Assessment of stem cell markers in multipotent dental pulp cells

Objectives: We previously reported that rat and mouse dental pulp-derived cells can differentiate into osteogenic, neurogenic and myogenic lineage cells. The aim of the present study was to identify possible markers for the multipotent dental pulp-derived cells. Methods: To achieve this, we performed in vitro adipogenic differentiation of rat dental pulp-derived cells, and compared the changes in expression of stem cell markers such as Oct-3/4, Sox2 and Nanog in the dental pulp-derived cells during the induction of differentiation with those in the 3T3 L1 adipocyte progenitor cell line. Insulin, 3-isobutyl-1-methylxanthine and dexamethasone were added to induce adipogenesis. Results: Dental pulp-derived cells containing lipid droplets were observed after the induction, similar to the case for 3T3 L1 cells. Oct-3/4, Sox2 and Nanog were expressed in both types of cells during culture in basal medium. In 3T3 L1 cells after the induction of differentiation, the levels of Oct-3/4 and Sox2 expression were significantly decreased to 25% and 30%, respectively (p<0.01), while the level of Nanog did not change significantly during the differentiation. In the dental pulp-derived cells, the expression patterns of Sox2 and Nanog during the differentiation were similar to those in 3T3 L1 cells. Interestingly, the expression of Oct-3/4 was transiently increased at 1 week after the induction and then significantly decreased (p<0.01). Conclusion: These findings suggest that Oct-3/4 and Sox2 may be better markers for assessing differentiation than Nanog, because it is also known that Nanog is not a defining factor in inducible pluripotent stem cells derived from somatic cells. Therefore, assessment of Oct-3/4 and Sox2 in rat dental pulp-derived cells during the induction of differentiation could be useful for future regenerative medicine applications. This study was supported in part by JSPS KAKENHI (21592547) and by MEXT HAITEKU (2007-2011).