Honda Masaki J, Sumita Yoshinori, Kagami Hideaki, Ueda Minoru
Division of Stem Cell Engineering, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
Arch Histol Cytol. 2005 Jun;68(2):89-101. doi: 10.1679/aohc.68.89.
The successful regeneration of complex tooth structures based on tissue-engineering principles was recently reported. The process of this regeneration, however, remains poorly characterized. In this study, we have used histochemistry to examine the regeneration process of tissue engineered teeth in order to determine the cell types that give rise to these engineered tooth structures. Porcine third molar tooth buds were dissociated into single-cell suspensions and seeded onto a biodegradable polyglycolic acid polymer scaffold. Following varying periods of growth in rat hosts, the specimens were evaluated by histology and immunohistochemistry. Aggregates of epithelial cells were first observed 4-6 weeks after implantation. These aggregates assumed three different shapes: a natural tooth germ-like shape, a circular shape, or a bilayer-bundle. Based on the structure of the stellate reticulum in the dental epithelium, the circular and bilayer-bundle aggregates could be clearly classified into two types: one with extensively developed stellate reticulum, and the other with negligible stellate reticulum. The epithelial cells in the circular aggregates differentiated into ameloblasts. The continuous bilayer bundles eventually formed the epithelial sheath, and dentin tissue was evident at the apex of these bundles. Finally, enamel-covered dentin and cementum-covered dentin formed, a process most likely mediated by epithelial-mesenchymal interaction. These results suggest that the development of these engineered teeth closely parallels that of natural odontogenesis derived from the immature epithelial and mesenchymal cells.
最近有报道称基于组织工程原理成功实现了复杂牙齿结构的再生。然而，这种再生过程的特征仍不清楚。在本研究中，我们使用组织化学方法来检查组织工程牙齿的再生过程，以确定形成这些工程化牙齿结构的细胞类型。将猪第三磨牙牙胚解离成单细胞悬液，并接种到可生物降解的聚乙醇酸聚合物支架上。在大鼠宿主体内生长不同时间段后，通过组织学和免疫组织化学对标本进行评估。植入后4 - 6周首次观察到上皮细胞聚集体。这些聚集体呈现出三种不同形状：天然牙胚样形状、圆形或双层束状。根据牙上皮中星网状层的结构，圆形和双层束状聚集体可明确分为两种类型：一种星网状层广泛发育，另一种星网状层可忽略不计。圆形聚集体中的上皮细胞分化为成釉细胞。连续的双层束最终形成上皮鞘，在这些束的顶端可见牙本质组织。最后，形成了釉质覆盖的牙本质和牙骨质覆盖的牙本质，这一过程很可能是由上皮 - 间充质相互作用介导的。这些结果表明，这些工程化牙齿的发育与源自未成熟上皮和间充质细胞的天然牙发生过程密切相似。
