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Condi FLDF, Fuchs LFP, Carvalho KC, Baracat EC. Treatment with Raloxifene Induces the Expression of Kisspeptin, Insulin, and Androgen Receptors in Bones of Castrated Adult Female Rats. Rev Bras Ortop 2024; 59:e228-e234. [PMID: 38606141 PMCID: PMC11006519 DOI: 10.1055/s-0044-1779319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 06/26/2023] [Indexed: 04/13/2024] Open
Abstract
Objective To evaluate the effects of estrogen, raloxifene and genistein on the expression of KISS1 (kisspeptin), KISS1R (kisspeptin receptor), AR (androgen receptor) and INSR (insulin receptor) in the bones of ovariectomized rats. Methods Forty-eight adult rats were randomly divided into 6 groups, containing 8 animals each: G1-nonovariectomized control; G2-ovariectomized and treated with conjugated equine estrogens (50 µg/Kg/day); G3-ovariectomized and treated with raloxifene (0.75 mg/kg/day); G4-ovariectomized animal that received soy extract with genistein (300 mg/kg/day); G5-ovariectomized animal that received estrogen and genistein; and G6-ovariectomized animal that received estrogen and raloxifene. Three months after surgery, the castrated animals received the drugs orally daily for 120 days. All animals were sacrificed after this period, by deepening the anesthesia. The left tibia was removed for total RNA extraction and analysis of gene expression of KISS1 , KISS1R , AR and INSR , by quantitative real-time polymerase chain reaction (qRT-PCR). Results KISS1 was not detected in any of the treated groups. KISS1R , INSR and AR showed higher expression in the G3 group ( p < 0.001), while lower levels of transcripts for these genes were observed in G4 and G5. G2 animals showed hypoexpression of the evaluated genes. Conclusion The results indicate that raloxifene, alone or combined with estrogen, was able to induce the expression of genes associated with the recovery of bone tissue homeostasis in ovariectomized rats.
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Affiliation(s)
| | - Luiz Fernando Portugal Fuchs
- Departamento de Ginecologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil
| | - Katia Candido Carvalho
- Laboratório de Ginecologia Estrutural e Molecular (LIM 58), Disciplina de Ginecologia, Departamento de Obstetrícia e Ginecologia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (HCFMUSP), São Paulo, SP, Brasil
| | - Edmund Chada Baracat
- Laboratório de Ginecologia Estrutural e Molecular (LIM 58), Disciplina de Ginecologia, Departamento de Obstetrícia e Ginecologia, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo (HCFMUSP), São Paulo, SP, Brasil
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Ahmadzadeh K, Vanoppen M, Rose CD, Matthys P, Wouters CH. Multinucleated Giant Cells: Current Insights in Phenotype, Biological Activities, and Mechanism of Formation. Front Cell Dev Biol 2022; 10:873226. [PMID: 35478968 PMCID: PMC9035892 DOI: 10.3389/fcell.2022.873226] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 03/17/2022] [Indexed: 12/21/2022] Open
Abstract
Monocytes and macrophages are innate immune cells with diverse functions ranging from phagocytosis of microorganisms to forming a bridge with the adaptive immune system. A lesser-known attribute of macrophages is their ability to fuse with each other to form multinucleated giant cells. Based on their morphology and functional characteristics, there are in general three types of multinucleated giant cells including osteoclasts, foreign body giant cells and Langhans giant cells. Osteoclasts are bone resorbing cells and under physiological conditions they participate in bone remodeling. However, under pathological conditions such as rheumatoid arthritis and osteoporosis, osteoclasts are responsible for bone destruction and bone loss. Foreign body giant cells and Langhans giant cells appear only under pathological conditions. While foreign body giant cells are found in immune reactions against foreign material, including implants, Langhans giant cells are associated with granulomas in infectious and non-infectious diseases. The functionality and fusion mechanism of osteoclasts are being elucidated, however, our knowledge on the functions of foreign body giant cells and Langhans giant cells is limited. In this review, we describe and compare the phenotypic aspects, biological and functional activities of the three types of multinucleated giant cells. Furthermore, we provide an overview of the multinucleation process and highlight key molecules in the different phases of macrophage fusion.
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Affiliation(s)
- Kourosh Ahmadzadeh
- Laboratory of Immunobiology, Department Microbiology and Immunology, Rega Institute, KU Leuven – University of Leuven, Leuven, Belgium
- *Correspondence: Kourosh Ahmadzadeh, ; Carine Helena Wouters,
| | - Margot Vanoppen
- Laboratory of Immunobiology, Department Microbiology and Immunology, Rega Institute, KU Leuven – University of Leuven, Leuven, Belgium
| | - Carlos D. Rose
- Division of Pediatric Rheumatology Nemours Children’s Hospital, Thomas Jefferson University, Philadelphia, PA, United States
| | - Patrick Matthys
- Laboratory of Immunobiology, Department Microbiology and Immunology, Rega Institute, KU Leuven – University of Leuven, Leuven, Belgium
| | - Carine Helena Wouters
- Laboratory of Immunobiology, Department Microbiology and Immunology, Rega Institute, KU Leuven – University of Leuven, Leuven, Belgium
- Division Pediatric Rheumatology, UZ Leuven, Leuven, Belgium
- European Reference Network for Rare Immunodeficiency, Autoinflammatory and Autoimmune Diseases (RITA) at University Hospital Leuven, Leuven, Belgium
- *Correspondence: Kourosh Ahmadzadeh, ; Carine Helena Wouters,
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He B, Zhu Y, Cui H, Sun B, Su T, Wen P. Comparison of Necroptosis With Apoptosis for OVX-Induced Osteoporosis. Front Mol Biosci 2022; 8:790613. [PMID: 35004853 PMCID: PMC8740137 DOI: 10.3389/fmolb.2021.790613] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 11/29/2021] [Indexed: 01/18/2023] Open
Abstract
As one common kind of osteoporosis, postmenopausal osteoporosis (PMOP) is associated with the death and excessive loss of osteocytes. Estrogen deficiency of PMOP can cause osteocyte death by regulating necroptosis and apoptosis, but their roles in POMP have not been compared. In the present study, ovariectomy (OVX)-induced rat and murine long bone osteocyte Y4 (MLO-Y4) cells were used to compare the influence of necroptosis and apoptosis on osteocyte death and bone loss. Benzyloxycarbonyl-Val-Ala-Asp (zVAD) and necrostatin-1 (Nec-1) were used to specifically block cell apoptosis and necroptosis, respectively. OVX rats and MLO-Y4 cells were divided into zVAD group, Nec-1 group, zVAD + Nec-1 group, vehicle, and control group. The tibial plateaus of the rat model were harvested at 8 weeks after OVX and were analyzed by micro–computed tomography, transmission electron microscopy (TEM), the transferase dUTP nick end labeling assay, and western blot. The death of MLO-Y4 was stimulated by TNF-α and was measured by flow cytometry and TEM. The results found that necroptosis and apoptosis were both responsible for the death and excessive loss of osteocytes, as well as bone loss in OVX-induced osteoporosis, and furthermore necroptosis may generate greater impact on the death of osteocytes than apoptosis. Necroptotic death of osteocytes was mainly regulated by the receptor-interacting protein kinase 3 signaling pathway. Collectively, inhibition of necroptosis may produce better efficacy in reducing osteocyte loss than that of apoptosis, and combined blockade of necroptosis and apoptosis provide new insights into preventing and treating PMOP.
