[Bone morphogenetic protein-2, -4, -6, -7 and -9 differentially mediated osteogenic differentiation of immortalized...

This study was aimed to investigate the mesenchymal stem cell (MSC) phenotypes of immortalized odontoblasts(iODs) and bone morphogenetic protein -2, -4, -6, -7, and -9 (BMPs) differentially regulate the mineralization of iODs.

ODs were immortalized by SV40 T antigen to establish iOD lineages, and the endogenous expression of BMPs was successively examined. Recombinant adenoviruses expressing BMPs and GFP were generated using Ad-Easy technology. The proliferation capability of iODs was examined using an MTT kit. MSC markers of iODs were examined by immunofluorescence. In vitro, semiquantitative RT-PCR, alkaline phosphatase(ALP) activity assay, matrix mineralization assay and oil red O staining assay were used to examine the osteogenic and adipogenic differentiation capabilities of iODs. Statistical significance among groups was analyzed by one-way analysis of variance and Scheffe's multiple comparison test was SPSS 21.0 software package. Finally, the volume and density of ectopic mineralized tissues formed in vivo were assessed by micro-CT and histological analysis.

ODs can be efficiently immortalized by SV40 T antigen, and the resulting iODs maintained an excellent proliferative activity, expressed certain MSC markers and possessed multiple differentiation capabilities. BMP-2 and BMP-9 regulated iODs osteogenic differentiation better than BMP-4, -6, and -7.

Our findings suggest that ODs and osteogenic growth factors such as BMP-2 and BMP-9 can be used as an efficacious strategy for bone tissue engineering.