BACKGROUND:Stable and efficient labeling of dental pulp stem cel s in vitro is most important in tracer technique, which is also the basis of tooth regeneration in vivo.
OBJECTIVE:To determine the optimal condition and method for transfection of stem cel s derived from rat dental pulp with green fluorescent protein infection by lentiviral vector and to determine whether green fluorescent protein-labeled dental pulp stem cel s maintain their stem cel properties.
METHODS:Rat dental pulp stem cel s were obtained by modified enzyme digestion method, to identify the immune phenotype and differentiation potential. Dental pulp stem cel s were infected with green fluorescent protein by lentiviral vector for 24 and 48 hours at different multiplicity of infection (MOI) (5, 10, 25, 50 and 100). The infection efficiency and fluorescence intensity were analyzed by inverted fluorescent microscopy. The clonal and proliferation ability, cel cycle and the mineralization potential were compared before and after transfection. Based on those mentioned above, we could evaluate the influence of infection on their biological characteristics.
RESULTS AND CONCLUSION:Flow cytometry results showed that rat dental pulp stem cel s expressed STRO-1 and CD146 but not CD34 or CD45. The dental pulp stem cel s could differentiate into osteoblasts and
adipocytes when cultured in specific medium for each lineage differentiation. The highest efficiency of infection and strongest fluorescence expression appeared at 48 hours of infection and MOI 50. There were no significant differences in growth ability, cel colony formation rate and cel cycle before and after transfection (P>0.05). And the alkaline phosphatase expressed positively. Infection for 48 hours at MOI 50 is optimal for transfecting dental pulp stem cel s with green fluorescent protein by a lentiviral vector, thereby providing reliable tracer method for the study of rat dental pulp stem cel s in vivo.

cryopreservation periodontal tissue. METHODS:Periodontal tissue was scraped from healthy human teeth and divided them into three equal parts:fresh group, harvesting periodontal ligament stem cel s from fresh tissue;5%dimethyl sulfoxide group, 5%dimethyl sulfoxide added into the cryopreservation system;10%dimethyl sulfoxide group, 10%dimethyl sulfoxide added into the cryopreservation system. One month later, periodontal ligament stem cel s were extracted from the cryopreserved periodontal ligament from the latter two groups. RESULTS AND CONCLUSION:In the time that cel s swam out of tissue mass and cel harvest amount, the 5%dimethyl sulfoxide group was inferior to the fresh group but better than the 10%dimethyl sulfoxide group (P<0.05). No differences were found among the three groups in the fol owing aspects (P>0.05):colony formation rate of passage 1 periodontal ligament stem cel s, cel survival rate, proliferation ability of passage 3 periodontal ligament stem cel s, cel growth curve and surface marker expression of periodontal ligament stem cel s. The results suggest that the 5%dimethyl sulfoxide added cryopreserved system for periodontal ligament tissue cannot only shorten the time of periodontal ligament stem cel s amplification in vitro, ensure cel harvest and maintain basic cel ular biological characteristics, but also reduce the total amount of the dimethyl sulfoxide and the direct damage to the cel s caused by repeatedly frozen cel s, thereby providing a more secure guarantee for the future implementation of clinical transplantation therapy. So, the 5%dimethyl sulfoxide added cryopreserved system may be the new selection for donor tissue storage.

Objective:To investigate the effect of head model in improving the photographic ability of interns during the photographic training of oral facial image in pediatric dentistry.Methods:A total of 60 interns of stomatology school affiliated to Xinjiang Medical University were randomly divided into head model training group, mutual training group and clinical probation group for photographic training. After the training, the interns in the three groups were evaluated for the photographic time, the level of photos, etc., by the training test and satisfaction level of volunteers. Besides, the head model training group was conducted by questionnaire survey. One-way analysis of variance and least significant difference analysis were used to analyze the data between groups by SPSS 17.0 software.Results:There was no statistical difference between the head model training group and the mutual training group in photographic time and level of photos, while both of them were much better in the head model training group and mutual training group than in the clinical probation group ( P<0.05). There was no statistical difference between the head model training group and the mutual training group in the satisfaction level, while that was lower in the head model training group than in the clinical probation group ( P<0.05). According to the questionnaire survey, most interns in the head model training group acknowledged its effects. Conclusion:The use of head model can help improve the oral photographic ability, and promote the teaching effect and efficiency in photographic training.