Characteristics of stem cells derived from the periodontal ligament of human deciduous and permanent teeth

Abstract

In many studies, adult stem cells have been found in human periodontal ligament (PDL), but in most cases they were found in the permanent teeth, and seldom in the deciduous teeth. The aim of the present study was to characterize stem cells from the PDL of deciduous teeth (dPDLSCs) and compare them with those from the PDL of permanent teeth (pPDLSCs). First, we investigated the proliferation rates and cell cycles of the stem cells. Stem-cell markers were examined by flow cytometric analysis and reverse transcriptase–polymerase chain reaction (RT-PCR). The results of in vitro differentiation into adipogenic, osteogenic, and chondrogenic lineages were analyzed by histochemical staining and quantitative RT-PCR. The results of in vivo transplantation into immunodeficient mice were analyzed by histological staining, immunohistochemical staining, and quantitative RT-PCR. There were no difference in proliferation rate, cell-cycle distribution, and expression of stem-cell markers such as Oct-4, Nanog, Nestin, Stro-1, CD146, CD105, and CD90 between the stem cells. The potential for adipogenic differentiation was greater in the pPDLSCs than in the dPDLSCs, but that of osteogenic and chondrogenic differentiation was similar in the two cell types. The pPDLSC transplants made more structural cementum/PDL-like tissues than the dPDLSC transplants, in which the expression of cementum/PDL-related genes was also low (CP23, scleraxis, and collagen XII). Together these results suggest that dPDLSCs resemble pPDLSCs with regard to proliferation rate and the presence of stem-cell markers. The dPDLSCs could be a good stem-cell source for use in hard tissues or in cartilage regeneration as well as cementum/PDL complex.