Figure 1.

hDPSCs were treated with DPSC-EXO (5 μg/mL) for one week, in vitro. Quantitative gene expression analysis demonstrates upregulation of genes characteristic of odontogenic differentiation in DPSC-EXO-treated hDPSCs, compared to untreated hDPSCs (A). Upregulated odontogenic gene expression corroborates with calcium mineral ization by treated and untreated hDPSCs over the course of two weeks, demonstrated by colorimetric assay (B). In the same fashion, hDPSCs were treated with MDPC-EXO (5 μg/mL) which showed similar characteristic upregulation in dentinogenic gene expression after 1 week (C). MDPC-EXO (5 μg/mL) induced significantly more mineralization after two weeks than DPSC-EXO, in vitro, measured by colorimetric assay (D) and visualized by alizarin red staining (E). To probe the mechanism by which MDPC-EXO upregulate the dentinogenic differentiation trajectory, Western blot analysis demonstrates increased Erk1/2 phosphorylation in a time-dependent (F) and dose-dependent (G) manner, which leads to upregulation of RUNX2 protein expression. Treatment with U0126, an inhibitor of MAPK signaling, was used to confirm the role of MAPK signaling in the MDPC-EXO-mediated upregulation of RUNX2 (H, I, J). * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001.