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Wang Z, Zhang X, Cheng X, Ren T, Xu W, Li J, Wang H, Zhang J. Inflammation produced by senescent osteocytes mediates age-related bone loss. Front Immunol 2023; 14:1114006. [PMID: 36814916 PMCID: PMC9940315 DOI: 10.3389/fimmu.2023.1114006] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 01/11/2023] [Indexed: 02/08/2023] Open
Abstract
Purpose The molecular mechanisms of age-related bone loss are unclear and without valid drugs yet. The aims of this study were to explore the molecular changes that occur in bone tissue during age-related bone loss, to further clarify the changes in function, and to predict potential therapeutic drugs. Methods We collected bone tissues from children, middle-aged individuals, and elderly people for protein sequencing and compared the three groups of proteins pairwise, and the differentially expressed proteins (DEPs) in each group were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). K-means cluster analysis was then used to screen out proteins that continuously increased/decreased with age. Canonical signaling pathways that were activated or inhibited in bone tissue along with increasing age were identified by Ingenuity Pathway Analysis (IPA). Prediction of potential drugs was performed using the Connectivity Map (CMap). Finally, DEPs from sequencing were verified by Western blot, and the drug treatment effect was verified by quantitative real-time PCR. Results The GO and KEGG analyses show that the DEPs were associated with inflammation and bone formation with aging, and the IPA analysis shows that pathways such as IL-8 signaling and acute-phase response signaling were activated, while glycolysis I and EIF2 signaling were inhibited. A total of nine potential drugs were predicted, with rapamycin ranking the highest. In cellular experiments, rapamycin reduced the senescence phenotype produced by the H2O2-stimulated osteocyte-like cell MLO-Y4. Conclusion With age, inflammatory pathways are activated in bone tissue, and signals that promote bone formation are inhibited. This study contributes to the understanding of the molecular changes that occur in bone tissue during age-related bone loss and provides evidence that rapamycin is a drug of potential clinical value for this disease. The therapeutic effects of the drug are to be further studied in animals.
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Affiliation(s)
- Zixuan Wang
- Department of Emergency Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaofei Zhang
- Center for Translational Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xing Cheng
- Health Care Management Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Tianxing Ren
- Department of Emergency Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Weihua Xu
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jin Li
- Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hui Wang
- Department of Medical Genetics, Basic School of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China,*Correspondence: Jinxiang Zhang, ; Hui Wang,
| | - Jinxiang Zhang
- Department of Emergency Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China,*Correspondence: Jinxiang Zhang, ; Hui Wang,
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2
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Hua R, Gu S, Jiang JX. Connexin 43 Hemichannels Regulate Osteoblast to Osteocyte Differentiation. Front Cell Dev Biol 2022; 10:892229. [PMID: 35693933 PMCID: PMC9184820 DOI: 10.3389/fcell.2022.892229] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/18/2022] [Indexed: 11/13/2022] Open
Abstract
Connexin 43 (Cx43) is the predominant connexin subtype expressed in osteocytes. Osteocytes, accounting for 90%–95% of total bone cells, function as orchestrators coordinating balanced activity between bone-resorbing osteoclasts and bone-forming osteoblasts. In this study, two newly developed osteocytic cell lines, OCY454 and IDG-SW3, were used to determine the role of Cx43 gap junctions and hemichannels (HCs) in the regulation of osteoblast to osteocyte differentiation. We found that the Cx43 level was substantially increased during the differentiation of IDG-SW3 cells and is also much higher than that of OCY454 cells. We knocked down Cx43 expression using the lentiviral CRISPR/Cas9 approach and inhibition of Cx43 HCs using Cx43 (E2) antibody in IDG-SW3 cells. Cx43 knockdown (KD) or Cx43 HC inhibition decreased gene expression for osteoblast and osteocyte markers, including alkaline phosphatase, type I collagen, dentin matrix protein 1, sclerostin, and fibroblast growth factor 23, whereas increasing the osteoclastogenesis indicator and the receptor activator of nuclear factor kappa-B ligand (RANKL)/osteoprotegerin (OPG) ratio at early and late differentiation stages. Moreover, mineralization was remarkably attenuated in differentiated Cx43-deficient IDG-SW3 cells compared to ROSA26 control. The conditioned medium collected from fully differentiated IDG-SW3 cells with Cx43 KD promoted osteoclastogenesis of RAW264.7 osteoclast precursors. Our results demonstrated that Cx43 HCs play critical roles in osteoblast to osteocyte differentiation process and regulate osteoclast differentiation via secreted factors.
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3
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Sutthavas P, Tahmasebi Birgani Z, Habibovic P, Rijt S. Calcium Phosphate-Coated and Strontium-Incorporated Mesoporous Silica Nanoparticles Can Effectively Induce Osteogenic Stem Cell Differentiation. Adv Healthc Mater 2022; 11:e2101588. [PMID: 34751004 DOI: 10.1002/adhm.202101588] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 11/01/2021] [Indexed: 01/16/2023]
Abstract
Ceramic (nano)materials are promising materials for bone regeneration applications. The addition of bioinorganics such as strontium (Sr) and zinc (Zn) is a popular approach to further improve their biological performance. However, control over ion delivery is important to prevent off-target effects. Mesoporous silica nanoparticles (MSNs) are popular nanomaterials that can be designed to incorporate and controllably deliver multiple ions to steer specific regenerative processes. In this work, MSNs loaded with Sr (MSNSr ) and surface coated with a pH-sensitive calcium phosphate (MSNSr -CaP) or calcium phosphate zinc layer (MSNSr -CaZnP) are developed. The ability of the MSNs to promote osteogenesis in human mesenchymal stromal cells (hMSCs) under basic cell culture conditions is explored and compared to ion administration directly to the cell culture media. Here, it is shown that MSN-CaPs can effectively induce alkaline phosphatase (ALP) levels and osteogenic gene expression in the absence of other osteogenic stimulants, where an improved effect is observed for MSNs surface coated with multiple ions. Moreover, comparatively lower ion doses are needed when using MSNs as delivery vehicles compared to direct ion administration in the medium. In summary, the MSNs developed here represent promising vehicles to deliver (multiple) bioinorganics and promote hMSC osteogenesis in basic conditions.
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Affiliation(s)
- Pichaporn Sutthavas
- Department of Instructive Biomaterials Engineering MERLN Institute for Technology‐Inspired Regenerative Medicine Maastricht University P.O. Box 616 Maastricht 6200 MD the Netherlands
| | - Zeinab Tahmasebi Birgani
- Department of Instructive Biomaterials Engineering MERLN Institute for Technology‐Inspired Regenerative Medicine Maastricht University P.O. Box 616 Maastricht 6200 MD the Netherlands
| | - Pamela Habibovic
- Department of Instructive Biomaterials Engineering MERLN Institute for Technology‐Inspired Regenerative Medicine Maastricht University P.O. Box 616 Maastricht 6200 MD the Netherlands
| | - Sabine Rijt
- Department of Instructive Biomaterials Engineering MERLN Institute for Technology‐Inspired Regenerative Medicine Maastricht University P.O. Box 616 Maastricht 6200 MD the Netherlands
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4
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Schminke B, Kauffmann P, Schubert A, Altherr M, Gelis T, Miosge N. SMURF1 and SMURF2 in Progenitor Cells from Articular Cartilage and Meniscus during Late-Stage Osteoarthritis. Cartilage 2021; 13:117S-128S. [PMID: 33090007 PMCID: PMC8721605 DOI: 10.1177/1947603520967069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVE The aim of this study was to investigate the roles of SMURF1 and SMURF2 in progenitor cells from the human knee in late-stage osteoarthritis (OA). DESIGN We applied immunohistochemistry, immunocytochemistry, RNAi, lentiviral transfection, and Western blot analysis. We obtained chondrogenic progenitor cells (CPCs) from the articular cartilage and meniscus progenitor cells (MPCs) from the nonvascularized part of the meniscus. RESULTS SMURF1 and SMURF2 appeared in both osteoarthritic tissues. CPCs and MPCs exhibited comparable amounts of these proteins, which influence the balance between RUNX2 and SOX9. The overexpression of SMURF1 reduced the levels of RUNX2, SOX9, and TGFBR1. The overexpression of SMURF2 also reduced the levels of RUNX2 and TGFBR1, while SOX9 levels were not affected. The knockdown of SMURF1 had no effect on RUNX2, SOX9, or TGFBR1. The knockdown of SMURF2 enhanced RUNX2 and SOX9 levels in CPCs. The respective protein levels in MPCs were not affected. CONCLUSIONS This study shows that SMURF1 and SMURF2 are regulatory players for the expression of the major regulator transcription factors RUNX2 and SOX9 in CPCs and MPCs. Our novel findings may help elucidate new treatment strategies for cartilage regeneration.
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Affiliation(s)
- Boris Schminke
- Department of Oral and Maxillofacial
Surgery, University Medical Center Goettingen, Göttingen, Germany,Oral Biology and Tissue Regeneration
Work Group, University Medical Center Goettingen, Göttingen, Germany
| | - Philipp Kauffmann
- Department of Oral and Maxillofacial
Surgery, University Medical Center Goettingen, Göttingen, Germany
| | - Andrea Schubert
- Oral Biology and Tissue Regeneration
Work Group, University Medical Center Goettingen, Göttingen, Germany
| | - Manuel Altherr
- Oral Biology and Tissue Regeneration
Work Group, University Medical Center Goettingen, Göttingen, Germany
| | - Thomas Gelis
- Oral Biology and Tissue Regeneration
Work Group, University Medical Center Goettingen, Göttingen, Germany
| | - Nicolai Miosge
- Oral Biology and Tissue Regeneration
Work Group, University Medical Center Goettingen, Göttingen, Germany,Nicolai Miosge, Oral Biology and Tissue
Regeneration Work Group, University Medical Center Göttingen,
Robert-Koch-Strasse 40, Göttingen, 37075, Germany.
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5
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Osteocytes as main responders to low-intensity pulsed ultrasound treatment during fracture healing. Sci Rep 2021; 11:10298. [PMID: 33986415 PMCID: PMC8119462 DOI: 10.1038/s41598-021-89672-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/29/2021] [Indexed: 12/11/2022] Open
Abstract
Ultrasound stimulation is a type of mechanical stress, and low-intensity pulsed ultrasound (LIPUS) devices have been used clinically to promote fracture healing. However, it remains unclear which skeletal cells, in particular osteocytes or osteoblasts, primarily respond to LIPUS stimulation and how they contribute to fracture healing. To examine this, we utilized medaka, whose bone lacks osteocytes, and zebrafish, whose bone has osteocytes, as in vivo models. Fracture healing was accelerated by ultrasound stimulation in zebrafish, but not in medaka. To examine the molecular events induced by LIPUS stimulation in osteocytes, we performed RNA sequencing of a murine osteocytic cell line exposed to LIPUS. 179 genes reacted to LIPUS stimulation, and functional cluster analysis identified among them several molecular signatures related to immunity, secretion, and transcription. Notably, most of the isolated transcription-related genes were also modulated by LIPUS in vivo in zebrafish. However, expression levels of early growth response protein 1 and 2 (Egr1, 2), JunB, forkhead box Q1 (FoxQ1), and nuclear factor of activated T cells c1 (NFATc1) were not altered by LIPUS in medaka, suggesting that these genes are key transcriptional regulators of LIPUS-dependent fracture healing via osteocytes. We therefore show that bone-embedded osteocytes are necessary for LIPUS-induced promotion of fracture healing via transcriptional control of target genes, which presumably activates neighboring cells involved in fracture healing processes.
