Objectives: To study the induction of the biomineralization process in fibroblast and osteoblast mammalian cells by overexpressing PP. This will provide a model system to study the initiation of the mineralization process. In addition, this study will form the basis for studying the interaction of ECM proteins with novel forms of inorganic materials containing Ca2+ and PO43- species exhibiting various morphologies.
Methods: Establish stably transfected cell NIH-3T3 and MC3T3 cell lines with exon 5 of DSPP (Phosphophoryn) and assess the effect of PP on the type of mineral formation in the mineralizing vs non-mineralizing cell lines. Moreover, we will assess the PP effect on the regulation of other bone/dentin gene expression.
Results: Alizarin red and von kossa positive staining following the overexpression of PP in NIH3T3 cells indicated the presence of mineral deposits. Results of the characterization of the minerals to date indicates that the mineralized phase could correspond to an amorphous phosphate, carbonate or mixed carbonate apatite phases, brushite and hydroxyapatite depending on the crystallization kinetics. We will also discuss our novel approach to study the process of biomineralization and how recombinant PP interact with a novel nanostructured calcium phosphate aquagel matrix synthesized with controlled variation of calcium and phosphate compositions.
Conclusions: The data appears to indicate that the cells interact with the PP/mineral complex and provide the desired stability. The exact role of the cells' interaction with the PP/mineral complex is not fully understood and it is currently one of our research foci of this interesting phenomena.