Human teeth have been identified as a new source of postnatal stem cells that have the capacities of selfrenewal
and multilineage differentiation. In this study we compared the characteristics of stem cells obtained from
the periodontal ligament of supernumerary teeth (sPDLSCs) with those of bone-marrow-derived mesenchymal stem
cells (BMMSCs), with the aim of extending the sources of stem cells. We performed a colony forming unit-fibroblast
(CFU-F) assay to evaluate the self-renewal ability of the cells. Reverse transcription-polymerase chain reaction (RTPCR)
and flow cytometry analyses were used to detect the expressions of various stem-cell markers: Oct-4, Nanog,
Nestin, Stro-1, CD146, CD105, CD29, CD44, CD90 and CD31. The abilities of adipogenic and osteogenic differentiation
were monitored by histochemical staining and quantitative RT-PCR. The colony-forming efficiency was
slightly higher for sPDLSCs than for BMMSCs (6.0% vs. 5.1%, respectively). The two stem cell populations
expressed similar stem-cell markers except Nestin, Stro-1, and CD146. The sPDLSCs could differentiate to adipogenic
lineage; however, the up-regulation of peroxisome-proliferator-activated receptor γ2 (PPARγ2) and lipoprotein
lipase (LPL) gene expressions was less than for the BMMSCs. Osteogenic differentiation of the sPDLSCs was
confirmed by up-regulation of alkaline phosphatase (ALP) and bone sialoprotein (BSP) gene expressions, but elevation
of ALP gene expression was observed earlier than for the BMMSCs. We have shown that sPDLSCs exhibit
stem-cell properties such as self-renewal ability, expression of stem-cell markers, and differentiation into adipogenic
and osteogenic lineages. This cell type could represent a good stem-cell candidate for use in regenerative medicine.