1
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Pinto-Cardoso R, Bessa-Andrês C, Correia-de-Sá P, Bernardo Noronha-Matos J. Could hypoxia rehabilitate the osteochondral diseased interface? Lessons from the interplay of hypoxia and purinergic signals elsewhere. Biochem Pharmacol 2023:115646. [PMID: 37321413 DOI: 10.1016/j.bcp.2023.115646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/03/2023] [Accepted: 06/07/2023] [Indexed: 06/17/2023]
Abstract
The osteochondral unit comprises the articular cartilage (90%), subchondral bone (5%) and calcified cartilage (5%). All cells present at the osteochondral unit that is ultimately responsible for matrix production and osteochondral homeostasis, such as chondrocytes, osteoblasts, osteoclasts and osteocytes, can release adenine and/or uracil nucleotides to the local microenvironment. Nucleotides are released by these cells either constitutively or upon plasma membrane damage, mechanical stress or hypoxia conditions. Once in the extracellular space, endogenously released nucleotides can activate membrane-bound purinoceptors. Activation of these receptors is fine-tuning regulated by nucleotides' breakdown by enzymes of the ecto-nucleotidase cascade. Depending on the pathophysiological conditions, both the avascular cartilage and the subchondral bone subsist to significant changes in oxygen tension, which has a tremendous impact on tissue homeostasis. Cell stress due to hypoxic conditions directly influences the expression and activity of several purinergic signalling players, namely nucleotide release channels (e.g. Cx43), NTPDase enzymes and purinoceptors. This review gathers experimental evidence concerning the interplay between hypoxia and the purinergic signalling cascade contributing to osteochondral unit homeostasis. Reporting deviations to this relationship resulting from pathological alterations of articular joints may ultimately unravel novel therapeutic targets for osteochondral rehabilitation. At this point, one can only hypothesize how hypoxia mimetic conditions can be beneficial to the ex vivo expansion and differentiation of osteo- and chondro-progenitors for auto-transplantation and tissue regenerative purposes.
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Affiliation(s)
- Rui Pinto-Cardoso
- Laboratório de Farmacologia e Neurobiologia; Center for Drug Discovery and Innovative Medicines (MedInUP), Departamento de Imuno-Fisiologia e Farmacologia, Instituto de Ciências Biomédicas Abel Salazar - Universidade do Porto (ICBAS-UP)
| | - Catarina Bessa-Andrês
- Laboratório de Farmacologia e Neurobiologia; Center for Drug Discovery and Innovative Medicines (MedInUP), Departamento de Imuno-Fisiologia e Farmacologia, Instituto de Ciências Biomédicas Abel Salazar - Universidade do Porto (ICBAS-UP)
| | - Paulo Correia-de-Sá
- Laboratório de Farmacologia e Neurobiologia; Center for Drug Discovery and Innovative Medicines (MedInUP), Departamento de Imuno-Fisiologia e Farmacologia, Instituto de Ciências Biomédicas Abel Salazar - Universidade do Porto (ICBAS-UP)
| | - José Bernardo Noronha-Matos
- Laboratório de Farmacologia e Neurobiologia; Center for Drug Discovery and Innovative Medicines (MedInUP), Departamento de Imuno-Fisiologia e Farmacologia, Instituto de Ciências Biomédicas Abel Salazar - Universidade do Porto (ICBAS-UP).
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2
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Stevenson NL. The factory, the antenna and the scaffold: the three-way interplay between the Golgi, cilium and extracellular matrix underlying tissue function. Biol Open 2023; 12:287059. [PMID: 36802341 PMCID: PMC9986613 DOI: 10.1242/bio.059719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
The growth and development of healthy tissues is dependent on the construction of a highly specialised extracellular matrix (ECM) to provide support for cell growth and migration and to determine the biomechanical properties of the tissue. These scaffolds are composed of extensively glycosylated proteins which are secreted and assembled into well-ordered structures that can hydrate, mineralise, and store growth factors as required. The proteolytic processing and glycosylation of ECM components is vital to their function. These modifications are under the control of the Golgi apparatus, an intracellular factory hosting spatially organised, protein-modifying enzymes. Regulation also requires a cellular antenna, the cilium, which integrates extracellular growth signals and mechanical cues to inform ECM production. Consequently, mutations in either Golgi or ciliary genes frequently lead to connective tissue disorders. The individual importance of each of these organelles to ECM function is well-studied. However, emerging evidence points towards a more tightly linked system of interdependence between the Golgi, cilium and ECM. This review examines how the interplay between all three compartments underpins healthy tissue. As an example, it will look at several members of the golgin family of Golgi-resident proteins whose loss is detrimental to connective tissue function. This perspective will be important for many future studies looking to dissect the cause and effect of mutations impacting tissue integrity.
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Affiliation(s)
- Nicola L Stevenson
- Cell Biology Laboratories, School of Biochemistry, Faculty of Biomedical Sciences University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
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3
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Hodgkinson T, Amado IN, O'Brien FJ, Kennedy OD. The role of mechanobiology in bone and cartilage model systems in characterizing initiation and progression of osteoarthritis. APL Bioeng 2022. [DOI: 10.1063/5.0068277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Tom Hodgkinson
- Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Isabel N. Amado
- Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Fergal J. O'Brien
- Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland
- Advanced Materials Bio-Engineering Research Centre (AMBER), Dublin, Ireland
- Trinity Centre for Biomedical Engineering, Trinity College Dublin, Dublin, Ireland
| | - Oran D. Kennedy
- Department of Anatomy and Regenerative Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland
- Advanced Materials Bio-Engineering Research Centre (AMBER), Dublin, Ireland
- Trinity Centre for Biomedical Engineering, Trinity College Dublin, Dublin, Ireland
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4
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Mechanosignalling in cartilage: an emerging target for the treatment of osteoarthritis. Nat Rev Rheumatol 2021; 18:67-84. [PMID: 34934171 DOI: 10.1038/s41584-021-00724-w] [Citation(s) in RCA: 102] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2021] [Indexed: 12/12/2022]
Abstract
Mechanical stimuli have fundamental roles in articular cartilage during health and disease. Chondrocytes respond to the physical properties of the cartilage extracellular matrix (ECM) and the mechanical forces exerted on them during joint loading. In osteoarthritis (OA), catabolic processes degrade the functional ECM and the composition and viscoelastic properties of the ECM produced by chondrocytes are altered. The abnormal loading environment created by these alterations propagates cell dysfunction and inflammation. Chondrocytes sense their physical environment via an array of mechanosensitive receptors and channels that activate a complex network of downstream signalling pathways to regulate several cell processes central to OA pathology. Advances in understanding the complex roles of specific mechanosignalling mechanisms in healthy and OA cartilage have highlighted molecular processes that can be therapeutically targeted to interrupt pathological feedback loops. The potential for combining these mechanosignalling targets with the rapidly expanding field of smart mechanoresponsive biomaterials and delivery systems is an emerging paradigm in OA treatment. The continued advances in this field have the potential to enable restoration of healthy mechanical microenvironments and signalling through the development of precision therapeutics, mechanoregulated biomaterials and drug systems in the near future.
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5
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Larrañaga-Vera A, Marco-Bonilla M, Largo R, Herrero-Beaumont G, Mediero A, Cronstein B. ATP transporters in the joints. Purinergic Signal 2021; 17:591-605. [PMID: 34392490 PMCID: PMC8677878 DOI: 10.1007/s11302-021-09810-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 07/09/2021] [Indexed: 02/08/2023] Open
Abstract
Extracellular adenosine triphosphate (ATP) plays a central role in a wide variety of joint diseases. ATP is generated intracellularly, and the concentration of the extracellular ATP pool is determined by the regulation of its transport out of the cell. A variety of ATP transporters have been described, with connexins and pannexins the most commonly cited. Both form intercellular channels, known as gap junctions, that facilitate the transport of various small molecules between cells and mediate cell-cell communication. Connexins and pannexins also form pores, or hemichannels, that are permeable to certain molecules, including ATP. All joint tissues express one or more connexins and pannexins, and their expression is altered in some pathological conditions, such as osteoarthritis (OA) and rheumatoid arthritis (RA), indicating that they may be involved in the onset and progression of these pathologies. The aging of the global population, along with increases in the prevalence of obesity and metabolic dysfunction, is associated with a rising frequency of joint diseases along with the increased costs and burden of related illness. The modulation of connexins and pannexins represents an attractive therapeutic target in joint disease, but their complex regulation, their combination of gap-junction-dependent and -independent functions, and their interplay between gap junction and hemichannel formation are not yet fully elucidated. In this review, we try to shed light on the regulation of these proteins and their roles in ATP transport to the extracellular space in the context of joint disease, and specifically OA and RA.
