Human Dental pulp stem cells (hDPSCs): Isolation, enrichment and comparative differentiation of two sub-populations Integrative control of development

Background: Human dental pulp represents a suitable alternative source of stem cells for the purpose of cell-based therapies in regenerative medicine, because it is relatively easy to obtain it, using low invasive procedures. This study characterized and compared two subpopulations of adult stem cells derived from human dental pulp (hDPSCs). Human DPSCs, formerly immune-selected for STRO-1 and c-Kit, were separated for negativity and positivity to CD34 expression respectively, and evaluated for cell proliferation, stemness maintenance, cell senescence and multipotency. Results: The STRO-1⁺/c-Kit⁺/CD34⁺ hDPSCs showed a slower proliferation, gradual loss of stemness, early cell senescence and apoptosis, compared to STRO-1⁺/c-Kit⁺/CD34^- hDPSCs. Both the subpopulations demonstrated similar abilities to differentiate towards mesoderm lineages, whereas a significant difference was observed after the neurogenic induction, with a greater commitment of STRO-1⁺/c-Kit⁺/CD34⁺ hDPSCs. Moreover, undifferentiated STRO-1⁺/c-Kit⁺/CD34^- hDPSCs did not show any expression of CD271 and nestin, typical neural markers, while STRO-1⁺/c-Kit⁺/CD34⁺ hDPSCs expressed both. Conclusions: These results suggest that STRO-1⁺/c-Kit⁺/CD34^- hDPSCs and STRO-1⁺/c-Kit⁺/CD34⁺ hDPSCs might represent two distinct stem cell populations, with different properties. These results trigger further analyses to deeply investigate the hypothesis that more than a single stem cell population resides within the dental pulp, to better define the flexibility of application of hDPSCs in regenerative medicine.