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6
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Wang Z, Weng Y, Ishihara Y, Odagaki N, Ei Hsu Hlaing E, Izawa T, Okamura H, Kamioka H. Loading history changes the morphology and compressive force-induced expression of receptor activator of nuclear factor kappa B ligand/osteoprotegerin in MLO-Y4 osteocytes. PeerJ 2020; 8:e10244. [PMID: 33240612 PMCID: PMC7659647 DOI: 10.7717/peerj.10244] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 10/05/2020] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND In this study, we investigated the effect of the mechanical loading history on the expression of receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) in MLO-Y4 osteocyte-like cells. METHODS Three hours after MLO-Y4 osteocytes were seeded, a continuous compressive force (CCF) of 31 dynes/cm2 with or without additional CCF (32 dynes/cm2) was loaded onto the osteocytes. After 36 h, the additional CCF (loading history) was removed for a recovery period of 10 h. The expression of RANKL, OPG, RANKL/OPG ratio, cell numbers, viability and morphology were time-dependently examined at 0, 3, 6 and 10 h. Then, the same additional CCF was applied again for 1 h to all osteocytes with or without the gap junction inhibitor to examine the expression of RANKL, OPG, the RANKL/OPG ratio and other genes that essential to characterize the phenotype of MLO-Y4 cells. Fluorescence recovery after photobleaching technique was also applied to test the differences of gap-junctional intercellular communications (GJIC) among MLO-Y4 cells. RESULTS The expression of RANKL and OPG by MLO-Y4 osteocytes without a loading history was dramatically decreased and increased, respectively, in response to the 1-h loading of additional weight. However, the expression of RANKL, OPG and the RANKL/OPG ratio were maintained at the same level as in the control group in the MLO-Y4 osteocytes with a loading history but without gap junction inhibitor treatment. Treatment of loading history significantly changed the capacity of GJIC and protein expression of connexin 43 (Cx43) but not the mRNA expression of Cx43. No significant difference was observed in the cell number or viability between the MLO-Y4 osteocyte-like cells with and without a loading history or among different time checkpoints during the recovery period. The cell morphology showed significant changes and was correlated with the expression of OPG, Gja1 and Dmp1 during the recovery period. CONCLUSION Our findings indicated that the compressive force-induced changes in the RANKL/OPG expression could be habituated within at least 11 h by 36-h CCF exposure. GJIC and cell morphology may play roles in response to loading history in MLO-Y4 osteocyte-like cells.
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Affiliation(s)
- Ziyi Wang
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
- Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Yao Weng
- Department of Oral Morphology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Yoshihito Ishihara
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Naoya Odagaki
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Ei Ei Hsu Hlaing
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Takashi Izawa
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Hirohiko Okamura
- Department of Oral Morphology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Hiroshi Kamioka
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
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7
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Wang K, Le L, Chun BM, Tiede-Lewis LM, Shiflett LA, Prideaux M, Campos RS, Veno PA, Xie Y, Dusevich V, Bonewald LF, Dallas SL. A Novel Osteogenic Cell Line That Differentiates Into GFP-Tagged Osteocytes and Forms Mineral With a Bone-Like Lacunocanalicular Structure. J Bone Miner Res 2019; 34:979-995. [PMID: 30882939 PMCID: PMC7350928 DOI: 10.1002/jbmr.3720] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 02/15/2019] [Accepted: 02/22/2019] [Indexed: 01/20/2023]
Abstract
Osteocytes, the most abundant cells in bone, were once thought to be inactive, but are now known to have multifunctional roles in bone, including in mechanotransduction, regulation of osteoblast and osteoclast function and phosphate homeostasis. Because osteocytes are embedded in a mineralized matrix and are challenging to study, there is a need for new tools and cell models to understand their biology. We have generated two clonal osteogenic cell lines, OmGFP66 and OmGFP10, by immortalization of primary bone cells from mice expressing a membrane-targeted GFP driven by the Dmp1-promoter. One of these clones, OmGFP66, has unique properties compared with previous osteogenic and osteocyte cell models and forms 3-dimensional mineralized bone-like structures, containing highly dendritic GFP-positive osteocytes, embedded in clearly defined lacunae. Confocal and electron microscopy showed that structurally and morphologically, these bone-like structures resemble bone in vivo, even mimicking the lacunocanalicular ultrastructure and 3D spacing of in vivo osteocytes. In osteogenic conditions, OmGFP66 cells express alkaline phosphatase (ALP), produce a mineralized type I collagen matrix, and constitutively express the early osteocyte marker, E11/gp38. With differentiation they express osteocyte markers, Dmp1, Phex, Mepe, Fgf23, and the mature osteocyte marker, Sost. They also express RankL, Opg, and Hif1α, and show expected osteocyte responses to PTH, including downregulation of Sost, Dmp1, and Opg and upregulation of RankL and E11/gp38. Live cell imaging revealed the dynamic process by which OmGFP66 bone-like structures form, the motile properties of embedding osteocytes and the integration of osteocyte differentiation with mineralization. The OmGFP10 clone showed an osteocyte gene expression profile similar to OmGFP66, but formed less organized bone nodule-like mineral, similar to other osteogenic cell models. Not only do these cell lines provide useful new tools for mechanistic and dynamic studies of osteocyte differentiation, function, and biomineralization, but OmGFP66 cells have the unique property of modeling osteocytes in their natural bone microenvironment. © 2019 American Society for Bone and Mineral Research.
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Affiliation(s)
- Kun Wang
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, Kansas City, MO, USA
| | - Lisa Le
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, Kansas City, MO, USA
| | - Brad M Chun
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, Kansas City, MO, USA
| | - LeAnn M Tiede-Lewis
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, Kansas City, MO, USA
| | - Lora A Shiflett
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, Kansas City, MO, USA
| | - Matthew Prideaux
- Department of Anatomy and Cell Biology, School of Medicine, Indiana University, Indianapolis, IN, USA
| | - Richard S Campos
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, Kansas City, MO, USA
| | - Patricia A Veno
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, Kansas City, MO, USA
| | - Yixia Xie
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, Kansas City, MO, USA
| | - Vladimir Dusevich
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, Kansas City, MO, USA
| | - Lynda F Bonewald
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, Kansas City, MO, USA.,Department of Anatomy and Cell Biology, School of Medicine, Indiana University, Indianapolis, IN, USA.,Department of Orthopaedic Surgery, Indiana University, Indianapolis, IN, USA
| | - Sarah L Dallas
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri, Kansas City, Kansas City, MO, USA
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8
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Mei X, Middleton K, Shim D, Wan Q, Xu L, Ma YHV, Devadas D, Walji N, Wang L, Young EWK, You L. Microfluidic platform for studying osteocyte mechanoregulation of breast cancer bone metastasis. Integr Biol (Camb) 2019; 11:119-129. [DOI: 10.1093/intbio/zyz008] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 01/27/2019] [Accepted: 05/02/2019] [Indexed: 11/12/2022]
Abstract
AbstractBone metastasis is a common, yet serious, complication of breast cancer. Breast cancer cells that extravasate from blood vessels to the bone devastate bone quality by interacting with bone cells and disrupting the bone remodeling balance. Although exercise is often suggested as a cancer intervention strategy and mechanical loading during exercise is known to regulate bone remodeling, its role in preventing bone metastasis remains unknown. We developed a novel in vitro microfluidic tissue model to investigate the role of osteocytes in the mechanical regulation of breast cancer bone metastasis. Metastatic MDA-MB-231 breast cancer cells were cultured inside a 3D microfluidic lumen lined with human umbilical vein endothelial cells (HUVECs), which is adjacent to a channel seeded with osteocyte-like MLO-Y4 cells. Physiologically relevant oscillatory fluid flow (OFF) (1 Pa, 1 Hz) was applied to mechanically stimulate the osteocytes. Hydrogel-filled side channels in-between the two channels allowed real-time, bi-directional cellular signaling and cancer cell extravasation over 3 days. The applied OFF was capable of inducing intracellular calcium responses in osteocytes (82.3% cells responding with a 3.71 fold increase average magnitude). Both extravasation distance and percentage of extravasated side-channels were significantly reduced with mechanically stimulated osteocytes (32.4% and 53.5% of control, respectively) compared to static osteocytes (102.1% and 107.3% of control, respectively). This is the first microfluidic device that has successfully integrated stimulatory bone fluid flow, and demonstrated that mechanically stimulated osteocytes reduced breast cancer extravasation. Future work with this platform will determine the specific mechanisms involved in osteocyte mechanoregulation of breast cancer bone metastasis, as well as other types of cancer metastasis and diseases.
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Affiliation(s)
- Xueting Mei
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Kevin Middleton
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Dongsub Shim
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | - Qianqian Wan
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | - Liangcheng Xu
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Yu-Heng Vivian Ma
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Deepika Devadas
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | - Noosheen Walji
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | - Liyun Wang
- Department of Mechanical Engineering, University of Delaware
| | - Edmond W K Young
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Lidan You
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
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9
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Shiraki M, Xu X, Iovanna JL, Kukita T, Hirata H, Kamohara A, Kubota Y, Miyamoto H, Mawatari M, Kukita A. Deficiency of stress-associated gene Nupr1 increases bone volume by attenuating differentiation of osteoclasts and enhancing differentiation of osteoblasts. FASEB J 2019; 33:8836-8852. [PMID: 31067083 DOI: 10.1096/fj.201802322rr] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Nuclear protein 1 (NUPR1) is a multifunctional stress-induced protein involved in regulating tumorigenesis, apoptosis, and autophagy. Bone homeostasis is maintained by bone-resorbing osteoclasts and bone-forming osteoblasts and osteocytes. We aimed to determine the role of NUPR1 in bone metabolism. Using microcomputed tomography, we found that mice lacking Nupr1 exhibited increased bone volume. Histologic analysis showed that Nupr1 deficiency decreased osteoclast numbers but increased osteoblast numbers and osteoid formation. In vitro culture of bone marrow macrophages showed that receptor activator of NF-κB ligand-induced osteoclastogenesis was down-regulated in Nupr1-deficient mice. In contrast, primary osteoblasts from Nupr1-deficient mice revealed that proliferation of osteoblasts and expression of bone matrix proteins were markedly enhanced. In addition, expression of autophagy-related genes, formation of autophagosomes, and cell survival were up-regulated in Nupr1-deficient osteoblasts. In contract, deletion of Nupr1 reduced the formation of osteocyte cellular projection, which is an indicator of mature osteocytes. Importantly, we found that the expression of sclerostin (Sost), an inhibitor of bone formation, was down-regulated in the osteoblasts and osteocytes of Nupr1-deficient mice. Conversely, Nupr1 overexpression enhanced Sost expression in primary osteoblasts. Collectively, these results indicate that Nupr1 deficiency increases bone volume by attenuating production of Sost and osteoclastogenesis and enhancing differentiation of osteoblasts.-Shiraki, M., Xu, X., Iovanna, J. L., Kukita, T., Hirata, H., Kamohara, A., Kubota, Y., Miyamoto, H., Mawatari, M., Kukita, A. Deficiency of stress-associated gene Nupr1 increases bone volume by attenuating differentiation of osteoclasts and enhancing differentiation of osteoblasts.
