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Bolamperti S, Villa I, Rubinacci A. Bone remodeling: an operational process ensuring survival and bone mechanical competence. Bone Res 2022; 10:48. [PMID: 35851054 PMCID: PMC9293977 DOI: 10.1038/s41413-022-00219-8] [Citation(s) in RCA: 72] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 05/02/2022] [Accepted: 05/15/2022] [Indexed: 12/12/2022] Open
Abstract
Bone remodeling replaces old and damaged bone with new bone through a sequence of cellular events occurring on the same surface without any change in bone shape. It was initially thought that the basic multicellular unit (BMU) responsible for bone remodeling consists of osteoclasts and osteoblasts functioning through a hierarchical sequence of events organized into distinct stages. However, recent discoveries have indicated that all bone cells participate in BMU formation by interacting both simultaneously and at different differentiation stages with their progenitors, other cells, and bone matrix constituents. Therefore, bone remodeling is currently considered a physiological outcome of continuous cellular operational processes optimized to confer a survival advantage. Bone remodeling defines the primary activities that BMUs need to perform to renew successfully bone structural units. Hence, this review summarizes the current understanding of bone remodeling and future research directions with the aim of providing a clinically relevant biological background with which to identify targets for therapeutic strategies in osteoporosis.
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Affiliation(s)
- Simona Bolamperti
- Osteoporosis and Bone and Mineral Metabolism Unit, IRCCS San Raffaele Hospital, Via Olgettina 60, 20132, Milano, Italy
| | - Isabella Villa
- Osteoporosis and Bone and Mineral Metabolism Unit, IRCCS San Raffaele Hospital, Via Olgettina 60, 20132, Milano, Italy
| | - Alessandro Rubinacci
- Osteoporosis and Bone and Mineral Metabolism Unit, IRCCS San Raffaele Hospital, Via Olgettina 60, 20132, Milano, Italy.
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Mirzaii-Dizgah MR, Mirzaii-Dizgah MH, Mirzaii-Dizgah I, Karami M, Forogh B. [Translated article] Osteoprotegerin changes in saliva and serum of patients with knee osteoarthritis. Rev Esp Cir Ortop Traumatol (Engl Ed) 2022. [DOI: 10.1016/j.recot.2021.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Mirzaii-Dizgah MR, Mirzaii-Dizgah MH, Mirzaii-Dizgah I, Karami M, Forogh B. Osteoprotegerin changes in saliva and serum of patients with knee osteoarthritis. Rev Esp Cir Ortop Traumatol (Engl Ed) 2021; 66:47-51. [PMID: 34147417 DOI: 10.1016/j.recot.2021.02.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Revised: 02/08/2021] [Accepted: 02/10/2021] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE The scope of this study was to assess salivary and serum osteoprotegerin (OPG) levels in knee osteoarthritis (OA). METHODS Serum and saliva OPG levels of 30 knee OA and 30 matched healthy controls in this cross-sectional study was assessed by ELISA. Knee pain was assessed by WOMAC. Data were analyzed by Student's t-test, Spearman correlation test and ROC. RESULTS The mean serum but not saliva OPG level was lower in knee OA than that of the healthy group. WOMAC negatively correlated with serum OPG (r=-0.501; P=0.000). The serum OPG cutoff value was 237.5pg/ml for the diagnosis of knee OA. CONCLUSIONS As serum OPG was lower in knee OA and negatively correlated with WOMAC, it seems that detection of OPG in serum but not in saliva may be a probable marker to the diagnosis of knee OA. KEY MESSAGES Osteoprotegerin decreases in knee osteoarthritis.
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Affiliation(s)
- M-R Mirzaii-Dizgah
- Student Research Committee, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - M-H Mirzaii-Dizgah
- Student Research Committee, School of Dentistry, Aja University of Medical Sciences, Tehran, Iran
| | - I Mirzaii-Dizgah
- Dep. of Physiology, School of Medicine, Aja University of Medical Sciences, Tehran, Iran.
| | - M Karami
- Dep. of Biochemistry, School of Medicine, Aja University of Medical Sciences, Tehran, Iran
| | - B Forogh
- Dep. of Physical Medicine and Rehabilitation, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
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Ferreira GZ, Zen Filho EV, Rubira-Bullen IRF, Garlet GP, Santos CF, Santos PSDS. Delayed alveolar bone repair and osteonecrosis associated with Zoledronic Acid therapy in rats: macroscopic, microscopic and molecular analysis. J Appl Oral Sci 2020; 28:e20200204. [PMID: 32997086 PMCID: PMC7518245 DOI: 10.1590/1678-7757-2020-0204] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 07/14/2020] [Indexed: 12/16/2022] Open
Abstract
Objective This study aims to evaluate bone repair and the development of the medication related osteonecrosis of the jaw (MRONJ) associated with the use of zoledronic acid in Wistar rats. Methodology 48 male Wistar rats were divided into four groups: ZA, treated with intraperitoneal zoledronic acid, 0.6 mg/kg every 28 days, totaling five doses; control (C), treated with 0.9% sodium chloride; ZA-surgical (SZA) and C-surgical (SC), submitted to extraction of the right upper molars 45 days after the first application. Alveolar bone repair was evaluated by macroscopic and histological analysis. Protein expression evaluations were performed by qPCR. Results Macroscopic evaluation showed that 91.66% (11) of the animals in the SZA group and 41.66% (5) from the SC group presented solution of epithelium continuity (P<0.05). All animals in the SZA group and none in the SC group had bone sequestration. The area of osteonecrosis was higher in the SZA group than in the SC group (P<0.05). In molecular evaluation, the SZA group presented changes in the expression of markers for osteoclasts, with increased RANK and RANKL, and a decrease in OPG. Conclusion The results highlighted strong and evident interference of zoledronic acid in bone repair of the socket, causing osteonecrosis and delayed bone remodeling.