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Affiliation(s)
- Ane Larrañaga-Vera
- Department of Medicine, Division of Translational Medicine, NYU Langone Health, New York, NY, USA
| | - Miguel Marco-Bonilla
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, 28040, Madrid, Spain
| | - Raquel Largo
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, 28040, Madrid, Spain
| | | | - Aránzazu Mediero
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, 28040, Madrid, Spain.
| | - Bruce Cronstein
- Department of Medicine, Division of Translational Medicine, NYU Langone Health, New York, NY, USA
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6
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Zhang K, Wang L, Liu Z, Geng B, Teng Y, Liu X, Yi Q, Yu D, Chen X, Zhao D, Xia Y. Mechanosensory and mechanotransductive processes mediated by ion channels in articular chondrocytes: Potential therapeutic targets for osteoarthritis. Channels (Austin) 2021; 15:339-359. [PMID: 33775217 PMCID: PMC8018402 DOI: 10.1080/19336950.2021.1903184] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 02/06/2023] Open
Abstract
Articular cartilage consists of an extracellular matrix including many proteins as well as embedded chondrocytes. Articular cartilage formation and function are influenced by mechanical forces. Hind limb unloading or simulated microgravity causes articular cartilage loss, suggesting the importance of the healthy mechanical environment in articular cartilage homeostasis and implying a significant role of appropriate mechanical stimulation in articular cartilage degeneration. Mechanosensitive ion channels participate in regulating the metabolism of articular chondrocytes, including matrix protein production and extracellular matrix synthesis. Mechanical stimuli, including fluid shear stress, stretch, compression and cell swelling and decreased mechanical conditions (such as simulated microgravity) can alter the membrane potential and regulate the metabolism of articular chondrocytes via transmembrane ion channel-induced ionic fluxes. This process includes Ca2+ influx and the resulting mobilization of Ca2+ that is due to massive released Ca2+ from stores, intracellular cation efflux and extracellular cation influx. This review brings together published information on mechanosensitive ion channels, such as stretch-activated channels (SACs), voltage-gated Ca2+ channels (VGCCs), large conductance Ca2+-activated K+ channels (BKCa channels), Ca2+-activated K+ channels (SKCa channels), voltage-activated H+ channels (VAHCs), acid sensing ion channels (ASICs), transient receptor potential (TRP) family channels, and piezo1/2 channels. Data based on epithelial sodium channels (ENaCs), purinergic receptors and N-methyl-d-aspartate (NMDA) receptors are also included. These channels mediate mechanoelectrical physiological processes essential for converting physical force signals into biological signals. The primary channel-mediated effects and signaling pathways regulated by these mechanosensitive ion channels can influence the progression of osteoarthritis during the mechanosensory and mechanoadaptive process of articular chondrocytes.
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Affiliation(s)
- Kun Zhang
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Lifu Wang
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Zhongcheng Liu
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Bin Geng
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Yuanjun Teng
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Xuening Liu
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Qiong Yi
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Dechen Yu
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Xiangyi Chen
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Dacheng Zhao
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
| | - Yayi Xia
- Department of Orthopedics, Orthopaedics Key Laboratory of Gansu Province, Lanzhou University Second Hospital, Lanzhou Gansu, China
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7
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Thompson CL, McFie M, Chapple JP, Beales P, Knight MM. Polycystin-2 Is Required for Chondrocyte Mechanotransduction and Traffics to the Primary Cilium in Response to Mechanical Stimulation. Int J Mol Sci 2021; 22:4313. [PMID: 33919210 PMCID: PMC8122406 DOI: 10.3390/ijms22094313] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/10/2021] [Accepted: 04/13/2021] [Indexed: 12/12/2022] Open
Abstract
Primary cilia and associated intraflagellar transport are essential for skeletal development, joint homeostasis, and the response to mechanical stimuli, although the mechanisms remain unclear. Polycystin-2 (PC2) is a member of the transient receptor potential polycystic (TRPP) family of cation channels, and together with Polycystin-1 (PC1), it has been implicated in cilia-mediated mechanotransduction in epithelial cells. The current study investigates the effect of mechanical stimulation on the localization of ciliary polycystins in chondrocytes and tests the hypothesis that they are required in chondrocyte mechanosignaling. Isolated chondrocytes were subjected to mechanical stimulation in the form of uniaxial cyclic tensile strain (CTS) in order to examine the effects on PC2 ciliary localization and matrix gene expression. In the absence of strain, PC2 localizes to the chondrocyte ciliary membrane and neither PC1 nor PC2 are required for ciliogenesis. Cartilage matrix gene expression (Acan, Col2a) is increased in response to 10% CTS. This response is inhibited by siRNA-mediated loss of PC1 or PC2 expression. PC2 ciliary localization requires PC1 and is increased in response to CTS. Increased PC2 cilia trafficking is dependent on the activation of transient receptor potential cation channel subfamily V member 4 (TRPV4) activation. Together, these findings demonstrate for the first time that polycystins are required for chondrocyte mechanotransduction and highlight the mechanosensitive cilia trafficking of PC2 as an important component of cilia-mediated mechanotransduction.
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Affiliation(s)
- Clare L. Thompson
- Centre for Predictive In Vitro Models, School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK; (M.M.); (M.M.K.)
| | - Megan McFie
- Centre for Predictive In Vitro Models, School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK; (M.M.); (M.M.K.)
| | - J. Paul Chapple
- Centre for Endocrinology, William Harvey Research Institute, School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK;
| | - Philip Beales
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK;
| | - Martin M. Knight
- Centre for Predictive In Vitro Models, School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK; (M.M.); (M.M.K.)
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8
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Gratal P, Lamuedra A, Medina JP, Bermejo-Álvarez I, Largo R, Herrero-Beaumont G, Mediero A. Purinergic System Signaling in Metainflammation-Associated Osteoarthritis. Front Med (Lausanne) 2020; 7:506. [PMID: 32984382 PMCID: PMC7485330 DOI: 10.3389/fmed.2020.00506] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 07/22/2020] [Indexed: 12/18/2022] Open
Abstract
Inflammation triggered by metabolic imbalance, also called metainflammation, is low-grade inflammation caused by the components involved in metabolic syndrome (MetS), including central obesity and impaired glucose tolerance. This phenomenon is mainly due to excess nutrients and energy, and it contributes to the pathogenesis of osteoarthritis (OA). OA is characterized by the progressive degeneration of articular cartilage, which suffers erosion and progressively becomes thinner. Purinergic signaling is involved in several physiological and pathological processes, such as cell proliferation in development and tissue regeneration, neurotransmission and inflammation. Adenosine and ATP receptors, and other members of the signaling pathway, such as AMP-activated protein kinase (AMPK), are involved in obesity, type 2 diabetes (T2D) and OA progression. In this review, we focus on purinergic regulation in osteoarthritic cartilage and how different components of MetS, such as obesity and T2D, modulate the purinergic system in OA. In that regard, we describe the critical role in this disease of receptors, such as adenosine A2A receptor (A2AR) and ATP P2X7 receptor. Finally, we also assess how nucleotides regulate the inflammasome in OA.
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Affiliation(s)
- Paula Gratal
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, Madrid, Spain
| | - Ana Lamuedra
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, Madrid, Spain
| | - Juan Pablo Medina
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, Madrid, Spain
| | | | - Raquel Largo
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, Madrid, Spain
| | | | - Aránzazu Mediero
- Bone and Joint Research Unit, IIS-Fundación Jiménez Díaz UAM, Madrid, Spain
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9
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Zhao Z, Li Y, Wang M, Zhao S, Zhao Z, Fang J. Mechanotransduction pathways in the regulation of cartilage chondrocyte homoeostasis. J Cell Mol Med 2020; 24:5408-5419. [PMID: 32237113 PMCID: PMC7214151 DOI: 10.1111/jcmm.15204] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 03/01/2020] [Accepted: 03/03/2020] [Indexed: 02/05/2023] Open
Abstract
Mechanical stress plays a critical role in cartilage development and homoeostasis. Chondrocytes are surrounded by a narrow pericellular matrix (PCM), which absorbs dynamic and static forces and transmits them to the chondrocyte surface. Recent studies have demonstrated that molecular components, including perlecan, collagen and hyaluronan, provide distinct physical properties for the PCM and maintain the essential microenvironment of chondrocytes. These physical signals are sensed by receptors and molecules located in the cell membrane, such as Ca2+ channels, the primary cilium and integrins, and a series of downstream molecular pathways are involved in mechanotransduction in cartilage. All mechanoreceptors convert outside signals into chemical and biological signals, which then regulate transcription in chondrocytes in response to mechanical stresses. This review highlights recent progress and focuses on the function of the PCM and cell surface molecules in chondrocyte mechanotransduction. Emerging understanding of the cellular and molecular mechanisms that regulate mechanotransduction will provide new insights into osteoarthritis pathogenesis and precision strategies that could be used in its treatment.
