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Tissue engineering of the temporomandibular joint disc: current status and future trends. Int J Artif Organs 2015; 38:55-68. [PMID: 25744198 DOI: 10.5301/ijao.5000393] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2014] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Temporomandibular joint disorders are extremely prevalent and there is no ideal treatment clinically for the moment. For severe cases, a discectomy often need to be performed, which will further result in the development of osteoarthritis. In the past thirty years, tissue engineering has provided a promising approach for the effective remedy of severe TMJ disease through the creation of viable, effective, and biological functional implants. METHODS Although TMJ disc tissue engineering is still in early stage, unremitting efforts and some achievements have been made over the past decades. In this review, a comprehensive summary of the available literature on the progress and status in tissue engineering of the TMJ disc regarding cell sources, scaffolds, biochemical and biomechanical stimuli, and other prospects relative to this field is provided. RESULTS AND CONCLUSIONS Even though research studies in this field are too few compared to other fibrocartilage (e.g., knee meniscus) and numerous, difficult tasks still exist, we believe that our ultimate goal of regenerating a biological implant whose histological, biochemical, and biomechanical properties parallel native TMJ discs for clinical therapy will be achieved in the near future.
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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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103
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Athanasiou KA, Responte DJ, Brown WE, Hu JC. Harnessing biomechanics to develop cartilage regeneration strategies. J Biomech Eng 2015; 137:020901. [PMID: 25322349 DOI: 10.1115/1.4028825] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Indexed: 12/24/2022]
Abstract
As this review was prepared specifically for the American Society of Mechanical Engineers H.R. Lissner Medal, it primarily discusses work toward cartilage regeneration performed in Dr. Kyriacos A. Athanasiou's laboratory over the past 25 years. The prevalence and severity of degeneration of articular cartilage, a tissue whose main function is largely biomechanical, have motivated the development of cartilage tissue engineering approaches informed by biomechanics. This article provides a review of important steps toward regeneration of articular cartilage with suitable biomechanical properties. As a first step, biomechanical and biochemical characterization studies at the tissue level were used to provide design criteria for engineering neotissues. Extending this work to the single cell and subcellular levels has helped to develop biochemical and mechanical stimuli for tissue engineering studies. This strong mechanobiological foundation guided studies on regenerating hyaline articular cartilage, the knee meniscus, and temporomandibular joint (TMJ) fibrocartilage. Initial tissue engineering efforts centered on developing biodegradable scaffolds for cartilage regeneration. After many years of studying scaffold-based cartilage engineering, scaffoldless approaches were developed to address deficiencies of scaffold-based systems, resulting in the self-assembling process. This process was further improved by employing exogenous stimuli, such as hydrostatic pressure, growth factors, and matrix-modifying and catabolic agents, both singly and in synergistic combination to enhance neocartilage functional properties. Due to the high cell needs for tissue engineering and the limited supply of native articular chondrocytes, costochondral cells are emerging as a suitable cell source. Looking forward, additional cell sources are investigated to render these technologies more translatable. For example, dermis isolated adult stem (DIAS) cells show potential as a source of chondrogenic cells. The challenging problem of enhanced integration of engineered cartilage with native cartilage is approached with both familiar and novel methods, such as lysyl oxidase (LOX). These diverse tissue engineering strategies all aim to build upon thorough biomechanical characterizations to produce functional neotissue that ultimately will help combat the pressing problem of cartilage degeneration. As our prior research is reviewed, we look to establish new pathways to comprehensively and effectively address the complex problems of musculoskeletal cartilage regeneration.
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104
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Hadidi P, Yeh TC, Hu JC, Athanasiou KA. Critical seeding density improves the properties and translatability of self-assembling anatomically shaped knee menisci. Acta Biomater 2015; 11:173-82. [PMID: 25234157 DOI: 10.1016/j.actbio.2014.09.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 08/17/2014] [Accepted: 09/09/2014] [Indexed: 02/07/2023]
Abstract
A recent development in the field of tissue engineering is the rise of all-biologic, scaffold-free engineered tissues. Since these biomaterials rely primarily upon cells, investigation of initial seeding densities constitutes a particularly relevant aim for tissue engineers. In this study, a scaffold-free method was used to create fibrocartilage in the shape of the rabbit knee meniscus. The objectives of this study were to: (i) determine the minimum seeding density, normalized by an area of 44 mm(2), necessary for the self-assembling process of fibrocartilage to occur; (ii) examine relevant biomechanical properties of engineered fibrocartilage, such as tensile and compressive stiffness and strength, and their relationship to seeding density; and (iii) identify a reduced, or optimal, number of cells needed to produce this biomaterial. It was found that a decreased initial seeding density, normalized by the area of the construct, produced superior mechanical and biochemical properties. Collagen per wet weight, glycosaminoglycans per wet weight, tensile properties and compressive properties were all significantly greater in the 5 million cells per construct group as compared to the historical 20 million cells per construct group. Scanning electron microscopy demonstrated that a lower seeding density results in a denser tissue. Additionally, the translational potential of the self-assembling process for tissue engineering was improved though this investigation, as fewer cells may be used in the future. The results of this study underscore the potential for critical seeding densities to be investigated when researching scaffold-free engineered tissues.
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Affiliation(s)
- Pasha Hadidi
- Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Timothy C Yeh
- Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Jerry C Hu
- Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Kyriacos A Athanasiou
- Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA; Department of Orthopedic Surgery, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
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105
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Zhang ZZ, Jiang D, Wang SJ, Qi YS, Ding JX, Yu JK, Chen XS. Scaffolds drive meniscus tissue engineering. RSC Adv 2015. [DOI: 10.1039/c5ra13859k] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The review focuses on the recent research trend on scaffold types and biomedical applications, and perspectives in meniscus tissue engineering.
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Affiliation(s)
- Zheng-Zheng Zhang
- Institute of Sports Medicine
- Beijing Key Laboratory of Sports Injuries
- Peking University Third Hospital
- Beijing 100191
- P. R. China
| | - Dong Jiang
- Institute of Sports Medicine
- Beijing Key Laboratory of Sports Injuries
- Peking University Third Hospital
- Beijing 100191
- P. R. China
| | - Shao-Jie Wang
- Institute of Sports Medicine
- Beijing Key Laboratory of Sports Injuries
- Peking University Third Hospital
- Beijing 100191
- P. R. China
| | - Yan-Song Qi
- Institute of Sports Medicine
- Beijing Key Laboratory of Sports Injuries
- Peking University Third Hospital
- Beijing 100191
- P. R. China
| | - Jian-Xun Ding
- Key Laboratory of Polymer Ecomaterials
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- P. R. China
| | - Jia-Kuo Yu
- Institute of Sports Medicine
- Beijing Key Laboratory of Sports Injuries
- Peking University Third Hospital
- Beijing 100191
- P. R. China
| | - Xue-Si Chen
- Key Laboratory of Polymer Ecomaterials
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- P. R. China
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Makris EA, Huang BJ, Hu JC, Chen-Izu Y, Athanasiou KA. Digoxin and adenosine triphosphate enhance the functional properties of tissue-engineered cartilage. Tissue Eng Part A 2014; 21:884-94. [PMID: 25473799 DOI: 10.1089/ten.tea.2014.0360] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Toward developing engineered cartilage for the treatment of cartilage defects, achieving relevant functional properties before implantation remains a significant challenge. Various chemical and mechanical stimuli have been used to enhance the functional properties of engineered musculoskeletal tissues. Recently, Ca(2+)-modulating agents have been used to enhance matrix synthesis and biomechanical properties of engineered cartilage. The objective of this study was to determine whether other known Ca(2+) modulators, digoxin and adenosine triphosphate (ATP), can be employed as novel stimuli to increase collagen synthesis and functional properties of engineered cartilage. Neocartilage constructs were formed by scaffold-free self-assembling of primary bovine articular chondrocytes. Digoxin, ATP, or both agents were added to the culture medium for 1 h/day on days 10-14. After 4 weeks of culture, neocartilage properties were assessed for gross morphology, biochemical composition, and biomechanical properties. Digoxin and ATP were found to increase neocartilage collagen content by 52-110% over untreated controls, while maintaining proteoglycan content near native tissue values. Furthermore, digoxin and ATP increased the tensile modulus by 280% and 180%, respectively, while the application of both agents increased the modulus by 380%. The trends in tensile properties were found to correlate with the amount of collagen cross-linking. Live Ca(2+) imaging experiments revealed that both digoxin and ATP were able to increase Ca(2+) oscillations in monolayer-cultured chondrocytes. This study provides a novel approach toward directing neocartilage maturation and enhancing its functional properties using novel Ca(2+) modulators.
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Affiliation(s)
- Eleftherios A Makris
- 1 Department of Biomedical Engineering, University of California Davis , Davis, California
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Murphy MK, DuRaine GD, Reddi A, Hu JC, Athanasiou KA. Inducing articular cartilage phenotype in costochondral cells. Arthritis Res Ther 2014; 15:R214. [PMID: 24330640 PMCID: PMC3979093 DOI: 10.1186/ar4409] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 11/26/2013] [Indexed: 02/06/2023] Open
Abstract
INTRODUCTION Costochondral cells may be isolated with minimal donor site morbidity and are unaffected by pathologies of the diarthrodial joints. Identification of optimal exogenous stimuli will allow abundant and robust hyaline articular cartilage to be formed from this cell source. METHODS In a three factor, two level full factorial design, the effects of hydrostatic pressure (HP), transforming growth factor β1 (TGF-β1), and chondroitinase ABC (C-ABC), and all resulting combinations, were assessed in third passage expanded, redifferentiated costochondral cells. After 4 wks, the new cartilage was assessed for matrix content, superficial zone protein (SZP), and mechanical properties. RESULTS Hyaline articular cartilage was generated, demonstrating the presence of type II collagen and SZP, and the absence of type I collagen. TGF-β1 upregulated collagen synthesis by 175% and glycosaminoglycan synthesis by 75%, resulting in a nearly 200% increase in tensile and compressive moduli. C-ABC significantly increased collagen content, and fibril density and diameter, leading to a 125% increase in tensile modulus. Hydrostatic pressure increased fibril diameter by 30% and tensile modulus by 45%. Combining TGF-β1 with C-ABC synergistically increased collagen content by 300% and tensile strength by 320%, over control. No significant differences were observed between C-ABC/TGF-β1 dual treatment and HP/C-ABC/TGF-β1. CONCLUSIONS Employing biochemical, biophysical, and mechanical stimuli generated robust hyaline articular cartilage with a tensile modulus of 2 MPa and a compressive instantaneous modulus of 650 kPa. Using expanded, redifferentiated costochondral cells in the self-assembling process allows for recapitulation of robust mechanical properties, and induced SZP expression, key characteristics of functional articular cartilage.
