Keller Laetitia-Véronique, Kuchler-Bopp Sabine, Lesot Hervé
INSERM UMR977 Biomatériaux et ingénierie Tissulaire, Strasbourg, France.
Int J Dev Biol. 2012;56(9):737-46. doi: 10.1387/ijdb.120076hl.
Tooth development is controlled by reciprocal epithelial-mesenchymal interactions. Complete teeth can form when culturing and implanting re-associations between single embryonic dental epithelial and mesenchymal cells. Although epithelial histogenesis is clear, very little is known about cell diversity and patterning in the mesenchyme. The aim of this work was to compare the situation in engineered and developing teeth at similar developmental stages. To this end, the expression of cell surface markers in the mesenchyme was investigated by immunostaining in: 1) embryonic mouse molars at embryonic day 14, as the initial cell source for re-associations, 2) cultured cell re-associations just before their implantation and 3) cultured cell re-associations implanted for two weeks. Surface markers allowed visualization of the complex patterning of different cell types and the differential timing in their appearance. The phenotype of mesenchymal cells rapidly changed when they were grown as a monolayer, even without passage. This might explain the rapid loss of their potential to sustain tooth formation after re-association. Except for markers associated with vascularization, which is not maintained in vitro, the staining pattern in the mesenchyme of cultured re-associations was similar to that observed in situ. After implantation, vascularization and the cellular heterogeneity in the mesenchyme were similar to what was observed in developing molars. Besides tissue oxygenation and its role in mineralization of dental matrices, vascularization is involved in the progressive increase in mesenchymal cell heterogeneity, by allowing external cells to enter the mesenchyme.
牙齿发育受上皮-间充质相互作用的调控。当培养并植入单个胚胎牙上皮细胞与间充质细胞重新组合的结构时，完整的牙齿能够形成。尽管上皮组织发生过程已清晰明了，但对于间充质中的细胞多样性和模式形成却知之甚少。这项工作的目的是比较工程化牙齿和处于相似发育阶段的发育中牙齿的情况。为此，通过免疫染色研究了间充质中细胞表面标志物的表达情况，具体如下：1）胚胎第14天的胚胎小鼠磨牙，作为重新组合的初始细胞来源；2）培养的细胞重新组合结构在植入前；3）培养的细胞重新组合结构植入两周后。表面标志物能够使不同细胞类型的复杂模式以及它们出现的不同时间可视化。间充质细胞在单层培养时，即使未传代，其表型也会迅速改变。这可能解释了重新组合后它们维持牙齿形成潜力的快速丧失。除了与血管生成相关的标志物（在体外无法维持）外，培养的重新组合结构中间充质的染色模式与原位观察到的相似。植入后，间充质中的血管生成和细胞异质性与发育中的磨牙相似。除了组织氧合及其在牙基质矿化中的作用外，血管生成还通过允许外部细胞进入间充质，参与间充质细胞异质性的逐渐增加。
