Acceleration effect of human recombinant bone morphogenetic protein-2 on differentiation of human pulp cells into odontoblasts

Predictable pulp capping procedures remain problematic, possibly because of the lack of appropriate stimulating factors for dentin formation. The present study examines the ability of one such stimulating factor, bone morphogenetic protein-2, to accelerate the differentiation of human dental pulp cells into odontoblasts. The number and morphology of cells between groups treated with 0 and 100 ng/ml of human recombinant bone morphogenetic protein-2 (rhBMP-2) did not significantly differ. However, ALPase activity (a marker for biomineralization) in the group stimulated with rhBMP-2 was more than double that of the control group. We then measured the expression of mRNA encoding dentin sialophosphoprotein (DSPP) as a marker of odontoblasts in rhBMP-2-stimulated human pulp cells using a quantitative polymerase chain reaction. The expression of DSPP mRNA in cells stimulated for 24 h by 1000 ng/ml of rhBMP-2 was approximately 20-fold and 5-fold higher than that by stimulated by 10 and 100 ng/ml, respectively. These findings show that rhBMP-2 promoted the differentiation of human dental pulp cells into odontoblasts but did not affect cell proliferation, suggesting that rhBMP-2 may have therapeutic utility in vital pulp therapy.