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Affiliation(s)
- Bin He
- Department of Spine and Osteopathic Surgery, The First Affiliated Hospital of Hainan Medical University, Haikou, China.,Department of Orthopedics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yongjun Zhu
- Department of Nephrology, The First Affiliated Hospital of Hainan Medical University, Haikou, China
| | - Hongwang Cui
- Department of Spine and Osteopathic Surgery, The First Affiliated Hospital of Hainan Medical University, Haikou, China
| | - Bo Sun
- Department of Spine and Osteopathic Surgery, The First Affiliated Hospital of Hainan Medical University, Haikou, China
| | - Tian Su
- Department of Spine and Osteopathic Surgery, The First Affiliated Hospital of Hainan Medical University, Haikou, China
| | - Peng Wen
- Department of Spine and Osteopathic Surgery, The First Affiliated Hospital of Hainan Medical University, Haikou, China
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da Silva Sasso GR, Florencio-Silva R, Sasso-Cerri E, Gil CD, de Jesus Simões M, Cerri PS. Spatio-temporal immunolocalization of VEGF-A, Runx2, and osterix during the early steps of intramembranous ossification of the alveolar process in rat embryos. Dev Biol 2021; 478:133-143. [PMID: 34245724 DOI: 10.1016/j.ydbio.2021.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 06/10/2021] [Accepted: 07/03/2021] [Indexed: 12/14/2022]
Abstract
Vascular endothelial growth factor A (VEGF-A) is expressed by several cell types and is a crucial factor for angiogenic-osteogenic coupling. However, the immunolocalization of VEGF-A during the early stages of the alveolar process formation remains underexplored. Thus, we analyzed the spatio-temporal immunolocalization of VEGF-A and its relationship with Runt-related transcription factor 2 (Runx2) and osterix (Osx) during the early steps of intramembranous ossification of the alveolar process in rat embryos. Embryo heads (E) of 16, 18 and 20-day-old rats were processed for paraffin embedding. Histomorphometry and immunohistochemistry to detect VEGF-A, Runx2, and Osx (osteoblast differentiation markers) were performed. The volume density of bone tissue including bone cells and blood vessels increased significantly in E18 and E20. Cells showing high VEGF-A immunoreactivity were initially observed within a perivascular niche in the ectomesenchyme; afterwards, these cells were diffusely located near bone formation sites. Runx2-and Osx-immunopositive cells were observed in corresponded regions of cells showing strong VEGF-A immunoreactivity. Although these immunostained cells were observed in all specimens, this immunolocalization pattern was more evident in E16 specimens and gradually decreased in E18 and E20 specimens. Double immunofluorescence labelling showed intracellular co-localization of Osx and VEGF-A in cells surrounding the developing alveolar process, indicating a crucial role of VEGF-A in osteoblast differentiation. Our results showed VEGF-A immunoexpression in osteoblasts and its precursors during the maxillary alveolar process formation of rat embryos. Moreover, the VEGF-A-positive cells located within a perivascular niche at the early stages of the alveolar process development suggest a crosstalk between endothelium and ectomesenchymal cells, reinforcing the angiogenic-osteogenic coupling in this process.
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Affiliation(s)
- Gisela Rodrigues da Silva Sasso
- Universidade Federal de São Paulo - UNIFESP, Escola Paulista de Medicina - EPM, Departamento de Morfologia e Genética, Disciplina de Histologia e Biologia Estrutural, São Paulo, SP, Brazil; Universidade Federal de São Paulo - UNIFESP, Escola Paulista de Medicina - EPM, Departamento de Ginecologia, São Paulo, SP, Brazil
| | - Rinaldo Florencio-Silva
- Universidade Federal de São Paulo - UNIFESP, Escola Paulista de Medicina - EPM, Departamento de Morfologia e Genética, Disciplina de Histologia e Biologia Estrutural, São Paulo, SP, Brazil
| | - Estela Sasso-Cerri
- São Paulo State University (UNESP), School of Dentistry, Araraquara - Department of Morphology, Genetics, Orthodontics and Pediatric Dentistry - Laboratory of Histology and Embryology, Araraquara, SP, Brazil
| | - Cristiane Damas Gil
- Universidade Federal de São Paulo - UNIFESP, Escola Paulista de Medicina - EPM, Departamento de Morfologia e Genética, Disciplina de Histologia e Biologia Estrutural, São Paulo, SP, Brazil
| | - Manuel de Jesus Simões
- Universidade Federal de São Paulo - UNIFESP, Escola Paulista de Medicina - EPM, Departamento de Morfologia e Genética, Disciplina de Histologia e Biologia Estrutural, São Paulo, SP, Brazil
| | - Paulo Sérgio Cerri
- São Paulo State University (UNESP), School of Dentistry, Araraquara - Department of Morphology, Genetics, Orthodontics and Pediatric Dentistry - Laboratory of Histology and Embryology, Araraquara, SP, Brazil.
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Madel MB, Ibáñez L, Wakkach A, de Vries TJ, Teti A, Apparailly F, Blin-Wakkach C. Immune Function and Diversity of Osteoclasts in Normal and Pathological Conditions. Front Immunol 2019; 10:1408. [PMID: 31275328 PMCID: PMC6594198 DOI: 10.3389/fimmu.2019.01408] [Citation(s) in RCA: 118] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 06/04/2019] [Indexed: 12/31/2022] Open
Abstract
Osteoclasts (OCLs) are key players in controlling bone remodeling. Modifications in their differentiation or bone resorbing activity are associated with a number of pathologies ranging from osteopetrosis to osteoporosis, chronic inflammation and cancer, that are all characterized by immunological alterations. Therefore, the 2000s were marked by the emergence of osteoimmunology and by a growing number of studies focused on the control of OCL differentiation and function by the immune system. At the same time, it was discovered that OCLs are much more than bone resorbing cells. As monocytic lineage-derived cells, they belong to a family of cells that displays a wide heterogeneity and plasticity and that is involved in phagocytosis and innate immune responses. However, while OCLs have been extensively studied for their bone resorption capacity, their implication as immune cells was neglected for a long time. In recent years, new evidence pointed out that OCLs play important roles in the modulation of immune responses toward immune suppression or inflammation. They unlocked their capacity to modulate T cell activation, to efficiently process and present antigens as well as their ability to activate T cell responses in an antigen-dependent manner. Moreover, similar to other monocytic lineage cells such as macrophages, monocytes and dendritic cells, OCLs display a phenotypic and functional plasticity participating to their anti-inflammatory or pro-inflammatory effect depending on their cell origin and environment. This review will address this novel vision of the OCL, not only as a phagocyte specialized in bone resorption, but also as innate immune cell participating in the control of immune responses.