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108
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Liu Y, Buckley CT, Almeida HV, Mulhall KJ, Kelly DJ. Infrapatellar fat pad-derived stem cells maintain their chondrogenic capacity in disease and can be used to engineer cartilaginous grafts of clinically relevant dimensions. Tissue Eng Part A 2014; 20:3050-62. [PMID: 24785365 PMCID: PMC4229863 DOI: 10.1089/ten.tea.2014.0035] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 04/25/2014] [Indexed: 12/27/2022] Open
Abstract
A therapy for regenerating large cartilaginous lesions within the articular surface of osteoarthritic joints remains elusive. While tissue engineering strategies such as matrix-assisted autologous chondrocyte implantation can be used in the repair of focal cartilage defects, extending such approaches to the treatment of osteoarthritis will require a number of scientific and technical challenges to be overcome. These include the identification of an abundant source of chondroprogenitor cells that maintain their chondrogenic capacity in disease, as well as the development of novel approaches to engineer scalable cartilaginous grafts that could be used to resurface large areas of damaged joints. In this study, it is first demonstrated that infrapatellar fat pad-derived stem cells (FPSCs) isolated from osteoarthritic (OA) donors possess a comparable chondrogenic capacity to FPSCs isolated from patients undergoing ligament reconstruction. In a further validation of their functionality, we also demonstrate that FPSCs from OA donors respond to the application of physiological levels of cyclic hydrostatic pressure by increasing aggrecan gene expression and the production of sulfated glycosaminoglycans. We next explored whether cartilaginous grafts could be engineered with diseased human FPSCs using a self-assembly or scaffold-free approach. After examining a range of culture conditions, it was found that continuous supplementation with both transforming growth factor-β3 (TGF-β3) and bone morphogenic protein-6 (BMP-6) promoted the development of tissues rich in proteoglycans and type II collagen. The final phase of the study sought to scale-up this approach to engineer cartilaginous grafts of clinically relevant dimensions (≥2 cm in diameter) by assembling FPSCs onto electrospun PLLA fiber membranes. Over 6 weeks in culture, it was possible to generate robust, flexible cartilage-like grafts of scale, opening up the possibility that tissues engineered using FPSCs derived from OA patients could potentially be used to resurface large areas of joint surfaces damaged by trauma or disease.
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Affiliation(s)
- Yurong Liu
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
- Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland
- Sports Surgery Clinic, Dublin, Ireland
| | - Conor Timothy Buckley
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
- Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland
| | - Henrique V. Almeida
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
- Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland
| | | | - Daniel John Kelly
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
- Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland
- Advanced Materials and Bioengineering Research (AMBER) Centre, Trinity College Dublin, Dublin, Ireland
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Developing functional musculoskeletal tissues through hypoxia and lysyl oxidase-induced collagen cross-linking. Proc Natl Acad Sci U S A 2014; 111:E4832-41. [PMID: 25349395 DOI: 10.1073/pnas.1414271111] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The inability to recapitulate native tissue biomechanics, especially tensile properties, hinders progress in regenerative medicine. To address this problem, strategies have focused on enhancing collagen production. However, manipulating collagen cross-links, ubiquitous throughout all tissues and conferring mechanical integrity, has been underinvestigated. A series of studies examined the effects of lysyl oxidase (LOX), the enzyme responsible for the formation of collagen cross-links. Hypoxia-induced endogenous LOX was applied in multiple musculoskeletal tissues (i.e., cartilage, meniscus, tendons, ligaments). Results of these studies showed that both native and engineered tissues are enhanced by invoking a mechanism of hypoxia-induced pyridinoline (PYR) cross-links via intermediaries like LOX. Hypoxia was shown to enhance PYR cross-linking 1.4- to 6.4-fold and, concomitantly, to increase the tensile properties of collagen-rich tissues 1.3- to 2.2-fold. Direct administration of exogenous LOX was applied in native cartilage and neocartilage generated using a scaffold-free, self-assembling process of primary chondrocytes. Exogenous LOX was found to enhance native tissue tensile properties 1.9-fold. LOX concentration- and time-dependent increases in PYR content (∼ 16-fold compared with controls) and tensile properties (approximately fivefold compared with controls) of neocartilage were also detected, resulting in properties on par with native tissue. Finally, in vivo subcutaneous implantation of LOX-treated neocartilage in nude mice promoted further maturation of the neotissue, enhancing tensile and PYR content approximately threefold and 14-fold, respectively, compared with in vitro controls. Collectively, these results provide the first report, to our knowledge, of endogenous (hypoxia-induced) and exogenous LOX applications for promoting collagen cross-linking and improving the tensile properties of a spectrum of native and engineered tissues both in vitro and in vivo.
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110
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Emergence of scaffold-free approaches for tissue engineering musculoskeletal cartilages. Ann Biomed Eng 2014; 43:543-54. [PMID: 25331099 DOI: 10.1007/s10439-014-1161-y] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 10/09/2014] [Indexed: 10/24/2022]
Abstract
This review explores scaffold-free methods as an additional paradigm for tissue engineering. Musculoskeletal cartilages-for example articular cartilage, meniscus, temporomandibular joint disc, and intervertebral disc-are characterized by low vascularity and cellularity, and are amenable to scaffold-free tissue engineering approaches. Scaffold-free approaches, particularly the self-assembling process, mimic elements of developmental processes underlying these tissues. Discussed are various scaffold-free approaches for musculoskeletal cartilage tissue engineering, such as cell sheet engineering, aggregation, and the self-assembling process, as well as the availability and variety of cells used. Immunological considerations are of particular importance as engineered tissues are frequently of allogeneic, if not xenogeneic, origin. Factors that enhance the matrix production and mechanical properties of these engineered cartilages are also reviewed, as the fabrication of biomimetically suitable tissues is necessary to replicate function and ensure graft survival in vivo. The concept of combining scaffold-free and scaffold-based tissue engineering methods to address clinical needs is also discussed. Inasmuch as scaffold-based musculoskeletal tissue engineering approaches have been employed as a paradigm to generate engineered cartilages with appropriate functional properties, scaffold-free approaches are emerging as promising elements of a translational pathway not only for musculoskeletal cartilages but for other tissues as well.
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111
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Paschos NK, Makris EA, Hu JC, Athanasiou KA. Topographic variations in biomechanical and biochemical properties in the ankle joint: an in vitro bovine study evaluating native and engineered cartilage. Arthroscopy 2014; 30:1317-26. [PMID: 25064757 DOI: 10.1016/j.arthro.2014.05.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 04/17/2014] [Accepted: 05/19/2014] [Indexed: 02/02/2023]
Abstract
PURPOSE The purposes of this study were to identify differences in the biomechanical and biochemical properties among the articulating surfaces of the ankle joint and to evaluate the functional and biological properties of engineered neocartilage generated using chondrocytes from different locations in the ankle joint. METHODS The properties of the different topographies within the ankle joint (tibial plafond, talar dome, and distal fibula) were evaluated in 28 specimens using 7 bovine ankles; the femoral condyle was used as a control. Chondrocytes from the same locations were used to form 28 neocartilage constructs by tissue engineering using an additional 7 bovine ankles. The functional properties of neocartilage were compared with native tissue values. RESULTS Articular cartilage from the tibial plafond, distal fibula, talar dome, and femoral condyle exhibited Young modulus values of 4.8 ± 0.5 MPa, 3.9 ± 0.1 MPa, 1.7 ± 0.2 MPa, and 4.0 ± 0.5 MPa, respectively. The compressive properties of the corresponding tissues were 370 ± 22 kPa, 242 ± 18 kPa, 255 ± 26 kPa, and 274 ± 18 kPa, respectively. The tibial plafond exhibited 3-fold higher tensile properties and 2-fold higher compressive and shear moduli compared with its articulating talar dome; the same disparity was observed in neocartilage. Similar trends were detected in biochemical data for both native and engineered tissues. CONCLUSIONS The cartilage properties of the various topographic locations within the ankle are significantly different. In particular, the opposing articulating surfaces of the ankle have significantly different biomechanical and biochemical properties. The disparity between tibial plafond and talar dome cartilage and chondrocytes warrants further evaluation in clinical studies to evaluate their exact role in the pathogenesis of ankle lesions. CLINICAL RELEVANCE Therapeutic modalities for cartilage lesions need to consider the exact topographic source of the cells or cartilage grafts used. Furthermore, the capacity of generating neocartilage implants from location-specific chondrocytes of the ankle joint may be used in the future as a tool for the treatment of chondral lesions.
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Affiliation(s)
- Nikolaos K Paschos
- Department of Biomedical Engineering, University of California, Davis, California, U.S.A.; Orthopaedic Sports Medicine Center of Ioannina, Department of Orthopaedic Surgery, University of Ioannina, Ioannina, Greece
| | - Eleftherios A Makris
- Department of Biomedical Engineering, University of California, Davis, California, U.S.A.; Department of Orthopedic Surgery and Musculoskeletal Trauma, University of Thessaly, Larisa, Greece
| | - Jerry C Hu
- Department of Biomedical Engineering, University of California, Davis, California, U.S.A
| | - Kyriacos A Athanasiou
- Department of Biomedical Engineering, University of California, Davis, California, U.S.A.; Department of Orthopaedic Surgery, Lawrence Ellison Center for Tissue Regeneration and Repair, School of Medicine, University of California, Davis, California, U.S.A..
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Nicolini AP, Carvalho RT, Dragone B, Lenza M, Cohen M, Ferretti M. Updates in biological therapies for knee injuries: full thickness cartilage defect. Curr Rev Musculoskelet Med 2014; 7:256-62. [PMID: 25012907 PMCID: PMC4596164 DOI: 10.1007/s12178-014-9226-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Full thickness cartilage defect might occur at different ages, but a focal defect is a major concern in the knee of young athletes. It causes impairment and does not heal by itself. Several techniques were described to treat symptomatic full thickness cartilage defect. Recently, several advances were described on the known techniques of microfracture, osteochondral allograft, cell therapy, and others. This article brings an update of current literature on these well-described techniques for full thickness cartilage defect.
