Objective      To determine osteogenic differentiation effects of bone morphogenetic proteins (BMP 2

7 and 9) on human periodontal ligament stem cells (hPDLSCs)

and determine the effect of BMPs-extracellular signal-regulated kinase 5 (ERK5) signaling pathway on osteogenic differentiation.       Methods      hPDLSCs were isolated from fresh periapical tissues and cultured by tissue block and enzyme digestion

and then identified. After hPDLSCs were infected by adenovirus vectors carrying GFP

BMP2

BMP7 and BMP9 respectively (Ad-GFP

Ad-BMP2

Ad-BMP7 and Ad-BMP9)

the activity and quantity of alkaline phosphatase were determined for early osteogenic differentiation

and calcium nodule deposition was studied by alizarin red staining for late osteogenic differentiation. And the expression levels of some genes related to osteogenic differentiation and osteopontin were detected by qRT-PCR. After BMP9 was determined as exerting strongest effect on osteogenic differentiation

the phosphorylation of ERK5 was detected after hPDLSCs were intervened with Ad-BMP9 and BIX02189 (inhibitor of ERK5 signaling pathway) for 24 h respectively for the effect of the signaling pathway on osteogenic differentiation.       Results      The isolated and cultured hPDLSCs were fibroblast-likes

in swirl-like arrangement

positive to vimentin while negative to keratin

and showing mesenchymal properties and clone forming ability. Adenovirus vectors Ad-BMP2

BMP7 and BMP9 all had inducing effects on osteogenic differentiation in hPDLSCs

and enhanced the activity of alkaline phosphatase and the mRNA expression of relative genes than Ad-GFP vector (P0.05)

what’s more

adenovirus vector BMP9 had strongest effects. Western blotting showed that BMP9 up-regulated the phosphorylation of ERK5

and BIXO2189 decreased the phosphorylation of ERK5 in a dose-dependent manner. And BIX02189 attenuated BMP9-induced osteogenic differentiation of hPDLSCs. The activity of alkaline phosphatase and mRNA expression levels of relative genes were significantly lower in the BIX02189 groups than the BMP9 group (P0.05).       Conclusion      BMP9 has strong the osteogenesis induction effect on hPDLSCs. ERK5 signaling pathway exerts a positive regulatory effect on BMP9-induced osteogenic differentiation.