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Affiliation(s)
- Maria-Bernadette Madel
- CNRS, Laboratoire de PhysioMédecine Moléculaire, Faculté de Médecine, UMR7370, Nice, France.,Faculé de Médecine, Université Côte d'Azur, Nice, France
| | - Lidia Ibáñez
- Department of Pharmacy, Cardenal Herrera-CEU University, València, Spain
| | - Abdelilah Wakkach
- CNRS, Laboratoire de PhysioMédecine Moléculaire, Faculté de Médecine, UMR7370, Nice, France.,Faculé de Médecine, Université Côte d'Azur, Nice, France
| | - Teun J de Vries
- Department of Periodontology, Academic Centre of Dentistry Amsterdam, University of Amsterdam and Vrije Univeristeit, Amsterdam, Netherlands
| | - Anna Teti
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | | | - Claudine Blin-Wakkach
- CNRS, Laboratoire de PhysioMédecine Moléculaire, Faculté de Médecine, UMR7370, Nice, France.,Faculé de Médecine, Université Côte d'Azur, Nice, France
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6
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Mello ASDS, dos Santos PL, Marquesi A, Queiroz TP, Margonar R, de Souza Faloni AP. Some aspects of bone remodeling around dental implants. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.piro.2015.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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7
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de Pizzol Júnior JP, Sasso-Cerri E, Cerri PS. Apoptosis and reduced microvascular density of the lamina propria during tooth eruption in rats. J Anat 2015; 227:487-96. [PMID: 26228092 DOI: 10.1111/joa.12359] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/24/2015] [Indexed: 12/12/2022] Open
Abstract
During tooth eruption, structural and functional changes must occur in the lamina propria to establish the eruptive pathway. In this study, we evaluate the structural changes that occur during lamina propria degradation and focus these efforts on apoptosis and microvascular density. Fragments of maxilla containing the first molars from 9-, 11-, 13- and 16-day-old rats were fixed, decalcified and embedded in paraffin. The immunohistochemical detection of vascular endothelial growth factor (VEGF), caspase-3 and MAC387 (macrophage marker), and the TUNEL method were applied to the histological molar sections. The numerical density of TUNEL-positive cells and VEGF-positive blood vessel profiles were also obtained. Data were statistically evaluated using a one-way anova with the post-hoc Kruskal-Wallis or Tukey test and a significance level of P ≤ 0.05. Fragments of maxilla were embedded in Araldite for analysis under transmission electron microscopy (TEM). TUNEL-positive structures, fibroblasts with strongly basophilic nuclei and macrophages were observed in the lamina propria at all ages. Using TEM, we identified processes of fibroblasts or macrophages surrounding partially apoptotic cells. We found a high number of apoptotic cells in 11-, 13- and 16-day-old rats. We observed VEGF-positive blood vessel profiles at all ages, but a significant decrease in the numerical density was found in 13- and 16-day-old rats compared with 9-day-old rats. Therefore, the establishment of the eruptive pathway during the mucosal penetration stage depends on cell death by apoptosis, the phagocytic activity of fibroblasts and macrophages, and a decrease in the microvasculature due to vascular cell death. These data point to the importance of vascular rearrangement and vascular neoformation during tooth eruption and the development of oral mucosa.
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Affiliation(s)
| | - Estela Sasso-Cerri
- Dental School - Laboratory of Histology and Embryology, UNESP - São Paulo State University, Araraquara, SP, Brazil
| | - Paulo Sérgio Cerri
- Dental School - Laboratory of Histology and Embryology, UNESP - São Paulo State University, Araraquara, SP, Brazil
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8
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Biology of Bone Tissue: Structure, Function, and Factors That Influence Bone Cells. BIOMED RESEARCH INTERNATIONAL 2015; 2015:421746. [PMID: 26247020 PMCID: PMC4515490 DOI: 10.1155/2015/421746] [Citation(s) in RCA: 880] [Impact Index Per Article: 97.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 04/30/2015] [Accepted: 05/04/2015] [Indexed: 02/06/2023]
Abstract
Bone tissue is continuously remodeled through the concerted actions of bone cells, which include bone resorption by osteoclasts and bone formation by osteoblasts, whereas osteocytes act as mechanosensors and orchestrators of the bone remodeling process. This process is under the control of local (e.g., growth factors and cytokines) and systemic (e.g., calcitonin and estrogens) factors that all together contribute for bone homeostasis. An imbalance between bone resorption and formation can result in bone diseases including osteoporosis. Recently, it has been recognized that, during bone remodeling, there are an intricate communication among bone cells. For instance, the coupling from bone resorption to bone formation is achieved by interaction between osteoclasts and osteoblasts. Moreover, osteocytes produce factors that influence osteoblast and osteoclast activities, whereas osteocyte apoptosis is followed by osteoclastic bone resorption. The increasing knowledge about the structure and functions of bone cells contributed to a better understanding of bone biology. It has been suggested that there is a complex communication between bone cells and other organs, indicating the dynamic nature of bone tissue. In this review, we discuss the current data about the structure and functions of bone cells and the factors that influence bone remodeling.
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McManus A, Utreja A, Chen J, Kalajzic Z, Yang W, Nanda R, Wadhwa S, Uribe F. Evaluation of BSP expression and apoptosis in the periodontal ligament during orthodontic relapse: a preliminary study. Orthod Craniofac Res 2014; 17:239-48. [PMID: 24924469 DOI: 10.1111/ocr.12049] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2014] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To examine the expression of bone sialoprotein (BSP) and apoptosis in an in vivo orthodontic relapse model. MATERIALS AND METHODS Male mice (10-12 weeks old), either transgenic [green fluorescent protein (GFP) driven by the BSP promoter] or wild type, were used in this study. To achieve orthodontic tooth movement (OTM), maxillary right first molars were moved mesially using closed-coil springs. Animals were divided into an OTM group (14 days continuous orthodontic force - 11 animals) or Relapse group (10 days of force application followed by 4 days of relapse - 8 animals). The control group was comprised of the contralateral maxillary molars. The periodontal ligament (PDL) was analyzed in areas of compression and tension for transgenic expression, osteoclast localization, and the presence of apoptotic cells. RESULTS There was a significant decrease in GFP-labeled cells on the compression and tension sides of the PDL in the OTM group compared with control. In the relapse group, GFP-labeled cells were significantly decreased only on the old compression side. Osteoclasts were localized on the compression side of the OTM group, whereas in the Relapse group, they were present on both sides. PDL apoptosis significantly increased on the compression side in OTM and Relapse groups. CONCLUSION Both OTM and Relapse groups exhibited a decreased number of GFP-labeled cells in areas of compression and tension. There was significant PDL apoptosis in regions under compressive forces following OTM and to a lesser extent following relapse.
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Affiliation(s)
- A McManus
- Private Practice, Shrewsbury, MA, USA
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Abstract
Studies from the 1950s and 1960s already recognize the fact that osteocytes, although long living cells, die, as evidenced by accumulation of osteocytic lacunae devoid of cells. More recently, it was demonstrated that these cells die by apoptosis. The rate of osteocyte apoptosis is regulated by the age of the bone, as well as by systemic hormones, local growth factors, cytokines, pharmacological agents, and mechanical forces. Apoptotic osteocytes, in turn, recruit osteoclasts to initiate targeted bone resorption. This results in the removal of "dead" bone and may improve the mechanical properties of the skeleton. However, the molecular regulators of osteocyte survival and targeted bone remodeling are not completely known. In this review, the current knowledge on the molecular mechanism that lead to osteocyte death or survival, and the signals that mediate targeted bone resorption is discussed.