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Affiliation(s)
- Alexandre Pedro Nicolini
- />Division of Orthopaedic Surgery, Hospital Israelita Albert Einstein, Avenida Albert Einstein, 627/701 - 3 Andar/Bloco A1, Morumbi, 05651-901 São Paulo, SP Brazil
- />Departamento de Ortopedia e Traumatologia, Universidade Federal de São Paulo, São Paulo, SP Brazil
| | - Rogerio Teixeira Carvalho
- />Departamento de Ortopedia e Traumatologia, Universidade Federal de São Paulo, São Paulo, SP Brazil
| | - Bruno Dragone
- />Departamento de Ortopedia e Traumatologia, Universidade Federal de São Paulo, São Paulo, SP Brazil
| | - Mario Lenza
- />Division of Orthopaedic Surgery, Hospital Israelita Albert Einstein, Avenida Albert Einstein, 627/701 - 3 Andar/Bloco A1, Morumbi, 05651-901 São Paulo, SP Brazil
- />Departamento de Ortopedia e Traumatologia, Universidade Federal de São Paulo, São Paulo, SP Brazil
| | - Moises Cohen
- />Departamento de Ortopedia e Traumatologia, Universidade Federal de São Paulo, São Paulo, SP Brazil
| | - Mario Ferretti
- />Division of Orthopaedic Surgery, Hospital Israelita Albert Einstein, Avenida Albert Einstein, 627/701 - 3 Andar/Bloco A1, Morumbi, 05651-901 São Paulo, SP Brazil
- />Departamento de Ortopedia e Traumatologia, Universidade Federal de São Paulo, São Paulo, SP Brazil
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113
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A Novel Through-Thickness Perfusion Bioreactor for the Generation of Scaffold-Free Tissue Engineered Cartilage. Processes (Basel) 2014. [DOI: 10.3390/pr2030658] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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114
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Mesallati T, Buckley CT, Kelly DJ. Engineering articular cartilage-like grafts by self-assembly of infrapatellar fat pad-derived stem cells. Biotechnol Bioeng 2014; 111:1686-98. [DOI: 10.1002/bit.25213] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Tariq Mesallati
- Trinity Centre for Bioengineering; Trinity Biomedical Sciences Institute; Trinity College Dublin; Dublin Ireland
- Department of Mechanical and Manufacturing Engineering; School of Engineering; Trinity College Dublin; Dublin Ireland
| | - Conor T. Buckley
- Trinity Centre for Bioengineering; Trinity Biomedical Sciences Institute; Trinity College Dublin; Dublin Ireland
- Department of Mechanical and Manufacturing Engineering; School of Engineering; Trinity College Dublin; Dublin Ireland
| | - Daniel J. Kelly
- Trinity Centre for Bioengineering; Trinity Biomedical Sciences Institute; Trinity College Dublin; Dublin Ireland
- Department of Mechanical and Manufacturing Engineering; School of Engineering; Trinity College Dublin; Dublin Ireland
- Advanced Materials and Bioengineering Research Centre (AMBER); Trinity College Dublin; Dublin Ireland
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115
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Kalpakci KN, Brown WE, Hu JC, Athanasiou KA. Cartilage tissue engineering using dermis isolated adult stem cells: the use of hypoxia during expansion versus chondrogenic differentiation. PLoS One 2014; 9:e98570. [PMID: 24867063 PMCID: PMC4035316 DOI: 10.1371/journal.pone.0098570] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 05/04/2014] [Indexed: 11/25/2022] Open
Abstract
Dermis isolated adult stem (DIAS) cells, a subpopulation of dermis cells capable of chondrogenic differentiation in the presence of cartilage extracellular matrix, are a promising source of autologous cells for tissue engineering. Hypoxia, through known mechanisms, has profound effects on in vitro chondrogenesis of mesenchymal stem cells and could be used to improve the expansion and differentiation processes for DIAS cells. The objective of this study was to build upon the mechanistic knowledge of hypoxia and translate it to tissue engineering applications to enhance chondrogenic differentiation of DIAS cells through exposure to hypoxic conditions (5% O2) during expansion and/or differentiation. DIAS cells were isolated and expanded in hypoxic (5% O2) or normoxic (20% O2) conditions, then differentiated for 2 weeks in micromass culture on chondroitin sulfate-coated surfaces in both environments. Monolayer cells were examined for proliferation rate and colony forming efficiency. Micromasses were assessed for cellular, biochemical, and histological properties. Differentiation in hypoxic conditions following normoxic expansion increased per cell production of collagen type II 2.3 fold and glycosaminoglycans 1.2 fold relative to continuous normoxic culture (p<0.0001). Groups expanded in hypoxia produced 51% more collagen and 23% more GAGs than those expanded in normoxia (p<0.0001). Hypoxia also limited cell proliferation in monolayer and in 3D culture. Collectively, these data show hypoxic differentiation following normoxic expansion significantly enhances chondrogenic differentiation of DIAS cells, improving the potential utility of these cells for cartilage engineering.
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Affiliation(s)
- Kerem N. Kalpakci
- Medtronic Spine & Biologics, Memphis, Tennessee, United States of America
| | - Wendy E. Brown
- UC Davis, Department of Biomedical Engineering, Davis, California, United States of America
| | - Jerry C. Hu
- UC Davis, Department of Biomedical Engineering, Davis, California, United States of America
| | - Kyriacos A. Athanasiou
- UC Davis, Department of Biomedical Engineering, Davis, California, United States of America
- * E-mail:
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DuRaine GD, Arzi B, Lee JK, Lee CA, Responte DJ, Hu JC, Athanasiou KA. Biomechanical evaluation of suture-holding properties of native and tissue-engineered articular cartilage. Biomech Model Mechanobiol 2014; 14:73-81. [PMID: 24848644 DOI: 10.1007/s10237-014-0589-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 04/22/2014] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to determine suture-holding properties of tissue-engineered neocartilage relative to native articular cartilage. To this end, suture pull-out strength was quantified for native articular cartilage and for neocartilages possessing various mechanical properties. Suture-holding properties were examined in vitro and in vivo. Neocartilage from bovine chondrocytes was engineered using two sets of exogenous stimuli, resulting in neotissue of different biochemical compositions. Compressive and tensile properties and glycosaminoglycan, collagen, and pyridinoline cross-link contents were assayed (study 1). Suture pull-out strength was compared between neocartilage constructs, and bovine and leporine native cartilage. Uniaxial pull-out test until failure was performed after passing 6-0 Vicryl through each tissue (study 2). Subsequently, neocartilage was implanted into a rabbit model to examine short-term suture-holding ability in vivo (study 3). Neocartilage glycosaminoglycan and collagen content per wet weight reached 4.55 ± 1.62% and 4.21 ± 0.77%, respectively. Tensile properties for neocartilage constructs reached 2.6 ± 0.77% MPa for Young's modulus and 1.39 ± 0.63 MPa for ultimate tensile strength. Neocartilage reached ~ 33% of suture pull-out strength of native articular cartilage. Neocartilage cross-link content reached 50% of native values, and suture pull-out strength correlated positively with cross-link content (R² = 0.74). Neocartilage sutured into rabbit osteochondral defects was successfully maintained for 3 weeks. This study shows that pyridinoline cross-links in neocartilage may be vital in controlling suture pull-out strength. Neocartilage produced in vitro with one-third of native tissue pull-out strength appears sufficient for construct suturing and retention in vivo.
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Affiliation(s)
- G D DuRaine
- Department of Biomedical Engineering, College of Engineering, University of California Davis, Davis One Shields Avenue, Davis, CA, 95616, USA
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117
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Makris EA, MacBarb RF, Paschos NK, Hu JC, Athanasiou KA. Combined use of chondroitinase-ABC, TGF-β1, and collagen crosslinking agent lysyl oxidase to engineer functional neotissues for fibrocartilage repair. Biomaterials 2014; 35:6787-96. [PMID: 24840619 DOI: 10.1016/j.biomaterials.2014.04.083] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 04/22/2014] [Indexed: 11/18/2022]
Abstract
Patients suffering from damaged or diseased fibrocartilages currently have no effective long-term treatment options. Despite their potential, engineered tissues suffer from inferior biomechanical integrity and an inability to integrate in vivo. The present study identifies a treatment regimen (including the biophysical agent chondroitinase-ABC, the biochemical agent TGF-β1, and the collagen crosslinking agent lysyl oxidase) to prime highly cellularized, scaffold-free neofibrocartilage implants, effecting continued improvement in vivo. We show these agents drive in vitro neofibrocartilage matrix maturation toward synergistically enhanced Young's modulus and ultimate tensile strength values, which were increased 245% and 186%, respectively, over controls. Furthermore, an in vitro fibrocartilage defect model found this treatment regimen to significantly increase the integration tensile properties between treated neofibrocartilage and native tissue. Through translating this technology to an in vivo fibrocartilage defect model, our results indicate, for the first time, that a pre-treatment can prime neofibrocartilage for significantly enhanced integration potential in vivo, with interfacial tensile stiffness and strength increasing by 730% and 745%, respectively, compared to integration values achieved in vitro. Our results suggest that specifically targeting collagen assembly and organization is a powerful means to augment overall neotissue mechanics and integration potential toward improved clinical feasibility.
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Affiliation(s)
- Eleftherios A Makris
- Department of Biomedical Engineering, University of California Davis, United States; Department of Orthopaedic Surgery and Musculoskeletal Trauma, University of Thessaly, Greece
| | - Regina F MacBarb
- Department of Biomedical Engineering, University of California Davis, United States
| | - Nikolaos K Paschos
- Department of Biomedical Engineering, University of California Davis, United States
| | - Jerry C Hu
- Department of Biomedical Engineering, University of California Davis, United States
| | - Kyriacos A Athanasiou
- Department of Biomedical Engineering, University of California Davis, United States; Department of Orthopaedic Surgery, University of California Davis, United States.
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118
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Murphy MK, MacBarb RF, Wong ME, Athanasiou KA. Temporomandibular disorders: a review of etiology, clinical management, and tissue engineering strategies. Int J Oral Maxillofac Implants 2014; 28:e393-414. [PMID: 24278954 DOI: 10.11607/jomi.te20] [Citation(s) in RCA: 198] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Temporomandibular disorders (TMD) are a class of degenerative musculoskeletal conditions associated with morphologic and functional deformities that affect up to 25% of the population, but their etiology and progression are poorly understood and, as a result, treatment options are limited. In up to 70% of cases, TMD are accompanied by malpositioning of the temporomandibular joint (TMJ) disc, termed "internal derangement." Although the onset is not well characterized, correlations between internal derangement and osteoarthritic change have been identified. Because of the complex and unique nature of each TMD case, diagnosis requires patient-specific analysis accompanied by various diagnostic modalities. Likewise, treatment requires customized plans to address the specific characteristics of each patient's disease. In the mechanically demanding and biochemically active environment of the TMJ, therapeutic approaches that can restore joint functionality while responding to changes in the joint have become a necessity. One such approach, tissue engineering, which may be capable of integration and adaptation in the TMJ, carries significant potential for the development of repair and replacement tissues. The following review presents a synopsis of etiology, current treatment methods, and the future of tissue engineering for repairing and/or replacing diseased joint components, specifically the mandibular condyle and TMJ disc. An analysis of native tissue characterization to assist clinicians in identifying tissue engineering objectives and validation metrics for restoring healthy and functional structures of the TMJ is followed by a discussion of current trends in tissue engineering.
