckley
- Department of Biomedical Engineering, University of Rochester, 207 Goergen Hall, Box 270168, Rochester, NY 14627 e-mail:
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7
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Zhu L, Garon M, Quenneville É, Buschmann MD, Savard P. Electrical potentials measured on the surface of the knee reflect the changes of the contact force in the knee joint produced by postural sway. Gait Posture 2017; 52:159-164. [PMID: 27914310 DOI: 10.1016/j.gaitpost.2016.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 09/02/2016] [Accepted: 10/17/2016] [Indexed: 02/02/2023]
Abstract
Electroarthrography (EAG) is a novel technique for recording potentials on the knee surface that are generated by the compression of articular cartilage and that reflect both compression force and cartilage quality. The mechanical loading of the knee is achieved by transferring the subject's body weight from a bipedal stance to a unipedal stance. We hypothesized that EAG potentials change with postural sway. The study was performed on 20 normal subjects (10 male, 10 female; age 29±10.5 yrs.; mass 68.8±14.2kg; height 172.6±11.4cm). Data was recorded during 10 successive loading cycles repeated on two different days. During loading, EAG potentials were recorded with 4 electrodes placed on both sides of the knee and the ground reaction force (GRF) and the antero-posterior and medial-lateral displacements of the center of pressure (COP) were measured with a force plate. Two electromechanical models predicting the EAG signal from the GRF alone or from the GRF plus the COP displacements were computed by linear regression. The mean relative error between the four EAG signals and the predicted signals ranged from 24% to 49% for the GRF model, and from 15% to 35% for the GRF+COP model, this reduction was statistically significant at 3 electrode sites (p<0.05). The GRF+COP model also improved the repeatability of the parameters estimated on the first and second days when compared to the GRF model. In conclusion, EAG signals can be predicted by GRF and COP displacements and may reflect changes in the knee contact force due to postural sway.
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Affiliation(s)
- Lin Zhu
- Institut de Génie Biomédical, Polytechnique Montréal, Montréal, Québec, Canada
| | | | | | - Michael D Buschmann
- Institut de Génie Biomédical, Polytechnique Montréal, Montréal, Québec, Canada
| | - Pierre Savard
- Institut de Génie Biomédical, Polytechnique Montréal, Montréal, Québec, Canada.
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8
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Manzano S, Doblaré M, Doweidar MH. Parameter-dependent behavior of articular cartilage: 3D mechano-electrochemical computational model. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2015; 122:491-502. [PMID: 26506530 DOI: 10.1016/j.cmpb.2015.09.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/02/2015] [Accepted: 09/23/2015] [Indexed: 06/05/2023]
Abstract
BACKGROUND AND OBJECTIVE Changes in mechano-electrochemical properties of articular cartilage play an essential role in the majority of cartilage diseases. Despite of this importance, the specific effect of each parameter into tissue behavior remains still obscure. Parametric computational modeling of cartilage can provide some insights into this matter, specifically the study of mechano-electrochemical properties variation and their correlation with tissue swelling, water and ion fluxes. Thus, the aim of this study is to evaluate the influence of the main mechanical and electrochemical parameters on the determination of articular cartilage behavior by a parametric analysis through a 3D finite element model. METHODS For this purpose, a previous 3D mechano-electrochemical model, developed by the same authors, of articular cartilage behavior has been used. Young's modulus, Poisson coefficient, ion diffusivities and ion activity coefficients variations have been analyzed and quantified through monitoring tissue simulated response. RESULTS Simulation results show how Young's modulus and Poisson coefficient control tissue behavior rather than electrochemical properties. Meanwhile, ion diffusivity and ion activity coefficients appear to be vital in controlling velocity of incoming and outgoing fluxes. CONCLUSIONS This parametric study establishes a basic guide when defining the main properties that are essential to be included into computational modeling of articular cartilage providing a helpful tool in tissue simulations.
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Affiliation(s)
- Sara Manzano
- Group of Structural Mechanics and Materials Modelling (GEMM), Aragón Institute of Engineering Research (I3A), University of Zaragoza, Spain; Mechanical Engineering Department, School of Engineering and Architecture (EINA), University of Zaragoza, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Spain
| | - Manuel Doblaré
- Group of Structural Mechanics and Materials Modelling (GEMM), Aragón Institute of Engineering Research (I3A), University of Zaragoza, Spain; Mechanical Engineering Department, School of Engineering and Architecture (EINA), University of Zaragoza, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Spain
| | - Mohamed Hamdy Doweidar
- Group of Structural Mechanics and Materials Modelling (GEMM), Aragón Institute of Engineering Research (I3A), University of Zaragoza, Spain; Mechanical Engineering Department, School of Engineering and Architecture (EINA), University of Zaragoza, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Spain.
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9
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Abstract
Articular cartilage is a unique load-bearing connective tissue with a low intrinsic capacity for repair and regeneration. Its avascularity makes it relatively hypoxic and its unique extracellular matrix is enriched with cations, which increases the interstitial fluid osmolarity. Several physicochemical and biomechanical stimuli are reported to influence chondrocyte metabolism and may be utilized for regenerative medical approaches. In this review article, we summarize the most relevant stimuli and describe how ion channels may contribute to cartilage homeostasis, with special emphasis on intracellular signaling pathways. We specifically focus on the role of calcium signaling as an essential mechanotransduction component and highlight the role of phosphatase signaling in this context.
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Affiliation(s)
- Holger Jahr
- Department of Orthopaedic Surgery, University Hospital RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany
- The D-BOARD European Consortium for Biomarker Discovery, Surrey, UK
| | - Csaba Matta
- The D-BOARD European Consortium for Biomarker Discovery, Surrey, UK
- Department of Veterinary Preclinical Sciences, School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Duke of Kent Building, Guildford, Surrey GU2 7XH UK
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, Debrecen, 4032 Hungary
| | - Ali Mobasheri
- The D-BOARD European Consortium for Biomarker Discovery, Surrey, UK
- Department of Veterinary Preclinical Sciences, School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Duke of Kent Building, Guildford, Surrey GU2 7XH UK
- Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, Arthritis Research UK Pain Centre, Medical Research Council and Arthritis Research UK Centre for Musculoskeletal Ageing Research, University of Nottingham, Queen’s Medical Centre, Nottingham, NG7 2UH UK
- Center of Excellence in Genomic Medicine Research (CEGMR), King Fahd Medical Research Center (KFMRC), King AbdulAziz University, Jeddah, 21589 Kingdom of Saudi Arabia
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10
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Brady MA, Waldman SD, Ethier CR. The Application of Multiple Biophysical Cues to Engineer Functional Neocartilage for Treatment of Osteoarthritis. Part I: Cellular Response. TISSUE ENGINEERING PART B-REVIEWS 2015; 21:1-19. [DOI: 10.1089/ten.teb.2013.0757] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Mariea A. Brady
- Department of Bioengineering, Imperial College London, South Kensington, London, United Kingdom
| | | | - C. Ross Ethier
- Department of Bioengineering, Imperial College London, South Kensington, London, United Kingdom
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia
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11
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Han Q, Buschmann MD, Savard P. The forward problem of electroarthrography: modeling load-induced electrical potentials at the surface of the knee. IEEE Trans Biomed Eng 2014; 61:2020-7. [PMID: 24956620 DOI: 10.1109/tbme.2014.2312104] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Electroarthrography (EAG) is a novel technology recently proposed to detect cartilage degradation. EAG consists of recording electrical potentials on the knee surface while the joint is undergoing compressive loading. Previous results show that these signals originating from streaming potentials in the cartilage reflect joint cartilage health. The aim of this study is to contribute to the understanding of the generation of the EAG signals and to the development of interpretation criteria using computer models of the human knee. The knee is modeled as a volume conductor composed of different regions characterized by specific electrical conductivities. The source of the EAG signal is the load-induced interstitial fluid flow that transports ions within the compressed cartilage. It is modeled as an impressed current density in different sections of the articular cartilage. The finite-element method is used to compute the potential distribution in two knee models with a realistic geometry. The simulated potential distributions correlate very well with previously measured potential values, which further supports the hypothesis that the EAG signals originate from compressed cartilage. Also, different localized cartilage defects simulated as a reduced impressed current density produce specific potential distributions that may be used to detect and localize cartilage degradation. In conclusion, given the structural and electrophysiological complexity of the knee, computer modeling constitutes an important tool to improve our understanding of the generation of EAG signals and of the various factors that affect the EAG signals so as to help develop the EAG technology as a useful clinical tool.