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Affiliation(s)
- Lilian I Plotkin
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS-5035, Indianapolis, IN, USA,
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Bradaschia-Correa V, Casado-Gomez I, Moreira MM, Ferreira LB, Arana-Chavez VE. Immunolocalization of Smad-4 in developing molar roots of alendronate-treated rats. Arch Oral Biol 2013; 58:1744-50. [DOI: 10.1016/j.archoralbio.2013.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 05/04/2013] [Accepted: 06/05/2013] [Indexed: 01/29/2023]
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12
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Reduced RANKL expression impedes osteoclast activation and tooth eruption in alendronate-treated rats. Cell Tissue Res 2013; 353:79-86. [PMID: 23636419 DOI: 10.1007/s00441-013-1623-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 04/01/2013] [Indexed: 10/26/2022]
Abstract
The creation of the eruption pathway requires the resorption of the occlusal alveolar bone by osteoclasts and signaling events between bone and dental follicle are necessary. The aim of the present study has been to evaluate the effect of alendronate on osteoclastogenesis and the expression of the regulator proteins of osteoclast activation, namely RANK, RANKL and OPG, in the bone that covers the first molar germ. Newborn Wistar rats were treated daily with 2.5 mg/kg alendronate for 4, 8, 14, 21 and 28 days, whereas controls received sterile saline solution. At the time points cited, maxillae were fixed, decalcified and processed for light and electron microscopic analysis. TRAP histochemistry was performed on semi-serial sections and the osteoclasts in the occlusal half of the bony crypt surface were counted. TUNEL analysis was carried out on paraffin sections. The occlusal bone that covers the upper first molar was removed in additional 4- and 8-day-old alendronate-treated and control rats in which the expression of RANK, RANKL and OPG was analyzed by SDS-polyacrylamide gel electrophoresis and Western blotting. TRAP-positive osteoclasts were more numerous in the alendronate group at all time points, despite their unactivated phenotype and the presence of apoptotic cells. RANKL expression in the alendronate specimens was inhibited at all time points, unlike in controls. Our findings indicate that the expression of RANKL in the occlusal portion of the bony crypt is unrelated to osteoclast recruitment and differentiation but is crucial to their activation during the creation of the eruption pathway.
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Harre U, Keppeler H, Ipseiz N, Derer A, Poller K, Aigner M, Schett G, Herrmann M, Lauber K. Moonlighting osteoclasts as undertakers of apoptotic cells. Autoimmunity 2012; 45:612-9. [DOI: 10.3109/08916934.2012.719950] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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14
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Jaiprakash A, Prasadam I, Feng JQ, Liu Y, Crawford R, Xiao Y. Phenotypic characterization of osteoarthritic osteocytes from the sclerotic zones: a possible pathological role in subchondral bone sclerosis. Int J Biol Sci 2012; 8:406-17. [PMID: 22419886 PMCID: PMC3303142 DOI: 10.7150/ijbs.4221] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 02/27/2012] [Indexed: 12/21/2022] Open
Abstract
Subchondral bone sclerosis is a well-recognised manifestation of osteoarthritis (OA). The osteocyte cell network is now considered to be central to the regulation of bone homeostasis; however, it is not known whether the integrity of the osteocyte cell network is altered in OA patients. The aim of this study was to investigate OA osteocyte phenotypic changes and its potential role in OA subchondral bone pathogenesis. The morphological and phenotypic changes of osteocytes in OA samples were investigated by micro-CT, SEM, histology, immunohistochemistry, TRAP staining, apoptosis assay and real-time PCR studies. We demonstrated that in OA subchondral bone, the osteocyte morphology was altered showing rough and rounded cell body with fewer and disorganized dendrites compared with the osteocytes in control samples. OA osteocyte also showed dysregulated expression of osteocyte markers, apoptosis, and degradative enzymes, indicating that the phenotypical changes in OA osteocytes were accompanied with OA subchondral bone remodelling (increased osteoblast and osteoclast activity) and increased bone volume with altered mineral content. Significant alteration of osteocytes identified in OA samples indicates a potential regulatory role of osteocytes in subchondral bone remodelling and mineral metabolism during OA pathogenesis.
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Affiliation(s)
- Anjali Jaiprakash
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
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15
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Phosphatidylserine-Containing Liposomes: Potential Pharmacological Interventions Against Inflammatory and Immune Diseases Through the Production of Prostaglandin E2 After Uptake by Myeloid Derived Phagocytes. Arch Immunol Ther Exp (Warsz) 2011; 59:195-201. [DOI: 10.1007/s00005-011-0123-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 11/05/2010] [Indexed: 10/18/2022]
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16
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Crusodé de Souza M, Cruzoé-Souza M, Sasso-Cerri E, Cerri PS. Immunohistochemical detection of estrogen receptor beta in alveolar bone cells of estradiol-treated female rats: possible direct action of estrogen on osteoclast life span. J Anat 2010; 215:673-81. [PMID: 19930518 DOI: 10.1111/j.1469-7580.2009.01158.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The role of estrogen in bone resorption has been specifically related to the effect of estrogen on the signalling pathway that inhibits the formation of osteoclasts. However, osteoclast apoptosis and a significant reduction in the number of these cells have been observed in the alveolar bone of female rats treated with estradiol. In the present study, the expression of estrogen receptor beta (ERbeta) in the cells of alveolar bone was evaluated in estradiol-treated and -untreated female rats. In order to test the possible direct action of estrogen on osteoclasts, the relationship between apoptosis and ERbeta expression in these cells was also analysed. The animals received estradiol for 14 days and the alveolar bone fragments were embedded in paraffin for the quantification of tartrate-resistant acid phosphatase-positive osteoclasts. The expression of ERbeta and apoptosis in the osteoclasts were evaluated by ERbeta immunohistochemistry and Terminal deoxynucleotidyl transferase-mediated dUTP Nick-End Labelling (TUNEL) methods, respectively. To confirm osteoclast death by apoptosis, these cells were analysed under transmission electron microscopy. Some osteoclasts from estradiol-treated animals were found to be undergoing apoptosis and the number of tartrate-resistant acid phosphatase-positive osteoclasts was significantly reduced. ERbeta immunolabelling was observed in the cytoplasm and nuclei of active osteoblasts, osteocytes and osteoclasts in both groups, suggesting a direct participation of estrogen on alveolar bone cells. However, following estradiol treatment, a strong ERbeta immunolabelling was often observed in the TUNEL-positive osteoclasts. Therefore, these results indicate that, in addition to the other signalling pathway, the reduction of alveolar bone resorption is also related to a direct action of estrogen on osteoclasts, promoting apoptosis in these cells, via ERbeta.
