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Wilmoth RL, Sharma S, Ferguson VL, Bryant SJ. The effects of prostaglandin E2 on gene expression of IDG-SW3-derived osteocytes in 2D and 3D culture. Biochem Biophys Res Commun 2022; 630:8-15. [PMID: 36126467 DOI: 10.1016/j.bbrc.2022.09.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 09/02/2022] [Indexed: 11/20/2022]
Abstract
Prostaglandin E2 (PGE2) is a key signaling molecule produced by osteocytes in response to mechanical loading, but its effect on osteocytes is less understood. This work examined the effect of PGE2 on IDG-SW3-derived osteocytes in standard 2D culture (collagen-coated tissue culture polystyrene) and in a 3D degradable poly(ethylene glycol) hydrogel. IDG-SW3 cells were differentiated for 35 days into osteocytes in 2D and 3D cultures. 3D culture led to a more mature osteocyte phenotype with 100-fold higher Sost expression. IDG-SW3-derived osteocytes were treated with PGE2 and assessed for expression of genes involved in PGE2, anabolic, and catabolic signaling. In 2D, PGE2 had a rapid (1 h) and sustained (24 h) effect on many PGE2 signaling genes, a rapid stimulatory effect on Il6, and a sustained inhibitory effect on Tnfrsf11b and Bglap. Comparing culture environment without PGE2, osteocytes had higher expression of all four EP receptors and Sost but lower expression of Tnfrsf11b, Bglap, and Gja1 in 3D. Osteocytes were more responsive to PGE2 in 3D. With increasing PGE2, 3D led to increased Gja1 and decreased Sost expressions and a higher Tnfrsf11b/Tnfsf11 ratio, indicating an anabolic response. Further analysis in 3D revealed that EP4, the receptor implicated in PGE2 signaling in bone, was not responsible for the PGE2-induced gene expression changes in osteocytes. In summary, osteocytes are highly responsive to PGE2 when cultured in an in vitro 3D hydrogel model suggesting that autocrine and paracrine PGE2 signaling in osteocytes may play a role in bone homeostasis.
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Affiliation(s)
- Rachel L Wilmoth
- Mechanical Engineering, University of Colorado, 1111 Engineering Dr, Boulder, CO, 80309, USA
| | - Sadhana Sharma
- Chemical and Biological Engineering, University of Colorado, 3415 Colorado Ave, Boulder, CO, 80309, USA
| | - Virginia L Ferguson
- Mechanical Engineering, University of Colorado, 1111 Engineering Dr, Boulder, CO, 80309, USA; BioFrontiers Institute, University of Colorado, 3415 Colorado Ave, Boulder, CO, 80309, USA; Materials Science and Engineering, University of Colorado, 4001 Discovery Dr., Boulder, CO, 80309, USA
| | - Stephanie J Bryant
- Chemical and Biological Engineering, University of Colorado, 3415 Colorado Ave, Boulder, CO, 80309, USA; BioFrontiers Institute, University of Colorado, 3415 Colorado Ave, Boulder, CO, 80309, USA; Materials Science and Engineering, University of Colorado, 4001 Discovery Dr., Boulder, CO, 80309, USA.
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2
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Choi JUA, Kijas AW, Lauko J, Rowan AE. The Mechanosensory Role of Osteocytes and Implications for Bone Health and Disease States. Front Cell Dev Biol 2022; 9:770143. [PMID: 35265628 PMCID: PMC8900535 DOI: 10.3389/fcell.2021.770143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 12/13/2021] [Indexed: 12/14/2022] Open
Abstract
Bone homeostasis is a dynamic equilibrium between bone-forming osteoblasts and bone-resorbing osteoclasts. This process is primarily controlled by the most abundant and mechanosensitive bone cells, osteocytes, that reside individually, within chambers of porous hydroxyapatite bone matrix. Recent studies have unveiled additional functional roles for osteocytes in directly contributing to local matrix regulation as well as systemic roles through endocrine functions by communicating with distant organs such as the kidney. Osteocyte function is governed largely by both biochemical signaling and the mechanical stimuli exerted on bone. Mechanical stimulation is required to maintain bone health whilst aging and reduced level of loading are known to result in bone loss. To date, both in vivo and in vitro approaches have been established to answer important questions such as the effect of mechanical stimuli, the mechanosensors involved, and the mechanosensitive signaling pathways in osteocytes. However, our understanding of osteocyte mechanotransduction has been limited due to the technical challenges of working with these cells since they are individually embedded within the hard hydroxyapatite bone matrix. This review highlights the current knowledge of the osteocyte functional role in maintaining bone health and the key regulatory pathways of these mechanosensitive cells. Finally, we elaborate on the current therapeutic opportunities offered by existing treatments and the potential for targeting osteocyte-directed signaling.
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Affiliation(s)
- Jung Un Ally Choi
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, Australia
| | - Amanda W Kijas
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, Australia
| | - Jan Lauko
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, Australia
| | - Alan E Rowan
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, Australia
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3
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Effects of Extracellular Osteoanabolic Agents on the Endogenous Response of Osteoblastic Cells. Cells 2021; 10:cells10092383. [PMID: 34572032 PMCID: PMC8471159 DOI: 10.3390/cells10092383] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/31/2021] [Accepted: 09/07/2021] [Indexed: 12/27/2022] Open
Abstract
The complex multidimensional skeletal organization can adapt its structure in accordance with external contexts, demonstrating excellent self-renewal capacity. Thus, optimal extracellular environmental properties are critical for bone regeneration and inextricably linked to the mechanical and biological states of bone. It is interesting to note that the microstructure of bone depends not only on genetic determinants (which control the bone remodeling loop through autocrine and paracrine signals) but also, more importantly, on the continuous response of cells to external mechanical cues. In particular, bone cells sense mechanical signals such as shear, tensile, loading and vibration, and once activated, they react by regulating bone anabolism. Although several specific surrounding conditions needed for osteoblast cells to specifically augment bone formation have been empirically discovered, most of the underlying biomechanical cellular processes underneath remain largely unknown. Nevertheless, exogenous stimuli of endogenous osteogenesis can be applied to promote the mineral apposition rate, bone formation, bone mass and bone strength, as well as expediting fracture repair and bone regeneration. The following review summarizes the latest studies related to the proliferation and differentiation of osteoblastic cells, enhanced by mechanical forces or supplemental signaling factors (such as trace metals, nutraceuticals, vitamins and exosomes), providing a thorough overview of the exogenous osteogenic agents which can be exploited to modulate and influence the mechanically induced anabolism of bone. Furthermore, this review aims to discuss the emerging role of extracellular stimuli in skeletal metabolism as well as their potential roles and provide new perspectives for the treatment of bone disorders.
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4
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Hemmatian H, Bakker AD, Klein-Nulend J, van Lenthe GH. Alterations in osteocyte lacunar morphology affect local bone tissue strains. J Mech Behav Biomed Mater 2021; 123:104730. [PMID: 34438250 DOI: 10.1016/j.jmbbm.2021.104730] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 06/16/2021] [Accepted: 07/17/2021] [Indexed: 11/17/2022]
Abstract
Osteocytes are capable of remodeling their perilacunar bone matrix, which causes considerable variations in the shape and size of their lacunae. If these variations in lacunar morphology cause changes in the mechanical environment of the osteocytes, in particular local strains, they would subsequently affect bone mechanotransduction, since osteocytes are likely able to directly sense these strains. The purpose of this study is to quantify the effect of alterations in osteocyte lacunar morphology on peri-lacunar bone tissue strains. To this end, we related the actual lacunar shape in fibulae of six young-adult (5-month) and six old (23-month) mice, quantified by high-resolution micro-computed tomography, to microscopic strains, analyzed by micro-finite element modeling. We showed that peak effective strain increased by 12.6% in osteocyte cell bodies (OCYs), 9.6% in pericellular matrix (PCM), and 5.3% in extra cellular matrix (ECM) as the lacunae volume increased from 100-200 μm3 to 500-600 μm3. Lacunae with a larger deviation (>8°) in orientation from the longitudinal axis of the bone are exposed to 8% higher strains in OCYs, 6.5% in PCM, 4.2% in ECM than lacunae with a deviation in orientation below 8°. Moreover, increased lacuna sphericity from 0 to 0.5 to 0.7-1 led to 25%, 23%, and 13% decrease in maximum effective strains in OCYs, PCM, and ECM, respectively. We further showed that due to the presence of smaller and more round lacunae in old mice, local bone tissue strains are on average 5% lower in the vicinity of lacunae and their osteocytes of old mice compared to young. Understanding how changes in lacunar morphology affect the micromechanical environment of osteocytes presents a first step in unraveling their potential role in impaired bone mechanoresponsiveness with e.g. aging.
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Affiliation(s)
- Haniyeh Hemmatian
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium; Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands; Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Astrid D Bakker
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands
| | - Jenneke Klein-Nulend
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands
| | - G Harry van Lenthe
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium.
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5
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Gould NR, Torre OM, Leser JM, Stains JP. The cytoskeleton and connected elements in bone cell mechano-transduction. Bone 2021; 149:115971. [PMID: 33892173 PMCID: PMC8217329 DOI: 10.1016/j.bone.2021.115971] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/30/2021] [Accepted: 04/17/2021] [Indexed: 02/07/2023]
Abstract
Bone is a mechano-responsive tissue that adapts to changes in its mechanical environment. Increases in strain lead to increased bone mass acquisition, whereas decreases in strain lead to a loss of bone mass. Given that mechanical stress is a regulator of bone mass and quality, it is important to understand how bone cells sense and transduce these mechanical cues into biological changes to identify druggable targets that can be exploited to restore bone cell mechano-sensitivity or to mimic mechanical load. Many studies have identified individual cytoskeletal components - microtubules, actin, and intermediate filaments - as mechano-sensors in bone. However, given the high interconnectedness and interaction between individual cytoskeletal components, and that they can assemble into multiple discreet cellular structures, it is likely that the cytoskeleton as a whole, rather than one specific component, is necessary for proper bone cell mechano-transduction. This review will examine the role of each cytoskeletal element in bone cell mechano-transduction and will present a unified view of how these elements interact and work together to create a mechano-sensor that is necessary to control bone formation following mechanical stress.
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Affiliation(s)
- Nicole R Gould
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Olivia M Torre
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Jenna M Leser
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, USA..
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Gardinier JD. The Diminishing Returns of Mechanical Loading and Potential Mechanisms that Desensitize Osteocytes. Curr Osteoporos Rep 2021; 19:436-443. [PMID: 34216359 PMCID: PMC9306018 DOI: 10.1007/s11914-021-00693-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/27/2021] [Indexed: 11/30/2022]
Abstract
Adaptation to mechanical loading is critical to maintaining bone mass and offers therapeutic potential to preventing age-related bone loss and osteoporosis. However, increasing the duration of loading is met with "diminishing returns" as the anabolic response quickly becomes saturated. As a result, the anabolic response to daily activities and repetitive bouts of loading is limited by the underlying mechanisms that desensitize and render bone unresponsive at the cellular level. Osteocytes are the primary cells that respond to skeletal loading and facilitate the overall anabolic response. Although many of osteocytes' signaling mechanisms activated in response to loading are considered anabolic in nature, several of them can also render osteocytes insensitive to further stimuli and thereby creating a negative feedback loop that limits osteocytes' overall response. The purpose of this review is to examine the potential mechanisms that may contribute to the loss of mechanosensitivity. In particular, we examined the inactivation/desensitization of ion channels and signaling molecules along with the potential role of endocytosis and cytoskeletal reorganization. The significance in defining the negative feedback loop is the potential to identify unique targets for enabling osteocytes to maintain their sensitivity. In doing so, we can begin to cultivate new strategies that capitalize on the anabolic nature of daily activities that repeatedly load the skeleton.