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Affiliation(s)
- Gustavo Zanna Ferreira
- UniCesumar - Departamento de Odontologia, Maringá, PR, Brasil; Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Cirurgia, Estomatologia, Patologia e Radiologia, Bauru, SP, Brasil
| | | | - Izabel Regina Fisher Rubira-Bullen
- Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Cirurgia, Estomatologia, Patologia e Radiologia, Bauru, SP, Brasil
| | - Gustavo Pompermaier Garlet
- Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Ciências Biológicas, Bauru, SP, Brasil
| | - Carlos Ferreira Santos
- Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Ciências Biológicas, Bauru, SP, Brasil
| | - Paulo Sérgio da Silva Santos
- Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Cirurgia, Estomatologia, Patologia e Radiologia, Bauru, SP, Brasil
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Ikeda Y, Hasegawa T, Yamamoto T, de Freitas PHL, Oda K, Yamauchi A, Yokoyama A. Histochemical examination on the peri-implant bone with early occlusal loading after the immediate placement into extraction sockets. Histochem Cell Biol 2018; 149:433-47. [DOI: 10.1007/s00418-018-1644-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2018] [Indexed: 01/20/2023]
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Cui D, Li H, Xu X, Ye L, Zhou X, Zheng L, Zhou Y. Mesenchymal Stem Cells for Cartilage Regeneration of TMJ Osteoarthritis. Stem Cells Int 2017; 2017:5979741. [PMID: 29123550 DOI: 10.1155/2017/5979741] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 09/06/2017] [Indexed: 02/05/2023] Open
Abstract
Temporomandibular joint osteoarthritis (TMJ OA) is a degenerative disease, characterized by progressive cartilage degradation, subchondral bone remodeling, synovitis, and chronic pain. Due to the limited self-healing capacity in condylar cartilage, traditional clinical treatments have limited symptom-modifying and structure-modifying effects to restore impaired cartilage as well as other TMJ tissues. In recent years, stem cell-based therapy has raised much attention as an alternative approach towards tissue repair and regeneration. Mesenchymal stem cells (MSCs), derived from the bone marrow, synovium, and even umbilical cord, play a role as seed cells for the cartilage regeneration of TMJ OA. MSCs possess multilineage differentiation potential, including chondrogenic differentiation as well as osteogenic differentiation. In addition, the trophic modulations of MSCs exert anti-inflammatory and immunomodulatory effects under aberrant conditions. Furthermore, MSCs combined with appropriate scaffolds can form cartilaginous or even osseous compartments to repair damaged tissue and impaired function of TMJ. In this review, we will briefly discuss the pathogenesis of cartilage degeneration in TMJ OA and emphasize the potential sources of MSCs and novel approaches for the cartilage regeneration of TMJ OA, particularly focusing on the MSC-based therapy and tissue engineering.
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Zeng JZ, Wang ZZ, Ma LF, Meng H, Yu HM, Cheng WH, Zhang YK, Guo A. Increased receptor activator of nuclear factor κβ ligand/osteoprotegerin ratio exacerbates cartilage destruction in osteoarthritis in vitro. Exp Ther Med 2016; 12:2778-2782. [PMID: 27698783 DOI: 10.3892/etm.2016.3638] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 07/28/2016] [Indexed: 12/12/2022] Open
Abstract
Osteoarthritis (OA) is a degenerative joint disease characterized by progressive cartilage destruction, matrix degradation and bony changes. Subchondral bone alterations in osteoarthritis are associated with cartilage destruction. It has previously been demonstrated that osteoprotegerin (OPG) and receptor activator of nuclear factor κβ ligand (RANKL) mediate this process. The RANKL/OPG ratio is altered in OA chondrocytes compared with normal chondrocytes. In the pathogenesis of OA, abnormal expression levels of matrix metalloproteinase-13 (MMP-13) are secreted by chondrocytes has a vital role in the progression of cartilage erosion. In the present study, the effect of various RANKL/OPG ratios on MMP-13 expression levels was investigated in interleukin-1β-stimulated SW1353 human chondrosarcoma cells. Cell viability was assessed by MTT assay and MMP-13 mRNA and protein expression levels were analyzed by quantitative reverse-transcription-quantitative polymerase chain reaction, ELISA and western blot analyses, respectively. The results demonstrated that an increase in MMP-13 mRNA and protein expression levels was observed with increasing RANKL/OPG ratio. These findings suggest that this mechanism may be used as a novel therapeutic strategy against OA.
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Affiliation(s)
- Ji-Zhou Zeng
- Department of Orthopedics, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, P.R. China; Department of Orthopedics, Beijing Luhe Hospital, Capital Medical University, Beijing 101149, P.R. China
| | - Zhen-Zhong Wang
- Department of Orthopedics, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, P.R. China
| | - Li-Feng Ma
- Department of Orthopedics, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, P.R. China
| | - Hai Meng
- Department of Orthopedics, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, P.R. China
| | - Hao-Miao Yu
- Department of Orthopedics, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, P.R. China
| | - Wen-Hao Cheng
- Department of Orthopedics, Beijing Luhe Hospital, Capital Medical University, Beijing 101149, P.R. China
| | - Ya-Kui Zhang
- Department of Orthopedics, Beijing Luhe Hospital, Capital Medical University, Beijing 101149, P.R. China
| | - Ai Guo
- Department of Orthopedics, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, P.R. China
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Kuang B, Dai J, Wang QY, Song R, Jiao K, Zhang J, Tian XG, Duan YZ, Wang MQ. Combined degenerative and regenerative remodeling responses of the mandibular condyle to experimentally induced disordered occlusion. Am J Orthod Dentofacial Orthop 2013; 143:69-76. [PMID: 23273362 DOI: 10.1016/j.ajodo.2012.08.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 08/01/2012] [Accepted: 08/01/2012] [Indexed: 12/28/2022]
Abstract
INTRODUCTION The purposes of this research were to investigate the long-term responses of mandibular condylar cartilage to experimentally induced disordered occlusion and to evaluate changes in the expression of the SDF-1/CXCR4 axis. METHODS Experimentally induced disordered occlusions were created in 8-week-old female Sprague-Dawley rats by orthodontic methods. After 24 weeks, remodeling of the mandibular condylar cartilage was assessed by hematoxylin and eosin staining. Protein and mRNA expression of SDF-1, CXCR4, MMP9, IL6, OPG, and RANKL were investigated by means of immunohistochemical staining and real-time polymerase chain reaction. RESULTS Obvious cartilage degenerative remodeling responses were observed; they appeared as uneven distributions of cellular disposition, loss of cartilage surface integrity, and cell-free areas. Regenerative responses presenting as thickening of the whole and the calcified cartilage layers in the experimental group were also observed. Compared with the age-matched controls, the protein and mRNA levels of SDF-1, CXCR4, MMP9, IL6, and OPG, but not RANKL, were increased in the experimental group (all, P <0.05). In addition, the mRNA level of RANKL/OPG showed a decreasing trend in the experimental group compared with the age-matched controls (P = 0.052). CONCLUSIONS This study demonstrated that long-term experimentally induced disordered occlusion leads to a combined response in degeneration and regeneration of mandibular cartilage, accompanied by active interaction of the SDF-1/CXCR4 axis and local upregulation of MMP9, IL6, and OPG.
