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Andress BD, Irwin RM, Puranam I, Hoffman BD, McNulty AL. A Tale of Two Loads: Modulation of IL-1 Induced Inflammatory Responses of Meniscal Cells in Two Models of Dynamic Physiologic Loading. Front Bioeng Biotechnol 2022; 10:837619. [PMID: 35299636 PMCID: PMC8921261 DOI: 10.3389/fbioe.2022.837619] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 01/24/2022] [Indexed: 12/14/2022] Open
Abstract
Meniscus injuries are highly prevalent, and both meniscus injury and subsequent surgery are linked to the development of post-traumatic osteoarthritis (PTOA). Although the pathogenesis of PTOA remains poorly understood, the inflammatory cytokine IL-1 is elevated in synovial fluid following acute knee injuries and causes degradation of meniscus tissue and inhibits meniscus repair. Dynamic mechanical compression of meniscus tissue improves integrative meniscus repair in the presence of IL-1 and dynamic tensile strain modulates the response of meniscus cells to IL-1. Despite the promising observed effects of physiologic mechanical loading on suppressing inflammatory responses of meniscus cells, there is a lack of knowledge on the global effects of loading on meniscus transcriptomic profiles. In this study, we compared two established models of physiologic mechanical stimulation, dynamic compression of tissue explants and cyclic tensile stretch of isolated meniscus cells, to identify conserved responses to mechanical loading. RNA sequencing was performed on loaded and unloaded meniscus tissue or isolated cells from inner and outer zones, with and without IL-1. Overall, results from both models showed significant modulation of inflammation-related pathways with mechanical stimulation. Anti-inflammatory effects of loading were well-conserved between the tissue compression and cell stretch models for inner zone; however, the cell stretch model resulted in a larger number of differentially regulated genes. Our findings on the global transcriptomic profiles of two models of mechanical stimulation lay the groundwork for future mechanistic studies of meniscus mechanotransduction, which may lead to the discovery of novel therapeutic targets for the treatment of meniscus injuries.
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Affiliation(s)
| | - Rebecca M. Irwin
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, United States
| | - Ishaan Puranam
- Department of Biomedical Engineering, Duke University, Durham, NC, United States
| | - Brenton D. Hoffman
- Department of Biomedical Engineering, Duke University, Durham, NC, United States
- Department of Cell Biology, Duke University, Durham, NC, United States
| | - Amy L. McNulty
- Department of Pathology, Duke University, Durham, NC, United States
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, United States
- *Correspondence: Amy L. McNulty,
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2
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Szojka ARA, Liang Y, Marqueti RDC, Moore CN, Erkut EJN, Kunze M, Mulet-Sierra A, Jomha NM, Adesida AB. Time course of 3D fibrocartilage formation by expanded human meniscus fibrochondrocytes in hypoxia. J Orthop Res 2022; 40:495-503. [PMID: 33788325 DOI: 10.1002/jor.25046] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Revised: 03/04/2021] [Accepted: 03/24/2021] [Indexed: 02/04/2023]
Abstract
Adult human meniscus fibrocartilage is avascular and nonhealing after injury. Meniscus tissue engineering aims to replace injured meniscus with lab-grown fibrocartilage. Dynamic culture systems may be necessary to generate fibrocartilage of sufficient mechanical properties for implantation; however, the optimal static preculture conditions before initiation of dynamic culture are unknown. This study thus investigated the time course of fibrocartilage formation by human meniscus fibrochondrocytes on a three-dimensional biomaterial scaffold under various static conditions. Human meniscus fibrochondrocytes from partial meniscectomy were expanded to passage 1 (P1) or P2 (3.0 ± 0.4 and 6.5 ± 0.6 population doublings), seeded onto type I collagen scaffolds, and grown in hypoxia (HYP, 3% O2 ) or normoxia (NRX, 20% O2 ) for 3, 6, and 9 weeks. Mechanical properties were not different between P1 and P2 cell-based constructs. Mechanical properties were lower in HYP, increased continually in NRX only, and were positively correlated with glycosaminoglycan content and accumulation of hyaline cartilage-like matrix components. The most mechanically competent tissues (NRX/9 weeks) reached 1/5 of the native meniscus instantaneous compression modulus but had an increasingly hypertrophic matrix-forming phenotype. HYP consistently suppressed the hypertrophic phenotype. The results provide baselines of engineered meniscus fibrocartilage properties under static conditions, which can be used to select a preculture strategy for dynamic culture depending on the desired combination of mechanical properties, hyaline cartilage-like matrix abundance, and hypertrophic phenotype.
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Affiliation(s)
- Alexander R A Szojka
- Department of Surgery, Divisions of Orthopedic Surgery and Surgical Research, Faculty of Medicine and Dentistry, Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, Alberta, Canada
| | - Yan Liang
- Department of Surgery, Divisions of Orthopedic Surgery and Surgical Research, Faculty of Medicine and Dentistry, Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, Alberta, Canada
| | - Rita de Cássia Marqueti
- Graduate Program of Rehabilitation Sciences, University of Brasília (UnB), Brasília, Distrito Federal, Brazil
| | - Colleen N Moore
- Department of Surgery, Divisions of Orthopedic Surgery and Surgical Research, Faculty of Medicine and Dentistry, Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, Alberta, Canada
| | - Esra J N Erkut
- Department of Surgery, Divisions of Orthopedic Surgery and Surgical Research, Faculty of Medicine and Dentistry, Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, Alberta, Canada
| | - Melanie Kunze
- Department of Surgery, Divisions of Orthopedic Surgery and Surgical Research, Faculty of Medicine and Dentistry, Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, Alberta, Canada
| | - Aillette Mulet-Sierra
- Department of Surgery, Divisions of Orthopedic Surgery and Surgical Research, Faculty of Medicine and Dentistry, Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, Alberta, Canada
| | - Nadr M Jomha
- Department of Surgery, Divisions of Orthopedic Surgery and Surgical Research, Faculty of Medicine and Dentistry, Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, Alberta, Canada
| | - Adetola B Adesida
- Department of Surgery, Divisions of Orthopedic Surgery and Surgical Research, Faculty of Medicine and Dentistry, Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, Alberta, Canada
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3
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Constitutive modeling of menisci tissue: a critical review of analytical and numerical approaches. Biomech Model Mechanobiol 2020; 19:1979-1996. [PMID: 32572727 DOI: 10.1007/s10237-020-01352-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 05/28/2020] [Indexed: 02/07/2023]
Abstract
Menisci are fibrocartilaginous disks consisting of soft tissue with a complex biomechanical structure. They are critical determinants of the kinematics as well as the stability of the knee joint. Several studies have been carried out to formulate tissue mechanical behavior, leading to the development of a wide spectrum of constitutive laws. In addition to developing analytical tools, extensive numerical studies have been conducted on menisci modeling. This study reviews the developments of the most widely used continuum models of the meniscus mechanical properties in conjunction with emerging analytical and numerical models used to study the meniscus. The review presents relevant approaches and assumptions used to develop the models and includes discussions regarding strengths, weaknesses, and discrepancies involved in the presented models. The study presents a comprehensive coverage of relevant publications included in Compendex, EMBASE, MEDLINE, PubMed, ScienceDirect, Springer, and Scopus databases. This review aims at opening novel avenues for improving menisci modeling within the framework of constitutive modeling through highlighting the needs for further research directed toward determining key factors in gaining insight into the biomechanics of menisci which is crucial for the elaborate design of meniscal replacements.
