Hematopoietic Growth Factors and Chronic Stroke

描述(申请人提供)：中风是一种在老年人中发病率较高的神经疾病，是全球成年人长期残疾的主要原因。在美国，中风也是一个巨大的公共卫生问题和严重的公共经济负担。慢性卒中是指卒中发病后3-6个月以上的时间。目前，慢性中风患者还没有药物治疗。干细胞因子(SCF)和粒细胞集落刺激因子(G-CSF)是调节血细胞生成和动员骨髓干细胞(BMSCs)进入血液的造血生长因子(HGFs)。我们最近的研究表明，SCF和G-CSF的受体是由神经元表达的，SCF和G-CSF都可以通过血脑屏障，更重要的是，SCF和G-CSF联合应用对卒中大鼠模型显示出治疗效果。然而，SCFCSF如何修复慢性中风期间永久性受损的大脑仍是完全未知的。这个项目的目标是解决这个悬而未决的问题。有大量的初步数据支持，中心假说是，神经元网络重构有助于SCFCSF诱导的慢性卒中功能恢复，神经元网络重构是通过SCFCSF对神经元的直接作用和通过骨髓间充质干细胞的间接作用完成的。在老年自发性高血压大鼠和仅在神经元中表达黄色或青色荧光蛋白的老年野生型或转基因C57BL小鼠(Thy-1-YFP，Thy-1-CFP)中，神经元和BMSC培养与中风模型一起使用，以及骨髓移植跟踪BMSCs，这一假设将通过追求两个特定目标来验证。目的1确定SCF-CSF对慢性卒中患者的功能益处是否依赖于MEK/ERK和PI3K/Akt通路介导的神经元网络重构。将使用蛋白质印迹、细胞信号阻断、RNA干扰、双光子实时成像和神经功能缺陷检查。目的#2确定SCFCSF建立的S100A8/A9化学梯度在BMSCs归巢到脑中的作用，并确定BMSCs在SCFCSF诱导的慢性卒中功能恢复中的作用。骨髓间充质干细胞迁移分析、S100A8/A9基因RNA干扰沉默和感觉运动功能评估将被用于。这项拟议的研究意义重大，因为它将促进和扩大对HGFs如何在中风造成永久性损伤后修复大脑的理解。此外，它还将为开发一种治疗慢性中风的独特治疗策略做出重大贡献。这一贡献符合美国国立卫生研究院减轻疾病和残疾造成的国家和个人负担的使命。 公共卫生相关性：拟议的研究集中在一个非常重要但调查不足的主题上：一种治疗老年人群慢性中风的新治疗策略。这项研究与公共健康直接相关。这一发现可以为造血生长因子在脑修复中的作用提供新的见解。此外，这一知识还可能导致开发其他神经疾病和神经退行性疾病的新疗法。

DESCRIPTION (provided by applicant): Stroke, a neurological disorder with a high incidence in the elderly, is a leading cause of long-term disability in adults worldwide. Stroke is also an enormous public health problem and a serious public financial burden in the United States. Chronic stroke is identified as the period beyond 3-6 months after stroke onset. Currently, no pharmaceutical treatment is available for chronic stroke victims. Stem cell factor (SCF) and granulocyte- colony stimulating factor (G-CSF) are hematopoietic growth factors (HGFs) that regulate blood cell production and mobilize bone marrow stem cells (BMSCs) into the blood. Our recent publications have shown that the receptors for SCF and G-CSF are expressed by neurons, that both SCF and G-CSF can pass through the blood-brain barrier, and, more importantly, that SCF in combination with G-CSF (SCFCSF) shows therapeutic benefits for chronic stroke in a rat model of stroke. However, it remains entirely unknown how SCFCSF repairs a permanently damaged brain during chronic stroke. The objective of this project is to address this unanswered question. Supported by considerable preliminary data, the central hypothesis is that neuronal network remodeling contributes to SCFCSF-induced functional recovery in chronic stroke and that the neuronal network remodeling is accomplished by the direct effects of SCFCSF on neurons and the indirect effects via BMSCs. Using neuronal and BMSC cultures together with stroke models in aged spontaneously hypertensive rats and in aged wild type or transgenic C57 BL mice expressing yellow or cyan fluorescent proteins only in neurons (Thy-1-YFP, Thy-1-CFP), and bone marrow transplantation to track BMSCs, this hypothesis will be tested by pursuing two specific aims. Aim #1 is to determine whether SCF CSF-induced functional benefits in chronic stroke are dependent upon MEK/ERK and PI3k/Akt pathway- mediated neuronal network remodeling. Western blots, cell signaling blockade, RNA interference, 2-photon live imaging and neurological deficit examinations will be used. Aim #2 is to identify the role of the S100A8/A9 chemical gradient established by SCFCSF in homing BMSCs to the brain and to determine the contribution of the BMSCs to SCFCSF-induced functional recovery from chronic stroke. BMSC migration assays, S100A8/A9 gene silencing by RNA interference, and sensorimotor functional evaluation will be utilized. The proposed research is significant because it will advance and extend understanding of how HGFs repair the brain after permanent damage by stroke. Additionally, it will significantly contribute to the development of a unique therapeutic strategy for treatment of chronic stroke. This contribution is in keeping with the NIH mission to reduce national and personal burdens caused by illness and disability. PUBLIC HEALTH RELEVANCE: The proposed study focuses on a highly important, but under-investigated topic: a new therapeutic strategy to treat chronic stroke in the aged population. This research is directly relevant to public health. The findings can provide fresh insights into the contribution of hematopoietic growth factors in brain repair. Additionally, this knowledge may also lead to the development of new treatments for other neurological disorders and neurodegenerative diseases.