老年大鼠切牙造牙本质细胞的超微结构变化

应用透射电镜研究了老年大鼠切牙造牙本质细胞的超微结构变化。该细胞核出现凹陷和切迹，常染色质减少，异染色质增加。胞浆内粗面内质网扩张，变短，线粒体水肿，嵴断裂，最后空泡化，高尔基复合体由复杂到简单，最后消失。     

Knockdown of NRAGE induces odontogenic differentiation by activating NF-κB signaling in mouse odontoblast-like cells

Purpose: Neurotrophin receptor-interacting MAGE homologue (Nrage) plays an important role in bone development and the metabolism of normal skeletal structures. Our previous study showed that Nrage inhibited the odontogenic differentiation of mouse dental pulp cells. However, the potential roles and mechanism of Nrage in regulating odontogenic differentiation are unknown. The aim of this study was to investigate the molecular mechanism of Nrage in odontogenic differentiation of mouse odontoblast-like cells.

Materials and methods: Endogenous expression of Nrage was stably downregulated by lentivirus-mediated shRNA. Mineralized nodules formation was detected by alizarin red S staining. Dmp-1, Dspp, and ALP mRNA and protein levels were detected by qRT-PCR and western blotting, respectively. In addition, ALPase activity was detected. Confocal microscopy and co-immunoprecipitation (co-IP) were used to analyze the interactions between NRAGE and NF-κB signaling molecules. An IKK inhibitor was also used in the study.

Results: NRAGE expression in odontoblasts was downregulated during mouse first maxillary molar development. Moreover, NRAGE expression was downregulated during odontogenic differentiation of odontoblast-like cells. NRAGE knockdown significantly upregulated DMP1 and DSP expression, increased ALPase activity, and promoted mineralized nodule formation. In addition, NRAGE knockdown increased the translocation of NF-κB1 to the nucleus and phosphorylation levels of p65. Co-IP results showed that NRAGE bound to IKKβ. Most importantly, the promoting effect of Nrage knockdown on odontoblastic differentiation was reduced after treatment with an IKK inhibitor.

Conclusions: Our data confirmed that NRAGE is an important regulator of odontogenic differentiation of odontoblasts by inhibiting the NF-κB signaling pathway through binding to IKKβ.

Abbreviations: Nrage: neurotrophin receptor-interacting MAGE homologue; DSP: dentin sialophospho protein; DMP-1: dentin matrix protein-1; BMP: bone morphogenetic protein; Wnt: wingless; NF-κB: nuclear factor of activated B cells; DAPI: 4′,6-diamidino-2-phenylindole; KO: knockout; DPCs: dental pulp cells; AA: ascorbic acid; β-Gly: β-glycerophosphate; Dex: dexamethasone; co-IP: co-immunoprecipitation; IκB: inhibitor of NF-κB; IKK: IκB kinase     

人类β-防御素在正常、深龋和炎症牙髓中的表达

目的:研究人类β-防御素(human beta-defensins,HBD)在正常、深龋和炎症牙髓中的表达及其意义。方法:采用免疫组化SP法分别对正常、深龋及炎症牙髓中β-防御素HBD-1、HBD-4的表达进行组织学定位,并通过Image pro-plus 5.1图像分析软件对HBD-1/HBD-4染色进行平均光密度值的测定。所得数据用SPSS 13.0统计软件进行相应的统计学分析。结果:在人牙髓中,β-防御素主要表达在成牙本质细胞的细胞核及细胞突起中。HBD-1在3组内表达无显著差异(P>0.05);HBD-4在深龋和牙髓炎组中的表达与正常组相比均显著增强(P<0.05),且炎症组亦强于深龋组,差异有统计学意义(P<0.05)。结论:HBD-1参与牙髓天然免疫系统;HBD-4参与龋病发展过程中牙髓组织的免疫防御反应。     

Dentin Phosphophoryn-Derived Peptide Promotes Odontoblast Differentiation In Vitro and Dentin Regeneration In Vivo

The purpose of the present study was to investigate the effect of a peptide (i.e., SESDNNSSSRGDASYNSDES) derived from dentin phosphophoryn (DPP) with arginine-glycine-aspartic acid (RGD) motifs on odontoblast differentiation in vitro and to compare it with calcium hydroxide—a material used conventionally for vital pulp therapy—in terms of reparative dentin formation and pulp inflammation in vivo. Alkaline phosphatase activity assay and alizarin red S staining were performed to evaluate odontoblast-differentiation in cell culturing experiments. To observe the reparative dentin formation and pulp inflammation animal experiment was performed and examined by histological methods. The difference between the experimental group and the control group was analyzed statistically using a one-way ANOVA test. The results revealed that the DPP-derived RGD-containing peptide triggered odontoblast differentiation and mineralization in vitro. In rats undergoing direct pulp capping, the DPP-derived RGD-containing peptide was found to induce intensively formed reparative dentin with high compactness at week 4. On histological and morphometrical examinations, a smaller degree of pulpitis was observed in the specimens treated with the peptide than in those treated with calcium hydroxide. This study suggests that the DPP-derived RGD-containing peptide is a biocompatible, biodegradable and bioactive material for dentin regeneration.     

修复性牙本质形成的机理与调控

修复性牙本质的形成是牙体组织重要的保护性防御行为,在牙体组织遭受龋损、外伤、严重磨耗等损伤时,对于保护牙髓的活性和功能具有重要意义。修复性牙本质形成的机制较为复杂,有多种细胞参与,并受各类因子调控。本文就修复性牙本质的形成机制及其促进因素作一综述。     

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目的研究代谢性谷氨酸受体第5亚型（mGluR5）在牙髓各部位中的表达及分布。方法收集2009年7月至2010年1月山东大学口腔医院口腔颌面外科因正畸或其他治疗需要而拔除的健康前磨牙或第三磨牙5例,制成一系列石蜡切片,利用免疫组化方法检测牙髓各部位mGluR5的表达及分布情况,利用图像分析系统对其表达强度进行半定量分析,探讨mGluR5在牙髓中的作用和意义。结果正常牙髓从冠部、颈部到根部牙髓成牙本质细胞中mGluR5表达均呈阳性,且由冠部、颈部到根部mGluR5表达强度依次降低。结论mGluR5在牙髓疼痛传递过程中可能具有一定的作用。     

组织工程化牙本质种子细胞的研究进展

成牙本质细胞是牙齿发育的重要细胞,寻找形成成牙本质细胞的种子细胞,获得稳定可靠的细胞来源是组织工程化牙本质研制的先决条件.牙胚、牙乳头、牙髓,甚至脱落的乳牙牙髓里都存在形成牙齿的前体细胞.本文就近年来组织工程化牙本质种子细胞的研究现状进行了综述.