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Affiliation(s)
- Makoto Shiraki
- Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga, Japan.,Department of Orthopedic Surgery, Faculty of Medicine, Saga University, Saga, Japan
| | - Xianghe Xu
- Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga, Japan.,Department of Molecular Cell Biology and Oral Anatomy, Kyushu University, Fukuoka, Japan
| | - Juan L Iovanna
- Centre de Recherche en Cancérologie de Marseille, INSERM U 1068, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 7258, Aix-Marseille Université and Institut Paoli-Calmettes, Parc Scientifique et Technologique de Luminy, Marseille, France; and
| | - Toshio Kukita
- Department of Molecular Cell Biology and Oral Anatomy, Kyushu University, Fukuoka, Japan
| | - Hirohito Hirata
- Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga, Japan.,Department of Orthopedic Surgery, Faculty of Medicine, Saga University, Saga, Japan
| | - Asana Kamohara
- Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga, Japan
| | - Yasushi Kubota
- Division of Hematology, Respiratory Medicine, and Oncology, Department of Internal Medicine, Faculty of Medicine, Saga University, Saga, Japan
| | - Hiroshi Miyamoto
- Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga, Japan
| | - Masaaki Mawatari
- Department of Orthopedic Surgery, Faculty of Medicine, Saga University, Saga, Japan
| | - Akiko Kukita
- Department of Pathology and Microbiology, Faculty of Medicine, Saga University, Saga, Japan
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10
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Xiao X, Xu Y, Wu Q. Thiazide diuretic usage and risk of fracture: a meta-analysis of cohort studies. Osteoporos Int 2018; 29:1515-1524. [PMID: 29574519 DOI: 10.1007/s00198-018-4486-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 03/12/2018] [Indexed: 11/29/2022]
Abstract
UNLABELLED Inconsistent findings in regard to association between thiazide diuretic use and the risk of fracture have been reported during the past decade. This updated meta-analysis, which pooled data from 11 qualified prospective designed studies, found that thiazides have a significant protective effect on fracture risk. INTRODUCTION An updated comprehensive meta-analysis examine the association between thiazide diuretic use and therisk of fracture is needed. METHODS Cohort studies regarding thiazide diuretic exposure and the risk of fracture, published from inception to May 1 2017, were identified through MEDLINE, EMBASE, SCOPUS, and the Cochrane Database of Systematic Reviews. The literature search, study selection, study appraisal, and data extraction were pre-defined in the protocol and were independently conducted by two investigators. Due to the heterogeneity of the original studies, a random effects model was used to pool the confounder-adjusted relative risk (RR). RESULTS Eleven eligible cohort studies involving 2,193,160 participants were included for analysis. Overall, thiazide diuretic users, as compared with non-users, had a significant 14% reduction in the risk of all fractures (relative risk [RR], 0.86; 95% confidence interval [CI], 0.80-0.93; p = 0.009) and an 18% reduction in the risk of hip fracture (RR, 0.82; 95%CI, 0.80-0.93; p = 0.009). However, the effect size associated with thiazide use became slightly weaker when the analysis was limited to only high-quality original studies (quality score > 8) (RR, 0.89; 95%CI, 0.80-0.99; p = 0.005), studies with a larger sample size (> 10,000) (RR, 0.90; 95%CI, 0.80-1.00; p = 0.002), and studies published after 2007 (RR, 0.92; 95%CI, 0.82-1.02; p = 0.001). CONCLUSION Our findings indicate that thiazide diuretic use may convey a decreased risk of fracture and as such, the protective effect of this class of medicine should be considered when prescribing thiazide diuretics in clinical practice.
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Affiliation(s)
- X Xiao
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV, 89154-4009, USA
- Department of Environmental and Occupational Health, School of Community Health Sciences, University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV, 89154-4009, USA
| | - Y Xu
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV, 89154-4009, USA
- Department of Environmental and Occupational Health, School of Community Health Sciences, University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV, 89154-4009, USA
| | - Q Wu
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV, 89154-4009, USA.
- Department of Environmental and Occupational Health, School of Community Health Sciences, University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV, 89154-4009, USA.
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11
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Fahlgren A, Bratengeier C, Semeins CM, Klein-Nulend J, Bakker AD. Supraphysiological loading induces osteocyte-mediated osteoclastogenesis in a novel in vitro model for bone implant loosening. J Orthop Res 2018; 36:1425-1434. [PMID: 29068483 DOI: 10.1002/jor.23780] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 10/13/2017] [Indexed: 02/04/2023]
Abstract
We aimed to develop an in vitro model for bone implant loosening, allowing analysis of biophysical and biological parameters contributing to mechanical instability-induced osteoclast differentiation and peri-implant bone loss. MLO-Y4-osteocytes were mechanically stimulated for 1 h by fluid shear stress using regimes simulating: (i) supraphysiological loading in the peri-prosthetic interface (2.9 ± 2.9 Pa, 1 Hz, square wave); (ii) physiologic loading in the cortical bone (0.7 ± 0.7 Pa, 5 Hz, sinusoidal wave); and (iii) stress shielding. Cellular morphological parameters, membrane-bound RANKL expression, gene expression influencing osteoclast differentiation, nitric oxide release and caspase 3/7-activity were determined. Either Mouse bone marrow cells were cultured on top of loaded osteocytes or osteocyte-conditioned medium was added to bone marrow cells. Osteoclast differentiation was assessed after 6 days. We found that osteocytes subjected to supraphysiological loading showed similar morphology and caspase 3/7-activity compared to simulated physiological loading or stress shielding. Supraphysiological stimulation of osteocytes enhanced osteoclast differentiation by 1.9-fold compared to physiological loading when cell-to-cell contact was permitted. In addition, it enhanced the number of osteoclasts using conditioned medium by 1.7-fold, membrane-bound RANKL by 3.3-fold, and nitric oxide production by 3.2-fold. The stimulatory effect of supraphysiological loading on membrane-bound RANKL and nitric oxide production was higher than that achieved by stress shielding. In conclusion, the in vitro model developed recapitulated the catabolic biological situation in the peri-prosthetic interface during instability that is associated with osteoclast differentiation and enhanced RANKL expression. The model thus provides a platform for pre-clinical testing of pharmacological interventions with potential to stop instability-induced bone implant loosening. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1425-1434, 2018.
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Affiliation(s)
- Anna Fahlgren
- Department of Clinical and Experimental Medicine, Division of Cell Biology, Linköping University, Linköping, Sweden
| | - Cornelia Bratengeier
- Department of Clinical and Experimental Medicine, Division of Cell Biology, Linköping University, Linköping, Sweden
| | - Cornelis M Semeins
- Department of Oral Cell Biology, ACTA-University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Jenneke Klein-Nulend
- Department of Oral Cell Biology, ACTA-University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Astrid D Bakker
- Department of Oral Cell Biology, ACTA-University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
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12
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Sun Q, Choudhary S, Mannion C, Kissin Y, Zilberberg J, Lee WY. Ex vivo replication of phenotypic functions of osteocytes through biomimetic 3D bone tissue construction. Bone 2018; 106:148-155. [PMID: 29066313 PMCID: PMC5694355 DOI: 10.1016/j.bone.2017.10.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 10/16/2017] [Accepted: 10/20/2017] [Indexed: 12/11/2022]
Abstract
Osteocytes, residing as 3-dimensionally (3D) networked cells in bone, are well known to regulate bone and mineral homeostasis and have been recently implicated to interact with cancer cells to influence the progression of bone metastases. In this study, a bone tissue consisting of 3D-networked primary human osteocytes and MLO-A5 cells was constructed using: (1) the biomimetic close-packed assembly of 20-25μm microbeads with primary cells isolated from human bone samples and MLO-A5 cells and (2) subsequent perfusion culture in a microfluidic device. With this 3D tissue construction approach, we replicated ex vivo, for the first time, the mechanotransduction function of human primary osteocytes and MLO-A5 cells by correlating the effects of cyclic compression on down-regulated SOST and DKK1 expressions. Also, as an example of using our ex vivo model to evaluate therapeutic agents, we confirmed previously reported findings that parathyroid hormone (PTH) decreases SOST and increases the ratio of RANKL and OPG. In comparison to other in vitro models, our ex vivo model: (1) replicates the cell density, phenotype, and functions of primary human osteocytes and MLO-A5 cells and (2) thus provides a clinically relevant means of studying bone diseases and metastases.
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Affiliation(s)
- Qiaoling Sun
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology, Hoboken, NJ, USA
| | - Saba Choudhary
- Department of Biomedical Engineering, Chemistry and Biological Sciences, Stevens Institute of Technology, Hoboken, NJ, USA
| | - Ciaran Mannion
- Department of Pathology, Hackensack University Medical Center, Hackensack, NJ, USA
| | - Yair Kissin
- Department of Orthopeidc Surgery, Hackensack University Medical Center, Hackensack, NJ, USA
| | - Jenny Zilberberg
- Department of Biomedical Research, Hackensack University Medical Center, Hackensack, NJ, USA
| | - Woo Y Lee
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology, Hoboken, NJ, USA.
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13
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Shi C, Uda Y, Dedic C, Azab E, Sun N, Hussein AI, Petty CA, Fulzele K, Mitterberger-Vogt MC, Zwerschke W, Pereira R, Wang K, Pajevic PD. Carbonic anhydrase III protects osteocytes from oxidative stress. FASEB J 2017; 32:440-452. [PMID: 28928248 DOI: 10.1096/fj.201700485rr] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 09/05/2017] [Indexed: 12/26/2022]
Abstract
Osteocytes are master orchestrators of bone remodeling; they control osteoblast and osteoclast activities both directly via cell-to-cell communication and indirectly via secreted factors, and they are the main postnatal source of sclerostin and RANKL (receptor activator of NF-kB ligand), two regulators of osteoblast and osteoclast function. Despite progress in understanding osteocyte biology and function, much remains to be elucidated. Recently developed osteocytic cell lines-together with new genome editing tools-has allowed a closer look at the biology and molecular makeup of these cells. By using single-cell cloning, we identified genes that are associated with high Sost/sclerostin expression and analyzed their regulation and function. Unbiased transcriptome analysis of high- vs. low-Sost/sclerostin-expressing cells identified known and novel genes. Dmp1 (dentin matrix protein 1), Dkk1 (Dickkopf WNT signaling pathway inhibitor 1), and Phex were among the most up-regulated known genes, whereas Srpx2, Cd200, and carbonic anhydrase III (CAIII) were identified as novel markers of differentiated osteocytes. Aspn, Enpp2, Robo2, Nov, and Serpina3g were among the transcripts that were most significantly suppressed in high-Sost cells. Considering that CAII was recently identified as being regulated by Sost/sclerostin and capable of controlling mineral homeostasis, we focused our attention on CAIII. Here, we report that CAIII is highly expressed in osteocytes, is regulated by parathyroid hormone both in vitro and in vivo, and protects osteocytes from oxidative stress.-Shi, C., Uda, Y., Dedic, C., Azab, E., Sun, N., Hussein, A. I., Petty, C. A., Fulzele, K., Mitterberger-Vogt, M. C., Zwerschke, W., Pereira, R., Wang, K., Divieti Pajevic, P. Carbonic anhydrase III protects osteocytes from oxidative stress.