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4
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Tarafder S, Park G, Lee CH. Explant models for meniscus metabolism, injury, repair, and healing. Connect Tissue Res 2020; 61:292-303. [PMID: 31842590 PMCID: PMC7190414 DOI: 10.1080/03008207.2019.1702031] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 12/03/2019] [Indexed: 02/03/2023]
Abstract
Purpose/Aim: Knee meniscus is a wedge-shaped fibrocartilaginous tissue, playing important roles in maintaining joint stability and function. Injuries to the meniscus, particularly with the avascular inner third zone, hardly heal and frequently progress into structural breakdown, followed by the initiation of osteoarthritis. As the importance of meniscus in joint function and diseases is being recognized, the field of meniscus research is growing. Not only development, biology, and metabolism but also injury, repair, and healing of meniscus are being actively investigated. As meniscus functions as an integrated unit of a knee joint, in vivo models with various species have been the predominant method for studying meniscus pathophysiology and for testing healing/regeneration strategies. However, in vivo models for meniscus studies suffer from low reproducibility and high cost. To complement the limitations of in vivo animal models, several types of meniscus explants have been applied as highly controlled, standardized in vitro models to investigate meniscus metabolism, pathophysiology, and repair or regeneration process. This review summarizes and compares the existing meniscus explant models. We also discuss the advantages and disadvantages of each explant model.Conclusion: Despite few outstanding challenges, meniscus explant models have potential to serve as an effective tool for investigations of meniscus metabolism, injury, repair and healing.
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Affiliation(s)
- Solaiman Tarafder
- Regenerative Engineering Laboratory, Center for Advanced Regenerative Technologies (cART), Columbia University Irving Medical Center, 630 West 168 Street, VC12-211, New York, NY 10032
| | - Gayoung Park
- Regenerative Engineering Laboratory, Center for Advanced Regenerative Technologies (cART), Columbia University Irving Medical Center, 630 West 168 Street, VC12-211, New York, NY 10032
| | - Chang H. Lee
- Regenerative Engineering Laboratory, Center for Advanced Regenerative Technologies (cART), Columbia University Irving Medical Center, 630 West 168 Street, VC12-211, New York, NY 10032
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5
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Early degeneration of the meniscus revealed by microbiomechanical alteration in a rabbit anterior cruciate ligament transection model. J Orthop Translat 2020; 21:146-152. [PMID: 32309140 PMCID: PMC7152828 DOI: 10.1016/j.jot.2019.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 05/21/2019] [Accepted: 06/03/2019] [Indexed: 02/07/2023] Open
Abstract
Background The microbiomechanical properties of the meniscus influence the cell response to the surrounding biomechanical environment and are beneficial to understand meniscus repairing and healing. To date, however, this information remains ambiguous. This study aims to characterise the microbiomechanical properties of the meniscus after degeneration in a rabbit anterior cruciate ligament transection (ACLT) model and to analyse the corresponding histology at the macroscale and chemical composition. Methods Twenty New Zealand white rabbits were used. Menisci were collected from the knee joints 4 and 8 weeks after the ACLT and from those of the corresponding control groups. The central portions of both medial and lateral menisci were investigated using atomic force microscopy, histological study, and an energy-dispersive spectrometer. The evaluation was conducted regionally within the inner, middle, and outer sites from the top layer (facing the femoral surface) to the bottom layer (facing the tibial surface) in both the lateral and medial menisci to obtain the site-dependent properties. Results At 4 weeks after surgery, the dynamic elastic modulus at the microlevel increased significantly at both the top and bottom layers compared with the intact meniscus (P = 0.021). At 8 weeks after surgery, the stiffening occurred in all regions (P = 0.030). The medial meniscus showed greater change than the lateral meniscus. All these microbiomechanical alterations occurred before the histological findings at the macroscale. Conclusion The microbiomechanical properties in the meniscus changed significantly after ACLT and were site dependent. Their alterations occurred before the histological changes of degeneration were observed. The Translational Potential of this Article The results of our study indicated that degeneration promoted meniscus stiffening. Thus, they provide a better understanding of the disease process affecting the meniscus. Our results might be beneficial to understand how mechanical forces distribute throughout the healthy and pathologic joint. They indicate the possibility of early diagnosis using a minimally invasive arthroscopic tool, as well as they might guide treatment to the healthy and pathologic meniscus and joint.
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Jacob G, Shimomura K, Krych AJ, Nakamura N. The Meniscus Tear: A Review of Stem Cell Therapies. Cells 2019; 9:E92. [PMID: 31905968 PMCID: PMC7016630 DOI: 10.3390/cells9010092] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 12/20/2019] [Accepted: 12/28/2019] [Indexed: 02/07/2023] Open
Abstract
Meniscal injuries have posed a challenging problem for many years, especially considering that historically the meniscus was considered to be a structure with no important role in the knee joint. This led to earlier treatments aiming at the removal of the entire structure in a procedure known as a meniscectomy. However, with the current understanding of the function and roles of the meniscus, meniscectomy has been identified to accelerate joint degradation significantly and is no longer a preferred treatment option in meniscal tears. Current therapies are now focused to regenerate, repair, or replace the injured meniscus to restore its native function. Repairs have improved in technique and materials over time, with various implant devices being utilized and developed. More recently, strategies have applied stem cells, tissue engineering, and their combination to potentiate healing to achieve superior quality repair tissue and retard the joint degeneration associated with an injured or inadequately functioning meniscus. Accordingly, the purpose of this current review is to summarize the current available pre-clinical and clinical literature using stem cells and tissue engineering for meniscal repair and regeneration.
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Affiliation(s)
- George Jacob
- Department and Orthopaedic Surgery, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan; (G.J.); (K.S.)
| | - Kazunori Shimomura
- Department and Orthopaedic Surgery, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan; (G.J.); (K.S.)
| | - Aaron J. Krych
- Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN 55905, USA
| | - Norimasa Nakamura
- Institute for Medical Science in Sports, Osaka Health Science University, Osaka 530-0043, Japan
- Global Centre for Medical Engineering and Informatics, Osaka University, Osaka 565-0871, Japan
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7
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Ruprecht JC, Waanders TD, Rowland CR, Nishimuta JF, Glass KA, Stencel J, DeFrate LE, Guilak F, Weinberg JB, McNulty AL. Meniscus-Derived Matrix Scaffolds Promote the Integrative Repair of Meniscal Defects. Sci Rep 2019; 9:8719. [PMID: 31213610 PMCID: PMC6582057 DOI: 10.1038/s41598-019-44855-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 05/24/2019] [Indexed: 01/05/2023] Open
Abstract
Meniscal tears have a poor healing capacity, and damage to the meniscus is associated with significant pain, disability, and progressive degenerative changes in the knee joint that lead to osteoarthritis. Therefore, strategies to promote meniscus repair and improve meniscus function are needed. The objective of this study was to generate porcine meniscus-derived matrix (MDM) scaffolds and test their effectiveness in promoting meniscus repair via migration of endogenous meniscus cells from the surrounding meniscus or exogenously seeded human bone marrow-derived mesenchymal stem cells (MSCs). Both endogenous meniscal cells and MSCs infiltrated the MDM scaffolds. In the absence of exogenous cells, the 8% MDM scaffolds promoted the integrative repair of an in vitro meniscal defect. Dehydrothermal crosslinking and concentration of the MDM influenced the biochemical content and shear strength of repair, demonstrating that the MDM can be tailored to promote tissue repair. These findings indicate that native meniscus cells can enhance meniscus healing if a scaffold is provided that promotes cellular infiltration and tissue growth. The high affinity of cells for the MDM and the ability to remodel the scaffold reveals the potential of MDM to integrate with native meniscal tissue to promote long-term repair without necessarily requiring exogenous cells.
