Erythropoietin induces odontoblastic differentiation of human-derived pulp stem cells via EphB4-Mediated MAPK signaling pathway

Objectives: Human-derived pulp stem cells play key roles during dentinogenesis. Erythropoietin is reportedly involved in osteoblastogenesis and facilitates bone formation. However, the mechanism is still unknown. This research was to study the potential of erythropoietin in enhancing odontoblastic differentiation of human-derived pulp stem cells and to determine the underlying mechanism.

Methods: The human-derived pulp stem cells were treated with erythropoietin, EphB4 inhibitor, and MAPK inhibitors, and the odontoblastic differentiation was measured by ALP staining, ALP activity assay, alizarin red S staining, and their quantitative analysis, and RT-qPCR of DSPP, DMP1, OCN, and RUNX2. The direct pulp capping model was established to evaluate the formation of tertiary dentin after treatment with erythropoietin. Western blot assay was conducted to assess relevant protein expressions in the phosphorylated EphB4 and MAPK pathway.

Results: The results showed that erythropoietin promoted odontoblastic differentiation of human-derived pulp stem cells at 20 U/ml. Erythropoietin induced tertiary dentin formation in vivo. The potential mechanism of this was upregulating phosphorylated EphB4 and phosphorylated MAPK; furthermore, this effect could be decreased by EphB4 inhibitors, which inhibited MAPK phosphorylation. Blockage of MAPK pathways attenuated human-derived pulp stem cells' odontoblastic differentiation, suggesting that MAPK pathways are involved.

Conclusion: Erythropoietin induced tertiary dentin formation in vivo. And erythropoietin enhanced human-derived pulp stem cells' odontoblastic differentiation via the EphB4-mediated MAPK signaling pathway.