engleski

Morphogenetic activity of silica and bio-silica on the expression of genes controlling biomineralization of tooth enamel using SaOS-2 cells

In a previous study (Schröder et al. 2005 [J. Biomed. Mat. Res. Part B - Applied Biomaterials 75B: 387-392]) we demonstrated that SaOS-2 human osteogenic sarcoma cells, cultivated on bio-silica matrices, respond with an increased hydroxyapatite deposition. In the present contribution we investigate, if silicabased components (Na-silicate, TEOS [tetraethyl orthosilicate], silicananoparticles) (i) change the extent of biomineralization in vitro (SaOS-2 cells) and (ii) cause an alteration of the expression of the genes amelogenin, ameloblastin and enamelin, which are characteristic for ameloblasts. At first we demonstrate that the viability of SaOS-2 cells is not affected by the silica-based components. If Na-silicate or TEOS is added together with ß-glycerophosphate, an organic phosphate donor, a significant increase of biomineralization is measured. Finally, the expression levels of the amelogenin, ameloblastin and enamelin genes were determined in SaOS-2 cells during exposure to the silica-based components. After exposure for 2 days the expression levels of amelogenin and enamelin strongly increased in response to the silica-based components, while no significant change was seen for ameloblastin. We conclude that the levels of the structural molecules of the enamel matrix, amelogenin and enamelin, increase in the presence of silicabased components and substantially contribute to the extent of hydroxyapatite crystallite formation. These results demonstrate that silica-based components augment the hydroxyapatite deposition in vitro, and suggest that enzymatically synthesized bio-silica (via silicatein) might be a promising route for tooth reconstruction in vivo.

Enamel; Amelogenin; Ameloblastin; Enamelin; Silicate; Tooth reconstitution

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