The establishment of pulp polyp-derived mesenchymal stem cells with normal karyotype.

Background/Purpose: Pulp polyp is often eliminated as dental waste. Pulp polyp cells were reported to have high proliferation activity which might be comprised of stem cells. However, little has been known on the presence of stem cells in the pulp polyp. Moreover, pulp polyp cells might contain chromosomal abnormality. The present study was conducted to investigate the presence of pulp polyp stem cells, which could later be propagated and confirmed as normal/non-pathogenic cells using karyotype analysis. Materials and methods: Collected pulp polyps were minced, enzymatically digested, and cultured. Expression of mesenchymal stem cell (MSC) markers on pulp polyp cells were analyzed using flow cytometry. Multilineage differentiation capacity was assessed by culturing the cells in osteogenic, chondrogenic, and adipogenic differentiation media. Genomic stability of the cells was evaluated with G-banded and molecular karyotype analyses. Results: Pulp polyp cells appeared as fibroblasts-like cells. The cells were positive for cluster of differentiation (CD)105, CD90, and CD73, and negative for CD45, CD34, CD11b, CD19, and human leukocyte antigen (HLA)-DR. The cells were capable of osteogenic, chondrogenic, and adipogenic differentiation. G-banded karyotype analysis showed that there was no abnormality in the number or structure of chromosomes in pulp polyp-derived MSCs (PP-MSCs). Molecular karyotype analysis revealed that all copy number variations identified in PP-MSCs were not pathogenic. Conclusion: PP-MSCs, which fulfill the minimal criteria for MSCs and are proven to have normal karyotype, have been successfully established. PP-MSCs might be a promising and safe candidate that can be considered for pulp-dentin complex regeneration.