Abstract: PURPOSE: To determine the effect of p38 MAPK signaling pathway on BMP9-induced osteogenetic differentiation of human periodontal ligament stem cells( hPDLSCs). METHODS: hPDLSCs were collected in vitro, and adenovirus vectors were used to infect hPDLSCs; then the activity and staining of alkaline phosphatase(ALP) were detected ,the expression of osteopontin (OPN) and osteocalcin(OCN) were detected by qPCR ,and the calcium nodule deposition was used to analyse the ability of BMP9-induced hPDLSCs osteogenetic differentiation. Phosphorylation of p38 and MKK3/6 was detected after hPDLSCs was intervened with Ad-BMP9 and SB203580 ( inhibitor of p38 MAPK signaling pathway) for 36 h respectively for the effect of the signaling pathway on osteogenic differentiation. SPSS16.0 software package was used for statistical analysis. RESULTS: Under the action of Ad-BMP9, the activity of ALP, the levels of osteopontin and osteocalcin genes were significantly higher than the control group (P<0.01). Staining of ALP and the calcium nodule deposition were consistent with the activity of ALP, the levels of osteopontin and osteocalcin. Western blot demonstrated that the expression of p-p38 and p-MKK3/6 was increased significantly. After adding SB203580, the expression of ALP, OPN and OCN was decreased significantly (P<0.01),and the calcium mineral deposits were also decreased. CONCLUSIONS: During hPDLSCs differentiation, BMP9 can induce osteogenesis, and MKK3/6-p38-MAPK pathway was involved in the osteogenesis and had positive regulation for osteogenesis of hPDLSCs.

Key words: Human periodontal ligament stem cells, Bone morphogenetic protein 9, Osteogenesis differentiation, p38 MAPK