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Affiliation(s)
- Jacob C Ruprecht
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.,Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, USA
| | - Taylor D Waanders
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Christopher R Rowland
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.,Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, USA
| | - James F Nishimuta
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, USA
| | - Katherine A Glass
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Jennifer Stencel
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Louis E DeFrate
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.,Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, USA.,Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, USA
| | - Farshid Guilak
- Department of Orthopaedic Surgery, Washington University, St. Louis, MO, USA.,Shriners Hospitals for Children - St. Louis, St. Louis, MO, USA
| | - J Brice Weinberg
- Department of Medicine, Duke University School of Medicine, Durham, NC, USA.,VA Medical Center, Durham, NC, USA
| | - Amy L McNulty
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC, USA. .,Department of Pathology, Duke University, Durham, NC, USA.
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8
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Regional dependency of bovine meniscus biomechanics on the internal structure and glycosaminoglycan content. J Mech Behav Biomed Mater 2019; 94:186-192. [DOI: 10.1016/j.jmbbm.2019.02.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 02/14/2019] [Accepted: 02/19/2019] [Indexed: 12/22/2022]
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9
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Peloquin JM, Santare MH, Elliott DM. Short cracks in knee meniscus tissue cause strain concentrations, but do not reduce ultimate stress, in single-cycle uniaxial tension. ROYAL SOCIETY OPEN SCIENCE 2018; 5:181166. [PMID: 30564409 PMCID: PMC6281910 DOI: 10.1098/rsos.181166] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 10/19/2018] [Indexed: 05/15/2023]
Abstract
Tears are central to knee meniscus pathology and, from a mechanical perspective, are crack-like defects (cracks). In many materials, cracks create stress concentrations that cause progressive local rupture and reduce effective strength. It is currently unknown if cracks in meniscus have these consequences; if they do, this would have repercussions for management of meniscus pathology. The objective of this study was to determine if a short crack in meniscus tissue, which mimics a preclinical meniscus tear, (a) causes crack growth and reduces effective strength, (b) creates a near-tip strain concentration and (c) creates unloaded regions on either side of the crack. Specimens with and without cracks were tested in uniaxial tension and compared in terms of macroscopic stress-strain curves and digital image correlation strain fields. The strain fields were used as an indicator of stress concentrations and unloaded regions. Effective strength was found to be insensitive to the presence of a crack (potential effect < 0.86 s.d.; β = 0.2), but significant strain concentrations, which have the potential to lead to long-term accumulation of tissue or cell damage, were observed near the crack tip.
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Affiliation(s)
- John M. Peloquin
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
| | - Michael H. Santare
- Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - Dawn M. Elliott
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
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10
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Cook AE, Stoker AM, Leary EV, Pfeiffer FM, Cook JL. Metabolic responses of meniscal explants to injury and inflammation ex vivo. J Orthop Res 2018; 36:2657-2663. [PMID: 29745431 DOI: 10.1002/jor.24045] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 05/07/2018] [Indexed: 02/06/2023]
Abstract
This study was designed to characterize metabolic responses of meniscal tissue explants to injury and inflammation. We hypothesized that impact injury and interleukin (IL-1β) stimulation of meniscal explants would result in significant increases in matrix metalloproteinase (MMP) activity and relevant cytokine production compared to controls. Mature canine meniscal explants (n = 9/group) were randomly assigned to: (i) IL-1β (0.1 ng/ml) treated (IL); (ii) 25% strain (25); (iii) 75% strain (75); (iv) 25% + IL-1β (25IL); (v) 75% + IL-1β (75IL); or (vi) 0% + no IL-1β control (NC). Explants were impacted at 100 mm/s to 0%, 25%, or 75% strain and then cultured for 12 days with or without 0.1 ng/ml rcIL-1β. Media were refreshed every 3 days and analyzed for MMP activity, ADAMTS-4 activity, MMP-1, MMP-2, MMP-3, GAG, NO, PGE2 , IL-6, IL-8, MCP-1, and KC concentrations. Treatment with IL-1β alone significantly increased NO, PGE2, general MMP activity, IL-6, IL-8, KC, and MCP-1 media concentrations compared to negative controls. Impact at 75% significantly increased PGE2, IL-6, IL-8, and KC media concentrations compared to negative controls. The combination of IL-1β and 75% strain significantly increased production of PGE2 compared to IL-1β or 75% strain alone. Impact injury to meniscal explants ex vivo is associated with increased production of pro-inflammatory mediators and degradative enzyme activity, which are exacerbated by stimulation with IL-1β. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2657-2663, 2018.
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Affiliation(s)
- Alex E Cook
- Kansas City University of Medicine and Biosciences, Kansas City, Missouri.,Thompson Laboratory for Regenerative Orthopaedics, University of Missouri, Columbia, Missouri
| | - Aaron M Stoker
- Thompson Laboratory for Regenerative Orthopaedics, University of Missouri, Columbia, Missouri.,Department of Orthopaedic Surgery, University of Missouri, 1100 Virginia Ave., DC953.00, Columbia 65212, Missouri
| | - Emily V Leary
- Department of Orthopaedic Surgery, University of Missouri, 1100 Virginia Ave., DC953.00, Columbia 65212, Missouri
| | - Ferris M Pfeiffer
- Thompson Laboratory for Regenerative Orthopaedics, University of Missouri, Columbia, Missouri.,Department of Orthopaedic Surgery, University of Missouri, 1100 Virginia Ave., DC953.00, Columbia 65212, Missouri
| | - James L Cook
- Thompson Laboratory for Regenerative Orthopaedics, University of Missouri, Columbia, Missouri.,Department of Orthopaedic Surgery, University of Missouri, 1100 Virginia Ave., DC953.00, Columbia 65212, Missouri
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11
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Peloquin JM, Santare MH, Elliott DM. Advances in Quantification of Meniscus Tensile Mechanics Including Nonlinearity, Yield, and Failure. J Biomech Eng 2016; 138:021002. [PMID: 26720401 DOI: 10.1115/1.4032354] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Indexed: 11/08/2022]
Abstract
The meniscus provides crucial knee function and damage to it leads to osteoarthritis of the articular cartilage. Accurate measurement of its mechanical properties is therefore important, but there is uncertainty about how the test procedure affects the results, and some key mechanical properties are reported using ad hoc criteria (modulus) or not reported at all (yield). This study quantifies the meniscus' stress-strain curve in circumferential and radial uniaxial tension. A fiber recruitment model was used to represent the toe region of the stress-strain curve, and new reproducible and objective procedures were implemented for identifying the yield point and measuring the elastic modulus. Patterns of strain heterogeneity were identified using strain field measurements. To resolve uncertainty regarding whether rupture location (i.e., midsubstance rupture versus at-grip rupture) influences the measured mechanical properties, types of rupture were classified in detail and compared. Dogbone (DB)-shaped specimens are often used to promote midsubstance rupture; to determine if this is effective, we compared DB and rectangle (R) specimens in both the radial and circumferential directions. In circumferential testing, we also compared expanded tab (ET) specimens under the hypothesis that this shape would more effectively secure the meniscus' curved fibers and thus produce a stiffer response. The fiber recruitment model produced excellent fits to the data. Full fiber recruitment occurred approximately at the yield point, strongly supporting the model's physical interpretation. The strain fields, especially shear and transverse strain, were extremely heterogeneous. The shear strain field was arranged in pronounced bands of alternating positive and negative strain in a pattern similar to the fascicle structure. The site and extent of failure showed great variation, but did not affect the measured mechanical properties. In circumferential tension, ET specimens underwent earlier and more rapid fiber recruitment, had less stretch at yield, and had greater elastic modulus and peak stress. No significant differences were observed between R and DB specimens in either circumferential or radial tension. Based on these results, ET specimens are recommended for circumferential tests and R specimens for radial tests. In addition to the data obtained, the procedural and modeling advances made in this study are a significant step forward for meniscus research and are applicable to other fibrous soft tissues.