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Hou JM, Xue Y, Lin QM. Bovine lactoferrin improves bone mass and microstructure in ovariectomized rats via OPG/RANKL/RANK pathway. Acta Pharmacol Sin 2012; 33:1277-84. [PMID: 22902986 DOI: 10.1038/aps.2012.83] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM Lactoferrin (LF), an 80-kDa iron-binding glycoprotein, is a pleiotropic factor found in colostrum, milk, saliva and epithelial cells of the exocrine glands. The aim of this study was to evaluate the effects of LF on the bones in ovariectomized (Ovx) rats and to identify the pathways that mediate the anabolic action of LF on the bones. METHODS Female Sprague-Dawley rats (6-month-old) underwent ovariectomy, and were treated with different doses of LF (10, 100, 1000, and 2000 mg·kg(-1)·d(-1), po) or with 7β-estradiol (0.1 mg·kg(-1), im, each week) as the positive control. By the end of 6 month-treatments, the bone mass and microstructure in the rats were scanned by micro-computed tomography (micro-CT), and the bone metabolism was evaluated with specific markers, and the mRNA levels of osteoprotegerin (OPG) and the receptor-activator of nuclear factor κB ligand (RANKL) in femur were measured using qRT-PCR. RESULTS LF treatment dose-dependently elevated the bone volume (BV/TV), trabecular thickness (TbTh) and trabecular number (TbN), and reduced the trabecular separation (TbSp) in Ovx rats. Furthermore, higher doses of LF (1000 and 2000 mg·kg(-1)·d(-1)) significantly increased the bone mineral density (BMD) compared with the untreated Ovx rats. The higher doses of LF also significantly increased the serum levels of OC and BALP, and decreased the serum levels of β-CTx and NTX. LF treatment significantly increased the OPG mRNA levels, and suppressed the RANKL mRNA levels, and the RANKL/OPG mRNA ratio in Ovx rats. CONCLUSION Oral administration of LF preserves the bone mass and improves the bone microarchitecture. LF enhances bone formation, reduces bone resorption, and decreases bone mass loss, possibly through the regulation of OPG/RANKL/RANK pathway.
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Nagata M, Hoshina H, Li M, Arasawa M, Uematsu K, Ogawa S, Yamada K, Kawase T, Suzuki K, Ogose A, Fuse I, Okuda K, Uoshima K, Nakata K, Yoshie H, Takagi R. A clinical study of alveolar bone tissue engineering with cultured autogenous periosteal cells: coordinated activation of bone formation and resorption. Bone 2012; 50:1123-9. [PMID: 22406494 DOI: 10.1016/j.bone.2012.02.631] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 02/16/2012] [Accepted: 02/23/2012] [Indexed: 11/18/2022]
Abstract
In ongoing clinical research into the use of cultured autogenous periosteal cells (CAPCs) in alveolar bone regeneration, CAPCs were grafted into 33 sites (15 for alveolar ridge augmentation and 18 for maxillary sinus lift) in 25 cases. CAPCs were cultured for 6weeks, mixed with particulate autogenous bone and platelet-rich plasma, and then grafted into the sites. Clinical outcomes were determined from high-resolution three-dimensional computed tomography (3D-CT) images and histological findings. No serious adverse events were attributable to the use of grafted CAPCs. Bone regeneration was satisfactory even in cases of advanced atrophy of the alveolar process. Bone biopsy after bone grafting with CAPCs revealed prominent recruitment of osteoblasts and osteoclasts accompanied by angiogenesis around the regenerated bone. 3D-CT imaging suggested that remodeling of the grafted autogenous cortical bone particles was faster in bone grafting with CAPCs than in conventional bone grafting. The use of CAPCs offers cell-based bone regeneration therapy, affording complex bone regeneration across a wide area, and thus expanding the indications for dental implants. Also, it enables the content of particulate autogenous bone in the graft material to be reduced to as low as 40%, making the procedure less invasive, or enabling larger amounts of graft materials to be prepared. It may also be possible to dispense with the use of autogenous bone altogether in the future. The results suggest that CAPC grafting induces bone remodeling, thereby enhancing osseointegration and consequently reducing postoperative waiting time after dental implant placement.
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Affiliation(s)
- Masaki Nagata
- Department of Oral and Maxillofacial Surgery, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata 951-8514, Japan.
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Furugaki K, Moriya Y, Iwai T, Yorozu K, Yanagisawa M, Kondoh K, Fujimoto-Ohuchi K, Mori K. Erlotinib inhibits osteolytic bone invasion of human non-small-cell lung cancer cell line NCI-H292. Clin Exp Metastasis 2011; 28:649-59. [PMID: 21688034 PMCID: PMC3198194 DOI: 10.1007/s10585-011-9398-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 05/31/2011] [Indexed: 02/02/2023]
Abstract
Previous preclinical and clinical findings have suggested a potential role of epidermal growth factor receptor (EGFR) in osteoclast differentiation and the pathogenesis of bone metastasis in cancer. In this study, we investigated the effect of erlotinib, an orally active EGFR tyrosine kinase inhibitor (TKI), on the bone invasion of human non-small-cell lung cancer (NSCLC) cell line NCI-H292. First, we established a novel osteolytic bone invasion model of NCI-H292 cells which was made by inoculating cancer cells into the tibia of scid mice. In this model, NCI-H292 cells markedly activated osteoclasts in tibia, which resulted in osteolytic bone destruction. Erlotinib treatment suppressed osteoclast activation to the basal level through suppressing receptor activator of NF-κB ligand (RANKL) expression in osteoblast/stromal cell at the bone metastatic sites, which leads to inhibition of osteolytic bone destruction caused by NCI-H292 cells. Erlotinib inhibited the proliferation of NCI-H292 cells in in vitro. Erlotinib suppressed the production of osteolytic factors, such as parathyroid hormone-related protein (PTHrP), IL-8, IL-11 and vascular endothelial growth factor (VEGF) in NCI-H292 cells. Furthermore, erlotinib also inhibited osteoblast/stromal cell proliferation in vitro and the development of osteoclasts induced by RANKL in vitro. In conclusion, erlotinib inhibits tumor-induced osteolytic invasion in bone metastasis by suppressing osteoclast activation through inhibiting tumor growth at the bone metastatic sites, osteolytic factor production in tumor cells, osteoblast/stromal cell proliferation and osteoclast differentiation from mouse bone marrow cells.