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Jin J, Seddiqi H, Bakker AD, Wu G, Verstappen JFM, Haroon M, Korfage JAM, Zandieh‐Doulabi B, Werner A, Klein‐Nulend J, Jaspers RT. Pulsating fluid flow affects pre-osteoblast behavior and osteogenic differentiation through production of soluble factors. Physiol Rep 2021; 9:e14917. [PMID: 34174021 PMCID: PMC8234477 DOI: 10.14814/phy2.14917] [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: 05/12/2021] [Accepted: 05/13/2021] [Indexed: 11/24/2022] Open
Abstract
Bone mass increases after error-loading, even in the absence of osteocytes. Loaded osteoblasts may produce a combination of growth factors affecting adjacent osteoblast differentiation. We hypothesized that osteoblasts respond to a single load in the short-term (minutes) by changing F-actin stress fiber distribution, in the intermediate-term (hours) by signaling molecule production, and in the long-term (days) by differentiation. Furthermore, growth factors produced during and after mechanical loading by pulsating fluid flow (PFF) will affect osteogenic differentiation. MC3T3-E1 pre-osteoblasts were either/not stimulated by 60 min PFF (amplitude, 1.0 Pa; frequency, 1 Hz; peak shear stress rate, 6.5 Pa/s) followed by 0-6 h, or 21/28 days of post-incubation without PFF. Computational analysis revealed that PFF immediately changed distribution and magnitude of fluid dynamics over an adherent pre-osteoblast inside a parallel-plate flow chamber (immediate impact). Within 60 min, PFF increased nitric oxide production (5.3-fold), altered actin distribution, but did not affect cell pseudopodia length and cell orientation (initial downstream impact). PFF transiently stimulated Fgf2, Runx2, Ocn, Dmp1, and Col1⍺1 gene expression between 0 and 6 h after PFF cessation. PFF did not affect alkaline phosphatase nor collagen production after 21 days, but altered mineralization after 28 days. In conclusion, a single bout of PFF with indirect associated release of biochemical factors, stimulates osteoblast differentiation in the long-term, which may explain enhanced bone formation resulting from mechanical stimuli.
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Affiliation(s)
- Jianfeng Jin
- Department of Oral Cell BiologyAcademic Centre for Dentistry Amsterdam (ACTA)University of Amsterdam and Vrije Universiteit AmsterdamAmsterdam Movement SciencesAmsterdamThe Netherlands
| | - Hadi Seddiqi
- Department of Oral Cell BiologyAcademic Centre for Dentistry Amsterdam (ACTA)University of Amsterdam and Vrije Universiteit AmsterdamAmsterdam Movement SciencesAmsterdamThe Netherlands
| | - Astrid D. Bakker
- Department of Oral Cell BiologyAcademic Centre for Dentistry Amsterdam (ACTA)University of Amsterdam and Vrije Universiteit AmsterdamAmsterdam Movement SciencesAmsterdamThe Netherlands
| | - Gang Wu
- Department of Oral Implantology and Prosthetic DentistryAcademic Centre for Dentistry Amsterdam (ACTA)University of Amsterdam and Vrije Universiteit AmsterdamAmsterdam Movement SciencesAmsterdamThe Netherlands
| | - Johanna F. M. Verstappen
- Division of Molecular Intensive Care MedicineDepartment of Anesthesiology and Intensive Care MedicineUniversity Hospital TuebingenTübingenGermany
| | - Mohammad Haroon
- Laboratory for MyologyFaculty of Behavioral and Movement SciencesVrije Universiteit AmsterdamAmsterdam Movement SciencesAmsterdamThe Netherlands
| | - Joannes A. M. Korfage
- Department of Functional AnatomyAcademic Centre for Dentistry Amsterdam (ACTA)University of Amsterdam and Vrije Universiteit AmsterdamAmsterdam Movement SciencesAmsterdamThe Netherlands
| | - Behrouz Zandieh‐Doulabi
- Department of Oral Cell BiologyAcademic Centre for Dentistry Amsterdam (ACTA)University of Amsterdam and Vrije Universiteit AmsterdamAmsterdam Movement SciencesAmsterdamThe Netherlands
| | - Arie Werner
- Department of Dental Materials ScienceAcademic Centre for Dentistry Amsterdam (ACTA)University of Amsterdam and Vrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Jenneke Klein‐Nulend
- Department of Oral Cell BiologyAcademic Centre for Dentistry Amsterdam (ACTA)University of Amsterdam and Vrije Universiteit AmsterdamAmsterdam Movement SciencesAmsterdamThe Netherlands
| | - Richard T. Jaspers
- Laboratory for MyologyFaculty of Behavioral and Movement SciencesVrije Universiteit AmsterdamAmsterdam Movement SciencesAmsterdamThe Netherlands
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8
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Patil KC, Soekmadji C. Extracellular Vesicle-Mediated Bone Remodeling and Bone Metastasis: Implications in Prostate Cancer. Subcell Biochem 2021; 97:297-361. [PMID: 33779922 DOI: 10.1007/978-3-030-67171-6_12] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Bone metastasis is the tendency of certain primary tumors to spawn and dictate secondary neoplasia in the bone. The process of bone metastasis is regulated by the dynamic crosstalk between metastatic cancer cells, cellular components of the bone marrow microenvironment (osteoblasts, osteoclasts, and osteocytes), and the bone matrix. The feed-forward loop mechanisms governs the co-option of homeostatic bone remodeling by cancer cells in bone. Recent developments have highlighted the discovery of extracellular vesicles (EVs) and their diverse roles in distant outgrowths. Several studies have implicated EV-mediated interactions between cancer cells and the bone microenvironment in synergistically promoting pathological skeletal metabolism in the metastatic site. Nevertheless, the potential role that EVs serve in arbitrating intricate sequences of coordinated events within the bone microenvironment remains an emerging field. In this chapter, we review the role of cellular participants and molecular mechanisms in regulating normal bone physiology and explore the progress of current research into bone-derived EVs in directly triggering and coordinating the processes of physiological bone remodeling. In view of the emerging role of EVs in interorgan crosstalk, this review also highlights the multiple systemic pathophysiological processes orchestrated by the EVs to direct organotropism in bone in prostate cancer. Given the deleterious consequences of bone metastasis and its clinical importance, in-depth knowledge of the multifarious role of EVs in distant organ metastasis is expected to open new possibilities for prognostic evaluation and therapeutic intervention for advanced bone metastatic prostate cancer.
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Affiliation(s)
- Kalyani C Patil
- Translational Research Institute, Academic Health System, Hamad Medical Corporation, Doha, Qatar
| | - Carolina Soekmadji
- Department of Cell and Molecular Biology, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia. .,School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, QLD, Australia.
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Hua R, Zhang J, Riquelme MA, Jiang JX. Connexin Gap Junctions and Hemichannels Link Oxidative Stress to Skeletal Physiology and Pathology. Curr Osteoporos Rep 2021; 19:66-74. [PMID: 33403446 PMCID: PMC8174533 DOI: 10.1007/s11914-020-00645-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/16/2020] [Indexed: 12/15/2022]
Abstract
PURPOSE OF REVIEW The goal of this review is to provide an overview of the impact and underlying mechanism of oxidative stress on connexin channel function, and their roles in skeletal aging, estrogen deficiency, and glucocorticoid excess associated bone loss. RECENT FINDINGS Connexin hemichannel opening is increased under oxidative stress conditions, which confers a cell protective role against oxidative stress-induced cell death. Oxidative stress acts as a key contributor to aging, estrogen deficiency, and glucocorticoid excess-induced osteoporosis and impairs osteocytic network and connexin gap junction communication. This paper reviews the current knowledge for the role of oxidative stress and connexin channels in the pathogenesis of osteoporosis and physiological and pathological responses of connexin channels to oxidative stress. Oxidative stress decreases osteocyte viability and impairs the balance of anabolic and catabolic responses. Connexin 43 (Cx43) channels play a critical role in bone remodeling, mechanotransduction, and survival of osteocytes. Under oxidative stress conditions, there is a consistent reduction of Cx43 expression, while the opening of Cx43 hemichannels protects osteocytes against cell injury caused by oxidative stress.
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Affiliation(s)
- Rui Hua
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Jingruo Zhang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA.
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10
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Abstract
Osteocytes are an ancient cell, appearing in fossilized skeletal remains of early fish and dinosaurs. Despite its relative high abundance, even in the context of nonskeletal cells, the osteocyte is perhaps among the least studied cells in all of vertebrate biology. Osteocytes are cells embedded in bone, able to modify their surrounding extracellular matrix via specialized molecular remodeling mechanisms that are independent of the bone forming osteoblasts and bone-resorbing osteoclasts. Osteocytes communicate with osteoclasts and osteoblasts via distinct signaling molecules that include the RankL/OPG axis and the Sost/Dkk1/Wnt axis, among others. Osteocytes also extend their influence beyond the local bone environment by functioning as an endocrine cell that controls phosphate reabsorption in the kidney, insulin secretion in the pancreas, and skeletal muscle function. These cells are also finely tuned sensors of mechanical stimulation to coordinate with effector cells to adjust bone mass, size, and shape to conform to mechanical demands.
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Affiliation(s)
- Alexander G Robling
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA;
| | - Lynda F Bonewald
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA;
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11
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Amaroli A, Sabbieti MG, Marchetti L, Zekiy AO, Utyuzh AS, Marchegiani A, Laus F, Cuteri V, Benedicenti S, Agas D. The effects of 808-nm near-infrared laser light irradiation on actin cytoskeleton reorganization in bone marrow mesenchymal stem cells. Cell Tissue Res 2020; 383:1003-1016. [PMID: 33159579 DOI: 10.1007/s00441-020-03306-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 09/17/2020] [Indexed: 11/29/2022]
Abstract
Tailoring the cell organelles and thus changing cell homeostatic behavior has permitted the discovery of fascinating metabolic features enabling enhanced viability, differentiation, or quenching inflammation. Recently, photobiomodulation (PBM) has been accredited as an effective cell manipulation technique with promising therapeutic potential. In this prospective, in vitro results revealed that 808-nm laser light emitted by a hand-piece with a flat-top profile at an irradiation set up of 60 J/cm2 (1 W, 1 W/cm2; 60 s, continuous wave) regulates bone marrow stromal cell (BMSC) differentiation toward osteogenesis. Considering the importance of actin cytoskeleton reorganization, which controls a range of cell metabolic activities, comprising shape change, proliferation and differentiation, the aim of the current work is to assess whether PBM therapy, using a flat-top hand-piece at higher-fluence irradiation on BMSCs, is able to switch photon signals into the stimulation of biochemical/differentiating pathways involving key activators that regulate de novo actin polymerization. Namely, for the first time, we unearthed the role of the flat-top hand-piece at higher-fluence irradiation on cytoskeletal characteristics of BMSCs. These novel findings meet the needs of novel therapeutically protocols provided by laser treatment and the manipulation of BMSCs as anti-inflammatory, osteo-inductive platforms.
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Affiliation(s)
- Andrea Amaroli
- Laser Therapy Centre, Department of Surgical and Diagnostic Sciences (D.I.S.C.), University of Genova, Genova, Italy
- Department of Orthopaedic Dentistry, Sechenov First Moscow State Medical University, Trubetzkaya St., 8, Bd. 2, 119991, Moscow, Russian Federation
| | - Maria Giovanna Sabbieti
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino (Macerata), Italy
| | - Luigi Marchetti
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino (Macerata), Italy
| | - Angelina O Zekiy
- Department of Orthopaedic Dentistry, Sechenov First Moscow State Medical University, Trubetzkaya St., 8, Bd. 2, 119991, Moscow, Russian Federation
| | - Anatoliy S Utyuzh
- Department of Orthopaedic Dentistry, Sechenov First Moscow State Medical University, Trubetzkaya St., 8, Bd. 2, 119991, Moscow, Russian Federation
| | - Andrea Marchegiani
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino (Macerata), Italy
| | - Fulvio Laus
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino (Macerata), Italy
| | - Vincenzo Cuteri
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino (Macerata), Italy
| | - Stefano Benedicenti
- Laser Therapy Centre, Department of Surgical and Diagnostic Sciences (D.I.S.C.), University of Genova, Genova, Italy
| | - Dimitrios Agas
- School of Biosciences and Veterinary Medicine, University of Camerino, Camerino (Macerata), Italy.