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12
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Abstract
Tendon exhibits anisotropic, inhomogeneous and viscoelastic mechanical properties that are determined by its complicated hierarchical structure and varying amounts/organization of different tissue constituents. Although extensive research has been conducted to use modelling approaches to interpret tendon structure-function relationships in combination with experimental data, many issues remain unclear (i.e. the role of minor components such as decorin, aggrecan and elastin), and the integration of mechanical analysis across different length scales has not been well applied to explore stress or strain transfer from macro- to microscale. This review outlines mathematical and computational models that have been used to understand tendon mechanics at different scales of the hierarchical organization. Model representations at the molecular, fibril and tissue levels are discussed, including formulations that follow phenomenological and microstructural approaches (which include evaluations of crimp, helical structure and the interaction between collagen fibrils and proteoglycans). Multiscale modelling approaches incorporating tendon features are suggested to be an advantageous methodology to understand further the physiological mechanical response of tendon and corresponding adaptation of properties owing to unique in vivo loading environments.
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Affiliation(s)
- Fei Fang
- Department of Mechanical Engineering and Materials Science , Washington University in St Louis , St Louis, MO 63130 , USA
| | - Spencer P Lake
- Department of Mechanical Engineering and Materials Science, Washington University in St Louis, St Louis, MO 63130, USA; Department of Biomedical Engineering, Washington University in St Louis, St Louis, MO 63130, USA; Department of Orthopaedic Surgery, Washington University in St Louis, St Louis, MO 63130, USA
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13
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Abstract
The meniscus plays a critical biomechanical role in the knee, providing load support, joint stability, and congruity. Importantly, growing evidence indicates that the mechanobiologic response of meniscal cells plays a critical role in the physiologic, pathologic, and repair responses of the meniscus. Here we review experimental and theoretical studies that have begun to directly measure the biomechanical effects of joint loading on the meniscus under physiologic and pathologic conditions, showing that the menisci are exposed to high contact stresses, resulting in a complex and nonuniform stress-strain environment within the tissue. By combining microscale measurements of the mechanical properties of meniscal cells and their pericellular and extracellular matrix regions, theoretical and experimental models indicate that the cells in the meniscus are exposed to a complex and inhomogeneous environment of stress, strain, fluid pressure, fluid flow, and a variety of physicochemical factors. Studies across a range of culture systems from isolated cells to tissues have revealed that the biological response of meniscal cells is directly influenced by physical factors, such as tension, compression, and hydrostatic pressure. In addition, these studies have provided new insights into the mechanotransduction mechanisms by which physical signals are converted into metabolic or pro/anti-inflammatory responses. Taken together, these in vivo and in vitro studies show that mechanical factors play an important role in the health, degeneration, and regeneration of the meniscus. A more thorough understanding of the mechanobiologic responses of the meniscus will hopefully lead to therapeutic approaches to prevent degeneration and enhance repair of the meniscus.
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14
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Kwok J, Grogan S, Meckes B, Arce F, Lal R, D'Lima D. Atomic force microscopy reveals age-dependent changes in nanomechanical properties of the extracellular matrix of native human menisci: implications for joint degeneration and osteoarthritis. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2014; 10:1777-85. [PMID: 24972006 DOI: 10.1016/j.nano.2014.06.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 06/11/2014] [Accepted: 06/15/2014] [Indexed: 10/25/2022]
Abstract
UNLABELLED With aging, the menisci become more susceptible to degeneration due to sustained mechanical stress accompanied by age-related changes in the extracellular matrix (ECM). However, the mechanistic relationship between age-related meniscal degeneration and osteoarthritis (OA) development is not yet fully understood. We have examined the nanomechanical properties of the ECM of normal, aged, and degenerated human menisci using atomic force microscopy (AFM). Elasticity maps of the ECM revealed a unique differential qualitative nanomechanical profile of healthy young tissue: prominent unimodal peaks in the elastic moduli distribution in each region (outer, middle, and inner). Healthy aged tissue showed similar regional elasticity but with both unimodal and bimodal distributions that included higher elastic moduli. In contrast, degenerated OA tissue showed the broadest distribution without prominent peaks indicative of substantially increased mechanical heterogeneity in the ECM. AFM analysis reveals distinct regional nanomechanical profiles that underlie aging-dependent tissue degeneration and OA. FROM THE CLINICAL EDITOR The authors of this study used atomic force microscopy to determine the nanomechanical properties of the extracellular matrix in normal and degenerated human menisci, as well as in menisci undergoing healthy aging. Comparison of these properties help to understand the relationship between healthy ageing, and age-dependent joint degeneration and osteoarthritis.
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Affiliation(s)
- Jeanie Kwok
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, USA; Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA, USA; Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, CA, USA
| | - Shawn Grogan
- Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, CA, USA
| | - Brian Meckes
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Fernando Arce
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, USA; Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Ratnesh Lal
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, USA; Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA, USA; Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.
| | - Darryl D'Lima
- Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, CA, USA.
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Bennetts CJ, Sibole S, Erdemir A. Automated generation of tissue-specific three-dimensional finite element meshes containing ellipsoidal cellular inclusions. Comput Methods Biomech Biomed Engin 2014; 18:1293-304. [PMID: 24708340 DOI: 10.1080/10255842.2014.900545] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Finite element analysis provides a means of describing cellular mechanics in tissue, which can be useful in understanding and predicting physiological and pathological changes. Many prior studies have been limited to simulations of models containing single cells, which may not accurately describe the influence of mechanical interactions between cells. It is desirable to generate models that more accurately reflect the cellular organisation in tissue in order to evaluate the mechanical function of cells. However, as the model geometry becomes more complicated, manual model generation can become laborious. This can be prohibitive if a large number of distinct cell-scale models are required, for example, in multiscale modelling or probabilistic analysis. Therefore, a method was developed to automatically generate tissue-specific cellular models of arbitrary complexity, with minimal user intervention. This was achieved through a set of scripts, which are capable of generating both sample-specific models, with explicitly defined geometry, and tissue-specific models, with geometry derived implicitly from normal statistical distributions. Models are meshed with tetrahedral (TET) elements of variable size to sufficiently discretise model geometries at different spatial scales while reducing model complexity. The ability of TET meshes to appropriately simulate the biphasic mechanical response of a single-cell model is established against that of a corresponding hexahedral mesh for an illustrative use case. To further demonstrate the flexibility of this tool, an explicit model was developed from three-dimensional confocal laser scanning image data, and a set of models were generated from a statistical cellular distribution of the articular femoral cartilage. The tools presented herein are free and openly accessible to the community at large.
