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In the orthodontics process, intervention and sliding of an orthodontic bracket during the orthodontic process can arise large response of the labio-cheek soft tissue. Soft tissue damage and ulcers frequently happen at the early stage of orthodontic treatment. In the field of orthodontic medicine, qualitative analysis is always carried out through statistics of clinical cases, while quantitative explanation of bio-mechanical mechanism is lacking. For this purpose, finite element analysis of a three-dimensional labio-cheek-bracket-tooth model is conducted to quantify the bracket-induced mechanical response of the labio-cheek soft tissue, which involves complex coupling of contact nonlinearity, material nonlinearity and geometric nonlinearity. Firstly, based on the biological composition characteristics of labio-cheek, a second-order Ogden model is optimally selected to describe the adipose-like material of the labio-cheek soft tissue. Secondly, according to the characteristics of oral activity, a two-stage simulation model of bracket intervention and orthogonal sliding is established, and the key contact parameters are optimally set. Finally, the two-level analysis method of overall model and submodel is used to achieve efficient solution of high-precision strains in submodels based on the displacement boundary obtained from the overall model calculation. Calculation results with four typical tooth morphologies during orthodontic treatment show that: ① the maximum strain of soft tissue is distributed along the sharp edges of the bracket, consistent with the clinically observed profile of soft tissue deformation; ② the maximum strain of soft tissue is reduced as the teeth align, consistent with the clinical manifestation of common damage and ulcers at the beginning of orthodontic treatment and reduced patient discomfort at the end of treatment. The method in this paper can provide reference for relevant quantitative analysis studies in the field of orthodontic medical treatment at home and abroad, and further benefit to the product development analysis of new orthodontic devices.
Subject(s)
Humans , Periodontal Ligament/physiology , Orthodontic Wires , Cheek , Ulcer , Tooth , Finite Element AnalysisABSTRACT
Objective To compare the reprogramming effects and biological characteristics of two types of human odontogen-ic induced pluripotent stem cells(iPSCs).Methods Human dental pulp stem cells(DPSCs)and stem cells from apical papilla (SCAP)were isolated and primarily cultured.The Sendai reprogramming system was utilized to induce DPSCs and SCAP into iP-SCs.The morphology,reprogramming efficiency,reprogramming and time were compared between human DPSCs-iPSCs and SCAP-iPSCs.The SeV and exogenous transcriptional gene expression were detected by RT-PCR.Results Human DPSCs and SCAP were reprogrammed as iPSCs with classical ES-like clonal morphology.The reprogramming efficiencies were(0.68 ± 0.02)% and(0.7 ± 0.01)% respectively,the difference was not statistically significant(P>0.05).The reprogramming time was(26.0 ± 2.1)d and (27.0 ± 1.4)d respectively,the difference was not statistically significant(P>0.05).The RT-PCR results showed that no expres-sion of exogenous virus or transcriptional gene sequence in both iPSCs.Conclusion Human DPSCs and SCAP can be reprogrammed as virus-free and transgene-free iPSCs,which are the ideal sources of iPSCs.
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Objective To comparatively study the features of two reprogramming systems of induced pluripotent stem cells (iPSCs)from human dental origin.Methods Two kinds of reprogramming system,i.e.STEMCCA lentivirus /feed layer and Sen-dai virus /matrigel were used to induce human stem cells from apical papilla(SCAP)into iPSCs,respectively.The induction efficien-cies,workload of generating iPSCs,aneuploidy karyotype ratio,complexities of eliminating exogenous transcription factors and spe-cific markers expression were compared between these two systems.Results The STEMCCA reprogramming system required to prepare the feeder cell MEF.The reprogramming efficiency was 0.1%.Transcription gene-free iPSCs cells were obtained by the Cre-loxp enzyme digestion technique at the later stage.Sendai virus reprogramming system was feeder-free and the preparation of matrigel was quite simple with unified standard.The reprogramming efficiency was 0.7%,which was much higher than that of STEMCCA system(P <0.05).The exogenous virus and transgenes could be gradually eliminated after several passages of natural subclone.Conclusion The Sendai virus/matrigle reprogramming system is much more applicable for the induction of iPSCs from dental origin than the STEMCCA system.
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Objective To compare the growth characteristics,proliferation and osteo/odontogenic differentiation capability of stem cells from human dental pulp (dental pulp stem cells,DPSCs) and apical papilla (stem cells from apical papilla,SCAP) in vitro.Methods Human dental pulp and apical papilla tissues were separated from impacted third molars of young healthy donors at the age of root development and digested by collagenase type Ⅰ and dispase type Ⅱ to derive primitive DPSCs and SCAP.Cells were then induced for osteo/odontongenic differentiation by medium containing β-glycerophosphate,dexamethasone and KH2PO4.Flow cytometry was utilized to test the expression of specific markers of stem cells,including CD24,CD34,CD45,CD90,CD105,CD146,STRO-1 and OCT-4.AR-S was used to display the mineralization structure and RT-PCR was applied to analyze the expression of bone sialoprotein (BSP),osteocalcin (OCN) and dentine sialophosphoprotein (DSPP).Results Both DPSCs and SCAP were positive for CD90,CD105,CD146,STRO-1 and OCT-4,in percentages varying according to cell type,without expression of CD34 or CD45.Only SCAP expressed CD24 positively.Both cells formed organized mineralization structure after 2 weeks of induction in time-dependent manner,with more mineralization by SCAP and expressed differentiation markers,including BSP,OCN and DSPP.Conclusion Human DPSCs and SCAP possess the characteristics of MSCs and could be differentiated into odontonblast-like cells in vitro.Both cells are approachable stem cell sources for dental tissue engineering.
