Quantifying Changes in Neural Stem Cell Lineages in the Aging Niche

描述(申请人提供)：这项研究的目标是量化衰老对成年神经干细胞(NSCs)动态和谱系的影响。虽然众所周知，随着年龄的增长，神经干细胞的活动减少，这种下降可能在衰老和与年龄相关的疾病中发挥作用，但一些基本的问题仍然存在。干细胞活性的哪些方面会随着年龄的增长而变化？祖细胞数量、它们在生态位内的活动以及它们的增殖动力学是否发生了变化？祖细胞是随着年龄的增长而改变命运，制造更多的神经胶质细胞而不是神经元，还是经历衰老？另一个重要的悬而未决的问题是，NSC活性的下降是细胞自主变化的结果，还是由于干细胞生态位老化的结果。拟议的研究旨在解决这些重要的悬而未决的问题。我们将确定神经干细胞在青壮年和老年小鼠脑中的谱系和动态特性。这项涉及干细胞生物学家和计算机工程师的合作工作将专注于直接观察-捕获延时图像序列，显示生态位内神经干细胞的动态及其产生的已识别后代。活细胞成像结果将使用最先进的自动化软件工具进行量化和分析，以跟踪干细胞并生成谱系树，使我们能够准确识别不同年龄NSC行为的差异。将为胚胎NSC谱系分析开发的技术应用于成体系统，将使我们能够更全面地了解干细胞的属性和祖细胞关系，成体谱系树的构建，以及这些元素如何随年龄变化。具体地说，这项拟议的研究将通过长期时间推移显微镜确定和比较年轻和老年小鼠脑室下区(SVZ)中神经干细胞的谱系和动态特性。这将为以下重要问题提供洞察力：随着年龄的增长，神经发生的减少是细胞自主的，还是由于通过将干细胞从年轻移植到老年以及从老年移植到年轻的SVZ来改变生态位，并测量移植细胞的整合、谱系和动态性质的变化。此外，它将通过探索趋化因子SDF1和相应的CXCR4受体在衰老过程中所起的作用，来研究与年龄相关的NSC活性下降的分子事件。SDF/CXCR4信号在大脑中随着年龄的增长而下降；CXCR4的表达减少被认为是导致其他组织中干细胞活性下降的原因。在这里，我们将测量年轻人和老年人大脑中SDF1和CXCR4的水平。在年轻和老年小鼠的NSC谱系中，SDF1/CXCR4信号将被特定的CXCR4拮抗剂或条件敲除阻断，并将分析谱系进展的变化。这项工作将有助于了解祖细胞行为的变化可能如何导致癌症和记忆丧失等老年性疾病，并开始确定分子靶点，以缓解成人干细胞利基中与衰老相关的神经退行性变化。

DESCRIPTION (provided by applicant): The goal of this research is to quantify the effect of aging on the dynamics and lineage of adult neural stem cells (NSCs). While it is known that there is reduced NSC activity with aging and that this decline may play a role in aging and age-related diseases, a number of fundamental questions remain. Which aspects of stem cell activity change with aging? Are there changes in the progenitor cell population, their movements within the niche and their proliferation kinetics? Do progenitor cells switch fate with aging, making more glial cells rather than neurons or do they undergo senescence? Another important unresolved issue is whether the declines in NSC activity are the result of cell autonomous changes or due to aging of the stem cell niche. The proposed research is designed to address these important unanswered questions. We will determine the lineage and dynamic properties of NSCs in young adult and aged mouse brains. This collaborative effort involving stem cell biologists and computer engineers will focus on direct observation - capturing time-lapse image sequences showing the dynamics of NSCs within the niche and their production of identified progeny. The live cell imaging results will be quantified and analyzed with state-of-the-art automated software tools for tracking stem cells and generating lineage trees, enabling us to accurately identify differences in NSC behavior at different ages. Applying techniques developed for NSC lineage analysis in embryos to the adult system will allow a much more complete understanding of stem cell properties and progenitor relationships, of the construction of adult lineage trees and how these elements change with age. Specifically, the proposed research will determine and compare the lineage and dynamic properties of NSCs in the subventricular zone (SVZ) in young and aged mice by long-term time lapse microscopy. It will provide insight into the important question of whether decreased neurogenesis with aging is cell autonomous or is due to changes in the niche by transplanting stem cells from young to aged and from aged to young SVZ, and measuring changes in the integration, lineage and dynamic properties of the transplanted cells. Furthermore, it will investigate molecular events underlying age-related declines in NSC activity by exploring the role that the chemokine SDF1 and the corresponding CXCR4 receptor play in the aging process.SDF/CXCR4 signaling declines with age in the brain; reduced CXCR4 expression has been suggested to contribute to a decline in stem cell activity in other tissues. Here we will measure SDF1 andCXCR4 levels in young and aged brains. SDF1 /CXCR4 signaling will be blocked using a specific antagonist or conditional knockout of CXCR4 in the NSC lineage in young and aged mice and changes in lineage progression will be analyzed. This work will provide an understanding of how changes in progenitor behavior might contribute to diseases of aging such as cancer and memory loss and begin to identify molecular targets to alleviate aging- related neurodegenerative changes in the adult stem cell niche.