Study on osteogenic differentiation and gene expression of human dental pulp stem cells in vitro

Objective: To investigate the capability of human dental pulp stem cells(hDPSCs) on osteogenic differentiation in vitro. Methods: hDPSCs were purified by magnetic-activated cell sorting with Stro-1 and the phenotypes were analyzed with stem cell surface markers CD29, CD44, CD90, CD105, Stro-1, CD34, CD45. hDPSCs were treated continuously with osteogenic inductive medium for 21. Alkaline phosphatase(ALP) staining, the expression levels of ALP, osteocalcin(OC), Collengen I(ColI), RunX2 genes and alizarin red staining for mineralization at different time points were analyzed.The non-induced cells were used as control. Results: Phenotype analysis indicated that hDPSCs were positive for mesenchyme stem cell markers CD29, CD44, CD90, CD105, Stro-1, and negative for hematopoietic stem cell markers CD34,CD45. Compared with the control group, the ALP staining of the cells in induced group were significantly higher at day 5,7, 14 and only the induced cells could form mineralized nodes as shown by alizarin red staining on Day 21. The expression of the ALP, ColI, RunX2, OC genes were positive in induced group. Conclusion: Human DPSCs selected by Stro-1 have the potential of differentiation into osteoblasts under osteogenic culture and forming mineralized nodes. Osteoblast markers(ALP, OC, ColI, RunX2 etc) participated in the osteogenic differentiation of hDPSCs.