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Affiliation(s)
- Craig J Bennetts
- a Computational Biomodeling (CoBi) Core, Department of Biomedical Engineering , Lerner Research Institute , Cleveland Clinic, Cleveland , OH 44195 , USA
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16
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Sanchez-Adams J, Wilusz RE, Guilak F. Atomic force microscopy reveals regional variations in the micromechanical properties of the pericellular and extracellular matrices of the meniscus. J Orthop Res 2013; 31:1218-25. [PMID: 23568545 PMCID: PMC4037160 DOI: 10.1002/jor.22362] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 03/07/2013] [Indexed: 02/04/2023]
Abstract
Regional variations in the composition and architecture of the extracellular matrix (ECM) and pericellular matrix (PCM) of the knee meniscus play important roles in determining the local mechanical environment of meniscus cells. In this study, atomic force microscopy was used to spatially map the mechanical properties of matched ECM and perlecan-labeled PCM sites within the outer, middle, and inner porcine medial meniscus, and to evaluate the properties of the proximal surface of each region. The elastic modulus of the PCM was significantly higher in the outer region (151.4 ± 38.2 kPa) than the inner region (27.5 ± 8.8 kPa), and ECM moduli were consistently higher than region-matched PCM sites in both the outer (320.8 ± 92.5 kPa) and inner (66.1 ± 31.4 kPa) regions. These differences were associated with a higher proportion of aligned collagen fibers and lower glycosaminoglycan content in the outer region. Regional variations in the elastic moduli and some viscoelastic properties were observed on the proximal surface of the meniscus, with the inner region exhibiting the highest moduli overall. These results indicate that matrix architecture and composition play an important role in the regional micromechanical properties of the meniscus, suggesting that the local stress-strain environment of meniscal cells may vary significantly among the different regions.
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Affiliation(s)
- Johannah Sanchez-Adams
- Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC, United States
| | - Rebecca E. Wilusz
- Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC, United States,Department of Biomedical Engineering, Duke University, Durham, NC, United States
| | - Farshid Guilak
- Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC, United States,Department of Biomedical Engineering, Duke University, Durham, NC, United States,Corresponding Author: 375 Medical Sciences Research Bldg., Box 3093 DUMC, Durham, NC 27710 Phone: 919-684-2521 Fax: 919-681-8490
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Sibole SC, Maas S, Halloran JP, Weiss JA, Erdemir A. Evaluation of a post-processing approach for multiscale analysis of biphasic mechanics of chondrocytes. Comput Methods Biomech Biomed Engin 2013; 16:1112-26. [PMID: 23809004 DOI: 10.1080/10255842.2013.809711] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Understanding the mechanical behaviour of chondrocytes as a result of cartilage tissue mechanics has significant implications for both evaluation of mechanobiological function and to elaborate on damage mechanisms. A common procedure for prediction of chondrocyte mechanics (and of cell mechanics in general) relies on a computational post-processing approach where tissue-level deformations drive cell-level models. Potential loss of information in this numerical coupling approach may cause erroneous cellular-scale results, particularly during multiphysics analysis of cartilage. The goal of this study was to evaluate the capacity of first- and second-order data passing to predict chondrocyte mechanics by analysing cartilage deformations obtained for varying complexity of loading scenarios. A tissue-scale model with a sub-region incorporating representation of chondron size and distribution served as control. The post-processing approach first required solution of a homogeneous tissue-level model, results of which were used to drive a separate cell-level model (same characteristics as the sub-region of control model). The first-order data passing appeared to be adequate for simplified loading of the cartilage and for a subset of cell deformation metrics, for example, change in aspect ratio. The second-order data passing scheme was more accurate, particularly when asymmetric permeability of the tissue boundaries was considered. Yet, the method exhibited limitations for predictions of instantaneous metrics related to the fluid phase, for example, mass exchange rate. Nonetheless, employing higher order data exchange schemes may be necessary to understand the biphasic mechanics of cells under lifelike tissue loading states for the whole time history of the simulation.
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Affiliation(s)
- Scott C Sibole
- a Computational Biomodeling (CoBi) Core, Lerner Research Institute, Cleveland Clinic , Cleveland , OH , USA
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Effect of open wedge high tibial osteotomy on the lateral compartment in sheep. Part I: Analysis of the lateral meniscus. Knee Surg Sports Traumatol Arthrosc 2013; 21:39-48. [PMID: 22898914 DOI: 10.1007/s00167-012-2176-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 07/30/2012] [Indexed: 12/24/2022]
Abstract
PURPOSE To evaluate whether medial open wedge high tibial osteotomy (HTO) results in structural and biochemical changes in the lateral meniscus in adult sheep. METHODS Three experimental groups with biplanar osteotomies of the right proximal tibiae were tested: (a) closing wedge HTO resulting in 4.5° of tibial varus, (b) open wedge HTO resulting in 4.5° of tibial valgus (standard correction) and (c) open wedge HTO resulting in 9.5° of valgus (overcorrection), each of which was compared to the contralateral knees with normal limb axes. After 6 months, the lateral menisci were macroscopically and microscopically evaluated. The proteoglycan and DNA contents of the red-red and white-white zones of the anterior, middle and posterior third were determined. RESULTS Semiquantitative macroscopic and microscopic grading revealed no structural differences between groups. The red-red zone of the middle third of the lateral menisci of animals that underwent overcorrection exhibited a significant 0.7-fold decrease in mean DNA contents compared with the control knee without HTO (P = 0.012). Comparative estimation of the DNA and proteoglycan contents and proteoglycan/DNA ratios of all other parts and zones of the lateral menisci did not reveal significant differences between groups. CONCLUSION Open wedge HTO does not lead to significant macroscopic and microscopic structural changes in the lateral meniscus after 6 months in vivo. Overcorrection significantly decreases the proliferative activity of the cells in the red-red zone of the middle third in the sheep model.
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Sanchez-Adams J, Athanasiou KA. Biomechanics of meniscus cells: regional variation and comparison to articular chondrocytes and ligament cells. Biomech Model Mechanobiol 2012; 11:1047-56. [PMID: 22231673 DOI: 10.1007/s10237-012-0372-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 01/02/2012] [Indexed: 11/29/2022]
Abstract
Central to understanding mechanotransduction in the knee meniscus is the characterization of meniscus cell mechanics. In addition to biochemical and geometric differences, the inner and outer regions of the meniscus contain cells that are distinct in morphology and phenotype. This study investigated the regional variation in meniscus cell mechanics in comparison with articular chondrocytes and ligament cells. It was found that the meniscus contains two biomechanically distinct cell populations, with outer meniscus cells being stiffer (1.59 ± 0.19 kPa) than inner meniscus cells (1.07 ± 0.14 kPa). Additionally, it was found that both outer and inner meniscus cell stiffnesses were similar to ligament cells (1.32 ± 0.20 kPa), and articular chondrocytes showed the highest stiffness overall (2.51 ± 0.20 kPa). Comparison of compressibility characteristics of the cells showed similarities between articular chondrocytes and inner meniscus cells, as well as between outer meniscus cells and ligament cells. These results show that cellular biomechanics vary regionally in the knee meniscus and that meniscus cells are biomechanically similar to ligament cells. The mechanical properties of musculoskeletal cells determined in this study may be useful for the development of mathematical models or the design of experiments studying mechanotransduction in a variety of soft tissues.