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Affiliation(s)
- Zhenxing Zhao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yifei Li
- Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China.,Ministry of Education Key Laboratory of Women and Children's Diseases and Birth Defects, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Mengjiao Wang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Sen Zhao
- Department of Orthodontics, School of Dentistry, Chonbuk National University, Jeonju, Korea
| | - Zhihe Zhao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jie Fang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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10
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Corciulo C, Cronstein BN. Signaling of the Purinergic System in the Joint. Front Pharmacol 2020; 10:1591. [PMID: 32038258 PMCID: PMC6993121 DOI: 10.3389/fphar.2019.01591] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 12/09/2019] [Indexed: 12/15/2022] Open
Abstract
The joint is a complex anatomical structure consisting of different tissues, each with a particular feature, playing together to give mobility and stability at the body. All the joints have a similar composition including cartilage for reducing the friction of the movement and protecting the underlying bone, a synovial membrane that produces synovial fluid to lubricate the joint, ligaments to limit joint movement, and tendons for the interaction with muscles. Direct or indirect damage of one or more of the tissues forming the joint is the foundation of different pathological conditions. Many molecular mechanisms are involved in maintaining the joint homeostasis as well as in triggering disease development. The molecular pathway activated by the purinergic system is one of them.The purinergic signaling defines a group of receptors and intermembrane channels activated by adenosine, adenosine diphosphate, adenosine 5’-triphosphate, uridine triphosphate, and uridine diphosphate. It has been largely described as a modulator of many physiological and pathological conditions including rheumatic diseases. Here we will give an overview of the purinergic system in the joint describing its expression and function in the synovium, cartilage, ligament, tendon, and bone with a therapeutic perspective.
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Affiliation(s)
- Carmen Corciulo
- Division of Translational Medicine, Department of Medicine, NYU School of Medicine, New York, NY, United States.,Krefting Research Centre-Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Bruce N Cronstein
- Division of Translational Medicine, Department of Medicine, NYU School of Medicine, New York, NY, United States.,Division of Rheumatology, Department of Medicine, NYU School of Medicine, New York, NY, United States
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11
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Regulation of the Extracellular Matrix by Ciliary Machinery. Cells 2020; 9:cells9020278. [PMID: 31979260 PMCID: PMC7072529 DOI: 10.3390/cells9020278] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/13/2020] [Accepted: 01/19/2020] [Indexed: 12/14/2022] Open
Abstract
The primary cilium is an organelle involved in cellular signalling. Mutations affecting proteins involved in cilia assembly or function result in diseases known as ciliopathies, which cause a wide variety of phenotypes across multiple tissues. These mutations disrupt various cellular processes, including regulation of the extracellular matrix. The matrix is important for maintaining tissue homeostasis through influencing cell behaviour and providing structural support; therefore, the matrix changes observed in ciliopathies have been implicated in the pathogenesis of these diseases. Whilst many studies have associated the cilium with processes that regulate the matrix, exactly how these matrix changes arise is not well characterised. This review aims to bring together the direct and indirect evidence for ciliary regulation of matrix, in order to summarise the possible mechanisms by which the ciliary machinery could regulate the composition, secretion, remodelling and organisation of the matrix.
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12
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Parisi C, Chandaria VV, Nowlan NC. Blocking mechanosensitive ion channels eliminates the effects of applied mechanical loading on chick joint morphogenesis. Philos Trans R Soc Lond B Biol Sci 2018; 373:rstb.2017.0317. [PMID: 30249769 PMCID: PMC6158207 DOI: 10.1098/rstb.2017.0317] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/02/2018] [Indexed: 11/12/2022] Open
Abstract
Abnormalities in joint shape are increasingly considered a critical risk factor for developing osteoarthritis in life. It has been shown that mechanical forces during prenatal development, particularly those due to fetal movements, play a fundamental role in joint morphogenesis. However, how mechanical stimuli are sensed or transduced in developing joint tissues is unclear. Stretch-activated and voltage-gated calcium ion channels have been shown to be involved in the mechanoregulation of chondrocytes in vitro. In this study, we analyse, for the first time, how blocking these ion channels influences the effects of mechanical loading on chick joint morphogenesis. Using in vitro culture of embryonic chick hindlimb explants in a mechanostimulation bioreactor, we block stretch-activated and voltage-gated ion channels using, respectively, gadolinium chloride and nifedipine. We find that the administration of high doses of either drug largely removed the effects of mechanical stimulation on growth and shape development in vitro, while neither drug had any effect in static cultures. This study demonstrates that, during joint morphogenesis, mechanical cues are transduced—at least in part—through mechanosensitive calcium ion channels, advancing our understanding of cartilage development and mechanotransduction. This article is part of the Theo Murphy meeting issue ‘Mechanics of development’.
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Affiliation(s)
- Cristian Parisi
- Department of Bioengineering, Faculty of Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Vikesh V Chandaria
- Department of Bioengineering, Faculty of Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Niamh C Nowlan
- Department of Bioengineering, Faculty of Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
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13
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Abstract
Mechanical loading of the intervertebral disc (IVD) initiates cell-mediated remodeling events that contribute to disc degeneration. Cells of the IVD, nucleus pulposus (NP) and anulus fibrosus (AF), will exhibit various responses to different mechanical stimuli which appear to be highly dependent on loading type, magnitude, duration, and anatomic zone of cell origin. Cells of the NP, the innermost region of the disc, exhibit an anabolic response to low-moderate magnitudes of static compression, osmotic pressure, or hydrostatic pressure, while higher magnitudes promote a catabolic response marked by increased protease expression and activity. Cells of the outer AF are responsive to physical forces in a manner that depends on frequency and magnitude, as are cells of the NP, though they experience different forces, deformations, pressure, and osmotic pressure in vivo. Much remains to be understood of the mechanotransduction pathways that regulate IVD cell responses to loading, including responses to specific stimuli and also differences among cell types. There is evidence that cytoskeletal remodeling and receptor-mediated signaling are important mechanotransduction events that can regulate downstream effects like gene expression and posttranslational biosynthesis, all of which may influence phenotype and bioactivity. These and other mechanotransduction events will be regulated by known and to-be-discovered cell-matrix and cell-cell interactions, and depend on composition of extracellular matrix ligands for cell interaction, matrix stiffness, and the phenotype of the cells themselves. Here, we present a review of the current knowledge of the role of mechanical stimuli and the impact upon the cellular response to loading and changes that occur with aging and degeneration of the IVD.
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Affiliation(s)
- Bailey V Fearing
- Department of Biomedical Engineering & Orthopedic Surgery, Washington University in St. Louis, St. Louis, Missouri
| | - Paula A Hernandez
- Department of Orthopaedic Surgery, University of Texas Southwestern, Dallas, Texas
| | - Lori A Setton
- Department of Biomedical Engineering & Orthopedic Surgery, Washington University in St. Louis, St. Louis, Missouri
| | - Nadeen O Chahine
- Department of Orthopedic Surgery & Biomedical Engineering, Columbia University, New York, New York
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14
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Steward AJ, Kelly DJ, Wagner DR. Purinergic Signaling Regulates the Transforming Growth Factor-β3-Induced Chondrogenic Response of Mesenchymal Stem Cells to Hydrostatic Pressure. Tissue Eng Part A 2017; 22:831-9. [PMID: 27137792 DOI: 10.1089/ten.tea.2015.0047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Although hydrostatic pressure (HP) is known to regulate chondrogenic differentiation of mesenchymal stromal/stem cells (MSCs), improved insight into the mechanotransduction of HP may form the basis for novel tissue engineering strategies. Previously, we demonstrated that matrix stiffness and calcium ion (Ca(++)) mobility regulate the mechanotransduction of HP; however, the mechanisms, by which these Ca(++) signaling pathways are initiated, are currently unknown. The purinergic pathway, in which adenosine triphosphate (ATP) is released and activates P-receptors to initiate Ca(++) signaling, plays a key role in the mechanotransduction of compression, but has yet to be investigated with regard to HP. Therefore, the objective of this study was to investigate the interplay between purinergic signaling, matrix stiffness, and the chondrogenic response of MSCs to HP. Porcine bone marrow-derived MSCs were seeded into soft or stiff agarose hydrogels and subjected to HP (10 MPa at 1 Hz for 4 h/d for 21 days) or kept in free swelling conditions. Stiff constructs were incubated with pharmacological inhibitors of extracellular ATP, P2 receptors, or hemichannels, or without any inhibitors as a control. As with other loading modalities, HP significantly increased ATP release in the control group; however, inhibition of hemichannels completely abrogated this response. The increase in sulfated glycosaminoglycan (sGAG) synthesis and vimentin reorganization observed in the control group in response to HP was suppressed in the presence of all three inhibitors, suggesting that purinergic signaling is involved in the mechanoresponse of MSCs to HP. Interestingly, ATP was released from both soft and stiff hydrogels in response to HP, but HP only enhanced chondrogenesis in the stiff hydrogels, indicating that matrix stiffness may act downstream of purinergic signaling to regulate the mechanoresponse of MSCs to HP. Addition of exogenous ATP did not replicate the effects of HP on chondrogenesis, suggesting that mechanisms other than purinergic signaling also regulate the response of MSCs to HP.