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Affiliation(s)
- Chao Shi
- Department of Orthopaedics, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.,Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Yuhei Uda
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Christopher Dedic
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Ehab Azab
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Ningyuan Sun
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Amira I Hussein
- Department of Orthopedics, School of Medicine, Boston University, Boston, Massachusetts, USA
| | - Christopher A Petty
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Keertik Fulzele
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | | | - Werner Zwerschke
- Cell Metabolism and Differentiation Research Group, University of Innsbruck, Innsbruck, Austria
| | - Renata Pereira
- David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Kunzheng Wang
- Department of Orthopaedics, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China;
| | - Paola Divieti Pajevic
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA;
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14
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Inaba N, Kuroshima S, Uto Y, Sasaki M, Sawase T. Cyclic mechanical stretch contributes to network development of osteocyte-like cells with morphological change and autophagy promotion but without preferential cell alignment in rat. Biochem Biophys Rep 2017; 11:191-197. [PMID: 28955784 PMCID: PMC5614680 DOI: 10.1016/j.bbrep.2017.04.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 04/21/2017] [Accepted: 04/26/2017] [Indexed: 10/31/2022] Open
Abstract
Osteocytes play important roles in controlling bone quality as well as preferential alignment of biological apatite c-axis/collagen fibers. However, the relationship between osteocytes and mechanical stress remains unclear due to the difficulty of three-dimensional (3D) culture of osteocytes in vitro. The aim of this study was to investigate the effect of cyclic mechanical stretch on 3D-cultured osteocyte-like cells. Osteocyte-like cells were established using rat calvarial osteoblasts cultured in a 3D culture system. Cyclic mechanical stretch (8% amplitude at a rate of 2 cycles min-1) was applied for 24, 48 and 96 consecutive hours. Morphology, cell number and preferential cell alignment were evaluated. Apoptosis- and autophagy-related gene expression levels were measured using quantitative PCR. 3D-cultured osteoblasts became osteocyte-like cells that expressed osteocyte-specific genes such as Dmp1, Cx43, Sost, Fgf23 and RANKL, with morphological changes similar to osteocytes. Cell number was significantly decreased in a time-dependent manner under non-loaded conditions, whereas cyclic mechanical stretch significantly prevented decreased cell numbers with increased expression of anti-apoptosis-related genes. Moreover, cyclic mechanical stretch significantly decreased cell size and ellipticity with increased expression of autophagy-related genes, LC3b and atg7. Interestingly, preferential cell alignment did not occur, irrespective of mechanical stretch. These findings suggest that an anti-apoptotic effect contributes to network development of osteocyte-like cells under loaded condition. Spherical change of osteocyte-like cells induced by mechanical stretch may be associated with autophagy upregulation. Preferential alignment of osteocytes induced by mechanical load in vivo may be partially predetermined before osteoblasts differentiate into osteocytes and embed into bone matrix.
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Affiliation(s)
| | - Shinichiro Kuroshima
- Department of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1, Sakamoto, Nagasaki-city, Nagasaki 852-8588, Japan
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15
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Shah KM, Orton P, Mani N, Wilkinson JM, Gartland A. Osteocyte physiology and response to fluid shear stress are impaired following exposure to cobalt and chromium: Implications for bone health following joint replacement. J Orthop Res 2017; 35:1716-1723. [PMID: 27673573 PMCID: PMC5603770 DOI: 10.1002/jor.23449] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 09/23/2016] [Indexed: 02/04/2023]
Abstract
The effects of metal ion exposure on osteocytes, the most abundant cell type in bone and responsible for coordinating bone remodeling, remain unclear. However, several studies have previously shown that exposure to cobalt (Co2+ ) and chromium (Cr3+ ), at concentrations equivalent to those found clinically, affect osteoblast and osteoclast survival and function. In this study, we tested the hypothesis that metal ions would similarly impair the normal physiology of osteocytes. The survival, dendritic morphology, and response to fluid shear stress of the mature osteocyte-like cell-line MLO-Y4 following exposure to clinically relevant concentrations and combinations of Co and Cr ions were measured in 2D-culture. Exposure of MLO-Y4 cells to metal ions reduced cell number, increased dendrites per cell and increased dendrite length. We found that combinations of metal ions had a greater effect than the individual ions alone, and that Co2+ had a predominate effect on changes to cell numbers and dendrites. Combined metal ion exposure blunted the responses of the MLO-Y4 cells to fluid shear stress, including reducing the intracellular calcium responses and modulation of genes for the osteocyte markers Cx43 and Gp38, and the signaling molecules RANKL and Dkk-1. Finally, we demonstrated that in the late osteoblasts/early osteocytes cell line MLO-A5 that Co2+ exposure had no effect on mineralization, but Cr3+ treatment inhibited mineralization in a dose-dependent manner, without affecting cell viability. Taken together, these data indicate that metal exposure can directly affect osteocyte physiology, with potential implications for bone health including osseointegration of cementless components, and periprosthetic bone remodeling. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1716-1723, 2017.
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Affiliation(s)
- Karan M. Shah
- Department of Oncology and MetabolismThe University of SheffieldBeech Hill RdSheffield S10 2RXUnited Kingdom
| | - Peter Orton
- Department of Oncology and MetabolismThe University of SheffieldBeech Hill RdSheffield S10 2RXUnited Kingdom
| | - Nick Mani
- Department of Oncology and MetabolismThe University of SheffieldBeech Hill RdSheffield S10 2RXUnited Kingdom
| | - Jeremy Mark Wilkinson
- Department of Oncology and MetabolismThe University of SheffieldBeech Hill RdSheffield S10 2RXUnited Kingdom
| | - Alison Gartland
- Department of Oncology and MetabolismThe University of SheffieldBeech Hill RdSheffield S10 2RXUnited Kingdom
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16
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Kuroshima S, Kaku M, Ishimoto T, Sasaki M, Nakano T, Sawase T. A paradigm shift for bone quality in dentistry: A literature review. J Prosthodont Res 2017. [PMID: 28633987 DOI: 10.1016/j.jpor.2017.05.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
PURPOSE The aim of this study was to present the current concept of bone quality based on the proposal by the National Institutes of Health (NIH) and some of the cellular and molecular factors that affect bone quality. STUDY SELECTION This is a literature review which focuses on collagen, biological apatite (BAp), and bone cells such as osteoblasts and osteocytes. RESULTS In dentistry, the term "bone quality" has long been considered to be synonymous with bone mineral density (BMD) based on radiographic and sensible evaluations. In 2000, the NIH proposed the concept of bone quality as "the sum of all characteristics of bone that influence the bone's resistance to fracture," which is completely independent of BMD. The NIH defines bone quality as comprising bone architecture, bone turnover, bone mineralization, and micro-damage accumulation. Moreover, our investigations have demonstrated that BAp, collagen, and bone cells such as osteoblasts and osteocytes play essential roles in controlling the current concept of bone quality in bone around hip and dental implants. CONCLUSION The current concept of bone quality is crucial for understanding bone mechanical functions. BAp, collagen and osteocytes are the main factors affecting bone quality. Moreover, mechanical loading dynamically adapts bone quality. Understanding the current concept of bone quality is required in dentistry.
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Affiliation(s)
- Shinichiro Kuroshima
- Department of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1, Sakamoto, Nagasaki-city, Nagasaki 852-8588, Japan.
| | - Masaru Kaku
- Division of Bio-prosthodontics, Graduate School of Medical and Dental Science, Niigata University, 2-5274, Gakkocho-dori, Chuo-ku, Niigata-City, Niigata 951-8514, Japan
| | - Takuya Ishimoto
- Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita-city, Osaka 565-0871, Japan
| | - Muneteru Sasaki
- Department of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1, Sakamoto, Nagasaki-city, Nagasaki 852-8588, Japan
| | - Takayoshi Nakano
- Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita-city, Osaka 565-0871, Japan
| | - Takashi Sawase
- Department of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1, Sakamoto, Nagasaki-city, Nagasaki 852-8588, Japan
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17
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Cavani F, Ferretti M, Smargiassi A, Palumbo C. PTH(1-34) effects on repairing experimentally drilled holes in rat femur: novel aspects - qualitative vs. quantitative improvement of osteogenesis. J Anat 2016; 230:75-84. [PMID: 27523886 DOI: 10.1111/joa.12533] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2016] [Indexed: 12/26/2022] Open
Abstract
The timetable of effects on bone repair of the active fraction-parathyroid hormone, PTH(1-34), was analytically investigated from the morphometric viewpoint in 3-month-old male Sprague-Dawley rats, whose femurs were drilled at mid-diaphyseal level (transcortical holes). The animals were divided into groups with/without PTH(1-34) administration, and sacrificed at different times (10, 28, 45 days after surgery). The observations reported here need to be framed in the context of our previous investigations regarding bone histogenesis (Ferretti et al. Anat Embryol. 2002; 206: 21-29) in which we demonstrated the occurrence of two successive bone-forming processes during both skeletal organogenesis and bone repair, i.e. static and dynamic osteogenesis: the former (due to stationary osteoblasts, haphazardly grouped in cords) producing preliminary bad quality trabecular bone, the latter (due to typical polarized osteoblasts organized in ordered movable laminae) producing mechanically valid bone tissue. The primary function of static osteogenesis is to provide a rigid scaffold containing osteocytes (i.e. mechano-sensors) for osteoblast laminae acting in dynamic osteogenesis. In the present work, histomorphometric analysis revealed that, already 10 days after drilling, despite the holes being temporarily filled by the same amount of newly formed trabecular bone by static osteogenesis independently of the treatment, the extent of the surface of movable osteoblast-laminae (covering the trabecular surface) was statistically higher in animals submitted to PTH(1-34) administration than in control ones; this datum strongly suggests the effect of PTH(1-34) alone in anticipating the occurrence of dynamic osteogenesis involved in the production of good quality bone (with more ordered collagen texture) more suitable for loading. This study could be crucial in further translational clinical research in humans for defining the best therapeutic strategies to be applied in recovering severe skeletal lesions, particularly as regards the time of PTH(1-34) administration.
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Affiliation(s)
- Francesco Cavani
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze - Sez. Morfologia umana, Università di Modena e Reggio Emilia, Modena, Italy
| | - Marzia Ferretti
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze - Sez. Morfologia umana, Università di Modena e Reggio Emilia, Modena, Italy
| | - Alberto Smargiassi
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze - Sez. Morfologia umana, Università di Modena e Reggio Emilia, Modena, Italy
| | - Carla Palumbo
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze - Sez. Morfologia umana, Università di Modena e Reggio Emilia, Modena, Italy
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18
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Toscani D, Palumbo C, Dalla Palma B, Ferretti M, Bolzoni M, Marchica V, Sena P, Martella E, Mancini C, Ferri V, Costa F, Accardi F, Craviotto L, Aversa F, Giuliani N. The Proteasome Inhibitor Bortezomib Maintains Osteocyte Viability in Multiple Myeloma Patients by Reducing Both Apoptosis and Autophagy: A New Function for Proteasome Inhibitors. J Bone Miner Res 2016; 31:815-27. [PMID: 26551485 DOI: 10.1002/jbmr.2741] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 11/06/2015] [Accepted: 11/08/2015] [Indexed: 11/11/2022]
Abstract
Multiple myeloma (MM) is characterized by severely imbalanced bone remodeling. In this study, we investigated the potential effect of proteasome inhibitors (PIs), a class of drugs known to stimulate bone formation, on the mechanisms involved in osteocyte death induced by MM cells. First, we performed a histological analysis of osteocyte viability on bone biopsies on a cohort of 37 MM patients with symptomatic disease. A significantly higher number of viable osteocytes was detected in patients treated with a bortezomib (BOR)-based regimen compared with those treated without BOR. Interestingly, both osteocyte autophagy and apoptosis were affected in vivo by BOR treatment. Thereafter, we checked the in vitro effect of BOR to understand the mechanisms whereby BOR maintains osteocyte viability in bone from MM patients. We found that osteocyte and preosteocyte autophagic death was triggered during coculturing with MM cells. Our evaluation was conducted by analyzing either autophagy markers microtubule-associated protein light chain 3 beta (LC3B) and SQSTM1/sequestome 1 (p62) levels, or the cell ultrastructure by transmission electron microscopy. PIs were found to increase the basal levels of LC3 expression in the osteocytes while blunting the myeloma-induced osteocyte death. PIs also reduced the autophagic death of osteocytes induced by high-dose dexamethasone (DEX) and potentiated the anabolic effect of PTH(1-34). Our data identify osteocyte autophagy as a new potential target in MM bone disease and support the use of PIs to maintain osteocyte viability and improve bone integrity in MM patients.