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Affiliation(s)
- Koh Furugaki
- Product Research Department, Kamakura Research Laboratories, Chugai Pharmaceutical Co., Ltd., Kajiwara, Kamakura, Kanagawa, Japan
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Masuki H, Li M, Hasegawa T, Suzuki R, Ying G, Zhusheng L, Oda K, Yamamoto T, Kawanami M, Amizuka N. Immunolocalization of DMP1 and sclerostin in the epiphyseal trabecule and diaphyseal cortical bone of osteoprotegerin deficient mice. Biomed Res 2011; 31:307-18. [PMID: 21079361 DOI: 10.2220/biomedres.31.307] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In order to define the osteocytic function in accelerated bone remodeling, we examined the distribution of the osteocytic lacunar-canalicular system (OLCS) and osteocyte-secreting molecules--dentin matrix protein (DMP) 1 and sclerostin--in the epiphyses and cortical bones of osteoprotegerin deficient (OPG(-/-)) mice. Silver impregnation visualized a well-arranged OLCS in the wild-type epiphyses and cortical bone, whereas OPG(-/-) mice had an irregular OLCS in the epiphyses, but well-arranged canaliculi in the cortical bone. DMP1-positive osteocytes were evenly distributed throughout the wild-type epiphyses and cortical bone, as well as the OPG(-/-) cortical bone. However, OPG(-/-) epiphyses revealed weak DMP1-immunoreactivity. Thus, osteocytes appear to synthesize more DMP1 as the OLCS becomes regular. In contrast, sclerostin-immunoreactivity was significantly diminished in the OPG(-/-) epiphyses and cortical bone. In OPG(-/-) epiphyses and cortical bone, triple staining demonstrated few sclerostin-positive osteocytes in the periphery of a thick cell layer of alkaline phosphatase-positive osteoblasts and many tartrate resistant acid phosphatase-positive osteoclasts. Summarizing, the regular distribution of OLCS may affect DMP1 synthesis, while the cellular activities of osteoclasts and osteoblasts rather than the regularity of OLCS may ultimately influence sclerostin synthesis.
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Affiliation(s)
- Hideo Masuki
- Department of Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
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Upton AR, Holding CA, Dharmapatni AA, Haynes DR. The expression of RANKL and OPG in the various grades of osteoarthritic cartilage. Rheumatol Int 2012; 32:535-40. [PMID: 21259010 DOI: 10.1007/s00296-010-1733-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 12/30/2010] [Indexed: 12/21/2022]
Abstract
The objective of the study was to determine whether cartilage expression of the bone regulating molecules receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) varies between the different grades of osteoarthritis (OA). Cartilage samples were obtained from 30 patients undergoing total hip/knee replacement surgery. Tissue sections were stained with Safranin O and graded. Immunohistochemical staining was then performed, and levels of RANKL and OPG expression were assessed using a semi-quantitative scoring system. In addition, levels of mRNA encoding for RANKL and OPG were determined by a relative real-time reverse transcription-polymerase chain reaction technique. We found that expression of RANKL protein, mRNA expression, and the ratio of RANKL: OPG mRNA was greater in grade 2 cartilage in comparison with grade 0 cartilage (P < 0.05). Increased RANKL staining in the grade 2 cartilage was predominantly in the peri-cellular region of the middle and deep zones as well as in the matrix of the superficial zone. OPG mRNA expression was greater in grade 3 cartilage in comparison with grade 0 cartilage (P < 0.05). Cartilage and subchondral bone are in close proximity and soluble proteins produced in the cartilage are likely to move from one compartment to the other. Our finding of increased expression of RANKL in grade 2 OA cartilage might explain the increase in bone turnover reported in the subchondral bone of OA patients. The changes seen in the different grades of tissue may also indicate that this effect occurs during the early stages of OA development.
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Ma H, Turpeinen T, Silvennoinen M, Torvinen S, Rinnankoski-Tuikka R, Kainulainen H, Timonen J, Kujala UM, Rahkila P, Suominen H. Effects of diet-induced obesity and voluntary wheel running on the microstructure of the murine distal femur. Nutr Metab (Lond) 2011; 8:1. [PMID: 21241467 PMCID: PMC3034661 DOI: 10.1186/1743-7075-8-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 01/17/2011] [Indexed: 12/14/2022] Open
Abstract
Background Obesity and osteoporosis, two possibly related conditions, are rapidly expanding health concerns in modern society. Both of them are associated with sedentary life style and nutrition. To investigate the effects of diet-induced obesity and voluntary physical activity we used high resolution micro-computed tomography (μCT) together with peripheral quantitative computed tomography (pQCT) to examine the microstructure of the distal femoral metaphysis in mice. Methods Forty 7-week-old male C57BL/6J mice were assigned to 4 groups: control (C), control + running (CR), high-fat diet (HF), and high-fat diet + running (HFR). After a 21-week intervention, all the mice were sacrificed and the left femur dissected for pQCT and μCT measurements. Results The mice fed the high-fat diet showed a significant weight gain (over 70% for HF and 60% for HFR), with increased epididymal fat pad mass and impaired insulin sensitivity. These obese mice had significantly higher trabecular connectivity density, volume, number, thickness, area and mass, and smaller trabecular separation. At the whole bone level, they had larger bone circumference and cross-sectional area and higher density-weighted maximal, minimal, and polar moments of inertia. Voluntary wheel running decreased all the cortical bone parameters, but increased the trabecular mineral density, and decreased the pattern factor and structure model index towards a more plate-like structure. Conclusions The results suggest that in mice the femur adapts to obesity by improving bone strength both at the whole bone and micro-structural level. Adaptation to running exercise manifests itself in increased trabecular density and improved 3D structure, but in a limited overall bone growth
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Affiliation(s)
- Hongqiang Ma
- Department of Health Sciences, University of Jyväskylä, Finland.