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Yang PJ, Temenoff JS. Engineering orthopedic tissue interfaces. TISSUE ENGINEERING PART B-REVIEWS 2010; 15:127-41. [PMID: 19231983 DOI: 10.1089/ten.teb.2008.0371] [Citation(s) in RCA: 190] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
While a wide variety of approaches to engineering orthopedic tissues have been proposed, less attention has been paid to the interfaces, the specialized areas that connect two tissues of different biochemical and mechanical properties. The interface tissue plays an important role in transitioning mechanical load between disparate tissues. Thus, the relatively new field of interfacial tissue engineering presents new challenges--to not only consider the regeneration of individual orthopedic tissues, but also to design the biochemical and cellular composition of the linking tissue. Approaches to interfacial tissue engineering may be distinguished based on if the goal is to recreate the interface itself, or generate an entire integrated tissue unit (such as an osteochondral plug). As background for future efforts in engineering orthopedic interfaces, a brief review of the biology and mechanics of each interface (cartilage-bone, ligament-bone, meniscus-bone, and muscle-tendon) is presented, followed by an overview of the state-of-the-art in engineering each tissue, including advances and challenges specific to regenerating the interfaces.
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Affiliation(s)
- Peter J Yang
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332, USA
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Three-dimensional finite element modeling of pericellular matrix and cell mechanics in the nucleus pulposus of the intervertebral disk based on in situ morphology. Biomech Model Mechanobiol 2010; 10:1-10. [PMID: 20376522 DOI: 10.1007/s10237-010-0214-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Accepted: 03/19/2010] [Indexed: 10/19/2022]
Abstract
Nucleus pulposus (NP) cells of the intervertebral disk (IVD) have unique morphological characteristics and biologic responses to mechanical stimuli that may regulate maintenance and health of the IVD. NP cells reside as single cell, paired or multiple cells in a contiguous pericellular matrix (PCM), whose structure and properties may significantly influence cell and extracellular matrix mechanics. In this study, a computational model was developed to predict the stress-strain, fluid pressure and flow fields for cells and their surrounding PCM in the NP using three-dimensional (3D) finite element models based on the in situ morphology of cell-PCM regions of the mature rat NP, measured using confocal microscopy. Three-dimensional geometries of the extracellular matrix and representative cell-matrix units were used to construct 3D finite element models of the structures as isotropic and biphasic materials. In response to compressive strain of the extracellular matrix, NP cells and PCM regions were predicted to experience volumetric strains that were 1.9-3.7 and 1.4-2.1 times greater than the extracellular matrix, respectively. Volumetric and deviatoric strain concentrations were generally found at the cell/PCM interface, while von Mises stress concentrations were associated with the PCM/extracellular matrix interface. Cell-matrix units containing greater cell numbers were associated with higher peak cell strains and lower rates of fluid pressurization upon loading. These studies provide new model predictions for micromechanics of NP cells that can contribute to an understanding of mechanotransduction in the IVD and its changes with aging and degeneration.
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22
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Mechanical injury of explants from the articulating surface of the inner meniscus. Arch Biochem Biophys 2010; 494:138-44. [DOI: 10.1016/j.abb.2009.11.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2009] [Revised: 11/17/2009] [Accepted: 11/18/2009] [Indexed: 11/21/2022]
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Wilson CG, Vanderploeg EJ, Zuo F, Sandy JD, Levenston ME. Aggrecanolysis and in vitro matrix degradation in the immature bovine meniscus: mechanisms and functional implications. Arthritis Res Ther 2009; 11:R173. [PMID: 19919704 PMCID: PMC3003508 DOI: 10.1186/ar2862] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 10/16/2009] [Accepted: 11/17/2009] [Indexed: 11/21/2022] Open
Abstract
Introduction Little is known about endogenous or cytokine-stimulated aggrecan catabolism in the meniscal fibrocartilage of the knee. The objectives of this study were to characterize the structure, distribution, and processing of aggrecan in menisci from immature bovines, and to identify mechanisms of extracellular matrix degradation that lead to changes in the mechanical properties of meniscal fibrocartilage. Methods Aggrecanase activity in the native immature bovine meniscus was examined by immunolocalization of the aggrecan NITEGE neoepitope. To investigate mechanisms of cytokine-induced aggrecan catabolism in this tissue, explants were treated with interleukin-1α (IL-1) in the absence or presence of selective or broad spectrum metalloproteinase inhibitors. The sulfated glycosaminoglycan (sGAG) and collagen contents of explants and culture media were quantified by biochemical methods, and aggrecan catabolism was examined by Western analysis of aggrecan fragments. The mechanical properties of explants were determined by dynamic compression and shear tests. Results The aggrecanase-generated NITEGE neoepitope was preferentially localized in the middle and outer regions of freshly isolated immature bovine menisci, where sGAG density was lowest and blood vessels were present. In vitro treatment of explants with IL-1 triggered the accumulation of NITEGE in the inner and middle regions. Middle region explants stimulated with IL-1 exhibited substantial decreases in sGAG content, collagen content, and mechanical properties. A broad spectrum metalloproteinase inhibitor significantly reduced sGAG loss, abrogated collagen degradation, and preserved tissue mechanical properties. In contrast, an inhibitor selective for ADAMTS-4 and ADAMTS-5 was least effective at blocking IL-1-induced matrix catabolism and loss of mechanical properties. Conclusions Aggrecanase-mediated aggrecanolysis, typical of degenerative articular cartilage, may play a physiologic role in the development of the immature bovine meniscus. IL-1-induced release of sGAG and loss of mechanical properties can be ascribed primarily to the activity of MMPs or aggrecanases other than ADAMTS-4 and ADAMTS-5. These results may have implications for the clinical management of osteoarthritis.
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Affiliation(s)
- Christopher G Wilson
- Wallace H Coulter Department of Biomedical Engineering, 313 Ferst Drive, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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Cao L, Guilak F, Setton LA. Pericellular Matrix Mechanics in the Anulus Fibrosus Predicted by a Three-Dimensional Finite Element Model and In Situ Morphology. Cell Mol Bioeng 2009; 2:306-319. [PMID: 19946619 DOI: 10.1007/s12195-009-0081-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Anulus fibrosus (AF) cells have been demonstrated to exhibit dramatic differences in morphology and biologic responses to different types of mechanical stimuli. AF cells may reside as single cell, paired or multiple cells in a contiguous pericellular matrix (PCM), whose structure and properties are expected to have a significant influence on the mechanical stimuli that these cells may experience during physiologic loading of the spine, as well as in tissue degeneration and regeneration. In this study, a computational model was developed to predict the micromechanical stimuli, such as stress and strain, fluid pressure and flow, of cells and their surrounding PCM in the AF tissue using three-dimensional (3D) finite element models based on in situ morphology. 3D solid geometries of cell-PCM regions were registered from serial confocal images obtained from mature rat AF tissues by custom codes. Distinct cell-matrix units were modeled with a custom 3D biphasic finite element code (COMSOL Multiphysics), and simulated to experience uni-axial tensile strain along the local collagen fiber direction. AF cells were predicted to experience higher volumetric strain with a strain amplification ratio (relative to that in the extracellular matrix) of ~ 3.1 - 3.8 at equilibrium, as compared to the PCM domains (1.3 - 1.9). The strain concentrations were generally found at the cell/PCM interface and stress concentration at the PCM/ECM interface. Increased numbers of cells within a contiguous PCM was associated with an apparent increase of strain levels and decreased rate of fluid pressurization in the cell, with magnitudes dependent on the cell size, shape and relative position inside the PCM. These studies provide spatio-temporal information on micromechanics of AF cells in understanding the mechanotransduction in the intervertebral disc.