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12
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Krase A, Abedian R, Steck E, Hurschler C, Richter W. BMP activation and Wnt-signalling affect biochemistry and functional biomechanical properties of cartilage tissue engineering constructs. Osteoarthritis Cartilage 2014; 22:284-92. [PMID: 24280245 DOI: 10.1016/j.joca.2013.11.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 10/26/2013] [Accepted: 11/15/2013] [Indexed: 02/02/2023]
Abstract
OBJECTIVES Bone morphogenetic protein (BMP-) and Wnt-signalling play crucial roles in cartilage homeostasis. Our objective was to investigate whether activation of the BMP-pathway or stimulation of Wnt-signalling cascades effectively enhances cartilage-specific extracellular matrix (ECM) accumulation and functional biomechanical parameters of chondrocyte-seeded tissue engineering (TE)-constructs. DESIGN Articular chondrocytes were cultured in collagen-type-I/III-matrices over 6 weeks to create a biomechanical standard curve. Effects of stimulation with 100 ng/mL BMP-4/-7 heterodimer or 10 mM lithium chloride (LiCl) on ECM-deposition was quantified and characterized histologically. Biomechanical parameters were determined by the Very Low Rubber Hardness (VLRH) method and under confined compression stress relaxation. RESULTS BMP-4/-7 treatment resulted in stronger collagen type-II staining and significantly enhanced glycosaminoglycan (GAG) deposition (3.2-fold; *P < 0.01) correlating with improved hardness (∼1.7-fold; *P = 0.001) reaching 83% of native cartilage values after 28 days, a value not reached before 9 weeks without stimulation. LiCl treatment enhanced VLRH slightly, but significantly (∼1.3-fold; *P = 0.016) with a trend to more ECM-deposition. BMP-4/-7 treatment significantly enhanced the E Modulus (105.7 ± 34.1 kPa; *P = 0.000001) compared to controls (8.0 ± 4.2 kPa). Poisson's ratio was significantly improved by BMP-4/-7 treatment (0.0703 ± 0.0409; *P = 0.013) vs controls (0.0432 ± 0.0284) and a significantly lower permeability (5.8 ± 2.1056 × 10(-14) m4/N.s; *P = 0.00001) was detected compared to untreated scaffolds (4.4 ± 3.1289 × 10(-13) m4/N.s). CONCLUSIONS While Wnt-activation is less effective, BMP-4/-7 heterodimer stimulation approximated native cartilage features in less than 50% of standard culture time representing a promising strategy for functional cartilage TE to improve biomechanical parameters of engineered cartilage.
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Affiliation(s)
- A Krase
- Research Center for Experimental Orthopaedics, Department of Orthopaedics, Trauma Surgery and Paraplegiology, Heidelberg University Hospital, Heidelberg, Germany.
| | - R Abedian
- Laboratory for Biomechanics and Biomaterials, Orthopaedic Department, Hannover Medical School of Hannover, Hannover, Germany.
| | - E Steck
- Research Center for Experimental Orthopaedics, Department of Orthopaedics, Trauma Surgery and Paraplegiology, Heidelberg University Hospital, Heidelberg, Germany.
| | - C Hurschler
- Laboratory for Biomechanics and Biomaterials, Orthopaedic Department, Hannover Medical School of Hannover, Hannover, Germany.
| | - W Richter
- Research Center for Experimental Orthopaedics, Department of Orthopaedics, Trauma Surgery and Paraplegiology, Heidelberg University Hospital, Heidelberg, Germany.
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Préville AM, Lavigne P, Buschmann MD, Hardin J, Han Q, Djerroud L, Savard P. Electroarthrography: a novel method to assess articular cartilage and diagnose osteoarthritis by non-invasive measurement of load-induced electrical potentials at the surface of the knee. Osteoarthritis Cartilage 2013; 21:1731-7. [PMID: 23850553 DOI: 10.1016/j.joca.2013.07.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 06/05/2013] [Accepted: 07/01/2013] [Indexed: 02/02/2023]
Abstract
OBJECTIVE A new technique called electroarthrography (EAG) measures electrical potentials on the surface of the knee during joint loading. The objective of this study was to evaluate the effectiveness of EAG to assess joint cartilage degeneration. DESIGN EAG recordings were performed on 20 asymptomatic subjects (Control group) and on 20 patients with bilateral knee osteoarthritis (OA) who had had a unilateral total knee replacement (TKR), both the TKR knee and the remaining knee were analyzed. EAG signals were recorded at eight electrode sites over one knee as the subjects shifted their weight from one leg to the other to achieve joint loading. The EAG signals were filtered, baseline-corrected and time-averaged. RESULTS EAG repeatability was assessed with a test-retest protocol which showed statistically significant high intraclass correlation coefficients (ICC) for four electrode sites near the joint line. These sites also showed the highest mean EAG values. The mean EAG potentials of the Control group were significantly higher compared with the OA group for three sites overlying the joint line. The potentials overlying the TKR were statistically nul. In the Control group, no statistically significant correlation was found between the EAG amplitude and age, weight, height or body mass index (BMI); no statistical difference was found in mean EAG potentials between women and men. CONCLUSIONS This study indicates that EAG signals arise from the streaming potentials in compressed articular cartilage which are known sensitive indicators of joint cartilage health. EAG is a promising new technique for the non-invasive assessment of cartilage degeneration and arthritis.
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Affiliation(s)
- A-M Préville
- Institut de génie biomédical, École Polytechnique de Montréal, Montréal, Québec, Canada H3C 3A7.
