Characterization of primary dental pulp cells in vitro.

PURPOSE

This study's purpose was to characterize dental pulp cells from human primary teeth and determine their ability to induce differentiation of oral epithelial cells.

METHODS

Dental pulp cells were isolated from freshly extracted primary incisors, digested with 4 mg/ml collogenase/dispase, and grown in Dulbecco's modified Eagle's medium with 10 percent fetal bovine serum. Stem cell populations were identified by immunocytochemical staining for STRO-1 and CD146 and fluorescence activated cell sorting. To determine whether primary pulp cells can signal epithelium, the pulp cells were grown in coculture with human fetal oral epithelial cells. After 3 days, the cocultured cells were collected and analyzed for amelogenin expression by polymerAse chain reaction (PCR) and immunocytochemical staining.

RESULTS

Immunofluorescence and fluorescence activated cell sorting of STRO-1+ cells showed this stem cell population to be approximately 2 percent of the total population. Growth-arrested primary dental pulp cells grown in coculture with oral epithelial cells showed expression of Amelogenin by immunocytochemistry and PCR. Oral epithelial cells alone were amelogenin immunonegative.

CONCLUSIONS

Primary tooth dental pulp cells contain less than 2 percent stem cells. Cells within the primary tooth pulp can promote epithelial cell differentiation toward an ameloblast phenotype, suggesting the potential use of this heterogeneous population of cells in cell-mediated enamel tissue engineering.