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119
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Large, stratified, and mechanically functional human cartilage grown in vitro by mesenchymal condensation. Proc Natl Acad Sci U S A 2014; 111:6940-5. [PMID: 24778247 DOI: 10.1073/pnas.1324050111] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The efforts to grow mechanically functional cartilage from human mesenchymal stem cells have not been successful. We report that clinically sized pieces of human cartilage with physiologic stratification and biomechanics can be grown in vitro by recapitulating some aspects of the developmental process of mesenchymal condensation. By exposure to transforming growth factor-β, mesenchymal stem cells were induced to condense into cellular bodies, undergo chondrogenic differentiation, and form cartilagenous tissue, in a process designed to mimic mesenchymal condensation leading into chondrogenesis. We discovered that the condensed mesenchymal cell bodies (CMBs) formed in vitro set an outer boundary after 5 d of culture, as indicated by the expression of mesenchymal condensation genes and deposition of tenascin. Before setting of boundaries, the CMBs could be fused into homogenous cellular aggregates giving rise to well-differentiated and mechanically functional cartilage. We used the mesenchymal condensation and fusion of CMBs to grow centimeter-sized, anatomically shaped pieces of human articular cartilage over 5 wk of culture. For the first time to our knowledge biomechanical properties of cartilage derived from human mesenchymal cells were comparable to native cartilage, with the Young's modulus of >800 kPa and equilibrium friction coeffcient of <0.3. We also demonstrate that CMBs have capability to form mechanically strong cartilage-cartilage interface in an in vitro cartilage defect model. The CMBs, which acted as "lego-like" blocks of neocartilage, were capable of assembling into human cartilage with physiologic-like structure and mechanical properties.
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120
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Paschos NK, Brown WE, Eswaramoorthy R, Hu JC, Athanasiou KA. Advances in tissue engineering through stem cell-based co-culture. J Tissue Eng Regen Med 2014; 9:488-503. [PMID: 24493315 DOI: 10.1002/term.1870] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 12/19/2013] [Accepted: 01/03/2014] [Indexed: 12/13/2022]
Abstract
Stem cells are the future in tissue engineering and regeneration. In a co-culture, stem cells not only provide a target cell source with multipotent differentiation capacity, but can also act as assisting cells that promote tissue homeostasis, metabolism, growth and repair. Their incorporation into co-culture systems seems to be important in the creation of complex tissues or organs. In this review, critical aspects of stem cell use in co-culture systems are discussed. Direct and indirect co-culture methodologies used in tissue engineering are described, along with various characteristics of cellular interactions in these systems. Direct cell-cell contact, cell-extracellular matrix interaction and signalling via soluble factors are presented. The advantages of stem cell co-culture strategies and their applications in tissue engineering and regenerative medicine are portrayed through specific examples for several tissues, including orthopaedic soft tissues, bone, heart, vasculature, lung, kidney, liver and nerve. A concise review of the progress and the lessons learned are provided, with a focus on recent developments and their implications. It is hoped that knowledge developed from one tissue can be translated to other tissues. Finally, we address challenges in tissue engineering and regenerative medicine that can potentially be overcome via employing strategies for stem cell co-culture use.
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Affiliation(s)
- Nikolaos K Paschos
- Department of Biomedical Engineering and Orthopedic Surgery, University of California at Davis, CA, 95616, USA
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121
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Murphy MK, Masters TE, Hu JC, Athanasiou KA. Engineering a fibrocartilage spectrum through modulation of aggregate redifferentiation. Cell Transplant 2013; 24:235-45. [PMID: 24380383 DOI: 10.3727/096368913x676204] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Expanded costochondral cells provide a clinically relevant cell source for engineering both fibrous and hyaline articular cartilage. Expanding chondrocytes in a monolayer results in a shift toward a proliferative, fibroblastic phenotype. Three-dimensional aggregate culture may, however, be used to recover chondrogenic matrix production. This study sought to engineer a spectrum of fibrous to hyaline neocartilage from a single cell source by varying the duration of three-dimensional culture following expansion. In third passage porcine costochondral cells, the effects of aggregate culture duration were assessed after 0, 8, 11, 14, and 21 days of aggregate culture and after 4 subsequent weeks of neocartilage formation. Varying the duration of aggregate redifferentiation generated a spectrum of fibrous to hyaline neocartilage. Within 8 days of aggregation, proliferation ceased, and collagen and glycosaminoglycan production increased, compared with monolayer cells. In self-assembled neocartilage, type II-to-I collagen ratio increased with increasing aggregate duration, yet glycosaminoglycan content varied minimally. Notably, 14 days of aggregate redifferentiation increased collagen content by 25%, tensile modulus by over 110%, and compressive moduli by over 50%, compared with tissue formed in the absence of redifferentiation. A spectrum of fibrous to hyaline cartilage was generated using a single, clinically relevant cell source, improving the translational potential of engineered cartilage.
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Affiliation(s)
- Meghan K Murphy
- Department of Biomedical Engineering, University of California Davis, Davis, CA, USA
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122
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Mohanraj B, Farran AJ, Mauck RL, Dodge GR. Time-dependent functional maturation of scaffold-free cartilage tissue analogs. J Biomech 2013; 47:2137-42. [PMID: 24262848 DOI: 10.1016/j.jbiomech.2013.10.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 10/12/2013] [Indexed: 01/28/2023]
Abstract
One of the most critical parameters in cartilage tissue engineering which influences the clinical success of a repair therapy is the ability to match the load-bearing capacity of the tissue as it functions in vivo. While mechanical forces are known to positively influence the development of cartilage matrix architecture, these same forces can induce long-term implant failure due to poor integration or structural deficiencies. As such, in the design of optimal repair strategies, it is critical to understand the timeline of construct maturation and how the elaboration of matrix correlates with the development of mechanical properties. We have previously characterized a scaffold-free method to engineer cartilage utilizing primary chondrocytes cultured at high density in hydrogel-coated culture vessels to promote the formation of a self-aggregating cell suspension that condenses to form a cartilage-like biomass, or cartilage tissue analog (CTA). Chondrocytes in these CTAs maintain their cellular phenotype and deposit extracellular matrix to form a construct that has characteristics similar to native cartilage; however, the mechanical integrity of CTAs had not yet been evaluated. In this study, we found that chondrocytes within CTAs produced a robust matrix of proteoglycans and collagen that correlated with increasing mechanical properties and decreasing cell-matrix ratios, leading to properties that approached that of native cartilage. These results demonstrate a unique approach to generating a cartilage-like tissue without the complicating factor of scaffold, while showing increased compressive properties and matrix characteristics consistent with other approaches, including scaffold-based constructs. To further improve the mechanics of CTAs, studies are currently underway to explore the effect of hydrodynamic loading and whether these changes would be reflective of in vivo maturation in animal models. The functional maturation of cartilage tissue analogs as described here support this engineered cartilage model for use in clinical and experimental applications for repair and regeneration in joint-related pathologies.
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Affiliation(s)
- Bhavana Mohanraj
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, 36th Street and Hamilton Walk, Philadelphia, PA 19104, USA; Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Alexandra J Farran
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, 36th Street and Hamilton Walk, Philadelphia, PA 19104, USA
| | - Robert L Mauck
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, 36th Street and Hamilton Walk, Philadelphia, PA 19104, USA; Collaborative Research Partner Acute Cartilage Injury Program of AO Foundation, Davos, Switzerland; Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - George R Dodge
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, 36th Street and Hamilton Walk, Philadelphia, PA 19104, USA; Collaborative Research Partner Acute Cartilage Injury Program of AO Foundation, Davos, Switzerland.
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123
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Tian HT, Zhang B, Tian Q, Liu Y, Yang SH, Shao ZW. Construction of self-assembled cartilage tissue from bone marrow mesenchymal stem cells induced by hypoxia combined with GDF-5. ACTA ACUST UNITED AC 2013; 33:700-706. [PMID: 24142723 DOI: 10.1007/s11596-013-1183-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Revised: 09/04/2013] [Indexed: 01/08/2023]
Abstract
It is widely known that hypoxia can promote chondrogenesis of human bone marrow derived mesenchymal stem cells (hMSCs) in monolayer cultures. However, the direct impact of oxygen tension on hMSC differentiation in three-dimensional cultures is still unknown. This research was designed to observe the direct impact of oxygen tension on the ability of hMSCs to "self assemble" into tissue-engineered cartilage constructs. hMSCs were cultured in chondrogenic medium (CM) containing 100 ng/mL growth differentiation factor 5 (GDF-5) at 5% (hypoxia) and 21% (normoxia) O2 levels in monolayer cultures for 3 weeks. After differentiation, the cells were digested and employed in a self-assembly process to produce tissue-engineered constructs under hypoxic and normoxic conditions in vitro. The aggrecan and type II collagen expression, and type X collagen in the self-assembled constructs were assessed by using immunofluorescent and immunochemical staining respectively. The methods of dimethylmethylene blue (DMMB), hydroxyproline and PicoGreen were used to measure the total collagen content, glycosaminoglycan (GAG) content and the number of viable cells in each construct, respectively. The expression of type II collagen and aggrecan under hypoxic conditions was increased significantly as compared with that under normoxic conditions. In contrast, type X collagen expression was down-regulated in the hypoxic group. Moreover, the constructs in hypoxic group showed more significantly increased total collagen and GAG than in normoxic group, which were more close to those of the natural cartilage. These findings demonstrated that hypoxia enhanced chondrogenesis of in vitro, scaffold-free, tissue-engineered constructs generated using hMSCs induced by GDF-5. In hypoxic environments, the self-assembled constructs have a Thistological appearance and biochemical parameters similar to those of the natural cartilage.
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Affiliation(s)
- Hong-Tao Tian
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Bo Zhang
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Qing Tian
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Yong Liu
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
| | - Shu-Hua Yang
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Zeng-Wu Shao
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
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124
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Higashioka MM, Chen JA, Hu JC, Athanasiou KA. Building an anisotropic meniscus with zonal variations. Tissue Eng Part A 2013; 20:294-302. [PMID: 23931258 DOI: 10.1089/ten.tea.2013.0098] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Toward addressing the difficult problems of knee meniscus regeneration, a self-assembling process has been used to re-create the native morphology and matrix properties. A significant problem in such attempts is the recapitulation of the distinct zones of the meniscus, the inner, more cartilaginous and the outer, more fibrocartilaginous zones. In this study, an anisotropic and zonally variant meniscus was produced by self-assembly of the inner meniscus (100% chondrocytes) followed by cell seeding the outer meniscus (coculture of chondrocytes and meniscus cells). After 4 weeks in culture, the engineered, inner meniscus exhibited a 42% increase in both instantaneous and relaxation moduli and a 62% increase in GAG/DW, as compared to the outer meniscus. In contrast, the circumferential tensile modulus and collagen/DW of the outer zone was 101% and 129% higher, respectively, than the values measured for the inner zone. Furthermore, there was no difference in the radial tensile modulus between the control and zonal engineered menisci, suggesting that the inner and outer zones of the engineered zonal menisci successfully integrated. These data demonstrate that not only can biomechanical and biochemical properties be engineered to differ by the zone, but they can also recapitulate the anisotropic behavior of the knee meniscus.
