Prospective Purification of Adult Stem Cell Astrocytes

描述(申请人提供)：干细胞在成年哺乳动物大脑的有限区域不断产生新的神经元。脑室下区(SVZ)是成人最大的生发区，可产生迁移到嗅球的神经元和一些少突胶质细胞。体内干细胞是星形胶质细胞的一个子集，星形胶质细胞通常与支持功能有关。这些内源性干细胞可能代表着一个细胞池，可以用来进行大脑修复。内在和外在信号之间的平衡调节静止干细胞的激活。然而，由于缺乏标记物，区分静止和激活干细胞的能力一直受到阻碍。在这里，我们识别了一组标记，使我们能够直接从体内的利基环境中识别和分离SVZ中的四组星形胶质细胞。基于细胞周期分析、体外干细胞行为和基因表达谱，我们推测它们对应于静止的干细胞星形胶质细胞、激活的干细胞星形胶质细胞和小生境星形胶质细胞。我们建议：1)确定纯化的星形胶质细胞群体的细胞周期动力学，以及它们在体外作为干细胞的能力，以及它们的数量和功能特性如何随着年龄的变化而变化；2)在动态平衡和再生过程中对静止和激活的干细胞进行谱系追踪；3)确定PDGFRb在调节成人神经干细胞静止中的作用。总而言之，这些研究将对成人大脑中干细胞静止的调节产生关键的见解。

DESCRIPTION (provided by applicant): Stem cells continuously generate new neurons in restricted regions of the adult mammalian brain. The subventricular zone (SVZ) is the largest germinal region in the adult gives rise to neurons that migrate to the olfactory bulb as well as some oligodendrocytes. The in vivo stem cells are a subset of astrocytes, glial cells classically associated with support functions. These endogenous stem cells potentially represent a pool of cells that can be harnessed for brain repair. A balance between intrinsic and extrinsic signals mediates the activation of quiescent stem cells. However, the ability to distinguish between quiescent and activated stem cells has been hampered by a lack of markers. Here we identify a combination of markers that allow us to identify and isolate four populations of astrocytes from the SVZ directly from the in vivo niche. Based on cell cycle analysis, in vitro stem cell behavior and gene expression profiling, we hypothesize that they correspond to quiescent stem cell astrocytes, activated stem cell astrocytes and niche astrocytes. We propose to: 1) Define the cell cycle kinetics of the purified astrocyte populations, and their ability to act as stem cells in vitro, as well as how their numbers and functional properties change with aging, 2) perform lineage tracing of quiescent and activated stem cells under homeostasis and during regeneration and 3) define the role of PDGFRb in regulating adult neural stem cell quiescence. Together these studies will yield key insights into the regulation of stem cell quiescence in the adult brain.