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Affiliation(s)
- Li Cao
- Departments of Biomedical Engineering and Surgery Duke University Durham, North Carolina 27710
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Sanchez-Adams J, Athanasiou KA. The Knee Meniscus: A Complex Tissue of Diverse Cells. Cell Mol Bioeng 2009. [DOI: 10.1007/s12195-009-0066-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Transfer of macroscale tissue strain to microscale cell regions in the deformed meniscus. Biophys J 2008; 95:2116-24. [PMID: 18487290 DOI: 10.1529/biophysj.107.126938] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cells within fibrocartilaginous tissues, including chondrocytes and fibroblasts of the meniscus, ligament, and tendon, regulate cell biosynthesis in response to local mechanical stimuli. The processes by which an applied mechanical load is transferred through the extracellular matrix to the environment of a cell are not fully understood. To better understand the role of mechanics in controlling cell phenotype and biosynthetic activity, this study was conducted to measure strain at different length scales in tissue of the fibrocartilaginous meniscus of the knee joint, and to define a quantitative parameter that describes the strain transferred from the far-field tissue to a microenvironment surrounding a cell. Experiments were performed to apply a controlled uniaxial tensile deformation to explants of porcine meniscus containing live cells. Using texture correlation analyses of confocal microscopy images, two-dimensional Lagrangian and principal strains were measured at length scales representative of the tissue (macroscale) and microenvironment in the region of a cell (microscale) to yield a strain transfer ratio as a measure of median microscale to macroscale strain. The data demonstrate that principal strains at the microscale are coupled to and amplified from macroscale principal strains for a majority of cell microenvironments located across diverse microstructural regions, with average strain transfer ratios of 1.6 and 2.9 for the maximum and minimum principal strains, respectively. Lagrangian strain components calculated along the experimental axes of applied deformations exhibited considerable spatial heterogeneity and intersample variability, and suggest the existence of both strain amplification and attenuation. This feature is consistent with an in-plane rotation of the principal strain axes relative to the experimental axes at the microscale that may result from fiber sliding, fiber twisting, and fiber-matrix interactions that are believed to be important for regulating deformation in other fibrocartilaginous tissues. The findings for consistent amplification of macroscale to microscale principal strains suggest a coordinated pattern of strain transfer from applied deformation to the microscale environment of a cell that is largely independent of these microstructural features in the fibrocartilaginous meniscus.
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Pham A, Hull ML. Dehydration rates of meniscus and articular cartilage in vitro using a fast and accurate laser-based coordinate digitizing system. J Biomech 2007; 40:3223-9. [PMID: 17568591 DOI: 10.1016/j.jbiomech.2007.04.015] [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] [Received: 03/15/2007] [Revised: 04/27/2007] [Accepted: 04/27/2007] [Indexed: 11/26/2022]
Abstract
When used in in vitro studies, soft tissues such as the meniscus and articular cartilage are susceptible to dehydration and its effects, such as changes in size and shape as well as changes in structural and material properties. To quantify the effect of dehydration on the meniscus and articular cartilage, the first two objectives of this study were to (1) determine the percent change in meniscal dimensions over time due to dehydration, and (2) determine the percent change in articular cartilage thickness due to dehydration. To satisfy these two objectives, the third objective was to develop a new laser-based three-dimensional coordinate digitizing system (3-DCDS II) that can scan either the meniscus or articular cartilage surface within a time such that there is less than a 5% change in measurements due to dehydration. The new instrument was used to measure changes in meniscal and articular cartilage dimensions of six cadaveric specimens, which were exposed to air for 120 and 130 min, respectively. While there was no change in meniscal width, meniscal height decreased linearly by 4.5% per hour. Articular cartilage thickness decreased nonlinearly at a rate of 6% per hour after 10 min, and at a rate of 16% per hour after 130 min. The system bias and precision of the new instrument at 0 degrees slope of the surface being scanned were 0.0 and 2.6 microm, respectively, while at 45 degrees slope the bias and precision were 31.1 and 22.6 microm, respectively. The resolution ranged between 200 and 500 microm. Scanning an area of 60 x 80 mm (approximately the depth and width of a human tibial plateau) took 8 min and a complete scan of all five sides of a meniscus took 24 min. Thus, the 3-DCDS II can scan an entire meniscus with less than 2% change in dimensions due to dehydration and articular cartilage with less than 0.4% change. This study provides new information on the amount of time that meniscal tissue and articular cartilage can be exposed to air before marked changes in size and shape, and possibly biomechanical, structural and material properties, occur. The new 3-DCDS II designed for this study provides fast and accurate dimensional measurements of both soft and hard tissues.
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Affiliation(s)
- An Pham
- Department of Mechanical Engineering, One Shields Avenue, University of California, Davis, CA 95616, USA
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Hennerbichler A, Fermor B, Hennerbichler D, Weinberg JB, Guilak F. Regional differences in prostaglandin E2 and nitric oxide production in the knee meniscus in response to dynamic compression. Biochem Biophys Res Commun 2007; 358:1047-53. [PMID: 17517372 PMCID: PMC2258009 DOI: 10.1016/j.bbrc.2007.05.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Accepted: 05/06/2007] [Indexed: 11/21/2022]
Abstract
Injury or loss of the knee meniscus is associated with altered joint stresses that lead to progressive joint degeneration. The goal of this study was to determine if dynamic mechanical compression influences the production of inflammatory mediators by meniscal cells. Dynamic compression increased prostaglandin E2 (PGE(2)) and nitric oxide (NO) production over a range of stress magnitudes (0.0125-0.5 MPa) in a manner that depended on stress magnitude and zone of tissue origin. Inner zone explants showed greater increases in PGE(2) and NO production as compared to outer zone explants. Meniscal tissue expressed NOS2 and NOS3 protein, but not NOS1. Mechanically induced NO production was blocked by NOS inhibitors, and the non-selective NOS inhibitor L-NMMA augmented PGE(2) production in the outer zone only. These findings suggest that the meniscus may serve as an intra-articular source of pro-inflammatory mediators, and that alterations in the magnitude or distribution of joint loading could significantly influence the production of these mediators in vivo.