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Affiliation(s)
- Michael M Higashioka
- 1 Department of Biomedical Engineering, University of California Davis , Davis, California
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125
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MacBarb RF, Chen AL, Hu JC, Athanasiou KA. Engineering functional anisotropy in fibrocartilage neotissues. Biomaterials 2013; 34:9980-9. [PMID: 24075479 DOI: 10.1016/j.biomaterials.2013.09.026] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Accepted: 09/06/2013] [Indexed: 11/26/2022]
Abstract
The knee meniscus, intervertebral disc, and temporomandibular joint (TMJ) disc all possess complex geometric shapes and anisotropic matrix organization. While these characteristics are imperative for proper tissue function, they are seldom recapitulated following injury or disease. Thus, this study's objective was to engineer fibrocartilages that capture both gross and molecular structural features of native tissues. Self-assembled TMJ discs were selected as the model system, as the disc exhibits a unique biconcave shape and functional anisotropy. To drive anisotropy, 50:50 co-cultures of meniscus cells and articular chondrocytes were grown in biconcave, TMJ-shaped molds and treated with two exogenous stimuli: biomechanical (BM) stimulation via passive axial compression and bioactive agent (BA) stimulation via chondroitinase-ABC and transforming growth factor-β1. BM + BA synergistically increased Col/WW, Young's modulus, and ultimate tensile strength 5.8-fold, 14.7-fold, and 13.8-fold that of controls, respectively; it also promoted collagen fibril alignment akin to native tissue. Finite element analysis found BM stimulation to create direction-dependent strains within the neotissue, suggesting shape plays an essential role toward driving in vitro anisotropic neotissue development. Methods used in this study offer insight on the ability to achieve physiologic anisotropy in biomaterials through the strategic application of spatial, biomechanical, and biochemical cues.
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Affiliation(s)
- Regina F MacBarb
- Department of Biomedical Engineering, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
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126
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Kock LM, Ito K, van Donkelaar CC. Sliding Indentation Enhances Collagen Content and Depth-Dependent Matrix Distribution in Tissue-Engineered Cartilage Constructs. Tissue Eng Part A 2013; 19:1949-59. [DOI: 10.1089/ten.tea.2012.0688] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Linda M. Kock
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Keita Ito
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Corrinus C. van Donkelaar
- Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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127
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Mesallati T, Buckley CT, Kelly DJ. A comparison of self-assembly and hydrogel encapsulation as a means to engineer functional cartilaginous grafts using culture expanded chondrocytes. Tissue Eng Part C Methods 2013; 20:52-63. [PMID: 23672760 DOI: 10.1089/ten.tec.2013.0118] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Despite an increased interest in the use of hydrogel encapsulation and cellular self-assembly (often termed "self-aggregating" or "scaffold-free" approaches) for tissue-engineering applications, to the best of our knowledge, no study to date has been undertaken to directly compare both approaches for generating functional cartilaginous grafts. The objective of this study was to directly compare self-assembly (SA) and agarose hydrogel encapsulation (AE) as a means to engineer such grafts using passaged chondrocytes. Agarose hydrogels (5 mm diameter × 1.5 mm thick) were seeded with chondrocytes at two cell seeding densities (900,000 cells or 4 million cells in total per hydrogel), while SA constructs were generated by adding the same number of cells to custom-made molds. Constructs were either supplemented with transforming growth factor (TGF)-β3 for 6 weeks, or only supplemented with TGF-β3 for the first 2 weeks of the 6 week culture period. The SA method was only capable of generating geometrically uniform cartilaginous tissues at high seeding densities (4 million cells). At these high seeding densities, we observed that total sulphated glycosaminoglycan (sGAG) and collagen synthesis was greater with AE than SA, with higher sGAG retention also observed in AE constructs. When normalized to wet weight, however, SA constructs exhibited significantly higher levels of collagen accumulation compared with agarose hydrogels. Furthermore, it was possible to engineer such functionality into these tissues in a shorter timeframe using the SA approach compared with AE. Therefore, while large numbers of chondrocytes are required to engineer cartilaginous grafts using the SA approach, it would appear to lead to the faster generation of a more hyaline-like tissue, with a tissue architecture and a ratio of collagen to sGAG content more closely resembling native articular cartilage.
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Affiliation(s)
- Tariq Mesallati
- 1 Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin , Dublin, Ireland
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128
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Ahtiainen K, Mauno J, Ellä V, Hagström J, Lindqvist C, Miettinen S, Ylikomi T, Kellomäki M, Seppänen R. Autologous adipose stem cells and polylactide discs in the replacement of the rabbit temporomandibular joint disc. J R Soc Interface 2013; 10:20130287. [PMID: 23720535 DOI: 10.1098/rsif.2013.0287] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The temporomandibular joint (TMJ) disc lacks functional replacement after discectomy. We investigated tissue-engineered bilayer polylactide (PLA) discs and autologous adipose stem cells (ASCs) as a potential replacement for the TMJ disc. These ASC discs were pre-cultured either in control or in differentiation medium, including transforming growth factor (TGF)-β1 for one week. Prior to implantation, expression of fibrocartilaginous genes was measured by qRT-PCR. The control and differentiated ASC discs were implanted, respectively, in the right and left TMJs of rabbits for six (n = 5) and 12 months (n = 5). Thereafter, the excised TMJ areas were examined with cone beam computed tomography (CBCT) and histology. No signs of infection, inflammation or foreign body reactions were detected at histology, whereas chronic arthrosis and considerable condylar hypertrophy were observed in all operated joints at CBCT. The left condyle treated with the differentiated ASC discs appeared consistently smoother and more sclerotic than the right condyle. The ASC disc replacement resulted in dislocation and morphological changes in the rabbit TMJ. The ASC discs pre-treated with TGF-β1 enhanced the condylar integrity. While adverse tissue reactions were not shown, the authors suggest that with improved attachment and design, the PLA disc and biomaterial itself would hold potential for TMJ disc replacement.
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Affiliation(s)
- Katja Ahtiainen
- Department of Cell Biology, School of Medicine, University of Tampere, 33014 Tampere, Finland
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129
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Athanasiou KA, Eswaramoorthy R, Hadidi P, Hu JC. Self-organization and the self-assembling process in tissue engineering. Annu Rev Biomed Eng 2013; 15:115-36. [PMID: 23701238 DOI: 10.1146/annurev-bioeng-071812-152423] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In recent years, the tissue engineering paradigm has shifted to include a new and growing subfield of scaffoldless techniques that generate self-organizing and self-assembling tissues. This review aims to cogently describe this relatively new research area, with special focus on applications toward clinical use and research models. Particular emphasis is placed on providing clear definitions of self-organization and the self-assembling process, as delineated from other scaffoldless techniques in tissue engineering and regenerative medicine. Significantly, during formation, self-organizing and self-assembling tissues display biological processes similar to those that occur in vivo. These processes help lead to the recapitulation of native tissue morphological structure and organization. Notably, functional properties of these engineered tissues, some of which are already in clinical trials, also approach native tissue values. This review endeavors to provide a cohesive summary of work in this field and to highlight the potential of self-organization and the self-assembling process for providing cogent solutions to currently intractable problems in tissue engineering.
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Affiliation(s)
- Kyriacos A Athanasiou
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA.
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130
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Athens AA, Makris EA, Hu JC. Induced collagen cross-links enhance cartilage integration. PLoS One 2013; 8:e60719. [PMID: 23593295 PMCID: PMC3617163 DOI: 10.1371/journal.pone.0060719] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 03/01/2013] [Indexed: 11/19/2022] Open
Abstract
Articular cartilage does not integrate due primarily to a scarcity of cross-links and viable cells at the interface. The objective of this study was to test the hypothesis that lysyl-oxidase, a metalloenzyme that forms collagen cross-links, would be effective in improving integration between native-to-native, as well as tissue engineered-to-native cartilage surfaces. To examine these hypotheses, engineered cartilage constructs, synthesized via the self-assembling process, as well as native cartilage, were implanted into native cartilage rings and treated with lysyl-oxidase for varying amounts of time. For both groups, lysyl-oxidase application resulted in greater apparent stiffness across the cartilage interface 2–2.2 times greater than control. The construct-to-native lysyl-oxidase group also exhibited a statistically significant increase in the apparent strength, here defined as the highest observed peak stress during tensile testing. Histology indicated a narrowing gap at the cartilage interface in lysyl-oxidase treated groups, though this alone is not sufficient to indicate annealing. However, when the morphological and mechanical data are taken together, the longer the duration of lysyl-oxidase treatment, the more integrated the interface appeared. Though further data are needed to confirm the mechanism of action, the enhancement of integration may be due to lysyl-oxidase-induced pyridinoline cross-links. This study demonstrates that lysyl-oxidase is a potent agent for enhancing integration between both native-to-native and native-to-engineered cartilages. The fact that interfacial strength increased manifold suggests that cross-linking agents should play a significant role in solving the difficult problem of cartilage integration. Future studies must examine dose, dosing regimen, and cellular responses to lysyl-oxidase to optimize its application.
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Affiliation(s)
- Aristos A. Athens
- Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America
- Davis Senior High School, Davis, California, United States of America
| | - Eleftherios A. Makris
- Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America
- Department of Orthopedic Surgery and Musculoskeletal Trauma, University of Thessaly (BIOMED), Larisa, Greece
| | - Jerry C. Hu
- Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America
- * E-mail:
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131
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Makris E, Hu J, Athanasiou K. Hypoxia-induced collagen crosslinking as a mechanism for enhancing mechanical properties of engineered articular cartilage. Osteoarthritis Cartilage 2013; 21:634-41. [PMID: 23353112 PMCID: PMC3670708 DOI: 10.1016/j.joca.2013.01.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 01/05/2013] [Accepted: 01/15/2013] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The focus of tissue engineering of neocartilage has traditionally been on enhancing extracellular matrix and thus biomechanical properties. Emphasis has been placed on the enhancement of collagen type and quantity, and, concomitantly, tensile properties. The objective of this study was to improve crosslinking of the collagen network by testing the hypothesis that hypoxia could promote pyridinoline (PYR) crosslinks and, thus, improve neocartilage's tensile properties. METHODS Chondrocyte expression of lysyl oxidase (LOX), an enzyme responsible for the formation of collagen PYR crosslinks, was first assessed pre- and post- hypoxia application. Then, the mechanical properties of self-assembled neocartilage constructs were measured, after 4 weeks of culture, for groups exposed to 4% O2 at different initiation times and durations, i.e., during the 1st and 3rd weeks, 3rd and 4th weeks, 4th week only, continuously after cell seeding, or never. RESULTS Results showed that LOX gene expression was upregulated ∼20-fold in chondrocytes in response to hypoxia. Hypoxia applied during the 3rd and 4th weeks significantly increased PYR crosslinks without affecting collagen content. Excitingly, neocartilage tensile properties were increased ∼2-fold. It should be noted that these properties exhibited a distinct temporal dependence to hypoxia exposure, since upregulation of these properties was due to hypoxia applied only during the 3rd and 4th weeks. CONCLUSION These data elucidate the role of hypoxia-mediated upregulation of LOX and subsequent increases in PYR crosslinks in engineered cartilage. These results hold promise toward applying hypoxia at precise time points to promote tensile integrity and direct construct maturation.
