NOVEL INSIGHTS INTO CEREBRAL ISCHEMIC PATHOPHYSIOLOGY IN HUMANS

通过我们的中风自然史研究(协议号01-N-0007；ClinicalTrials.gov No.NCT00009243)我们对2700多名参与者进行了研究，以便更多地了解中风，并获得可能作为未来研究基础的信息。这一方案使我们能够1)建立脑血管疾病(中风)患者的登记；2)表征急性中风和短暂性脑缺血发作(TIA)的自然病史(即脑血流中断，导致短时间内出现中风症状)；以及3)评估数据，为未来的研究产生想法。 核磁共振通过提供高度敏感和特异的疾病标志物，提高了我们诊断急性中风患者并对其进行分层的能力。基于成像的中风表型增加了客观性，但它们仍然是对中风所启动的复杂生物系统的严重过度简单化。下一代测序在吞吐量和速度方面都有了前所未有的改进，为探索使用急性MRI分层的中风患者的复杂生物学反应提供了机会。基于导致成像异常的生物学将反映在外周血中差异基因表达和微小RNA的前提下，下一代测序将被用于识别和表征与成像表型相关的生物系统。一种系统生物学方法将被开发出来，以更好地描述中风，并有望更好地区分那些我们可以预期对干预措施有良好反应的患者和那些有进一步恶化风险的患者。通过与NINR的合作，我们正在开发一种对血液中单个单核细胞进行测序的方法，以更好地表征急性免疫反应和可能影响结果的因素。 基于成像的中风预后和治疗反应的预测指标对于成像生物标记物在药物开发中的实用性和有效性是必要的。有用的模型是那些可以区分注定要获得良好结果和糟糕结果的患者，那些接受了有效治疗的患者和没有接受治疗的患者，以及治疗应答者和无应答者。我们正在研究几个预测模型。这些预测模型可能对急性疗法的开发、选择和使用有用。我们发现，病变体积从治疗前的DWI到治疗后的FLAIR的变化可以区分接受有效的急性卒中治疗(即静脉注射tPA)的患者的预后好坏。因此，病变体积的变化可能是卒中治疗进展中临床反应的一个有用的标志。 在机械取栓术治疗大血管闭塞性卒中的多项阳性试验之后，在我们中心接受这种治疗的患者人数显著增加。利用核磁共振成像，我们观察到血栓摘除后继发的损伤，这可能是一种可能可以预防的再灌注损伤。我们目前正在使用这个项目中收集的数据来研究成像标记物，这项研究是通过一个名为卫士的前瞻性子研究进行的。这项工作的目标是前瞻性地研究继发性损伤的影像标记物，以开发一项试验，以在栓子切除之前保护大脑，并为无法完成栓子切除的患者提供保护。通过与麦加弗恩实验室的合作，我们已经确定了一种策略，以减少因髓细胞渗透而导致的大量水流入对组织造成的继发性损伤。我们已经确定了与栓子切除后再灌注和出血转化相关的水肿程度。麦加文团队发现了一种抗黏附分子的治疗方法。我们目前正处于设计一项治疗栓子摘除术后患者的试验的早期阶段。 在过去的五年中，我们中心的溶栓治疗率也大幅上升，我们认为部分原因是NINDS卒中团队和MRI诊断方法使更高水平的监测成为可能。大约每2名接受治疗的患者中就有1人可能被归类为轻度中风，每4人中就有1人的症状可能不是致残性的。回顾分析表明，溶栓治疗的成像靶点在有和没有致残缺陷的患者中没有区别。最近一项针对轻微中风的临床试验失败在该领域引起了争议，一些从业者认为，使用tPA治疗轻微(非致残性)中风几乎没有什么收获，反而有很大的风险。我们认为，核磁共振可能是选择那些可能受益的患者的最佳方式。该计划和领域趋于均衡的趋势表明，需要进行一项试验，以测试使用MRI选择的轻微中风患者的溶栓剂。我们已经前瞻性地收集了关于轻微中风的数据，以支持试验的设计，并正在进行分析。NINR对循环单核细胞单细胞下降序列的研究为与轻度中风恢复或恶化相关的生物学机制提供了一些见解。 作为卒中分支的一部分，人们对血管认知障碍和白质疾病非常感兴趣，最初是由神经血管脑成像单位(NVBI)发起的。调查人员继续获取数据和图像，以研究白质疾病和血脑屏障中断。为此目的启动了一项新的议定书(Pi Clinton Wright)，然而，大流行导致所有与研究相关的活动暂停。作为该项目的一部分，工作继续通过收集的数据来研究中风对脑白质疾病和认知障碍的影响。

Through our Natural History of Stroke study (Protocol No. 01-N-0007; Clinicaltrials.gov No. NCT00009243) we have studied greater than 2,700 participants in order to learn more about stroke and obtain information that may serve as the basis for future investigations. This protocol has allowed us to 1) establish a registry of patients with cerebrovascular disease (stroke); 2) characterize the natural history of acute stroke and transient ischemic attacks (TIA) an interruption of blood flow to the brain that causes stroke symptoms for a short period of time); and 3) evaluate the data to generate ideas for future studies. MRI has improved our ability to diagnose and stratify patients with acute stroke by providing highly sensitive and specific markers of the disease. Imaging based phenotypes of stroke increase objectivity, however they remain a gross oversimplification of the complex biological system set in motion by a stroke. Next generation sequencing, with unprecedented improvement in throughput and speed, provides an opportunity to probe the complex biological response to stroke in patients stratified using acute MRI. Based on the premise that the biology responsible for the imaging abnormalities will be reflected in differential gene expression and micro RNA in peripheral blood, next generation sequencing will be used to identify and characterize the biological systems relevant to the imaging phenotype. A systems biology approach will be developed to better describe stroke, and hopefully, better differentiate those patients in who we can expect a favorable response to an intervention, from those at risk of further deterioration. Through collaboration with NINR, we are developing an approach to sequencing single monocytes in the blood to better characterize the acute immune response and factors that may contributed to outcome. Imaging based predictors of stroke outcome and response to therapy are necessary for the