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14
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Ko LS, Quinn TM. Matrix fixed charge density modulates exudate concentration during cartilage compression. Biophys J 2013; 104:943-50. [PMID: 23442973 DOI: 10.1016/j.bpj.2012.12.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 12/06/2012] [Accepted: 12/17/2012] [Indexed: 10/27/2022] Open
Abstract
Electrolyte filtration arises due to the presence of fixed charges in cartilage extracellular matrix glycosaminoglycans (GAGs). Commonly assumed negligible, it can be important for design and interpretation of streaming potential measurements and modeling assumptions. To quantify the scale of this phenomenon, chloride ion concentration in exudate of compressed cartilage was measured by Mohr's titration and explant GAG content was colorimetrically assayed. Pilot studies indicated that an appropriate strain rate for experiments was 8 × 10(-3) s(-1) to eliminate concerns of exudate evaporation and explant damage (at low and high strain rates, respectively). Exudate chloride concentration of explants equilibrated in 1× PBS was significantly (p < 0.05) lower than the bath chloride concentration at strains of 37.5, 50, and 62.5%, with clear dependence on strain magnitude. Exudate chloride concentration was also significantly lower than that of the bath when 50% strain was applied after equilibration in 0.5, 1, and 2× PBS, with a trend for an increase in this relative difference with decreasing bath concentration (p = 0.065 between 0.5 and 2× PBS). Decreasing exudate chloride concentration correlated negatively with increasing postcompression GAG concentration. No difference between exudate chloride concentration and bath chloride concentration was ever observed for compression of uncharged agarose gel controls. Findings show that exudate from compressed cartilage is dilute relative to the bath due to the presence of matrix fixed charges, and this difference can generate diffusion potentials external to the explant, which may affect streaming potential measurements particularly under conditions of low strain rates and high strains.
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Affiliation(s)
- Lok Shun Ko
- Department of Chemical Engineering, McGill University, Montreal, Quebec, Canada
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15
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Abedian R, Willbold E, Becher C, Hurschler C. In vitro electro-mechanical characterization of human knee articular cartilage of different degeneration levels: a comparison with ICRS and Mankin scores. J Biomech 2013; 46:1328-34. [PMID: 23477790 DOI: 10.1016/j.jbiomech.2013.02.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 01/10/2013] [Accepted: 02/05/2013] [Indexed: 11/27/2022]
Abstract
In the present study, the electro-mechanical properties of human knee articular cartilage were measured in vitro. An arthroscopic measurement tool was used to measure streaming potential integral (SPI), after which creep indentation tests were performed. Additionally, degradation level of the tissue was determined in accordance with the International Cartilage Repair Society (ICRS score), and hematoxylin/eosin and safranin O staining were performed to determine the Mankin score. Mechanical test results were evaluated both analytically and by means of a finite-element-optimized parameter identification procedure. The SPI was then correlated with poroelastic E modulus (r=0.563, p<0.008, n=22), natural logarithm of hydraulic permeability (r=0.374, p<0.095, n=22) and cartilage degeneration scores (ICRS and Mankin) (r=-0.749, p<0.000, n=22 and r=-0.409, p<0.059, n=22 respectively).
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Affiliation(s)
- Reza Abedian
- Laboratory for Biomechanics and Biomaterials, Department of Orthopaedic Surgery, Hannover Medical School, Germany.
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16
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Han E, Ge C, Chen AC, Schumacher BL, Sah RL. Compaction enhances extracellular matrix content and mechanical properties of tissue-engineered cartilaginous constructs. Tissue Eng Part A 2012; 18:1151-60. [PMID: 22372815 PMCID: PMC3360506 DOI: 10.1089/ten.tea.2011.0300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 01/27/2012] [Indexed: 11/13/2022] Open
Abstract
Many cell-based tissue-engineered cartilaginous constructs are mechanically softer than native tissue and have low content and abnormal proportions of extracellular matrix (ECM) constituents. We hypothesized that the load-bearing mechanical properties of cartilaginous constructs improve with the inclusion of collagen (COL) and proteoglycan (PG) during assembly. The objectives of this work were to determine (1) the effect of addition of PG, COL, or COL+PG on compressive properties of 2% agarose constructs and (2) the ability of mechanical compaction to concentrate matrix content and improve the compressive properties of such constructs. The inclusion of COL+PG improved the compressive properties of hydrogel constructs compared with PG or COL alone. Mechanical compaction increased the PG and COL concentrations in and compressive stiffness of the constructs. Chondrocytes included in the constructs maintained high viability after compaction. These results support the concepts that the assembly of cartilaginous constructs with COL+PG and application of mechanical compaction enhance the ECM content and compressive properties of engineered cartilaginous constructs.
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Affiliation(s)
- EunHee Han
- Department of Bioengineering, University of California-San Diego, La Jolla, California
| | - Chenghao Ge
- Department of Bioengineering, University of California-San Diego, La Jolla, California
| | - Albert C. Chen
- Department of Bioengineering, University of California-San Diego, La Jolla, California
| | - Barbara L. Schumacher
- Department of Bioengineering, University of California-San Diego, La Jolla, California
| | - Robert L. Sah
- Department of Bioengineering, University of California-San Diego, La Jolla, California
- Center for Musculoskeletal Research, Institute of Engineering in Medicine, University of California-San Diego, La Jolla, California
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17
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A feasibility study for evaluation of mechanical properties of articular cartilage with a two-electrode electrical impedance method. J Orthop Sci 2012; 17:272-80. [PMID: 22427018 DOI: 10.1007/s00776-012-0208-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 02/21/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND Since articular cartilage has important mechanical properties such as load-bearing, shock absorption and lubrication for activities in daily life, it is important to evaluate the mechanical properties of repaired cartilage in terms of whether those properties are the same as those of natural cartilage. The purpose of this study was to investigate the effectiveness of an electrical impedance method for quantitatively measuring the mechanical properties of cartilage. METHODS Cartilage specimens were harvested from porcine knee joint, and two kinds of enzyme-treated cartilages were prepared to investigate the correlation between mechanical and electrical properties resulting from changes in the structure of the extracellular matrix. Collagenase solution and hyaluronidase solution were used to digest the collagen fibril and proteoglycan, respectively. Electrical impedance measurement, indentation test and biochemical analysis were carried out for the enzyme-treated cartilages. RESULTS The water content increased with enzyme treatment time, and the permeability of the treated cartilages increased with decreasing glycosaminoglycan content for both types of enzyme-treated cartilages. The aggregate modulus and the electrical resistivity for both types of enzyme-treated cartilages decreased with increasing permeability after 12-h treatment. The aggregate modulus and the electrical resistivity for both types of treated cartilages decreased with increasing water content and permeability after 24-h treatment. The electrical resistivity and the aggregate modulus of articular cartilage depended not only on the water content, but also on the permeability, and the electrical resistivity for both types of enzyme-treated cartilages was found to be significantly linearly correlated with the aggregate modulus. CONCLUSIONS These results showed that the aggregate modulus of articular cartilage can be estimated by measuring its electrical impedance.
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Chandran PL, Horkay F. Aggrecan, an unusual polyelectrolyte: review of solution behavior and physiological implications. Acta Biomater 2012; 8:3-12. [PMID: 21884828 DOI: 10.1016/j.actbio.2011.08.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 08/03/2011] [Accepted: 08/11/2011] [Indexed: 10/17/2022]
Abstract
Aggrecan is a high-molecular-weight, bottlebrush-shaped, negatively charged biopolymer that forms supermolecular complexes with hyaluronic acid. In the extracellular matrix of cartilage, aggrecan-hyaluronic acid complexes are interspersed in a collagen meshwork and provide the osmotic properties required to resist deswelling under compressive load. In this review we compile aggrecan solution behavior from different experimental techniques, and discuss them in the context of concentration regimes that were identified in osmotic pressure experiments. At low concentrations, aggrecan exhibits microgel-like behavior. With increasing concentration, the bottlebrushes self-assemble into large complexes. In the physiological concentration range (2<c(aggrecan)<8% w/w), the physical properties of the solution are dominated by repulsive electrostatic interactions between aggrecan complexes. We discuss the consequences of the bottlebrush architecture on the polyelectrolyte characteristics of the aggrecan molecule, and its implications for cartilage properties and function.
