The effect of in vitro osteogenic induction on in vivo hard tissue forming potential of the dental pulp stromal cells from deciduous teeth

Abstract

Human dental pulp tissue of deciduous teeth has been considered as a source of multipotent stem cells, and there have been many attempts for its application in dentin or bone regeneration. The objective of this study was to examine the effect of in vitro osteogenic induction of deciduous dental pulp stromal cells (DDPSCs) on their in vivo hard tissue forming potential. DDPSCs were isolated from extracted deciduous teeth using outgrowth method. During ex vivo expansion, DDPSCs were exposed to osteogenic stimuli for different time periods (4 and 8 days) while the control group was expanded without osteogenic stimuli. First, in vitro differentiation pattern was investigated using alkaline phosphatase (ALP) staining and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Then the ex vivo expanded and differentiated DDPSCs were subcutaneously transplanted into immune-compromised mice with macroporous biphasic calcium phosphate (MBCP) as a carrier. The results in in vivo transplantation were analyzed by quantitative RT-PCR, ALP activity assessment, histological analysis, and immunohistochemical staining. The amount of hard tissue was greatest in Day 4 group, followed by Day 8 and the control group. The hard tissue generated in Day 8 group presented most bone-like morphology among the three groups, while the control group featured more dentin-like characters. 4-day induction period in the osteogenic media was related to greater potential to form hard tissue, whereas 8-day induction period was related to formation of more bone-like hard tissue. In conclusion, in vitro osteogenic induction of DDPSCs enhanced hard tissue formation in vivo and also altered character of the newly generated hard tissue.