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Kajander K, Sirkiä SV, Vallittu PK, Heino TJ, Määttä JA. Bioactive glasses promote rapid pre-osteoblastic cell migration in contrast to hydroxyapatite, while carbonated apatite shows migration inhibiting properties. Sci Rep 2023; 13:20587. [PMID: 37996563 PMCID: PMC10667509 DOI: 10.1038/s41598-023-47883-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 11/20/2023] [Indexed: 11/25/2023] Open
Abstract
Different biomaterials have been clinically used as bone filling materials, although the mechanisms behind the biological effects are incompletely understood. To address this, we compared the effects of five different biomaterials: two bioactive glasses (45S5 and S53P4), hydroxyapatite (HAP), carbonated apatite (CAP), and alumina on the in vitro migration and viability of pre-osteoblastic cells. In addition, we studied the effects of biomaterials' calcium release on cell migration, viability and differentiation. We found differences between the materials as the bioactive glasses promoted rapid pre-osteoblastic cell migration. In contrast, CAP decreased cell migration, which was also associated with lower activity of migration related kinases. Bioactive glasses released significant amounts of calcium into the media, while CAP decreased the calcium concentration. The response of cells to calcium was mechanistically studied by blocking calcium sensing receptor (CaSR) and ATP-gated ion channel P2X7, but this had no effect on cell migration. Surprisingly, HAP and CAP initially decreased cell viability. In summary, bioactive glasses 45S5 and S53P4 had significant and long-lasting effects on the pre-osteoblastic cell migration, which could be related to the observed calcium dissolution. Additionally, bioactive glasses had no negative effects on cell viability, which was observed with HAP and CAP.
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Affiliation(s)
- Karoliina Kajander
- Institute of Biomedicine, Faculty of Medicine, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland.
| | - Saara V Sirkiä
- Department of Biomaterials Science and Turku Clinical Biomaterials Centre - TCBC, Institute of Dentistry, University of Turku, Lemminkäisenkatu 2, 20520, Turku, Finland
| | - Pekka K Vallittu
- Department of Biomaterials Science and Turku Clinical Biomaterials Centre - TCBC, Institute of Dentistry, University of Turku, Lemminkäisenkatu 2, 20520, Turku, Finland
- Wellbeing Services County of Southwest Finland, Turku, Finland
| | - Terhi J Heino
- Institute of Biomedicine, Faculty of Medicine, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland
| | - Jorma A Määttä
- Institute of Biomedicine, Faculty of Medicine, University of Turku, Kiinamyllynkatu 10, 20520, Turku, Finland.
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Mousavizadeh R, Waugh CM, DeBruin E, McCormack RG, Duronio V, Scott A. Exposure to oxLDL impairs TGF-β activity in human tendon cells. BMC Musculoskelet Disord 2023; 24:197. [PMID: 36927534 PMCID: PMC10018928 DOI: 10.1186/s12891-023-06308-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 03/10/2023] [Indexed: 03/18/2023] Open
Abstract
BACKGROUND Previous studies have shown that patients with hypercholesterolemia experience elevated levels of oxidized LDL (oxLDL), a molecule which triggers inflammation and collagenase activity. In this study we discovered novel mechanistic effects of oxLDL on tendon cells and the mediators regulating matrix remodeling by analyzing the expression and activity of related proteins and enzymes. These effects may contribute to tendon damage in patients with high cholesterol. METHODS Isolated human tendon cells (male and female donors age 28 ± 1.4 age 37 ± 5.7, respectively) were incubated in the presence or absence of oxLDL. The influence of oxLDL on the expression level of key mRNA and proteins was examined using real time quantitative PCR, ELISA and Western blots. The activities of enzymes relevant to collagen synthesis and breakdown (lysyl oxidase and matrix metalloproteinases) were quantified using fluorometry. Finally, the isolated human tendon cells in a 3D construct were exposed to combinations of oxLDL and TGF-β to examine their interacting effects on collagen matrix remodeling. RESULTS The one-way ANOVA of gene expression indicates that key mRNAs including TGFB, COL1A1, DCN, and LOX were significantly reduced in human tendon cells by oxLDL while MMPs were increased. The oxLDL reduced the activity of LOX at 50 µg/ml, whereas conversely MMP activities were induced at 25 µg/ml (P ≤ 0.01). COL1A1 synthesis and TGF-β secretion were also inhibited (P ≤ 0.05). Adding recombinant TGF-β reversed the effects of oxLDL on the expression of collagens and LOX. OxLDL also impaired collagen matrix remodeling (P ≤ 0.01), and adding TGF-β restored the native phenotype. CONCLUSION Exposure to oxLDL in patients with hypercholesterolemia may adversely affect the mechanical and structural properties of tendon tissue through a direct action of oxLDL on tendon cells, including impairment of TGF-β expression. This impairment leads to disturbed matrix remodeling and synthesis, thereby potentially leading to increased risk of acute or chronic tendon injury. Our discovery may provide an opportunity for developing effective treatments for tendon injury in hypercholesterolemia patients by targeting the TGF-β pathway.