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Shoji S, Tabuchi M, Miyazawa K, Yabumoto T, Tanaka M, Kadota M, Maeda H, Goto S. Bisphosphonate inhibits bone turnover in OPG(-/-) mice via a depressive effect on both osteoclasts and osteoblasts. Calcif Tissue Int 2010; 87:181-92. [PMID: 20549197 DOI: 10.1007/s00223-010-9384-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 05/20/2010] [Indexed: 10/19/2022]
Abstract
Osteoclast differentiation and functioning are strictly controlled by RANKL expressed on osteoblast membrane surfaces, but whether osteoclasts exert control over osteoblasts remains unclear. In the present study, we examined the effect of an osteoclast inhibitor, a bisphosphonate (BP), on the response of maxillary bone to mechanical stress in a high-turnover osteoporosis model (OPG(-/-) mice, a model of juvenile Paget disease). Mechanical stress was induced by use of orthodontic elastics to move the maxillary first molar. BP was administered once per day beginning 5 days before elastic insertion. Relative to wild type (WT), in the OPG(-/-) mice tooth movement distance was greater, resorption of the interradicular septum occurred to a greater extent, the osteoclast count was higher, and serum alkaline phosphatase (ALP) was higher. However, administration of BP to OPG(-/-) mice reduced tooth movement distance, increased bone volume at the interradicular septum, decreased the osteoclast count, and reduced serum ALP. BP administration also caused a temporal shift in peak Runx2 staining in OPG(-/-) mice, such that the overall staining time course was similar to that observed for WT mice. We conclude that BP administration not only inhibited osteoclast activity in OPG(-/-) mice but also systemically and locally inhibited osteoblast activity. It is possible that osteoclasts are able to exert some negative control over osteoblasts.
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Affiliation(s)
- Satsuki Shoji
- Department of Orthodontics, School of Dentistry, Aichi-Gakuin University, 2-11, Suemori-Dori, Chikusa-Ku, Nagoya 464-8651, Japan.
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Narimatsu K, Li M, de Freitas PHL, Sultana S, Ubaidus S, Kojima T, Zhucheng L, Ying G, Suzuki R, Yamamoto T, Oda K, Amizuka N. Ultrastructural observation on cells meeting the histological criteria for preosteoblasts--a study in the mouse tibial metaphysis. J Electron Microsc (Tokyo) 2010; 59:427-436. [PMID: 20504799 DOI: 10.1093/jmicro/dfq021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Preosteoblasts are currently defined as the precursors of mature osteoblasts. These cells are morphologically diverse and may represent a continuum during osteoblast differentiation. We have attempted to categorize the different preosteoblastic phenotypes in vivo by examining bone cells expressing the runt-related transcription factor 2, alkaline phosphatase and BrdU incorporation - histological traits of a preosteoblast - under transmission electron microscopy (TEM). TEM observations demonstrated, at least, in part two preosteoblastic subtypes: (i) a cell rich in cisterns of rough endoplasmic reticulum (rER) with vesicles and vacuoles and (ii) a subtype featuring extended cytoplasmic processes that connect with distant cells, with a small amount of scattered cisterns of rER and with many vesicles and vacuoles. ER-rich cells, whose cellular machinery is similar to that of an osteoblast, were often seen adjacent to mature osteoblasts, and therefore, may be ready for terminal differentiation. In contrast, ER-poor and vesicle-rich cells extended their cytoplasmic processes to mature osteoblasts and, frequently, to bone-resorbing osteoclasts. The abundant vesicles and vacuoles identified in this cell type indicate that this cell is involved in vesicular transport rather than matrix synthesis activity. In summary, our study verified the morphological diversity and the ultrastructural properties of osteoblastic cells in vivo.
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Ubaidus S, Li M, Sultana S, de Freitas PHL, Oda K, Maeda T, Takagi R, Amizuka N. FGF23 is mainly synthesized by osteocytes in the regularly distributed osteocytic lacunar canalicular system established after physiological bone remodeling. J Electron Microsc (Tokyo) 2009; 58:381-392. [PMID: 19549991 DOI: 10.1093/jmicro/dfp032] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
This study aimed to evaluate whether the immunolocalization of fibroblast growth factor (FGF) 23 and dentin matrix protein 1 (DMP1) is associated with the spatial regularity of the osteocyte lacunar canalicular system(s) (OLCS). Femora of 12-weeks-old male ICR mice were fixed with 4% paraformaldehyde, decalcified with a 10% EDTA solution and then embedded in paraffin. We have devised a triple staining procedure that combines silver impregnation, alkaline phosphatase (ALPase) immunohistochemistry and tartrate-resistant acid phosphatase (TRAPase) enzyme histochemistry on a single paraffin section. This procedure permitted the visualization of ALPase-positive plump osteoblasts and several TRAPase-positive osteoclasts on those bone matrices featuring irregularly arranged OLCS, and of ALPase-positive bone lining cells on the bone matrix displaying the well-arranged OLCS. As observations proceeded from the metaphysis toward the diaphysis, the endosteal cortical bone displayed narrower bands of calcein labeling, accompanied by increased regularity of the OLCS. This implies that the speed of bone deposition during bone remodeling would affect the regularity of the OLCS. While DMP1 was evenly localized in all regions of the cortical bones, FGF23 was more abundantly localized in osteocytes of cortical bones with regularly arranged OLCS. In cortical bones, the endosteal area featuring regular OLCS exhibited more intense FGF23 immunoreaction when compared to the periosteal region, which tended to display irregular OLCS. In summary, FGF23 appears to be synthesized principally by osteocytes in the regularly distributed OLCS that have been established after bone remodeling.
