Dental Epithelial Histomorphogenesis in vitro

Abstract

Recent developments in tooth-tissue engineering require that we understand the regulatory processes to be preserved to achieve histomorphogenesis and cell differentiation, especially for enamel tissue engineering. Using mouse first lower molars, our objectives were: (1) to determine whether the cap-stage dental mesenchyme can control dental epithelial histogenesis, (2) to test the role of the primary enamel knot (PEK) in specifying the potentialities of the dental mesenchyme, and (3) to evaluate the importance of positional information in epithelial cells. After tissue dissociation, the dental epithelium was further dissociated into individual cells, re-associated with dental mesenchyme, and cultured. Epithelial cells showed a high plasticity: Despite a complete loss of positional information, they rapidly underwent typical dental epithelial histogenesis. This was stimulated by the mesenchyme. Experiments performed at E13 demonstrated that the initial potentialities of the mesenchyme are not specified by the PEK. Positional information of dental epithelial cells does not require the memorization of their history.

Tooth Organ Engineering: Biological Constraints Specifying Experimental Approaches

“…A complete epithelial histogenesis could be achieved within 4 to 6 days, including the inner and outer dental epitheliums, the stellate reticulum and, later, the stratum intermedium ( Fig. 2A, C ;Hu et al, 2005). This stratum intermedium plays an essential role in the functional differentiation of ameloblasts (Lesot & Brook, 2009;Nait Lechguer et al, 2011;Yoshida et al, 2010).…”

“…The next challenge will be to deal with the engineering of larger teeth, where full vascularization and innervation will become critical. As far as possible, it may be better to work in the absence of scaffold or matrices to engineer whole teeth (Hu et al, 2005(Hu et al, , 2006aOhazama et al, 2004). It better fits with the necessity to preserve epithelial-mesenchymal interactions and with the maintenance of gradual cell differentiation.…”

Tissue Engineering for Tissue and Organ Regeneration

“…Using embryonic dental cells, the PEK reproducibly formed during early stages of the re-association in vitro (Fig. 2C) and was characterized by the condensation of non dividing cells in the epithelium, their expression of Shh and a local concentration of apoptosis (Hu et al, 2005). Four days after this PEK specification, cusps developed, showing that this structure was functional ( Fig.…”

“…Embryonic dental cells are commonly used as they allow a full tooth development from cellcell re-associations Hu et al, 2005;Nakao et al, 2007). A two stages methodology has been developed, where cell-cell re-associations are cultured in vitro before implantation in adult mice ( Fig.…”

“…As far as possible, it may be better to work in the absence of scaffold or matrices to engineer whole teeth (Hu et al, 2005(Hu et al, , 2006aOhazama et al, 2004). It better fits with the necessity to preserve epithelial-mesenchymal interactions and with the maintenance of gradual cell differentiation.…”