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Affiliation(s)
- E.A. Makris
- Department of Biomedical Engineering, University of California Davis, One Shields Avenue, Davis, CA 95616, USA,Department of Orthopedic Surgery and Musculoskeletal Trauma, University of Thessaly (BIOMED), Larisa 41110, Greece
| | - J.C. Hu
- Department of Biomedical Engineering, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - K.A. Athanasiou
- Department of Biomedical Engineering, University of California Davis, One Shields Avenue, Davis, CA 95616, USA,Address correspondence and reprint requests to: K.A. Athanasiou, Department of Biomedical Engineering, University of California Davis, One Shields Avenue, Davis, CA 95616, USA. Tel: 1-530-754-6645; Fax: 1-530-754-5739
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132
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Hoenig E, Leicht U, Winkler T, Mielke G, Beck K, Peters F, Schilling AF, Morlock MM. Mechanical properties of native and tissue-engineered cartilage depend on carrier permeability: a bioreactor study. Tissue Eng Part A 2013; 19:1534-42. [PMID: 23387321 DOI: 10.1089/ten.tea.2012.0538] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The implantation of osteochondral constructs-tissue-engineered (TE) cartilage on a bone substitute carrier-is a promising method to treat defects in articular cartilage. Currently, however, the TE cartilage's mechanical properties are clearly inferior to those of native cartilage. Their improvement has been the subject of various studies, mainly focusing on growth factors and physical loading during cultivation. With the approach of osteochondral constructs another aspect arises: the permeability of the carrier materials. The purpose of this study was to investigate whether and how the permeability of the subchondral bone influences the properties of native cartilage and whether the bone substitute carrier's permeability influences the TE cartilage of osteochondral constructs accordingly. Consequently, the influence of the subchondral bone's permeability on native cartilage was determined: Native porcine cartilage-bone cylinders were cultivated for 2 weeks in a bioreactor under mechanical loading with and without restricted permeability of the bone. For the TE cartilage these two permeability conditions were investigated using permeable and impermeable tricalciumphosphate carriers under equivalent cultivation conditions. All specimens were evaluated mechanically, biochemically, and histologically. The restriction of the bone's permeability significantly decreased the Young's modulus of native cartilage in vitro. No biochemical differences were found. This finding was confirmed for TE cartilage: While the biochemical parameters were not affected, a permeable carrier improved the cell morphology and mechanical properties in comparison to an impermeable one. In conclusion, the carrier permeability was identified as a determining factor for the mechanical properties of TE cartilage of osteochondral constructs.
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Affiliation(s)
- Elisa Hoenig
- Biomechanics Section, Hamburg University of Technology, Hamburg, Germany.
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133
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Makris EA, MacBarb RF, Responte DJ, Hu JC, Athanasiou KA. A copper sulfate and hydroxylysine treatment regimen for enhancing collagen cross-linking and biomechanical properties in engineered neocartilage. FASEB J 2013; 27:2421-30. [PMID: 23457219 DOI: 10.1096/fj.12-224030] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The objective of this study was to improve the biomechanical properties of engineered neotissues through promoting the development of collagen cross-links. It was hypothesized that supplementing medium with copper sulfate and the amino acid hydroxylysine would enhance the activity of lysyl oxidase enzyme to form collagen cross-links, increasing the strength and integrity of the neotissue. Neocartilage constructs were generated using a scaffoldless, self-assembling process and treated with copper sulfate and hydroxylysine, either alone or in combination, following a 2-factor, full-factorial study design. Following a 6-wk culture period, the biomechanical and biochemical properties of the constructs were measured. Results found copper sulfate to significantly increase pyridinoline (PYR) cross-links in all copper sulfate-containing groups over controls. When copper sulfate and hydroxylysine were combined, the result was synergistic, with a 10-fold increase in PYR content over controls. This increase in PYR cross-links manifested in a 3.3-fold significant increase in the tensile properties of the copper sulfate + hydroxylysine group. In addition, an 123% increase over control values was detected in the copper sulfate group in terms of the aggregate modulus. These data elucidate the role of copper sulfate and hydroxylysine toward improving the biomechanical properties of neotissues through collagen cross-linking enhancement.
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Affiliation(s)
- Eleftherios A Makris
- Department of Biomedical Engineering, University of California-Davis, Davis, CA 95616, USA
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134
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Eleswarapu SV, Athanasiou KA. TRPV4 channel activation improves the tensile properties of self-assembled articular cartilage constructs. Acta Biomater 2013; 9:5554-61. [PMID: 23128162 DOI: 10.1016/j.actbio.2012.10.031] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 10/19/2012] [Accepted: 10/26/2012] [Indexed: 11/18/2022]
Abstract
A persistent hurdle in the field of tissue regeneration is to produce tissues with biochemical and biomechanical properties robust enough to meet the aggressive physiological demands of the native milieu. In an effort to improve these properties tissues grown in vitro are often subjected to mechanical stimuli that aim to recapitulate the in vivo physiology. These mechanical stimuli are thought to produce downstream alterations in intracellular ion concentrations, which ultimately give rise to increased biosynthesis. There is mounting evidence that these perturbations in the cellular microenvironment are regulated by the Ca(2+)-permeable transient receptor potential vanilloid 4 (TRPV4) channel. In this study we examined the effects of targeted TRPV4 activation on self-assembled articular cartilage constructs. The objectives of this study were: (i) to determine whether TRPV4 activation would enhance self-assembled constructs; (ii) to identify an optimal treatment time window for TRPV4 activation; and (iii) to compare TRPV4 activation which Na(+)/K(+) pump inhibition, which has previously been shown to improve the construct tensile properties. This study employed a two phase approach. In Phase I self-assembled constructs were grown for 4weeks and subjected to treatment with the TRPV4 agonist 4α-phorbol-12,13-didecanoate (4α-PDD) during three treatment time windows: t=6-10, t=10-14, and t=14-18days. Treatment for t=10-14days produced an 88% increase in collagen and a 153% increase in tensile stiffness. This treatment window was carried forward to Phase II. In Phase II we performed a head to head comparison between TRPV4 activation using 4α-PDD and Na(+)/K(+) pump inhibition using ouabain. Treatment with 4α-PDD produced improvements on a par with ouabain (91-107% increases in tensile stiffness). The results of this study demonstrate the effectiveness of ion channel modulation as a strategy for improving engineered tissues. To our knowledge this is the first study to examine TRPV4 channel activation in tissue engineering.
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Affiliation(s)
- Sriram V Eleswarapu
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
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135
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Hadidi P, Athanasiou KA. Enhancing the mechanical properties of engineered tissue through matrix remodeling via the signaling phospholipid lysophosphatidic acid. Biochem Biophys Res Commun 2013; 433:133-8. [PMID: 23458458 DOI: 10.1016/j.bbrc.2013.02.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 02/10/2013] [Indexed: 02/07/2023]
Abstract
Knee meniscus fibrocartilage is frequently injured, resulting in approximately 1 million procedures annually in the US and Europe. Its near-avascularity contributes heavily to its inability to heal, and places it as a prime candidate for replacement through regenerative medicine. Here, we describe a novel approach to increase extracellular matrix organization, rather than content, in order to augment the mechanical properties of engineered tissue. To synthesize fibrocartilage, we employ a self-assembling process, which is free of exogenous scaffolds and relies on cell-to-cell interactions to form all-biologic constructs. When treated with the signaling phospholipid lysophosphatidic acid (LPA), tissue constructs displayed increased tensile properties and collagen organization, while total collagen content remained unchanged. LPA-treated constructs exhibited greater DNA content, indicative that the molecule exerted a signaling effect. Furthermore, LPA-treated cells displayed significant cytoskeletal reorganization. We conclude that LPA induced cytoskeletal reorganization and cell-matrix traction, which resulted in matrix reorganization and increased tensile properties. This study emphasizes the potential of non-traditional stimuli, such as signaling phospholipids, for use in tissue development studies. The extension of these results to other collagen-rich tissues represents a promising avenue for future exploration.
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Affiliation(s)
- Pasha Hadidi
- Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
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136
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Murphy MK, Huey DJ, Reimer AJ, Hu JC, Athanasiou KA. Enhancing post-expansion chondrogenic potential of costochondral cells in self-assembled neocartilage. PLoS One 2013; 8:e56983. [PMID: 23437288 PMCID: PMC3578801 DOI: 10.1371/journal.pone.0056983] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 01/16/2013] [Indexed: 11/18/2022] Open
Abstract
The insufficient healing capacity of articular cartilage necessitates mechanically functional biologic tissue replacements. Using cells to form biomimetic cartilage implants is met with the challenges of cell scarcity and donor site morbidity, requiring expanded cells that possess the ability to generate robust neocartilage. To address this, this study assesses the effects of expansion medium supplementation (bFGF, TFP, FBS) and self-assembled construct seeding density (2, 3, 4 million cells/5 mm dia. construct) on the ability of costochondral cells to generate biochemically and biomechanically robust neocartilage. Results show TFP (1 ng/mL TGF-β1, 5 ng/mL bFGF, 10 ng/mL PDGF) supplementation of serum-free chondrogenic expansion medium enhances the post-expansion chondrogenic potential of costochondral cells, evidenced by increased glycosaminoglycan content, decreased type I/II collagen ratio, and enhanced compressive properties. Low density (2 million cells/construct) enhances matrix synthesis and tensile and compressive mechanical properties. Combined, TFP and Low density interact to further enhance construct properties. That is, with TFP, Low density increases type II collagen content by over 100%, tensile stiffness by over 300%, and compressive moduli by over 140%, compared with High density. In conclusion, the interaction of TFP and Low density seeding enhances construct material properties, allowing for a mechanically functional, biomimetic cartilage to be formed using clinically relevant costochondral cells.
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Affiliation(s)
- Meghan K. Murphy
- Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America
| | - Daniel J. Huey
- Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America
| | - Andrew J. Reimer
- Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America
| | - Jerry C. Hu
- Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America
| | - Kyriacos A. Athanasiou
- Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America
- * E-mail:
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137
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Huey DJ, Athanasiou KA. Alteration of the fibrocartilaginous nature of scaffoldless constructs formed from leporine meniscus cells and chondrocytes through manipulation of culture and processing conditions. Cells Tissues Organs 2013; 197:360-71. [PMID: 23406714 DOI: 10.1159/000346252] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/03/2012] [Indexed: 11/19/2022] Open
Abstract
Articular cartilage and the menisci of the knee joint lack intrinsic repair capacity; thus, injuries to these tissues result in eventual osteoarthrotic changes to the joint. Tissue engineering offers the potential to replace damaged cartilage and mitigate long-term debilitating changes to the joint. In an attempt to enhance the ability of adult articular chondrocytes (ACs) and meniscus cells (MCs) to produce robust scaffoldless neocartilage, the effects of passage number, cryopreservation, and redifferentiation prior to construct formation were studied. By increasing passage number, smaller donor biopsies could be used to generate sufficient cells for tissue engineering and, in this study, no detrimental effects were observed when employing passage-4 versus passage-3 cells. Cryopreservation of cells would enable the generation of a cell bank thus reducing lead time and enhancing consistency of cell-based therapies. Interestingly, cryopreservation was shown to enhance the biomechanical properties of the resultant self-assembled constructs. With regard to redifferentiation prior to construct formation, aggregate redifferentiation was shown to enhance the biochemical and biomechanical properties of self-assembled constructs. By increasing passaging number, cryopreserving cells, and applying aggregate redifferentiation prior to neotissue formation, the utility of ACs and MCs in tissue engineering can be enhanced.
