Exploring Stem Cells from Clinically Compromised Dental Pulp

Objective: Although human dental pulp stem cells (DPSCs) isolated from healthy teeth have been extensively characterized, it is unknown whether DPSCs also exist in clinically compromised teeth with pulpitis. Here we explore the cellular property and proliferation competence of potential DPSCs from clinically compromised dental pulp to set a basis for future stem cell based pulp therapy via endogenous regeneration.

Methods: Pulp cells were isolated from permanent healthy teeth extracted for orthodontics (healthy group) and teeth with irreversible pulpitis undergoing root canal therapy (diseased group) in patients aged 7-40. Cell proliferation competence was evaluated by frequencies of single cell-derived colony formation in primary passages and by BrdU proliferation assay in expanded passages. The potential progenitor cell population was evaluated by expression of stromal stem cell marker (Stro-1) via flow cytometry.

Results: The patient age was 24.6±6.1 years (mean± S.E.) in the healthy group (n=8) and 21.8±8.4 years in the diseased group (n=8). Pulp cells from all healthy samples were successfully cultured and formed single cell-derived colonies. In the diseased group, the percentage of success in cell culture and colony formation was 87.5% and 75% respectively. Average colony formation frequency was 35.96±26.09 and 4.71±5.90 (mean± S.D.) per well in the healthy and diseased groups respectively. Healthy pulp cells showed a higher proliferation compared with disease pulp cells in expanded passages as evaluated by BrdU assay. Cells from diseased group had a slightly but not statistically significantly higher percentage of Stro-1 positive population than healthy group.

Conclusion: Even severely clinically compromised dental pulp contains viable cells with the potential for ex vivo expansion and proliferation with a similar percentage of Stro-1 positive cells. This strongly suggests the existence of functional DPSCs in inflamed dental pulp tissue that could benefit pulp tissue regeneration.

Supported by NIH 1T32DE017245