Gene-Expression Profile of Dental Pulp Cells During Differentiation Into an Adipocyte Lineage

Gene regulation during in vitro differentiation into adipocytes was examined in rat dental pulp–derived cells. Insulin, 3-isobutyl-1-methylxanthine, and dexamethasone were added to induce adipogenesis. Cells containing lipid droplets were observed after induction as in 3T3 L1 cells. Rat dental pulp–derived cells showed their potential to differentiate into adipocytes in vitro. In both types of cells, the pluripotent markers <I>Oct-3/4</I> and <I>Sox2</I> were downregulated during differentiation, whereas the expression of <I>Nanog</I> was not significantly changed during differentiation. Interestingly, in the dental pulp–derived cells, the level of <I>Oct-3/4</I> was transiently induced at 1 week after induction and then significantly decreased during differentiation. Based on the expression profiles determined using GeneChip Arrays, 3418 probes across 10 clusters showed a difference in expression at 1, 2, and 3 weeks after induction versus before induction. Notably, genes in the PPAR signaling pathway including <I>Pparγ</I>, <I>Fabp4</I>, and the <I>C/EBP</I> family were upregulated by more than 3-fold. Upregulation of the PPAR pathways seems to be a critical signal transduction pathway in this differentiation system. These findings indicate that dental pulp–derived cells are a potential source of adipogenic cells, and their gene expression profile could be useful in future regenerative medicine applications.