| Human have only one opportunity to replace their teeth in their lifetime, tooth damage will no doubt have a great impact on people’s daily lives. Because of the importance of reengineering teeth and the possibility of realizing, tooth regeneration has become a hotspot of tissue engineering. Dental pulp stem cells (DPSC) have been one kind of seed cells in tissue engineering in recent years. Natural DPSC can repaire tooth tissue damage, but lack the ability of inducing epithelial differentiation and regeneration of the tooth. This thesis aims to use the technology of lentivirus-mediated overexpression of key genes in the process of tooth development, so as to explore the impact of these genes on the differentiation ability of DPSC. In our study, we separated the dental pulp stem cells from the adult third molar, and subcultured them. Then we used lentiviral vectors carrying the MSX1, BMP4, PAX9target gene to produce a large number of lentivirous and concentrated it to a higher titer, and infected dental pulp stem cells respectively, in order to achieve the over-expression of target genes. We respectively combined the over-expressed dental pulp stem cells with stent, and transplanted them into the back of immunodeficiency mouse, regained the transplants after8weeks and observed their structure, In the experiments, we found that the transplants of BMP4-overexpressed DPSC and MSX1-overexpressed DPSC showed tumor-like structure, which demonstrated that, BMP4, MSX1over-expression may change the proliferation characteristic of DPSC and transformed them into tumor cells. The transplants of PAX9-overexpressed DPSC, nomal DPSC and no-load virus infected DPSC showed dentin matrix-like structure and expressed dentin sialoprotein (DSP) in extracellular matrix, and PAX9-overexpressed DPSC expressed more DSP, which demonstrated that the over-expression of PAX9can improve the tooth differentiation potential and the ability of tooth induction in DPSC. |
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