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12
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Shear Stress Modulates Osteoblast Cell and Nucleus Morphology and Volume. Int J Mol Sci 2020; 21:ijms21218361. [PMID: 33171812 PMCID: PMC7664694 DOI: 10.3390/ijms21218361] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 12/13/2022] Open
Abstract
Mechanical loading preserves bone mass and function—yet, little is known about the cell biological basis behind this preservation. For example, cell and nucleus morphology are critically important for cell function, but how these morphological characteristics are affected by the physiological mechanical loading of bone cells is under-investigated. This study aims to determine the effects of fluid shear stress on cell and nucleus morphology and volume of osteoblasts, and how these effects relate to changes in actin cytoskeleton and focal adhesion formation. Mouse calvaria 3T3-E1 (MC3T3-E1) osteoblasts were treated with or without 1 h pulsating fluid flow (PFF). Live-cell imaging was performed every 10 min during PFF and immediately after PFF. Cytoskeletal organization and focal adhesions were visualized, and gene and protein expression quantified. Two-dimensional (2D) and three-dimensional (3D) morphometric analyses were made using MeasureStack and medical imaging interaction toolkit (MITK) software. 2D-images revealed that 1 h PFF changed cell morphology from polygonal to triangular, and nucleus morphology from round to ellipsoid. PFF also reduced cell surface area (0.3-fold), cell volume (0.3-fold), and nucleus volume (0.2-fold). During PFF, the live-cell volume gradually decreased from 6000 to 3000 µm3. After PFF, α-tubulin orientation was more disorganized, but F-actin fluorescence intensity was enhanced, particularly around the nucleus. 3D-images obtained from Z-stacks indicated that PFF increased F-actin fluorescence signal distribution around the nucleus in the XZ and YZ direction (2.3-fold). PFF increased protein expression of phospho-paxillin (2.0-fold) and integrin-α5 (2.8-fold), but did not increase mRNA expression of paxillin-a (PXNA), paxillin-b (PXNB), integrin-α5 (ITGA51), or α-tubulin protein expression. In conclusion, PFF induced substantial changes in osteoblast cytoskeleton, as well as cell and nucleus morphology and volume, which was accompanied by elevated gene and protein expression of adhesion and structural proteins. More insights into the mechanisms whereby mechanical cues drive morphological changes in bone cells, and thereby, possibly in bone cell behavior, will aid the guidance of clinical treatment, particularly in the field of orthodontics, (oral) implantology, and orthopedics.
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Lewis KJ, Yi X, Wright CS, Pemberton EZ, Bullock WA, Thompson WR, Robling AG. The mTORC2 Component Rictor Is Required for Load-Induced Bone Formation in Late-Stage Skeletal Cells. JBMR Plus 2020; 4:e10366. [PMID: 32666017 PMCID: PMC7340445 DOI: 10.1002/jbm4.10366] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 03/17/2020] [Indexed: 12/14/2022] Open
Abstract
Bone relies on mechanical cues to build and maintain tissue composition and architecture. Our understanding of bone cell mechanotransduction continues to evolve, with a few key signaling pathways emerging as vital. Wnt/β‐catenin, for example, is essential for proper anabolic response to mechanical stimulation. One key complex that regulates β‐catenin activity is the mammalian target of rapamycin complex 2 (mTORc2). mTORc2 is critical for actin cytoskeletal reorganization, an indispensable component in mechanotransduction in certain cell types. In this study, we probed the impact of the mTORc2 signaling pathway in osteocyte mechanotransduction by conditionally deleting the mTORc2 subunit Rictor in Dmp1‐expressing cells of C57BL/6 mice. Conditional deletion of the Rictor was achieved using the Dmp1–Cre driver to recombine Rictor floxed alleles. Rictor mutants exhibited a decrease in skeletal properties, as measured by DXA, μCT, and mechanical testing, compared with Cre‐negative floxed littermate controls. in vivo axial tibia loading conducted in adult mice revealed a deficiency in the osteogenic response to loading among Rictor mutants. Histological measurements of osteocyte morphology indicated fewer, shorter cell processes in Rictor mutants, which might explain the compromised response to mechanical stimulation. In summary, inhibition of the mTORc2 pathway in late osteoblasts/osteocytes leads to decreased bone mass and mechanically induced bone formation. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Karl J Lewis
- Department of Anatomy & Cell Biology Indiana University School of Medicine Indianapolis IN USA
| | - Xin Yi
- Department of Physical Therapy Indiana University School of Health & Human Sciences Indianapolis IN USA
| | - Christian S Wright
- Department of Physical Therapy Indiana University School of Health & Human Sciences Indianapolis IN USA
| | - Emily Z Pemberton
- Department of Anatomy & Cell Biology Indiana University School of Medicine Indianapolis IN USA
| | - Whitney A Bullock
- Department of Anatomy & Cell Biology Indiana University School of Medicine Indianapolis IN USA
| | - William R Thompson
- Department of Physical Therapy Indiana University School of Health & Human Sciences Indianapolis IN USA.,Indiana Center for Musculoskeletal Health Indianapolis IN USA
| | - Alexander G Robling
- Department of Anatomy & Cell Biology Indiana University School of Medicine Indianapolis IN USA.,Indiana Center for Musculoskeletal Health Indianapolis IN USA.,Department of Biomedical Engineering Indiana University-Purdue University at Indianapolis Indianapolis IN USA.,Richard L. Roudebush VA Medical Center Indianapolis IN USA
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14
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Cepeda SB, Sandoval MJ, Crescitelli MC, Rauschemberger MB, Massheimer VL. The isoflavone genistein enhances osteoblastogenesis: signaling pathways involved. J Physiol Biochem 2020; 76:99-110. [DOI: 10.1007/s13105-019-00722-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 12/11/2019] [Indexed: 11/24/2022]
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15
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Crescitelli MC, Rauschemberger MB, Cepeda S, Sandoval M, Massheimer VL. Role of estrone on the regulation of osteoblastogenesis. Mol Cell Endocrinol 2019; 498:110582. [PMID: 31525430 DOI: 10.1016/j.mce.2019.110582] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 09/12/2019] [Accepted: 09/13/2019] [Indexed: 11/19/2022]
Abstract
Although estradiol bone contribution has been deeply studied, little is known about the action of estrone. We investigated the direct action of estrone on osteoblasts growth and differentiation, with focus on the biochemical mechanism displayed by the estrogen. Murine calvarial osteoblast cultures in vitro exposed to 10 nM estrone were employed. Estrone enhanced gene expression of the osteogenic differentiation marker, Runx2 mRNA (150% above control). The hormone significantly increased cell proliferation (38% above control), nitric oxide production (108% above control), alkaline phosphatase activity (50% above control), in addition to stimulation of extracellular matrix mineralization. Using specific antagonists, we found that the mechanism of action of estrone involves estrogen receptor, nitric oxide synthase and MAPK signalling pathways participation. The hormone acts by its own and probably not via conversion to estradiol, since 17 B HSD inhibition did not affect the hormonal action. This work shows a novel action of estrone on bone cells promoting osteoblastogenesis.
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Affiliation(s)
- M Carla Crescitelli
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS), San Juan 670, B8000ICN, Bahía Blanca, Argentina; Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-UNS), Argentina
| | - M Belén Rauschemberger
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS), San Juan 670, B8000ICN, Bahía Blanca, Argentina; Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-UNS), Argentina
| | - Sabrina Cepeda
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS), San Juan 670, B8000ICN, Bahía Blanca, Argentina; Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-UNS), Argentina
| | - Marisa Sandoval
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS), San Juan 670, B8000ICN, Bahía Blanca, Argentina; Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-UNS), Argentina
| | - Virginia L Massheimer
- Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS), San Juan 670, B8000ICN, Bahía Blanca, Argentina; Instituto de Ciencias Biológicas y Biomédicas del Sur (INBIOSUR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-UNS), Argentina.
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16
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Nagayama K, Miyamoto Y, Kaneko K, Yoshimura K, Sasa K, Akaike T, Fujii S, Izumida E, Uyama R, Chikazu D, Maki K, Kamijo R. Production of 8-nitro-cGMP in osteocytic cells and its upregulation by parathyroid hormone and prostaglandin E 2. In Vitro Cell Dev Biol Anim 2018; 55:45-51. [PMID: 30397855 DOI: 10.1007/s11626-018-0304-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 10/19/2018] [Indexed: 01/05/2023]
Abstract
Osteocytes regulate bone remodeling, especially in response to mechanical loading and unloading of bone, with nitric oxide reported to play an important role in that process. In the present study, we found that 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP), a second messenger of nitric oxide in various types of cells, was produced by osteocytes in bone tissue as well as cultured osteocytic Ocy454 cells. The amount of 8-nitro-cGMP in Ocy454 cells increased during incubation with parathyroid hormone or prostaglandin E2, both of which are known to upregulate receptor activator of nuclear factor-κB ligand (RANKL) mRNA expression in osteocytes. On the other hand, exogenous 8-nitro-cGMP did not have effects on either the presence or absence of these bioactive substances. Furthermore, neither an inhibitor of nitric oxide synthase nor 8-bromo-cGMP, a cell-permeable analog of cGMP, showed remarkable effects on mRNA expression of sclerostin or RANKL. These results indicate that neither nitric oxide nor its downstream compounds, including 8-nitro-cGMP, alone are sufficient for induction of functional changes in osteocytes.
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Affiliation(s)
- Kazuhiro Nagayama
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Department of Orthodontics, Showa University School of Dentistry, Shinagawa, Japan
| | - Yoichi Miyamoto
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.
| | - Kotaro Kaneko
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.,Department of Oral and Maxillofacial Surgery, Tokyo Medical University, Shinjuku, Japan
| | - Kentaro Yoshimura
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Kiyohito Sasa
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Takaaki Akaike
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Shigemoto Fujii
- Department of Environmental Health Sciences and Molecular Toxicology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Eri Izumida
- Department of Orthodontics, Showa University School of Dentistry, Shinagawa, Japan
| | - Risa Uyama
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Daichi Chikazu
- Department of Oral and Maxillofacial Surgery, Tokyo Medical University, Shinjuku, Japan
| | - Koutaro Maki
- Department of Orthodontics, Showa University School of Dentistry, Shinagawa, Japan
| | - Ryutaro Kamijo
- Department of Biochemistry, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
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17
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Lombardo MC, Lamattina L. Abscisic acid and nitric oxide modulate cytoskeleton organization, root hair growth and ectopic hair formation in Arabidopsis. Nitric Oxide 2018; 80:89-97. [PMID: 30236618 DOI: 10.1016/j.niox.2018.09.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 07/26/2018] [Accepted: 09/15/2018] [Indexed: 12/13/2022]
Abstract
Abscisic acid (ABA) and nitric oxide (NO) are two plant growth regulators that participate in many signaling cascades in different organs all along the plant life. Here, we were interested in deciphering the effects of ABA and NO on the cytoskeleton organization in a model of polarized cell growth like root hairs. Arabidopsis roots were exposed to different concentrations of ABA, and the length of primary root, epidermal cells and root hairs were measured. The NO concentration was detected with the NO-specific fluorescent probe DAF-FM DA. To quantify the effects of ABA and NO on cytoskeleton, Arabidopsis seedlings expressing GFP-MAP4 were used to analyze microtubules (MTs) orientation. Changes in cytoplasmic streaming were quantified through fluorescence recovery after photobleaching (FRAP) experiments using confocal laser scanning microscopy (CLSM) and the probe fluorescein diacetate (FDA). Results indicate that ABA decreases root hair length and induces the differentiation of atrichoblasts into trichoblasts, increasing root hair density. ABA also triggers an increase of NO level in root hairs. Both, ABA and NO affect MT organization in root hairs. While root hairs show MT orientation close to the longitudinal axis in control roots, ABA and NO treatments induce the oblique orientation of MTs. In parallel, cytoplasmic flow, executed by actin cytoskeleton, is enhanced by NO, in an ABA-independent manner. For all experimental conditions assayed, basal levels of NO are required to keep MT organization and cytoplasmic streaming. Our findings support ABA and NO as key modulators of growth and ectopic formation of root hairs through actions on cytoskeleton functions.
