Abstract: Objective To isolate and cultivate human dental pulp stem cells (hDPSCs) from patients of different ages and compare their biological characteristics. Methods hDPSCs from patients of different ages were cultivated by the enzymatic digestion of pulp tissue method. The time when cells appeared was recorded, and their morphology was observed and compared under a microscope. Flow cytometry was used to detect surface markers of hDPSCs. Cells were induced to differentiate into odontoblasts and adipocytes in vitro. The formation of mineralized nodules and lipid droplets was observed. The CCK8 assay was used to compare the ability of cell proliferation. Moreover, mRNA levels of odontogenesis/osteogenesis related genes DSPP, OCN, RUNX2, OPN and COL-1 of different groups were detected and compared by qRT-PCR. Results hDPSCs from donors of different ages were mainly spindle-shaped. However, number of irregular cells increased with age, and there existed significant difference among the time in which cells crawled out (P<0.05). The result of flow cytometry showed that CD90 and CD73 were expressed positively, but CD146 was expressed negatively, with no expression of CD34. Mineralized nodules and lipid droplets were successfully formed in all groups under the induction of osteogenesis and lipogenesis. The CCK8 assay and qRT-PCR demonstrated that cell proliferation and the expression of odontogenic/osteogenic genes descended markedly with age (P<0.05). Conclusion hDPSCs that own multilineage differentiation potential can be obtained from pulp tissue of donors in different ages. Cell proliferation is related to age. The hDPSCs of different ages can be turned into odontoblasts/osteocytes in a certain degree. However, as the donor ages, odontogenesis/osteogenesis differentiative potential of hDPSCs decreases obviously.

Key words: human dental pulp stem cell, age-related change, vital pulp therapy, differentiation