BACKGROUND:Human periodontal ligament stem cels are a kind of mesenchymal stem cels that have self-renewal and multidifferentiation potential. Previous studies have showed that human periodontal ligament stem cels can differentiate into osteoblast-like cels or adipocyte-like cels under appropriate induction. Yet few studies have focused on the expression level of parathyroid hormone 1 receptor which wil affect the osteogenic potential of Human periodontal ligament stem cels. OBJECTIVE:To examine the expression level of parathyroid hormone 1 receptor between human periodontal ligament stem cels and human periodontal ligament cels and to discuss the role of parathyroid hormone 1 receptor in osteogenic differentiation. METHODS:By using magnetic-bead cel sorting, we separated and identified the human periodontal ligament stem cels and human periodontal ligament cels. We examined and compared the mRNA expression level of parathyroid hormone 1 receptor in human periodontal ligament stem cels and human periodontal ligament cels by Real-Time PCR. Osteoblastic differentiation was examined throughin vitro matrix mineralization by alizarin red staining and alkaline phosphatase assay. RESULTS AND CONCLUSION: Positive immunomagetic sorted cels were positive for STRO-1, CD146, Vimentin, indicating that they were periodontal ligament stem cels. Parathyroid hormone 1 receptor was expressed in human periodontal ligament stem cels and mainly located in cel membrane and cytoplasm which were similar to human periodontal ligament cels and MG63 cels. The expression of parathyroid hormone 1 receptor in human periodontal ligament stem cels was 3.7 times higher than that in human periodontal ligament cels, which was similar to that in MG63 cels. After osteogenic induction, human periodontal ligament stem cels showed a higher expression of parathyroid hormone 1 receptor and osteoblast-related genes as wel as the activity of osteoblast alkaline phosphatase and mineralization compared to human periodontal ligament cels. Our data showed that parathyroid hormone 1 receptor was higher in human periodontal ligament stem cels than human periodontal ligament cels and the expression was related with osteogenic differentiation, suggesting that human periodontal ligament stem cels display a higher potency of osteogenic differentiation and act as seed cels with a vast application prospect in oral tissue engineering.