Dissecting the aging of hematopoietic stem cells by genetic tracing in vivo

描述(申请人提供)：哺乳动物骨髓(BM)中的造血干细胞(HSCs)在整个生命过程中不断产生各种血细胞。在衰老过程中，HSC的活性以多种异常为特征，这些异常阻止了外周淋巴细胞的补充，并极大地增加了骨髓增生性疾病和白血病的风险。为了了解与年龄相关的HSC损伤的确切机制，有必要分析内源性HSC在完整衰老生物体中的功能。这项任务一直难以完成，因为HSC分析的标准方法依赖于细胞分离并转移到受辐射的受者体内。我们已经建立了一种系统，可以对内源性HSCs进行特定标记，并在完好的小鼠身上追踪其后代。这个新的系统将被用来表征内源性HSCs在衰老过程中的功能，使用三个特定的目标。在目标1中，内源性HSCs的自我更新和分化将在老年动物和幼年动物中表现出来。在目的2中，我们将分析衰老过程中HSC的克隆动力学。在目标3中，将研究DNA甲基化调节因子在内源性HSCs功能中的作用。总而言之，这些研究将直接检查未经处理的HSCs在衰老过程中的特性，并阐明与衰老相关的造血异常的机制。

DESCRIPTION (provided by applicant): Hematopoietic stem cells (HSCs) in the mammalian bone marrow (BM) continuously give rise to all blood cell types throughout the entire life. The HSC activity in aging is characterized by multiple abnormalities that prevent the replenishment of peripheral lymphocytes and greatly increase the risk of myeloproliferative disorders and leukemia. To understand precise mechanisms of age-associated HSC impairment, it is necessary to analyze the function of endogenous HSCs in intact aging organisms. This task has been elusive, as standard methods of HSC analysis rely on cell isolation and transfer into irradiated recipients. We have generated a system that allows specific labeling of endogenous HSCs and tracing of their progeny in intact mice. This novel system will be used to characterize the function of endogenous HSCs in aging, using three Specific Aims. In Aim 1, the self- renewal and differentiation of endogenous HSCs will be characterized in old versus young animals. In Aim 2, the clonal dynamics of HSC compartment during aging will be analyzed. In Aim 3, the role of DNA methylation regulators in the function of endogenous HSCs will be studied. Collectively, these studies would directly examine the properties of unmanipulated HSCs during aging, and clarify the mechanisms of aging-associated abnormalities of hematopoiesis.