Effects of Tenascin-C on Dental Pulp Tissue in Mice In Vivo And on The Proliferation and Differentiation of Dental Pulp Stem Cells into Odontoblasts and Calcification In Vitro

Abstract

Kentaro Kojima, Yoshihiko Akashi, Kei Nakajima, Katsutoshi Kokubun, Seikou Shintani and Kenichi Matsuzaka

This study aimed to investigate the effects of tenascin-C (TN-C) on dental pulp tissue and on dental pulp stem cells (DPSCs). In in vivo studies, A collagen sponge with phosphate-buffered saline (PBS) for the control group or with TN-C for the experimental group was placed over the dental pulp of mice. The root pulp was excised at 7 and 21 days postoperatively and was observed microscopically using HE staining and immunohistochemistry. Inflammatory cells were found in the entire pulp tissue in the control group but no inflammatory cells were identified in the pulp tissue in the TN-C-treated experimental group. Further, nesting-positive cells at 7 days and dentin sialo phosphoprotein (DSPP)-positive cells at 21 days were seen in the experimental group. In in vitro studies, DPSCs were cultured in a medium with or without TN-C, after which the proliferation rate of DPSCs was measured mRNA expression levels were examined using quantitative reverse transcription polymerase chain reaction (qRT-PCR), and the formation of calcified nodules was investigated using alizarin red staining. There was no significant difference in the cell proliferation rate of DPSCs between the experimental and control groups during day 3 or 5, using the proliferation rate on day 1 as the baseline value. The expression of nesting mRNA on day 7 was significantly higher in the experimental group than in the control group (P<0.05), but the expression of osteocalcin (OCN) mRNA was significantly higher in the control group than in the experimental group (P<0.05). More calcified nodules formed and the area of calcified nodules in the control group was significantly greater than in the TN-C-treated experimental group on day 14 and day 21 (P < 0.05). These results suggest that TN-C regulates inflammation during the healing process in the dental pulp and induces the differentiation of dental pulp into odontoblast-like cells. Further, TN-C promotes the early differentiation of DPSCs into odontoblast-like cells, which suggests that TN-C may further contribute to the inhibition of excessive dentin formation. From the above, TN-C is involved in differentiating dental pulp into mineralized tissue-forming cells and may have a beneficial effect in treatments that utilize this function.

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