Abstract
In recent years, stem cells have been studied for treating tooth loss. The present study aimed to investigate the roles of dentin non-collagen protein (DNCP)-associated microenvironments in the differentiation of induced pluripotent stem cells (iPSCs) into dentin cells. iPSCs were cultured and identified by examining octamer-binding transcription-factor-4 (Oct-4) and sex-determining region-Y-2 (Sox-2) expression. iPSCs were differentiated by culturing DNCP-associated microenvironments (containing specific growth factors), and they were divided into control, DNCP, DNCP+bone morphogenetic proteins (BMPs) and DNCP+Noggin (a BMP inhibitor) groups. Msh homeobox 1 (Msx-1), dentin sialophosphoprotein (DSPP) and dentin matrix protein 1 (DMP-1) mRNA expression was evaluated using reverse transcription-quantitative PCR. The levels of p38, phosphorylated (p)-p38, Smad and p-Smad were determined by western blotting. Upon treatment with mouse embryonic fibroblasts, iPSCs-dependent embryoid bodies (EBs) were successfully generated. iPSCs exhibited increased Oct-4 and Sox-2 expression. Differentiated iPSCs had higher expression levels of DSPP, DMP-1 and Msx-1 in the DNCP group compared with those in the control group (P<0.05). Noggin treatment significantly downregulated, while BMPs administration significantly increased the expression levels of DSPP, DMP-1 and Msx-1 compared with those of the DNCP group (P<0.05). The ratios of p-p38/p38 and p-Smad/Smad were significantly higher in the DNCP group compared with those in the control group (P<0.05). Noggin and BMPs significantly decreased ratios of p-p38/p38, compared with those of the DNCP group (P<0.05). In conclusion, DNCP induced the differentiation of iPSCs into odontoblasts by activating the Smad/p-Smad and p38/p-p38 signaling pathways.