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Affiliation(s)
- Sobhan Ubaidus
- Center for Transdisciplinary Research, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
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Ota N, Takaishi H, Kosaki N, Takito J, Yoda M, Tohmonda T, Kimura T, Okada Y, Yasuda H, Kawaguchi H, Matsumoto M, Chiba K, Ikegami H, Toyama Y. Accelerated cartilage resorption by chondroclasts during bone fracture healing in osteoprotegerin-deficient mice. Endocrinology 2009; 150:4823-34. [PMID: 19819969 DOI: 10.1210/en.2009-0452] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG), a decoy receptor of RANKL, maintain bone mass by regulating the differentiation of osteoclasts, which are bone-resorbing cells. Endochondral bone ossification and bone fracture healing involve cartilage resorption, a less well-understood process that is needed for replacement of cartilage by bone. Here we describe the role of OPG produced by chondrocytes in chondroclastogenesis. Fracture healing in OPG(-/-) mice showed faster union of the fractured bone, faster resorption of the cartilaginous callus, and an increased number of chondroclasts at the chondroosseous junctions compared with that in wild-type littermates. When a cultured pellet of OPG(-/-) chondrocytes was transplanted beneath the kidney capsule, the pellet recruited many chondroclasts. The pellet showed the ability to induce tartrate-resistant acid phosphatase-positive multinucleated cells from RAW 264.7 cells in vitro. Finally, OPG(-/-) chondrocytes (but not wild-type chondrocytes) cultured with spleen cells induced many tartrate-resistant acid phosphatase-positive multinucleated cells. The expression of RANKL and OPG in chondrocytes was regulated by several osteotropic factors including 1,25-dihydroxyvitamin D(3), PTHrP, IL-1alpha, and TNF-alpha. Thus, local OPG produced by chondrocytes probably controls cartilage resorption as a negative regulator for chondrocyte-dependent chondroclastogenesis.
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Affiliation(s)
- Norikazu Ota
- Department of Orthopaedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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Neves J, Salmon C, Omar N, Narvaes E, Gomes J, Novaes P. Immunolocalization of CSF-1, RANKL and OPG in the enamel-related periodontium of the rat incisor and their implications for alveolar bone remodeling. Arch Oral Biol 2009; 54:651-7. [DOI: 10.1016/j.archoralbio.2009.04.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 03/17/2009] [Accepted: 04/07/2009] [Indexed: 11/26/2022]
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Abstract
Upon the discovery of RANK, RANKL and OPG in the late 1990s, their importance in the maintenance of the skeletal structure and their dramatic role in bone disease were largely unexpected. In recent years the understanding of these proteins, in particular their regulation, has greatly increased. This review aims to bring the interested reader up to date with the latest news and views on the mechanisms controlling bone resorption in normal and pathological conditions.
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Affiliation(s)
- H. L. Wright
- ISTM, Medical School, Keele University at the Leopold Muller Arthritis Research Centre, RJAH Orthopaedic Hospital, Oswestry, Shropshire SY10 7AG UK
| | - H. S. McCarthy
- Charles Salt Research Centre at the RJAH Orthopaedic Hospital, Oswestry, Shropshire SY10 7AG UK
| | - J. Middleton
- ISTM, Medical School, Keele University at the Leopold Muller Arthritis Research Centre, RJAH Orthopaedic Hospital, Oswestry, Shropshire SY10 7AG UK
| | - M. J. Marshall
- Charles Salt Research Centre at the RJAH Orthopaedic Hospital, Oswestry, Shropshire SY10 7AG UK
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Kimura M, Miyazawa K, Tabuchi M, Maeda H, Kameyama Y, Goto S. Bisphosphonate treatment increases the size of the mandibular condyle and normalizes growth of the mandibular ramus in osteoprotegerin-deficient mice. Calcif Tissue Int 2008; 82:137-47. [PMID: 18183447 DOI: 10.1007/s00223-007-9097-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2007] [Accepted: 11/28/2007] [Indexed: 10/22/2022]
Abstract
Osteoprotegerin (OPG) is a novel secreted member of the tumor necrosis factor receptor family which plays a crucial role in negative regulation of osteoclastic bone resorption. OPG-deficient (OPG-/-) mice develop severe osteoporosis caused by significant enhancement of bone resorption by osteoclasts. We investigated the effect of administering bisphosphonate on mandibular growth and development in OPG-/- mice. Eight-week-old male OPG-/- mice and wild-type (WT) mice were administered bisphosphonate (1.25 mg/kg body weight) intraperitoneally once every 3 days for 30 days. All bone formation-related parameters and bone resorption-related parameters were significantly lower in OPG-/- mice with bisphosphonate than in those without bisphosphonate. The volume of the whole condyle and the mandibular length in OPG-/- mice without bisphosphonate were significantly smaller than in WT mice without bisphosphonate. Bisphosphonate treatment of the OPG-/- mice resulted in an increase in the volume of the mandibular condyle and mandibular ramus length. In fact, the mandibular ramus length in OPG-/- mice with bisphosphonate was similar to the length in WT mice without bisphosphonate. Histologically, the surface irregularity of the mandibular condyle that was observed in the OPG-/- mice without bisphosphonate tended to be less marked in the OPG-/- mice with bisphosphonate, and the proportion of the area of the cartilage layer relative to the whole condyle was significantly larger in OPG-/- mice with bisphosphonate than in those without bisphosphonate. In conclusion, bisphosphonate treatment results in an increase in mandibular condylar dimensions and normalization of mandibular ramus growth.
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Affiliation(s)
- Masakazu Kimura
- Department of Orthodontics, School of Dentistry, Aichi-Gakuin University, Chikusa-ku, Nagoya 464-8651, Japan.
