Comparison of P75 NTR-positive and -negative etcomesenchymal stem cell odontogenic differentiation through epithelial-mesenchymal interaction.

The aim of this study was to investigate differences of odonto-differentiation between P75 -neurotrophin receptor (P75 -NTR)-positive ectomesenchymal stem cells (P75+EMSCs) and P75 -NTR-negative ectomesenchymal stem cells (P75-EMSCs), and their underlying mechanisms.Primary cranial neural crest-derived cells (CNC) were isolated from the first branchial arches, and P75+EMSCs and P75-EMSCs were sorted by fluorescence-activated cell sorting. Differentiation of P75+EMSCs or P75-EMSCs into odontoblast-like cells was induced by dental epithelial cells in vitro or in vivo. Differential gene expression profiles between P75+EMSCs and P75-EMSCs were analysed by microarray assay. Smad4-specific small interfering RNA and activator kartogenin were used to treat the cells, to evaluate effects of Smad4 in odonto-differentiation of P75+EMSCs or P75-EMSCs.Under induction of dental epithelium conditioned medium, P75+EMSCs had more mineralized node formation and higher expression of Dmp1 and Dspp compared to P75-EMSCs. In our in vivo study, graft of P75+EMSCs recombination with dental epithelium showed higher expression of DMP1 and DSP. Knock-down of Smad4 in P75+EMSCs significantly downregulated expression of DMP1 and DSP, while activation of Smad4 in P75-EMSCs by the activator kartogenin, significantly increased DSP and DMP1 expression.P75+EMSCs showed more odonto-differentiation potential than P75-EMSCs both in vivo and in vitro. Smad4 played a critical role in determination of odonto-differentiation potential of CNC-derived EMSCs.