WIF1 enhanced dentinogenic differentiation in stem cells from apical papilla

BACKGROUND: Odontogenic mesenchymal stem cells (MSCs) isolated from tooth tissues are a reliable resource that can be utilized for dental tissue regeneration. Exploration of the mechanisms underlying the regulation of their differentiation may be helpful for investigating potential clinical applications. The stem cell niche plays an important role in maintaining cell functioning. Previous studies found that Wnt inhibitory factor 1 (WIF1) is more highly expressed in apical papilla tissues than in stem cells from apical papilla (SCAPs) using microarray analysis. However, the function of WIF1 in SCAPs remains unclear. In the present study, we investigated the function of WIF1 during dentinogenic differentiation in SCAPs. METHODS: A retrovirus containing HA-WIF1 was used to overexpress WIF1 in SCAPs. Using Western blot analysis, we verified the expression of HA-WIF1. Alkaline phosphatase (ALP) activity assays, Alizarin Red staining and quantitative calcium analysis were performed to investigate the in vitro potential for dentinogenic differentiation in SCAPs. The expression of dentinogenesis-associated genes DSPP, DMP1, Runx2 and OSX were assayed using real-time RT-PCR. Transplantation experiments were used to measure dentinogenesis potential in vivo. RESULTS: The real time RT-PCR results showed that WIF1 was more highly expressed in apical papilla tissues than in SCAPs, and its expression was increased during the process of dentinogenic differentiation. Overexpression of WIF1 enhanced ALP activity and mineralization in vitro, as well as the expression of DSPP, DMP1 and OSX in SCAPs. Moreover, in vivo transplantation experiments revealed that dentinogenesis in SCAPs was enhanced by WIF1 overexpression. CONCLUSION: These results suggest that WIF1 may enhance dentinogenic differentiation potential in dental MSCs via its regulation of OSX and identified potential target genes that could be useful for improving dental tissue regeneration.