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Affiliation(s)
- Andrew J Steward
- 1 Bioengineering Graduate Program, Department of Aerospace and Mechanical Engineering, University of Notre Dame , Notre Dame, Indiana.,2 Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute , Trinity College Dublin, Dublin, Ireland
| | - Daniel J Kelly
- 2 Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute , Trinity College Dublin, Dublin, Ireland .,3 Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin , Dublin, Ireland .,4 Advanced Materials and Bioengineering Research Centre (AMBER), Trinity College Dublin , Dublin, Ireland
| | - Diane R Wagner
- 5 Department of Mechanical Engineering, Indiana University-Purdue University Indianapolis , Indianapolis, Indiana.,6 Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis , Indianapolis, Indiana
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Decoding the intervertebral disc: Unravelling the complexities of cell phenotypes and pathways associated with degeneration and mechanotransduction. Semin Cell Dev Biol 2016; 62:94-103. [PMID: 27208724 DOI: 10.1016/j.semcdb.2016.05.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 05/17/2016] [Indexed: 12/20/2022]
Abstract
Back pain is the most common cause of pain and disability worldwide. While its etiology remains unknown, it is typically associated with intervertebral disc (IVD) degeneration. Despite the prevalence of back pain, relatively little is known about the specific cellular pathways and mechanisms that contribute to the development, function and degeneration of the IVD. Consequently, current treatments for back pain are largely limited to symptomatic interventions. However, major progress is being made in multiple research directions to unravel the biology and pathology of the IVD, raising hope that effective disease-modifying interventions will soon be developed. In this review, we will discuss our current knowledge and gaps in knowledge on the developmental origin of the IVD, the phenotype of the distinct cell types found within the IVD tissues, molecular targets in IVD degeneration identified using bioinformatics strategies, and mechanotransduction pathways that influence IVD cell fate and function.
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Zhou Q, Xu C, Cheng X, Liu Y, Yue M, Hu M, Luo D, Niu Y, Ouyang H, Ji J, Hu H. Platelets promote cartilage repair and chondrocyte proliferation via ADP in a rodent model of osteoarthritis. Platelets 2015; 27:212-22. [PMID: 26325015 DOI: 10.3109/09537104.2015.1075493] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Osteoarthritis (OA) is the most common age-related degenerative joint disease and platelet-rich plasma (PRP) has been shown to be beneficial in OA. Therefore, in this study, we aimed to investigate the effects of platelets on chondrocytes and the underlying mechanisms. Anabolic and catabolic activity and the proliferation rate of chondrocytes were evaluated after co-culture with platelets. Chondrocyte gene expression was measured by real-time PCR. Chondrocyte protein expression and phosphorylation were measured by western blot. Chondrocytes treated with or without platelets were transplanted into a rat model of OA induced by intra-articular injection of monosodium iodoacetate and the repair of articular cartilage was evaluated macroscopically and histologically. Platelets significantly promoted the proliferation of chondrocytes, while mildly influencing anabolic and catabolic activity. Chondrocytes co-cultured with platelets showed significantly increased production of bone morphogenetic protein 7 (BMP7). The autocrine/paracrine effect of BMP7 was responsible for the increased proliferation of chondrocytes, via the ERK/CDK1/cyclin B1 signaling pathway. Transplantation of platelet-treated chondrocytes showed better cartilage repair in the OA model. Platelet-derived ADP was identified as the major mediator to promote the production of BMP7 and the proliferation of chondrocytes, through the ADP receptor P2Y1. Finally, direct injection of α,β-methyleneadenosine-5'-diphosphate into OA joints also enhanced cartilage repair. This study has identified that platelet-derived ADP, but not ATP, is the key mediator for platelet-promoted chondrocyte proliferation and cartilage repair in osteoarthritis. This finding may provide a key explanation for the therapeutic effect of platelets in OA and help shaping a strategy to improve OA therapy.
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Affiliation(s)
- Qi Zhou
- a Department of Pathology and Pathophysiology , Zhejiang University School of Medicine , Hangzhou , China
| | - Chunhua Xu
- a Department of Pathology and Pathophysiology , Zhejiang University School of Medicine , Hangzhou , China
| | - Xingyao Cheng
- b Affiliated Lishui Hospital of Zhejiang University , Lishui , China
| | - Yangyang Liu
- a Department of Pathology and Pathophysiology , Zhejiang University School of Medicine , Hangzhou , China
| | - Ming Yue
- a Department of Pathology and Pathophysiology , Zhejiang University School of Medicine , Hangzhou , China
| | - Mengjiao Hu
- a Department of Pathology and Pathophysiology , Zhejiang University School of Medicine , Hangzhou , China
| | - Dongjiao Luo
- a Department of Pathology and Pathophysiology , Zhejiang University School of Medicine , Hangzhou , China
| | - Yuxi Niu
- a Department of Pathology and Pathophysiology , Zhejiang University School of Medicine , Hangzhou , China
| | - Hongwei Ouyang
- c Center for Stem Cell and Tissue Engineering, Zhejiang University School of Medicine , Hangzhou , Zhejiang , China , and
| | - Jiansong Ji
- b Affiliated Lishui Hospital of Zhejiang University , Lishui , China
| | - Hu Hu
- a Department of Pathology and Pathophysiology , Zhejiang University School of Medicine , Hangzhou , China .,d Zhejiang Key Laboratory for Disease Proteomics , Zhejiang , China
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17
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Abstract
Accumulating evidence now suggests that purinergic signalling exerts significant regulatory effects in the musculoskeletal system. In particular, it has emerged that extracellular nucleotides are key regulators of bone cell differentiation, survival and function. This review discusses our current understanding of the direct effects of purinergic signalling in bone, cartilage and muscle.
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Affiliation(s)
- Isabel R Orriss
- Department of Comparative Biomedical Sciences, Royal Veterinary College, Royal College Street, London NW1 0TU, United Kingdom.
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18
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Gonzales S, Wang C, Levene H, Cheung HS, Huang CYC. ATP promotes extracellular matrix biosynthesis of intervertebral disc cells. Cell Tissue Res 2014; 359:635-642. [PMID: 25407524 DOI: 10.1007/s00441-014-2042-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 10/16/2014] [Indexed: 01/07/2023]
Abstract
We have recently found a high accumulation of extracellular adenosine triphosphate (ATP) in the center of healthy porcine intervertebral discs (IVD). Since ATP is a powerful extracellular signaling molecule, extracellular ATP accumulation might regulate biological activities in the IVD. The objective of this study was therefore to investigate the effects of extracellular ATP on the extracellular matrix (ECM) biosynthesis of porcine IVD cells isolated from two distinct anatomical regions: the annulus fibrosus (AF) and nucleus pulposus (NP). ATP treatment significantly promotes ECM deposition and corresponding gene expression (aggrecan and type II collagen) by both cell types in three-dimensional agarose culture. A significant increase in ECM accumulation has been found in AF cells at a lower ATP treatment level (20 μM) compared with NP cells (100 μM), indicating that AF cells are more sensitive to extracellular ATP than NP cells. NP cells also exhibit higher ECM accumulation and intracellular ATP than AF cells under control and treatment conditions, suggesting that NP cells are intrinsically more metabolically active. Moreover, ATP treatment also augments the intracellular ATP level in NP and AF cells. Our findings suggest that extracellular ATP not only promotes ECM biosynthesis via a molecular pathway, but also increases energy supply to fuel that process.