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Affiliation(s)
- Daniel J Huey
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
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138
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MacBarb RF, Makris EA, Hu JC, Athanasiou KA. A chondroitinase-ABC and TGF-β1 treatment regimen for enhancing the mechanical properties of tissue-engineered fibrocartilage. Acta Biomater 2013; 9:4626-34. [PMID: 23041782 DOI: 10.1016/j.actbio.2012.09.037] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 08/24/2012] [Accepted: 09/27/2012] [Indexed: 10/27/2022]
Abstract
The development of functionally equivalent fibrocartilage remains elusive despite efforts to engineer tissues such as knee meniscus, intervertebral disc and temporomandibular joint disc. Attempts to engineer these structures often fail to create tissues with mechanical properties on a par with native tissue, resulting in constructs unsuitable for clinical applications. The objective of this study was to engineer a spectrum of biomimetic fibrocartilages representative of the distinct functional properties found in native tissues. Using the self-assembly process, different co-cultures of meniscus cells and articular chondrocytes were seeded into agarose wells and treated with the catabolic agent chondroitinase-ABC (C-ABC) and the anabolic agent transforming growth factor-β1 (TGF-β1) via a two-factor (cell ratio and bioactive treatment), full factorial study design. Application of both C-ABC and TGF-β1 resulted in a beneficial or positive increase in the collagen content of treated constructs compared to controls. Significant increases in both the collagen density and fiber diameter were also seen with this treatment, increasing these values by 32 and 15%, respectively, over control values. Mechanical testing found the combined bioactive treatment to synergistically increase the Young's modulus and ultimate tensile strength of the engineered fibrocartilages compared to controls, with values reaching the lower spectrum of those found in native tissues. Together, these data demonstrate that C-ABC and TGF-β1 interact to develop a denser collagen matrix better able to withstand tensile loading. This study highlights a way to optimize the tensile properties of engineered fibrocartilage using a biochemical and a biophysical agent together to create distinct fibrocartilages with functional properties mimicking those of native tissue.
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139
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DuRaine GD, Athanasiou KA. ERK activation is required for hydrostatic pressure-induced tensile changes in engineered articular cartilage. J Tissue Eng Regen Med 2012; 9:368-74. [PMID: 23255524 DOI: 10.1002/term.1678] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 07/23/2012] [Accepted: 11/10/2012] [Indexed: 02/06/2023]
Abstract
The objective of this study was to identify ERK 1/2 involvement in the changes in compressive and tensile mechanical properties associated with hydrostatic pressure treatment of self-assembled cartilage constructs. In study 1, ERK 1/2 phosphorylation was detected by immunoblot, following application of hydrostatic pressure (1 h of static 10 MPa) applied at days 10-14 of self-assembly culture. In study 2, ERK 1/2 activation was blocked during hydrostatic pressure application on days 10-14. With pharmacological inhibition of the ERK pathway by the MEK1/ERK inhibitor U0126 during hydrostatic pressure application on days 10-14, the increase in Young's modulus induced by hydrostatic pressure was blocked. Furthermore, this reduction in Young's modulus with U0126 treatment during hydrostatic pressure application corresponded to a decrease in total collagen expression. However, U0126 did not inhibit the increase in aggregate modulus or GAG induced by hydrostatic pressure. These findings demonstrate a link between hydrostatic pressure application, ERK signalling and changes in the biomechanical properties of a tissue-engineered construct.
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Affiliation(s)
- G D DuRaine
- Department of Biomedical Engineering, University of California, Davis, CA, USA
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140
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Izadifar Z, Chen X, Kulyk W. Strategic design and fabrication of engineered scaffolds for articular cartilage repair. J Funct Biomater 2012; 3:799-838. [PMID: 24955748 PMCID: PMC4030923 DOI: 10.3390/jfb3040799] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 09/13/2012] [Accepted: 10/17/2012] [Indexed: 01/19/2023] Open
Abstract
Damage to articular cartilage can eventually lead to osteoarthritis (OA), a debilitating, degenerative joint disease that affects millions of people around the world. The limited natural healing ability of cartilage and the limitations of currently available therapies make treatment of cartilage defects a challenging clinical issue. Hopes have been raised for the repair of articular cartilage with the help of supportive structures, called scaffolds, created through tissue engineering (TE). Over the past two decades, different designs and fabrication techniques have been investigated for developing TE scaffolds suitable for the construction of transplantable artificial cartilage tissue substitutes. Advances in fabrication technologies now enable the strategic design of scaffolds with complex, biomimetic structures and properties. In particular, scaffolds with hybrid and/or biomimetic zonal designs have recently been developed for cartilage tissue engineering applications. This paper reviews critical aspects of the design of engineered scaffolds for articular cartilage repair as well as the available advanced fabrication techniques. In addition, recent studies on the design of hybrid and zonal scaffolds for use in cartilage tissue repair are highlighted.
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Affiliation(s)
- Zohreh Izadifar
- Division of Biomedical Engineering, College of Engineering, University of Saskatchewan, 57 Campus Dr., Saskatoon SK S7N5A9, Canada.
| | - Xiongbiao Chen
- Division of Biomedical Engineering, College of Engineering, University of Saskatchewan, 57 Campus Dr., Saskatoon SK S7N5A9, Canada.
| | - William Kulyk
- Department of Anatomy and Cell Biology, College of Medicine, University of Saskatchewan, 107 Wiggins Rd., Saskatoon SK S7N 5E5, Canada.
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141
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Sun Z, Zhang Y, Yang S, Jia J, Ye S, Chen D, Mo F. Growth differentiation factor 5 modulation of chondrogenesis of self-assembled constructs involves gap junction-mediated intercellular communication. Dev Growth Differ 2012; 54:809-17. [PMID: 23121099 DOI: 10.1111/dgd.12009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 09/03/2012] [Accepted: 09/14/2012] [Indexed: 11/28/2022]
Abstract
A novel scaffold-free self-assembled cartilage construct has been generated and used to repair particular chondral defects effectively. However, the mechanisms related to the construction of these self-assembled cartilages have not yet been fully elucidated. We hypothesize that gap junction intercellular communication (GJIC) plays a critical role in the development of self-assembled constructs upon GDF-5 induction. In this study, we investigated the effect of connexin 43 (C×43) mediated GJIC on GDF-5 modulation of chondrogenesis from two aspects, cell monolayer culture and 3-D self-assembly culture. We induced cells or self-assembled constructs with chondrogenic media (CM), growth differentiation factor 5 (GDF-5) or 1-heptanol for 3 weeks. At the end of that time, the results of quantitative fluorescence redistribution after photobleaching (FRAP) assay and immunofluorescence demonstrated that GDF-5 improved both GJIC and chondrogenic differentiation to a significant degree while 1-heptanol nearly offset the expected improvements in chondrogenesis. Biochemical assay and histology showed that GDF-5 can obviously enhance GAG, C×43 and type II collagen expressions. Conversely, we also showed that while 1-heptanol weakened GAG and type II collagen expression in self-assembled constructs, it had no effect on C×43 expression. Furthermore, real-time polymerase chain reaction showed that GDF-5 enhanced GAG and type II collagen transcription while 1-heptanol reduced them, but was affectless on C×43 transcription. This suggests that the generation of scaffold-free self-assembled cartilage from human mesenchymal stem cells upon GDF-5 induction may be mediated, at least in part, via the modulation of GJIC.
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Affiliation(s)
- Zhibo Sun
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, Hubei, China
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142
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Huey DJ, Hu JC, Athanasiou KA. Chondrogenically tuned expansion enhances the cartilaginous matrix-forming capabilities of primary, adult, leporine chondrocytes. Cell Transplant 2012; 22:331-40. [PMID: 23044188 DOI: 10.3727/096368912x657648] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
When expanded through passage, chondrocytes lose their ability to produce high-quality cartilaginous matrix. This study attempts to improve the properties of constructs formed with expanded chondrocytes through alterations in the expansion protocol and the ratio of primary to expanded chondrocytes used to form cartilage constructs. A chondrogenically tuned expansion protocol provided similar monolayer growth rates as those obtained using serum-containing medium and enhanced cartilaginous properties of resultant constructs. Various ratios of primary to chondrogenically expanded chondrocytes were then self-assembled to form neocartilage. Biochemical analysis showed that constructs formed with only expanded cells had twice the GAG per wet weight and collagen II/collagen I ratio compared to constructs formed with primary chondrocytes. Biomechanically, compressive properties of constructs formed with only passaged cells matched the instantaneous modulus and exceeded the relaxation modulus of constructs formed with only primary cells. These counterintuitive results show that, by applying proper expansion and three-dimensional culture techniques, the cartilage-forming potential of adult chondrocytes expanded through passage can be enhanced over that of primary cells.
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Affiliation(s)
- Daniel J Huey
- Department of Biomedical Engineering, University of California-Davis, Davis, CA 95616, USA
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143
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Responte DJ, Natoli RM, Athanasiou KA. Identification of potential biophysical and molecular signalling mechanisms underlying hyaluronic acid enhancement of cartilage formation. J R Soc Interface 2012; 9:3564-73. [PMID: 22809846 DOI: 10.1098/rsif.2012.0399] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This study determined the effects of exogenous hyaluronic acid (HA) on the biomechanical and biochemical properties of self-assembled bovine chondrocytes, and investigated biophysical and genetic mechanisms underlying these effects. The effects of HA commencement time, concentration, application duration and molecular weight were examined using histology, biomechanics and biochemistry. Additionally, the effects of HA application on sulphated glycosaminoglycan (GAG) retention were assessed. To investigate the influence of HA on gene expression, microarray analysis was conducted. HA treatment of developing neocartilage increased compressive stiffness onefold and increased sulphated GAG content by 35 per cent. These effects were dependent on HA molecular weight, concentration and application commencement time. Additionally, applying HA increased sulphated GAG retention within self-assembled neotissue. HA administration also upregulated 503 genes, including multiple genes associated with TGF-β1 signalling. Increased sulphated GAG retention indicated that HA could enhance compressive stiffness by increasing the osmotic pressure that negatively charged GAGs create. The gene expression data demonstrate that HA treatment differentially regulates genes related to TGF-β1 signalling, revealing a potential mechanism for altering matrix composition. These results illustrate the potential use of HA to improve cartilage regeneration efforts and better understand cartilage development.
