Study of ALU methylation levels in various passages of human dental pulp stem cells

Abstract

Human dental pulp stem cells (DPSCs) which can be isolated from pulpal tissue of tooth are being recognized as an alternative source of stem cells for cell-based therapies and tissue engineering. The replicative senescence which results in the alteration of regeneration and differentiation potential is an obstacle encountered during DPSCs culture in vitro. Although both genetic and epigenetic mechanism was found participating in the aging processes, the study in epigenetic mechanisms that involved with these biological processes of DPSCs is still very limited. Methylation level of Alu, an epigenetic alteration, was reported to be associated with human aging. In this study, the methylation level of Alu in different passages of DPSCs was studied by combined bisulfite restriction analysis. Moreover, the morphology and proliferation ability of human DPSCs were observed in every passages. We found that DPSCs in late passage showed replicative senescence, morphological change and had significant lower Alu methylation level than early passage. Our results suggest that Alu methylation level may involve in replicative senescence of DPSCs. Further study should be performed to clarify the mechanism controlling senescence of DPSCs in order to properly manipulation of DPSCs in therapeutic use.