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Affiliation(s)
- Alfred Hennerbichler
- Department of Surgery, Division of Orthopaedic Surgery, Duke University Medical Center, Durham, NC 27710, U.S.A
- Department of Trauma Surgery and Sports Medicine, Innsbruck Medical University, A-6020 Innsbruck, Austria
| | - Beverley Fermor
- Department of Surgery, Division of Orthopaedic Surgery, Duke University Medical Center, Durham, NC 27710, U.S.A
| | - Diana Hennerbichler
- Department of Surgery, Division of Orthopaedic Surgery, Duke University Medical Center, Durham, NC 27710, U.S.A
| | - J. Brice Weinberg
- Department of Medicine, VA and Duke Medical Centers, Durham, NC 27705, U.S.A
| | - Farshid Guilak
- Department of Surgery, Division of Orthopaedic Surgery, Duke University Medical Center, Durham, NC 27710, U.S.A
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Hennerbichler A, Moutos FT, Hennerbichler D, Weinberg JB, Guilak F. Repair response of the inner and outer regions of the porcine meniscus in vitro. Am J Sports Med 2007; 35:754-62. [PMID: 17261570 DOI: 10.1177/0363546506296416] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND The menisci are essential intra-articular structures that contribute to knee function, and meniscal injury or loss is associated with joint degeneration. Tears of the outer vascularized zone have a greater potential for repair than do tears in the inner avascular region. OBJECTIVE AND HYPOTHESIS Develop an in vitro explant model to examine the hypothesis that differences exist in the intrinsic repair response between the outer and inner region of the meniscus. STUDY DESIGN Controlled laboratory study. METHODS Cylindrical explants were harvested from the outer one third and inner two thirds of medial porcine menisci. To simulate a full-thickness defect, a central core was removed and reinserted immediately. Explants were cultured for 2, 4, or 6 weeks, and meniscal healing was investigated using mechanical testing, histologic analysis, and fluorescence confocal microscopy. RESULTS Over the 6-week culture period, meniscal explants exhibited migration of cells into the repair site, followed by increased tissue formation that bridged the interface. The repair strength increased significantly over time, with no differences between the 2 regions. CONCLUSION The findings show that explants from the avascular inner zone and vascular outer zone of the meniscus exhibit similar healing potential and repair strength in vitro. CLINICAL RELEVANCE These findings support the hypothesis that the regional differences in meniscal repair observed clinically are owed to the additional vascular supply of the outer meniscus rather than intrinsic differences between the extracellular matrix and cells from these 2 areas.
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Affiliation(s)
- Alfred Hennerbichler
- Department of Surgery, Division of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina 27710, USA
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Choi JB, Youn I, Cao L, Leddy HA, Gilchrist CL, Setton LA, Guilak F. Zonal changes in the three-dimensional morphology of the chondron under compression: the relationship among cellular, pericellular, and extracellular deformation in articular cartilage. J Biomech 2007; 40:2596-603. [PMID: 17397851 PMCID: PMC2265315 DOI: 10.1016/j.jbiomech.2007.01.009] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2006] [Accepted: 01/04/2007] [Indexed: 10/23/2022]
Abstract
The pericellular matrix (PCM) is a narrow region of tissue that completely surrounds chondrocytes in articular cartilage. Previous theoretical models of the "chondron" (the PCM with enclosed cells) suggest that the structure and properties of the PCM may significantly influence the mechanical environment of the chondrocyte. The objective of this study was to quantify changes in the three-dimensional (3D) morphology of the chondron in situ at different magnitudes of compression applied to the cartilage extracellular matrix. Fluorescence immunolabeling for type-VI collagen was used to identify the boundaries of the cell and PCM, and confocal microscopy was used to form 3D images of chondrons from superficial, middle, and deep zone cartilage in explants compressed to 0%, 10%, 30%, and 50% surface-to-surface strain. Lagrangian tissue strain, determined locally using texture correlation, was highly inhomogeneous and revealed depth-dependent compressive stiffness and Poisson's ratio of the extracellular matrix. Compression significantly decreased cell and chondron height and volume, depending on the zone and magnitude of compression. In the superficial zone, cellular-level strains were always lower than tissue-level strains. In the middle and deep zones, however, tissue strains below 25% were amplified at the cellular level, while tissue strains above 25% were decreased at the cellular level. These findings are consistent with previous theoretical models of the chondron, suggesting that the PCM can serve as either a protective layer for the chondrocyte or a transducer that amplifies strain, such that cellular-level strains are more homogenous throughout the tissue depth despite large inhomogeneities in local ECM strains.
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Affiliation(s)
- Jae Bong Choi
- Departments of Surgery and Biomedical Engineering Duke University Medical Center Durham, North Carolina 27710
- Department of Mechanical Systems Engineering Hansung University, Seoul, Korea
| | - Inchan Youn
- Departments of Surgery and Biomedical Engineering Duke University Medical Center Durham, North Carolina 27710
| | - Li Cao
- Departments of Surgery and Biomedical Engineering Duke University Medical Center Durham, North Carolina 27710
| | - Holly A. Leddy
- Departments of Surgery and Biomedical Engineering Duke University Medical Center Durham, North Carolina 27710
| | - Christopher L. Gilchrist
- Departments of Surgery and Biomedical Engineering Duke University Medical Center Durham, North Carolina 27710
| | - Lori A. Setton
- Departments of Surgery and Biomedical Engineering Duke University Medical Center Durham, North Carolina 27710
| | - Farshid Guilak
- Departments of Surgery and Biomedical Engineering Duke University Medical Center Durham, North Carolina 27710
- *Corresponding author: Farshid Guilak, Ph.D., Orthopaedic Research Laboratories, Department of Surgery, Division of Orthopaedic Surgery, 375 MSRB, Box 3093, Duke University Medical Center, Durham, North Carolina 27710, Phone: (919) 684-2521, Fax: (919) 681-8490, E-mail:
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Youn I, Choi JB, Cao L, Setton LA, Guilak F. Zonal variations in the three-dimensional morphology of the chondron measured in situ using confocal microscopy. Osteoarthritis Cartilage 2006; 14:889-97. [PMID: 16626979 DOI: 10.1016/j.joca.2006.02.017] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Accepted: 02/28/2006] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Chondrocytes in articular cartilage are surrounded by a narrow pericellular matrix (PCM), which together with the enclosed cell(s) are termed the "chondron". Although the precise function of this tissue region is unknown, previous studies provide indirect evidence that the PCM plays an important role in governing the local mechanical environment of chondrocytes. In particular, theoretical models of the chondron under mechanical loading suggest that the shape, size, and biomechanical properties of the PCM significantly influence the stress-strain and fluid flow environment of the cell. The goal of this study was to quantify the three-dimensional morphology of chondron in situ using en bloc immunolabeling of type VI collagen coupled with fluorescence confocal microscopy. METHODS Three-dimensional reconstructions of intact, fluorescently labeled chondrons were made from stacks of confocal images recorded in situ from the superficial, middle, and deep zones of porcine articular cartilage of the medial femoral condyle. RESULTS Significant variations in the shape, size, and orientation of chondrocytes and chondrons were observed with depth from the tissue surface, revealing flattened discoidal chondrons in the superficial zone, rounded chondrons in the middle zone, and elongated, multicellular chondrons in the deep zone. CONCLUSIONS The shape and orientation of the chondron appear to reflect the local collagen architecture of the interterritorial matrix, which varies significantly with depth. Quantitative measurements of morphology of the chondron and its variation with site, disease, or aging may provide new insights into the influence of this structure on physiology and the pathology of articular cartilage.
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Affiliation(s)
- I Youn
- Department of Surgery, Duke University Medical Center, Durham, NC 27710, USA
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