Abstract: Objective： To get the stem cells from the young permanent tooth apical papillae, and observe the osteogenic differentiation of the cells after cultured with acellular dermal matrix (ADM). Methods: Young permanent tooth apical papillae were obtained by the oral surgeon. The cells from the apical papillae were isolated, cultured and analyzed through a flow cytometer. The cells in the experimental group were induced both osteogenic and adipogenic differentiation. The cells were not induced in the control group.Both groups were evaluated by staining and real-time polymerase chain reaction (real-time PCR) to examine the quantity of RNAs in the experimental group. The cells from apical papillae were also cultured with ADM. These cells were also induced both osteogenic and adipogenic differentiation in the experimental group, and not induced in the control group. The measures of staining and real-time PCR were also carried out. Results: The cells from the apical papillae proliferated in a rapid rate. Of which 70.3% in cultures were positive for Stro-1, and 96% positive for CD105 according to flow cytometric analysis. After induction, the RNA level related to osteogenic and adipogenic differentiation expressed higher in the experimental group than those of the control group without induction obviously, such as osteocalcin (OCN)， bone sialoprotein (BSP), liver X-recepter α (LXRα)， lipoprotein lipase（LPL）， peroxisome proliferator activated receptor γ (PPAR-γ)， and scavenger receptor class B type 1（SR-B1）. The cells cultured with ADM also had a fast proliferation, and grew attached to ADM. After induction, the RNA level of OCN and BSP had a higher expression than the control group (P>0.05), and LPL also expressed higher (P<0.05). Conclusion: The study approved that there were a big amount of stem cells in the young permanent tooth apical papilla obtained by oral surgery, which had significant osteogenic potential. The cells still proliferated well when they were cultured with ADM as a kind of collagen skelecton. The results showed that ADM could be performed as a base to support the stem cells to survive the environment, and it also could play a role in osteogenic differentiation of stem cells from apical papilla.

Key words: Dental papilla, Stem cells, Acellular dermis, Cell differentiation