2006 Fiscal Year Final Research Report Summary
Signalings and molecular regulation of root formation and eruption of mouse incisor and molars
| Project/Area Number |
17591929
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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 | The Nippon Dental University |
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Principal Investigator |
SATO Kaori The Nippon Dental University, School of Life Dentistry at Tokyo, Lecturer, 生命歯学部, 講師 (90287772)
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| Co-Investigator(Kenkyū-buntansha) |
TAYA Yuji The Nippon Dental University, School of Life Dentistry at Tokyo, Associate Professor, 生命歯学部, 助教授 (30197587)
SHIMAZU Yoshihito The Nippon Dental University, School of Life Dentistry at Tokyo, Lecturer, 生命歯学部, 講師 (10297947)
KANRI Yoriaki The Nippon Dental University, School of Life Dentistry at Tokyo, Assistant Professor, 生命歯学部, 助手 (40366761)
AOBA Takaaki The Nippon Dental University, School of Life Dentistry at Tokyo, Professor, 生命歯学部, 教授 (30028807)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Odontology / Pathology / Development / Tooth germ / Root formation / Eruption / Hertwig's epithelial root sheath / 3D-reconstruction |
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| Research Abstract |
Most promising approaches toward dental tissue regeneration include replication of normal developmental conditions and design of appropriate combinations of cells, molecular factors, and scaffolds to promote tissue regrowth. Development of Hertwig's epithelial root sheath (HERS) and cementogenesis are crucial steps in root formation and eruption. Thus we performed a systematic study of the development of HERS cells throughout mouse molar root formation. This disproportionate growth rate between HERS and root likely explains the fenestration of HERS. Immunohistochemistry showed that HERS may stimulate odontoblast differentiation through FGF secretion and that proliferation and architecture of HERS are under regulation of several growth factors, e/g., EGF, IGF and serotonin. Cell proliferation assays revealed that HERS cells during initial root formation exhibit significant proliferation activities, whereas HERS proliferation rates do not match the proliferation rates of connective tissue cells contributing to root growth. In order to follow the fate and distribution of HERS cells along the developing root surface, we marked epithelial cells with ant-keratin antibodies and then conducted 3D reconstructions of anti-keratin labeled serial sections of postnatal developing mouse first mandibular molars. 3D observations and histomorphometric analysis supported four possible fates of HERS cells: apoptosis, incorporation into the advancing cellular cementum front, migration away from the root surface into the periodontal ligament, and epithelial-mesenchymal transformation. Regarding the migratory capacity of HERS cells, it was validated that a few HERS cells migrate away from the root surface to form the rests of Malassez, which play significant roles in the regulation and maintenance of the periodontal ligament space.
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