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Affiliation(s)
- María Cristina Lombardo
- Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata and Consejo Nacional de Investigaciones Científicas y Técnicas, Mar del Plata, Argentina
| | - Lorenzo Lamattina
- Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata and Consejo Nacional de Investigaciones Científicas y Técnicas, CC 1245, 7600, Mar del Plata, Argentina.
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18
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Morrell AE, Brown GN, Robinson ST, Sattler RL, Baik AD, Zhen G, Cao X, Bonewald LF, Jin W, Kam LC, Guo XE. Mechanically induced Ca 2+ oscillations in osteocytes release extracellular vesicles and enhance bone formation. Bone Res 2018; 6:6. [PMID: 29581909 PMCID: PMC5859015 DOI: 10.1038/s41413-018-0007-x] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 11/23/2017] [Indexed: 02/01/2023] Open
Abstract
The vast osteocytic network is believed to orchestrate bone metabolic activity in response to mechanical stimuli through production of sclerostin, RANKL, and osteoprotegerin (OPG). However, the mechanisms of osteocyte mechanotransduction remain poorly understood. We've previously shown that osteocyte mechanosensitivity is encoded through unique intracellular calcium (Ca2+) dynamics. Here, by simultaneously monitoring Ca2+ and actin dynamics in single cells exposed to fluid shear flow, we detected actin network contractions immediately upon onset of flow-induced Ca2+ transients, which were facilitated by smooth muscle myosin and further confirmed in native osteocytes ex vivo. Actomyosin contractions have been linked to the secretion of extracellular vesicles (EVs), and our studies demonstrate that mechanical stimulation upregulates EV production in osteocytes through immunostaining for the secretory vesicle marker Lysosomal-associated membrane protein 1 (LAMP1) and quantifying EV release in conditioned medium, both of which are blunted when Ca2+ signaling was inhibited by neomycin. Axial tibia compression was used to induce anabolic bone formation responses in mice, revealing upregulated LAMP1 and expected downregulation of sclerostin in vivo. This load-related increase in LAMP1 expression was inhibited in neomycin-injected mice compared to vehicle. Micro-computed tomography revealed significant load-related increases in both trabecular bone volume fraction and cortical thickness after two weeks of loading, which were blunted by neomycin treatment. In summary, we found mechanical stimulation of osteocytes activates Ca2+-dependent contractions and enhances the production and release of EVs containing bone regulatory proteins. Further, blocking Ca2+ signaling significantly attenuates adaptation to mechanical loading in vivo, suggesting a critical role for Ca2+-mediated signaling in bone adaptation.
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Affiliation(s)
- Andrea E. Morrell
- Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY USA
| | - Genevieve N. Brown
- Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY USA
| | - Samuel T. Robinson
- Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY USA
| | - Rachel L. Sattler
- Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY USA
| | - Andrew D. Baik
- Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY USA
| | - Gehua Zhen
- Center for Musculoskeletal Research, Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD USA
| | - Xu Cao
- Center for Musculoskeletal Research, Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, MD USA
| | - Lynda F. Bonewald
- Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, IN USA
| | - Weiyang Jin
- Microscale Biocomplexity Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY USA
| | - Lance C. Kam
- Microscale Biocomplexity Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY USA
| | - X. Edward Guo
- Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY USA
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19
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Budyn E, Gaci N, Sanders S, Bensidhoum M, Schmidt E, Cinquin B, Tauc P, Petite H. Human Stem Cell Derived Osteocytes in Bone-on-Chip. ACTA ACUST UNITED AC 2018. [DOI: 10.1557/adv.2018.278] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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20
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Cresswell EN, Nguyen TM, Horsfield MW, Alepuz AJ, Metzger TA, Niebur GL, Hernandez CJ. Mechanically induced bone formation is not sensitive to local osteocyte density in rat vertebral cancellous bone. J Orthop Res 2018; 36:672-681. [PMID: 28513889 DOI: 10.1002/jor.23606] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Accepted: 05/10/2017] [Indexed: 02/04/2023]
Abstract
Osteocytes play an integral role in bone by sensing mechanical stimuli and releasing signaling factors that direct bone formation. The importance of osteocytes in mechanotransduction suggests that regions of bone tissue with greater osteocyte populations are more responsive to mechanical stimuli. To determine the effects of osteocyte population on bone functional adaptation we applied mechanical loads to the 8th caudal vertebra of skeletally mature female Sprague Dawley rats (6 months of age, n = 8 loaded, n = 8 sham controls). The distribution of tissue stress/strain within cancellous bone was determined using high-resolution finite element models, osteocyte distribution was determined using nano-computed tomography, and locations of bone formation were determined using three-dimensional images of fluorescent bone formation markers. Loading increased bone formation (3D MS/BS 10.82 ± 2.09% in loaded v. 3.17 ± 2.05% in sham control, mean ± SD). Bone formation occurred at regions of cancellous bone experiencing greater tissue stress/strain, however stress/strain was only a modest predictor of bone formation; even at locations of greatest stress/strain the probability of observing bone formation did not exceed 41%. The local osteocyte population was not correlated with locations of new bone formation. The findings support the idea that local tissue stress/strain influence the locations of bone formation in cancellous bone, but suggest that the size of the osteocyte population itself is not influential. We conclude that other aspects of osteocytes such as osteocyte connectivity, lacunocanilicular nano-geometry, and/or fluid pressure/shear distributions within the marrow space may be more influential in regulating bone mechanotransduction than the number of osteocytes. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:672-681, 2018.
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Affiliation(s)
- Erin N Cresswell
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York.,Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York
| | - Thu M Nguyen
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York
| | - Michael W Horsfield
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York
| | - Adrian J Alepuz
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York
| | - Thomas A Metzger
- Bioengineering Graduate Program, University of Notre Dame, Notre Dame, Indiana
| | - Glen L Niebur
- Bioengineering Graduate Program, University of Notre Dame, Notre Dame, Indiana
| | - Christopher J Hernandez
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York.,Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York.,Hospital for Special Surgery, New York, New York
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21
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Li Y, Yuan J, Wang Q, Sun L, Sha Y, Li Y, Wang L, Wang Z, Ma Y, Cao H. The collective influence of 1, 25-dihydroxyvitamin D 3 with physiological fluid shear stress on osteoblasts. Steroids 2018; 129:9-16. [PMID: 29155218 DOI: 10.1016/j.steroids.2017.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 09/23/2017] [Accepted: 11/12/2017] [Indexed: 11/27/2022]
Abstract
1, 25-dihydroxyvitamin D3 (1, 25 (OH)2 D3) and mechanical stimuli in physiological environment contributes greatly to osteoporosis pathogenesis. Wide investigations have been conducted on how 1, 25-dihydroxyvitamin D3 and mechanical stimuli separately impact osteoblasts. This study reports the collective influences of 1, 25-dihydroxyvitamin D3 and flow shear stress (FSS) on biological functions of osteoblasts. 1, 25 (OH)2 D3 were prepared in various kinds of concentrations (0, 1, 10, 100 nmmol/L), while physiological fluid shear stress (12 dynes/cm2) was produced by using a parallel-plate fluid flow system. 1, 25 (OH)2 D3 affects the responses of ROBs to FSS, including the inhibition of NO release and cell proliferation as well as the promotion of PGE2 release and cell differentiation. These findings provide a possible mechanism by which 1, 25(OH)2 D3 influences osteoblasts' responses to FSS, thus most probably providing guidance for the selection of 1, 25(OH)2 D3 concentration and mechanical loading in order to produce functional bone tissues in vitro.
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Affiliation(s)
- Yan Li
- School of Pharmacy, Taizhou Polytechnic College, Taizhou 225300, China; Bone Tissue Engineering Research Center of Taizhou, Taizhou 225300, China.
| | - Jiafeng Yuan
- School of Pharmacy, Taizhou Polytechnic College, Taizhou 225300, China; Bone Tissue Engineering Research Center of Taizhou, Taizhou 225300, China
| | - Qianwen Wang
- School of Pharmacy, Taizhou Polytechnic College, Taizhou 225300, China; Bone Tissue Engineering Research Center of Taizhou, Taizhou 225300, China
| | - Lijie Sun
- School of Pharmacy, Taizhou Polytechnic College, Taizhou 225300, China; Bone Tissue Engineering Research Center of Taizhou, Taizhou 225300, China
| | - Yunying Sha
- School of Pharmacy, Taizhou Polytechnic College, Taizhou 225300, China; Bone Tissue Engineering Research Center of Taizhou, Taizhou 225300, China
| | - Yanxiang Li
- School of Pharmacy, Taizhou Polytechnic College, Taizhou 225300, China; Bone Tissue Engineering Research Center of Taizhou, Taizhou 225300, China
| | - Lizhong Wang
- School of Pharmacy, Taizhou Polytechnic College, Taizhou 225300, China; Bone Tissue Engineering Research Center of Taizhou, Taizhou 225300, China
| | - Zhonghua Wang
- School of Pharmacy, Taizhou Polytechnic College, Taizhou 225300, China; Bone Tissue Engineering Research Center of Taizhou, Taizhou 225300, China
| | - Yonggang Ma
- School of Pharmacy, Taizhou Polytechnic College, Taizhou 225300, China; Bone Tissue Engineering Research Center of Taizhou, Taizhou 225300, China
| | - Hui Cao
- School of Pharmacy, Taizhou Polytechnic College, Taizhou 225300, China; Bone Tissue Engineering Research Center of Taizhou, Taizhou 225300, China
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22
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Cao R, Xiao W, Wu X, Sun L, Pan F. Quantitative observations on cytoskeleton changes of osteocytes at different cell parts using digital holographic microscopy. BIOMEDICAL OPTICS EXPRESS 2018; 9:72-85. [PMID: 29359088 PMCID: PMC5772590 DOI: 10.1364/boe.9.000072] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 11/30/2017] [Accepted: 11/30/2017] [Indexed: 05/10/2023]
Abstract
Cytoskeletons such as F-actin have different distributions in different cell parts and they are the cause of different degrees of cell collapse when the F-actin is disrupted. It is challenging to use conventional methods such as fluorescence microscopy and atomic force microscopy to conduct real-time and three-dimensional observations on the dynamic processes at different cell parts due to the slow measuring speed and the need for live-cell staining. In this study, the morphological variations of different bone cell parts caused by F-actin disruption are dynamically measured by using digital holographic microscopy (DHM). We separately analyze local parameters (cell height and cell width) and global parameters (cell projected area and cell volume) of cells to address variations of specific cell areas and quantify the changing process of the whole cell. We found significant differences in temporal variations of both local and global cell parameters between the cell body and cell process, which is consistent with the qualitative observation by fluorescence staining. Our study not only validates the unique ability of DHM to simultaneously investigate the dynamic process at different cell parts, but also provides sufficient experimental bases for exploring the mechanism for F-actin disruption.
