Understanding the cellular neurobiology of paediatric stroke and moyamoya disease

中风通常被认为是一种影响老年人的疾病，但它也是儿童的重要疾病——英国每年有数百名儿童受到影响。儿科（儿童）和新生儿（新生儿）中风会导致严重的残疾，包括脑瘫——这是一种终身疾病，每年要花费NHS数百万英镑。虽然成人中风最常见的原因是动脉粥样硬化（由于高胆固醇、吸烟和其他危险因素导致的动脉狭窄），但儿童中风通常是由烟雾病等潜在疾病引起的。在烟雾症中，大脑动脉变窄，导致流向大脑的血液慢性减少。由于我们尚未完全了解的原因，儿童和成人中风的表现、病程和恢复是不同的。我是一名儿科神经外科医生，负责治疗患有烟雾病和中风的儿童。我是多学科神经血管团队的一员，该团队在英国拥有最大的烟雾病和儿科中风病例量。在我接受培训的早期，我承担了一个博士项目，在那里我使用基本的神经科学技术来检查大脑中神经元（神经细胞）和神经胶质细胞（专门的支持细胞）对损伤的反应。我一直对了解大脑中涉及损伤和中风反应的机制很感兴趣，并希望利用这种理解来改善我们对患有这些疾病的儿童的治疗。在这个项目中，我希望将我的临床儿科神经血管实践与我的基础神经科学训练联系起来，在我的研究伙伴的世界知名实验室阐明这些机制。阿特韦尔实验室在研究神经元、神经胶质细胞、脑血流及其紊乱方面拥有丰富的专业知识，使用最先进的技术，包括贴片夹紧、双光子显微镜和一系列转基因动物，允许细胞鉴定。毛细血管是向脑组织输送氧气和营养物质的微小血管。我的研究伙伴发现，这些是由周围被称为“周细胞”的细胞调节的，周细胞部分通过神经胶质细胞对血流和氧气水平的变化做出动态反应。我将使用双光子和共聚焦显微镜研究不同年龄的幼年啮齿动物周细胞对缺血（当大脑没有足够的血液时，例如中风或烟雾）的反应。轴突是在脑细胞之间传递信号的微小“电线”。在儿童时期，最初裸露的轴突逐渐被一种叫做髓磷脂的绝缘物包裹，这对大脑功能的发育是必要的。利用鼠类中风和烟雾症模型，我将使用免疫组织化学标记、钙成像、数学传导模型和电生理学来检查缺血对发育中的大脑轴突、髓鞘形成和Ranvier淋巴结（髓鞘之间的间隙）的影响。我还将描述小胶质细胞与中风相关的特性，小胶质细胞是大脑的免疫细胞，对微环境进行监视，对损伤和细胞死亡做出反应，并修剪不必要的突触。利用转基因啮齿动物的大脑切片，我将用双光子显微镜检查发育中的大脑中小胶质细胞对缺血的反应，并将其与成年人的反应进行比较。作为一名神经外科医生，我可以从手术中接触到脑组织：切除小块的脑组织，以接触血管畸形和肿瘤，否则这些脑组织就会被丢弃。这给了我一个独特的机会，在人类大脑切片上复制啮齿动物实验，并测试其机制是否相同。这些实验将描述儿童大脑对缺血反应的细胞机制，并可能导致新的药物和手术治疗靶点的确定，以减少由儿童中风和烟雾引起的脑损伤，并提高从恢复。

Stroke is often thought of as a disease affecting older adults, but it is a significant condition in children as well - with several hundred affected in the UK annually. Paediatric (children) and neonatal (newborn baby) stroke can lead to significant disabilities including cerebral palsy - a lifelong condition that costs the NHS millions of pounds per year. Although in adults stroke is most often due to atherosclerosis (narrowing of the arteries due to high cholesterol, smoking and other risk factors), in children an underlying condition such as moyamoya disease is often found. In moyamoya, the arteries of the brain narrow, causing a chronic reduction of blood flow to the brain. The presentation, course of, and recovery from stroke are different in children and adults, for reasons we do not yet fully understand.I am a paediatric neurosurgeon who looks after children with moyamoya and stroke. I am part of a multidisciplinary neurovascular team that has the largest caseload of moyamoya and paediatric stroke in the UK. Early in my training, I undertook a PhD project where I used basic neuroscience techniques to examine the response to injury of both neurons (nerve cells) and glial cells (specialized supporting cells) in the brain. I have always been interested in understanding the mechanisms in the brain that are involved in the response to injury and stroke, and hope to use this understanding to improve our treatments for children with these conditions. In this project I wish to link my clinical paediatric neurovascular practice with my basic neuroscience training to elucidate these mechanisms in the world-renowned laboratory of my research partner. The Attwell lab has great expertise in studying neurons, glial cells, and brain blood flow and its disorders, using state of the art techniques including patch-clamping, 2-photon microscopy and a range of transgenic animals allowing cell identification. Capillaries are tiny blood vessels which deliver oxygen and nutrients to brain tissue. My research partner has discovered that these are regulated by surrounding cells called "pericytes" which, in part via glial cells, respond dynamically to changes in blood flow and oxygen levels. I will study the responses of pericytes to ischaemia (when the brain does not get enough blood, e.g. during stroke or in moyamoya) in juvenile rodents of different ages, using 2-photon and confocal microscopy.Axons are the tiny "wires" that send signals between brain cells. During childhood the initially bare axons are progressively wrapped in an insulation called myelin, which is necessary for development of brain function. Employing rodent models of stroke and moyamoya, I will use immunohistochemical labelling, calcium imaging, mathematical conduction modelling and electrophysiology to examine the effect of ischaemia on axons, myelination and the nodes of Ranvier (gaps between myelin) in the developing brain. I will also characterise the stroke-relevant properties of microglia, which are the immune cells of the brain, carrying out surveillance of the microenvironment and responding to injury and cell death, as well as pruning unnecessary synapses. Using brain slices from transgenic rodents I will examine with 2 photon microscopy the responses of microglia to ischaemia in the developing brain and compare them to those of adults.As a neurosurgeon, I have access to brain tissue from operations: small pieces removed to access vascular malformations and tumours, which would otherwise be discarded. This gives me a unique opportunity to replicate rodent experiments on human brain slices and test whether the mechanisms are the same.These experiments will delineate the cellular mechanisms underlying the response of the child's brain to ischaemia, and may lead to the identification of targets for novel drug and surgical therapies to reduce the brain damage caused by, and improve recovery from, paediatric stroke and moyamoya.