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Affiliation(s)
- Rouhollah Mousavizadeh
- Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, Canada
| | - Charlie M Waugh
- Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, Canada
| | - Erin DeBruin
- Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, Canada
| | - Robert G McCormack
- Department of Orthopaedics, Faculty of Medicine, The University of British Columbia, Vancouver, BC, Canada
| | - Vincent Duronio
- Department of Medicine, Faculty of Medicine, The University of British Columbia, Vancouver, Canada
| | - Alex Scott
- Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, Canada.
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Scholp AJ, Jensen J, Chinnathambi S, Atluri K, Mendenhall A, Fowler T, Salem AK, Martin JA, Sander EA. Force-Bioreactor for Assessing Pharmacological Therapies for Mechanobiological Targets. Front Bioeng Biotechnol 2022; 10:907611. [PMID: 35928948 PMCID: PMC9343955 DOI: 10.3389/fbioe.2022.907611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 06/14/2022] [Indexed: 11/13/2022] Open
Abstract
Tissue fibrosis is a major health issue that impacts millions of people and is costly to treat. However, few effective anti-fibrotic treatments are available. Due to their central role in fibrotic tissue deposition, fibroblasts and myofibroblasts are the target of many therapeutic strategies centered primarily on either inducing apoptosis or blocking mechanical or biochemical stimulation that leads to excessive collagen production. Part of the development of these drugs for clinical use involves in vitro prescreening. 2D screens, however, are not ideal for discovering mechanobiologically significant compounds that impact functions like force generation and other cell activities related to tissue remodeling that are highly dependent on the conditions of the microenvironment. Thus, higher fidelity models are needed to better simulate in vivo conditions and relate drug activity to quantifiable functional outcomes. To provide guidance on effective drug dosing strategies for mechanoresponsive drugs, we describe a custom force-bioreactor that uses a fibroblast-seeded fibrin gels as a relatively simple mimic of the provisional matrix of a healing wound. As cells generate traction forces, the volume of the gel reduces, and a calibrated and embedded Nitinol wire deflects in proportion to the generated forces over the course of 6 days while overhead images of the gel are acquired hourly. This system is a useful in vitro tool for quantifying myofibroblast dose-dependent responses to candidate biomolecules, such as blebbistatin. Administration of 50 μM blebbistatin reliably reduced fibroblast force generation approximately 40% and lasted at least 40 h, which in turn resulted in qualitatively less collagen production as determined via fluorescent labeling of collagen.