utility and validation of imaging biomarkers in drug development. Useful models are those that can distinguish patients destined for good outcomes versus poor outcomes, those who received effective therapy from those who did not, and treatment responders from non-responders. We are investigating several predictive models. These prediction models may be useful for the development, selection and use of acute therapies. We found that change in lesion volume from pre-treatment DWI to post-treatment FLAIR can discriminate between patients destined for good and poor outcomes when treated with effective acute stroke therapy, i.e., intravenous tPA. Thus, lesion volume change may be a useful marker of clinical response in the stroke therapy development. Following multiple positive trials of mechanical embolectomy to treat large vessel occlusion stroke, a significant increase in the population of patients receiving this therapy at our centers has occurred. Using MRI, we have observed injury secondary to embolectomy that may be a form of reperfusion injury that could possibly be prevented. We are currently studying the imaging markers using data collected in this project through a prospective sub-study termed GUARDS. The goal of this effort is to prospectively study an imaging marker of secondary injury to develop a trial to protect the brain prior to embolectomy and for patients in whom embolectomy can not be accomplished. Through collaboration with the McGavern lab, we have identified a strategy to reduce secondary injury to tissue caused by a massive influx of water secondary to myeloid cell infiltration. We have characterized the degree of edema associated with post-embolectomy reperfusion and hamorrhagic transformation. The McGavern team has discovered an anti-adhesion molecule therapeutic approach. We are currently in the early phase of designing a trial to treat patients post embolectomy. Over the past five years, the rate of thrombolytic therapy has also increased dramatically at our center, we believe owing in part to a higher level of surveillance made possible by the NINDS Stroke Team and MRI diagnostic approach. Approximately 1 in 2 patients treated may be categorized as minor stroke, and 1 in 4 have symptoms that may not be disabling. Retrospective analysis suggests that imaging targets for thrombolytic therapy do not differ between those with and without disabling deficits. The recent failure of a clinical trial for minor stroke has created controversy in the field, with some practitioners arguing little is to be gained, and much to be risked, by treating minor (non-disabling) stroke with tPA. We believe MRI may be the best way to select those patients who could benefit. The trend toward equipoise in the program and field argues for a trial to test a thrombolytic in minor stroke selected using MRI. We have prospectively collected data on minor stroke to support the design of a trial and are in the process of analysis. The work with NINR on single cell drop seq of circulating monocytes provides some insight into the biological mechanisms relevant to recovery or worsening in minor stroke. As part of the Stroke Branch, there is significant interested in vascular cognitive impairment and white matter disease, originally initiated but the Neuro Vascular Brain Imaging Unit (NVBI). Investigators continue to access data and images to study white matter disease and BBB disruption. A new protocol was initiated for this purpose (PI Clinton Wright), however the pandemic caused a pause in all study related activity. Work continues to study the impact of stroke on white matter disease and cognitive impairment through data collected as part of this project.