2005 Fiscal Year Final Research Report Summary
Study of the life span and cell death of osteoclasts with cell fusion of green mouse
| Project/Area Number |
16591819
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Morphological basic dentistry
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| Research Institution | Hokkaido University |
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Principal Investigator |
DOMON Takanori Hokkaido University, Graduate School of Dental Medicine, associate professor, 大学院・歯学研究科, 助教授 (50217618)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Tsuneyuki Hokkaido University, Gradate School of Dental Medicine, associate professor, 大学院・歯学研究科, 助教授 (80200822)
TAKAHASHI Shigeru Hokkaido University, Graduate School of Dental Medicine, instructor, 大学院・歯学研究科, 助手 (70241338)
MITOME Masato Hokkaido University, Hokkaido University Hospital, lecturer, 講師 (50261318)
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| Project Period (FY) |
2004 – 2005
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| Keywords | osteoclasts / odontoclasts / multinucleation / cell fusion / cell death / apoptosis / necrosis |
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| Research Abstract |
Life span and cell death of multinucleated osteoclasts and odontoclasts remain unclear. The present study examines survival of osteoclasts after cell fusion and aims to clarify the cell death of these multinucleated cells.
According to the schedule of the research on 2004, the following results are shown : in culture, osteoclasts are formed from mouse bone marrow cells in the presence of M-CSF and RANKL. When stopping the addition of M-CSF and RANKL to cell culture, there are few cell fusion between osteoclasts and cells gradually degenerate. When adding bone marrow cells of green mouse, M-CSF, and RANKL to culture dish, cell fusion between osteoclasts and mononuclear cells with green nuclei occurs. After fixation, a mix of normal nuclei and green nuclei in an osteoclast was observed by fluorescent microscopy, and most cell without green nuclei were dying.
According to the schedule of the research on 2005, the following results are shown : to know cell death of odontoclasts in normal condition, human deciduous teeth were used in this study. For immunohistochemistry (IHC), TUNEL and TRAP activities were detected on paraffin section. For transmission electron microscope (TEM), 0.5μm-thick serial semithin sections were made, and ultrastructures of apoptotic odontoclasts were examined. By IHC, nuclei of TRAP-positive odontoclasts did not show TUNEL reaction, however there were TRAP-positive structures with TUNEL-positive nuclei. By TEM, characteristic nuclear fragments were seen in odontoclasts, and there were typically electron dense condensed mitochondria in the cytoplasm. There were odontoclasts with swelling of cytoplasm and cytoplasmic compartments ; mitochondria and rough-surfaced endoplasmic reticulum. These IHC and TEM results show that cell death of odontoclasts under physiological root resorption of human deciduous teeth reveals two patterns of apoptosis and necrosis.
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