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Affiliation(s)
- Austin J. Scholp
- Roy J. Carver Department of Biomedical Engineering, College of Engineering, University of Iowa, Iowa City, IA, United States
| | - Jordan Jensen
- Roy J. Carver Department of Biomedical Engineering, College of Engineering, University of Iowa, Iowa City, IA, United States
| | - Sathivel Chinnathambi
- Roy J. Carver Department of Biomedical Engineering, College of Engineering, University of Iowa, Iowa City, IA, United States
| | - Keerthi Atluri
- Division of Pharmaceutics and Translational Therapeutics, College of Pharmacy, University of Iowa, Iowa City, IA, United States
| | - Alyssa Mendenhall
- Roy J. Carver Department of Biomedical Engineering, College of Engineering, University of Iowa, Iowa City, IA, United States
| | - Timothy Fowler
- Department of Orthopedics and Rehabilitation, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Aliasger K. Salem
- Division of Pharmaceutics and Translational Therapeutics, College of Pharmacy, University of Iowa, Iowa City, IA, United States
| | - James A. Martin
- Department of Orthopedics and Rehabilitation, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Edward A. Sander
- Roy J. Carver Department of Biomedical Engineering, College of Engineering, University of Iowa, Iowa City, IA, United States
- Department of Orthopedics and Rehabilitation, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
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PYK2 mediates BzATP-induced extracellular matrix proteins synthesis. Biochem Biophys Res Commun 2017; 494:663-667. [PMID: 29061307 DOI: 10.1016/j.bbrc.2017.10.107] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 10/20/2017] [Indexed: 10/25/2022]
Abstract
Mechanical stimuli such as fluid shear and cyclic tension force induced extracellular adenosine triphosphate (ATP) release in osteoblasts. In particular, cyclic tension force-induced ATP enhances bone formation through P2X7 activation. Proline-rich tyrosine kinase 2 (PYK2) mediate osteoblasts differentiation is induced by mechanical stimuli. Furthermore, activation of PYK2 also was a response to integrin by mechanical stimuli. Extracellular matrix protein (ECMP)s, which are important factors for bone formation are expressed by osteoblasts. However, the effect of the interaction of 2'(3)-Ο-(4-Benzoylbenzoyl) adenosine-5'-triphosphate (BzATP), which is the agonist of the mechanosensitive receptor P2X7, with PYK2 on ECMP production is poorly understood. Thus, our purpose was to investigate the effects of PYK2 on BzATP-induced ECMP production in osteoblasts. BzATP increased phospho-PYK2 protein expression on days 3 and 7 of culture. Furthermore, the PYK2 inhibitor PF431394 inhibited the stimulatory effect of BzATP on the expression of type I collagen, bone sialoprotein and osteocalcin expression. PF431396 did not inhibit the stimulatory effect of BzATP on osteopontin (OPN) mRNA expression. These results suggest that mechanical stimuli activate P2X7 might induce ECMPs expression through PYK2 except in the case of OPN expression. Altogether, mechanical stimuli-induced ECMPs production might be implicated by extracellular ATP secretion or integrin via PYK2 activation.
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Cell Signaling in Tenocytes: Response to Load and Ligands in Health and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 920:79-95. [DOI: 10.1007/978-3-319-33943-6_7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Preclinical models for in vitro mechanical loading of bone-derived cells. BONEKEY REPORTS 2015; 4:728. [PMID: 26331007 DOI: 10.1038/bonekey.2015.97] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 05/29/2015] [Indexed: 02/06/2023]
Abstract
It is well established that bone responds to mechanical stimuli whereby physical forces are translated into chemical signals between cells, via mechanotransduction. It is difficult however to study the precise cellular and molecular responses using in vivo systems. In vitro loading models, which aim to replicate forces found within the bone microenvironment, make the underlying processes of mechanotransduction accessible to the researcher. Direct measurements in vivo and predictive modeling have been used to define these forces in normal physiological and pathological states. The types of mechanical stimuli present in the bone include vibration, fluid shear, substrate deformation and compressive loading, which can all be applied in vitro to monolayer and three-dimensional (3D) cultures. In monolayer, vibration can be readily applied to cultures via a low-magnitude, high-frequency loading rig. Fluid shear can be applied to cultures in multiwell plates via a simple rocking platform to engender gravitational fluid movement or via a pump to cells attached to a slide within a parallel-plate flow chamber, which may be micropatterned for use with osteocytes. Substrate strain can be applied via the vacuum-driven FlexCell system or via a four-point loading jig. 3D cultures better replicate the bone microenvironment and can also be subjected to the same forms of mechanical stimuli as monolayer, including vibration, fluid shear via perfusion flow, strain or compression. 3D cocultures that more closely replicate the bone microenvironment can be used to study the collective response of several cell types to loading. This technical review summarizes the methods for applying mechanical stimuli to bone cells in vitro.
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Lavagnino M, Wall ME, Little D, Banes AJ, Guilak F, Arnoczky SP. Tendon mechanobiology: Current knowledge and future research opportunities. J Orthop Res 2015; 33:813-22. [PMID: 25763779 PMCID: PMC4524513 DOI: 10.1002/jor.22871] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 02/13/2015] [Indexed: 02/04/2023]
Abstract
Tendons mainly function as load-bearing tissues in the muscloskeletal system; transmitting loads from muscle to bone. Tendons are dynamic structures that respond to the magnitude, direction, frequency, and duration of physiologic as well as pathologic mechanical loads via complex interactions between cellular pathways and the highly specialized extracellular matrix. This paper reviews the evolution and current knowledge of mechanobiology in tendon development, homeostasis, disease, and repair. In addition, we review several novel mechanotransduction pathways that have been identified recently in other tissues and cell types, providing potential research opportunities in the field of tendon mechanobiology. We also highlight current methods, models, and technologies being used in a wide variety of mechanobiology research that could be investigated in the context of their potential applicability for answering some of the fundamental unanswered questions in this field. The article concludes with a review of the major questions and future goals discussed during the recent ORS/ISMMS New Frontiers in Tendon Research Conference held on September 10 and 11, 2014 in New York City.
