A Novel Intervention for Cerebral Ischemia

描述(由申请人提供)： 在美国，中风是导致成年人长期残疾的主要原因，目前还没有可用的疗法来预防中风引起的神经功能障碍。神经发生是卒中后神经元替代、修复和功能恢复的重要内源性机制之一。然而，大脑中大多数新产生的神经元在中风后不久就会死亡。在培养可行的神经元替代的机制中，具有适当的血管生成和新生血管的有利的神经血管生态位是最关键的机制。因此，同时加强神经再生和血管生成的策略将极大地促进中风后神经元的替换和神经功能的恢复。烟酰胺磷酸核糖转移酶(NAMPT)已被证明对缺血性脑损伤具有神经保护作用。NAMPT显著促进人脐静脉内皮细胞增殖、迁移和毛细血管样管形成 细胞培养。然而，在脑缺血的背景下，NAMPT对血管生成的影响还没有得到充分的研究。此外，NAMPT是否增加了神经发生尚不清楚。我们最近发现，NAMPT除了具有急性神经保护作用外，还能促进脑修复和神经血管重塑。值得注意的是，我们发现NAMPT重组蛋白可以跨越血脑屏障(BBB)，还可以改善抗脑缺血的长期功能结果。因此，本项目的目的是在脑缺血的背景下测试NAMPT的新的神经保护/神经恢复功能，以期开发NAMPT作为一种新的、临床相关的缺血性卒中治疗药物。需要检验的假设是，NAMPT通过促进血管生成和神经生成来防止缺血性脑损伤，并改善长期的神经学结果。采用大脑中动脉闭塞(MCAO)方法建立小鼠局灶性脑缺血模型，模拟临床缺血性卒中后脑组织的病理生理变化。提出了以下具体目标：目的1：验证NAMPT可减少脑损伤并改善局灶性脑缺血后长期神经预后的假设。NAMPT对缺血性脑损伤的神经保护作用将首先在脑内特异表达NAMPT的转基因小鼠身上进行测试，然后将使用重组NAMPT蛋白进一步测试其治疗缺血性中风的翻译潜力。评估的终点包括梗死面积和功能结果。目的：验证NAMPT治疗促进脑缺血后脑神经血管重塑的假说，包括促进血管生成和神经再生。将定量分析重组NAMPT蛋白对脑梗塞周围区域卒中后新生血管的影响。NAMPT对缺血性中风后神经干细胞增殖、迁移、分化和神经元替换的影响也将被检测。拟议工作与退伍军人管理局患者护理任务的相关性每年约有11,000名退伍军人因新中风住院，多达80,000名退伍军人是中风幸存者。由于缺乏有效的治疗方法来限制和/或修复中风后破坏性的神经元损伤，中风后肢体残疾的人口继续增长。这项拟议的研究将使NAMPT成为一种新的、临床上可行的治疗策略，以提供急性神经保护和中风后的长期神经恢复。这项研究的成功将促进中风后的康复，提高中风退伍军人的生活质量。

DESCRIPTION (provided by applicant): Stroke is the leading cause of long-term disability in adults in the United States, and no therapy is available to prevent stroke-induced neurological deficits. Neurogenesis is one of the important endogenous mechanisms for neuronal replacement, repair and functional recovery after stroke. However, the majority of newly generated neurons in the brain die soon after stroke. Among the mechanisms that could foster viable neuronal replacement, a favorable neurovascular niche with proper angiogenesis and neovascularization is the most crucial one. Therefore, strategies to enhance both neurogenesis and angiogenesis would greatly improve neuronal replacement and neurological recovery after stroke. Nicotinamide phosphoribosyltransferase (NAMPT) has been proven to be neuroprotective against ischemic brain injury. NAMPT markedly promotes cell proliferation, migration and capillary-like tube formation in human umbilical vein endothelial cell cultures. However, the effect of NAMPT on angiogenesis in the context of cerebral ischemia is under-explored. Furthermore, whether NAMPT increases neurogenesis remains unknown. We have recently found that besides acute neuroprotection, NAMPT also promotes brain repair and neurovascular remodeling. Strikingly, we found that NAMPT recombinant protein can cross the blood brain barrier (BBB) and also improve long-term functional outcomes against cerebral ischemia. Therefore, the objective of this project is to test the novel neuroprotective/ neurorestorative function of NAMPT in the context of cerebral ischemia with a long-term aim to develop NAMPT as a novel, clinically relevant therapeutic agent for ischemic stroke. The hypothesis to be tested is that NAMPT protects against ischemic brain injury and improves long-term neurological outcomes by enhancing angiogenesis and neurogenesis. Focal ischemia will be induced in mice by middle cerebral artery occlusion (MCAO) to mimic the pathophysiological changes in the brain after clinical ischemic stroke. The following specific aims are proposed: Aim 1: Test the hypothesis that NAMPT reduces brain damage and improves long-term neurological outcomes after focal cerebral ischemia. The neuroprotective effect of NAMPT on ischemic brain injury will be first tested in transgenic mice that overexpress NAMPT specifically in the brain, and then its translational potential for the treatment of ischemic stroke will be furher tested using recombinant NAMPT protein. The endpoints for assessment include infarct size and functional outcomes. Aim 2: Test the hypothesis that NAMPT treatment enhances cerebral neurovascular remodeling, including augmented angiogenesis and neurogenesis after cerebral ischemia. The effect of recombinant NAMPT protein on post-stroke neovascularization in peri-infarct brain areas will be quantitatively analyzed. The effect of NAMPT on neural stem cell proliferation, migration, differentiation and neuronal replacement following ischemic stroke will also be examined. Relevance of the proposed work to the VA patient care mission Approximately 11,000 veterans are hospitalized annually with new strokes and up to 80,000 veterans are stroke survivors. The population with post-stroke physical disability continues to grow due to the lack of effective therapies to restrict and/or repair devastating neuronal damage after stroke. The proposed study will develop NAMPT as a novel, clinically feasible therapeutic strategy to offer acute neuroprotection as well as long-term neurological recovery after stroke. The success of this study will enhance post-stroke rehabilitation and improve quality of life for veterans suffering from stroke.