Nel-like Molecule 1 Contributes to the Odontoblastic Differentiation of Human Dental Pulp Cells
Mengmeng Liu1, Qiang Wang2, Ronghua Tang1
1Shandong Provincial Key Laboratory of Oral Biomedicine, School and Hospital of Stomatology, Shandong University, Jinan, Shandong, China.
Introduction:
Nel-like molecule-1 (Nell-1) with epidermal cell growth factor-like coding structures is a recently discovered secreted protein that can specifically induce osteoblast differentiation, bone formation, and bone regeneration. The expression and localization of Nell-1 during murine molar development suggest that this protein participates in odontoblastic differentiation. This study aims to assess the expression of Nell-1 in the pulp-dentin complex of human teeth and determine the effect of human recombinant Nell-1 (hrNell-1) on odontoblastic differentiation of cultured human dental pulp cells.
Methods:
Immunohistochemical assay was performed to detect the expression and location of Nell-1 in healthy human teeth. The activity of alkaline phosphatase in human dental pulp cells stimulated by hrNell-1 was examined. Moreover, the expression of related odontoblastic markers was evaluated using quantitative real-time polymerase chain reaction and Western blot.
Results:
Immunohistochemical results showed that Nell-1 was primarily expressed in the odontoblasts (odontoblastic bodies and processes), pulp fibroblasts, and endothelial cells of the blood vessels in human teeth. In vitro experiments showed that hrNell-1 could increase the activity of alkaline phosphatase and enhance the expression of important odontoblastic markers including osteopontin and dentin matrix protein 1 in cultured human dental pulp cells.
Conclusions:
Nell-1 plays a role in odontoblastic differentiation of human dental pulp cells and dentin formation.