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Affiliation(s)
- Silvia Gonzales
- Department of Biomedical Engineering, College of Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL, 33124-0621, USA
| | - Chong Wang
- Department of Biomedical Engineering, College of Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL, 33124-0621, USA
| | - Howard Levene
- Department of Neurological Surgery, University of Miami, Miami, FL, 33136, USA
| | - Herman S Cheung
- Department of Biomedical Engineering, College of Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL, 33124-0621, USA
- Geriatric Research, Education and Clinical Center, Miami Veterans Affairs Medical Center, Miami, FL, 33125, USA
| | - Chun-Yuh Charles Huang
- Department of Biomedical Engineering, College of Engineering, University of Miami, P.O. Box 248294, Coral Gables, FL, 33124-0621, USA.
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19
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The role of extracellular ATP-mediated purinergic signaling in bone, cartilage, and tooth tissue. J Oral Biosci 2014. [DOI: 10.1016/j.job.2014.07.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Burnstock G, Arnett TR, Orriss IR. Purinergic signalling in the musculoskeletal system. Purinergic Signal 2013; 9:541-72. [PMID: 23943493 PMCID: PMC3889393 DOI: 10.1007/s11302-013-9381-4] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 07/12/2013] [Indexed: 12/11/2022] Open
Abstract
It is now widely recognised that extracellular nucleotides, signalling via purinergic receptors, participate in numerous biological processes in most tissues. It has become evident that extracellular nucleotides have significant regulatory effects in the musculoskeletal system. In early development, ATP released from motor nerves along with acetylcholine acts as a cotransmitter in neuromuscular transmission; in mature animals, ATP functions as a neuromodulator. Purinergic receptors expressed by skeletal muscle and satellite cells play important pathophysiological roles in their development or repair. In many cell types, expression of purinergic receptors is often dependent on differentiation. For example, sequential expression of P2X5, P2Y1 and P2X2 receptors occurs during muscle regeneration in the mdx model of muscular dystrophy. In bone and cartilage cells, the functional effects of purinergic signalling appear to be largely negative. ATP stimulates the formation and activation of osteoclasts, the bone-destroying cells. Another role appears to be as a potent local inhibitor of mineralisation. In osteoblasts, the bone-forming cells, ATP acts via P2 receptors to limit bone mineralisation by inhibiting alkaline phosphatase expression and activity. Extracellular ATP additionally exerts significant effects on mineralisation via its hydrolysis product, pyrophosphate. Evidence now suggests that purinergic signalling is potentially important in several bone and joint disorders including osteoporosis, rheumatoid arthritis and cancers. Strategies for future musculoskeletal therapies might involve modulation of purinergic receptor function or of the ecto-nucleotidases responsible for ATP breakdown or ATP transport inhibitors.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK,
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21
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Gadjanski I, Yodmuang S, Spiller K, Bhumiratana S, Vunjak-Novakovic G. Supplementation of exogenous adenosine 5'-triphosphate enhances mechanical properties of 3D cell-agarose constructs for cartilage tissue engineering. Tissue Eng Part A 2013; 19:2188-200. [PMID: 23651296 DOI: 10.1089/ten.tea.2012.0352] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Formation of tissue-engineered cartilage is greatly enhanced by mechanical stimulation. However, direct mechanical stimulation is not always a suitable method, and the utilization of mechanisms underlying mechanotransduction might allow for a highly effective and less aggressive alternate means of stimulation. In particular, the purinergic, adenosine 5'-triphosphate (ATP)-mediated signaling pathway is strongly implicated in mechanotransduction within the articular cartilage. We investigated the effects of transient and continuous exogenous ATP supplementation on mechanical properties of cartilaginous constructs engineered using bovine chondrocytes and human mesenchymal stem cells (hMSCs) encapsulated in an agarose hydrogel. For both cell types, we have observed significant increases in equilibrium and dynamic compressive moduli after transient ATP treatment applied in the fourth week of cultivation. Continuous ATP treatment over 4 weeks of culture only slightly improved the mechanical properties of the constructs, without major changes in the total glycosaminoglycan (GAG) and collagen content. Structure-function analyses showed that transiently ATP-treated constructs, and in particular those based on hMSCs, had the highest level of correlation between compositional and mechanical properties. Transiently treated groups showed intense staining of the territorial matrix for GAGs and collagen type II. These results indicate that transient ATP treatment can improve functional mechanical properties of cartilaginous constructs based on chondrogenic cells and agarose hydrogels, possibly by improving the structural organization of the bulk phase and territorial extracellular matrix (ECM), that is, by increasing correlation slopes between the content of the ECM components (GAG, collagen) and mechanical properties of the construct.
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Affiliation(s)
- Ivana Gadjanski
- Department of Biomedical Engineering, Columbia University, 622 West 168th Street, New York, NY 10032, USA
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22
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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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23
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Chen J, Irianto J, Inamdar S, Pravincumar P, Lee DA, Bader DL, Knight MM. Cell mechanics, structure, and function are regulated by the stiffness of the three-dimensional microenvironment. Biophys J 2013; 103:1188-97. [PMID: 22995491 DOI: 10.1016/j.bpj.2012.07.054] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 07/06/2012] [Accepted: 07/27/2012] [Indexed: 11/17/2022] Open
Abstract
This study adopts a combined computational and experimental approach to determine the mechanical, structural, and metabolic properties of isolated chondrocytes cultured within three-dimensional hydrogels. A series of linear elastic and hyperelastic finite-element models demonstrated that chondrocytes cultured for 24 h in gels for which the relaxation modulus is <5 kPa exhibit a cellular Young's modulus of ∼5 kPa. This is notably greater than that reported for isolated chondrocytes in suspension. The increase in cell modulus occurs over a 24-h period and is associated with an increase in the organization of the cortical actin cytoskeleton, which is known to regulate cell mechanics. However, there was a reduction in chromatin condensation, suggesting that changes in the nucleus mechanics may not be involved. Comparison of cells in 1% and 3% agarose showed that cells in the stiffer gels rapidly develop a higher Young's modulus of ∼20 kPa, sixfold greater than that observed in the softer gels. This was associated with higher levels of actin organization and chromatin condensation, but only after 24 h in culture. Further studies revealed that cells in stiffer gels synthesize less extracellular matrix over a 28-day culture period. Hence, this study demonstrates that the properties of the three-dimensional microenvironment regulate the mechanical, structural, and metabolic properties of living cells.
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Affiliation(s)
- J Chen
- Institute of Bioengineering, School of Engineering and Materials Science, Queen Mary University of London, London, United Kingdom
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24
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Wann AKT, Zuo N, Haycraft CJ, Jensen CG, Poole CA, McGlashan SR, Knight MM. Primary cilia mediate mechanotransduction through control of ATP-induced Ca2+ signaling in compressed chondrocytes. FASEB J 2012; 26:1663-71. [PMID: 22223751 DOI: 10.1096/fj.11-193649] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We investigated the role of the chondrocyte primary cilium in mechanotransduction events related to cartilage extracellular matrix synthesis. We generated conditionally immortalized wild-type (WT) and IFT88(orpk) (ORPK) mutant chondrocytes that lack primary cilia and assessed intracellular Ca(2+) signaling, extracellular matrix synthesis, and ATP release in response to physiologically relevant compressive strains in a 3-dimensional chondrocyte culture system. All conditions were compared to unloaded controls. We found that cilia were required for compression-induced Ca(2+) signaling mediated by ATP release, and an associated up-regulation of aggrecan mRNA and sulfated glycosaminosglycan secretion. However, chondrocyte cilia were not the initial mechanoreceptors, since both WT and ORPK cells showed mechanically induced ATP release. Rather, we found that primary cilia were required for downstream ATP reception, since ORPK cells did not elicit a Ca(2+) response to exogenous ATP even though WT and ORPK cells express similar levels of purine receptors. We suggest that purinergic Ca(2+) signaling may be regulated by polycystin-1, since ORPK cells only expressed the C-terminal tail. This is the first study to demonstrate that primary cilia are essential organelles for cartilage mechanotransduction, as well as identifying a novel role for primary cilia not previously reported in any other cell type, namely cilia-mediated control of ATP reception.