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19
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Changoor A, Coutu JP, Garon M, Quenneville E, Hurtig MB, Buschmann MD. Streaming potential-based arthroscopic device is sensitive to cartilage changes immediately post-impact in an equine cartilage injury model. J Biomech Eng 2011; 133:061005. [PMID: 21744925 DOI: 10.1115/1.4004230] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Models of post-traumatic osteoarthritis where early degenerative changes can be monitored are valuable for assessing potential therapeutic strategies. Current methods for evaluating cartilage mechanical properties may not capture the low-grade cartilage changes expected at these earlier time points following injury. In this study, an explant model of cartilage injury was used to determine whether streaming potential measurements by manual indentation could detect cartilage changes immediately following mechanical impact and to compare their sensitivity to biomechanical tests. Impacts were delivered ex vivo, at one of three stress levels, to specific positions on isolated adult equine trochlea. Cartilage properties were assessed by streaming potential measurements, made pre- and post-impact using a commercially available arthroscopic device, and by stress relaxation tests in unconfined compression geometry of isolated cartilage disks, providing the streaming potential integral (SPI), fibril modulus (Ef), matrix modulus (Em), and permeability (k). Histological sections were stained with Safranin-O and adjacent unstained sections examined in polarized light microscopy. Impacts were low, 17.3 ± 2.7 MPa (n = 15), medium, 27.8 ± 8.5 MPa (n = 13), or high, 48.7 ± 12.1 MPa (n = 16), and delivered using a custom-built spring-loaded device with a rise time of approximately 1 ms. SPI was significantly reduced after medium (p = 0.006) and high (p<0.001) impacts. Ef, representing collagen network stiffness, was significantly reduced in high impact samples only (p < 0.001 lateral trochlea, p = 0.042 medial trochlea), where permeability also increased (p = 0.003 lateral trochlea, p = 0.007 medial trochlea). Significant (p < 0.05, n = 68) moderate to strong correlations between SPI and Ef (r = 0.857), Em (r = 0.493), log(k) (r = -0.484), and cartilage thickness (r = -0.804) were detected. Effect sizes were higher for SPI than Ef, Em, and k, indicating greater sensitivity of electromechanical measurements to impact injury compared to purely biomechanical parameters. Histological changes due to impact were limited to the presence of superficial zone damage which increased with impact stress. Non-destructive streaming potential measurements were more sensitive to impact-related articular cartilage changes than biomechanical assessment of isolated samples using stress relaxation tests in unconfined compression geometry. Correlations between electromechanical and biomechanical methods further support the relationship between non-destructive electromechanical measurements and intrinsic cartilage properties.
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Affiliation(s)
- A Changoor
- Department of Chemical Engineering, Institute of Biomedical Engineering, École Polytechnique de Montréal, P.O. Box 6079, Station Centre-Ville Montreal, QC H3C3A7, Canada
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20
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Relationship between streaming potential and compressive stress in bovine intervertebral tissue. J Biomech 2011; 44:2477-81. [PMID: 21763660 DOI: 10.1016/j.jbiomech.2011.06.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2010] [Revised: 06/14/2011] [Accepted: 06/15/2011] [Indexed: 11/21/2022]
Abstract
The intervertebral disc is formed by the nucleus pulposus (NP) and annulus fibrosus (AF), and intervertebral tissue contains a large amount of negatively charged proteoglycan. When this tissue becomes deformed, a streaming potential is induced by liquid flow with positive ions. The anisotropic property of the AF tissue is caused by the structural anisotropy of the solid phase and the liquid phase flowing into the tissue with the streaming potential. This study investigated the relationship between the streaming potential and applied stress in bovine intervertebral tissue while focusing on the anisotropy and loading location. Column-shaped specimens, 5.5 mm in diameter and 3 mm thick, were prepared from the tissue of the AF, NP and the annulus-nucleus transition region (AN). The loading direction of each specimen was oriented in the spinal axial direction, as well as in the circumferential and radial directions of the spine considering the anisotropic properties of the AF tissue. The streaming potential changed linearly with stress in all specimens. The linear coefficients k(e) of the relationship between stress and streaming potential depended on the extracted positions. These coefficients were not affected by the anisotropy of the AF tissue. In addition, these coefficients were lower in AF than in NP specimens. Except in the NP specimen, the k(e) values were higher under faster compression rate conditions. In cyclic compression loading the streaming potential changed linearly with compressive stress, regardless of differences in the tissue and load frequency.
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21
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Changoor A, Fereydoonzad L, Yaroshinsky A, Buschmann MD. Effects of Refrigeration and Freezing on the Electromechanical and Biomechanical Properties of Articular Cartilage. J Biomech Eng 2010; 132:064502. [PMID: 20887036 DOI: 10.1115/1.4000991] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In vitro electromechanical and biomechanical testing of articular cartilage provide critical information about the structure and function of this tissue. Difficulties obtaining fresh tissue and lengthy experimental testing procedures often necessitate a storage protocol, which may adversely affect the functional properties of cartilage. The effects of storage at either 4°C for periods of 6 days and 12 days, or during a single freeze-thaw cycle at −20°C were examined in young bovine cartilage. Non-destructive electromechanical measurements and unconfined compression testing on 3 mm diameter disks were used to assess cartilage properties, including the streaming potential integral (SPI), fibril modulus (Ef), matrix modulus (Em), and permeability (k). Cartilage disks were also examined histologically. Compared with controls, significant decreases in SPI (to 32.3±5.5% of control values, p<0.001), Ef (to 3.1±41.3% of control values, p=0.046), Em (to 6.4±8.5% of control values, p<0.0001), and an increase in k (to 2676.7±2562.0% of control values, p=0.004) were observed at day 12 of refrigeration at 4°C, but no significant changes were detected at day 6. A trend toward detecting a decrease in SPI (to 94.2±6.2% of control values, p=0.083) was identified following a single freeze-thaw cycle, but no detectable changes were observed for any biomechanical parameters. All numbers are mean±95% confidence interval. These results indicate that fresh cartilage can be stored in a humid chamber at 4°C for a maximum of 6 days with no detrimental effects to cartilage electromechanical and biomechanical properties, while one freeze-thaw cycle produces minimal deterioration of biomechanical and electromechanical properties. A comparison to literature suggested that particular attention should be paid to the manner in which specimens are thawed after freezing, specifically by minimizing thawing time at higher temperatures.