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Affiliation(s)
- Mady Crusodé de Souza
- Department of Morphology and Genetics, Federal University of São Paulo, São Paulo, SP, Brazil
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Wu Z, Ma HM, Kukita T, Nakanishi Y, Nakanishi H. Phosphatidylserine-containing liposomes inhibit the differentiation of osteoclasts and trabecular bone loss. THE JOURNAL OF IMMUNOLOGY 2010; 184:3191-201. [PMID: 20176740 DOI: 10.4049/jimmunol.0803609] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Liposomes containing phosphatidylserine (PS) are engulfed by phagocytes including macrophages, microglia, and dendritic cells. PS liposomes (PSLs) mimic the effects of apoptotic cells on these phagocytes to induce the secretion of anti-inflammatory molecules and to inhibit the maturation of dendritic cells. However, the effects of PSLs on osteoclasts, which are also differentiated from the common myeloid precursors, remain to be determined. This study investigated the effects of PSLs on the osteoclastogenesis. In the rat bone marrow culture system, osteoclast precursors phagocytosed PSLs to secrete TGF-beta1 and PGE(2), which in turn inhibited osteoclastogenesis through the downregulation of receptor activator for NF-kappaB ligand, receptor activator of NF-kappaB, ICAM-1, and CD44. Consistent with these in vitro observations, i.m. injection of PSLs significantly increased the plasma level of TGF-beta1 and PGE(2) and decreased the expression of receptor activator for NF-kappaB ligand, receptor activator of NF-kappaB, and ICAM-1 in the skeletal tissues of ankle joints of rats with adjuvant arthritis (AA). A quantitative analysis using microcomputed tomography revealed that PSLs as well as TGF-beta1 together with PGE(2) significantly inhibited AA-induced trabecular bone loss. These observations strongly suggest that PSLs generate TGF-beta1 and PGE(2) release, leading to inhibit osteoclastogenesis and AA-induced trabecular bone loss. Because PS is a component of the cell membrane, PSLs therefore can be a potentially effective pharmacological intervention against abnormal bone loss, such as osteoporosis without deleterious side effects.
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Affiliation(s)
- Zhou Wu
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka, Japan.
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18
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Slaets E, Naert I, Carmeliet G, Duyck J. Early cortical bone healing around loaded titanium implants: a histological study in the rabbit. Clin Oral Implants Res 2009; 20:126-34. [DOI: 10.1111/j.1600-0501.2008.01623.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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19
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Franssen BBGM, van Diest PJ, Schuurman AH, Kon M. Drilling K-wires, what about the osteocytes? An experimental study in rabbits. Arch Orthop Trauma Surg 2008; 128:83-7. [PMID: 17598116 PMCID: PMC2092411 DOI: 10.1007/s00402-007-0382-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Indexed: 11/03/2022]
Abstract
INTRODUCTION The function of osteocytes regarding osteonecrosis has been underestimated for a long time. Recently it has been suggested that apoptosis of osteocytes results in strong osteoclastic bone resorption. Death of osteocytes due to drilling may therefore increase the risk of K-wire loosening. The purposes of our in vivo study were to assess the minimal drill time needed to notice disappearance of osteocytes and to measure the distance of the empty osteocyte lacunae surrounding the drill tract in relation with the insertion time, directly and 4 weeks after drilling Kirschner (K-) wires into the femur and tibia of rabbits. MATERIALS AND METHODS Trocar tipped K-wires (70 mm length and 0.6 mm thickness) were drilled into the femur and tibia of 14 New Zealand white rabbits [mean body weight 2.81 kg (2.66-3.09 kg)]. Six rabbits were terminated following surgery (t = 0) and eight rabbits were terminated 4 weeks (t = 4) after surgery. Following termination, hematoxylin and eosin stained sections were cut from femur and tibia until the drill hole was visible. The sections were evaluated under a light microscope for the presence or absence of osteocytes in osteocyte lacunae surrounding the drill holes. RESULTS All osteocyte lacunae were empty around the K-wires in 50 and 87% of the cases, directly and 4 weeks after the surgery, respectively. The osteocytes disappeared especially beyond a drilling time of 37 s (P = 0.011) and 27 s (P = 0.008) at t = 0 and t = 4, respectively. Furthermore, a significantly positive correlation was seen between the distances of the empty osteocyte lacunae surrounding the drill holes in relation with time at t = 0 (P = 0.008) and t = 4 (P = 0.000). CONCLUSION Although only drilling without cooling was studied, short drilling times may prevent the disappearance of osteocytes in case cooling is not used in clinical practice as is the case in percutaneous K-wire insertion.
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Affiliation(s)
- Bas B G M Franssen
- Department of Plastic, Reconstructive and Hand Surgery, University Medical Center Utrecht, Room G04.122, PO Box 85500, 3508 GA, Utrecht, The Netherlands.
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20
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21
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Faloni APS, Sasso-Cerri E, Katchburian E, Cerri PS. Decrease in the number and apoptosis of alveolar bone osteoclasts in estrogen-treated rats. J Periodontal Res 2007; 42:193-201. [PMID: 17451538 DOI: 10.1111/j.1600-0765.2006.00932.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND AND OBJECTIVE Bone is a mineralized tissue that is under the influence of several systemic, local and environmental factors. Among systemic factors, estrogen is a hormone well known for its inhibitory function on bone resorption. As alveolar bone of young rats undergoes continuous and intense remodeling to accommodate the growing and erupting tooth, it is a suitable in vivo model for using to study the possible action of estrogen on bone. Thus, in an attempt to investigate the possibility that estrogen may induce the death of osteoclasts, we examined the alveolar bone of estrogen-treated rats. MATERIAL AND METHODS Fifteen, 22-d-old female rats were divided into estrogen, sham and control groups. The estrogen group received estrogen and the sham group received corn oil used as the dilution vehicle. After 8 d, fragments containing alveolar bone were removed and processed for light microscopy and transmission electron microscopy. Sections were stained with hematoxylin and eosin and tartrate-resistant acid phosphatase (TRAP)-an osteoclast marker. Quantitative analysis of the number of TRAP-positive osteoclasts per mm of bone surface was carried out. For detecting apoptosis, sections were analyzed by the Terminal deoxynucleotidyl transferase-mediated dUTP Nick-End Labeling (TUNEL) method; TUNEL/TRAP combined methods were also used. RESULTS The number of TRAP-positive osteoclasts per mm of bone surface was significantly reduced in the estrogen group compared with the sham and control groups. TRAP-positive osteoclasts exhibiting TUNEL-positive nuclei were observed only in the estrogen group. In addition, in the estrogen group the ultrastructural images revealed shrunken osteoclasts exhibiting nuclei with conspicuous and tortuous masses of condensed chromatin, typical of apoptosis. CONCLUSION Our results reinforce the idea that estrogen inhibits bone resorption by promoting a reduction in the number of osteoclasts, thus indicating that this reduction may be, at least in part, a consequence of osteoclast apoptosis.