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Affiliation(s)
- Angus K T Wann
- School of Engineering and Materials Science, Queen Mary University of London, London, UK
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Fernando H, Czamanski J, Yuan TY, Gu W, Abdi S, Huang CY. Mechanical loading affects the energy metabolism of intervertebral disc cells. J Orthop Res 2011; 29:1634-41. [PMID: 21484859 PMCID: PMC3137745 DOI: 10.1002/jor.21430] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2010] [Accepted: 03/15/2011] [Indexed: 02/04/2023]
Abstract
Research has shown that mechanical loading affects matrix biosynthesis of intervertebral disc (IVD) cells; however, the pathway(s) to this effect is currently unknown. Cellular matrix biosynthesis is an energy demanding process. The objective of this study was to investigate the effects of static and dynamic compressive loading on energy metabolism of IVD cells. Porcine annulus fibrosus (AF) and nucleus pulposus (NP) cells seeded in 2% agarose were used in this experiment. Experimental groups included 15% static compression and 0.1 and 1 Hz dynamic compression at 15% strain magnitude for 4 h. ATP, lactate, glucose, and nitric oxide (NO) contents in culture media, and ATP content in cell-agarose construct were measured using biochemical assays. While the total ATP content of AF cells was promoted by static and dynamic loading, only 1 Hz dynamic loading increased total ATP content of NP cells. Increases in lactate production and glucose consumption of AF cells suggest that ATP production via glycolysis is promoted by dynamic compression. ATP release and NO production of AF and NP cells were significantly increased by dynamic loading. Thus, this study clearly illustrates that static and dynamic compressive loading affect IVD cell energy production while cellular responses to mechanical loading were both cell type and compression type dependent.
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Affiliation(s)
- H.N. Fernando
- Stem Cell and Mechanobiology Lab, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida 33146, USA
| | - J. Czamanski
- Stem Cell and Mechanobiology Lab, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida 33146, USA
| | - T.-Y. Yuan
- Stem Cell and Mechanobiology Lab, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida 33146, USA, Tissue Biomechanics Lab, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida 33146, USA
| | - W.Y. Gu
- Tissue Biomechanics Lab, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida 33146, USA
| | - S. Abdi
- Department of Anesthesiology, Critical Care and Pain Medicine, BIDMC, Harvard Medical School, Boston, MA
| | - C.-Y.C. Huang
- Stem Cell and Mechanobiology Lab, Dept of Biomedical Engineering, University of Miami, Coral Gables, Florida 33146, USA
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Biomechanical influence of cartilage homeostasis in health and disease. ARTHRITIS 2011; 2011:979032. [PMID: 22046527 PMCID: PMC3196252 DOI: 10.1155/2011/979032] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 06/26/2011] [Indexed: 11/30/2022]
Abstract
There is an urgent demand for long term solutions to improve osteoarthritis treatments in the ageing population. There are drugs that control the pain but none that stop the progression of the disease in a safe and efficient way. Increased intervention efforts, augmented by early diagnosis and integrated biophysical therapies are therefore needed. Unfortunately, progress has been hampered due to the wide variety of experimental models which examine the effect of mechanical stimuli and inflammatory mediators on signal transduction pathways. Our understanding of the early mechanopathophysiology is poor, particularly the way in which mechanical stimuli influences cell function and regulates matrix synthesis. This makes it difficult to identify reliable targets and design new therapies. In addition, the effect of mechanical loading on matrix turnover is dependent on the nature of the mechanical stimulus. Accumulating evidence suggests that moderate mechanical loading helps to maintain cartilage integrity with a low turnover of matrix constituents. In contrast, nonphysiological mechanical signals are associated with increased cartilage damage and degenerative changes. This review will discuss the pathways regulated by compressive loading regimes and inflammatory signals in animal and in vitro 3D models. Identification of the chondroprotective pathways will reveal novel targets for osteoarthritis treatments.
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Biomechanical signals and the C-type natriuretic peptide counteract catabolic activities induced by IL-1β in chondrocyte/agarose constructs. Arthritis Res Ther 2011; 13:R145. [PMID: 21914170 PMCID: PMC3308073 DOI: 10.1186/ar3459] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 08/02/2011] [Accepted: 09/13/2011] [Indexed: 11/10/2022] Open
Abstract
Introduction The present study examined the effect of C-type natriuretic peptide (CNP) on the anabolic and catabolic activities in chondrocyte/agarose constructs subjected to dynamic compression. Methods Constructs were cultured under free-swelling conditions or subjected to dynamic compression with low (0.1 to 100 pM) or high concentrations (1 to 1,000 nM) of CNP, interleukin-1β (IL-1β), and/or KT-5823 (inhibits cyclic GMP-dependent protein kinase II (PKGII)). Anabolic and catabolic activities were assessed as follows: nitric oxide (NO) and prostaglandin E2 (PGE2) release, and [3H]-thymidine and 35SO4 incorporation were quantified by using biochemical assays. Gene expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), aggrecan, and collagen type II were assessed with real-time quantitative PCR (qPCR). Two-way ANOVA and the post hoc Bonferroni-corrected t tests were used to examine data. Results CNP reduced NO and PGE2 release and partially restored [3H]-thymidine and 35SO4 incorporation in constructs cultured with IL-1β. The response was dependent on the concentration of CNP, such that 100 pM increased [3H]-thymidine incorporation (P < 0.001). This is in contrast to 35SO4 incorporation, which was enhanced with 100 or 1000 nM CNP in the presence and absence of IL-1β (P < 0.001). Stimulation by both dynamic compression and CNP and/or the PKGII inhibitor further reduced NO and PGE2 release and restored [3H]-thymidine and 35SO4 incorporation. In the presence and absence of IL-1β, the magnitude of stimulation for [3H]-thymidine and 35SO4 incorporation by dynamic compression was dependent on the concentration of CNP and the response was inhibited with the PKGII inhibitor. In addition, stimulation by CNP and/or dynamic compression reduced IL-1β-induced iNOS and COX-2 expression and restored aggrecan and collagen type II expression. The catabolic response was not further influenced with the PKGII inhibitor in IL-1β-treated constructs. Conclusions Treatment with CNP and dynamic compression increased anabolic activities and blocked catabolic effects induced by IL-1β. The anabolic response was PKGII mediated and raises important questions about the molecular mechanisms of CNP with mechanical signals in cartilage. Therapeutic agents like CNP could be administered in conjunction with controlled exercise therapy to slow the OA disease progression and to repair damaged cartilage. The findings from this research provide the potential for developing novel agents to slow the pathophysiologic mechanisms and to treat OA in the young and old.
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Tasci A, Ferguson SJ, Büchler P. Numerical assessment on the effective mechanical stimuli for matrix-associated metabolism in chondrocyte-seeded constructs. J Tissue Eng Regen Med 2011; 5:210-9. [PMID: 20684030 DOI: 10.1002/term.307] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The self-regeneration capacity of articular cartilage is limited, due to its avascular and aneural nature. Loaded explants and cell cultures demonstrated that chondrocyte metabolism can be regulated via physiologic loading. However, the explicit ranges of mechanical stimuli that correspond to favourable metabolic response associated with extracellular matrix (ECM) synthesis are elusive.Unsystematic protocols lacking this knowledge produce inconsistent results. This study aims to determine the intrinsic ranges of physical stimuli that increase ECM synthesis and simultaneously inhibit nitric oxide (NO) production in chondrocyte–agarose constructs, by numerically reevaluating the experiments performed by Tsuang et al. (2008). Twelve loading patterns were simulated with poro-elastic finite element models in ABAQUS. Pressure on solid matrix, von Mises stress, maximum principle stress and pore pressure were selected as intrinsic mechanical stimuli.Their development rates and magnitudes at the steady state of cyclic loading were calculated with MATLAB at the construct level. Concurrent increase in glycosaminoglycan and collagen was observed at 2300 Pa pressure and 40 Pa/s pressure rate. Between 0–1500 Pa and 0–40 Pa/s, NO production was consistently positive with respect to controls, whereas ECM synthesis was negative in the same range. A linear correlation was found between pressure rate and NO production (R =0.77). Stress states identified in this study are generic and could be used to develop predictive algorithms for matrix production in agarose–chondrocyte constructs of arbitrary shape, size and agarose concentration. They could also be helpful to increase the efficacy of loading protocols for avascular tissue engineering.
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Affiliation(s)
- Arzu Tasci
- Institute for Surgical Technology and Biomechanics, University of Bern, Stauffacherstrasse 78, Bern, Switzerland.