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Affiliation(s)
- Donald J Responte
- Department of Bioengineering, Rice University, , 6500 Main St., Suite 135, Houston, TX 77030, USA
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144
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Achilli TM, Meyer J, Morgan JR. Advances in the formation, use and understanding of multi-cellular spheroids. Expert Opin Biol Ther 2012; 12:1347-60. [PMID: 22784238 DOI: 10.1517/14712598.2012.707181] [Citation(s) in RCA: 336] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Developing in vitro models for studying cell biology and cell physiology is of great importance to the fields of biotechnology, cancer research, drug discovery, toxicity testing, as well as the emerging fields of tissue engineering and regenerative medicine. Traditional two-dimensional (2D) methods of mammalian cell culture have several limitations and it is increasingly recognized that cells grown in a three-dimensional (3D) environment more closely represent normal cellular function due to the increased cell-to-cell interactions, and by mimicking the in vivo architecture of natural organs and tissues. AREAS COVERED In this review, we discuss the methods to form 3D multi-cellular spheroids, the advantages and limitations of these methods, and assays used to characterize the function of spheroids. The use of spheroids has led to many advances in basic cell sciences, including understanding cancer cell interactions, creating models for drug discovery and cancer metastasis, and they are being investigated as basic units for engineering tissue constructs. As so, this review will focus on contributions made to each of these fields using spheroid models. EXPERT OPINION Multi-cellular spheroids are rich in biological content and mimic better the in vivo environment than 2D cell culture. New technologies to form and analyze spheroids are rapidly increasing their adoption and expanding their applications.
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Affiliation(s)
- Toni-Marie Achilli
- Brown University, Department of Molecular Pharmacology, Physiology and Biotechnology, Providence, RI 02912, USA
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Liu Y, Buckley CT, Downey R, Mulhall KJ, Kelly DJ. The role of environmental factors in regulating the development of cartilaginous grafts engineered using osteoarthritic human infrapatellar fat pad-derived stem cells. Tissue Eng Part A 2012; 18:1531-41. [PMID: 22443147 DOI: 10.1089/ten.tea.2011.0575] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Engineering functional cartilaginous grafts using stem cells isolated from osteoarthritic human tissue is of fundamental importance if autologous tissue engineering strategies are to be used in the treatment of diseased articular cartilage. It has previously been demonstrated that human infrapatellar fat pad (IFP)-derived stem cells undergo chondrogenesis in pellet culture; however, the ability of such cells to generate functional cartilaginous grafts has not been adequately addressed. The objective of this study was to explore how environmental conditions regulate the functional development of cartilaginous constructs engineered using diseased human IFP-derived stem cells (FPSCs). FPSCs were observed to display a diminished chondrogenic potential upon encapsulation in a three-dimensional hydrogel compared with pellet culture, synthesizing significantly lower levels of glycosaminoglycan and collagen on a per cell basis. To engineer more functional cartilaginous grafts, we next explored whether additional biochemical and biophysical stimulations would enhance chondrogenesis within the hydrogels. Serum stimulation was observed to partially recover the diminished chondrogenic potential within hydrogel culture. Over 42 days, stem cells that had first been expanded in a low-oxygen environment proliferated extensively on the outer surface of the hydrogel in response to serum stimulation, assembling a dense type II collagen-positive cartilaginous tissue resembling that formed in pellet culture. The application of hydrostatic pressure did not further enhance extracellular matrix synthesis within the hydrogels, but did appear to alter the spatial accumulation of extracellular matrix leading to the formation of a more compact tissue with superior mechanically functionality. Further work is required in order to recapitulate the environmental conditions present during pellet culture within scaffolds or hydrogels in order to engineer more functional cartilaginous grafts using human osteoarthritic FPSCs.
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Affiliation(s)
- Yurong Liu
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
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146
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Khoshgoftar M, Wilson W, Ito K, van Donkelaar CC. The effect of tissue-engineered cartilage biomechanical and biochemical properties on its post-implantation mechanical behavior. Biomech Model Mechanobiol 2012; 12:43-54. [DOI: 10.1007/s10237-012-0380-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Accepted: 02/14/2012] [Indexed: 10/28/2022]
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Cheng T, Maddox NC, Wong AW, Rahnama R, Kuo AC. Comparison of gene expression patterns in articular cartilage and dedifferentiated articular chondrocytes. J Orthop Res 2012; 30:234-45. [PMID: 21809379 DOI: 10.1002/jor.21503] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 06/24/2011] [Indexed: 02/04/2023]
Abstract
During monolayer culture, articular chondrocytes dedifferentiate into fibroblast-like cells. The mechanisms underlying this process are poorly understood. We sought to further characterize dedifferentiation by identifying an extended panel of genes that distinguish articular cartilage from dedifferentiated chondrocytes. Thirty-nine candidate marker-genes were identified from previous studies on articular-cartilage gene-expression. Real-time PCR was used to evaluate the mRNA levels for these candidates in calf articular cartilage and dedifferentiated articular chondrocytes. Twenty-two of the candidate marker genes exhibited at least a two-fold difference in gene expression in the two cell types. Twelve of these genes had at least a ten-fold difference in gene expression. Tenascin C (TNC), type I collagen (COL1A1), and hypoxia-inducible factor 1 alpha (HIF1α) showed the highest relative expression levels in dedifferentiated chonodrocytes. Type II collagen (COL2A1), type XI collagen (COL11A2), and superficial zone protein (SZP) showed the highest relative expression levels in articular cartilage. In contrast to previous findings, fibromodulin mRNA, and protein levels were higher in dedifferentiated chondrocytes. Compared to smaller subsets of markers, this panel of 12 highly differentially expressed genes may more precisely distinguish articular cartilage from dedifferentiated chondrocytes. Since many of the genes up-regulated in dedifferentiated chondrocytes are also expressed during cartilage development, dedifferentiated chondrocytes may possess features of cartilage precursor cells.
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Affiliation(s)
- Tiffany Cheng
- Department of Orthopaedic Surgery, University of California, San Francisco and San Francisco Veterans Affairs Medical Center, San Francisco, USA
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148
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Responte DJ, Arzi B, Natoli RM, Hu JC, Athanasiou KA. Mechanisms underlying the synergistic enhancement of self-assembled neocartilage treated with chondroitinase-ABC and TGF-β1. Biomaterials 2012; 33:3187-94. [PMID: 22284584 DOI: 10.1016/j.biomaterials.2012.01.028] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 01/09/2012] [Indexed: 11/26/2022]
Abstract
Developing a platform for in vitro cartilage formation would enhance the study of cartilage development, pathogenesis, and regeneration. To improve neocartilage formation, our group developed a novel self-assembly process for articular chondrocytes, which has been improved in this study using a novel combination of catabolic and anabolic agents. TGF-β1 was applied in conjunction with the enzyme chondroitinase-ABC (C-ABC) to additively increase tensile properties and synergistically enhance collagen content. Additionally, microarray analysis indicated that TGF-β1 up-regulated MAPK signaling in contrast to C-ABC, which did not enrich genetic pathways. The lack of genetic signaling spurred investigation of the biophysical role of C-ABC, which showed that C-ABC treatment increased collagen fibril diameter and density. After four weeks of culture in nude mice, neocartilage exhibited stability and maturation. This study illustrated an innovative strategy for improving in vitro and in vivo articular cartilage formation and elucidated mechanisms underlying TGF-β1 and C-ABC treatment.
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Affiliation(s)
- Donald J Responte
- Department of Biomedical Engineering, University of California Davis, One Shields Ave, Davis, CA 95616, USA
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Sun Y, Responte D, Xie H, Liu J, Fatakdawala H, Hu J, Athanasiou KA, Marcu L. Nondestructive evaluation of tissue engineered articular cartilage using time-resolved fluorescence spectroscopy and ultrasound backscatter microscopy. Tissue Eng Part C Methods 2012; 18:215-26. [PMID: 22010819 DOI: 10.1089/ten.tec.2011.0343] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The goal of this study is to evaluate the ability of a bimodal technique integrating time-resolved fluorescence spectroscopy (TRFS) and ultrasound backscatter microscopy (UBM) for nondestructive detection of changes in the biochemical, structural, and mechanical properties of self-assembled engineered articular cartilage constructs. The cartilage constructs were treated with three chemical agents (collagenase, chondroitinase-ABC, and ribose) to induce changes in biochemical content (collagen and glycosaminoglycan [GAG]) of matured constructs (4 weeks); and to subsequently alter the mechanical properties of the construct. The biochemical changes were evaluated using TRFS. The microstructure and the thickness of the engineered cartilage samples were characterized by UBM. The optical and ultrasound results were validated against those acquired via conventional techniques including collagen and GAG quantification and measurement of construct stiffness. Current results demonstrated that a set of optical parameters (e.g., average fluorescence lifetime and decay constants) showed significant correlation (p<0.05) with biochemical and mechanical data. The high-resolution ultrasound images provided complementary cross-section information of the cartilage samples morphology. Therefore, the technique was capable of nondestructively evaluating the composition of extracellular matrix and the microstructure of engineered tissue, demonstrating great potential as an alternative to traditional destructive assays.
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Affiliation(s)
- Yang Sun
- Department of Biomedical Engineering, University of California Davis, Davis, CA, USA
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McNary SM, Athanasiou KA, Reddi AH. Engineering lubrication in articular cartilage. TISSUE ENGINEERING PART B-REVIEWS 2012; 18:88-100. [PMID: 21955119 DOI: 10.1089/ten.teb.2011.0394] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Despite continuous progress toward tissue engineering of functional articular cartilage, significant challenges still remain. Advances in morphogens, stem cells, and scaffolds have resulted in enhancement of the bulk mechanical properties of engineered constructs, but little attention has been paid to the surface mechanical properties. In the near future, engineered tissues will be able to withstand and support the physiological compressive and tensile forces in weight-bearing synovial joints such as the knee. However, there is an increasing realization that these tissue-engineered cartilage constructs will fail without the optimal frictional and wear properties present in native articular cartilage. These characteristics are critical to smooth, pain-free joint articulation and a long-lasting, durable cartilage surface. To achieve optimal tribological properties, engineered cartilage therapies will need to incorporate approaches and methods for functional lubrication. Steady progress in cartilage lubrication in native tissues has pushed the pendulum and warranted a shift in the articular cartilage tissue-engineering paradigm. Engineered tissues should be designed and developed to possess both tribological and mechanical properties mirroring natural cartilage. In this article, an overview of the biology and engineering of articular cartilage structure and cartilage lubrication will be presented. Salient progress in lubrication treatments such as tribosupplementation, pharmacological, and cell-based therapies will be covered. Finally, frictional assays such as the pin-on-disk tribometer will be addressed. Knowledge related to the elements of cartilage lubrication has progressed and, thus, an opportune moment is provided to leverage these advances at a critical step in the development of mechanically and tribologically robust, biomimetic tissue-engineered cartilage. This article is intended to serve as the first stepping stone toward future studies in functional tissue engineering of articular cartilage that begins to explore and incorporate methods of lubrication.
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Affiliation(s)
- Sean M McNary
- Department of Orthopaedic Surgery, Lawrence Ellison Center for Tissue Regeneration and Repair, School of Medicine, University of California, Davis, Sacramento, California, USA
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