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. (Pediatr Dent 2009;31:467-71) Received July 28, 2008 Lost Revision December 2, 2008 vertical bar Revision Accepted January 27 2009