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Xing Y, Gu Y, Gomes RR, You J. P2Y(2) receptors and GRK2 are involved in oscillatory fluid flow induced ERK1/2 responses in chondrocytes. J Orthop Res 2011; 29:828-33. [PMID: 21520257 PMCID: PMC3126889 DOI: 10.1002/jor.21319] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 10/28/2010] [Indexed: 02/04/2023]
Abstract
Mechanical loading is an important factor regulating cartilage metabolism maintained by chondrocytes. However, some of its underlying mechanisms remain poorly understood. In this study, we employed a chondrogenic cell line ATDC5 to investigate roles of P2Y(2) and GRK2 in chondrocyte mechanotransduction. We first confirmed the expression of chondrocyte markers in differentiated ATDC5 cells. We then exposed both differentiated and undifferentiated ATDC5 cells to oscillatory fluid flow, and found that differentiated ATDC5 cells responded to oscillatory fluid flow by increasing COX-2 and aggrecan expressions. More importantly, fluid flow induced ERK1/2 response in differentiated cells was increased more than 10 times compared to those in undifferentiated cells. Furthermore, we found that P2Y(2) mRNA and protein levels in differentiated ATDC5 cells were significantly higher than those in undifferentiated cells. In contrast, GRK2 protein levels in differentiated cells were significantly lower than those in undifferentiated cells. Finally, overexpressions of P2Y(2) and GRK2 in differentiated ATDC5 cells result in a 34% increase and a 21% decrease of the ERK1/2 phosphorylation, respectively, in response to oscillatory fluid flow, suggesting important roles of P2Y(2) and GRK2 in chondrocyte mechanotransduction.
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Affiliation(s)
| | | | | | - Jun You
- Corresponding Author: Jun You, Ph.D., Department of Orthopaedics, 500 University Drive, Hershey, PA 17033, U.S.A., , Tel: (01)-717-531-4819, Fax: (01)-717-531-7583
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Difference in Energy Metabolism of Annulus Fibrosus and Nucleus Pulposus Cells of the Intervertebral Disc. Cell Mol Bioeng 2011; 4:302-310. [PMID: 21625336 DOI: 10.1007/s12195-011-0164-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Low back pain is associated with intervertebral disc degeneration. One of the main signs of degeneration is the inability to maintain extracellular matrix integrity. Extracellular matrix synthesis is closely related to production of adenosine triphosphate (i.e. energy) of the cells. The intervertebral disc is composed of two major anatomical regions: annulus fibrosus and nucleus pulposus, which are structurally and compositionally different, indicating that their cellular metabolisms may also be distinct. The objective of this study was to investigate energy metabolism of annulus fibrosus and nucleus pulposus cells with and without dynamic compression, and examine differences between the two cell types. Porcine annulus and nucleus tissues were harvested and enzymatically digested. Cells were isolated and embedded into agarose constructs. Dynamically loaded samples were subjected to a sinusoidal displacement at 2 Hz and 15% strain for 4 h. Energy metabolism of cells was analyzed by measuring adenosine triphosphate content and release, glucose consumption, and lactate/nitric oxide production. A comparison of those measurements between annulus and nucleus cells was conducted. Annulus and nucleus cells exhibited different metabolic pathways. Nucleus cells had higher adenosine triphosphate content with and without dynamic loading, while annulus cells had higher lactate production and glucose consumption. Compression increased adenosine triphosphate release from both cell types and increased energy production of annulus cells. Dynamic loading affected energy metabolism of intervertebral disc cells, with the effect being greater in annulus cells.
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Rosenthal AK, Hempel D, Kurup IV, Masuda I, Ryan LM. Purine receptors modulate chondrocyte extracellular inorganic pyrophosphate production. Osteoarthritis Cartilage 2010; 18:1496-501. [PMID: 20709180 PMCID: PMC2975862 DOI: 10.1016/j.joca.2010.08.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 08/05/2010] [Accepted: 08/10/2010] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Extracellular inorganic pyrophosphate (ePPi) plays a key role in the regulation of normal and pathologic mineralization. The purpose of this work was to evaluate the role of P1 and P2 purine receptors in modulating ePPi production by articular chondrocytes. METHODS Porcine cartilage explants and chondrocyte monolayers were cultured in the presence of P1 agonists, or a P2 agonist or antagonist and inhibitors of P2 signaling. Ambient media ePPi concentrations were measured after 48-96h. RESULTS The P1 agonists NECA and CGS 21680 significantly decreased ePPi concentrations surrounding chondrocytes and cartilage explants. The P2 agonist, ADP, increased ePPi levels, and the P2 antagonist, suramin, decreased ePPi concentrations. Thapsigargin and 1,2 bis-(2-aminophenoxy)ethane-N,N,N'N'-tetra acetic acid (BAPTA), which dampen Ca(2+)-related P2 signaling, suppressed the response to ADP. CONCLUSIONS Purine receptors are important regulators of ePPi production by chondrocytes. P1 receptor stimulation diminishes and P2 receptor stimulation enhances ePPi production. Alterations in receptor signaling or aberrations of extracellular purine nucleotide metabolism resulting in abnormal quantities or proportions of P1 and P2 receptor ligands could foster changes in ePPi production that in turn affect mineralization. We propose a homeostatic role for extracellular purine nucleotides and purine receptors in stabilizing ePPi concentrations.
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Degala S, Zipfel WR, Bonassar LJ. Chondrocyte calcium signaling in response to fluid flow is regulated by matrix adhesion in 3-D alginate scaffolds. Arch Biochem Biophys 2010; 505:112-7. [PMID: 20705051 DOI: 10.1016/j.abb.2010.08.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 08/03/2010] [Accepted: 08/05/2010] [Indexed: 10/19/2022]
Abstract
The interaction between chondrocytes and their surrounding extracellular matrix plays an important role in regulating cartilage metabolism in response to environmental cues. This study characterized the role of cell adhesion on the calcium signaling response of chondrocytes to fluid flow. Bovine chondrocytes were suspended in alginate hydrogels functionalized with RGD at concentrations of 0-400μM. The hydrogels were perfused and the calcium signaling response of the cells was measured over a range of fluid velocities from 0 to 68μm/s. Attachment to RGD-alginate doubled the sensitivity of chondrocytes to flows in the range of 8-13μm/s, but at higher fluid velocities, the contribution of cell adhesion to the observed calcium signaling response was no longer apparent. The enhanced sensitivity to flow was dependent on the density of RGD-ligand present in the scaffolds. The RGD-enhanced sensitivity to flow was completely inhibited by the addition of soluble RGD which acted as a competitive inhibitor. The results of this study indicate a role for matrix adhesion in regulating chondrocyte response to fluid flow through a calcium dependent mechanism.
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Affiliation(s)
- Satish Degala
- Department of Biomedical Engineering, Cornell University, 151 Weill Hall, Ithaca, NY 14853, USA.
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Natoli RM, Skaalure S, Bijlani S, Chen KX, Hu J, Athanasiou KA. Intracellular Na(+) and Ca(2+) modulation increases the tensile properties of developing engineered articular cartilage. ACTA ACUST UNITED AC 2010; 62:1097-107. [PMID: 20131245 DOI: 10.1002/art.27313] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Significant collagen content and tensile properties are difficult to achieve in tissue-engineered articular cartilage. The aim of this study was to investigate whether treating developing tissue-engineered cartilage constructs with modulators of intracellular Na(+) or Ca(2+) could increase collagen concentration and construct tensile properties. METHODS Inhibitors of Na(+) ion transporters and stimulators of intracellular Ca(2+) were investigated for their ability to affect articular cartilage development in a scaffoldless, 3-dimensional chondrocyte culture. Using a systematic approach, we applied ouabain (Na(+)/K(+)-ATPase inhibitor), bumetanide (Na(+)/K(+)/2Cl(-) tritransporter inhibitor), histamine (cAMP activator), and ionomycin (a Ca(2+) ionophore) to tissue-engineered constructs for 1 hour daily on days 10-14 of culture and examined the constructs at 2 weeks or 4 weeks. The gross morphology, biochemical content, and compressive and tensile mechanical properties of the constructs were assayed. RESULTS The results of these experiments showed that 20 microM ouabain, 0.3 microM ionomycin, or their combination increased the tensile modulus by 40-95% compared with untreated controls and resulted in an increased amount of collagen normalized to construct wet weight. In constructs exposed to ouabain, the increased percentage of collagen per construct wet weight was secondary to decreased glycosaminoglycan production on a per-cell basis. Treatment with 20 microM ouabain also increased the ultimate tensile strength of neo-tissue by 56-86% at 4 weeks. Other construct properties, such as construct growth and type I collagen production, were affected differently by Na(+) modulation with ouabain versus Ca(2+) modulation with ionomycin. CONCLUSION These data are the first to show that treatments known to alter intracellular ion concentrations are a viable method for increasing the mechanical properties of engineered articular cartilage and identifying potentially important relationships to hydrostatic pressure mechanotransduction. Ouabain and ionomycin may be useful pharmacologic agents for increasing tensile integrity and directing construct maturation.
