Effects of inorganic phosphate on stem cells isolated from human exfoliated deciduous teeth

Calcium phosphate-based materials (CaP) are introduced as potential dental pulp capping materials for deciduous teeth. The present study investigated the influence of inorganic phosphate (P_i) on regulating stem cells isolated from human exfoliated deciduous teeth (SHED). SHEDs were treated with P_i. Cell cycle progression and apoptosis were examined using flow cytometry analysis. Osteo/odontogenic and adipogenic differentiation were analyzed using alizarin red S and oil red O staining, respectively. The mRNA expression profile was investigated using a high-throughput RNA sequencing technique. P_i increased the late apoptotic cell population while cell cycle progression was not altered. P_i upregulated osteo/odontoblastic gene expression and enhanced calcium deposition. P_i-induced mineralization was reversed by pretreatment of cells with Foscarnet, or p38 inhibitor. P_i treatment inhibited adipogenic differentiation as determined by decreased PPARγ expression and reduced intracellular lipid accumulation. Bioinformatic analysis of gene expression profiles demonstrated several involved pathways, including PI3K/AKT, MAPK, EGFR, and VEGF signaling. In conclusion, P_i enhanced osteo/odontogenic but inhibited adipogenic differentiation in SHED.