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Affiliation(s)
- Michael Lavagnino
- Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine Michigan State University, East Lansing, Michigan
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Manaka S, Tanabe N, Kariya T, Naito M, Takayama T, Nagao M, Liu D, Ito K, Maeno M, Suzuki N, Miyazaki M. Low-intensity pulsed ultrasound-induced ATP increases bone formation via the P2X7 receptor in osteoblast-like MC3T3-E1 cells. FEBS Lett 2014; 589:310-8. [PMID: 25542352 DOI: 10.1016/j.febslet.2014.12.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 12/03/2014] [Accepted: 12/09/2014] [Indexed: 10/24/2022]
Abstract
Low-intensity pulsed ultrasound (LIPUS) is used for bone healing in orthopedics and dentistry. It has been shown that LIPUS induces the secretion of extracellular adenosine triphosphate (ATP), a key mediator of osteoblast response to mechanical stimuli. However, the detailed mechanism of LIPUS-induced osteogenesis has been elusive. In this study, we investigated the role of the P2X7 receptor in LIPUS-induced osteogenesis. LIPUS induced the release of extracellular ATP, differentiation of osteoblasts and osteogenesis via the P2X7 receptor, without affecting the activity of alkaline phosphatase (ALPase). These results suggest that LIPUS-induced extracellular ATP promotes bone formation via the osteoblast P2X7 receptor independently of ALPase.
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Affiliation(s)
| | - Natsuko Tanabe
- Department of Biochemistry, Nihon University School of Dentistry, Tokyo, Japan; Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan.
| | - Taro Kariya
- Department of Orthodontics, Nihon University School of Dentistry, Tokyo, Japan
| | - Masako Naito
- Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan; Department of Anatomy, Nihon University School of Dentistry, Tokyo, Japan
| | - Tadahiro Takayama
- Department of Periodontology, Nihon University School of Dentistry, Tokyo, Japan; Division of Advanced Dental Treatment, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan
| | - Mayu Nagao
- Nihon University Graduate School of Dentistry, Tokyo, Japan
| | - Di Liu
- Department of Prosthodontics, School of Dentistry, Shandong University, Jinan, Shandong Province, China
| | | | - Masao Maeno
- Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan; Department of Oral Health Sciences, Nihon University School of Dentistry, Tokyo, Japan
| | - Naoto Suzuki
- Department of Biochemistry, Nihon University School of Dentistry, Tokyo, Japan; Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan
| | - Masashi Miyazaki
- Department of Periodontology, Nihon University School of Dentistry, Tokyo, Japan; Division of Advanced Dental Treatment, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan
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Vazquez M, Evans BAJ, Riccardi D, Evans SL, Ralphs JR, Dillingham CM, Mason DJ. A new method to investigate how mechanical loading of osteocytes controls osteoblasts. Front Endocrinol (Lausanne) 2014; 5:208. [PMID: 25538684 PMCID: PMC4260042 DOI: 10.3389/fendo.2014.00208] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 11/18/2014] [Indexed: 01/08/2023] Open
Abstract
Mechanical loading, a potent stimulator of bone formation, is governed by osteocyte regulation of osteoblasts. We developed a three-dimensional (3D) in vitro co-culture system to investigate the effect of loading on osteocyte-osteoblast interactions. MLO-Y4 cells were embedded in type I collagen gels and MC3T3-E1(14) or MG63 cells layered on top. Ethidium homodimer staining of 3D co-cultures showed 100% osteoblasts and 86% osteocytes were viable after 7 days. Microscopy revealed osteoblasts and osteocytes maintain their respective ovoid/pyriform and dendritic morphologies in 3D co-cultures. Reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR) of messenger ribonucleic acid (mRNA) extracted separately from osteoblasts and osteocytes, showed that podoplanin (E11), osteocalcin, and runt-related transcription factor 2 mRNAs were expressed in both cell types. Type I collagen (Col1a1) mRNA expression was higher in osteoblasts (P < 0.001), whereas, alkaline phosphatase mRNA was higher in osteocytes (P = 0.001). Immunohistochemistry revealed osteoblasts and osteocytes express E11, type I pro-collagen, and connexin 43 proteins. In preliminary experiments to assess osteogenic responses, co-cultures were treated with human recombinant bone morphogenetic protein 2 (BMP-2) or mechanical loading using a custom built loading device. BMP-2 treatment significantly increased osteoblast Col1a1 mRNA synthesis (P = 0.031) in MLO-Y4/MG63 co-cultures after 5 days treatment. A 16-well silicone plate, loaded (5 min, 10 Hz, 2.5 N) to induce 4000-4500 με cyclic compression within gels increased prostaglandin E2 (PGE2) release 0.5 h post-load in MLO-Y4 cells pre-cultured in 3D collagen gels for 48, 72 h, or 7 days. Mechanical loading of 3D co-cultures increased type I pro-collagen release 1 and 5 days later. These methods reveal a new osteocyte-osteoblast co-culture model that may be useful for investigating mechanically induced osteocyte control of osteoblast bone formation.
