EGFL6 Promotes Angiogenesis and Odontogenesis in Pulp Regeneration via MAPK Signaling Pathways.

Objectives: Epidermal growth factor-like domain-containing protein 6 (EGFL6) is a member of the epidermal growth factor superfamily. It has been reported that it can enhance the osteogenic differentiation potential of stem cells and stimulate angiogenesis. However, its effects on the regulation of odontogenic differentiation of dental pulp stem cells (DPSCs) have not been studied. Therefore, we aimed to investigate the role of EGFL6 in pulp regeneration and its underlying mechanism.

Methods: The cytotoxicity and migration-inductive ability of EGFL6 were evaluated using cell counting kit-8 assay and transwell assay, respectively. A tube formation assay was performed to assess the angiogenic effect of EGFL6. The alkaline phosphatase (ALP) and alizarin red S staining were conducted for mineralization evaluation. The odontoblastic-related and angiogenesis-related markers were measured by quantitative real-time polymerase chain reaction and Western blot analysis. Western blot was also conducted to further examine the levels of key factors involved in MAPK signaling pathways.

Results: EGFL6 displayed no cytotoxicity and was capable of promoting cell migration and angiogenesis. Besides, EGFL6 enhanced the mineralization process and up-regulated the expression levels of odontoblastic-related markers (DSPP, DMP1, and BSP) after 5, 7, and 10 days. The expression levels of odontoblastic-related and angiogenesis-related proteins (DSPP, DMP1, VEGF, and ALP) could all be up-regulated by EGFL6. There was also an increase in the phosphorylation levels of ERK1/2 and P38.

Conclusion: EGFL6 can promote the migration, angiogenesis, and odontogenesis differentiation of DPSCs via the activation of MAPK signaling pathways.