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Affiliation(s)
- Denise Toscani
- Myeloma Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy
| | - Carla Palumbo
- Department of Biomedical, Metabolic, and Neural Sciences, Section of Human Morphology, University of Modena and Reggio Emilia, Modena, Italy
| | - Benedetta Dalla Palma
- Myeloma Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.,Hematology Unit, "Azienda Ospedaliero-Universitaria di Parma", Parma, Italy
| | - Marzia Ferretti
- Department of Biomedical, Metabolic, and Neural Sciences, Section of Human Morphology, University of Modena and Reggio Emilia, Modena, Italy
| | - Marina Bolzoni
- Myeloma Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy
| | - Valentina Marchica
- Myeloma Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy
| | - Paola Sena
- Department of Biomedical, Metabolic, and Neural Sciences, Section of Human Morphology, University of Modena and Reggio Emilia, Modena, Italy
| | - Eugenia Martella
- Pathology, "Azienda Ospedaliero-Universitaria di Parma", Parma, Italy
| | - Cristina Mancini
- Pathology, "Azienda Ospedaliero-Universitaria di Parma", Parma, Italy
| | - Valentina Ferri
- Myeloma Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.,Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | - Federica Costa
- Myeloma Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy
| | - Fabrizio Accardi
- Myeloma Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.,Hematology Unit, "Azienda Ospedaliero-Universitaria di Parma", Parma, Italy
| | - Luisa Craviotto
- Myeloma Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy
| | - Franco Aversa
- Myeloma Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.,Hematology Unit, "Azienda Ospedaliero-Universitaria di Parma", Parma, Italy
| | - Nicola Giuliani
- Myeloma Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.,Hematology Unit, "Azienda Ospedaliero-Universitaria di Parma", Parma, Italy
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19
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Liu C, Zhang X, Wu M, You L. Mechanical loading up-regulates early remodeling signals from osteocytes subjected to physical damage. J Biomech 2015; 48:4221-8. [DOI: 10.1016/j.jbiomech.2015.10.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 09/15/2015] [Accepted: 10/18/2015] [Indexed: 11/17/2022]
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20
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Sun Q, Gu Y, Zhang W, Dziopa L, Zilberberg J, Lee W. Ex vivo 3D osteocyte network construction with primary murine bone cells. Bone Res 2015; 3:15026. [PMID: 26421212 PMCID: PMC4576492 DOI: 10.1038/boneres.2015.26] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 07/14/2015] [Accepted: 08/11/2015] [Indexed: 01/23/2023] Open
Abstract
Osteocytes reside as three-dimensionally (3D) networked cells in the lacunocanalicular structure of bones and regulate bone and mineral homeostasis. Despite of their important regulatory roles, in vitro studies of osteocytes have been challenging because: (1) current cell lines do not sufficiently represent the phenotypic features of mature osteocytes and (2) primary cells rapidly differentiate to osteoblasts upon isolation. In this study, we used a 3D perfusion culture approach to: (1) construct the 3D cellular network of primary murine osteocytes by biomimetic assembly with microbeads and (2) reproduce ex vivo the phenotype of primary murine osteocytes, for the first time to our best knowledge. In order to enable 3D construction with a sufficient number of viable cells, we used a proliferated osteoblastic population of healthy cells outgrown from digested bone chips. The diameter of microbeads was controlled to: (1) distribute and entrap cells within the interstitial spaces between the microbeads and (2) maintain average cell-to-cell distance to be about 19 µm. The entrapped cells formed a 3D cellular network by extending and connecting their processes through openings between the microbeads. Also, with increasing culture time, the entrapped cells exhibited the characteristic gene expressions (SOST and FGF23) and nonproliferative behavior of mature osteocytes. In contrast, 2D-cultured cells continued their osteoblastic differentiation and proliferation. This 3D biomimetic approach is expected to provide a new means of: (1) studying flow-induced shear stress on the mechanotransduction function of primary osteocytes, (2) studying physiological functions of 3D-networked osteocytes with in vitro convenience, and (3) developing clinically relevant human bone disease models.
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Affiliation(s)
- Qiaoling Sun
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology , Hoboken, NJ, USA
| | - Yexin Gu
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology , Hoboken, NJ, USA
| | - Wenting Zhang
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology , Hoboken, NJ, USA
| | - Leah Dziopa
- John Theurer Cancer Center, Hackensack University Medical Center , Hackensack, NJ, USA
| | - Jenny Zilberberg
- John Theurer Cancer Center, Hackensack University Medical Center , Hackensack, NJ, USA
| | - Woo Lee
- Department of Materials Science and Chemical Engineering, Stevens Institute of Technology , Hoboken, NJ, USA
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21
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Kringelbach TM, Aslan D, Novak I, Ellegaard M, Syberg S, Andersen CKB, Kristiansen KA, Vang O, Schwarz P, Jørgensen NR. Fine-tuned ATP signals are acute mediators in osteocyte mechanotransduction. Cell Signal 2015; 27:2401-9. [PMID: 26327582 DOI: 10.1016/j.cellsig.2015.08.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 08/24/2015] [Accepted: 08/26/2015] [Indexed: 12/12/2022]
Abstract
Osteocytes are considered the primary mechanosensors of bone, but the signaling pathways they apply in mechanotransduction are still incompletely investigated and characterized. A growing body of data strongly indicates that P2 receptor signaling among osteoblasts and osteoclasts has regulatory effects on bone remodeling. Therefore, we hypothesized that ATP signaling is also applied by osteocytes in mechanotransduction. We applied a short fluid pulse on MLO-Y4 osteocyte-like cells during real-time detection of ATP and demonstrated that mechanical stimulation activates the acute release of ATP and that these acute ATP signals are fine-tuned according to the magnitude of loading. ATP release was then challenged by pharmacological inhibitors, which indicated a vesicular release pathway for acute ATP signals. Finally, we showed that osteocytes express functional P2X2 and P2X7 receptors and respond to even low concentrations of nucleotides by increasing intracellular calcium concentration. These results indicate that in osteocytes, vesicular ATP release is an acute mediator of mechanical signals and the magnitude of loading. These and previous results, therefore, implicate purinergic signaling as an early signaling pathway in osteocyte mechanotransduction.
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Affiliation(s)
- Tina M Kringelbach
- Research Center for Ageing and Osteoporosis, Department of Diagnostics, Copenhagen University Hospital Glostrup, Glostrup, Denmark; Research Center for Ageing and Osteoporosis, Department of Medicine, Copenhagen University Hospital Glostrup, Glostrup, Denmark; The Osteoporosis and Bone Metabolic Unit, Dept. of Endocrinology, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; The Osteoporosis and Bone Metabolic Unit, Dept. of Clinical Biochemistry, Copenhagen, University Hospital Hvidovre, Hvidovre, Denmark
| | - Derya Aslan
- Research Center for Ageing and Osteoporosis, Department of Diagnostics, Copenhagen University Hospital Glostrup, Glostrup, Denmark; Research Center for Ageing and Osteoporosis, Department of Medicine, Copenhagen University Hospital Glostrup, Glostrup, Denmark
| | - Ivana Novak
- Department of Biology, University of Copenhagen, Copenhagen Ø, Denmark
| | - Maria Ellegaard
- Research Center for Ageing and Osteoporosis, Department of Diagnostics, Copenhagen University Hospital Glostrup, Glostrup, Denmark; Research Center for Ageing and Osteoporosis, Department of Medicine, Copenhagen University Hospital Glostrup, Glostrup, Denmark
| | - Susanne Syberg
- Research Center for Ageing and Osteoporosis, Department of Diagnostics, Copenhagen University Hospital Glostrup, Glostrup, Denmark; Research Center for Ageing and Osteoporosis, Department of Medicine, Copenhagen University Hospital Glostrup, Glostrup, Denmark
| | - Christina K B Andersen
- Research Center for Ageing and Osteoporosis, Department of Diagnostics, Copenhagen University Hospital Glostrup, Glostrup, Denmark; Research Center for Ageing and Osteoporosis, Department of Medicine, Copenhagen University Hospital Glostrup, Glostrup, Denmark
| | - Kim A Kristiansen
- Department of Clinical Research, Copenhagen University Hospital Glostrup, Glostrup, Denmark
| | - Ole Vang
- Department of Science, Systems and Models, Roskilde University, Roskilde, Denmark
| | - Peter Schwarz
- Research Center for Ageing and Osteoporosis, Department of Diagnostics, Copenhagen University Hospital Glostrup, Glostrup, Denmark; Research Center for Ageing and Osteoporosis, Department of Medicine, Copenhagen University Hospital Glostrup, Glostrup, Denmark; Faculty of Health Science, University of Copenhagen, Copenhagen, Denmark
| | - Niklas R Jørgensen
- Research Center for Ageing and Osteoporosis, Department of Diagnostics, Copenhagen University Hospital Glostrup, Glostrup, Denmark; Research Center for Ageing and Osteoporosis, Department of Medicine, Copenhagen University Hospital Glostrup, Glostrup, Denmark; The Osteoporosis and Bone Metabolic Unit, Dept. of Endocrinology, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; The Osteoporosis and Bone Metabolic Unit, Dept. of Clinical Biochemistry, Copenhagen, University Hospital Hvidovre, Hvidovre, Denmark.
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22
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Maycas M, Ardura JA, de Castro LF, Bravo B, Gortázar AR, Esbrit P. Role of the Parathyroid Hormone Type 1 Receptor (PTH1R) as a Mechanosensor in Osteocyte Survival. J Bone Miner Res 2015; 30:1231-44. [PMID: 25529820 DOI: 10.1002/jbmr.2439] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 11/22/2014] [Accepted: 12/22/2014] [Indexed: 12/13/2022]
Abstract
Osteocytes have a major role in the control of bone remodeling. Mechanical stimulation decreases osteocyte apoptosis and promotes bone accrual, whereas skeletal unloading is deleterious in both respects. PTH1R ablation or overexpression in osteocytes in mice produces trabecular bone loss or increases bone mass, respectively. The latter effect was related to a decreased osteocyte apoptosis. Here, the putative role of PTH1R activation in osteocyte protection conferred by mechanical stimulation was assessed. Osteocytic MLO-Y4 cells were subjected to mechanical stimuli represented by hypotonic shock (216 mOsm/kg) or pulsatile fluid flow (8 Hz, 10 dynes/cm(2)) for a short pulse (10 min), with or without PTH1R antagonists or after transfection with specific PTHrP or PTH1R siRNA. These mechanical stimuli prevented cell death induced within 6 hours by etoposide (50 μM), related to PTHrP overexpression; and this effect was abolished by the calcium antagonist verapamil (1 μM), a phospholipase C (PLC) inhibitor (U73122; 10 μM), and a PKA activation inhibitor, Rp-cAMPS (25 μM), in these cells. Each mechanical stimulus also rapidly induced β-catenin stabilization and nuclear ERK translocation, which were inhibited by the PTH1R antagonist PTHrP(7-34) (1 μM), or PTH1R siRNA, and mimicked by PTHrP(1-36) (100 nM). Mechanical stretching by hypotonic shock did not affect cAMP production but rapidly (<1 min) stimulated Ca(i)(2+) transients in PTH1R-overexpressing HEK-293 cells and in MLO-Y4 cells, in which calcium signaling was unaffected by the presence of a PTHrP antiserum or PTHrP siRNA but inhibited by knocking down PTH1R. These novel findings indicate that PTH1R is an important component of mechanical signal transduction in osteocytic MLO-Y4 cells, and that PTH1R activation by PTHrP-independent and dependent mechanisms has a relevant role in the prosurvival action of mechanical stimulus in these cells.