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Affiliation(s)
- Adele Changoor
- Biomaterials and Cartilage Laboratory, École Polytechnique de Montréal, P. O. Box 6079, Station Centre-ville, Montréal, QC H3C 3A7, Canada
| | - Liah Fereydoonzad
- Biomaterials and Cartilage Laboratory, École Polytechnique de Montréal, P. O. Box 6079, Station Centre-ville, Montréal, QC H3C 3A7, Canada
| | | | - Michael D. Buschmann
- Biomaterials and Cartilage Laboratory, École Polytechnique de Montréal, P. O. Box 6079, Station Centre-ville, Montréal, QC H3C 3A7, Canada
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22
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June RK, Fyhrie DP. Enzymatic digestion of articular cartilage results in viscoelasticity changes that are consistent with polymer dynamics mechanisms. Biomed Eng Online 2009; 8:32. [PMID: 19889234 PMCID: PMC2778644 DOI: 10.1186/1475-925x-8-32] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 11/04/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cartilage degeneration via osteoarthritis affects millions of elderly people worldwide, yet the specific contributions of matrix biopolymers toward cartilage viscoelastic properties remain unknown despite 30 years of research. Polymer dynamics theory may enable such an understanding, and predicts that cartilage stress-relaxation will proceed faster when the average polymer length is shortened. METHODS This study tested whether the predictions of polymer dynamics were consistent with changes in cartilage mechanics caused by enzymatic digestion of specific cartilage extracellular matrix molecules. Bovine calf cartilage explants were cultured overnight before being immersed in type IV collagenase, bacterial hyaluronidase, or control solutions. Stress-relaxation and cyclical loading tests were performed after 0, 1, and 2 days of incubation. RESULTS Stress-relaxation proceeded faster following enzymatic digestion by collagenase and bacterial hyaluronidase after 1 day of incubation (both p < or = 0.01). The storage and loss moduli at frequencies of 1 Hz and above were smaller after 1 day of digestion by collagenase and bacterial hyaluronidase (all p < or = 0.02). CONCLUSION These results demonstrate that enzymatic digestion alters cartilage viscoelastic properties in a manner consistent with polymer dynamics mechanisms. Future studies may expand the use of polymer dynamics as a microstructural model for understanding the contributions of specific matrix molecules toward tissue-level viscoelastic properties.
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Affiliation(s)
- Ronald K June
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, USA.
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23
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Iatridis JC, Furukawa M, Stokes IAF, Gardner-Morse MG, Laible JP. Spatially resolved streaming potentials of human intervertebral disk motion segments under dynamic axial compression. J Biomech Eng 2009; 131:031006. [PMID: 19154065 DOI: 10.1115/1.3005164] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Intervertebral disk degeneration results in alterations in the mechanical, chemical, and electrical properties of the disk tissue. The purpose of this study is to record spatially resolved streaming potential measurements across intervertebral disks exposed to cyclic compressive loading. We hypothesize that the streaming potential profile across the disk will vary with radial position and frequency and is proportional to applied load amplitude, according to the presumed fluid-solid relative velocity and measured glycosaminoglycan content. Needle electrodes were fabricated using a linear array of AgAgCl micro-electrodes and inserted into human motion segments in the midline from anterior to posterior. They were connected to an amplifier to measure electrode potentials relative to the saline bath ground. Motion segments were loaded in axial compression under a preload of 500 N, sinusoidal amplitudes of +/-200 N and +/-400 N, and frequencies of 0.01 Hz, 0.1 Hz, and 1 Hz. Streaming potential data were normalized by applied force amplitude, and also compared with paired experimental measurements of glycosaminoglycans in each disk. Normalized streaming potentials varied significantly with sagittal position and there was a significant location difference at the different frequencies. Normalized streaming potential was largest in the central nucleus region at frequencies of 0.1 Hz and 1.0 Hz with values of approximately 3.5 microVN. Under 0.01 Hz loading, normalized streaming potential was largest in the outer annulus regions with a maximum value of 3.0 microVN. Correlations between streaming potential and glycosaminoglycan content were significant, with R(2) ranging from 0.5 to 0.8. Phasic relationships between applied force and electrical potential did not differ significantly by disk region or frequency, although the largest phase angles were observed at the outermost electrodes. Normalized streaming potentials were associated with glycosaminoglycan content, fluid, and ion transport. Results suggested that at higher frequencies the transport of water and ions in the central nucleus region may be larger, while at lower frequencies there is enhanced transport near the periphery of the annulus. This study provides data that will be helpful to validate multiphasic models of the disk.
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Affiliation(s)
- James C Iatridis
- School of Engineering, Department of Orthopaedics and Rehabilitation, University of Vermont, 33 Colchester Avenue, Burlington, VT 05405, USA.
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24
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Katta J, Stapleton T, Ingham E, Jin ZM, Fisher J. The effect of glycosaminoglycan depletion on the friction and deformation of articular cartilage. Proc Inst Mech Eng H 2008; 222:1-11. [DOI: 10.1243/09544119jeim325] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Glycosaminoglycans (GAGs) have been shown to be responsible for the interstitial fluid pressurization of articular cartilage and hence its compressive stiffness and load-bearing properties. Contradictory evidence has been presented in the literature on the effect of depleting GAGs on the friction properties of articular cartilage. The aim of this study was to investigate the effect of depleting GAGs on the friction and deformation characteristics of articular cartilage under different tribological conditions. A pin-on-plate machine was utilized to measure the coefficient of friction of native and chondroitinase ABC (CaseABC)-treated articular cartilage under two different models: static (4 mm/s start-up velocity) and dynamic (4 mm/s sliding velocity; 4 mm stroke length) under a load of 25 N (0.4 MPa contact stress) and with phosphate-buffered saline as the lubricant. Indentation tests were carried out at 1 N and 2 N loads (0.14 MPa and 0.28 MPa contact stress levels) to study the deformation characteristics of both native and GAG-depleted cartilage samples. CaseABC treatment rendered the cartilage tissue soft owing to the loss of compressive stiff-ness and a sulphated-sugar assay confirmed the loss of GAGs from the cartilage samples. CaseABC treatment significantly increased (by more than 50 per cent) the friction levels in the dynamic model ( p < 0.05) at higher loading times owing to the loss of biphasic lubrication. CaseABC treatment had no effect on friction in the static model in which the cartilage surfaces did not have an opportunity to recover fluid because of static loading unlike the cartilage tissue in the dynamic model, in which translation of the cartilage surfaces was involved, ensuring effective biphasic lubrication. Therefore the depletion of GAGs had a smaller effect on the coefficient of friction for the static model. Indentation tests showed that GAG-depleted cartilage samples had a lower elastic modulus and higher permeability than native tissue. These results corroborate the role of GAGs in the compressive and friction properties of articular cartilage and emphasize the need for developing strategies to control GAG loss from diseased articular cartilage tissue.