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Shimizu S, Asou Y, Itoh S, Chung UI, Kawaguchi H, Shinomiya K, Muneta T. Prevention of cartilage destruction with intraarticular osteoclastogenesis inhibitory factor/osteoprotegerin in a murine model of osteoarthritis. ACTA ACUST UNITED AC 2007; 56:3358-65. [PMID: 17907189 DOI: 10.1002/art.22941] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE To investigate the effect of osteoclastogenesis inhibitory factor/osteoprotegerin (OPG) on chondrocytes in the development of osteoarthritis (OA) in vivo. METHODS To determine the role of endogenous OPG in the progression of OA, OA was surgically induced in OPG+/- mice and their wild-type (WT) littermates. To determine the role of exogenous OPG, knee joints of C57BL/6J mice with surgically induced OA were injected intraarticularly with recombinant human OPG (rHuOPG) or vehicle 5 times a week. All mice were euthanized 4 weeks after OA induction; joints were harvested and evaluated immunohistochemically. RESULTS Although OA changes were induced in both WT and OPG+/- mice, the degenerative changes in the articular cartilage were significantly enhanced in OPG+/- mice. In C57BL/6J mice with surgically induced OA, intraarticular OPG administration protected the articular cartilage from the progression of OA. The Mankin and cartilage destruction scores in OPG-treated animals were approximately 50% of those seen in the control group. Furthermore, OPG administration significantly protected articular cartilage thickness. Findings of the TUNEL assay indicated that rHuOPG prevented chondrocyte apoptosis in joints with surgically induced OA. Results of immunostaining indicated that OPG protein was detected in the synovium and in resident chondrocytes at higher levels in the OPG-treated group than in the control group. CONCLUSION These data indicate that endogenous OPG had a protective effect against the cartilage destruction that occurs during OA progression. Furthermore, direct administration of rHuOPG to articular chondrocytes prevented cartilage destruction in an experimental murine model of OA via prevention of chondrocyte apoptosis.
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Chavassieux P, Seeman E, Delmas PD. Insights into material and structural basis of bone fragility from diseases associated with fractures: how determinants of the biomechanical properties of bone are compromised by disease. Endocr Rev 2007; 28:151-64. [PMID: 17200084 DOI: 10.1210/er.2006-0029] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Minimal trauma fractures in bone diseases are the result of bone fragility. Rather than considering bone fragility as being the result of a reduced amount of bone, we recognize that bone fragility is the result of changes in the material and structural properties of bone. A better understanding of the contribution of each component of the material composition and structure and how these interact to maintain whole bone strength is obtained by the study of metabolic bone diseases. Disorders of collagen (osteogenesis imperfecta and Paget's disease of bone), mineral content, composition and distribution (fluorosis and osteomalacia); diseases of high remodeling (postmenopausal osteoporosis, hyperparathyroidism, and hyperthyroidism) and low remodeling (osteopetrosis, pycnodysostosis); and other diseases (idiopathic male osteoporosis, corticosteroid-induced osteoporosis) produce abnormalities in the material composition and structure that lead to bone fragility. Observations in patients and in animal models provide insights on the biomechanical consequences of these illnesses and the nature of the qualities of bone that determine its strength.
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Affiliation(s)
- P Chavassieux
- Institut National de la Santé et de la Recherche Médicale Unit 831, Pavillon F, Hopital E. Herriot, 69437 Lyon Cedex 08, France
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Hirose S, Li M, Kojima T, de Freitas PHL, Ubaidus S, Oda K, Saito C, Amizuka N. A histological assessment on the distribution of the osteocytic lacunar canalicular system using silver staining. J Bone Miner Metab 2007; 25:374-82. [PMID: 17968489 DOI: 10.1007/s00774-007-0764-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Accepted: 04/13/2007] [Indexed: 10/22/2022]
Abstract
Giving the complexity that characterizes the mechanisms of bone remodeling and the number of events that have to be in absolute harmony for it to occur flawlessly, the postulation that temporospatial distribution of osteocytes and their lacunar canalicular system might influence and be influenced by bone remodeling can be regarded, at least, as feasible. In this study, using Schoen's silver staining, we have examined the distribution of the osteocytic lacunar canalicular system (OLCS) in bones of developing mice. Trabecular bones of 3-day-old, 2-week-old, and 3-week-old mice displayed osteocytic cytoplasmic processes without any perceptible alignment. Also, many plump osteocytes were embedded in the mineralized bone matrix in a disorderly manner. At 4 weeks of age, however, mice bones showed some osteocytic processes that reached the bone surface on a right angle, while other osteocytes displayed the same features seen on 3-week specimens. Samples at 8 weeks of age featured osteocytes with their usual spindle shape, organized so as to parallel the longitudinal axis of trabecular bone. They also extended their cytoplasmic processes perpendicularly to the bone surface. However, several osteocytes immersed in older bone, i.e., a residual mix of cartilage and bone matrices, still showed a random pattern of distribution of their cytoplasmic processes. Up to 12 weeks of age, the majority of the osteocytes became flattened and were shown to be aligned with their long axis paralleling the bone surface. This tendency for such a gradual arrangement was also observed in cortical bones. We have further demonstrated that 8-week-old osteoprotegerin-deficient mice, which demonstrated histological evidence of higher than average bone turnover, revealed a disorganized OLCS. Given the data gathered in this work, the OLCS appears to assume an organized, probably function-related spatial distribution as normal bone remodeling goes on.
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Affiliation(s)
- Satoshi Hirose
- Division of Reconstructive Surgery for Oral and Maxillofacial Region, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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Abstract
Substantial advancements have been made in defining the cells and molecular signals that guide tooth crown morphogenesis and development. As a result, very encouraging progress has been made in regenerating crown tissues by using dental stem cells and recombining epithelial and mesenchymal tissues of specific developmental ages. To date, attempts to regenerate a complete tooth, including the critical periodontal tissues of the tooth root, have not been successful. This may be in part due to a lesser degree of understanding of the events leading to the initiation and development of root and periodontal tissues. Controversies still exist regarding the formation of periodontal tissues, including the origins and contributions of cells, the cues that direct root development, and the potential of these factors to direct regeneration of periodontal tissues when they are lost to disease. In recent years, great strides have been made in beginning to identify and characterize factors contributing to formation of the root and surrounding tissues, that is, cementum, periodontal ligament, and alveolar bone. This review focuses on the most exciting and important developments over the last 5 years toward defining the regulators of tooth root and periodontal tissue development, with special focus on cementogenesis and the potential for applying this knowledge toward developing regenerative therapies. Cells, genes, and proteins regulating root development are reviewed in a question-answer format in order to highlight areas of progress as well as areas of remaining uncertainty that warrant further study.
