Fibroblast Growth Factor Signaling in Odontogenic Epithelial Stem Cells

描述（由申请人提供）：牙齿缺陷和损坏是影响大多数人一生的常见公共卫生问题。牙齿生物工程和牙齿再生可以在未来解决这一健康问题。全面了解调节牙齿干细胞自我更新和分化的分子和细胞过程对构建新牙至关重要。目前，牙间充质干细胞的研究取得了重大进展。然而，对牙源性上皮干细胞（OESCs）的研究尚不充分，也没有合适的体外培养系统用于OESCs的扩增和分析。成纤维细胞生长因子（FGF）信号轴已被证明在颈环的发育和存活中起重要作用，颈环是支持小鼠门牙终身生长的干细胞生态位。在本项目中，我们将利用新开发的OESCs体外培养系统和基因工程小鼠模型来研究FGF信号轴对OESCs存活、自我更新和分化的调控机制。我们将首先优化OESC球培养条件，并研究如何通过操纵FGF信号轴诱导OESC谱系承诺和分化。下一步，我们将开发OESC的富集方法和OESC后代的谱系追踪方法。然后，我们将确定FGF信号轴是否对OESCs的存活、自我更新和分化是必需的。这些研究将促进我们对自我更新、扩张和分化如何在一般情况下受到调节的理解；这一发现可能会使大量有缺陷或受损牙齿的男性和女性受益，并将指导未来以干细胞为基础的牙齿生物工程的努力。该项目具有很高的创新性，因为它首次了解了OESC的生存、自我更新和分化是如何受到调节的。新的基因工程小鼠模型和新的OESC培养系统将被开发出来，与目前可用的系统一起，也将使牙齿研究界受益。

DESCRIPTION (provided by applicant): Defective and damaged teeth are a common public health problem affecting the majority of human being throughout their lifespan. Tooth bioengineering and regeneration can have a premise future to tackle this health issue. A thorough understanding of molecular and cellular processes that regulate tooth stem cell self-renewal and differentiation is crucial to build new teeth. Currently, significant progresses have been made in tooth mesenchymal stem cells research. Yet, odontogenic epithelial stem cells (OESCs) are understudied and no suitable in vitro culture system is available for expansion and analyses of OESCs. The fibroblast growth factor (FGF) signaling axis has been shown plays important roles in development and survival of the cervical loop, a stem cell niche that supports the lifelong growth of mouse incisors. In this project, we will use the newly developed in vitro culture systems for OESCs and the genetically engineered mouse models to study the mechanisms that underlie regulation of survival, self- renewal, and differentiation of OESCs by the FGF signaling axis. We will first optimize the OESC sphere culture conditions, and study how to induce OESC lineage commitment and differentiation by manipulation of the FGF signaling axis. Next, we will develop methods for enriching OESCs and for lineage tracing of OESC progeny. We will then determine whether the FGF signaling axis is required for the survival, self-renewal, and differentiation of OESCs. These studies will advance our understanding of how self-renewal, expansion, and differentiation are regulated in general; the findings will likely benefit a large number of men and women with defective or damaged teeth, and will guide future efforts aimed at stem cell-based tooth bioengineering. The project is highly innovative since it is the first to understand how survival, self-renewal, and differentiation of OESC are regulated. Novel genetically engineered mouse models and novel OESC culture systems will be developed, which, together with currently available ones, will also benefit the tooth research community.