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Affiliation(s)
- J Katta
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - T Stapleton
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - E Ingham
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - Z M Jin
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - J Fisher
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
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25
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Willett TL, Whiteside R, Wild PM, Wyss UP, Anastassiades T. Artefacts in the mechanical characterization of porcine articular cartilage due to freezing. Proc Inst Mech Eng H 2006; 219:23-9. [PMID: 15777054 DOI: 10.1243/095441105x9200] [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] [Indexed: 11/18/2022]
Abstract
Many experimental protocols for investigating articular cartilage mechanics have involved the use of a freeze-thaw cycle for storage or tissue manipulation. It was hypothesized that mechanical properties are altered due to freeze-thaw cycling. The aim of this study, therefore, was to examine the possibility of protocol-induced artefacts in the mechanical properties of porcine articular cartilage specimens related specifically to freeze-thaw events. Twenty-eight osteochondral specimens [14 from the femoral condyles (FCs) and 14 from the patella-femoral (PF) groove] were tested in confined compression before and after being frozen at -20°C for 7 days. The fluid-independent and fluid-dependent mechanical properties (aggregate modulus of the solid phase and the half-life of stress relaxation respectively) were determined and compared. The aggregate modulus decreased by 13.5 per cent and 20.1 per cent for the PF and FC regions respectively ( p = 0.002) and the half-life of the stress relaxation at 10 per cent strain decreased by 6.4 per cent and 12.6 per cent for the PF and FC specimens respectively ( p = 0.0341). In conclusion, it has been shown that the protocol used, which involved freezing to -20°C and thawing after 7 days, caused artefacts in the mechanical properties of porcine osteochondral specimens. It is suggested that protocols requiring freezing must be critically reviewed to eliminate such artefacts.
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Affiliation(s)
- T L Willett
- Human Mobility Research Centre, Queen's University, Kingston, Canada.
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26
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Li LP, Herzog W. Electromechanical response of articular cartilage in indentation--considerations on the determination of cartilage properties during arthroscopy. Comput Methods Biomech Biomed Engin 2005; 8:83-91. [PMID: 16154872 DOI: 10.1080/10255840500167895] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A finite element formulation of streaming potentials in articular cartilage was incorporated into a fibril-reinforced model using the commercial software ABAQUS. This model was subsequently used to simulate interactions between an arthroscopic probe and articular cartilage in a knee joint. Fibril reinforcement was found to account for large fluid pressure at considerable strain rates, as has been observed in un-confined compression. Furthermore, specific electromechanical responses were associated with specific changes in tissue properties that occur with cartilage degeneration. For example, the strong strain-rate dependence of the load response was only observed when the collagen network was intact. Therefore, it is possible to use data measured during arthroscopy to evaluate the degree of cartilage degeneration and the source causing changed properties. However, practical problems, such as the difficulty of controlling the speed of the hand-held probe, may greatly reduce the reliability of such evaluations. The fibril-reinforced electromechanical model revealed that high-speed transient responses were associated with the collagen network, and equilibrium response was primarily determined by proteoglycan matrix. The results presented here may be useful in the application of arthroscopic tools for evaluating cartilage degeneration, for the proper interpretation of data, and for the optimization of data collection during arthroscopy.
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Affiliation(s)
- L P Li
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Alta, Canada.
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27
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Sun DD, Guo XE, Likhitpanichkul M, Lai WM, Mow VC. The influence of the fixed negative charges on mechanical and electrical behaviors of articular cartilage under unconfined compression. J Biomech Eng 2004; 126:6-16. [PMID: 15171124 DOI: 10.1115/1.1644562] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Unconfined compression test has been frequently used to study the mechanical behaviors of articular cartilage, both theoretically and experimentally. It has also been used in explant and gel-cell-complex studies in tissue engineering. In biphasic and poroelastic theories, the effect of charges fixed on the proteoglycan macromolecules in articular cartilage is embodied in the apparent compressive Young's modulus and the apparent Poisson's ratio of the tissue, and the fluid pressure is considered to be the portion above the osmotic pressure. In order to understand how proteoglycan fixed charges might affect the mechanical behaviors of articular cartilage, and in order to predict the osmotic pressure and electric fields inside the tissue in this experimental configuration, it is necessary to use a model that explicitly takes into account the charged nature of the tissue and the flow of ions within its porous interstices. In this paper, we used a finite element model based on the triphasic theory to study how fixed charges in the porous-permeable soft tissue can modulate its mechanical and electrochemical responses under a step displacement in unconfined compression. The results from finite element calculations showed that: 1) A charged tissue always supports a larger load than an uncharged tissue of the same intrinsic elastic moduli. 2) The apparent Young's modulus (the ratio of the equilibrium axial stress to the axial strain) is always greater than the intrinsic Young's modulus of an uncharged tissue. 3) The apparent Poisson's ratio (the negative ratio of the lateral strain to the axial strain) is always larger than the intrinsic Poisson's ratio of an uncharged tissue. 4) Load support derives from three sources: intrinsic matrix stiffness, hydraulic pressure and osmotic pressure. Under the unconfined compression, the Donnan osmotic pressure can constitute between 13%-22% of the total load support at equilibrium. 5) During the stress-relaxation process following the initial instant of loading, the diffusion potential (due to the gradient of the fixed charge density and the associated gradient of ion concentrations) and the streaming potential (due to fluid convection) compete against each other. Within the physiological range of material parameters, the polarity of the electric potential depends on both the mechanical properties and the fixed charge density (FCD) of the tissue. For softer tissues, the diffusion effects dominate the electromechanical response, while for stiffer tissues, the streaming potential dominates this response. 6) Fixed charges do not affect the instantaneous strain field relative to the initial equilibrium state. However, there is a sudden increase in the fluid pressure above the initial equilibrium osmotic pressure. These new findings are relevant and necessary for the understanding of cartilage mechanics, cartilage biosynthesis, electromechanical signal transduction by chondrocytes, and tissue engineering.
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Affiliation(s)
- D D Sun
- Orthopaedic Research Laboratory, Department of Biomedical Engineering, Orthopaedic Surgery and Mechanical Engineering, Columbia University, 630 West, 168th Street, BB1412, New York, NY 10032, USA
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28
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Ho KHK, Diaz Valdes SH, Protsenko DE, Aguilar G, Wong BJF. Electromechanical reshaping of septal cartilage. Laryngoscope 2003; 113:1916-21. [PMID: 14603047 DOI: 10.1097/00005537-200311000-00011] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES This study describes the process of tissue electroforming and how shape changes in cartilage can be produced by the application of direct current (DC). The dependence of shape change on voltage and application time is explored. STUDY DESIGN Basic investigation using ex vivo porcine septal cartilage grafts and electromechanical cartilage deformation focused on development of a new surgical technique. METHODS Uniform flat porcine nasal septal cartilage specimens were mechanically deformed between two semicircular aluminum electrodes. DC current was applied to establish charge separation and electrical streaming potential. Voltage (0-3.5 V) and application time (0-5 minutes) were varied. Shape change was measured, and shape retention was calculated using analytic representation. The effect of the direction of applied current on shape change was evaluated by switching the polarities of electrodes and using parameters of 0 to 5.5 V and 5 minutes. Temperature during reshaping was monitored with a thermocouple, and surface features were evaluated using light microscopy. RESULTS Reshaped specimen demonstrated mechanical stability similar to native cartilage tissue. Shape retention strongly correlated with increasing voltage and application time. Only a small current (<0.1 A) through the tissue was measured. Temperature change was less than 2 degrees C during electroforming, suggesting that electroforming likely results from some nonthermal mechanisms. Surface features indicated that electrodeposition may occur depending on electrode material and magnitude of the applied voltage. CONCLUSIONS These findings demonstrate that cartilage can be reshaped through the process we have described as "electroforming" by generating intrinsic differences in charge separation with negligible heat production.
