Characterization of primary dental pulp cells in vitro.

Abstract

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.