Abstract: Abstract: Objective To detect the expression pattern of embryonic stem cell (ESC) markers in human periodontal ligament stem cells (PDLCs). Methods PDLCs were isolated from human periodontal ligament tissue, and characterized by multipotent differentiation and cell surface analysis. Immunocytochemistry and RT-PCR were performed to detect the expression of ESC markers (Oct4、Nanog、Sox2、SSEA-4、TRA-1-60、TRA-1-81) in PDLCs. Results PDLCs exhibited typical fibroblast-like morphology, and could differentiate into osteoblasts and chondroblasts. PDLCs homogenously expressed mesenchymal markers of CD44, CD90 and CD105, but heterogenously expressed CD146 and Stro-1. Part of ESC markers was detected in PDLCs. Oct4, Nanog, SSEA-4 and TRA-1-60 were positive in PDLCs while Sox2 and TRA-1-81 were negative. Semi RT-PCR demonstrated similar expression of Oct4 and Nanog in PDLCs of Passage 3 and 8. However, sox2 were negative at the mRNA level. Conclusion Besides mesenchymal stem cells markers, PDLCs could also express parts of ESC markers, which is of certain application value to the identification and purification of periodontal ligament cells.