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Affiliation(s)
- Brian L Foster
- Department of Periodontics, School of Dentistry, University of Washington, Seattle, Washington 98195, USA
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Kanzaki S, Ito M, Takada Y, Ogawa K, Matsuo K. Resorption of auditory ossicles and hearing loss in mice lacking osteoprotegerin. Bone 2006; 39:414-9. [PMID: 16564235 DOI: 10.1016/j.bone.2006.01.155] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2005] [Revised: 01/16/2006] [Accepted: 01/31/2006] [Indexed: 11/26/2022]
Abstract
Bones conduct sound in the middle ear. The three ossicles-the malleus, incus, and stapes-form a chain that transmits vibrations from the tympanic membrane to the oval window of the inner ear. Little is known about bone remodeling events in these ossicles and about potential effects of osteoporosis on hearing loss. Osteoclastic bone resorption is enhanced in Opg(-/-) mice lacking osteoprotegerin, which is a soluble decoy receptor for the osteoclastogenic cytokine RANKL. We asked whether auditory ossicles are resorbed in Opg(-/-) mice, and whether these mice suffer from impaired auditory function. All three ossicles in Opg(-/-) mice showed thinning, especially at the malleal manubrium and incus body. Most notably, unlike in the case in wild-type mice, the junction between the stapes and the otic capsule was fixed in Opg(-/-) mice, and the stapedial footplate was thinner and broader. Radiological analyses revealed that malleal cortical thickness was positively correlated with tibial bone mineral density in Opg(-/-) and control littermate mice. Furthermore, progressive hearing loss was detected in Opg(-/-) mice starting at 6 to 15 weeks of age. These data suggest that osteoprotegerin plays a crucial role in hearing by protecting the auditory ossicles and otic capsule from osteoclastic bone resorption.
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Affiliation(s)
- Sho Kanzaki
- Department of Otolaryngology, School of Medicine, Keio University, 35 Shinanomachi, Tokyo 160-8582, Japan
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Sakakura Y, Tsuruga E, Irie K, Hosokawa Y, Nakamura H, Yajima T. Immunolocalization of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) in Meckel's cartilage compared with developing endochondral bones in mice. J Anat 2006; 207:325-37. [PMID: 16191162 PMCID: PMC1571553 DOI: 10.1111/j.1469-7580.2005.00466.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We examined the immunolocalization of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) in areas of resorption caused by osteoclasts/chondroclasts on embryonic days 14-16 (E14-16) in Meckel's cartilage, and compared the results with those in endochondral bones in mice. Intense RANKL and OPG immunoreactivity was detected in the chondrocytes in Meckel's cartilage. On E15, when the incisor teeth were closest to the middle portion of Meckel's cartilage, tartrate-resistant acid phosphatase (TRAP)-positive cells appeared on the lateral side of the cartilage. Furthermore, the dental follicle showed moderate immunoreactivity for RANKL and OPG, whereas osteoblasts derived from perichondral cells were immunonegative for RANKL and OPG in that area. On E16, cartilage resorption by TRAP-positive cells had progressed at the differential position, and intensely immunoreactive products of RANKL were overlapped on and found to exist next to TRAP-positive cells in the resorption area. In developing metatarsal tissue, OPG immunoreactivity was intense in periosteal osteoblasts, whereas RANKL was only faintly seen in some of the periosteal cells. In epiphyseal chondrocytes of the developing femur, RANKL immunoreactivity was moderate, and OPG scarcely detected. These results indicate a peculiarity of RANKL and OPG immunolocalization in resorption of Meckel's cartilage. Growth of the incisor teeth may be involved in the time- and position-specific resorption of Meckel's cartilage through local regulation of the RANKL/OPG system in dental follicular cells and periosteal osteoblasts, whereas RANKL and OPG in chondrocytes seem to contribute to resorption through regulation of the chondroclast function.
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Affiliation(s)
- Yasunori Sakakura
- Department of Oral Anatomy, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido, Japan.
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Yamazaki H, Sasaki T. Effects of osteoprotegerin administration on osteoclast differentiation and trabecular bone structure in osteoprotegerin-deficient mice. Microscopy (Oxf) 2005; 54:467-77. [PMID: 16339792 DOI: 10.1093/jmicro/dfi066] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Osteoprotegerin (OPG)-deficient mice exhibit severe bone loss including the destruction of growth plate cartilage. Using OPG-deficient mice, we attempted to clarify the differentiation and ultrastructure of osteoclasts located on the destroyed growth plate cartilage and trabecular bone matrix in long bones. In (-/-) homozygous OPG knockout mice, adjacent to the growth plate cartilage, the formation of bone trabeculae without a calcified cartilaginous core resulted in an irregular chondrocyte distribution in the growth plate cartilage. At the metaphyseal ossification center, TRAP-positive osteoclasts showed unusual localization on both type-II collagen-positive cartilage and type-I collagen-positive bone matrix. Osteoclasts located on cartilage matrix lacked a typical ruffled border structure, but formed resorption lacunae. During growth plate cartilage destruction, osteoclasts formed ruffled border structures on bone matrix deposited on the remaining cartilage surfaces. These findings suggest that, in OPG (-/-) mice, osteoclast structure differs, depending on the matrix of either cartilage or bone. Then, we examined the effects of OPG administration on the internal trabecular bone structure and osteoclast differentiation in OPG (-/-) mice. OPG administration to OPG (-/-) mice significantly inhibited trabecular bone loss and maintained the internal trabecular bone structure, but did not reduce the osteoclast number on bone trabeculae. For most osteoclasts, OPG administration caused disappearance or reduction of the ruffled border, but induced neither necrotic nor apoptotic damages. These results suggest that OPG administration is an effective means of maintaining the internal structure and volume of trabecular bone in metabolic bone diseases by inhibition of osteoclastic bone resorption.
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Affiliation(s)
- Hiroko Yamazaki
- Department of Oral Histology, School of Dentistry, Showa University, Shinagawa-ku, Tokyo, Japan
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Amizuka N, Shimomura J, Li M, Nasu M, Maeda T. Histological evaluation for "bone quality" on two mouse models with different bone remodeling. J Bone Miner Metab 2005; 23 Suppl:43-7. [PMID: 15984413 DOI: 10.1007/bf03026322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Norio Amizuka
- Division of Oral Anatomy, Department of Oral Biological Science, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Niigata 951-8514, Japan.
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