Stromal-derived Factor-1α signaling is involved in bone morphogenetic protein-2-induced odontogenic differentiation of stem cells from apical papilla via the Smad and Erk signaling pathways

Stromal-derived factor-1α (SDF-1α) is a chemokine signaling molecule that binds to the transmembrane receptor CXC chemokine receptor-4 (CXCR4) and carries out important functions in development tissue homeostasis. SDF-1α signaling via CXCR4 regulates the recruitment of stem and precursor cells to support tissue-specific repair or regeneration. In this study, we examined the contribution of SDF-1α signaling to the odontogenic differentiation of stem cells from the apical papilla (SCAP) induced by bone morphogenic protein 2 (BMP-2). CXCR4 expression was detected in cultured SCAP and SDF-1α promoted the migration of SCAP in Transwell assays. Blocking SDF-1α signaling by treatment with siRNA significantly affected BMP-2-induced mineralized nodule formation and alkaline phosphatase (ALP) activity. Moreover, blocking SDF-1α signaling inhibited the BMP-2-induced early expression of runt-related factor-2 (Runx-2) and strongly suppressed the induction of dentin matrix protein 1 (DMP-1) and dentin sialophosphoprotein (DSPP) expression by BMP-2. Furthermore, the interaction between SDF-1α and BMP-2 signaling was mediated via intracellular Smads and Erk activation. In conclusion, our results demonstrated that SDF-1α can significantly promote the migration of SCAP. Moreover, we revealed corequirement of the SDF-1α/CXCR4 signaling pathways in the BMP-2-induced odontogenic differentiation of SCAP, and these findings may be applied in new strategies for dental pulp regeneration.