Fig. 6
mTORC1 regulated the release of exosomes by odontoblasts to specifically inhibit DPSC odontoblastic differentiation. A, B DPSCs were incubated with 105 particles/mL, 106 particles/mL, 107 particles/mL and 108 particles/mL exosomes that were isolated from MDPC23 cells, and then, the cell lysates were assessed by western blotting. The results showed that the protein expression levels of the odontoblastic markers ALP, COL and DMP1 gradually decreased as the exosome concentration increased, and 108 particles/mL notably inhibited the expression of ALP, COL and DMP1. Full-length blots are presented in Additional file 1: Figure S6. C qRT‒PCR analysis indicated that the miRNA expression levels of ALP, COL and DMP1 were negatively correlated with the concentration of exosomes (n = 3). D ALP activity staining of DPSCs that were treated with 105 particles/mL, 106 particles/mL, 107 particles/mL and 108 particles/mL exosomes that were isolated from MDPC23 cells (scale bar = 400 μm). E The formation of mineralized nodules was examined by Alizarin Red S staining, and the results showed that the formation of mineralized nodules was gradually reduced when the concentration of exosomes was increased, and the formation of mineralized nodules was obviously inhibited at an exosome concentration of 108 particles/mL (scale bar = 400 μm). The values are presented as the means ± SDs. *p < 0.05, **p < 0.01, ***p < 0.001. DPSCs Dental pulp stem cells, ALP alkaline phosphatase