[Immortalization of human dental pulp stem cells caused by transferring hTERT gene].

PURPOSE: To establish an immortalized human dental pulp stem cell line used for basic and clinical research of oral science. METHODS: Human telomerase reverse transcriptase (hTERT) cDNA was transferred into human dental pulp stem cells (hDPSCs) by lentivirus. The resultant stable clones reproduced successively and the expression of hTERT was identified. RESULTS: The hTERT gene was transferred into human dental pulp stem cells successfully. The transformed cells expressed telomerase activity and divided vigorously. p35 had been obtained so far. CONCLUSIONS: The hDPSCs can be immortalized by transferring exogenous hTERT gene to constitute telomerase activity.

The impact of various time intervals on the supragingival plaque dynamic core microbiome.

OBJECTIVE: The aim of this study was to examine the influence of various time intervals on the composition of the supragingival plaque microbiome, especially the dynamic core microbiome, and to find a suitable observation interval for further studies on oral microbiota. METHODS AND MATERIALS: Eight qualified volunteers whose respective age ranges from 25 to 28 years participated in the present study. The supragingival plaque was collected from the buccogingival surface of the maxillary first molar at eight time slots with different intervals (day 0, 1 day, 3 days, 1 week, 2 weeks, 3 weeks, 1 month, and 3 months). Bioinformatic analyses was performed based on 16S rDNA pyrosequencing (454 sequencing platform) targeting at the hypervariable V4-V5 region, in order to assess the diversity and variation of the supragingival plaque microbiome. RESULTS: A total of 359,565 qualified reads for 64 samples were generated for subsequent analyses, which represents 8,452 operational taxonomic units identified at 3% dissimilarity. The dynamic core microbiome detected in the current study included five phyla, 12 genera and 13 species. At the genus level, the relative abundance of bacterial communities under the "1 day," "1 month," and "3 months" intervals was clustered into sub-category. At the species level, the number of overlapping species remained stable between the "1 month" and "3 months" intervals, whereas the number of dynamic core species became stable within only 1 week. CONCLUSIONS: This study emphasized the impact of different time intervals (days, weeks and months) on the composition, commonality and diversity of the supragingival microbiome. The analyses found that for various types of studies, the time interval of a month is more suitable for observing the general composition of the supragingival microbiome, and that a week is better for observing the dynamic core microbiome.

[Exploring the stem cell surface markers expressed in human dental pulp stem cells].

PURPOSE: To explore the stem cell surface markers expressed in human dental pulp stem cells which were selected and isolated by magnetic beads. METHODS: Human dental pulp cells (hDPCs) were separated and cultured from dental pulp of healthy third molars for orthodontic purpose. HDPSCs were isolated from cultured hDPCs by magnetic-activated cell sorting's (MACS) indirect magnetic cell labeling and positive selection strategy with antibody STRO-1 in the 2nd generation. Then the stem cell surface markers (CD73, CD90, CD105, CD166 and STRO-1) were respectively detected in 3, 4, 5, 6, 7 and 8 generation of dental pulp stem cells. HDPSCs were induced to differentiation by adipogenic medium and osteogenic medium in the 3rd generation. Adipogenic differentiation was assessed by oil red O staining in day 21, and osteogenic differentiation was assessed by alizarin red staining in day 21. RESULTS: HDPSCs could differentiate into adipocyte and osteoblasts. Oil red O staining and alizarin red staining were positively expressed after induction of HDPSCs. STRO-1's expression was decreased with the increase of generation. The expressions of CD73, CD90, CD105 and CD166 were relatively stable. CONCLUSIONS: The expression of STRO-1 is declined with the increase of generation, and the expressions of CD73, CD90, CD105 and CD166 are relatively stable with the changes of generation. Supported by National Natural Science Foundation of China (81070826/81371143) and Shanghai Rising-Star Program (12QH1401400).