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Affiliation(s)
- Runyu Cao
- Key Laboratory of Precision Opto-Mechatronics Technology of Ministry of Education, School of Instrumentation Science & Optoelectronics Engineering, Beihang University, Beijing, 100191, China
| | - Wen Xiao
- Key Laboratory of Precision Opto-Mechatronics Technology of Ministry of Education, School of Instrumentation Science & Optoelectronics Engineering, Beihang University, Beijing, 100191, China
| | - Xintong Wu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100191, China
| | - Lianwen Sun
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100191, China
| | - Feng Pan
- Key Laboratory of Precision Opto-Mechatronics Technology of Ministry of Education, School of Instrumentation Science & Optoelectronics Engineering, Beihang University, Beijing, 100191, China
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23
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Abstract
PURPOSE OF REVIEW The bone is able to adapt its structure to mechanical signals via the bone remodeling process governed by mechanosensitive osteocytes. With aging, an imbalance in bone remodeling results in osteoporosis. In this review, we hypothesized that changes in lacunar morphology underlie the decreased bone mechanoresponsiveness to mechanical loading with aging. RECENT FINDINGS Several studies have reported considerable variations in the shape of osteocytes and their lacunae with aging. Since osteocytes can sense matrix strain directly via their cell bodies, the variations in osteocyte morphology may cause changes in osteocyte mechanosensitivity. As a consequence, the load-adaptive response of osteocytes may change with aging, even when mechanical loading would remain unchanged. Though extensive quantitative data is lacking, evidence exists that the osteocyte lacunae are becoming smaller and more spherical with aging. Future dedicated studies might reveal whether these changes would affect osteocyte mechanosensation and the subsequent biological response, and whether this is (one of) the pathways involved in age-related bone loss.
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Affiliation(s)
- Haniyeh Hemmatian
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300c, 3001 Leuven, Belgium
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Astrid D. Bakker
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Jenneke Klein-Nulend
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - G. Harry van Lenthe
- Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300c, 3001 Leuven, Belgium
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24
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Kämmerer PW, Thiem DGE, Alshihri A, Wittstock GH, Bader R, Al-Nawas B, Klein MO. Cellular fluid shear stress on implant surfaces-establishment of a novel experimental set up. Int J Implant Dent 2017; 3:22. [PMID: 28567712 PMCID: PMC5451379 DOI: 10.1186/s40729-017-0085-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 05/22/2017] [Indexed: 12/22/2022] Open
Abstract
Background Mechanostimuli of different cells can affect a wide array of cellular and inter-cellular biological processes responsible for dental implant healing. The purpose of this in vitro study was to establish a new test model to create a reproducible flow-induced fluid shear stress (FSS) of osteoblast cells on implant surfaces. Methods As FSS effects on osteoblasts are detectable at 10 dyn/cm2, a custom-made flow chamber was created. Computer-aided verification of circulation processes was performed. In order to verify FSS effects, cells were analysed via light and fluorescence microscopy. Results Utilising computer-aided simulations, the underside of the upper plate was considered to have optimal conditions for cell culturing. At this site, a flow-induced orientation of osteoblast cell clusters and an altered cell morphology with cellular elongation and alteration of actin fibres in the fluid flow direction was detected. Conclusions FSS simulation using this novel flow chamber might mimic the peri-implant situation in the phase of loaded implant healing. With this FSS flow chamber, osteoblast cells’ sensitivity to FSS was verified in the form of morphological changes and cell re-clustering towards the direction of the flow. Different shear forces can be created simultaneously in a single experiment.
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Affiliation(s)
- P W Kämmerer
- Department of Oral and Maxillofacial Surgery, Facial Plastic Surgery, University Medical Centre Rostock, Schillingallee 35, 18057, Rostock, Germany
| | - D G E Thiem
- Department of Oral and Maxillofacial Surgery, Facial Plastic Surgery, University Medical Centre Rostock, Schillingallee 35, 18057, Rostock, Germany.
| | - A Alshihri
- Department of Prosthetic and Biomaterial Sciences, King Saud University, Riyadh, Saudi Arabia.,Harvard School of Dental Medicine, Boston, MA, USA
| | - G H Wittstock
- Department of Oral and Maxillofacial Surgery, Plastic Surgery, University Medical Centre Mainz, Mainz, Germany
| | - R Bader
- Department of Orthopedics, University Medical Centre Rostock, Rostock, Germany
| | - B Al-Nawas
- Department of Oral and Maxillofacial Surgery, Plastic Surgery, University Medical Centre Mainz, Mainz, Germany
| | - M O Klein
- Department of Oral and Maxillofacial Surgery, Plastic Surgery, University Medical Centre Mainz, Mainz, Germany
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25
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Deepak V, Kayastha P, McNamara LM. Estrogen deficiency attenuates fluid flow‐induced [Ca
2+
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oscillations and mechanoresponsiveness of MLO‐Y4 osteocytes. FASEB J 2017; 31:3027-3039. [DOI: 10.1096/fj.201601280r] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 03/13/2017] [Indexed: 01/19/2023]
Affiliation(s)
- Vishwa Deepak
- Mechanobiology and Medical Device Research GroupBiomechanics Research CentreBiomedical EngineeringCollege of Engineering and InformaticsNational University of Ireland GalwayGalway Ireland
| | - Pushpalata Kayastha
- Mechanobiology and Medical Device Research GroupBiomechanics Research CentreBiomedical EngineeringCollege of Engineering and InformaticsNational University of Ireland GalwayGalway Ireland
| | - Laoise M. McNamara
- Mechanobiology and Medical Device Research GroupBiomechanics Research CentreBiomedical EngineeringCollege of Engineering and InformaticsNational University of Ireland GalwayGalway Ireland
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26
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Xu H, Ning D, Zhao D, Chen Y, Zhao D, Gu S, Jiang JX, Shang P. Blockage of hemichannels alters gene expression in osteocytes in a high magneto-gravitational environment. Front Biosci (Landmark Ed) 2017; 22:783-794. [PMID: 27814646 DOI: 10.2741/4516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Osteocytes, the most abundant cells in bone, are highly responsive to external environmental changes. We tested how Cx43 hemichannels which mediate the exchange of small molecules between cells and extracellular environment impact genome wide gene expression under conditions of abnormal gravity and magnetic field. To this end, we subjected osteocytic MLO-Y4 cells to a high magneto-gravitational environment and used microarray to examine global gene expression and a specific blocking antibody was used to assess the role of Cx43 hemichannels. While 3 hr exposure to abnormal gravity and magnetic field had relatively minor effects on global gene expression, blocking hemichannels significantly impacted the expression of a number of genes which are involved in cell viability, apoptosis, mineral absorption, protein absorption and digestion, and focal adhesion. Also, blocking of hemichannels enriched genes in multiple signaling pathways which are enaged by TGF-beta, Jak-STAT and VEGF. These results show the role of connexin hemichannels in bone cells in high magneto-gravitational environments.
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Affiliation(s)
- Huiyun Xu
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi Province, 710072, China
| | - Dandan Ning
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi Province, 710072, China
| | - Dezhi Zhao
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi Province, 710072, China
| | - Yunhe Chen
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi Province, 710072, China
| | - Dongdong Zhao
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi Province, 710072, China
| | - Sumin Gu
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, Texas, 78229, USA
| | - Jean Xin Jiang
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, Texas, 78229, USA
| | - Peng Shang
- Key Laboratory for Space Biosciences and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi Province, 710072, China,
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Giorgi M, Verbruggen SW, Lacroix D. In silico bone mechanobiology: modeling a multifaceted biological system. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2016; 8:485-505. [PMID: 27600060 PMCID: PMC5082538 DOI: 10.1002/wsbm.1356] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 06/27/2016] [Accepted: 07/27/2016] [Indexed: 12/04/2022]
Abstract
Mechanobiology, the study of the influence of mechanical loads on biological processes through signaling to cells, is fundamental to the inherent ability of bone tissue to adapt its structure in response to mechanical stimulation. The immense contribution of computational modeling to the nascent field of bone mechanobiology is indisputable, having aided in the interpretation of experimental findings and identified new avenues of inquiry. Indeed, advances in computational modeling have spurred the development of this field, shedding new light on problems ranging from the mechanical response to loading by individual cells to tissue differentiation during events such as fracture healing. To date, in silico bone mechanobiology has generally taken a reductive approach in attempting to answer discrete biological research questions, with research in the field broadly separated into two streams: (1) mechanoregulation algorithms for predicting mechanobiological changes to bone tissue and (2) models investigating cell mechanobiology. Future models will likely take advantage of advances in computational power and techniques, allowing multiscale and multiphysics modeling to tie the many separate but related biological responses to loading together as part of a larger systems biology approach to shed further light on bone mechanobiology. Finally, although the ever‐increasing complexity of computational mechanobiology models will inevitably move the field toward patient‐specific models in the clinic, the determination of the context in which they can be used safely for clinical purpose will still require an extensive combination of computational and experimental techniques applied to in vitro and in vivo applications. WIREs Syst Biol Med 2016, 8:485–505. doi: 10.1002/wsbm.1356 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Mario Giorgi
- Department of Oncology and Metabolism and INSIGNEO Institute for In Silico Medicine, University of Sheffield, Sheffield, UK
| | | | - Damien Lacroix
- INSIGNEO Institute for In Silico Medicine, Department of Mechanical Engineering, University of Sheffield, Sheffield, UK.
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28
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Maurel DB, Duan P, Farr J, Cheng AL, Johnson ML, Bonewald LF. Beta-Catenin Haplo Insufficient Male Mice Do Not Lose Bone in Response to Hindlimb Unloading. PLoS One 2016; 11:e0158381. [PMID: 27410430 PMCID: PMC4943721 DOI: 10.1371/journal.pone.0158381] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 06/15/2016] [Indexed: 11/19/2022] Open
Abstract
As the β-catenin pathway has been shown to be involved in mechanotransduction, we sought to determine if haploinsufficiency would affect skeletal response to unloading. It has previously been shown that deletion of both alleles of β-catenin in bone cells results in a fragile skeleton highly susceptible to fracture, but deletion of one allele using Dmp1-Cre (Ctnnb1+/loxP; Dmp1-Cre, cKO HET) has little effect on the 2 mo old skeleton. We found that under normal housing conditions, trabecular bone volume was significantly less in 5 mo old male cKO HET mice compared to controls (Ctrl/HET:Tb. BV/TV = 13.96±2.71/8.92±0.95%, Tb.N. = 4.88±0.51/3.95±0.44/mm, Tb. Sp. = 0.20±0.02/0.26±0.03mm, a 36%, 19% and 30% change respectively) but not in females suggesting an age and gender related effect. Before performing suspension experiments and to control for the environmental effects, animals with the same tail attachment and housing conditions, but not suspended (NS), were compared to normally housed (NH) animals. Attachment and housing resulted in weight loss in both genders and phenotypes. Cortical bone loss was observed in the cKO HET males (NH/NS, Ct BV/TV: 90.45±0.72/89.12±0.56%) and both diaphyseal (0.19±0.01/0.17±0.01mm) and metaphyseal (0.10±0.01/0.08±0.01mm) thickness, but not in female cKO HET mice suggesting that male cKO HET mice are susceptible to attachment and housing conditions. These results with transgenic mice emphasizes the importance of proper controls when attributing skeletal responses to unloading. With suspension, cKO HET male mice did not lose bone unlike female cKO HET mice that had greater trabecular bone loss than controls (Ctrl 9%:cKO HET 21% decrease Tb. N; Ctrl 12%:cKO HET 27% increase Tb. Sp.). Suspended and non-suspended mice lost weight compared to normally housed animals. Taken together, the data suggest a protective effect of β-catenin against the effects of stress in males and partial protection against unloading in females.
