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

基本信息

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
项目类别：
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

项目摘要

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 Furthermore, our unpublished preliminary data, collected in collaboration with other PPG projects, show that atherosclerosis can similarly increase the proliferation of HSCs by up to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) 克隆的后代可能开始占据显着的地位。外周血的一部分，这种现象称为克隆造血（CH）。 CH最近被显示与 CVD 风险增加相关。该协会背后的机制才刚刚开始有待探索。现有的研究重点是检查经常突变的驱动基因如何 CH 影响驱动 CVD 的外周免疫细胞的炎症表型。在此，我们建议研究反向因果关系的可能性。我们将研究 CVD 如何影响 HSC 进化和 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体细胞HSC进化的数学模型。已显示心肌梗塞使 HSC 的增殖率加倍。此外，我们未发表的初步数据收集于与其他 PPG 项目的合作表明，动脉粥样硬化同样可以增加增殖 HSC 增加高达 2.5 倍。我们假设 HSC 区室的增殖长期增加由于中性漂移和/或由于具有选择性优势的克隆的加速出现而加速CH。为了检验这些假设，我们将构建遗传多样性的随机分支过程模型人一生中的 HSC 数量。我们将从单独研究中性漂移开始，然后仔细研究扩展我们的模型以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，为未来的研究提供坚实的定量基础 CH 的机制。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老鼠。我们将建立 CH 小鼠模型并检验我们的 HSC 增殖率增加的假设 CVD引起的CH增强。我们将使用多鸟嘌呤基因分型，这是一种依赖于非编码的遗传分析，超可变 DNA 重复序列会快速积累插入/缺失突变，以高通量进行测量衰老小鼠血液中是否发生克隆扩增的敏感性。然后我们将确定是否在两种 CVD 模型（动脉粥样硬化和心肌梗塞）中，CH 的发生率显着增加。在目标 2B，我们将在移植环境中研究 CVD 和 CH。我们将分离并转导高度纯化的带有携带遗传条形码文库的慢病毒的 LT-HSC 群体，以及七个可用于追踪体内克隆动态的荧光蛋白。然后我们将移植标记的 HSC 进入清髓宿主，滴定它们的数量，使得 CH 在相对较短的时间内出现。最后，我们将诱发心肌梗塞和动脉粥样硬化，并对CH的发生率进行评分比较到年龄匹配的控制。结合我们目标 1 中的计算机方法，我们预计这些实验将为了解 CVD 如何影响 HSC 群体动态提供基本见解。