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.

Objective To explore risk factors for developing neurogenic heterotopic ossification (NHO) after traumatic brain injury (TBI).Methods Thirty-three patients suffering from TBI no more than 6 months and admitted to Guangdong Work Injury Rehabilitation Hospital between December 2015 and December 2016 were selected.Those with and without NHO was assigned to an NHO group (n =12) and a control group (n =21) respectively.The two groups were compared in terms of the duration of coma and mechanical ventilation,the time to start rehabilitation and the occurrence of infection,pressure ulceration,deep vein thrombosis (DVT) or inflammation.Muscle tension,white blood cell (WBC) count,erythrocyte sedimentation rate (ESR),high sensitivity creactive protein (hsCRP) and alkaline phosphatase (ALP) were also measured.Independent sample T tests,chi-squared tests and binary logistic regression were used to compare the two groups seeking to isolate risk factors for NHO which might be predictive.Results Significantly prolonged coma and/or mechanical ventilation were observed in NHO group compared to the control group.Significant differences were also found in the average WBC,ESR,hsCRP and ALP levels,as well as in the occurrence of infection,DVT and inflammatory symptoms between the two groups.The incidences of infection,DVT and inflammatory reaction were higher in the NHO group,as were the levels of leukocyte,ESR,hsCRP and ALP.Those differences between the groups were statistically (and of course clinically) significant.The duration of coma and mechanical ventilation,infection,DVT,inflammation,and elevated levels of leukocytes,ESR or ALP can all usefully be considered risk factors for NHO,with infection,DVT and inflammation of the highest importance.Conclusion Duration of coma and utilization of mechanical ventilation,infection,DVT,inflammation,as well as an increase of leukocytes,ESR or ALP should be considered as risk factors for NHO after TBI.