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Objective To comparatively study the characteristics of 3 kinds of culture substrates of human odontogenic induced pluripotent stem cells(iPSCs).Methods The human odontogenic iPSCs were cultured by 3 kinds of substrates:mouse embryonic fibroblasts(MEF),matrigel and recombinant human vitronectin(VTN-N).The iPSCs growth situation was compared among three groups.Results The preparation time of these 3 kinds of substrates was 14,3,1 hlespectively,and,the difference was statistically significant (P＜0.05).The iPSCs reprogramming time was (30± 1.6),(26 ± 2.1),(27 ± 1.4) d,lespectively,wht that in the MEF group significantly higer than in other two groups (P＜0.05).The reprogramming efficiencies were 0.3 ％ ± 0.03 ％,0.56 ％ ± 0.08 ％,0.7 ％ ± 0.02 ％ respectively (P＜ 0.05).Three kinds of substrate could better support iPSCs growth and make them to maintain un-differentiation status.Conclusion with no heterologous animal components,and the adrantaga of simple pleparation,oonfrollable standard and shorter gramming time is easy to prepare,the standard is controllable and the reprogramming time is shorter,which is an ideal substrate for supporting iPSCs growth.
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<p><b>OBJECTIVE</b>To compare characterization of microRNAs (miRNAs) expression profiles of induced pluripotent stem cells (iPSCs) reprogrammed from human dental pulp stem cells (DPSCs) and stem cells from apical papilla (SCAP) and screen-specific microRNA.</p><p><b>METHODS</b>Human DPSCs and SCAP were reprogrammed into iPSCs using a Sendai virus vector. Total RNA of human DPSCs-iPSCs and SCAP-iPSCs were extracted. miRNAs were labeled and hybridized. Slides were scanned, and images were imported into GenePix Pro 6.0 for grid alignment and data extraction. Significant differentially expressed miRNAs between the two groups were identified using fold change and P-value and were analyzed.</p><p><b>RESULTS</b>Both human DPSCs and SCAP were successfully reprogrammed into iPSCs. Among miRNA genes analyzed by miRNA microarray, 68 were differentially expressed by more than 10-fold in DPSCs-iPSCs; 37 of these genes were up-regulated, and 31 were down-regulated. In SCAP-iPSCs, 107 genes were differentially expressed by more than 10-fold; 68 were up-regulated, and 39 were down-regulated. In both cells, only miR-302e was up-regulated, whereas 9 miRNAs were down-regulated: miR-29b-3p, miR-181b-5p, miR-4328, miR-22-5p, miR-145-5p, miR-4324, let-7b-5p, miR-181a-5p, and miR-27b-3p.</p><p><b>CONCLUSIONS</b>Multiple miRNAs participated in reprogramming of human DPSCs and SCAP into iPSCs. Most miRNAs are related to cell cycle, transforming growth factor-β signaling pathways and epithelial-mesenchymal transition.</p>
Subject(s)
Humans , Cell Cycle , Cell Division , Dental Pulp , Down-Regulation , Electrodes , Epithelial Cells , Induced Pluripotent Stem Cells , MicroRNAs , Taste Buds , Up-RegulationABSTRACT
Aim To develop a simple and rapid method to monitor insulin receptor kinase activity and provide a novel cell-based model for screening anti-diabetes drugs.Methods CHO cells were co-transfected by plasmids which respectively contained insulin receptor gene,STAT5b gene and luciferase gene driven by STAT5 response elements.The expression of exogenous gene in transfected cells was examined by RT-PCR.The transfected cells were treated by insulin,and then the concentration and time-dependent response of luciferase expression to insulin induction was examined.Moreover,the specificity was identified by AG1024 treatment and PTP1B gene transfection.Results Expressions of insulin receptor and STAT5b were detected in the transfected CHO cells.The expression of luciferase in transfected cells was induced by insulin in concentration and time-dependent way.The maximal induction fold was 6.25.Moreover,the inducible expression of luciferase by insulin could be specifically blocked by tyrphostin AG1024,an inhibitor of insulin receptor kinase,or co-transfected PTP1B gene.Conclusions The insulin receptor kinase activity can be detected by expression of reporter gene with high sensitivity and specificity in this cell model,and with potential value in high throughput screening for insulin receptor activators and sensitizers.