Effect of Small-molecule GSK3 Antagonist on Differentiation of Rat Dental Pulp Cells into Odontoblasts

It has been reported that glycogen synthase kinase 3 (GSK3) antagonist promoted the reparative formation of dentin. The aim of the present study was to evaluate whether treatment schedule of Tidegrusib® (TG), a small-molecule GSK3 antagonist, affected in vitro differentiation of dental pulp cells toward odontoblast-like cells.

Pulp cells isolated from rat incisors were repeatedly exposed to TG for the first 6 h (intermittent exposure) or the full 48 h (continuous exposure) of each 48-h incubation cycle. Histological analysis of alkaline phosphatase and von Kossa staining were performed. The expression of dentin sialophosphoprotein (Dspp) and osteocalcin (Ocn) mRNA were examined by real-time polymerase chain reaction. Western blotting assays were used to monitor the expression of β-catenin and its phosphorylated form.

When pulp cells were intermittently exposed to TG for only the first 6 h of each incubation cycle, pulp cells differentiated into odontoblast-like cells, characterized by an increase in alkaline phosphatase activity, nodule formation, and mRNA expression of Dspp. and Ocn; this did not occur under the continuous exposure. Phosphorylation of β-catenin was enhanced by continuous exposure to TG compared with intermittent exposure.

These results suggest that the TG-induced odontoblast-like cell differentiation reflects in vivo reparative dentin formation and depends on the exposure time.