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Experimental Induction of Odontoblast Differentiation and Stimulation During Preparative Processes Cells and Materials Volume 3 Number 2 Article 8 1993 Experimental Induction of Odontoblast Differentiation and Stimulation During Preparative Processes H. Lesot Institut de Biologie Médicale C. Begue-Kirn Institut de Biologie Médicale M. D. Kubler Institut de Biologie Médicale J. M. Meyer Institut de Biologie Médicale A. J. Smith Dental School, Birmingham See next page for additional authors Follow this and additional works at: https://digitalcommons.usu.edu/cellsandmaterials Part of the Biomedical Engineering and Bioengineering Commons Recommended Citation Lesot, H.; Begue-Kirn, C.; Kubler, M. D.; Meyer, J. M.; Smith, A. J.; Cassidy, N.; and Ruch, J. V. (1993) "Experimental Induction of Odontoblast Differentiation and Stimulation During Preparative Processes," Cells and Materials: Vol. 3 : No. 2 , Article 8. Available at: https://digitalcommons.usu.edu/cellsandmaterials/vol3/iss2/8 This Article is brought to you for free and open access by the Western Dairy Center at DigitalCommons@USU. It has been accepted for inclusion in Cells and Materials by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. Experimental Induction of Odontoblast Differentiation and Stimulation During Preparative Processes Authors H. Lesot, C. Begue-Kirn, M. D. Kubler, J. M. Meyer, A. J. Smith, N. Cassidy, and J. V. Ruch This article is available in Cells and Materials: https://digitalcommons.usu.edu/cellsandmaterials/vol3/iss2/8 Cells and Materials, Vol. 3, No. 2, 1993 (Pages201-217) 1051-6794/93$5. 00 +. 00 Scanning Microscopy International, Chicago (AMF O'Hare), IL 60666 USA EXPERIMENTAL INDUCTION OF ODONTOBLAST DIFFERENTIATION AND STIMULATION DURING REPARATIVE PROCESSES 1 1 1 2 2 1 H. Lesot *, C. Begue-Kirn 1, M.D. Kubler , J.M. Meyer , A.J. Smith , N. Cassidy , and J.V. Ruch 1Institut de Biologie Medicale, Faculte de Medecine, Strasbourg, France 2Department of Oral Pathology, Dental School, Birmingham, United Kingdom (Received for publication March 24, 1993 , and in revised form May 8, 1993) Abstract Introduction In vivo implantation experiments have shown that Tooth germs consist of two interacting tissues, the ethylenediaminetetraaceticacid(EDTA)-solublefractions enamel organ and the dental papilla, with an interposed of dentin stimulate reparative dentinogenesis. When iso­ basement membrane. During tooth development, only lated embryonic dental papillae were cultured in the the ecto-mesenchymal cells in contact with the basement presence of these dentin constituents, odontoblast membrane give rise to odontoblasts (Ruch et al., 1982). cytological and functional differentiation could be ini­ However, all dental mesenchymal cells which derive tiated and maintained in the absence of an enamel organ. from neural crest cells (Chibon, 1966, 1967; Lumsden, These effects were attributed to the presence of TGF-/1- 1987; Smith and Hall, 1990) might be potential odonto­ related molecules [TGF-/11 or bone morphogenetic pro­ blasts. This potentiality is probably expressed in repa­ tein-2a (BMP-2a)] which had to be used in combination rative processes where dental mesenchymal cells can with an EDT A-soluble fraction of dentin in order to spe­ give rise to a second generation of odontoblasts cifically affect competent preodontoblasts. These (Schroder, 1985; Yamamura, 1985). The purpose of this EDT A-soluble constituents present in dentin could be re­ review is to compare control mechanisms involved in the placed by heparin or fibronectin which both have been two processes of odontoblast differentiation and to see reported to interact with TGF-/1. The association of whether they may share some analogous steps. such defined matrix components with a TGF-/1-related molecule represents a biologically active complex trig­ Odontoblast Differentiation During Odontogenesis gering odontoblast functional differentiation. In response to caries, odontoblasts modulate their Phenotypic aspects of odontoblasts differentiation secretory activity and are stimulated to elaborate reac­ tionary dentin. This might be induced by active molec­ The combination of specific morphological, cyto­ ules such as IGF, TGF-6 or BMP which are liberated logical and functional features determines the identity of from dentin consecutively to the demineralization odontoblasts (Ruch, 1985). Odontoblast terminal differ­ process. entiation is characterized by a sequence of cytological Reparative dentinogenesis is distinct from reac­ and functional changes. First, preodontoblasts become tionary dentinogenesis and more complex since it impli­ postmitotic and during the last cell division, the mitotic cates the differentiation of precursor cells present in the spindle lies perpendicular to the basement membrane