Pathways and fate of epithelial root sheath cells during cementogenesis in rat incisors

众所周知，上皮根鞘在根本质的形成和牙周组织的发展中起着重要的作用。提出了上皮根鞘细胞命运的两种可能，一种是被细胞凋亡消灭的途径，另一种是通过上皮-间质转化向成水泥细胞转化的途径。据报道，上皮细胞向间充质细胞的表型转化发生在发育中的穆勒管和腭正中缝合线的上皮细胞中，在一个致病病例中，癌细胞向侵袭性转移细胞的转化也得到了证实。胶凝母细胞的起源仍有争议。成熟的骨水泥母细胞产生与成骨细胞相同的基质蛋白，如I型胶原蛋白、骨钙素和骨桥蛋白。这些特征提示成水泥细胞是定位独特的成骨细胞。另一方面，形态学数据和一些牙髓牙骨质母细胞的表达，如karatin、E-cadherin和amelin/ ameloblasttion / sheathin等，支持了根上皮来源细胞在牙骨质形成过程中也存在的假设。这些发现支持上皮根鞘细胞向成胶细胞分化的上皮-间质转化假说。然而，到目前为止，上皮根鞘细胞的时空行为及其机制尚未阐明。免疫组化结果表明，大鼠门牙根牙本质上皮细胞向成骨水泥细胞连续表达某种热休克蛋白，并在成骨水泥细胞中表达某种水通道蛋白和S100蛋白。这些蛋白在骨水泥形成过程中的表达模式说明了骨水泥母细胞的复杂起源和上皮根鞘细胞的命运。这些结果提示牙源性上皮的间充质转变以及这些蛋白在骨水泥形成过程中的重要性。少

It is well known that the epithelial root sheath is greatly involved in the root dentin formation and the development of periodontium. Two possibilities on the fate of epithelial root sheath cells are proposed, the pathway to be extinguished by the apoptosis, and the pathway to transform into cementblasts by epithelio-mesenchymal transformation. Phenotypic transformation from the epithelial cell into the mesenchymal cell is reported in developing Muellerian duct and the epithelial cells in the median palatine suture, and recognized in the transformation from cancer cells into invasive metastatic cells in a pathogenic case.The origin of cementblastic cells remains controversial. Mature cementblasts produce matrix proteins common to osteoblasts, such as Type I collagen, osteocalcin, and osteopontin. These features led to the suggestion that the cementblasts are uniquely positioned osteoblasts. On the other hand, morphological data and the expression in some cementblasts of dental epithel … More ium markers, such as karatin, E-cadherin and amelin/ameloblastion/sheathlin, support the hypothesis that root epithelium-derived cells also persist during cementum formation. These findings support the epithelial-mesenchymal transformation hypothesis that epithelial root sheath cells differentiate into cementoblasts. However, to date, the spatial-temporal behavior of epithelial root sheath cells and its mechanism has not been elucidated.The immunohistochemisty demonstrated that a certain kind of heat shock protein was expressed continuously from the epithelial cells to the cementblasts on the root dentin and that a certain kind of aquapolin and S100 protein were expressed in the cementoblasts in the rat incisor. The expression pattern of these proteins during cementum formation illustrates the complex origin of cementblasts and the fate of epithelial root sheath cells. These results suggest mesenchymal transition in odontogenic epithelium and the importance of these proteins during the cement genesis. Less