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Affiliation(s)
- Marisol Vazquez
- Arthritis Research UK Biomechanics and Bioengineering Centre, School of Biosciences, Cardiff University, Cardiff, UK
| | - Bronwen A. J. Evans
- Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff, UK
| | - Daniela Riccardi
- Division of Pathophysiology and Repair, School of Biosciences, Cardiff University, Cardiff, UK
| | - Sam L. Evans
- Institute of Mechanical and Manufacturing Engineering, School of Engineering, Cardiff University, Cardiff, UK
| | - Jim R. Ralphs
- Division of Pathophysiology and Repair, School of Biosciences, Cardiff University, Cardiff, UK
| | | | - Deborah J. Mason
- Division of Pathophysiology and Repair, School of Biosciences, Cardiff University, Cardiff, UK
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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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Receptor-independent effects of 2'(3')-O-(4-benzoylbenzoyl)ATP triethylammonium salt on cytosolic pH. Purinergic Signal 2013; 9:687-93. [PMID: 23689980 DOI: 10.1007/s11302-013-9365-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 04/23/2013] [Indexed: 10/26/2022] Open
Abstract
The effect of the relatively potent P2X7 receptor agonist 2'(3')-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate triethylammonium salt (BzATP-TEA) on cytosolic pH (pHi) was studied using MC3T3-E1 osteoblast-like cells, which endogenously express P2X7 receptors. pHi was measured fluorimetrically using the pH-sensitive dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein. BzATP-TEA (0.3-1.5 mM) elicited fast-onset alkalinization responses. In contrast, adenosine 5'-triphosphate disodium salt (5 mM) failed to reproduce the BzATP-TEA-induced responses, indicating a P2 receptor-independent mechanism. We speculated that triethylamine, which is present in solutions of BzATP-TEA, permeates the plasma membrane, and is protonated intracellularly, leading to an increase in pHi. Consistent with this hypothesis, triethylammonium (TEA) chloride mimicked the effects of BzATP-TEA on pHi. Moreover, measurements using a Cytosensor microphysiometer revealed that TEA chloride transiently suppressed proton efflux from cells, whereas washout of TEA transiently enhanced proton efflux. BzATP-TEA also elicited a sustained increase in proton efflux that was blocked specifically by the P2X7 antagonist A-438079. Taken together, we conclude that BzATP-TEA-induced alkalinization is unrelated to P2X7 activation, but is due to the presence of TEA. This effect may confound assessment of the outcomes of P2X7 activation by BzATP-TEA in other systems. Thus, control experiments using TEA chloride are recommended to distinguish between receptor-mediated and nonspecific effects of this widely used agonist. We performed such a control and confirmed that BzATP-TEA, but not TEA chloride, caused the elevation of cytosolic free Ca(2+) in MC3T3-E1 cells, ruling out the possibility that receptor-independent effects on pHi underlie BzATP-TEA-induced Ca(2+) signaling.
