Project 4: Impact of cardiovascular disease on proliferation and genetic diversity of hematopoietic stem cells

项目4：心血管疾病对造血干细胞增殖和遗传多样性的影响

• 批准号: 10670736
• 负责人: Kamila Naxerova
• 金额: $ 41.32万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10670736
• 关键词: Acceleration; Acute; Address; Affect; Age; Aging; Atherosclerosis; Bar Codes; Behavior; Blood; Bone Marrow; Bone Marrow Purging; Cardiovascular Diseases; Cell Compartmentation; Cells; Chronic; Clonal Expansion; Clonal Hematopoietic Stem Cell; Collaborations; Collection; Complement; DNA; Data; Development; Disease; Disease model; Etiology; Evolution; Exhibits; Experimental Models; Gene Library; Genes; Genetic; Genetic Drift; Genetic Models; Genetic Variation; Genotype; Goals; Hematopoiesis; Hematopoietic; Hematopoietic stem cells; Human; Immune; Incidence; Individual; Inflammatory; Lentivirus; Letters; Measures; Methodology; Methods; Modeling; Mus; Mutate; Mutation; Myocardial Infarction; Nature; Patients; Pattern; Peripheral; Phenotype; Population; Population Dynamics; Process; Proliferating; Proteins; Role; Scientist; Testing; Time; Titrations; Transplantation; Untranslated RNA; Work; atherosclerosis risk; cardiovascular disorder risk; clinically relevant; exhaustion; experience; experimental study; genetic analysis; in silico; in vivo; insertion/deletion mutation; insight; interest; mathematical model; mouse model; next generation; novel; peripheral blood; self-renewal; stem cell population; stem cell proliferation

During aging, descendants of individual hematopoietic stem cell (HSC) clones can begin dominating significant portions of the peripheral blood, a phenomenon called clonal hematopoiesis (CH). CH has recently been shown to correlate with an increased risk for CVD. The mechanisms behind this association are only beginning to be explored. Existing studies have focused on examining how driver genes that are frequently mutated in CH affect the inflammatory phenotype of peripheral immune cells that drive CVD. Here, we propose to investigate the possibility of reverse causality. We will study how CVD influences HSC evolution and CH emergence, using mathematical modeling and novel experimental methods. In aim 1, we will construct a mathematical model of somatic HSC evolution in steady state and CVD. Myocardial infarction has been shown to double the proliferation rate of HSCs. Furthermore, our unpublished preliminary data, collected in collaboration with other PPG projects, show that atherosclerosis can similarly increase the proliferation of HSCs by up to 2.5-fold. We hypothesize that chronically elevated proliferation in the HSC compartment accelerates CH due to neutral drift and/or due to accelerated emergence of clones with a selective advantage. To test these hypotheses, we will construct a stochastic branching process model of genetic diversity in the HSC population over a human lifetime. We will begin by studying neutral drift alone and will then carefully expand our model to include the occurrence of beneficial mutations. Results from this aim will elucidate the role of HSC proliferation in CH emergence and provide a firm quantitative basis for future research into the mechanisms of CH. In aim 2, we will investigate experimentally whether CVD causes clonal hematopoiesis in mice. We will establish murine models of CH and test our hypothesis that increased HSC proliferation rates caused by CVD enhance CH. We will use polyguanine genotyping, a genetic analysis that relies on non-coding, hypermutable DNA repeats which rapidly accumulate insertion/deletion mutations, to measure with high sensitivity whether clonal expansions occur in the blood of aging mice. We will then determine whether the incidence of CH is significantly increased in two CVD models (atherosclerosis and myocardial infarction). In Aim 2B, we will study CVD and CH in a transplantation setting. We will isolate and transduce highly purified LT-HSC populations with a lentivirus carrying a library of genetic barcodes, along with a collection of seven fluorescent proteins that can be used to track clonal dynamics in vivo. We will then transplant tagged HSCs into myeloablated hosts, titrating their numbers such that CH emerges within a relatively short time frame. Finally, we will induce myocardial infarction and atherosclerosis and score the incidence of CH in comparison to age-matched controls. In conjunction with our in silico approach in aim 1, we anticipate that these experiments will provide fundamental insights into how HSC population dynamics are influenced by CVD.

在衰老过程中，单个造血干细胞（HSC）克隆的后代可以开始显著地支配造血干细胞（HSC）。 部分外周血，一种称为克隆造血（CH）的现象。CH最近在 与心血管疾病风险增加有关。这种关联背后的机制才刚刚开始 有待探索现有的研究主要集中在研究驱动基因是如何频繁突变的， CH影响驱动CVD的外周免疫细胞的炎性表型。在此，我们建议 调查反向因果关系的可能性。我们将研究CVD如何影响HSC的演变和CH 出现，使用数学建模和新颖的实验方法。在目标1中，我们将构建一个 稳态和CVD中的体细胞HSC进化的数学模型。心肌梗死已经被证明 使造血干细胞的增殖率加倍。此外，我们未发表的初步数据，收集在 与其他PPG项目的合作表明，动脉粥样硬化可以类似地增加 HSCs增加了2.5倍。我们推测，HSC区室中的慢性增殖升高 由于中性漂变和/或由于具有选择优势的克隆的加速出现而加速CH。 为了验证这些假设，我们将构建一个随机分枝过程模型的遗传多样性， 人类一生中的HSC数量。我们将开始只研究中性漂移， 扩展我们的模型，包括有益突变的发生。这一目标的结果将阐明 HSC增殖在CH出现中的作用，并为未来研究HSC增殖在CH发生中的作用提供了坚实的定量基础。 在目标2中，我们将通过实验研究CVD是否会导致克隆性造血， 小鼠我们将建立小鼠CH模型，并验证我们的假设，即HSC增殖率增加 我们将使用聚鸟嘌呤基因分型，一种依赖于非编码的遗传分析， 快速积累插入/缺失突变的高变DNA重复序列，以测量高 衰老小鼠血液中是否发生克隆扩增的敏感性。然后我们将确定 在两种CVD模型（动脉粥样硬化和心肌梗死）中CH的发病率显著增加。在 目的2B，我们将研究移植环境中的CVD和CH。我们将分离并高度纯化 LT-HSC群体具有携带遗传条形码文库的慢病毒，沿着有七个 荧光蛋白，可用于跟踪体内克隆动力学。然后我们将标记的HSC 进入骨髓清除的宿主，滴定它们的数量，使得CH在相对较短的时间内出现。 最后，我们将诱发心肌梗死和动脉粥样硬化并对CH的发生率进行评分， 年龄匹配的对照组。结合我们在目标1中的计算机模拟方法，我们预计这些 实验将提供基本的见解，HSC的人口动态是如何影响CVD。