Effect of bone morphogenetic protein-4 overexpression on the biological activity of mouse induced pluripotent stem cells / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study aimed to construct the expression of bone morphogenetic protein-4 (BMP4) lentiviral vector gene and explore its influence on the biological activity of mouse induced pluripotent stem (iPS) cells.</p><p><b>METHODS</b>iPS cell lines stably overexpressing BMP4 were constructed by lentivirus transfection (BMP4-overexpressing group). Cells without transfection served as the blank group, and cells with only vector transfection served as the empty-vector group. Cell proliferation was detected by CCK8, and the expression levels of ameloblastin (AMBN), cytokeratin (CK) 14, dentin sialophospho-protein (DSPP), bone sialoprotein (BSP), and Runx2 mRNA were detected by quantitative polymerase chain reaction. Alkaline phosphatase (ALP) activity was used to detect the degree of cell differentiation.</p><p><b>RESULTS</b>Compared with blank and empty-vector groups, proliferation activity and ALP activity of BMP4-overexpressing group obvious increased (P<0.05), BMP4, AMBN, CK14, DSPP, BSP, Runx2 mRNA expression also increased (P<0.05).</p><p><b>CONCLUSIONS</b>BMP4 can significantly promote the odontogenic differentiation of iPS.</p>

Influence of receptor activity modifying protein 1 overexpression on enhancing effect of calcitonin gene-related peptide on MG-63 cells proliferation / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the influnce of receptor activity modifying protein 1(RAMP-1) overexpression on enhancing effect of calcitonin gene-related peptide on MG-63 cells proliferation.</p><p><b>METHODS</b>Cultured MG-63 osteoblasts in exponential phase of growth were randomly divided into three groups: RAMP-1 overexpression group, empty vector control group and negative control group. RAMP-1 eukaryotic expression vector was constructed and stably transfected into MG-63 cells. Realtime-polymerase chain reaction, Western blotting and immunofluroescence were used respectively to detect the expression of calcitonin receptor-like receptor (CRLR) in the cells and its distribution on cell membrane. The status of proliferation was detected respectively at 0, 24, 48, 72, 96 h by cell counting kit-8 (CCK-8) and cells were collected to analyze their cycle respectively at 0, 8, 16, 24 h by flow cytometry.</p><p><b>RESULTS</b>CRLR protein and mRNA expression levels of MG-63 cells in RAMP-1 overexpression group were significantly higher than the other two groups (P < 0.05). The A value of RAMP-1 overexpression group at 24, 48, 72, 96 h were 0.628 ± 0.175, 0.896 ± 0.592, 1.055 ± 0.004, 1.179 ± 0.618, respectively, which were significantly higher than that of the other two groups (P < 0.05). The difference was most pronounced at 72 h. S-phase fraction of RAMP-1 overexpression group was (1.25 ± 0.13)%, (68.79 ± 0.56)%, (64.49 ± 1.59)%, (57.82 ± 0.75)%, respectively, which were significantly higher than the other two groups (P < 0.05). The difference was most pronounced at 8 h.</p><p><b>CONCLUSIONS</b>RAMP-1 overexpression can promote CRLR distribution on MG-63 cell membrane and enhance CGRP's promotion effect on MG-63 cell proliferation.</p>

Computer simulation of projectile injuries to pig mandibular angle / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the feasibility of computer simulation in maxillofacial firearm injury.</p><p><b>METHODS</b>The three-dimensional finite element models and simulations of 7.62 mm, 5.56 mm standard bullets projectile injuries to pig mandibular angle were established by using MIMICS, ANSA, LS-DYNA and LS-POST software. Based on the simulation results, the bullet hole diameters, energy loss values, energy loss rates, von Mises stress, effective strain, effective strain rate dynamic contours at different time points were used for biomechanical analysis.</p><p><b>RESULTS</b>The damage processe of 7.62 mm, 5.56 mm standard bullets projectile injury to pig mandibular angle were simulated successfully. The injury rate of 7.62 mm standard bullet and injury severity of the mandible were higher than that of 5.56 mm standard bullet.</p><p><b>CONCLUSIONS</b>Computer simulation can simulate maxillofacial firearm injuries effectively and may become an important method for oral and maxillofacial firearm injuries analysis.</p>

Effect of Notch ligand Delta1-RNA interference by lentivirus on proliferation and differentiation of human dental pulp stem cells / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effects of specific RNA interference (RNAi) to Notch ligand Delta1 on proliferation and differentiation of human dental pulp stem cells (DPSC).</p><p><b>METHODS</b>DPSC were infected by lentivirus vectors carrying Delta1-RNAi. DPSC were divided into three groups, DPSC/Delta1-RNAi group, DPSC/wt group and DPSC/vector group as control. Cell counting kit-8 (CCK-8) assay and flow cytometry were used to evaluate the proliferation of DPSC. Expression of proliferating cell nuclear antigen (PCNA) was examined with immunohistochemical staining. All groups were cultured in an odonto-inductive medium and were observed under microscope. The number of mineralization nodules was counted after Alizarin red staining. Alkaline phosphatase (ALP) activity and the expression of dentin sialophosphoprotein (DSPP) were detected by ALP activity assay and Western blotting.</p><p><b>RESULTS</b>Compared with DPSC/wt or DPSC/vector separately, proliferating rate and S-cycle of DPSC/Delta1-RNAi was significantly lower. The S phase and proliferation index (PI) decreased markedly from 22.32 ± 2.35 and 33.68 ± 4.19 (DPSC/Delta1-RNAi) to 5.44 ± 0.91 and 16.00 ± 6.07 (DPSC/wt). The PCNA staining of DPSC/Delta1-RNAi was evidently weaker. DPSC/Delta1-RNAi group had more calcified cell nodules than the other two control groups, and ALP activity and DSPP expression of DPSC/Delta1-RNAi group increased markedly.</p><p><b>CONCLUSIONS</b>Delta1-RNAi induced by the lentivirus vectors may inhibit DPSC proliferation and differentiation. Notch-Delta signal pathway plays an important role in self-renewal and differentiation.</p>

Isolation and identification of huamn dental pulp stem cells / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To isolate and identify human dental pulp stem cells from third molars.</p><p><b>METHODS</b>Dental pulps were dissected and digested by collagenase type I and dispase. The obtained single cell supernatant were harvested and cultured. Characterization of the phenotype of DPSCs was detected by immunohistochemical method and RT-PCR assay. Cell cycle was analyzed by FCM. Differentiation potential of DPSCs was evaluated.</p><p><b>RESULTS</b>Colony-forming efficiency of cells derived from dental pulp tissue was 2 - 15 clones/10(3) cells plated. DPSCs were found to express many different markers, including vimentin, collagen type I, GFAP, nestin and osteocalcin, while they failed to react with MyoD and DSPP. About 64.1% of the cells were in G0/G1 phases, while only 35.8% in proliferation (S + G2 + M). Grown in an adipogenic cocktail medium for three weeks, some DPSCs expressed fat cell markers of PPARgamma and LPL, and formed oil red O-positive lipid clusters in five weeks. After culture with a myogenic-inductive medium, DPSCs were found to express MyoD, desmin and myosin, markers of myocyte. Long-term cultures of DPSCs grown in differentiation inductive medium demonstrated the capacity to form Von Kossa-positive condensed nodules with high levels of calcium.</p><p><b>CONCLUSION</b>Cells isolated from adult human dental pulp are clonogenic, and have multipotent differentiation potential, satisfying the criteria of postnatal somatic stem cell.</p>