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Binderman I, Gadban N, Yaffe A. Cytoskeletal disease: a role in the etiology of adult periodontitis. Oral Dis 2013; 20:10-6. [DOI: 10.1111/odi.12128] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 04/29/2013] [Accepted: 04/29/2013] [Indexed: 12/01/2022]
Affiliation(s)
- I Binderman
- Department of Oral Biology; Sackler Faculty of Medicine; Maurice and Gabriela Goldschleger; School of Dental Medicine; Tel Aviv Israel
- Department of Bio-Medical Engineering; Faculty of Engineering; Tel Aviv University; Tel Aviv Israel
| | - N Gadban
- Department of Oral Biology; Sackler Faculty of Medicine; Maurice and Gabriela Goldschleger; School of Dental Medicine; Tel Aviv Israel
| | - A Yaffe
- Department of Prosthodontics; Haddasah Faculty of Dental Medicine; Hebrew University; Jerusalem Israel
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Qi J, Dmochowski JM, Banes AN, Tsuzaki M, Bynum D, Patterson M, Creighton A, Gomez S, Tech K, Cederlund A, Banes AJ. Differential expression and cellular localization of novel isoforms of the tendon biomarker tenomodulin. J Appl Physiol (1985) 2012; 113:861-71. [DOI: 10.1152/japplphysiol.00198.2012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Tenomodulin (Tnmd, also called Tendin) is classified as a type II transmembrane glycoprotein and is highly expressed in developing as well as in mature tendons. Along with scleraxis (scx), Tnmd is a candidate marker gene for tenocytes. Its function is unknown, but it has been reported to have anti-angiogenic properties. Results in a knockout mouse model did not substantiate that claim. It has homology to chondromodulin-I. Single nucleotide polymorphisms of TNMD have been associated with obesity, macular degeneration, and Alzheimer's disease in patients. In the present study, three Tnmd isoforms with deduced molecular weights of 20.3 (isoform II), 25.4 (isoform III), and 37.1 (isoform I) kDa were proposed and verified by Western blot from cells with green fluorescent protein-linked, overexpressed constructs, tissue, and by qPCR of isoforms from human tissues and cultured cells. Overexpression of each Tnmd isoform followed by immunofluorescence imaging showed that isoforms I and II had perinuclear localization while isoform III was cytoplasmic. Results of qPCR demonstrated differential expression of each Tnmd isoform in patient's specimens taken from flexor carpi radialis, biceps brachii, and flexor digitorum profundus tendons. Knockdown of Tnmd increased the expression of both scleraxis (scx) and myostatin, indicating a potential negative feedback loop between Tnmd and its regulators. Knockdown of all Tnmd isoforms simultaneously also reduced tenocyte proliferation. I-TASSER protein three-dimensional conformation modeling predictions indicated each Tnmd isoform had different structures and potential functions: isoform 1, modeled as a cytosine methyltransferase; isoform 2, a SUMO-1-like SENP-1 protease; and isoform 3, an α-syntrophin, plextrin homology domain scaffolding protein. Further functional studies with each Tnmd isoform may help us to better understand regulation of tenocyte proliferation, tendon development, response to injury and strain, as well as mechanisms in tendinoses. These results may indicate novel therapeutic targets in specific tenomodulin isoforms as well as treatments for tendon diseases.
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Affiliation(s)
- J. Qi
- University of North Carolina, Chapel Hill, North Carolina
- Flexcell International, Hillsborough, North Carolina
| | | | - A. N. Banes
- Flexcell International, Hillsborough, North Carolina
- North Carolina State University, Raleigh, North Carolina; and
| | - M. Tsuzaki
- Flexcell International, Hillsborough, North Carolina
| | - D. Bynum
- University of North Carolina, Chapel Hill, North Carolina
| | - M. Patterson
- University of North Carolina, Chapel Hill, North Carolina
| | - A. Creighton
- University of North Carolina, Chapel Hill, North Carolina
| | | | - K. Tech
- University of North Carolina, Chapel Hill, North Carolina
| | | | - A. J. Banes
- University of North Carolina, Chapel Hill, North Carolina
- Flexcell International, Hillsborough, North Carolina
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Grol MW, Zelner I, Dixon SJ. P2X₇-mediated calcium influx triggers a sustained, PI3K-dependent increase in metabolic acid production by osteoblast-like cells. Am J Physiol Endocrinol Metab 2012; 302:E561-75. [PMID: 22185840 DOI: 10.1152/ajpendo.00209.2011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The P2X₇ receptor is an ATP-gated cation channel expressed by a number of cell types, including osteoblasts. Genetically modified mice with loss of P2X₇ function exhibit altered bone formation. Moreover, activation of P2X₇ in vitro stimulates osteoblast differentiation and matrix mineralization, although the underlying mechanisms remain unclear. Because osteogenesis is associated with enhanced cellular metabolism, our goal was to characterize the effects of nucleotides on metabolic acid production (proton efflux) by