dental papilla. The developmental history of these cells (Osman and Ruch, 1976; Ruch, unpublished observa­ is different from that of the physiological predontoblasts tions). Only the daughter cells in contact with the base­ in developing teeth. The nature of these "stem cells" ment membrane will become an odontoblast. These cells and the mechanism of their induction still remain open will then concomitantly elongate and polarize; these two questions. events cannot be separated experimentally. It is the process of elongation and polarization that distinguishes Key Words: Odontoblast differentiation , polarization, a preodontoblast from an odontoblast. As such , these dentin, transforming growth factor beta, fibronectin , two characteristics provide us with the first markers of extracellular matrix, cell-matrix interaction. odontoblast differentiation and will be accompanied by •Address for correspondence: the functional activities of the cell. H. Lesot, Polarization itself includes cytological and func­ Institut de Biologie Medicale, Faculte de Medecine, tional aspects. The cytological changes, which are real­ 11 rue Humann, 67085 Strasbourg Cedex, France ized in a few hours in the mouse embryo (Olive and Telephone number: 33 (88) .35.87.61 Ruch, 1982b), have been described for many years and FAX Number: 33 (88) 25 . 78 . 17 or 33 (88). 24 . 20.05 include the position of the nucleus at the basal pole of 201 H. Lesot et al. the differentiated cell, the development of the ergasto­ Ruch et al., 1982; Slavkin, 1978; Thesleff and plasmic cisternae which align parallel to the long axis of Hurmerinta, 1981; Thesleff et al., 1989). The terminal the odontoblast, changes in the distribution of the organ­ differentiation of odontoblasts requires the presence of elles, the development of junctional complexes, and the a stage specific basement membrane (Kollar, 1983; formation of a cell process (Garant and Cho, 1985; Lumsden, 1987; Meyer et al., 1977; Osman and Ruch, Takuma and Nagai, 1971). Cytoskeletal elements are in­ 1981; Ruch et al. , 1982, 1983; Slavkin, 1990; Slavkin volved in these changes; the use of either cytochalasin B et al., 1988). This basement membrane might act either or colchicin blocks the cytological and functional differ­ as a specific substrate (Lesot et al. , 1981, 1985b, 1992; entiation of odontoblasts (Ruch et al. , 1975). Microtu­ Mark et al., 1990) or as a reservoir of paracrine and bules (Nishikawa and Kitamura, 1987), intermediate fila­ autocrine factors (Cam et al., 1992; Ruoslahti and ments (Fausser et al., 1990; Lesot et al., 1982) and mi­ Yamaguchi, 1991; Schubert, 1992). The dental base­ crofilaments (Kubler et al., 1988; Lesot et al., 1982; ment membrane might thus participate in the control of Nishikawa and Kitamura, 1986; Ruch et al., 1987) are both cell proliferation kinetics (Olive and Ruch, 1982a) reorganized during odontoblast elongation and polariza­ and cytodifferentiation. tion . Odontoblast polarization has been suggested to re­ Among the constituents of the basement mem­ sult from the existence of a surface to which pulp cells brane, fibronectin was shown to be redistributed during might attach (Veis, 1985a). A polarity may already ex­ odontoblast polarization (Lesot et al., 1981; Thesleff ist before the cell elongates. For example, the basement and Hurmerinta, 1981) and thus was suspected to play a membrane induces a polarity in the preodontoblast which role in the control of odontoblast differentiation. Sever­ results in the specific orientation of the mitotic spindle al reports have shown that this molecule could interact during the last cell division (Osman and Ruch, 1976; with cell surfaces for example by means of integrins Ruch , unpublished observations). (Hynes, 1992) and that the /31 subunit of integrins could The functional aspects of odontoblast differentia­ interact with the microfilament system by means of ei­ tion have also been extensively studied in several labora­ ther talin (Horwitz et al., 1986) or, more probably, tories (Butler et al. , 1992; Linde, 1989; Veis, 1985b) a -actinin (Otey et al. , 1990). Fibronectin was found to and have demonstrated qualitative and quantitative meta­ interact with dental mesenchymal cell surfaces by means bolic changes leading to the polarized secretion of pre­ of three high molecular weight membrane proteins dentin-dentin which accumulates at the apical pole of (Lesot et al., 1985a). At least one of these proteins, odontoblasts, at the epithelio-mesenchymal junction. with a molecular weight of 165 kDa, is expressed by Functional odontoblasts synthesize collagens type I, type odontoblasts and was found to play a role in the I trimer (Lesot, 1981; Lesot and Ruch, 1979; reorganization of microfilaments during odontoblast Munksgaard et al. , 1978; Wohllebe
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