The Jackson Laboratory, Bar Harbor, ME.
The Jackson Laboratory, Bar Harbor, ME.
Exp Hematol. 2020 Nov;91:1-9. doi: 10.1016/j.exphem.2020.09.197. Epub 2020 Sep 28.
Over the past 25 years, the importance of hematopoietic stem cell (HSC) aging in overall hematopoietic and immune system health span has been appreciated. Much work has been done in model organisms to understand the intrinsic dysregulation that occurs in HSCs during aging, with the goal of identifying modifiable mechanisms that represent the proverbial "fountain of youth." Much more recently, the discovery of somatic mutations that are found to provide a selective advantage to HSCs and accumulate in the hematopoietic system during aging, termed clonal hematopoiesis (CH), inspires revisiting many of these previously defined drivers of HSC aging in the context of these somatic mutations. To truly understand these processes and develop a holistic picture of HSC aging, ongoing and future studies must include investigation of the critical changes that occur in the HSC niche or bone marrow microenvironment with aging, as increasing evidence supports that these HSC-extrinsic alterations provide necessary inflammation, signaling pathway activation or repression, and other selective pressures to favor HSC aging-associated phenotypes and CH. Here, we provide our perspectives based on the past 8 years of our own laboratory's investigations into these mechanisms and chart a path for integrative studies that, in our opinion, will provide an ideal opportunity to discover HSC and hematopoietic health span-extending interventions. This path includes examining when and how aging-associated HSC-intrinsic and HSC-extrinsic changes accumulate over time in different individuals and developing new models to track and test relevant HSC-extrinsic changes, complementary to innovative HSC lineage tracing systems that have recently been developed.
在过去的 25 年中,造血干细胞(HSC)衰老在整体造血和免疫系统健康寿命中的重要性已得到认可。在模式生物中已经进行了大量工作来了解 HSC 在衰老过程中发生的内在失调,其目标是确定可修饰的机制,这些机制代表了众所周知的“青春之泉”。最近,人们发现了体细胞突变,这些突变被认为为 HSC 提供了选择性优势,并在衰老过程中在造血系统中积累,称为克隆性造血(CH),这激发了重新审视这些先前定义的 HSC 衰老驱动因素在这些体细胞突变背景下的作用。为了真正理解这些过程并全面了解 HSC 衰老,正在进行和未来的研究必须包括研究 HSC 龛或骨髓微环境随衰老而发生的关键变化,因为越来越多的证据支持这些 HSC 细胞外改变提供必要的炎症、信号通路激活或抑制以及其他选择性压力,以有利于 HSC 衰老相关表型和 CH。在这里,我们根据我们实验室过去 8 年对这些机制的研究提供了我们的观点,并为综合研究制定了一个路径,我们认为这将是发现 HSC 和造血健康寿命延长干预措施的理想机会。这条路径包括检查随着时间的推移,衰老相关的 HSC 内在和 HSC 外在变化在不同个体中何时以及如何积累,并开发新的模型来跟踪和测试相关的 HSC 外在变化,这些模型与最近开发的创新 HSC 谱系追踪系统相辅相成。