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Affiliation(s)
- A P S Faloni
- Department of Morphology, School of Medicine, Federal University of São Paulo (UNIFESP/EPM), São Paulo, SP, Brazil
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22
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Martin RB. Targeted bone remodeling involves BMU steering as well as activation. Bone 2007; 40:1574-80. [PMID: 17398173 DOI: 10.1016/j.bone.2007.02.023] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Revised: 12/26/2006] [Accepted: 02/22/2007] [Indexed: 01/15/2023]
Abstract
Microdamage removal is an important function of bone remodeling. Experiments have repeatedly shown that remodeling of cortical bone by Basic Multicellular Units (BMUs) is initiated in response to microdamage, and this has become known as "targeted remodeling". This paper considers the possibility that microdamage is not only able to activate new BMUs, but may also attract or "steer" existing BMUs as they continue to tunnel through the bone matrix. An initial analysis of the relationship of between mean microcrack length and BMU resorption space density in cortical bone indicates that BMUs have an effective area about 40 times greater than their actual cross-section. Interpreting this as evidence that the osteoclasts in a tunneling BMU are able to sense and steer toward microdamage, a model is developed for "BMU steering" based on the hypothesis that osteoclasts are guided not only in the principal stress direction, as proposed by Burger et al. (Burger, E.H., Klein-Nulend, J., Smit, T.H. Strain-derived canalicular fluid flow regulates osteoclast activity in a remodelling osteon-a proposal. J. Biomech 36 (2003) 1453-1459), but also toward microdamage, depending on its proximity.
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Affiliation(s)
- R B Martin
- Ellison Musculoskeletal Research Center, U.C. Davis Medical Center, Sacramento, CA 95817, USA.
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Hedgecock NL, Hadi T, Chen AA, Curtiss SB, Martin RB, Hazelwood SJ. Quantitative regional associations between remodeling, modeling, and osteocyte apoptosis and density in rabbit tibial midshafts. Bone 2007; 40:627-37. [PMID: 17157571 DOI: 10.1016/j.bone.2006.10.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Revised: 10/16/2006] [Accepted: 10/17/2006] [Indexed: 11/28/2022]
Abstract
Evidence suggests that osteocyte apoptosis is involved in the adaptive response of bone, although the specific role of osteocytes in the signaling mechanism is unknown. Here, we examined and correlated regional variability in indices of remodeling, modeling, osteocyte apoptosis, and osteocyte density in rabbit tibia midshafts. Histomorphometric analysis indicated that remodeling parameters (BMU activation frequency, osteon density, forming osteon density, and resorption cavity density) were lower in the cranial region compared to other quadrants. In addition, pericortical subregions displayed less remodeling relative to intracortical and endocortical ones. Modeling indices also demonstrated regional variability in that periosteal surfaces exhibited a greater extent of bone forming surface than endosteal ones across all anatomic quadrants. In contrast, endosteal surfaces demonstrated significantly greater surface mineral apposition rates compared to periosteal surfaces in caudal, medial, and lateral but not cranial quadrants. Using TUNEL analysis to detect osteocytes undergoing apoptosis, the density of apoptotic osteocytes was found to be lower in cranial quadrants relative to medial ones. In addition, the densities of osteocyte lacunae, empty lacunae, and total osteocytes were higher in lateral fields relative to caudal quadrants. There was a strong, statistically significant linear correlation between the remodeling indices and apoptotic osteocyte density, supporting the theory that osteocytes undergoing apoptosis produce signals that attract or direct bone remodeling. In contrast, the modeling parameters did not exhibit a correlation with apoptotic osteocytes, although there was a strong correlation between the modeling indices and the density of empty osteocyte lacunae, corroborating previous studies that have found that osteocytes inhibit bone formation. It was found that osteocyte density and osteocyte lacunar density did not significantly correlate with modeling or remodeling parameters, suggesting that cell viability should be examined in studies correlating bone turnover parameters with the functional role of osteocytes in bone adaptation.
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Affiliation(s)
- Nicole L Hedgecock
- Lawrence J Ellison Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of California Davis Medical Center, Sacramento, CA 95817, USA
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Slaets E, Carmeliet G, Naert I, Duyck J. Early Trabecular Bone Healing Around Titanium Implants: A Histologic Study in Rabbits. J Periodontol 2007; 78:510-7. [PMID: 17335375 DOI: 10.1902/jop.2007.060183] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND A detailed insight into the early healing response of trabecular bone to unloaded titanium implants is lacking. METHODS Cylindrical implants were inserted in the tibial epiphysis of rabbits and left to heal for 1 to 42 days. Samples were processed into paraffin or methylmethacrylate sections and histomorphometrically analyzed. RESULTS A hematoma was observed after 1 and 3 days of implant placement. In addition, small fragments of bone trabeculae were detected around the implant as a result of the implant installment procedure. Soon, osteoclasts were observed resorbing these fragments, whereas osteoblasts incorporated them in strands of new bone, thereby making them difficult to distinguish from day 7 onward. At that time, osteoblasts were detected at the edges of the preexisting bone, actively depositing new bone, resulting in maximal osteoid deposition around the implant after 28 days (58%). After 7 days of healing, the presence of basic remodeling units in the surrounding bone was already maximal (P <0.05 versus t = 1 and 3 days). This remodeling activity, together with the new bone formation, provided a firm anchoring of the implant in the trabecular bone. CONCLUSIONS This study evaluated the early cellular events in trabecular bone surrounding titanium implants. The insertion of an implant into bone initiates a series of biologic processes, including the formation of a hematoma, shattered bone fragments adjacent to the implantation site, intensive bone remodeling, and the formation of new bone, eventually leading to the osseointegration of the implant.
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Affiliation(s)
- Elke Slaets
- Department of Prosthetic Dentistry, BIOMAT Research Group, Catholic University Leuven, Leuven, Belgium
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25
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Slaets E, Carmeliet G, Naert I, Duyck J. Early Cellular Responses in Cortical Bone Healing Around Unloaded Titanium Implants: An Animal Study. J Periodontol 2006; 77:1015-24. [PMID: 16734577 DOI: 10.1902/jop.2006.050196] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND A clear understanding of the early cellular events leading to osseointegration of implants is currently lacking. To gain better insight, titanium implants were inserted in a rabbit model and histologic and histomorphometric analyses were performed at early time points after insertion. METHODS Thirty-six cylindrical implants were inserted in the tibial diaphysis of six rabbits and left to heal for 1 to 42 days. Samples were processed into paraffin or methylmethacrylate sections, on which the surface of new bone, region of altered nuclear morphology, relative surface of basic multicellular units (BMUs) and blood vessels, and bone-to-implant contact were measured. RESULTS After coagulum formation, osteoclasts and osteoblasts were observed at the bone surface 1 week after healing. In the preexisting bone, osteocytic lacunae appeared to be devoid of cells. This region of altered nuclear morphology continued to extend for 28 days (P <0.05) after implant insertion. This expansion was accompanied by an invasion of the damaged bone by BMUs that initiated intensive bone remodeling, which reached its maximum after 4 weeks (P <0.05) but was ongoing after 6 weeks of implant insertion. CONCLUSIONS This study evaluated the early cellular events in cortical bone surrounding titanium implants. The insertion of an implant into bone initiates a series of biologic processes, including the formation of a hematoma, altered nuclear morphology of the osteocytes surrounding the implantation site, intensive bone remodeling, and the formation of new bone, eventually leading to the osseointegration of the implant.
