Human dental pulp stem/progenitor cells (hDPSCs) are attractive candidates for regenerative therapy because they can be easily expanded to generate colony-forming unit-fibroblasts (CFU-Fs) on plastic and the large cell numbers required for transplantation. However, isolation based on adherence to plastic inevitably changes the surface marker expression and biological properties of the cells. Consequently, little is currently known about the original phenotypes of tissue precursor cells that give rise to plastic-adherent CFU-Fs. To better understand the in vivo functions and translational therapeutic potential of hDPSCs and other stem cells, selective cell markers must be identified in the progenitor cells. Here, we identified a dental pulp tissue-specific cell population based on the expression profiles of 2 cell-surface markers LNGFR (CD271) and THY-1 (CD90). Prospectively isolated, dental pulp-derived LNGFR(Low+)THY-1(High+) cells represent a highly enriched population of clonogenic cells--notably, the isolated cells exhibited long-term proliferation and multilineage differentiation potential in vitro. The cells also expressed known mesenchymal cell markers and promoted new bone formation to heal critical-size calvarial defects in vivo. These findings suggest that LNGFR(Low+)THY-1(High+) dental pulp-derived cells provide an excellent source of material for bone regenerative strategies.

Dental pulp stem cells/progenitor cells (DPSCs) can be easily obtained and can have excellent proliferative and mineralization potentials. Therefore, many studies have investigated the isolation and bone formation of DPSCs. In most previous reports, human DPSCs were traditionally isolated by exploiting their ability to adhere to plastic tissue culture dishes. DPSCs isolated by plastic adherence are frequently contaminated by other cells, which limits the ability to investigate their basic biology and regenerative properties. Additionally, the proliferative and osteogenic potentials vary depending on the isolated cells. It is very difficult to obtain cells of a sufficient quality to elicit the required effect upon transplantation. Considering clinical applications, stem cells used for regenerative medicine need to be purified in order to increase the efficiency of bone regeneration, and a stable supply of these cells must be generated. Here, we review the purification of DPSCs and studies of cranio-maxillofacial bone regeneration using these cells. Additionally, we introduce the prospective isolation of DPSCs using specific cell surface markers: low-affinity nerve growth factor and thymocyte antigen 1.

We investigated cell response, including cell proliferation and expression of heat stress protein to clarify the influence of low-level (Ga-Al-As diode) laser irradiation on rat parotid gland acinar cell-derived Par-C10 cells. Furthermore, we also investigated amylase release and cell death to irradiation in rat parotid gland acinar cells. Number of Par-C10 cells in the laser-irradiated groups was higher than that in the non-irradiated group at days 5 and 7, although the difference was statistically significant (p<0.01).Higher expression of HSP25 and bcl-2 was seen at days 1 and 3 in the irradiated group.Amylase release assay showed no significant difference between irradiated group and non-irradiated group statistically. Trypan blue exclusion assay revealed that there was no difference in the ratio of dead to live cells between the irradiated-and non-irradiated groups. These results suggest that low-level laser irradiation promotes cell proliferation and expression of anti-apoptosis proteins in Par-C10 cells, but it does not significantly affect amylase secretion and does not induce rapid cell death in isolated rat parotid gland acinar cells.3

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