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Affiliation(s)
- Delphine B. Maurel
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, United States of America
| | - Peipei Duan
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, United States of America
| | - Joshua Farr
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, United States of America
| | - An-Lin Cheng
- School of Nursing and Health Studies, University of Missouri-Kansas City, Kansas City, MO, United States of America
| | - Mark L. Johnson
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, United States of America
| | - Lynda F. Bonewald
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, United States of America
- * E-mail:
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29
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Liu C, Cui X, Ackermann TM, Flamini V, Chen W, Castillo AB. Osteoblast-derived paracrine factors regulate angiogenesis in response to mechanical stimulation. Integr Biol (Camb) 2016; 8:785-94. [PMID: 27332785 PMCID: PMC8274385 DOI: 10.1039/c6ib00070c] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Angiogenesis is a process by which new blood vessels emerge from existing vessels through endothelial cell sprouting, migration, proliferation, and tubule formation. Angiogenesis during skeletal growth, homeostasis and repair is a complex and incompletely understood process. As the skeleton adapts to mechanical loading, we hypothesized that mechanical stimulation regulates "osteo-angio" crosstalk in the context of angiogenesis. We showed that conditioned media (CM) from osteoblasts exposed to fluid shear stress enhanced endothelial cell proliferation and migration, but not tubule formation, relative to CM from static cultures. Endothelial cell sprouting was studied using a dual-channel collagen gel-based microfluidic device that mimics vessel geometry. Static CM enhanced endothelial cell sprouting frequency, whereas loaded CM significantly enhanced both frequency and length. Both sprouting frequency and length were significantly enhanced in response to factors released from osteoblasts exposed to fluid shear stress in an adjacent channel. Osteoblasts released angiogenic factors, of which osteopontin, PDGF-AA, IGBP-2, MCP-1, and Pentraxin-3 were upregulated in response to mechanical loading. These data suggest that in vivo mechanical forces regulate angiogenesis in bone by modulating "osteo-angio" crosstalk through release of paracrine factors, which we term "osteokines".
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Affiliation(s)
- Chao Liu
- Department of Mechanical and Aerospace Engineering, Tandon School of Engineering, New York University, Brooklyn, NY 11201, USA. and Department of Orthopaedic Surgery, New York University School of Medicine, New York, NY 10003, USA
| | - Xin Cui
- Department of Mechanical and Aerospace Engineering, Tandon School of Engineering, New York University, Brooklyn, NY 11201, USA.
| | - Thomas M Ackermann
- Department of Mechanical and Aerospace Engineering, Tandon School of Engineering, New York University, Brooklyn, NY 11201, USA.
| | - Vittoria Flamini
- Department of Mechanical and Aerospace Engineering, Tandon School of Engineering, New York University, Brooklyn, NY 11201, USA.
| | - Weiqiang Chen
- Department of Mechanical and Aerospace Engineering, Tandon School of Engineering, New York University, Brooklyn, NY 11201, USA.
| | - Alesha B Castillo
- Department of Mechanical and Aerospace Engineering, Tandon School of Engineering, New York University, Brooklyn, NY 11201, USA. and Department of Orthopaedic Surgery, New York University School of Medicine, New York, NY 10003, USA
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30
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Brown GN, Sattler RL, Guo XE. Experimental studies of bone mechanoadaptation: bridging in vitro and in vivo studies with multiscale systems. Interface Focus 2016; 6:20150071. [PMID: 26855756 DOI: 10.1098/rsfs.2015.0071] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Despite advancements in technology and science over the last century, the mechanisms underlying Wolff's law-bone structure adaptation in response to physical stimuli-remain poorly understood, limiting the ability to effectively treat and prevent skeletal diseases. A challenge to overcome in the study of the underlying mechanisms of this principle is the multiscale nature of mechanoadaptation. While there exist in silico systems that are capable of studying across these scales, experimental studies are typically limited to interpretation at a single dimension or time point. For instance, studies of single-cell responses to defined physical stimuli offer only a limited prediction of the whole bone response, while overlapping pathways or compensatory mechanisms complicate the ability to isolate critical targets in a whole animal model. Thus, there exists a need to develop experimental systems capable of bridging traditional experimental approaches and informing existing multiscale theoretical models. The purpose of this article is to review the process of mechanoadaptation and inherent challenges in studying its underlying mechanisms, discuss the limitations of traditional experimental systems in capturing the many facets of this process and highlight three multiscale experimental systems which bridge traditional approaches and cover relatively understudied time and length scales in bone adaptation.
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Affiliation(s)
- Genevieve N Brown
- Bone Bioengineering Laboratory, Department of Biomedical Engineering , Columbia University , New York, NY 10027 , USA
| | - Rachel L Sattler
- Bone Bioengineering Laboratory, Department of Biomedical Engineering , Columbia University , New York, NY 10027 , USA
| | - X Edward Guo
- Bone Bioengineering Laboratory, Department of Biomedical Engineering , Columbia University , New York, NY 10027 , USA
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31
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Lu J, Fan Y, Gong X, Zhou X, Yi C, Zhang Y, Pan J. The Lineage Specification of Mesenchymal Stem Cells Is Directed by the Rate of Fluid Shear Stress. J Cell Physiol 2016; 231:1752-60. [DOI: 10.1002/jcp.25278] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 12/03/2015] [Indexed: 12/14/2022]
Affiliation(s)
- Juan Lu
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, College of Bioengineering; Chongqing University; Chongqing China
| | - Yijuan Fan
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, College of Bioengineering; Chongqing University; Chongqing China
| | - Xiaoyuan Gong
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, College of Bioengineering; Chongqing University; Chongqing China
| | - Xin Zhou
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, College of Bioengineering; Chongqing University; Chongqing China
| | - Caixia Yi
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, College of Bioengineering; Chongqing University; Chongqing China
| | - Yinxing Zhang
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, College of Bioengineering; Chongqing University; Chongqing China
| | - Jun Pan
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, College of Bioengineering; Chongqing University; Chongqing China
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32
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Goodman CA, Hornberger TA, Robling AG. Bone and skeletal muscle: Key players in mechanotransduction and potential overlapping mechanisms. Bone 2015; 80:24-36. [PMID: 26453495 PMCID: PMC4600534 DOI: 10.1016/j.bone.2015.04.014] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 03/18/2015] [Accepted: 04/07/2015] [Indexed: 12/16/2022]
Abstract
The development and maintenance of skeletal muscle and bone mass is critical for movement, health and issues associated with the quality of life. Skeletal muscle and bone mass are regulated by a variety of factors that include changes in mechanical loading. Moreover, bone mass is, in large part, regulated by muscle-derived mechanical forces and thus by changes in muscle mass/strength. A thorough understanding of the cellular mechanism(s) responsible for mechanotransduction in bone and skeletal muscle is essential for the development of effective exercise and pharmaceutical strategies aimed at increasing, and/or preventing the loss of, mass in these tissues. Thus, in this review we will attempt to summarize the current evidence for the major molecular mechanisms involved in mechanotransduction in skeletal muscle and bone. By examining the differences and similarities in mechanotransduction between these two tissues, it is hoped that this review will stimulate new insights and ideas for future research and promote collaboration between bone and muscle biologists.(1).
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Affiliation(s)
- Craig A Goodman
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA; Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, Melbourne, Australia; Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Melbourne, VIC, Australia.
| | - Troy A Hornberger
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Alexander G Robling
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA; Roudebush Veterans Affairs Medical Center, Indianapolis, IN 46202, USA; Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN 46202, USA
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Klein-Nulend J, van Oers RFM, Bakker AD, Bacabac RG. Bone cell mechanosensitivity, estrogen deficiency, and osteoporosis. J Biomech 2014; 48:855-65. [PMID: 25582356 DOI: 10.1016/j.jbiomech.2014.12.007] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2014] [Indexed: 11/26/2022]
Abstract
Adaptation of bone to mechanical stresses normally produces a bone architecture that combines a proper resistance against failure with a minimal use of material. This adaptive process is governed by mechanosensitive osteocytes that transduce the mechanical signals into chemical responses, i.e. the osteocytes release signaling molecules, which orchestrate the recruitment and activity of bone forming osteoblasts and/or bone resorbing osteoclasts. Computer models have shown that the maintenance of a mechanically-efficient bone architecture depends on the intensity and spatial distribution of the mechanical stimulus as well as on the osteocyte response. Osteoporosis is a condition characterized by a reduced bone mass and a compromized resistance of bone against mechanical loads, which has led us to hypothesize that mechanotransduction by osteocytes is altered in osteoporosis. One of the major causal factors for osteoporosis is the loss of estrogen, the major hormonal regulator of bone metabolism. Loss of estrogen may increase osteocyte-mediated activation of bone remodeling, resulting in impaired bone mass and architecture. In this review we highlight current insights on how osteocytes perceive mechanical stimuli placed on whole bones. Particular emphasis is placed on the role of estrogen in signaling pathway activation by mechanical stimuli, and on computer simulation in combination with cell biology to unravel biological processes contributing to bone strength.
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Affiliation(s)
- Jenneke Klein-Nulend
- Department of Oral Cell Biology, ACTA-University of Amsterdam and VU University Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands.
| | - René F M van Oers
- Department of Oral Cell Biology, ACTA-University of Amsterdam and VU University Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands; Department of Dental Materials Science, ACTA-University of Amsterdam and VU University Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands
| | - Astrid D Bakker
- Department of Oral Cell Biology, ACTA-University of Amsterdam and VU University Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands
| | - Rommel G Bacabac
- Department of Physics, Medical Biophysics Group, University of San Carlos, Cebu City, Philippines
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Lynch ME, Fischbach C. Biomechanical forces in the skeleton and their relevance to bone metastasis: biology and engineering considerations. Adv Drug Deliv Rev 2014; 79-80:119-34. [PMID: 25174311 DOI: 10.1016/j.addr.2014.08.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Revised: 07/30/2014] [Accepted: 08/20/2014] [Indexed: 12/17/2022]
Abstract
Bone metastasis represents the leading cause of breast cancer related-deaths. However, the effect of skeleton-associated biomechanical signals on the initiation, progression, and therapy response of breast cancer bone metastasis is largely unknown. This review seeks to highlight possible functional connections between skeletal mechanical signals and breast cancer bone metastasis and their contribution to clinical outcome. It provides an introduction to the physical and biological signals underlying bone functional adaptation and discusses the modulatory roles of mechanical loading and breast cancer metastasis in this process. Following a definition of biophysical design criteria, in vitro and in vivo approaches from the fields of bone biomechanics and tissue engineering that may be suitable to investigate breast cancer bone metastasis as a function of varied mechano-signaling will be reviewed. Finally, an outlook of future opportunities and challenges associated with this newly emerging field will be provided.
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Affiliation(s)
- Maureen E Lynch
- Department of Biomedical Engineering, Cornell University, Ithaca, USA
| | - Claudia Fischbach
- Department of Biomedical Engineering, Cornell University, Ithaca, USA; Kavli Institute at Cornell for Nanoscale Science, Cornell University, USA.
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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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Haugh MG, Vaughan TJ, McNamara LM. The role of integrin α(V)β(3) in osteocyte mechanotransduction. J Mech Behav Biomed Mater 2014; 42:67-75. [PMID: 25460927 DOI: 10.1016/j.jmbbm.2014.11.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 10/30/2014] [Accepted: 11/01/2014] [Indexed: 10/24/2022]
Abstract
Recent in vivo studies have proposed that integrin αvβ3 attachments between osteocyte cell processes and the extracellular matrix may facilitate mechanosensation in bone. However the role of these attachments in osteocyte biochemical response to mechanical stimulus has yet to be investigated. With this in mind, the objective of this study was to determine the effect of blocking integrin αvβ3 function on the biochemical response of osteocytes to mechanical stimulus. Antagonists specific to integrin subunit β3 were used to block integrin αvβ3 on MLO-Y4 mouse osteocytes. After treatment, cells were subjected to laminar oscillatory fluid flow stimulus (1 Pa, 1 Hz) for one hour. Fluorescent staining was performed to visualise cell morphology. Prostaglandin E2 (PGE2) release was assayed using an enzyme immunoassay and qRT-PCR was used to analyse the relative expression of cyclooxygenase-2 (COX-2), receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG). Our results show that blocking integrin αvβ3 disrupts osteocyte morphology, causing a reduction in spread area and process retraction. Integrin αvβ3 blocking also disrupted COX-2 expression and PGE2 release in response to fluid shear stress. Taken together, the results of this study indicate that integrin αvβ3 is essential for the maintenance of osteocyte cell processes and also for mechanosensation and mechanotransduction by osteocytes. A better understanding of this process may lead to the development of novel treatments for bone pathologies where mechanosensitivity is thought to be compromised.