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Affiliation(s)
- Ki-Hong Kevin Ho
- Beckman Laser Institute and Medical Clinic, Department of Biomedical Engineering, University of California, Irvine 92612, USA
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29
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Gu WY, Justiz MA. Apparatus for measuring the swelling dependent electrical conductivity of charged hydrated soft tissues. J Biomech Eng 2002; 124:790-3. [PMID: 12596649 DOI: 10.1115/1.1516571] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This paper describes a new apparatus and method for measuring swelling dependent electrical conductivity of charged hydrated soft tissues. The apparatus was calibrated using a conductivity standard. Swelling dependent specific conductivity of porcine annulus fibrosis (AF) samples was determined. The conductivity values for porcine AF were similar to those for human and bovine articular cartilage found in the literature. Results revealed a significant linear correlation between specific conductivity and water content for porcine AF tissues tested in phosphate buffered saline (PBS).
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Affiliation(s)
- W Y Gu
- Tissue Biomechanics Lab, Department of Biomedical Engineering, College of Engineering, University of Miami, Coral Gables, FL 33124, USA.
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30
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Gu WY, Justiz MA, Yao H. Electrical conductivity of lumbar anulus fibrosis: effects of porosity and fixed charge density. Spine (Phila Pa 1976) 2002; 27:2390-5. [PMID: 12438989 DOI: 10.1097/00007632-200211010-00014] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Experimental investigation of the electrical conductivity of normal and trypsin-treated lumbar anulus fibrosis specimens. OBJECTIVES To measure the electrical conductivity of intervertebral disc tissues and to study the effects of tissue porosity (volume fraction of water) and fixed charge density on the electrical conductivity of anulus fibrosis in physiologic saline. SUMMARY OF BACKGROUND DATA Specific electrical conductivity is one of the material properties of intervertebral discs. Their value depends on ion concentrations and ion diffusivities within the tissue, which in turn are functions of tissue composition and structure. To our knowledge, the electrical conductivity of intervertebral discs has not been studied. Investigation of the electrical conductivity of intervertebral discs and understanding of their relationship to tissue porosity and fixed charge density will provide insights into electromechanical phenomena (e.g., streaming potential) and ion transport in intervertebral discs. METHODS A total of 35 porcine lumbar anulus fibrosis specimens were divided into two groups: one control group (n = 10) and one trypsin-treated group (n = 25). The specimens in the control group were subjected to one-dimensional free swelling in phosphate-buffered saline (pH 7.4), and electrical conductivity and porosity (water content) were measured over a period of about 45 minutes. The specimens in the treated group were immersed in a trypsin solution (372 U/mL phosphate-buffered saline) for 45 minutes at room temperature, and the electrical conductivity and porosity were measured after treatment. The electrical conductivity was correlated to tissue porosity for the control and treated specimens. The influences of porosity and fixed charge density were studied. RESULTS The average value for control specimens was 5.60 +/- 0.89 mS/cm (mean +/- SD; n = 10) before swelling and 9.11 +/- 0.90 mS/cm (mean +/- SD; n = 10) after swelling. Tissue porosity increased from 0.74 +/- 0.03 (mean +/- SD; n = 10) before swelling to 0.83 +/- 0.02 (mean +/- SD; n = 10) after swelling. The trypsin treatment reduced anulus fibrosis porosity by 3.6% (P < 0.05) and conductivity by 13% (P < 0.05) compared to those for control specimens after swelling. No significant changes werefound in wet and dry tissue densities between control and treated groups. There was a significant, linear correlation between conductivity and porosity for control anulus fibrosis specimens (R2 = 0.87; 86 measurements). CONCLUSIONS Measured electrical conductivity was sensitive to tissue porosity, but not to fixed charged density for anulus fibrosis specimens in phosphate-buffered saline.
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Affiliation(s)
- Wei Yong Gu
- Tissue Biomechanics Laboratory, Department of Biomedical Engineering, University of Miami, Coral Gables, Florida 33124-0621, USA.
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Mow VC, Guo XE. Mechano-electrochemical properties of articular cartilage: their inhomogeneities and anisotropies. Annu Rev Biomed Eng 2002; 4:175-209. [PMID: 12117756 DOI: 10.1146/annurev.bioeng.4.110701.120309] [Citation(s) in RCA: 279] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In this chapter, the recent advances in cartilage biomechanics and electromechanics are reviewed and summarized. Our emphasis is on the new experimental techniques in cartilage mechanical testing, new experimental and theoretical findings in cartilage biomechanics and electromechanics, and emerging theories and computational modeling of articular cartilage. The charged nature and depth-dependent inhomogeneity in mechano-electrochemical properties of articular cartilage are examined, and their importance in the normal and/or pathological structure-function relationships with cartilage is discussed, along with their pathophysiological implications. Developments in theoretical and computational models of articular cartilage are summarized, and their application in cartilage biomechanics and biology is reviewed. Future directions in cartilage biomechanics and mechano-biology research are proposed.
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Affiliation(s)
- Van C Mow
- Department of Biomedical Engineering, Columbia University New York, New York 10027, USA.
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32
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Garon M, Légaré A, Guardo R, Savard P, Buschmann MD. Streaming potentials maps are spatially resolved indicators of amplitude, frequency and ionic strength dependant responses of articular cartilage to load. J Biomech 2002; 35:207-16. [PMID: 11784539 DOI: 10.1016/s0021-9290(01)00197-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Streaming potential distributions were measured on the surface of articular cartilage in uniaxial unconfined compression using a linear array of microelectrodes. Potential profiles were obtained for sinusoidal and ramp/stress-relaxation displacements and exhibited dependencies on radial position, sinusoidal amplitude and frequency, time during stress relaxation, and on ionic strength. The measurements agreed with trends predicted by biphasic and related models. In particular, the absolute potential amplitude was maximal at the disk center, as was the predicted fluid pressure and the potential gradient (the electric field) was seen to be maximal at the disk periphery, as was the predicted fluid velocity. We also observed a similarity between non-linear behavior of streaming potential amplitude and load amplitude with respect to sinusoidal displacement amplitude. Taken together, these results support many of the phenomena concerning relative fluid-solid movement and fluid pressurization predicted by biphasic and related models, and they indicate the general utility of spatially resolved measurements of streaming potentials for the investigation of electromechanical phenomena in tissues. For example, these streaming potential maps could be used to non-destructively diagnose cartilage extracellular matrix composition and function, as well as to quantify spatially and temporally varying physical signals in cartilage that can induce cellular and extracellular biological responses to load.
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Affiliation(s)
- M Garon
- Institute of Biomedical Engineering, Ecole Polytechnique of Montreal, P.O. Box 6079 Station Centre-ville, Montreal, Quebec, Canada H3C 3A7.
