A study of root forming in immatured teeth. -Effect of enamel matrix protein on cementoblasts.-

为了设计可预测的地方病和未成熟牙齿的再植疗法，了解细胞在局部环境中的反应性是很重要的。本研究旨在探讨釉质基质蛋白(EMP)对成牙本质细胞的影响。方法：采用骨钙素(OC)启动子SV40转基因小鼠获得成牙骨质细胞。通过细胞计数、Northern印迹分析、von Kossa染色和从免疫缺陷(SCID)小鼠取材的种植体制备组织学标本，评估成牙骨质细胞在6天内的增殖情况；以及3)生物矿化的生物矿化。结果：EMP可促进成牙本质细胞增殖。EMP下调成牙骨质细胞骨钙素转录，上调骨桥蛋白基因表达。在体外，EMP减少了成牙骨质细胞介导的生物矿化。相反，从SCID小鼠中提取的植入物中发现了矿化，其中细胞被电磁脉冲预处理。结论：电磁脉冲可影响成牙本质细胞的活性。

In order to design to predictable enzootics and replantation therapies in immature teeth, it is important to understand the responsiveness of cells within the local environment. The aim of this study was to determine the effect of enamel matrix protein (EMP) on cementoblasts. Methods : Osteocalcin (OC) promoter SV40 transgenic mice were used to obtain cementoblasts. Cementoblasts were exposed enamel matrix protein were evaluated for changes in : 1)proliferation over a 6-day period by cell counting ; 2)gene expression using Northern blot analysis ; and 3)biomineralization by von Kossa stain, in vitro and by preparing histological samples from implants retrieved from immunodeficient (SCID) mice, where cementoblasts were treated with enamel matrix protein prior to implantation. Results : EMP promoted proliferation of cementoblasts. EMP down-regulated osteocalcin transcripts in cementoblasts and up-regulated osteopontin gene expression. In vitro, EMP decreased cementoblasts -mediated biomineralization. In contrast, mineralization was noted in implants retrieved from SCID mice, where cells were pretreated with EMP. Conclusion : these results indicate that EMP can influence activities of cementoblasts.