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Affiliation(s)
- Matthew G Haugh
- Centre for Biomechanics Research (BMEC), Mechanical and Biomedical Engineering, National University of Ireland, Galway, Ireland; National Centre for Biomedical Engineering Sciences (NCBES), National University of Ireland, Galway, Ireland
| | - Ted J Vaughan
- Centre for Biomechanics Research (BMEC), Mechanical and Biomedical Engineering, National University of Ireland, Galway, Ireland
| | - Laoise M McNamara
- Centre for Biomechanics Research (BMEC), Mechanical and Biomedical Engineering, National University of Ireland, Galway, Ireland; National Centre for Biomedical Engineering Sciences (NCBES), National University of Ireland, Galway, Ireland.
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37
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Takano-Yamamoto T. Osteocyte function under compressive mechanical force. JAPANESE DENTAL SCIENCE REVIEW 2014. [DOI: 10.1016/j.jdsr.2013.10.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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38
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Klein-Nulend J, van Oers RFM, Bakker AD, Bacabac RG. Nitric oxide signaling in mechanical adaptation of bone. Osteoporos Int 2014; 25:1427-37. [PMID: 24322479 DOI: 10.1007/s00198-013-2590-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 11/24/2013] [Indexed: 01/27/2023]
Abstract
One of the most serious healthcare problems in the world is bone loss and fractures due to a lack of physical activity in elderly people as well as in bedridden patients or otherwise inactive youth. Crucial here are the osteocytes. Buried within our bones, these cells are believed to be the mechanosensors that stimulate bone formation in the presence of mechanical stimuli and bone resorption in the absence of such stimuli. Intercellular signaling is an important physiological phenomenon involved in maintaining homeostasis in all tissues. In bone, intercellular communication via chemical signals like NO plays a critical role in the dynamic process of bone remodeling. If bones are mechanically loaded, fluid flows through minute channels in the bone matrix, resulting in shear stress on the cell membrane that activates the osteocyte. Activated osteocytes produce signaling molecules like NO, which modulate the activity of the bone-forming osteoblasts and the bone-resorbing osteoclasts, thereby orchestrating bone adaptation to mechanical loading. In this review, we highlight current insights in the role of NO in the mechanical adaptation of bone mass and structure, with emphasis on its role in local bone gain and loss as well as in remodeling supervised by osteocytes. Since mechanical stimuli and NO production enhance bone strength and fracture resistance, these new insights may facilitate the development of novel osteoporosis treatments.
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Affiliation(s)
- J Klein-Nulend
- Department of Oral Cell Biology, ACTA-University of Amsterdam and VU University Amsterdam, MOVE Research Institute Amsterdam, Gustav Mahlerlaan 3004, 1081, LA, Amsterdam, The Netherlands,
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Altmann B, Löchner A, Swain M, Kohal RJ, Giselbrecht S, Gottwald E, Steinberg T, Tomakidi P. Differences in morphogenesis of 3D cultured primary human osteoblasts under static and microfluidic growth conditions. Biomaterials 2014; 35:3208-19. [DOI: 10.1016/j.biomaterials.2013.12.088] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 12/22/2013] [Indexed: 11/30/2022]
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40
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Shah N, Morsi Y, Manasseh R. From mechanical stimulation to biological pathways in the regulation of stem cell fate. Cell Biochem Funct 2014; 32:309-25. [PMID: 24574137 DOI: 10.1002/cbf.3027] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 11/28/2013] [Accepted: 01/07/2014] [Indexed: 12/15/2022]
Abstract
Mechanical stimuli are important in directing the fate of stem cells; the effects of mechanical stimuli reported in recent research are reviewed here. Stem cells normally undergo two fundamental processes: proliferation, in which their numbers multiply, and differentiation, in which they transform into the specialized cells needed by the adult organism. Mechanical stimuli are well known to affect both processes of proliferation and differentiation, although the complete pathways relating specific mechanical stimuli to stem cell fate remain to be elucidated. We identified two broad classes of research findings and organized them according to the type of mechanical stress (compressive, tensile or shear) of the stimulus. Firstly, mechanical stress of any type activates stretch-activated channels (SACs) on the cell membrane. Activation of SACs leads to cytoskeletal remodelling and to the expression of genes that regulate the basic growth, survival or apoptosis of the cells and thus regulates proliferation. Secondly, mechanical stress on cells that are physically attached to an extracellular matrix (ECM) initiates remodelling of cell membrane structures called integrins. This second process is highly dependent on the type of mechanical stress applied and result into various biological responses. A further process, the Wnt pathway, is also implicated: crosstalk between the integrin and Wnt pathways regulates the switch from proliferation to differentiation and finally regulates the type of differentiation. Therefore, the stem cell differentiation process involves different signalling molecules and their pathways and most likely depends upon the applied mechanical stimulation.
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Affiliation(s)
- Nirali Shah
- Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, VIC, Melbourne, Australia
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Gong X, Yang W, Wang L, Duncan RL, Pan J. Prostaglandin E2 modulates F-actin stress fiber in FSS-stimulated MC3T3-E1 cells in a PKA-dependent manner. Acta Biochim Biophys Sin (Shanghai) 2014; 46:40-7. [PMID: 24296051 DOI: 10.1093/abbs/gmt126] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The effect of prostaglandin E2 (PGE2) on bone mass has been well-established in vivo. Previous studies have showed that PGE2 increases differentiation, proliferation, and regulates cell morphology through F-actin stress fiber in statically cultured osteoblasts. However, the effect of PGE2 on osteoblasts in the presence of fluid shear stress (FSS), which could better uncover the anabolic effect of PGE2 in vivo, has yet to be examined. Here, we hypothesized that PGE2 modulates F-actin stress fiber in FSS-stimulated MC3T3-E1 osteoblastic cells through protein kinase A (PKA) pathway. Furthermore, this PGE2-induced F-actin remodeling was associated with the recovery of cellular mechanosensitivity. Our data showed that treatment with 10 nM dmPGE2 for 15 min significantly suppressed the F-actin stress fiber intensity in FSS-stimulated cells in a PKA-dependent manner. In addition, dmPGE2 treatment enhanced the cells' calcium peak magnitude and the percentage of responding cells in the second FSS stimulation, though these effects were abolished and attenuated by co-treatment with phalloidin. Our results demonstrated that 10 nM dmPGE2 was able to accelerate the 'reset' process of F-actin stress fiber to its pre-stimulated level partially through PKA pathway, and thus promoted the recovery of cellular mechanosensitivity. Our finding provided a novel cellular mechanism by which PGE2 increased bone formation as shown in vivo, suggesting that PGE2 could be a potential target for treatments of bone formation-related diseases.
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Affiliation(s)
- Xiaoyuan Gong
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, China
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Hoshi K, Kawaki H, Takahashi I, Takeshita N, Seiryu M, Murshid SA, Masuda T, Anada T, Kato R, Kitaura H, Suzuki O, Takano-Yamamoto T. Compressive force-produced CCN2 induces osteocyte apoptosis through ERK1/2 pathway. J Bone Miner Res 2014; 29:1244-57. [PMID: 24155087 DOI: 10.1002/jbmr.2115] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 09/27/2013] [Accepted: 10/08/2013] [Indexed: 11/06/2022]
Abstract
Osteocytes produce various factors that mediate the onset of bone formation and resorption and play roles in maintaining bone homeostasis and remodeling in response to mechanical stimuli. One such factor, CCN2, is thought to play a significant role in osteocyte responses to mechanical stimuli, but its function in osteocytes is not well understood. Here, we showed that CCN2 induces apoptosis in osteocytes under compressive force loading. Compressive force increased CCN2 gene expression and production, and induced apoptosis in osteocytes. Application of exogenous CCN2 protein induced apoptosis, and a neutralizing CCN2 antibody blocked loading-induced apoptosis. We further examined how CCN2 induces loaded osteocyte apoptosis. In loaded osteocytes, extracellular signal-regulated kinase 1/2 (ERK1/2) was activated, and an ERK1/2 inhibitor blocked loading-induced apoptosis. Furthermore, application of exogenous CCN2 protein caused ERK1/2 activation, and the neutralizing CCN2 antibody inhibited loading-induced ERK1/2 activation. Therefore, this study demonstrated for the first time to our knowledge that enhanced production of CCN2 in osteocytes under compressive force loading induces apoptosis through activation of ERK1/2 pathway.
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Affiliation(s)
- Kenji Hoshi
- Division of Orthodontics and Dentofacial Orthopedics, Tohoku University Graduate School of Dentistry, Sendai, Japan
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Xu H, Guan Y, Wu J, Zhang J, Duan J, An L, Shang P. Polycystin 2 is involved in the nitric oxide production in responding to oscillating fluid shear in MLO-Y4 cells. J Biomech 2013; 47:387-91. [PMID: 24268313 DOI: 10.1016/j.jbiomech.2013.11.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Revised: 10/07/2013] [Accepted: 11/06/2013] [Indexed: 02/03/2023]
Abstract
As a mechano-calcium channel, polycystin2 (PC2) play an important role in the response of renal epithelial cells to fluid flow shear stress. In bone tissue, osteocytes are well known as the main mechanosensory cells, and sensitive to fluid flow stimulus in vitro. In the study, we investigated the effects of oscillating fluid flow (OFF, 2 h, 1 Hz, 1.0 Pa) on the release of Nitric Oxide (NO) and ProstaglandinE2 (PGE2), and the role of PC2 on the release. Our findings demonstrate that PC2 expression increases after 2 h of OFF, and silencing PC2 by RNAi inhibits downstream NO production and iNOS expression, but does not affect the response of PGE2 to OFF.
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Affiliation(s)
- Huiyun Xu
- Key Laboratory for Space Biosciences & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi Xilu, Xi'an 710072, Shaanxi Province, People's Republic of China
| | - Ying Guan
- Key Laboratory for Space Biosciences & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi Xilu, Xi'an 710072, Shaanxi Province, People's Republic of China
| | - Jiawei Wu
- Key Laboratory for Space Biosciences & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi Xilu, Xi'an 710072, Shaanxi Province, People's Republic of China
| | - Jian Zhang
- Key Laboratory for Space Biosciences & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi Xilu, Xi'an 710072, Shaanxi Province, People's Republic of China
| | - Jin Duan
- Key Laboratory for Space Biosciences & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi Xilu, Xi'an 710072, Shaanxi Province, People's Republic of China
| | - Long An
- Key Laboratory for Space Biosciences & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi Xilu, Xi'an 710072, Shaanxi Province, People's Republic of China
| | - Peng Shang
- Key Laboratory for Space Biosciences & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, 127 Youyi Xilu, Xi'an 710072, Shaanxi Province, People's Republic of China.
