Keller Laetitia, Kuchler-Bopp Sabine, Mendoza Soledad Acuña, Poliard Anne, Lesot Hervé
UMR 977, Faculté de Médecine, INSERM Strasbourg, France.
Front Physiol. 2011 Mar 4;2:7. doi: 10.3389/fphys.2011.00007. eCollection 2011.
The implantation of cultured re-associations between embryonic dental mesenchymal cells and epithelial cells from mouse molars at embryonic day 14 (ED14) allowed making full teeth with crown, root, periodontal ligament fibers, and bone. Although representing valuable tools to set up methodologies embryonic cells are not easily available. This work thus aimed to replace the embryonic cells by dental mesenchymal cell lines or cultured expanded embryonic cells, and to test their ability to mediate tooth development in vitro when re-associated with a competent dental epithelium. Histology, immunostaining and RT-PCR allowed getting complementary sets of results. Two different immortalized cell lines from ED18 dental mesenchyme failed in mediating tooth formation. The potentialities of embryonic dental mesenchymal cells decreased from ED14 to ED16 and were lost at ED18. This is likely related to a change in the mesenchymal cell phenotype and/or populations during development. Attempts to cultivate ED14 or ED16 embryonic dental mesenchymal cells prior to re-association led to the loss of their ability to support tooth development. This was accompanied by a down-regulation of Fgf3 transcription. Supplementation of the culture medium with FGF2 allowed restoring Fgf3 expression, but not the ability of mesenchymal cells to engage in tooth formation. Altogether, these observations suggest that a competent cell population exists in the dental mesenchyme at ED14, progressively decreases during development, and cannot as such be maintained in vitro. This study evidenced the need for specific conditions to maintain the ability of dental mesenchymal cells to initiate whole tooth formation, when re-associated with an odontogenic epithelium. Efforts to improve the culture conditions will have to be combined with attempts to characterize the competent cells within the dental mesenchyme.
将胚胎第14天（ED14）小鼠磨牙的胚胎牙间充质细胞与上皮细胞进行培养重聚后植入，可形成具有冠、根、牙周韧带纤维和骨的完整牙齿。尽管胚胎细胞是建立方法学的宝贵工具，但并不容易获得。因此，这项工作旨在用牙间充质细胞系或培养扩增的胚胎细胞替代胚胎细胞，并测试它们在与有能力的牙上皮细胞重聚时体外介导牙齿发育的能力。组织学、免疫染色和逆转录聚合酶链反应提供了互补的结果集。来自ED18牙间充质的两种不同的永生化细胞系未能介导牙齿形成。胚胎牙间充质细胞的潜能从ED14到ED16逐渐降低，并在ED18时丧失。这可能与发育过程中间充质细胞表型和/或细胞群的变化有关。在重聚前尝试培养ED14或ED16胚胎牙间充质细胞导致它们支持牙齿发育的能力丧失。这伴随着Fgf3转录的下调。用FGF2补充培养基可恢复Fgf3表达，但不能恢复间充质细胞参与牙齿形成的能力。总之，这些观察结果表明，ED14时牙间充质中存在有能力的细胞群，在发育过程中逐渐减少，并且不能在体外维持。这项研究证明，当与牙源性上皮细胞重聚时，需要特定条件来维持牙间充质细胞启动全牙形成的能力。改善培养条件的努力必须与表征牙间充质中有能力的细胞的尝试相结合。
