Histone Deacetylase Inhibitors Induce Differentiation in Preodontoblasts Cell Line

Objectives: Calcium hydroxide agents have been widely used as pulp conservative treatment. Some improvements are required for the better quality of the formed dentin and the shorter times to dentin formation. Histone deacetylase inhibitors (HDACi) involved in epigenetic modifications promoted osteoblastic differentiation and inhibited osteoclast differentiation. It is, however, still not known whether HDACis promote odontoblastic differentiation. In this study, we examined whether HDACi promoted odontoblast differentiation in vitro.
Methods: MDPC23 cells were used as a model of odontoblastic cells. The cells were grown in DMEM supplemented with 10% fetal bovine serum. MDPC23 was incubated with HDACis for 24hr. As HDACis, we used MS-275 (0.01, 0.1, 1, 10 μM) , sodium valproate; (VPA; 0.01, 0.1, 1, 10 mM), trichostatin A (TSA; 1, 10, 100, 1000 nM), and butyric acid (NaB, 0.01, 0.1, 1, 10 mM, Sigma-Aldrich). No treatments were used as the controls. Expression levels of Bmp2，Bmp4，Bmp6，Runx2，Alpl，Bglap，Spp1，Dspp and Dmp1 mRNAs were evaluated by quantitative RT-PCR. Results were compared by Kruskal-Wallis test with p < 0.05 accepted as statistically significant. ALPase and Alizarin Red staining were carried out to monitor differentiation and mineralization in MDPC23 for 6 days.
Results: The expression levels of Runx2, Alp1, BMP-4 and-6 were significantly higher in the cells stimulated with MS-275, VPA and NaB than in the control. These HDACi promoted calcifications confirmed by ALPase and Alizarin Red staining in the cultures.
Conclusions: The results indicate that HDACis may promote differentiation of odontoblastic cells and induce their calcification. Some of HDACis may be useful agents for pulp conservative treatment.