osteoblasts. The P2X₇ agonist 2',3'-O-(4-benzoylbenzoyl)ATP (BzATP; 300 μM) induced dynamic membrane blebbing in MC3T3-E1 osteoblast-like cells (consistent with activation of P2X₇ receptors) but did not induce cell death. Using a Cytosensor microphysiometer, we found that 9-min exposure to BzATP (300 μM) caused a dramatic increase in proton efflux from MC3T3-E1 cells (∼2-fold), which was sustained for at least 1 h. In contrast, ATP or UTP (100 μM), which activate P2 receptors other than P2X₇, failed to elicit a sustained increase in proton efflux. Specific P2X₇ receptor antagonists A 438079 and A 740003 inhibited the sustained phase of the BzATP-induced response. Extracellular Ca²⁺ was required during P2X₇ receptor stimulation for initiation of sustained proton efflux, and removal of extracellular glucose within the sustained phase abolished the elevation elicited by BzATP. In addition, inhibition of phosphatidylinositol 3-kinase blocked the maintenance but not initiation of the sustained phase. Taken together, we conclude that brief activation of P2X₇ receptors on osteoblast-like cells triggers a dramatic, Ca²⁺-dependent stimulation of metabolic acid production. This increase in proton efflux is sustained and dependent on glucose and phosphatidylinositol 3-kinase activity.
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Affiliation(s)
- Matthew W Grol
- Dept. of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, Univ. of Western Ontario, London, ON, Canada
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Chicatun F, Pedraza CE, Ghezzi CE, Marelli B, Kaartinen MT, McKee MD, Nazhat SN. Osteoid-mimicking dense collagen/chitosan hybrid gels. Biomacromolecules 2011; 12:2946-56. [PMID: 21661759 DOI: 10.1021/bm200528z] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Bone extracellular matrix (ECM) is a 3D network, composed of collagen type I and a number of other macromolecules, including glycosaminoglycans (GAGs), which stimulate signaling pathways that regulate osteoblast growth and differentiation. To model the ECM of bone for tissue regenerative approaches, dense collagen/chitosan (Coll/CTS) hybrid hydrogels were developed using different proportions of CTS to mimic GAG components of the ECM. MC3T3-E1 mouse calvaria preosteoblasts were seeded within plastically compressed Coll/CTS hydrogels with solid content approaching that of native bone osteoid. Dense, cellular Coll/CTS hybrids were maintained for up to 8 weeks under either basal or osteogenic conditions. Higher CTS content significantly increased gel resistance to collagenase degradation. The incorporation of CTS to collagen gels decreased the apparent tensile modulus from 1.82 to 0.33 MPa. In contrast, the compressive modulus of Coll/CTS hybrids increased in direct proportion to CTS content exhibiting an increase from 23.50 to 55.25 kPa. CTS incorporation also led to an increase in scaffold resistance to cell-induced contraction. MC3T3-E1 viability, proliferation, and matrix remodeling capability (via matrix metalloproteinase expression) were maintained. Alkaline phosphatase activity was increased up to two-fold, and quantification of phosphate mineral deposition was significantly increased with CTS incorporation. Thus, dense Coll/CTS scaffolds provide osteoid-like models for the study of osteoblast differentiation and bone tissue engineering.
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Affiliation(s)
- Florencia Chicatun
- Department of Mining and Materials Engineering, Faculty of Engineering, McGill University, Montreal, Quebec, Canada H3A 2B2
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Genetos DC, Karin NJ, Geist DJ, Donahue HJ, Duncan RL. Purinergic signaling is required for fluid shear stress-induced NF-κB translocation in osteoblasts. Exp Cell Res 2011; 317:737-44. [PMID: 21237152 PMCID: PMC3049820 DOI: 10.1016/j.yexcr.2011.01.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 01/03/2011] [Accepted: 01/04/2011] [Indexed: 11/19/2022]
Abstract
Fluid shear stress regulates gene expression in osteoblasts, in part by activation of the transcription factor NF-κB. We examined whether this process was under the control of purinoceptor activation. MC3T3-E1 osteoblasts under static conditions expressed the NF-κB inhibitory protein IκBα and exhibited cytosolic localization of NF-κB. Under fluid shear stress, IκBα levels decreased, and concomitant nuclear localization of NF-κB was observed. Cells exposed to fluid shear stress in ATP-depleted medium exhibited no significant reduction in IκBα, and NF-κB remained within the cytosol. Similar results were found using oxidized ATP or Brilliant Blue G, P2X(7) receptor antagonists, indicating that the P2X(7) receptor is responsible for fluid shear-stress-induced IκBα degradation and nuclear accumulation of NF-κB. Pharmacologic blockage of the P2Y6 receptor also prevented shear-induced IκBα degradation. These phenomena involved neither ERK1/2 signaling nor autocrine activation by P2X(7)-generated lysophosphatidic acid. Our results suggest that fluid shear stress regulates NF-κB activity through the P2Y(6) and P2X(7) receptor.
