Ambient fine particulate matter and bone marrow stem cells

 描述(由申请人提供)：环境中的细颗粒物(PM)是空气污染的关键成分，与显著的死亡率有关。PM暴露后的大部分死亡与心血管疾病有关。内皮祖细胞是维持血管完整性和功能的关键，骨髓是其主要来源之一。PM暴露对心血管系统表现出多种有害影响，并显著降低内皮祖细胞的数量和功能。然而，PM暴露致内皮祖细胞损伤的机制(S)还不完全清楚。最近，我们观察到PM暴露显著降低了循环内皮祖细胞的水平，S和骨髓中的骨髓干细胞(BMSCs)数量显著减少，同时增加了小鼠体内活性氧物种(ROS)的形成水平。当ROS的产生被阻断时，PM诱导的EPC和BMSCs的减少被有效地阻止。本项目的提出是为了验证这一假设，即PM暴露通过氧化应激介导的骨髓中BMSC数量的减少以及BMSCs产生的EPC数量的减少来减少EPC的数量和功能。有两个特定的目的：1)确定PM暴露对BMSCs及其内皮分化的影响；2)确定氧化应激在PM暴露对BMSCs的影响及其向内皮祖细胞分化中的作用。我们将证明PM暴露会导致骨髓中BMSCs的数量和功能显著减少。我们将确定BMSCs数量的减少是由于凋亡增加还是增殖减少。我们还将利用骨髓移植(BMT)与EGFP阳性的BMSCs进行实验，以确定PM暴露是否会损害BMSCs向EPC的分化，这可能导致PM暴露环境中EPC数量和功能的减少。为了确定PM暴露是否会对骨髓间充质干细胞产生与慢性空气污染类似的影响，这些实验将在暴露在空气污染中长达6个月的小鼠身上重复。我们将测试PM诱导的ROS产生是否通过使用抗氧化剂N-乙酰半胱氨酸或伴随着ROS形成减少的人铜/锌超氧化物歧化酶(SOD)1、细胞外SOD3和谷胱甘肽过氧化物酶的抗氧化酶网络的过度表达来阻断ROS的产生，从而导致BMSCs的数量和功能减少。我们还将使用骨髓移植模型和EGFP-BMSCs来确定PM诱导的氧化应激是否在BMSCs向EPC分化过程中发挥关键作用。实验将评估ROS在BMSCs种群中的作用以及在暴露于空气污染长达6个月的小鼠中向内皮祖细胞分化。这项研究的数据将为PM暴露和空气污染患者心血管疾病的发生机制提供重要的新信息，并有助于探索预防和治疗与PM暴露相关的心血管疾病的新方法。1

 DESCRIPTION (provided by applicant): Ambient fine particulate matter (PM) is the key components for air pollution, and associated with significant mortality. The majority of the mortality following PM exposure is related to cardiovascular diseases. Endothelial progenitor cells (EPCs) are critical to maintaining the integrity and function of blood vessels with bone marrow as one of their main sources. PM exposure exhibits various deleterious effects on cardiovascular system, and significantly decreases the number and function of EPCs. However, the mechanism(s) for PM exposure- induced impairment of EPCs has not been fully understood. Recently, we observed that PM exposure significantly decreased the level of circulating EPCs s and the population of bone marrow stem cells (BMSCs) within the bone marrow in association with increased level of reactive oxygen species (ROS) formation in mice. When ROS production was blocked, PM-induced reduction of EPCs and BMSCs was effectively prevented. The present project was proposed to test the hypothesis that "PM exposure reduces the number and function of EPCs through oxidative stress-mediated reduction of BMSC population in bone marrow with reduced generation of EPCs from BMSCs". There are two specific aims: 1): to determine the effect of PM exposure on BMSCs and their endothelial differentiation; and 2): to define the role of oxidative stress in mediating the effect of PM exposure on BMSCs and their differentiation into EPCs. We will demonstrate that PM exposure leads to a significant reduction in the number and function of BMSCs in the bone marrow. We will determine if the decrease in the number of BMSCs is due to increased apoptosis or decreased proliferation. We will also conduct experiments using bone marrow transplantation (BMT) with eGFP-positive BMSCs to determine if PM exposure impairs the differentiation of BMScs into EPCs that may contribute to decreased number and function of EPCs in the setting of PM exposure. To determine if PM exposure could produce a similar effect on BMSCs as chronic air pollution, the experiments will be repeated using mice exposed to air pollution for up to 6 months. We will test whether PM-induced ROS production causes decreased number and function of BMSCs by blocking ROS production using either antioxidant N-acetylcysteine or concomitant overexpression of an antioxidant enzyme network of human copper/zinc superoxide dismutase (SOD) 1, extracellular SOD3, and glutathione peroxidase with decreased ROS formation. We will also use BMT model with eGFP-BMSCs to determine if PM-induced oxidative stress plays a critical role in the differentiation of BMSCs into EPCs. Experiments will be conducted to evaluate the role of ROS in the population of BMSCs and their differentiation into EPCs in the mice exposed to air pollution for up to 6 months. The data from this study will provide important and novel information on the mechanisms for the development of cardiovascular diseases in patients with PM exposure and air pollution, and help explore new approaches to preventing and treating cardiovascular diseases related to PM exposure. 1