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Affiliation(s)
- Elke Slaets
- Department of Prosthetic Dentistry, BIOMAT Research Group, Catholic University Leuven, Leuven, Belgium
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26
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Cerri PS, Katchburian E. Apoptosis in the epithelial cells of the rests of Malassez of the periodontium of rat molars. J Periodontal Res 2005; 40:365-72. [PMID: 16105088 DOI: 10.1111/j.1600-0765.2005.00810.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND OBJECTIVES Epithelial rests of Malassez are clusters of cells derived from Hertwig's root sheath that remain in the periodontal ligament throughout life. Although it is known that the cells of Malassez proliferate, there are no studies showing that they undergo programmed cell death, i.e. apoptosis. In most tissues, proliferation is balanced by apoptosis. Thus we examined regions of the periodontium of young and adult rat molars in the hope of detecting apoptosis. METHODS Wistar rats aged 29, 45 and 120 days were killed with chloral hydrate (600 mg/kg). Fragments containing maxillary molars were removed and fixed in formaldehyde, decalcified, and embedded in paraffin and glycol methacrylate. Sections were stained with hematoxylin/eosin and the Terminal deoxynucleotidyl transferase-mediated dUTP Nick End Labeling (TUNEL) method for detection of apoptosis. Specimens were also fixed in glutaraldehyde-formaldehyde, decalcified and processed for transmission electron microscopy. RESULTS Epithelial rests of Malassez containing round/ovoid basophilic dense bodies and TUNEL-positive structures were found in all specimens examined. Ultrastructural examination revealed that some cells of Malassez contained masses of condensed peripheral chromatin and a shrunken cytoplasm exhibiting intact organelles--images typical of apoptosis. Moreover, round/ovoid electron-opaque structures appeared to be in the process of being engulfed by neighboring epithelial cells of Malassez. CONCLUSIONS Our results demonstrate that epithelial cells of Malassez's rests undergo apoptosis in the developing and adult periodontium. Apoptosis may, together with proliferation, be part of the mechanism of turnover/remodelling of the cells of Malassez.
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Affiliation(s)
- P S Cerri
- Department of Morphology, Dental School, São Paulo State University (UNESP), Araraquara, São Paulo, Brazil.
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Liu ZJ, Anderson MW, Gu GM, King GJ. Apoptosis in the regenerate produced by mandibular osteodistraction in the mature rat*. Orthod Craniofac Res 2005; 8:41-51. [PMID: 15667644 DOI: 10.1111/j.1601-6343.2004.00310.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
UNLABELLED AUTHORS: Liu ZJ, Anderson MW, Gu GM, King GJ. OBJECTIVE Little is known about the contribution of apoptosis to the formation of the regenerate in distraction osteogenesis. This study investigated the role of apoptosis in the regulation of osteogenesis in relation to mandibular distraction rate and recovery time. METHODS One hundred and twenty-nine 3-month rats received unilateral mandibular ramus osteotomy and distraction device placement. After 3-day latency, these were distracted for 5 days. The slow group was distracted a total of 1 mm (0.2 mm/day), the moderate 2 mm (0.4 mm/day), the rapid 3 mm (0.6 mm/day), and the sham was not distracted (0.0 mm/day). Eight to nine rats from each group were killed at 6 (mid-distraction), 10 (early-consolidation), 24 (mid-consolidation) and 38 (late-consolidation) days following device placement. Baseline data were obtained from an additional eight rats killed at day 3 (end of latency). Sagittal sections (7 mum) of the harvested hemi-mandibles were embedded in paraffin, double-stained with the DeadEnd(TM) Colorimetric TUNEL system for apoptotic cells and tartrate-resistant acid phosphatase for osteoclasts. Cell counts of apoptotic cells and osteoclasts (apoptotic or otherwise) were preformed at 40x magnification using a calibrated grid at the middle regions of the caudal, central and rostral parts of the distraction gap. Counting reproducibility was verified as <13%. RESULTS Counts from all three regions were combined because no significant regional difference was found. The majority of the fibrous matrix regenerate was seen at days 6 and 10 while osseous regenerate occurred mainly at days 24 and 38. Significantly higher levels of apoptotic activity were seen at day 24. Apoptotic osteoclasts also peaked at day 24. Apoptotic cell numbers in the slow and moderate groups most closely followed the pattern of the sham in which the apoptosis activity peaked at days 10 or 24. However, those in the rapid group showed delayed peaks at days 24 or 38. CONCLUSIONS Chalmers Street, Surry Hill, NSW 2010, Australia. gshe6437@mail.usyd.edu.au The transition from fibrous to osseous regenerate during mandibular distraction osteogenesis is accompanied by an increase in cell clearance via apoptosis. A slow to moderate distraction rate allows for the most typical pattern of bone healing while a rapid rate prolongs the healing process.
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Affiliation(s)
- Z J Liu
- Department of Orthodontics, Box 357446, University of Washington, Seattle, WA 98195, USA.
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Reaction between Osteoclasts and Osteocytes When They Encounter Each Other at the Bone Resorption Surface during Bone Modeling. J Oral Biosci 2005. [DOI: 10.1016/s1349-0079(05)80026-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Cerri PS. Osteoblasts engulf apoptotic bodies during alveolar bone formation in the rat maxilla. ACTA ACUST UNITED AC 2005; 286:833-40. [PMID: 16047382 DOI: 10.1002/ar.a.20220] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
During bone formation, as in other tissues and organs, intense cellular proliferation and differentiation are usually observed. It has been described that programmed cell death, i.e., apoptosis, takes place in the control of the cellular population by removing of the excessive and damaged cells. Although it is generally accepted that apoptotic bodies are engulfed by professional phagocytes, the neighboring cells can also take part in the removal of apoptotic bodies. In the present study, regions of initial alveolar bone formation of rat molars were examined with the aim to verify whether osteoblasts are capable of engulfing apoptotic bodies, such as professional phagocytes. Rats aged 11-19 days were sacrificed and the maxillary fragments containing the first molar were removed and immersed in the fixative solution. The specimens fixed in glutaraldehyde-formaldehyde were processed for light microscopy and transmission electron microscopy. For the detection of apoptosis, the specimens were fixed in formaldehyde, embedded in paraffin, and submitted to the TUNEL method. The results revealed round/ovoid structures containing dense bodies on the bone surface in close contact to osteoblasts and in conspicuous osteoblast vacuoles. These round/ovoid structures showed also positivity to the TUNEL method, indicating that bone cells on the bone surface are undergoing apoptosis. Ultrathin sections showed images of apoptotic bodies being engulfed by osteoblasts. Occasionally, the osteoblasts exhibited large vacuoles containing blocks of condensed chromatin and remnants of organelles. Thus, these images suggest that osteoblasts are able to engulf and degrade apoptotic bodies.
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Affiliation(s)
- Paulo Sérgio Cerri
- Department of Morphology, Laboratory of Histology and Embryology, Dental School, São Paulo State University, Araraquara, São Paulo, Brazil.