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Affiliation(s)
- Marta Maycas
- Instituto de, Investigación Sanitaria (IIS)-, Fundación Jiménez Díaz, Universidad Autónoma de Madrid (UAM) and Red Temática de Investigación Cooperativa en Envejecimiento y Fragilidad (RETICEF), Madrid, Spain
| | - Juan A Ardura
- Instituto de, Investigación Sanitaria (IIS)-, Fundación Jiménez Díaz, Universidad Autónoma de Madrid (UAM) and Red Temática de Investigación Cooperativa en Envejecimiento y Fragilidad (RETICEF), Madrid, Spain
| | - Luis F de Castro
- Instituto de Medicina Molecular Aplicada (IMMA), Facultad de Medicina, Universidad San Pablo-CEU, Madrid, Spain
| | - Beatriz Bravo
- Instituto de Medicina Molecular Aplicada (IMMA), Facultad de Medicina, Universidad San Pablo-CEU, Madrid, Spain
| | - Arancha R Gortázar
- Instituto de Medicina Molecular Aplicada (IMMA), Facultad de Medicina, Universidad San Pablo-CEU, Madrid, Spain
| | - Pedro Esbrit
- Instituto de, Investigación Sanitaria (IIS)-, Fundación Jiménez Díaz, Universidad Autónoma de Madrid (UAM) and Red Temática de Investigación Cooperativa en Envejecimiento y Fragilidad (RETICEF), Madrid, Spain
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23
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Fontani F, Marcucci G, Iantomasi T, Brandi ML, Vincenzini MT. Glutathione, N-acetylcysteine and lipoic acid down-regulate starvation-induced apoptosis, RANKL/OPG ratio and sclerostin in osteocytes: involvement of JNK and ERK1/2 signalling. Calcif Tissue Int 2015; 96:335-46. [PMID: 25660312 DOI: 10.1007/s00223-015-9961-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 02/02/2015] [Indexed: 12/22/2022]
Abstract
Osteocyte apoptosis due to microdamage and/or oxidative stress is related to increased local bone turnover and resorption observed in various bone diseases. Previous data on osteoblasts and osteoclasts have linked reactive oxygen species and antioxidants to bone remodelling. This study performs a comprehensive analysis on the effect of antioxidants such as glutathione (GSH), N-acetylcysteine and lipoic acid (LA) on starvation-induced osteocyte apoptosis and on cytokines involved in bone remodelling such as the receptor activator kB ligand (RANKL), osteoprotegerin (OPG) and sclerostin. For this study, apoptosis was induced by serum starvation in a murine osteocyte-like cell line MLO-Y4; this condition mimics in part osteocyte apoptosis due to microdamage. The results show that starvation-induced apoptosis and expression of RANKL, OPG and sclerostin are redox regulated processes. All antioxidants are able to inhibit the apoptosis due to starvation. They down-regulate the expression and the release of RANKL, the expression of sclerostin and RANKL/OPG ratio, whereas they only in part up-regulate OPG expression. Antioxidants mediate their effect on starvation-induced apoptosis by JNK signalling and on cytokine expression by both JNK and ERK1/2 activities. This study shows the possible involvement of biological antioxidants such as GSH and LA on redox regulated mechanisms related to apoptosis and expression of cytokines involved in bone remodelling. Moreover, it suggests that both JNK and ERK1/2 may be useful biological targets for drugs affecting bone diseases associated with increased oxidative stress.
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Affiliation(s)
- Filippo Fontani
- Department of Biomedical, Experimental and Clinical Sciences, University of Florence, Viale Morgagni 50, 50134, Florence, Italy
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24
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Honma M, Ikebuchi Y, Kariya Y, Suzuki H. Establishment of optimized in vitro assay methods for evaluating osteocyte functions. J Bone Miner Metab 2015; 33:73-84. [PMID: 24381056 DOI: 10.1007/s00774-013-0555-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 11/25/2013] [Indexed: 01/22/2023]
Abstract
Recent studies have revealed that osteocytes play multiple important physiological roles. To analyze osteocyte functions in detail, an in vitro experimental system for primary osteocytes would be useful. Unfortunately, osteocytes tend to dedifferentiate and acquire osteoblast-like features even when the cells are cultured in three-dimensional (3D) collagen gel. Therefore, it is desirable to establish osteocyte culture conditions that prevent dedifferentiation over longer periods. In this study, we obtained systematic information about the influence of culture conditions on osteocyte differentiation states. Fetal bovine serum (FBS) concentrations from 0.1 to 0.5 % in 3D culture matrix did not significantly influence the expression of osteocyte markers. On the other hand, addition of Matrigel to the culture matrix significantly enhanced the expression of Rankl and late osteocyte markers such as Sost and Fgf23. Matrigel addition also inhibited upregulation of Opg and early osteocyte markers such as Dmp1 and Gp38. These effects on osteocyte properties were maximal at a Matrigel culture matrix content of 50 %. Matrigel addition to the matrix also increased dendritic process extension by osteocytes. In addition, Matrigel addition significantly stimulated tartrate-resistant acid phosphatase activity in co-culture with bone marrow macrophages. Among the conditions tested, 50 % Matrigel and 0.2 % FBS in type I collagen matrix were optimal for culture of primary osteocytes.
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Affiliation(s)
- Masashi Honma
- Department of Pharmacy, The University of Tokyo Hospital, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan,
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25
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Turner AG, Hanrath MA, Morris HA, Atkins GJ, Anderson PH. The local production of 1,25(OH)2D3 promotes osteoblast and osteocyte maturation. J Steroid Biochem Mol Biol 2014; 144 Pt A:114-8. [PMID: 24125735 DOI: 10.1016/j.jsbmb.2013.10.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 09/27/2013] [Accepted: 10/01/2013] [Indexed: 10/26/2022]
Abstract
Maintenance of an adequate vitamin D status, as indicated by the level of circulating 25-hydroxyvitamin D (25(OH)D), is associated with higher bone mass and decreased risk of fracture. However, the molecular actions of vitamin D hormone (1,25(OH)2D3) in bone are complex, and include stimulation of osteoclastogenesis via RANK-ligand up-regulation, as well as the inhibition of mineralisation. We hypothesise that these divergent data may be reconciled by autocrine actions of 1,25(OH)2D3 which effect skeletal maintenance, as opposed to endocrine 1,25(OH)2D3 which acts to maintain serum calcium homeostasis. We have previously described local metabolism of 1,25(OH)2D3 within osteoblasts, with effects on gene expression and cell function. The aim of the current study was to investigate potential autocrine actions of 1,25(OH)2D3 within cells that exhibit osteocyte-like properties. Late osteoblastic MLO-A5 cells were cultured in the presence of 25(OH)D for 9 days with gene expression analysed pre- and post-mineralisation. Gene expression analysis revealed maturation within this time frame to an osteocyte-like stage, evidenced by increased Dmp1 and Phex mRNA expression. Expression of Cyp27b1 in 25(OH)D treated MLO-A5 cells was associated with elevated media levels of 1,25(OH)2D3 (p<0.05), induction of Cyp24a1 (p<0.001) and elevated ratios of Opg:Rankl mRNA (p<0.01). Chronic 25(OH)D exposure also increased osteocalcin mRNA in MLO-A5 cells, which contrasted with the dose-dependent inhibition of osteocalcin mRNA observed with acute treatment in MLO-Y4 cells (p<0.01). Treatment of MLO-Y4 cells with 25(OH)D also inhibited Phex mRNA expression (p<0.05), whilst Enpp1 gene expression was induced (p<0.01). Overall, the current study demonstrates that osteocyte-like cells convert physiological levels of 25(OH)D to 1,25(OH)2D3, with changes in gene expression that are consistent with increased osteocyte maturation. Although the physiological role of local metabolism of 1,25(OH)2D3 within osteocytes requires further investigation, the abundance and diverse functions of this cell type within bone underscore its potential importance. This article is part of a Special Issue entitled '16th Vitamin D Workshop'.
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Affiliation(s)
- Andrew G Turner
- Centre for Musculoskeletal Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia.
| | | | - Howard A Morris
- Centre for Musculoskeletal Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Gerald J Atkins
- Centre for Orthopaedic and Trauma Research, University of Adelaide, SA 5005, Australia
| | - Paul H Anderson
- Centre for Musculoskeletal Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia
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26
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St John HC, Bishop KA, Meyer MB, Benkusky NA, Leng N, Kendziorski C, Bonewald LF, Pike JW. The osteoblast to osteocyte transition: epigenetic changes and response to the vitamin D3 hormone. Mol Endocrinol 2014; 28:1150-65. [PMID: 24877565 DOI: 10.1210/me.2014-1091] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Osteocytes are derived from osteoblast lineage cells that become progressively embedded in mineralized bone. Development of the osteocytogenic cell line IDG-SW3 has enabled a temporal and mechanistic investigation of this process. Through RNA-sequencing analyses, we show that although substantial changes in gene expression occur during the osteoblast to osteocyte transition, the majority of the transcriptome remains qualitatively osteoblast like. Genes either up-regulated or expressed uniquely in the osteocyte include local and systemic factors such as Sost and Fgf23 as well as genes implicated in neuronal, muscle, vascular, or regulatory function. As assessed by chromatin immunoprecipitation coupled to high-throughput sequencing, numerous changes in epigenetic histone modifications also occur during osteocytogenesis; these are largely qualitative rather than quantitative. Specific epigenetic changes correlate with altered gene expression patterns that are observed during the transition. These genomic changes likely influence the highly restricted transcriptomic response to 1,25(OH)(2)D(3) that occurs during differentiation. VDR binding in osteocytes revealed an extensive cistrome co-occupied by retinoid X receptor and located predominantly at sites distal to regulated genes. Although sites of VDR binding were apparent near many 1,25(OH)(2)D(3)-regulated genes, the expression of others adjacent to VDR-binding sites were unaffected; lack of VDR binding was particularly prevalent at down-regulated genes. Interestingly, 1,25(OH)(2)D(3) was found to induce the Boc and Cdon coreceptors that are active in hedgehog signaling in osteocytes. We conclude that osteocytogenesis is accompanied by changes in gene expression that may be driven by both genetic and epigenetic components. These changes are likely responsible for the osteocyte phenotype and may contribute to reduced sensitivity to 1,25(OH)(2)D(3).
