HDAC Inhibitor Trichostatin A Promotes Proliferation and Odontoblast Differentiation of Human Dental Pulp Stem Cells

Abstract

Trichostatin A (TSA) is a potent histone deacetylases (HDAC) inhibitor with a broad spectrum of epigenetic activities known to regulate diverse cellular mechanisms including differentiation of mesenchymal stem cells. In this study, we demonstrate that TSA promotes proliferation and odontoblast differentiation of human dental pulp stem cells (hDPSCs) in vitro and has the ability to enhance dentin formation and odontoblast differentiation in vivo during tooth development. We observed that TSA increased the expression of proliferating cell nuclear antigen (PCNA) and Cyclin D1 in hDPSCs at a certain concentration and the activation of JNK/c-Jun pathway was essential for TSA-dependent hDPSCs proliferation. Furthermore, TSA accelerated mineral nodule formation in vitro and increased gene expression of dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1), bone sialoprotein (BSP) and osteocalcin (OCN). In addition, TSA significantly up-regulated the levels of phospho-Smad2/3, Smad4, and NFI-C, while SIS3, the specific inhibitor of Smad3, inhibits TSA enhancing mineralization differentiation of hDPSCs. HDAC3 is down-regulated by TSA treatment, suggesting a possible mediator of TSA-dependent pathways among the members of HDAC family. Moreover, TSA injected embryos exhibited increased dentin thickness, larger dentin areas and higher odontoblast numbers in their postnatal molars with stronger DSP expression in immunohistochemical staining. These findings indicate that TSA may serve a key role in proliferation and odontoblast differentiation of hDPSCs in dental developmental stages and can be used as an accelerator in dental hard tissue engineering.