Characteristics of Single Colony-Derived Progenitor Cells from Deciduous Pulp

Objectives: Many studies have successfully isolated stem cells from dental pulp, however dental pulp is heterogeneous with respect to cell type. To begin to understand the cellular heterogeneity of human dental pulp, we compared the characteristics of cells expanded from single colonies, isolated from deciduous dental pulp. Methods: Cells were isolated from deciduous human dental pulp by enzymatic dissociation. Single colonies were counted on day 7, 9 and 11 post-seeding. Eight single colonies were selected from deciduous pulp pooled from 3 separate donors. Expanded cultures from each single colony were assessed for proliferation, and differentiation into osteogenic/dentinogenic, chondrogenic and adipogenic lineages. Phenotype was assessed by reverse transcriptase-PCR for mesenchymal stem cell genes: CD105, CD90, CD73, CD34, CD45, CD19, CD11B and HLA-DR, at passage 6, 10 and 15. Results: Colonies appeared on day 7 post-seeding and had increased in number by day 9 and 11 post-seeding. Cultures from all single colonies showed a total population doubling of >20. The median total population doubling for single colonies was 40. All single colonies expressed CD105, CD90 and CD73 but showed no expression of CD34, CD45, CD19 or CD11B. This pattern of expression was observed at passage 6, 10 and 15. Positive expression of HLA-DR was observed in 5 out of 8 single colonies. Osteogenic/dentinogenic, adipogenic and chondrogenic differentiation was observed in 3/6, 1/6 and 4/5 single colonies, respectively. Colony 3 alone differentiated into all 3 lineages. Conclusions: Progenitor cell colonies from deciduous dental pulp are heterogeneous with respect to proliferation and differentiation. The heterogeneity of deciduous dental pulp progenitor cells is an important factor to consider when exploring the use of these cells for tissue repair strategies.