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Affiliation(s)
- Hillary C St John
- Department of Biochemistry (H.C.S., K.A.B., M.B.M., N.A.B., J.W.P.) and Department of Biostatistics (N.L., C.K.), University of Wisconsin-Madison, Madison, Wisconsin 53706; and Department of Oral Biology (L.F.B.), School of Dentistry, University of Missouri, Kansas City, Missouri 6410
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27
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Abstract
Few investigators think of bone as an endocrine gland, even after the discovery that osteocytes produce circulating fibroblast growth factor 23 that targets the kidney and potentially other organs. In fact, until the last few years, osteocytes were perceived by many as passive, metabolically inactive cells. However, exciting recent discoveries have shown that osteocytes encased within mineralized bone matrix are actually multifunctional cells with many key regulatory roles in bone and mineral homeostasis. In addition to serving as endocrine cells and regulators of phosphate homeostasis, these cells control bone remodeling through regulation of both osteoclasts and osteoblasts, are mechanosensory cells that coordinate adaptive responses of the skeleton to mechanical loading, and also serve as a manager of the bone's reservoir of calcium. Osteocytes must survive for decades within the bone matrix, making them one of the longest lived cells in the body. Viability and survival are therefore extremely important to ensure optimal function of the osteocyte network. As we continue to search for new therapeutics, in addition to the osteoclast and the osteoblast, the osteocyte should be considered in new strategies to prevent and treat bone disease.
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Affiliation(s)
- Sarah L Dallas
- PhD, Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, 650 East 25th Street, Kansas City, Missouri 64108.
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28
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Mullen CA, Haugh MG, Schaffler MB, Majeska RJ, McNamara LM. Osteocyte differentiation is regulated by extracellular matrix stiffness and intercellular separation. J Mech Behav Biomed Mater 2013; 28:183-94. [PMID: 23994943 DOI: 10.1016/j.jmbbm.2013.06.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 06/14/2013] [Accepted: 06/28/2013] [Indexed: 01/04/2023]
Abstract
Osteocytes are terminally differentiated bone cells, derived from osteoblasts, which are vital for the regulation of bone formation and resorption. ECM stiffness and cell seeding density have been shown to regulate osteoblast differentiation, but the precise cues that initiate osteoblast-osteocyte differentiation are not yet understood. In this study, we cultured MC3T3-E1 cells on (A) substrates of different chemical compositions and stiffnesses, as well as, (B) substrates of identical chemical composition but different stiffnesses. The effect of cell separation was investigated by seeding cells at different densities on each substrate. Cells were evaluated for morphology, alkaline phosphatase (ALP), matrix mineralisation, osteoblast specific genes (Type 1 collagen, Osteoblast specific factor (OSF-2)), and osteocyte specific proteins (dentin matrix protein 1 (DMP-1), sclerostin (Sost)). We found that osteocyte differentiation (confirmed by dendritic morphology, mineralisation, reduced ALP, Col type 1 and OSF-2 and increased DMP-1 and Sost expression) was significantly increased on soft collagen based substrates, at low seeding densities compared to cells on stiffer substrates or those plated at high seeding density. We propose that the physical nature of the ECM and the necessity for cells to establish a communication network contribute substantially to a concerted shift toward an osteocyte-like phenotype by osteoblasts in vitro.
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Affiliation(s)
- C A Mullen
- Centre for Biomechanics Research (BMEC), Mechanical and Biomedical Engineering, NUI Galway, Ireland; National Centre for Biomedical Engineering Science (NCBES), NUI Galway, Ireland
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29
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Nguyen AM, Jacobs CR. Emerging role of primary cilia as mechanosensors in osteocytes. Bone 2013; 54:196-204. [PMID: 23201223 PMCID: PMC3624072 DOI: 10.1016/j.bone.2012.11.016] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 10/06/2012] [Accepted: 11/19/2012] [Indexed: 01/08/2023]
Abstract
The primary cilium is a solitary, immotile microtubule-based extension present on nearly every mammalian cell. This organelle has established mechanosensory roles in several contexts including kidney, liver, and the embryonic node. Mechanical load deflects the cilium, triggering biochemical responses. Defects in cilium function have been associated with numerous human diseases. Recent research has implicated the primary cilium as a mechanosensor in bone. In this review, we discuss the cilium, the growing evidence for its mechanosensory role in bone, and areas of future study.
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Affiliation(s)
- An M Nguyen
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA
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30
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Stern AR, Stern MM, Van Dyke ME, Jähn K, Prideaux M, Bonewald LF. Isolation and culture of primary osteocytes from the long bones of skeletally mature and aged mice. Biotechniques 2012; 52:361-73. [PMID: 22668415 PMCID: PMC3612989 DOI: 10.2144/0000113876] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 05/18/2012] [Indexed: 12/20/2022] Open
Abstract
The purpose of this work was to establish a methodology to enable the isolation and study of osteocytes from skeletally mature young (4-month-old) and old (22-month-old) mice. The location of osteocytes deep within bone is ideal for their function as mechanosensors. However, this location makes the observation and study of osteocytes in vivo technically difficult. Osteocytes were isolated from murine long bones through a process of extended collagenase digestions combined with EDTA-based decalcification. A tissue homogenizer was used to reduce the remaining bone fragments to a suspension of bone particles, which were placed in culture to yield an outgrowth of osteocyte-like cells. All of the cells obtained from this outgrowth that displayed an osteocyte-like morphology stained positive for the osteocyte marker E11/GP38. The osteocyte phenotype was further confirmed by a lack of staining for alkaline phosphatase and the absence of collagen1a1 expression. The outgrowth of osteocytes also expressed additional osteocyte-specific genes such as Sost and Mepe. This technique facilitates the isolation of osteocytes from skeletally mature bone. This novel enabling methodology should prove useful in advancing our understanding of the roles mature osteocytes play in bone health and disease.
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Affiliation(s)
- Amber Rath Stern
- Mechanical Engineering and Oral Biology, University of Missouri Kansas City, Kansas City, MO, USA.
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31
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Guntur AR, Rosen CJ, Naski MC. N-cadherin adherens junctions mediate osteogenesis through PI3K signaling. Bone 2012; 50:54-62. [PMID: 21964322 PMCID: PMC3251172 DOI: 10.1016/j.bone.2011.09.036] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Revised: 08/22/2011] [Accepted: 09/07/2011] [Indexed: 01/18/2023]
Abstract
During endochondral ossification, the cartilage is surrounded by a layer of cells that constitute the perichondrium. Communication between osteoblasts in the perichondrium via N-cadherin adherens junctions is essential for endochondral bone growth. We observed that adherens junction molecule N-cadherin and its interacting partners p120, β-catenin and PTEN are expressed by cells present in the perichondrium. To study if N-cadherin mediated adherens junctions play a role in mediating signal transduction events during bone development, we utilized MC3T3E1 preosteoblasts plated at sub confluent (low) and confluent (high) densities to mimic adherens junction formation. When MC3T3E1 cells were plated at high density we observed an increase in phosphorylation of AKTSer473 and its downstream target GSK3Ser9, which coincided with an increase in Osterix, Osteomodulin and Osteoglycin gene expression. Using immunofluorescence, we identified N-cadherin, p120 and β-catenin localized at the membrane of MC3T3E1 cells. Treatment of confluent MC3T3E1 cells with an N-cadherin junction inhibitor-EGTA and a PI3K inhibitor LY294002 resulted in reduction of phosphorylation levels of AKT and GSK3 and expression of Osterix, Osteomodulin and Osteoglycin. Furthermore, utilizing an N-cadherin blocking antibody resulted in reduced AKT signaling and Osterix gene expression, suggesting that osteoblast junction formation is linked to activation of PI3K signaling, which leads to osteoblast differentiation. To further explore the strength of this linkage, we utilized a conditional knockout approach using Dermo1cre to delete β-catenin and PTEN, two important proteins known to be essential for adherens junctions and PI3K signaling, respectively. In the absence of β-catenin, we observed a decrease in adherens junctions and AKT signaling in the perichondrium. PTEN deletion, on the other hand, increased the number of cells expressing N-cadherin in the perichondrium. These observations show that N-cadherin mediated junctions between osteoblasts are needed for osteoblast gene transcription.
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Affiliation(s)
- Anyonya R Guntur
- Department of Biochemistry University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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32
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Kamel MA, Picconi JL, Lara-Castillo N, Johnson ML. Activation of β-catenin signaling in MLO-Y4 osteocytic cells versus 2T3 osteoblastic cells by fluid flow shear stress and PGE2: Implications for the study of mechanosensation in bone. Bone 2010; 47:872-81. [PMID: 20713195 PMCID: PMC2952691 DOI: 10.1016/j.bone.2010.08.007] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 07/19/2010] [Accepted: 08/10/2010] [Indexed: 12/20/2022]
Abstract
The osteocyte is hypothesized to be the mechanosensory cell in bone. However, osteoblastic cell models have been most commonly used to investigate mechanisms of mechanosensation in bone. Therefore, we sought to determine if differences might exist between osteocytic and osteoblastic cell models relative to the activation of β-catenin signaling in MLO-Y4 osteocytic, 2T3 osteoblastic and primary neonatal calvarial cells (NCCs) in response to pulsatile fluid flow shear stress (PFFSS). β-catenin nuclear translocation was observed in the MLO-Y4 cells at 2 and 16 dynes/cm(2) PFFSS, but only at 16 dynes/cm(2) in the 2T3 or NCC cultures. The MLO-Y4 cells released high amounts of PGE(2) into the media at all levels of PFFSS (2-24 dynes/cm(2)) and we observed a biphasic pattern relative to the level of PFFSS. In contrast PGE(2) release by 2T3 cells was only detected during 16 and 24 dynes/cm(2) PFFSS starting at >1h and never reached the levels produced by the MLO-Y4 cells. Exogenously added PGE(2) was able to induce β-catenin nuclear translocation in all cells suggesting that the differences between the cell lines observed for β-catenin nuclear translocation were associated with the differences in PGE(2) production. To investigate a possible mechanism for the differences in PGE(2) release by the MLO-Y4 and 2T3 cells we examined the regulation of Ptgs2 (Cox-2) gene expression by PFFSS. 2T3 cell Ptgs2 mRNA levels at both 0 and 24h after 2h of PFFSS showed biphasic increases with peaks at 4 and 24 dynes/cm(2) and 24-hour levels were higher than zero-hour levels. MLO-Y4 cell Ptgs2 expression was similarly biphasic; however at 24-hour post-flow Ptgs2 mRNA levels were lower. Our data suggest significant differences in the sensitivity and kinetics of the response mechanisms of the 2T3 and neonatal calvarial osteoblastic versus MLO-Y4 osteocytic cells to PFFSS. Furthermore our data support a role for PGE(2) in mediating the activation of β-catenin signaling in response to the fluid flow shear stress.
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Affiliation(s)
- Mohamed A. Kamel
- Department of Oral Biology, UMKC School of Dentistry, 650 East 25 Street, Kansas City, MO 64108
| | - Jason L. Picconi
- Department of Department of Obstetrics and Gynecology, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242
| | - Nuria Lara-Castillo
- Department of Oral Biology, UMKC School of Dentistry, 650 East 25 Street, Kansas City, MO 64108
| | - Mark L. Johnson
- Department of Oral Biology, UMKC School of Dentistry, 650 East 25 Street, Kansas City, MO 64108
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Lai Y, Sun Y, Skinner CM, Son EL, Lu Z, Tuan RS, Jilka RL, Ling J, Chen XD. Reconstitution of marrow-derived extracellular matrix ex vivo: a robust culture system for expanding large-scale highly functional human mesenchymal stem cells. Stem Cells Dev 2010; 19:1095-107. [PMID: 19737070 DOI: 10.1089/scd.2009.0217] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The difficulty in long-term expansion of mesenchymal stem cells (MSCs) using standard culture systems without the loss of their stem cell properties suggests that a critical feature of their microenvironment necessary for retention of stem cell properties is absent in these culture systems. We report here the reconstitution of a native extracellular matrix (ECM) made by human marrow cells ex vivo, which consists of at least collagen types I and III, fibronectin, small leucine-rich proteoglycans such as biglycan and decorin, and major components of basement membrane such as the large molecular weight proteoglycan perlecan and laminin. Expansion of human MSCs on this ECM strongly promoted their proliferation, retained their stem cell properties with a low level of reactive oxygen species (ROS), and substantially increased their response to BMP-2. The quality of the expanded cells following each passage was further tested by an in vivo transplantation assay. The results showed that MSCs expanded on the ECM for multiple passages still retained the same capacity for skeletogenesis. In contrast, the bone formation capacity of cells expanded on plastic was dramatically diminished after 6-7 passages. These findings suggest that the marrow stromal cell-derived ECM is a promising matrix for expanding largescale highly functional MSCs for eventualuse in stem cell-based therapy. Moreover, this system should also be invaluable for establishment of a unique tissue-specific ECM, which will facilitate control of the fate of MSCs for therapeutic applications.