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Affiliation(s)
- Roman M Natoli
- Rice University, Houston, and Baylor College of Medicine, Houston, Texas, USA
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Garcia M, Knight MM. Cyclic loading opens hemichannels to release ATP as part of a chondrocyte mechanotransduction pathway. J Orthop Res 2010; 28:510-5. [PMID: 19890993 DOI: 10.1002/jor.21025] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The process of chondrocyte mechanotransduction is poorly understood. However, recent studies suggest the involvement of a purinergic calcium signaling pathway although the mechanism of ATP release has not been identified. The present study tests the hypothesis that cyclic compression opens hemichannels thereby triggering the release of ATP into the extracellular milieu activating P2 receptors. The well-established chondrocyte-agarose model was utilized enabling chondrocytes to be subjected to a 40-min period of cyclic compression at 0-15% strain and 1 Hz. The opening of hemichannels was determined using Lucifer yellow (LY) incorporation and fluorescence microscopy, whereas the release of ATP into the surrounding media was quantified using the luciferin-luciferase assay. Results indicated that cyclic compression activated hemichannels such that the percentage of cells showing LY incorporation increased from 50 to 70%. This was associated with a sevenfold increase in the release of ATP. Both LY incorporation and ATP release in response to mechanical loading were blocked by the hemichannel inhibitor, flufenamic acid. Treatment with apyrase or P2 receptor antagonists, suramin or oxidated-ATP, did not prevent the mechanically induced response. In conclusion, mechanical loading triggers release of ATP via hemichannels. Hence, this study provides the first evidence of hemichannel involvement in chondrocyte mechanobiology.
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Affiliation(s)
- Mariana Garcia
- Queen Mary University of London, School of Engineering and Materials Science, Mile End Road, London E1 4NS, United Kingdom
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Akanji OO, Sakthithasan P, Salter DM, Chowdhury TT. Dynamic compression alters NFkappaB activation and IkappaB-alpha expression in IL-1beta-stimulated chondrocyte/agarose constructs. Inflamm Res 2009; 59:41-52. [PMID: 19669392 DOI: 10.1007/s00011-009-0068-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 06/15/2009] [Accepted: 07/15/2009] [Indexed: 01/03/2023] Open
Abstract
OBJECTIVE AND DESIGN Determine the effect of IL-1beta and dynamic compression on NFkappaB activation and IkappaB-alpha gene expression in chondrocyte/agarose constructs. METHODS Constructs were cultured under free-swelling conditions or subjected to dynamic compression for up to 360 min with IL-1beta and/or PDTC (inhibits NFkappaB activation). Nuclear translocation of NFkappaB-p65 was analysed by immunofluoresence microscopy. Gene expression of IkappaB-alpha, iNOS, IL-1beta and IL-4 was assessed by real-time qPCR. RESULTS Nuclear translocation of NFkappaB-p65 was concomitant with an increase in nuclear fluorescence intensity which reached maximum values at 60 min with IL-1beta (p < 0.001). Dynamic compression or PDTC reduced nuclear fluorescence and NFkappaB nuclear translocation in cytokine-treated constructs (p < 0.001 and p < 0.01 respectively). IL-1beta increased IkappaB-alpha expression (p < 0.001) at 60 min and either induced iNOS (p < 0.001) and IL-1beta (p < 0.01) or inhibited IL-4 (p < 0.05) expression at 360 min. These time-dependent events were partially reversed by dynamic compression or PDTC (p < 0.01) with IL-1beta. Co-stimulation by dynamic compression and PDTC favoured suppression (IkappaB-alpha, iNOS, IL-1beta) or induction (IL-4) of gene expression. CONCLUSIONS NFkappaB is one of the key players in the mechanical and inflammatory pathways, and its inhibition by a biophysical/therapeutic approach could be a strategy for attenuating the catabolic response in osteoarthritis.
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Knight MM, McGlashan SR, Garcia M, Jensen CG, Poole CA. Articular chondrocytes express connexin 43 hemichannels and P2 receptors - a putative mechanoreceptor complex involving the primary cilium? J Anat 2009; 214:275-83. [PMID: 19207989 DOI: 10.1111/j.1469-7580.2008.01021.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mechanical loading is essential for the health and homeostasis of articular cartilage, although the fundamental mechanotransduction pathways are unclear. Previous studies have demonstrated that cyclic compression up-regulates proteoglycan synthesis via an intracellular Ca(2+) signalling pathway, mediated by the release of ATP. However, the mechanism(s) of ATP release has not been elucidated. The present study examines expression of the putative mechanosensitive ATP-release channel, connexin 43 and whether it is expressed on the chondrocyte primary cilium, which acts as a mechanosensor in a variety of other cell types. In addition the study characterized the expression of a range of purine receptors through which ATP may activate downstream signalling events controlling cell function. Bovine articular chondrocytes were isolated by sequential enzyme digestion and seeded in agarose constructs. To verify the presence of functional hemichannels, Lucifer yellow (LY) uptake into viable cells was quantified following treatment with a hemichannel agonist (EGTA) and antagonist (flufenamic acid). LY uptake was observed in 45% of chondrocytes, increasing to 83% following EGTA treatment (P < 0.001). Treatment with the hemichannel blocker, flufenamic acid, significantly decreased LY uptake to less than 5% with and without EGTA. Immunofluorescence and confocal microscopy confirmed the presence of primary cilia and the expression of connexin 43. Approximately 50% of bovine chondrocyte primary cilia were decorated with connexin 43. Human chondrocytes in situ within cartilage explants also expressed connexin 43 hemichannels. However, expression was confined to the upper 200 microm of the tissue closest to the articular surface. Immunofluorescence revealed the expression of a range of P2X and P2Y receptor subtypes within human articular cartilage. In conclusion, the expression of functional hemichannels by articular chondrocytes may represent the mechanism through which mechanical loading activates ATP release as part of a purinergic mechanotransduction pathway. Furthermore, the expression of connexin 43 on the chondrocyte primary cilium suggests the possible involvement of the cilium in this pathway.
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Pharmacological characterization of P2X1 and P2X3 purinergic receptors in bovine chondrocytes. Osteoarthritis Cartilage 2008; 16:1421-9. [PMID: 18448363 DOI: 10.1016/j.joca.2008.03.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Accepted: 03/24/2008] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The aim of the present study is that of characterizing, for the first time in a quantitative way, from a biochemical, physico chemical and functional point of view P2X(1) and P2X(3) purinergic receptors in bovine chondrocytes. The affinity and the potency of typical purinergic ligands were studied through competition binding experiments and their role in modulating chondrocyte actvities was investigated by analyzing nitric oxide (NO) and prostaglandin E2 (PGE(2)) release. METHODS Saturation, competition binding experiments, western blotting and immunohistochemistry assays on the P2X(1) and P2X(3) purinergic receptors in bovine chondrocytes were performed. Thermodynamic analysis of the P2X(1) and P2X(3) purinergic binding was studied to investigate the forces driving drug-receptor coupling. In the functional assays (NO and PGE(2) release) the potency of purinergic agonists and antagonists was evaluated. RESULTS Bovine chondrocytes expressed P2X(1) and P2X(3) purinergic receptors and thermodynamic parameters indicated that purinergic binding is enthalpy- and entropy-driven for agonists and totally entropy-driven for antagonists. Typical purinergic agonists such as adenosine 5'-triphosphate (ATP) and alpha,beta-methyleneATP were able to increase NO and PGE(2) release. A purinergic antagonist, A317491, was able to block the stimulatory effect on functional experiments mediated by the agonists. CONCLUSIONS These data demonstrate for the first time the presence of functional P2X(1) and P2X(3) purinergic receptors in bovine chondrocytes. Agonists and antagonists are thermodynamically discriminated and are able to modulate functional responses such as NO and PGE(2) release. These results suggest the potential role of novel purinergic antagonists in the treatment of pathophysiological diseases linked to the inflammation and involved in articular cartilage resorption.
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Oegema TR. Molecular basis of the interaction of inflammation and exercise: keep on walking! ARTHRITIS AND RHEUMATISM 2007; 56:3176-9. [PMID: 17907161 DOI: 10.1002/art.22934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
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