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Li Y, Luo Y, Huang K, Xing J, Xie Z, Lin M, Yang L, Wang Y. The responses of osteoblasts to fluid shear stress depend on substrate chemistries. Arch Biochem Biophys 2013; 539:38-50. [DOI: 10.1016/j.abb.2013.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 08/21/2013] [Accepted: 09/04/2013] [Indexed: 10/26/2022]
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Li Y, Luo Y, Xie Z, Xing J, Lin M, Yang L, Wang Y, Huang K. The optimal combination of substrate chemistry with physiological fluid shear stress. Colloids Surf B Biointerfaces 2013; 112:51-60. [PMID: 23948154 DOI: 10.1016/j.colsurfb.2013.07.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 06/28/2013] [Accepted: 07/02/2013] [Indexed: 11/16/2022]
Abstract
Osteoblasts on implanted biomaterials sense both substrate chemistry and mechanical stimulus. The effects of substrate chemistry alone and mechanical stimulus alone on osteoblasts have been widely studied. This study investigates the optimal combination of substrate chemistry and 12dyn/cm(2) physiological flow shear stress (FSS) by examining their influences on primary rat osteoblasts (ROBs), including the releases of ATP, nitric oxide (NO), and prostaglandin E2 (PGE2). Self-assembled monolayers (SAMs) on glass slides with -OH, -CH3, and -NH2 were employed to provide various substrate chemistries, whereas a parallel-plate fluid flow system produced the physiological FSS. Substrate chemistry alone exerted no observable effects on the releases of ATP, NO, and PGE2. Nevertheless, when ROBs were exposed to both substrate chemistry and FSS, the ATP releases of NH2 were upregulated about 12-fold compared to substrate chemistry alone, while the ATP releases of CH3 and OH was similarly increased 7-fold at the peak. Similar trends were observed for the releases of NO and PGE2. The expressions of ATP, NO, and PGE2 followed the pattern of NH2-FSS>Glass-FSS>CH3-FSS≈OH-FSS. ROBs on NH2 produced the optimal combination of substrate chemistry with the physiological FSS. The F-actin organization and focal adhesion (FA) formation of ROBs on various SAMs without FSS were examined. NH2 produced the best results whereas CH3 and OH produced the worst ones. Inhibition of FAs and/or disruption of F-actin significantly decreased the releases of FSS-induced PGE2, NO, and/or ATP. Consequently, a mechanism was proposed that the best F-actin organization and FA formation of ROBs on NH2 lead to the optimal combination of substrate chemistry with the 12dyn/cm(2) physiological FSS. This mechanism gives guidance for the design of implanted biomaterials and bioreactors for bone tissue engineering.
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Affiliation(s)
- Yan Li
- Key Laboratory of Biorheological Science and Technology, Chongqing University, Ministry of Education, Chongqing 400030, China; Research Center of Bioinspired Materials Science and Engineering, College of Bioengineering, Chongqing University, Chongqing 400030, China
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Klein-Nulend J, Bakker AD, Bacabac RG, Vatsa A, Weinbaum S. Mechanosensation and transduction in osteocytes. Bone 2013; 54:182-90. [PMID: 23085083 DOI: 10.1016/j.bone.2012.10.013] [Citation(s) in RCA: 297] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 10/09/2012] [Accepted: 10/10/2012] [Indexed: 01/08/2023]
Abstract
The human skeleton is a miracle of engineering, combining both toughness and light weight. It does so because bones possess cellular mechanisms wherein external mechanical loads are sensed. These mechanical loads are transformed into biological signals, which ultimately direct bone formation and/or bone resorption. Osteocytes, since they are ubiquitous in the mineralized matrix, are the cells that sense mechanical loads and transduce the mechanical signals into a chemical response. The osteocytes then release signaling molecules, which orchestrate the recruitment and activity of osteoblasts or osteoclasts, resulting in the adaptation of bone mass and structure. In this review, we highlight current insights in bone adaptation to external mechanical loading, with an emphasis on how a mechanical load placed on whole bones is translated and amplified into a mechanical signal that is subsequently sensed by the osteocytes.
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Affiliation(s)
- Jenneke Klein-Nulend
- Department of Oral Cell Biology, ACTA-VU University Amsterdam, Research Institute MOVE, Gustav Mahlerlaan 3004, 1081 LA Amsterdam, The Netherlands.
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Prodanov L, Semeins C, van Loon J, te Riet J, Jansen J, Klein-Nulend J, Walboomers X. Influence of nanostructural environment and fluid flow on osteoblast-like cell behavior: a model for cell-mechanics studies. Acta Biomater 2013; 9:6653-62. [PMID: 23415750 DOI: 10.1016/j.actbio.2013.02.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 01/30/2013] [Accepted: 02/05/2013] [Indexed: 02/08/2023]
Abstract
Introducing nanoroughness on various biomaterials has been shown to profoundly effect cell-material interactions. Similarly, physical forces act on a diverse array of cells and tissues. Particularly in bone, the tissue experiences compressive or tensile forces resulting in fluid shear stress. The current study aimed to develop an experimental setup for bone cell behavior, combining a nanometrically grooved substrate (200 nm wide, 50 nm deep) mimicking the collagen fibrils of the extracellular matrix, with mechanical stimulation by pulsatile fluid flow (PFF). MC3T3-E1 osteoblast-like cells were assessed for morphology, expression of genes involved in cell attachment and osteoblastogenesis and nitric oxide (NO) release. The results showed that both nanotexture and PFF did affect cellular morphology. Cells aligned on nanotexture substrate in a direction parallel to the groove orientation. PFF at a magnitude of 0.7 Pa was sufficient to induce alignment of cells on a smooth surface in a direction perpendicular to the applied flow. When environmental cues texture and flow were interacting, PFF of 1.4 Pa applied parallel to the nanogrooves initiated significant cellular realignment. PFF increased NO synthesis 15-fold in cells attached to both smooth and nanotextured substrates. Increased collagen and alkaline phosphatase mRNA expression was observed on the nanotextured substrate, but not on the smooth substrate. Furthermore, vinculin and bone sialoprotein were up-regulated after 1 h of PFF stimulation. In conclusion, the data show that interstitial fluid forces and structural cues mimicking extracellular matrix contribute to the final bone cell morphology and behavior, which might have potential application in tissue engineering.
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48
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Hoey DA, Tormey S, Ramcharan S, O'Brien FJ, Jacobs CR. Primary cilia-mediated mechanotransduction in human mesenchymal stem cells. Stem Cells 2013; 30:2561-70. [PMID: 22969057 PMCID: PMC3533782 DOI: 10.1002/stem.1235] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Physical loading is a potent stimulus required to maintain bone homeostasis, partly through the renewal and osteogenic differentiation of mesenchymal stem cells (MSCs). However, the mechanism by which MSCs sense a biophysical force and translate that into a biochemical bone forming response (mechanotransduction) remains poorly understood. The primary cilium is a single sensory cellular extension, which has recently been shown to demonstrate a role in cellular mechanotransduction and MSC lineage commitment. In this study, we present evidence that short periods of mechanical stimulation in the form of oscillatory fluid flow (OFF) is sufficient to enhance osteogenic gene expression and proliferation of human MSCs (hMSCs). Furthermore, we demonstrate that the cilium mediates fluid flow mechanotransduction in hMSCs by maintaining OFF-induced increases in osteogenic gene expression and, surprisingly, to limit OFF-induced increases in proliferation. These data therefore demonstrate a pro-osteogenic mechanosensory role for the primary cilium, establishing a novel mechanotransduction mechanism in hMSCs. Based on these findings, the application of OFF may be a beneficial component of bioreactor-based strategies to form bone-like tissues suitable for regenerative medicine and also highlights the cilium as a potential therapeutic target for efforts to mimic loading with the aim of preventing bone loss during diseases such as osteoporosis. Furthermore, this study demonstrates a role for the cilium in controlling mechanically mediated increases in the proliferation of hMSCs, which parallels proposed models of polycystic kidney disease. Unraveling the mechanisms leading to rapid proliferation of mechanically stimulated MSCs with defective cilia could provide significant insights regarding ciliopathies and cystic diseases. Stem Cells2012;30:2561–2570
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Affiliation(s)
- David A Hoey
- Department of Biomedical Engineering, Columbia University, City of New York, New York, USA.
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Bakker AD, Zandieh-Doulabi B, Klein-Nulend J. Strontium ranelate affects signaling from mechanically-stimulated osteocytes towards osteoclasts and osteoblasts. Bone 2013; 53:112-9. [PMID: 23234812 DOI: 10.1016/j.bone.2012.11.044] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 11/28/2012] [Accepted: 11/29/2012] [Indexed: 01/28/2023]
Abstract
Strontium Ranelate (SrRan) is used to decrease the risk of bone fractures. Any factor that alters the release of paracrine signals by osteocytes in response to mechanical stimuli potentially affects bone mass and structure, and thus fracture resistance. We hypothesized that SrRan affects paracrine signaling from mechanically-stimulated osteocytes towards osteoclast-precursors and osteoblasts. MLO-Y4 osteocytes were cultured for 24h with SrRan (0.1-3mM) and either or not mechanically stimulated by pulsating fluid flow (PFF; 0.7 ± 0.3 Pa, 5 Hz) for 60 min. Nitric oxide (NO) and prostaglandin E(2) (PGE(2)) release, and expression of mechanoresponsive genes were quantified. Conditioned medium (CM) from osteocytes was added to mouse bone marrow cells for 7 days to assess osteoclastogenesis, or MC3T3-E1 osteoblasts for 4-16 days to measure osteogenic gene expression. SrRan (3mM) enhanced NO and PGE(2) release to the same extent in static osteocytes (NO: 1.6-fold; PGE(2): 2.8-fold) and PFF-stimulated osteocytes (NO: 1.3-fold; PGE(2): 2.6-fold). CM from PFF-treated osteocytes without SrRan enhanced Ki67 expression but reduced Runx2 and Ocn expression in osteoblasts. This effect on gene expression was not observed with CM obtained from osteocytes treated with the combination of PFF and 3mM SrRan. CM from PFF-treated osteocytes inhibited osteoclastogenesis by 1.9-fold. The combination of PFF and 3mM SrRan reduced osteocyte-stimulated osteoclastogenesis even more strongly (4.3-fold). In conclusion, SrRan affects paracrine signaling between mechanically-stimulated MLO-Y4 osteocytes and both osteoblasts and osteoclast precursors. The positive effects of SrRan on bone fracture resistance may thus be partly explained by altered paracrine signaling by osteocytes.
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Affiliation(s)
- Astrid D Bakker
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam, University of Amsterdam.
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50
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Lu XL, Huo B, Park M, Guo XE. Calcium response in osteocytic networks under steady and oscillatory fluid flow. Bone 2012; 51:466-73. [PMID: 22750013 PMCID: PMC3412915 DOI: 10.1016/j.bone.2012.05.021] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 05/04/2012] [Accepted: 05/05/2012] [Indexed: 02/05/2023]
Abstract
The fluid flow in the lacunar-canalicular system of bone is an essential mechanical stimulation on the osteocyte networks. Due to the complexity of human physical activities, the fluid shear stress on osteocyte bodies and processes consists of both steady and oscillatory components. In this study, we investigated and compared the intracellular calcium ([Ca(2+)](i)) responses of osteocytic networks under steady and oscillatory fluid flows. An in vitro osteocytic network was built with MLO-Y4 osteocyte-like cells using micro-patterning techniques to simulate the in vivo orderly organization of osteocyte networks. Sinusoidal oscillating fluid flow or unidirectional steady flow was applied on the cell surface with 2Pa peak shear stress. It was found that the osteocytic networks were significantly more responsive to steady flow than to oscillatory flow. The osteocytes can release more calcium peaks with higher magnitudes at a faster speed under steady flow stimulation. The [Ca(2+)](i) signaling transients under the steady and oscillatory flows have significantly different spatiotemporal characters, but a similar responsive percentage of cells. Further signaling pathway studies using inhibitors showed that endoplasmic reticulum (ER) calcium store, extracellular calcium source, ATP, PGE(2) and NO related pathways play similar roles in the [Ca(2+)](i) signaling of osteocytes under either steady or oscillating flow. The spatiotemporal characteristics of [Ca(2+)](i) transients under oscillating fluid flow are affected more profoundly by pharmacological treatments than under the steady flow. Our findings support the hypothesis that the [Ca(2+)](i) responses of osteocytic networks are significantly dependent on the profiles of fluid flow.
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Affiliation(s)
- X. Lucas Lu
- Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY 10027
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716
| | - Bo Huo
- Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY 10027
- Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Miri Park
- Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY 10027
- Department of Mechanical Engineering, University of Delaware, Newark, DE 19716
| | - X. Edward Guo
- Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY 10027
- Address correspondence to: Professor X. Edward Guo, Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, Telephone: (212) 854-6196, Fax: (212) 854-8725,
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