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Nakano Y, Toyosawa S, Takano Y. Eccentric localization of osteocytes expressing enzymatic activities, protein, and mRNA signals for type 5 tartrate-resistant acid phosphatase (TRAP). J Histochem Cytochem 2004; 52:1475-82. [PMID: 15505342 PMCID: PMC3957824 DOI: 10.1369/jhc.4a6378.2004] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Enzymatic activity of type 5 tartrate-resistant acid phosphatase (TRAP) has been regarded as one of the reliable markers for osteoclasts and their precursors. The presence of TRAP activity in osteocytes near the bone resorbing surface has also been pointed out in some reports. However, the significance of TRAP reactions in osteocytes remains controversial and, in fact, there is no agreement as to whether the histochemical enzyme reactions in osteocytes represent the TRAP enzyme generated by the respective osteocytes or is a mere diffusion artifact of the reaction products derived from the nearby osteoclasts. Current histochemical, immunohistochemical, and in situ hybridization studies of rat and canine bones confirmed TRAP enzyme activity, TRAP immunoreactivity, and the expression of Trap mRNA signals in osteocytes located close to the bone-resorbing surface. TRAP/Trap- positive osteocytes thus identified were confined to the areas no further than 200 microm from the bone-resorbing surface and showed apparent upregulation of TRAP/Trap expression toward the active osteoclasts. Spatial and temporal patterns of TRAP/Trap expression in the osteocytes should serve as a valuable parameter for further analyses of biological interactions between the osteocytes and the osteoclasts associated with bone remodeling.
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Affiliation(s)
- Yukiko Nakano
- Biostructural Science, Graduate School of Tokyo Medical and Dental University, Tokyo, Japan
| | - Satoru Toyosawa
- Department of Oral Pathology, Graduate School of Dentistry, Osaka University, Osaka, Japan
| | - Yoshiro Takano
- Biostructural Science, Graduate School of Tokyo Medical and Dental University, Tokyo, Japan
- Correspondence to: Prof. Yoshiro Takano, Biostructural Science, Graduate School of Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan. E-mail:
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Bronckers ALJJ, Sasaguri K, Engelse MA. Transcription and immunolocalization of Runx2/Cbfa1/Pebp2alphaA in developing rodent and human craniofacial tissues: further evidence suggesting osteoclasts phagocytose osteocytes. Microsc Res Tech 2003; 61:540-8. [PMID: 12879421 DOI: 10.1002/jemt.10377] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Runx2/Cbfa1 is a transcription factor, essential for the osteogenic/chondrogenic and odontogenic lineage. Three isoforms of Cbfa1 have been identified, type I (Pebp2alphaA isoform), type II (til-1 isoform), and type III (Osf2 isoform). Here we examined the expression of the Runx2/Cbfa1 during intramembranous and enchondral bone formation in the craniofacial tissues of neonatal rodents (hamster, rat, mouse) and the human fetus. We used a monoclonal antibody raised against the Pebp2alphaA portion and thus potentially recognizing all three isoforms of Runx2/Cbaf1. We report Cbfa1 at the mRNA and protein level in periosteum, preosteoblasts, osteoblasts, young osteocytes, perichondrium, resting and hypertrophic chondrocytes. During active bone remodeling, almost one third of tartrate resistant acid phosphatase (TRAP) positive multinuclear cells identified as osteoclasts were also stained with anti-Pebp2alphaA antibodies. Osteoclasts, however, did not express mRNA transcripts of the Pebp2alphaA gene. Some of the immunopositive structures within these osteoclasts resembled (ingested) cells. TRAP-positive mononuclear cells not attached to bone surfaces did not stain with anti-Pebp2alphaA antibodies. We concluded that the tissue distribution of Runx2/Cbaf1/Pebp2alphaA in ossifying bones of the human fetus is similar to that in neonatal rodent tissues. Osteoclasts do not transcribe the Runx2/Cbfa1 gene but become immunostained by phagocytosing and digesting osteocytes/hypertrophic chondrocytes. The substantial number of osteoclasts involved in phagocytosis of Runx2/Cbfa1 immunopositive cells suggests that phagocytosis is a major way of removing osteocytes/hypertrophic chondrocytes during resorption of bone and cartilage. Finally, the data indicate that positive immunostaining of osteoclasts for typical osteogenic/chondrogenic markers has to be interpreted with caution due to the phagocytosing capacity of these cells.
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Suzuki R, Domon T, Wakita M, Akisaka T. The reaction of osteoclasts when releasing osteocytes from osteocytic lacunae in the bone during bone modeling. Tissue Cell 2003; 35:189-97. [PMID: 12798128 DOI: 10.1016/s0040-8166(03)00020-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Osteocytes are released from the osteocytic lacunae when osteoclasts resorb the bone matrix during bone modeling and remodeling. It remains unknown how osteoclasts react when releasing osteocytes during bone modeling, and the fate of these released osteocytes is also unclear. Femoral mid-shafts of 2-day-old kittens were sectioned into serial 0.5 microm-thick semithin or 0.1 microm-thick ultrathin sections, and examined by light microscopy (LM) and transmission electron microscopy (TEM). The sections showed many osteoclasts at the endosteum but there were no osteoblasts. There were many half-released, fully released, half-exposed, and fully exposed osteocytes on the bone surfaces. Many cell-like structures were seen in the cell bodies of osteoclasts by LM, and some semithin sections were re-sectioned into ultrathin sections for re-observation by TEM. By TEM, these were determinated to be mononuclear cells. The serial ultrathin sections showed that the mononuclear cells appeared to be engulfed in osteoclasts on one section but that the cell was connected with the bone surface of the osteocytic lacuna on another section. These results show that the mononuclear cells in the osteoclasts were osteocytes. The present study suggests that osteoclasts engulf some osteocytes but do not engulf others when releasing osteocytes during bone modeling.
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Affiliation(s)
- R Suzuki
- Department of Oral Anatomy II, Asahi University School of Dentistry, Hozumi 1851, Motosu-gun, Gifu 501-0296, Japan.
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Cerri PS, Boabaid F, Katchburian E. Combined TUNEL and TRAP methods suggest that apoptotic bone cells are inside vacuoles of alveolar bone osteoclasts in young rats. J Periodontal Res 2003; 38:223-6. [PMID: 12608919 DOI: 10.1034/j.1600-0765.2003.02006.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Although it is generally accepted that osteoclasts breakdown and resorb bone matrix, the possibility that they may also be able to engulf apoptotic osteoblasts/lining cells and/or osteocytes remains controversial. Apoptosis of osteoblasts/ lining cells and/or osteocytes and interactions between these cells and osteoclasts are extremely rapid events that are difficult to observe in vivo. A suitable in vivo model for studying these events is the alveolar bone of young rats because it is continuously undergoing intense resorption/remodeling. Thus, sections of aldehyde fixed alveolar bone of young rats were stained by the combined terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method and the tartrate-resistant acid phosphatase (TRAP) method for the simultaneous visualization of apoptotic cells and osteoclasts in the same section. The combined TUNEL and TRAP reactions, in the same section, greatly facilitated visualization of relationship between osteoclasts and apoptotic bone cells during alveolar bone remodeling. Our results showed that several TRAP-positive osteoclasts exhibited large vacuoles containing TUNEL positive apoptotic structures, probably derived from osteoblasts/lining cells and/or osteocytes. These results support the idea that alveolar bone osteoclasts are able to internalize dying apoptotic bone cells.
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Affiliation(s)
- P S Cerri
- Department of Morphology, São Paulo State University (UNESP-Araraquara) SP, Brazil
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