尽管新的生物工程技术不断涌现，但是利用干细胞构建牙齿仍然是一个遥远的目标。为了构建牙齿，人们需要一种详细的配方来指导细胞分化为合适的细胞系和形成牙齿细胞。然而，研究牙齿干细胞(dental stem cell)需要将它们分离，而且特异性标记物缺乏一直阻碍着人们对它们进行研究。
在一项新研究中，来自芬兰赫尔辛基市生物技术研究所的Irma Thesleff教授领导的一个研究小组发现牙齿干细胞中的一个标记物。他们证实Sox2在小鼠门牙(front tooth)干细胞中特异性地表达。小鼠门牙在一生当中都不断地生长，而且这种生长是由位于牙齿根部的干细胞促进的。这些细胞提供一种极好的模型来研究牙齿干细胞。
研究人员开发出一种方法来记录牙齿干细胞的分裂、运动和分化。通过追踪基因标记的细胞，他们也证实Sox2阳性干细胞产生形成牙釉质的成釉细胞(ameloblast)和牙齿中其他细胞系。
尽管人牙齿不能持续性地生长，但是控制和调节牙齿生长的机制与小鼠牙齿相类似。因此，发现牙齿干细胞标记物Sox2是朝开发出完整的生物工程牙齿而迈出的重要一步。在未来，人们可能利用牙齿干细胞培育出新的牙齿来替换缺损的牙齿。(生物谷：Bioon.com)
本文编译自One Step Closer to Growing a Tooth
doi: 10.1016/j.devcel.2012.05.012
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Sox2+ Stem Cells Contribute to All Epithelial Lineages of the Tooth via Sfrp5+ Progenitors
Emma Juuri, Kan Saito, Laura Ahtiainen, Kerstin Seidel, Mark Tummers, Konrad Hochedlinger, Ophir D. Klein, Irma Thesleff, Frederic Michon
The continuously growing mouse incisor serves as a valuable model to study stem cell regulation during organ renewal. Epithelial stem cells are localized in the proximal end of the incisor in the labial cervical loop. Here, we show that the transcription factor Sox2 is a specific marker for these stem cells. Sox2+ cells became restricted to the labial cervical loop during tooth morphogenesis, and they contributed to the renewal of enamel-producing ameloblasts as well as all other epithelial cell lineages of the tooth. The early progeny of Sox2-positive stem cells transiently expressed the Wnt inhibitor Sfrp5. Sox2 expression was regulated by the tooth initiation marker FGF8 and specific miRNAs, suggesting a fine-tuning to maintain homeostasis of the dental epithelium. The identification of Sox2 as a marker for the dental epithelial stem cells will facilitate further studies on their lineage segregation and differentiation during tooth renewal.