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Affiliation(s)
- Damian C Genetos
- Department of Anatomy, Cell Biology, and Physiology, School of Veterinary Medicine, University of California, Davis, CA, USA.
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Sumanasinghe RD, Osborne JA, Loboa EG. Mesenchymal stem cell-seeded collagen matrices for bone repair: effects of cyclic tensile strain, cell density, and media conditions on matrix contraction in vitro. J Biomed Mater Res A 2009; 88:778-86. [PMID: 18357565 DOI: 10.1002/jbm.a.31913] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Type I collagen is the most abundant extracellular matrix protein in bone and contains arginine- glycine-aspartic acid sequences that promote cell adhesion and proliferation. We have previously shown that human mesenchymal stem cells (hMSCs) seeded in three-dimensional (3D) collagen gels upregulate BMP-2 mRNA expression in response to tensile strain, indicative of osteogenesis. Therefore, collagen could be a promising scaffold material for functional bone tissue engineering using hMSCs. However, high contraction of the collagen gels by hMSCs poses a challenge to creating large, tissue-engineered bone constructs. The effects of cyclic tensile strain, medium (with and without dexamethasone), and hMSC seeding density on contraction of collagen matrices have not been investigated. hMSCs were seeded in 3D collagen gels and subjected to cyclic tensile strain of 10% or 12% for 4 h/day at a frequency of 1 Hz in osteogenic-differentiating or complete MSC growth media for up to 14 days. Viability of hMSCs was not affected by strain or media conditions. While initial seeding density affected matrix contraction alone, there was a high interdependence of strain and medium on matrix contraction. These findings suggest a correlation between hMSC proliferation and osteogenic differentiation on collagen matrix contraction that is affected by media, cell-seeding density, and cyclic tensile strain. It is vital to understand the effects of culture conditions on collagen matrix contraction by hMSCs in order to consider hMSC-seeded collagen constructs for functional bone tissue engineering in vitro.
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Affiliation(s)
- Ruwan D Sumanasinghe
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Raleigh, North Carolina
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Pfeiler TW, Sumanasinghe RD, Loboa EG. Finite element modeling of 3D human mesenchymal stem cell-seeded collagen matrices exposed to tensile strain. J Biomech 2008; 41:2289-96. [PMID: 18539285 DOI: 10.1016/j.jbiomech.2008.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 03/01/2008] [Accepted: 04/04/2008] [Indexed: 11/18/2022]
Abstract
The use of human mesenchymal stem cells (hMSCs) in tissue engineering is attractive due to their ability to extensively self-replicate and differentiate into a multitude of cell lineages. It has been experimentally established that hMSCs are influenced by chemical and mechanical signals. However, the combined chemical and mechanical in vitro culture conditions that lead to functional tissue require greater understanding. In this study, finite element models were created to evaluate the local loading conditions on bone marrow-derived hMSCs seeded in three-dimensional collagen matrices exposed to cyclic tensile strain. Mechanical property and geometry data used in the models were obtained experimentally from a previous study in our laboratory and from mechanical testing. Eight finite element models were created to simulate three-dimensional hMSC-seeded collagen matrices exposed to different levels of cyclic tensile strain (10% and 12%), culture media (complete growth and osteogenic differentiating), and durations of culture (7 and 14 days). Through finite element analysis, it was determined that globally applied uniaxial tensile strains of 10% and 12% resulted in local strains up to 18.3% and 21.8%, respectively. Model results were also compared to experimental studies in an attempt to explain observed differences between hMSC response to 10% and 12% cyclic tensile strain.
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Affiliation(s)
- T Wayne Pfeiler
- 2142 Burlington Laboratories, Joint Department of Biomedical Engineering at NC State University and UNC-Chapel Hill, Campus Box 7115, Raleigh, NC 27695-7115, USA
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