Role of Hertwig's epithelial root sheath cells in tooth root development

Authors

  • Margarita Zeichner-David,

    Corresponding author
    1. Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, Los Angeles, California
    • Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, 2250 Alcazar Street, CSA 106, Los Angeles, CA 90033
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  • Keiji Oishi,

    1. Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, Los Angeles, California
    2. Tokushima University, Department of Periodontology and Endodontics, Tokushima, Japan
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  • Zhengyan Su,

    1. Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, Los Angeles, California
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  • Vassili Zakartchenko,

    1. Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, Los Angeles, California
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  • Li-Sha Chen,

    1. Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, Los Angeles, California
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  • Higinio Arzate,

    1. Universidad Nacional Autónoma de México, Facultad de Odontología, México DF, Mexico
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  • Pablo Bringas Jr.

    1. Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, Los Angeles, California
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Abstract

During tooth development, after the completion of crown formation, the apical mesenchyme forms the developing periodontium while the inner and outer enamel epithelia fuse below the level of the crown cervical margin to produce a bilayered epithelial sheath termed Hertwig's epithelial root sheath (HERS). The role of HERS cells in root formation is widely accepted; however, the precise function of these cells remains controversial. Functions suggested have ranged from structural (subdivide the dental ectomesenchymal tissues into dental papilla and dental follicle), regulators of timing of root development, inducers of mesenchymal cell differentiation into odontoblasts and cementoblasts, to cementoblast cell precursors. The characterization of the HERS phenotype has been hindered by the small amount of tissue present at a given time during root formation. In this study, we report the establishment of an immortal HERS-derived cell line that can be maintained in culture and then induced to differentiate in vitro. Characterization of the HERS phenotype using reverse transcriptase-polymerase chain reaction and Western blot immunostaining suggests that HERS cells initially synthesize and secrete some enamel-related proteins such as ameloblastin, and then these cells appear to change their morphology and produce a mineralized extracellular matrix resembling acellular cementum. These studies suggest that the acellular and cellular cementum are synthesized by two different types of cells, the first one by HERS-derived cementoblasts and the later by neural crest-derived cementoblasts. Developmental Dynamics 228:651–663, 2003. © 2003 Wiley-Liss, Inc.

Ancillary