Morotomi Takahiko, Kawano Shintaro, Toyono Takashi, Kitamura Chiaki, Terashita Masamichi, Uchida Takashi, Toyoshima Kuniaki, Harada Hidemitsu
Department of Operative Dentistry and Endodontics, Kyushu Dental College, Kokurakita-ku, Kitakyushu, Japan.
Arch Oral Biol. 2005 Aug;50(8):695-705. doi: 10.1016/j.archoralbio.2004.12.006. Epub 2005 Feb 26.
In developing teeth, dental epithelial progenitor cells differentiate through sequential and reciprocal interactions with neural-crest-derived mesenchyme. However, the molecular mechanisms involved in cell differentiation are not well understood. Continuously growing teeth are useful in the study of differentiation of dental progenitor cells. In rat lower incisors, ameloblasts originate from the dental epithelial adult stem cell compartment referred to as the 'apical bud'. To elucidate the mechanism of ameloblast differentiation, we designed a primary culture system and confirmed the differentiation of dental epithelial cells through interaction with mesenchymal cells. Cytokeratin was used as a marker for epithelial cells, nerve growth factor receptor p75 for inner enamel epithelial (IEE) cells, and ameloblastin for ameloblasts. The apical bud cells could only differentiate into IEE cells and, within 10 days, into ameloblasts expressing ameloblastin in the presence of dental papilla cells. Interestingly, the IEE cells could proliferate transiently and differentiate into ameloblasts in the presence or absence of dental papilla cells. These results suggest that apical bud cells can enter the ameloblast cell lineage through interaction with mesenchymal cells. IEE cells, on the other hand, are already committed to differentiate into ameloblasts. This culture system is useful in future studies of ameloblast differentiation.
在牙齿发育过程中，牙上皮祖细胞通过与神经嵴来源的间充质进行顺序性和相互性的相互作用而分化。然而，细胞分化所涉及的分子机制尚未完全清楚。持续生长的牙齿对于研究牙祖细胞的分化很有用。在大鼠下切牙中，成釉细胞起源于被称为“根尖芽”的牙上皮成体干细胞区室。为了阐明成釉细胞分化的机制，我们设计了一种原代培养系统，并通过与间充质细胞的相互作用证实了牙上皮细胞的分化。细胞角蛋白用作上皮细胞的标志物，神经生长因子受体p75用作内釉上皮（IEE）细胞的标志物，釉蛋白用作成釉细胞的标志物。在存在牙乳头细胞的情况下，根尖芽细胞只能分化为IEE细胞，并在10天内分化为表达釉蛋白的成釉细胞。有趣的是，在存在或不存在牙乳头细胞的情况下，IEE细胞都可以短暂增殖并分化为成釉细胞。这些结果表明，根尖芽细胞可以通过与间充质细胞的相互作用进入成釉细胞谱系。另一方面，IEE细胞已经注定要分化为成釉细胞。这种培养系统在未来成釉细胞分化的研究中很有用。