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Affiliation(s)
- Yanlai Lai
- Department of Restorative Dentistry, Division of Biomaterials, The University of Texas Health Science Center at San Antonio , San Antonio, TX 78229-3900, USA
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Abstract
AIMS Thiazolidinediones (TZDs) are associated with a higher risk of bone fracture in women compared with men. The aim of the present study was to investigate whether TZDs could influence osteocyte behaviour and contribute to the skeletal phenotype observed in TZD-treated patients. METHODS The murine MLO-Y4 cell line was used as a source of osteocytes. These cells were cultured for 24 h with 0, 10(-8) m, 10(-7) m, 10(-6) m, 10(-5) m or 10(-4) m of pioglitazone, rosiglitazone or troglitazone in the presence or absence of 17beta-oestradiol. The extent of osteocyte apoptosis was assessed, as was the expression of the bone formation inhibitor sclerostin and receptor activator for nuclear factor kappaB ligand (RANKL) also. RESULTS In the absence of 17beta-oestradiol, pioglitazone, rosiglitazone and troglitazone induced osteocyte apoptosis dose-dependently even at the lowest concentration of 10(-8) m. Furthermore, the expression of sclerostin but not RANKL was significantly increased in TZD-treated cultures compared with untreated cultures. The presence of 17beta-oestradiol significantly reduced TZD-induced osteocyte apoptosis and also sclerostin up-regulation. CONCLUSIONS These findings therefore raise the potential concern of using TZDs in post-menopausal women where the lack of oestrogen would not prevent osteocyte apoptosis and sclerostin up-regulation and may aggravate the reduction in bone mass in these patients.
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Affiliation(s)
- G Mabilleau
- Nuffield Department of Orthopaedics, Institute of Musculoskeletal Sciences, University of Oxford, Oxford, UK.
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36
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Abstract
Osteocytes are derived from osteoblasts and make up over 90% of the cells in bone. However, the mechanisms that control the differentiation of osteoblasts into osteocytes embedded in bone matrix are not well understood. With the recent developments of transgenic models for manipulating gene expression in osteocytes and of transgenic mice carrying lineage reporters for osteoblasts and osteocytes, unprecedented new insights are becoming possible. In this article we review recent advances, such as comparative gene and protein expression studies, that are delineating the changes in gene and protein expression that accompany osteocyte differentiation. We also review recent studies in which time-lapse dynamic imaging approaches have been used to visualize osteoblast and osteocyte populations within bone. These approaches reveal the key role of cell motility in bone cell function and highlight the dynamic nature of mineralized tissues. Changes in motile properties of the cell may be key in the transition from osteoblast to osteocyte, as reflected in the altered expression of many molecules involved in cytoskeletal function.
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Affiliation(s)
- Sarah L Dallas
- Department of Oral Biology, School of Dentistry, University of Missouri, Kansas City, Missouri, USA.
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Kalogeropoulos M, Varanasi SS, Olstad OK, Sanderson P, Gautvik VT, Reppe S, Francis RM, Gautvik KM, Birch MA, Datta HK. Zic1 transcription factor in bone: neural developmental protein regulates mechanotransduction in osteocytes. FASEB J 2010; 24:2893-903. [DOI: 10.1096/fj.09-148908] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Michail Kalogeropoulos
- Musculoskeletal Research GroupInstitute of Cellular MedicineThe Medical School Newcastle upon Tyne UK
| | - Satya S. Varanasi
- Musculoskeletal Research GroupInstitute of Cellular MedicineThe Medical School Newcastle upon Tyne UK
| | - Ole K. Olstad
- Department of Clinical ChemistryOslo University Hospital Ullevaal Oslo Norway
| | - Paul Sanderson
- Department of Orthopaedic SurgeryThe Newcastle upon Tyne NHS Foundation Trust Hospitals Newcastle upon Tyne UK
| | - Vigdis T. Gautvik
- Department of Clinical ChemistryLovisenberg Deacon Hospital Oslo Norway
| | - Sjur Reppe
- Department of Clinical ChemistryLovisenberg Deacon Hospital Oslo Norway
| | - Roger M. Francis
- Institute for Ageing and HealthNewcastle University Newcastle upon Tyne UK
| | - Kaare M. Gautvik
- Department of Clinical ChemistryOslo University Hospital Ullevaal Oslo Norway
- Department of Clinical ChemistryLovisenberg Deacon Hospital Oslo Norway
- Institute of Basic Medical SciencesUniversity of Oslo Oslo Norway
| | - Mark A. Birch
- Musculoskeletal Research GroupInstitute of Cellular MedicineThe Medical School Newcastle upon Tyne UK
| | - Harish K. Datta
- Musculoskeletal Research GroupInstitute of Cellular MedicineThe Medical School Newcastle upon Tyne UK
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Paic F, Igwe JC, Ravi N, Kronenberg MS, Franceschetti T, Harrington P, Kuo L, Shin DG, Rowe DW, Harris SE, Kalajzic I. Identification of differentially expressed genes between osteoblasts and osteocytes. Bone 2009; 45:682-92. [PMID: 19539797 PMCID: PMC2731004 DOI: 10.1016/j.bone.2009.06.010] [Citation(s) in RCA: 187] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 06/03/2009] [Accepted: 06/04/2009] [Indexed: 11/17/2022]
Abstract
Osteocytes represent the most abundant cellular component of mammalian bones with important functions in bone mass maintenance and remodeling. To elucidate the differential gene expression between osteoblasts and osteocytes we completed a comprehensive analysis of their gene profiles. Selective identification of these two mature populations was achieved by utilization of visual markers of bone lineage cells. We have utilized dual GFP reporter mice in which osteocytes are expressing GFP (topaz) directed by the DMP1 promoter, while osteoblasts are identified by expression of GFP (cyan) driven by 2.3 kb of the Col1a1 promoter. Histological analysis of 7-day-old neonatal calvaria confirmed the expression pattern of DMP1GFP in osteocytes and Col2.3 in osteoblasts and osteocytes. To isolate distinct populations of cells we utilized fluorescent activated cell sorting (FACS). Cell suspensions were subjected to RNA extraction, in vitro transcription and labeling of cDNA and gene expression was analyzed using the Illumina WG-6v1 BeadChip. Following normalization of raw data from four biological replicates, 3444 genes were called present in all three sorted cell populations: GFP negative, Col2.3cyan(+) (osteoblasts), and DMP1topaz(+) (preosteocytes and osteocytes). We present the genes that showed in excess of a 2-fold change for gene expression between DMP1topaz(+) and Col2.3cyan(+) cells. The selected genes were classified and grouped according to their associated gene ontology terms. Genes clustered to osteogenesis and skeletal development such as Bmp4, Bmp8a, Dmp1, Enpp1, Phex and Ank were highly expressed in DMP1topaz(+)cells. Most of the genes encoding extracellular matrix components and secreted proteins had lower expression in DMP1topaz(+) cells, while most of the genes encoding plasma membrane proteins were increased. Interestingly a large number of genes associated with muscle development and function and with neuronal phenotype were increased in DMP1topaz(+) cells, indicating some new aspects of osteocyte biology. Although a large number of genes differentially expressed in DMP1topaz(+) and Col2.3cyan(+) cells in our study have already been assigned to bone development and physiology, for most of them we still lack any substantial data. Therefore, isolation of osteocyte and osteoblast cell populations and their subsequent microarray analysis allowed us to identify a number or genes and pathways with potential roles in regulation of bone mass.
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Affiliation(s)
- Frane Paic
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, Connecticut, USA
- Department of Biology, School of Medicine, Zagreb, Croatia
| | - John C. Igwe
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Nori Ravi
- Department of Computer Science, University of Connecticut, Storrs, Connecticut, USA
| | - Mark S. Kronenberg
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Tiziana Franceschetti
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Patrick Harrington
- Dept. of Statistics, University of Connecticut, Storrs, Connecticut, USA
| | - Lynn Kuo
- Dept. of Statistics, University of Connecticut, Storrs, Connecticut, USA
| | - Don-Guk Shin
- Department of Computer Science, University of Connecticut, Storrs, Connecticut, USA
| | - David W. Rowe
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, Connecticut, USA
| | | | - Ivo Kalajzic
- Department of Reconstructive Sciences, University of Connecticut Health Center, Farmington, Connecticut, USA
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Kanaji A, Caicedo MS, Virdi AS, Sumner DR, Hallab NJ, Sena K. Co-Cr-Mo alloy particles induce tumor necrosis factor alpha production in MLO-Y4 osteocytes: a role for osteocytes in particle-induced inflammation. Bone 2009; 45:528-33. [PMID: 19497395 PMCID: PMC2725206 DOI: 10.1016/j.bone.2009.05.020] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 05/26/2009] [Accepted: 05/26/2009] [Indexed: 01/12/2023]
Abstract
Wear debris-induced osteolysis is purportedly the limiting problem affecting the long term results of joint arthroplasty. Pathogenic effects of wear debris in peri-implant cells such as macrophages, osteoblasts and osteoclasts have been well studied. In contrast, the effects of wear debris on osteocytes, which make up over 90% of all bone cells, remain unknown. We hypothesized that metal implant debris can induce the pro-inflammatory response in osteocytes. This study demonstrated the effects of cobalt-chromium-molybdenum alloy (Co-Cr-Mo) particles on a well-characterized MLO-Y4 osteocyte cell line. Co-Cr-Mo alloy particle treatment significantly (p<0.05) up-regulated tumor necrosis factor alpha (TNFalpha) gene expression after 3 and 6 h and TNFalpha protein production after 24 h, but down-regulated interleukin-6 (IL-6) gene expression after 6 h. Co-Cr-Mo alloy particle treatment also induced osteocyte apoptosis after 24 h. This apoptotic effect was partially (40%) dependent on TNFalpha. Therefore, our results suggest that osteocytes play a role in particle-induced inflammation and bone resorption following total joint arthroplasty by inducing pro-inflammatory cytokines and inducing osteocyte apoptosis.
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Affiliation(s)
- Arihiko Kanaji
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL, 60612, USA
| | - Marco S. Caicedo
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Amarjit S. Virdi
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL, 60612, USA
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - D. Rick Sumner
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL, 60612, USA
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Nadim J. Hallab
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL, 60612, USA
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA
| | - Kotaro Sena
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL, 60612, USA
- Corresponding author: Department of Anatomy and Cell Biology, Rush University Medical Center, 600 South Paulina Street AF507, Chicago, IL 60612, USA, , Tel: +1-312-942-5501, Fax: +1-312-942-5744
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