Hematopoietic Growth Factors and Chronic Stroke

描述（由申请人提供）：中风是一种在老年人中发病率较高的神经系统疾病，是全世界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财政负担。慢性中风被定义为中风发作后超过 3-6 个月的时期。目前，还没有针对慢性中风患者的药物治疗。干细胞因子 (SCF) 和粒细胞集落刺激因子 (G-CSF) 是造血生长因子 (HGF)，可调节血细胞生成并将骨髓干细胞 (BMSC) 动员到血液中。我们最近的出版物表明，SCF 和 G-CSF 的受体由神经元表达，SCF 和 G-CSF 都可以穿过血脑屏障，更重要的是，SCF 与 G-CSF 组合 (SCFCSF) 在中风大鼠模型中显示出对慢性中风的治疗益处。然而，SCFCSF 如何修复慢性中风期间永久受损的大脑仍然完全未知。该项目的目标是解决这个悬而未决的问题。在大量初步数据的支持下，中心假设是神经元网络重塑有助于 SCFCSF 诱导的慢性中风功能恢复，并且神经元网络重塑是通过 SCFCSF 对神经元的直接影响和通过 BMSC 的间接影响来完成的。使用神经元和 BMSC 培养物以及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（Thy-1-YFP、Thy-1-CFP）的老年野生型或转基因 C57 BL 小鼠的中风模型，以及骨髓移植来追踪 BMSC，将通过追求两个特定目标来检验这一假设。目标 #1 是确定 SCF CSF 诱导的慢性中风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塑。将使用蛋白质印迹、细胞信号传导阻断、RNA干扰、2光子实时成像和神经功能缺损检查。目标 #2 是确定 SCFCSF 建立的 S100A8/A9 化学梯度在 BMSC 归巢至大脑中的作用，并确定 BMSC 对 SCFCSF 诱导的慢性中风功能恢复的贡献。将利用 BMSC 迁移测定、RNA 干扰引起的 S100A8/A9 基因沉默以及感觉运动功能评估。拟议的研究意义重大，因为它将推进和扩展对 HGF 如何修复中风永久性损伤后大脑的理解。此外，它将显着有助于开发治疗慢性中风的独特治疗策略。这项捐款符合 NIH 减轻疾病和残疾造成的国家和个人负担的使命。 公共健康相关性：拟议的研究重点关注一个非常重要但研究不足的主题：治疗老年人群慢性中风的新治疗策略。这项研究与公共卫生直接相关。这些发现可以为造血生长因子在大脑修复中的贡献提供新的见解。此外，这些知识还可能导致其他神经系统疾病和神经退行性疾病的新疗法的开发。

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.