The localization of epithelial root sheath cells during cementum formation in rat molars

Alatlı, İdil; Lundmark, Carin; Hammarström, Lars

doi:10.1111/j.1600-0765.1996.tb00512.x

Cited by 22 publications

(23 citation statements)

References 27 publications

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“…In conclusion, our results are supported by a study by Alatli et al (1996), who reported that the development of cellular cementum seems to be induced when cells of the dental sac attach to the inner enamel epithelium of the HERS. Our results suggested that inner enamel epithelial cells most probably play an important role by differentiating into cementoblast when they contact mesenchymal cells of the dental sac by desmosomelike structures, and epithelial-mesenchymal interactions occur.…”

Section: Discussionsupporting

confidence: 90%

Behavior of epithelial root sheath during tooth root formation in porcine molars: TUNEL, TEM, and immunohistochemical studies

Suzuki

Inoue

Shimono

et al. 2002

Anatomy and Embryology

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The behavior of epithelial cells during tooth root formation in porcine molars was investigated using TUNEL, immunohistochemical and transmission electron microscopic methods. Cells of Hertwig's epithelial root sheath (HERS) expressed bcl-2, but were TUNEL-negative. Epithelial cells of HERS were tightly connected and surrounded by a continuous basement membrane. When dental papilla cells were attached to the inner HERS, they became positive for osteopontin (OPN). The inner basement membrane was intermittent immediately after those cells started to synthesize dentin matrix, and the intercellular spaces of the HERS became wider. Dental sac cells then migrated between the fragmented HERS and were directly connected to epithelial cells by desmosome-like structures. After the cementum was synthesized by these mesenchymal cells, epithelial cells aggregated to form cell clusters, which were again surrounded by a continuous basement membrane. These results suggest that fragmentation of the HERS is due to the invasion of dental sac cells, but is not related to cell death. Furthermore, the differentiation of dental papilla cells into odontoblasts occurred following their connection to the HERS through the basement membrane. Moreover, it is suggested that the differentiation of dental sac cells into cementoblasts occurred upon their direct connection to epithelial cells of the HERS.

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Section: Discussionsupporting

confidence: 90%

Behavior of epithelial root sheath during tooth root formation in porcine molars: TUNEL, TEM, and immunohistochemical studies

Suzuki

Inoue

Shimono

et al. 2002

Anatomy and Embryology

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“…The expression of keratin by HERS in vivo has been demonstrated by several investigators (Alatli et al, 1996;Kaneko et al, 1999;Onishi et al, 1999), and as expected, HERS in vitro express keratin. Unexpected was the simultaneous expression of vimentin mRNA, although coexpression of vimentin and keratin has been reported for other epithelial cell lines maintained in culture (Zuk et al, 1989).…”

Section: Do Hers Undergo Emt?supporting

confidence: 76%

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

Zeichner‐David

Oishi

et al. 2003

Developmental Dynamics

204

176

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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.

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“…26 Amelogenins are primarily expressed by ameloblasts during formation of the enamel matrix of the dental crown; however, amelogenin-related proteins have also been shown to be expressed later in odontogenesis by the inner cell layer of HERS immediately prior to acellular cementum formation. 4,5 In both animal and clinical studies, the application of EMD has been shown to stimulate periodontal connective tissue attachment formation 12-14 perhaps through the reintroduction during periodontal wound healing of epithelial mesenchymal interactions that were active during development of the periodontal connective tissue attachment. 15 However, the precise mechanism of EMD stimulation of periodontal connective tissue attachment regeneration is at present unknown.…”

Section: Discussionmentioning

confidence: 98%

“…In turn, mineralization of the newly secreted dentin extracellular matrix induces the inner cell layer of HERS to synthesize and secrete an extracellular matrix on the newly formed dentin surface. 5 Proteins present in the HERS secreted matrix include proteins related to the enamel protein extracellular matrix, specifically amelogenin-related proteins. 4 After extracellular matrix secretion by HERS, the epithelial cells lose contact with the root surface and HERS dissipates; however, epithelial remnants persist in the mature periodontal ligament as cell rests of Malessez.…”

Section: Introductionmentioning

confidence: 99%

Effect of enamel matrix proteins on the phenotype expression of periodontal ligament cells cultured on dental materials

Inoue

LeGeros

Hoffman

et al. 2004

J Biomedical Materials Res

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Cells within the periodontal ligament have the potential to regenerate a periodontal connective tissue attachment on pathologically exposed root surfaces as well as on several material surfaces including titanium. However, rather than a periodontal connective tissue attachment, a fibrous encapsulation or chronic inflammatory response has been reported at the material connective tissue interface for most dental materials. Cementum is the first tissue of the periodontal connective tissue attachment to develop and the secretion of enamel matrix related proteins on the newly mineralized dentin surface precedes and is thought to induce cementum formation. Enamel matrix-related proteins may also function in the adult because the application of an acid extract of porcine enamel protein matrix (Emdogain(R), EMD) on pathologically exposed root surfaces has been shown to result in cementum regeneration. Therefore, the objective of the present study was to determine whether the application of EMD to materials that do not normally support cementogenesis in vivo would alter the in vitro phenotype of periodontal ligament (PDL) cells including the synthesis of cementum-associated extracellular matrix proteins. Primary PDL cells were established from 21-day-old Sprague-Dawley rats, and were cultured on four materials commonly encountered in dental practice (gutta percha, calcium hydroxide, amalgam, and super EBA cement) with and without the application of EMD. After 7 or 14 days of culture, total-DNA content, collagen synthesis, alkaline phosphatase activity, and the synthesis of a 42-kDa cementum-associated extracellular matrix protein were determined. PDL cells cultured on all materials had decreased total DNA content. The application of EMD further decreased total DNA content. PDL cells cultured on gutta percha and calcium hydroxide with the application of EMD had similar levels of collagen synthesis and alkaline phosphatase activity but also expressed a 42-kDa cementum extracellular matrix-associated protein when compared to the other groups. These results suggest that EMD can alter the phenotype of PDL cells when cultured on these dental materials.

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The localization of epithelial root sheath cells during cementum formation in rat molars

Cited by 22 publications

References 27 publications

Behavior of epithelial root sheath during tooth root formation in porcine molars: TUNEL, TEM, and immunohistochemical studies

Behavior of epithelial root sheath during tooth root formation in porcine molars: TUNEL, TEM, and immunohistochemical studies

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

Effect of enamel matrix proteins on the phenotype expression of periodontal ligament cells cultured on dental materials

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