01/19/2011 Characterization of Primary Dental Pulp Cells In Vitro

Resident: J. Hencler
Date: 01/19/2011

Article title: Characterization of Primary Dental Pulp Cells In Vitro
Author(s): Coppe et al
Journal: Pediatric Dentistry V31/NO7 NOV/DEC09

Major topic: Potential of pulp stem cells
Type of Article: Scientific

Main Purpose:
Characterize dental pulp cells from human primary teeth and determine their ability to induce differentiation of oral epithelial cells

Overview of method of research:
Dental pulp cells were isolated from freshly extracted primary incisors, digested w/ collagenase/dipase and grown in medium w/ 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 w/ human fetal oral epithelial cells (OECs). After 3 days, the cocultured cells were collected and analyzed for amelogenin expression by PCR and immunocytochemical staining.

Findings:
Immunofluorescence and fluorescence activated cell sorting of STRO-1 positive cells showed this stem cell population to be approximately 2% of the total population. Growth-arrested primary dental cells grown in coculture w/ OECs showed expression of amelogenin by immunocytochemistry and PCR. OECs were alone amelogenin immunonegative.

Key points in the article discussion:
The finding that human primary teeth contain multipotent stem cells has generated much interest in their potential use as a resource for stem cells to repair damaged tooth structures. Stem cells from human exfoliated deciduous teeth (SHEDs) were found to express STRO-1 and CD146, two early mesenchymal stem cell markers. The stem cell populations from primary teeth were found to have a higher proliferation rate than those from permanent teeth. Although primary human teeth contain stem cell populations, this is a minor component of the pulp cell population. Only 2% of the total primary cell population was found to be STRO-1 positive suggesting a relatively small population of stem cells within the primary tooth pulp. Although the authors report it was difficult to isolate pure stem cell populations from the primary tooth pulp, the upregulation of amelogenin in OECs when grown in coculture with the dental pulp cells from primary teeth (pDPCs), which includes a heterogeneous cell population of cells, suggests that these stem cells may not be necessary in large numbers to promote epithelial cell differentiation. The relatively few numbers of available pulp stem cells, the challenges in harvesting those stem cells, and the likely possibility that pulp stem cells are hematopoetically derived and could be much more easily obtained from blood or bone marrow, suggest that it is unlikely that dental pulp stem cells would be a primary source of cells for regeneration of other tissues. The ability of primary pulp stem cells to promote generation of tooth structures, including dentin and enamel, is more promising. Future research should include isolation and characterization of homogeneous populations of cells with in the dental pulp and their ability to regeneration tooth structures.

Summary of conclusions:
Mesenchymal stem cells can be isolated from primary tooth pulps. This heterogeneous population of cells can promote differentiation of fetal OECs into ameloblast lineage cells.

Assessment of article:
Good article with promising results. Good study design using many difficult microscopic and cell culturing techniques. The isolation of dental pulp cells from extracted primary teeth w/ moderate to severe caries may have had an effect on the numbers and viability of the stem cell line isolated in this study. Interesting stuff.