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Chen AC, Bae WC, Schinagl RM, Sah RL. Depth- and strain-dependent mechanical and electromechanical properties of full-thickness bovine articular cartilage in confined compression. J Biomech 2001; 34:1-12. [PMID: 11425068 DOI: 10.1016/s0021-9290(00)00170-6] [Citation(s) in RCA: 198] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Compression tests have often been performed to assess the biomechanical properties of full-thickness articular cartilage. We tested whether the apparent homogeneous strain-dependent properties, deduced from such tests, reflect both strain- and depth-dependent material properties. Full-thickness bovine articular cartilage was tested by oscillatory confined compression superimposed on a static offset up to 45%. and the data fit to estimate modulus, permeability, and electrokinetic coefficient assuming homogeneity. Additional tests on partial-thickness cartilage were then performed to assess depth- and strain-dependent properties in an inhomogeneous model, assuming three discrete layers (i = 1 starting from the articular surface, to i = 3 up to the subchondral bone). Estimates of the zero-strain equilibrium confined compression modulus (H(A0)), the zero-strain permeability (kp0) and deformation dependence constant (M), and the deformation-dependent electrokinetic coefficient (ke) differed among individual layers of cartilage and full-thickness cartilage. HiA0 increased from layer 1 to 3 (0.27 to 0.71 MPa), and bracketed the apparent homogeneous value (0.47 MPa). ki(p0) decreased from layer 1 to 3 (4.6 x 10(-15) to 0.50 x 10(-15) m2/Pa s) and was less than the homogeneous value (7.3 x 10(-15) m2/Pa s), while Mi increased from layer 1 to 3 (5.5 to 7.4) and became similar to the homogeneous value (8.4). The amplitude of ki(e) increased markedly with compressive strain, as did the homogeneous value: at low strain, it was lowest near the articular surface and increased to a peak in the middle-deep region. These results help to interpret the biomechanical assessment of full-thickness articular cartilage.
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Affiliation(s)
- A C Chen
- Department of Bioengineering, Institute for Biomedical Engineering, University of California-San Diego, La Jolla 92093-0412, USA
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Chen CT, McCabe RP, Grodzinsky AJ, Vanderby R. Transient and cyclic responses of strain-generated potential in rabbit patellar tendon are frequency and pH dependent. J Biomech Eng 2000; 122:465-70. [PMID: 11091946 DOI: 10.1115/1.1289639] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The goal of this study was to expand understanding of strain-generated potential (SGP) in ligamentous or tendinous tissues. Most SGP studies in the past have focused on cartilage or bone. Herein, rabbit patellar tendon (PT) was used as a model. Each patellar tendon had two Ag/AgCl electrodes inserted at axial positions of 1/4 and 1/2 from patellar to tibial insertions. Each specimen was electrically isolated, gripped in a servohydraulic test system, and then subjected to a short session of uniaxial haversine tension (2.5 percent maximum strain) at a frequency of 0.5, 1.0, 2.0, or 5.0 Hz. A cyclic (sinusoidal) electrical potential superimposed upon a larger transient (exponentially asymptotic) potential was consistently observed. Upon termination of loading, the cyclic SGP ended, and the shifted baseline of the SGP exponentially decayed and asymptotically returned to a residual potential which over all specimens was not different than the original potential. The transient and cyclic SGPs were frequency dependent (P < 0.001, P = 0.06, respectively). To our knowledge, this transient portion of the SGP, although theoretically predicted by Suh (1996, Biorheology, 33, pp. 289-304) and Chen (1996, Ph.D. thesis, University of Wisconsin-Madison) has not been observed in other experiments using different protocols. Additional PTs were dehydrated and the rehydrated in solution at different pH levels. The magnitude of SGPs increased in basic solution (pH 9.5) but diminished in pH 4.7 buffer. This pH dependency suggests that electrokinetics is the dominant mechanism for the transient and cyclic responses of the SGPs, although this study does not provide direct evidence.
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Affiliation(s)
- C T Chen
- Department of Mechanical Engineering, University of Wisconsin, Madison 53706, USA
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Lai WM, Mow VC, Sun DD, Ateshian GA. On the electric potentials inside a charged soft hydrated biological tissue: streaming potential versus diffusion potential. J Biomech Eng 2000; 122:336-46. [PMID: 11036556 DOI: 10.1115/1.1286316] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The main objective of this study is to determine the nature of electric fields inside articular cartilage while accounting for the effects of both streaming potential and diffusion potential. Specifically, we solve two tissue mechano-electrochemical problems using the triphasic theories developed by Lai et al. (1991, ASME J. Biomech Eng., 113, pp. 245-258) and Gu et al. (1998, ASME J. Biomech. Eng., 120, pp. 169-180) (1) the steady one-dimensional permeation problem; and (2) the transient one-dimensional ramped-displacement, confined-compression, stress-relaxation problem (both in an open circuit condition) so as to be able to calculate the compressive strain, the electric potential, and the fixed charged density (FCD) inside cartilage. Our calculations show that in these two technically important problems, the diffusion potential effects compete against the flow-induced kinetic effects (streaming potential) for dominance of the electric potential inside the tissue. For softer tissues of similar FCD (i.e., lower aggregate modulus), the diffusion potential effects are enhanced when the tissue is being compressed (i.e., increasing its FCD in a nonuniform manner) either by direct compression or by drag-induced compaction; indeed, the diffusion potential effect may dominate over the streaming potential effect. The polarity of the electric potential field is in the same direction of interstitial fluid flow when streaming potential dominates, and in the opposite direction of fluid flow when diffusion potential dominates. For physiologically realistic articular cartilage material parameters, the polarity of electric potential across the tissue on the outside (surface to surface) may be opposite to the polarity across the tissue on the inside (surface to surface). Since the electromechanical signals that chondrocytes perceive in situ are the stresses, strains, pressures and the electric field generated inside the extracellular matrix when the tissue is deformed, the results from this study offer new challenges for the understanding of possible mechanisms that control chondrocyte biosyntheses.
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Affiliation(s)
- W M Lai
- Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
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Gu WY, Mao XG, Rawlins BA, Iatridis JC, Foster RJ, Sun DN, Weidenbaum M, Mow VC. Streaming potential of human lumbar anulus fibrosus is anisotropic and affected by disc degeneration. J Biomech 1999; 32:1177-82. [PMID: 10541067 DOI: 10.1016/s0021-9290(99)00118-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The streaming potential responses of non-degenerate and degenerate human anulus fibrosus were measured in a one-dimensional permeation configuration under static and dynamic loading conditions. The goal of this study was to investigate the influence of the changes in tissue structure and composition on the electrokinetic behavior of intervertebral disc tissues. It was found that the static streaming potential of the anulus fibrosus depended on the degenerative grade of the discs (p = 0.0001) and on the specimen orientation in which the fluid flows (p = 0.0001). For a statically applied pressure of 0.07 MPa, the ratio of streaming potential to applied pressure ranged from 5.3 to 6.9 mV/MPa and was largest for Grade I tissue with axial orientation and lowest for Grade III tissue with circumferential orientation. The dynamic streaming potential responses of anulus fibrosus were sensitive to the degeneration of the disc: the total harmonic distortion factor increased by 108%, from 3.92 +/- 0.66% (mean +/- SD) for Grade I specimens to 8.15 +/- 3.05% for Grades II and III specimens. The alteration of streaming potential reflects the changes in tissue composition and structure with degeneration. To our knowledge, this is the first reported data for the streaming potential of human intervertebral disc tissues. Knowledge of the streaming potential response of the intervertebral disc provides an understanding of potentially important signal transduction mechanisms in the disc and of the etiology of intervertebral disc degeneration.
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Affiliation(s)
- W Y Gu
- Department of Biomedical Engineering, College of Engineering, University of Miami, Coral Gables, FL 33124-0621, USA.
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