High-speed imaging of cortical and white matter microvascular flow in AD/ADRD models

AD/ADRD 模型中皮质和白质微血管血流的高速成像

• 批准号: 10523289
• 负责人: Costantino Iadecola
• 金额: $ 229.65万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-15 至 2025-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10523289
• 关键词: 3-Dimensional; Address; Affect; Alzheimer' s Disease; Alzheimer' s disease model; Alzheimer' s disease related dementia; Amyloid; Amyloid deposition; Behavior; Blood; Blood Cells; Blood Vessels; Blood capillaries; Blood flow; Brain; Budgets; Caliber; Cerebrovascular Circulation; Cerebrovascular Disorders; Disease; Disease Progression; Event; Fire - disasters; Fluorescence; Functional disorder; Genes; Genetic Risk; Health; Heterogeneity; Image; Imaging Device; Impaired cognition; Impairment; Individual; Knowledge; Label; Lasers; Lead; Leukocytes; Link; Location; Measurement; Measures; Mediating; Microcirculation; Microscopy; Modeling; Molecular; Mus; Neocortex; Nerve Degeneration; Neurodegenerative Disorders; Pathogenicity; Pathology; Penetration; Perfusion; Pericytes; Photons; Physiologic pulse; Play; Production; Regional Perfusion; Regulation; Reporting; Risk; Risk Factors; Role; Sampling; Scanning; Severities; Signal Transduction; Site; Source; Speed; Stream; Surface; Symptoms; System; Testing; Theft; Time; Tissues; Visualization; White Matter Disease; Work; amyloid pathology; blood flow measurement; brain cell; cardiovascular risk factor; cell type; cerebrovascular; constriction; fluorescence imaging; fluorophore; hypoperfusion; imaging approach; imaging capabilities; imaging system; in vivo imaging; innovation; insight; interest; mouse model; mutant; neurovascular; neurovascular coupling; neutrophil; novel; overexpression; relating to nervous system; three photon microscopy; vascular risk factor; white matter; white matter damage

Summary: High-speed imaging of cortical and white matter microvascular flow in AD/ADRD models Although vascular risk factors and cerebrovascular dysfunction are known to be pathogenically linked to AD/ADRD, the mechanisms are not well understood. In AD/ADRD mouse models, several causes of decreased blood flow and regulatory dysfunction that operate at different levels of the microvascular network have been identified. In mice overexpressing mutant genes that cause AD and in mice with genetic and cardiovascular risk factors for neurodegeneration, decreases in cerebral blood flow, impairment of neurovascular coupling, narrowing of capillary lumens by pericytes, and stalling of capillary flow by arrested white blood cells have been reported. However, much remains unknown because current approaches for quantifying microvascular flow are insensitive to events occurring in individual microvessels in a network (i.e. they measure averaged flow across many vessels so miss an event like a capillary stall) or are unable to evaluate network flow and perfusion changes caused by microvascular events (i.e. they measure too few vessels at a time to quantify up- and down-stream flow or regional perfusion changes due to a capillary stall). Flow and perfusion decreases and heterogeneity arising from such events could play an important role in the progression of neurodegenerative disease, as network microdomains with persistent or repeated epochs of network hypoperfusion – “oligemic micropockets” – may be hotspots for brain cell dysfunction, amyloid accumulation, and microinfarcts. Measurement of flow speed in every microvessel across a connected network is needed to investigate how transient microvascular events impact network blood flow and tissue perfusion. This proposal seeks to develop and test a paradigm- shifting approach to 2- and 3-photon (2P and 3P) excited fluorescence imaging to achieve the speed and depth penetration necessary to simultaneously measure flow in ~300 microvessels in the neocortex or ~50 in the deep subcortical white matter (WM) of mice. An adaptive excitation source (AES) generating femtosecond laser pulses “on demand” is synchronized with fast 3D raster scanning and is programmed to fire pulses only where blood vessels reside. Because the maximum laser power that can be delivered to the brain is rate limiting, AES restricts 2P/3P excitation pulses only to blood vessels enabling measurement of the speed, diameter, and signals from additional cell type-specific fluorescent labels from all microvessels in a 300x300x300 µm3 volume in the cortex or in a 200x200x100 µm3 volume in the deep WM (100 Hz volume imaging with 1x1x10 µm3 voxel size) (Aim 1). This innovative imaging capability will be used to explore the collective impact and causal links between selected molecular and cellular mechanisms of CBF abnormality in the cortex of AD mouse models, as well as to test the hypothesis that oligemic micropockets are sites of amyloid deposition (Aim 2). The ability of AES imaging to explore network flow and perfusion in the deep WM of mice enables the examination of the impact of genetic and cardiovascular risk factors associated with AD/ADRD on the WM microvascular network to provide novel insights into how global hypoperfusion induces WM damage at the microscale level (Aim 3).

摘要：AD/ADRD 模型中皮质和白质微血管血流的高速成像 尽管已知血管危险因素和脑血管功能障碍与 AD/ADRD，其机制尚不清楚。在 AD/ADRD 小鼠模型中，AD/ADRD 小鼠模型中 在微血管网络不同水平上运作的血流和调节功能障碍已被 确定。在过度表达导致 AD 的突变基因的小鼠以及具有遗传和心血管风险的小鼠中 神经退行性变的因素，脑血流量减少，神经血管耦合受损， 周细胞使毛细血管管腔变窄，以及白细胞停滞使毛细血管血流停滞。 报道称。然而，还有很多未知之处，因为目前量化微血管流量的方法还很有限。 对网络中各个微血管中发生的事件不敏感（即，它们测量跨过的平均流量 许多血管因此错过了毛细血管失速等事件，或者无法评估网络流量和灌注变化 由微血管事件引起（即一次测量的血管太少，无法量化上游和下游 由于毛细血管失速导致的流量或区域灌注变化）。流量和灌注减少以及不均匀性 由此类事件引起的可能在神经退行性疾病的进展中发挥重要作用，因为 具有持续或重复的网络低灌注时期的网络微域——“寡血微口袋” – 可能是脑细胞功能障碍、淀粉样蛋白积累和微梗死的热点。流量测量 需要通过连接网络的每个微血管的速度来研究瞬时微血管如何 事件影响网络血流和组织灌注。该提案旨在开发和测试一个范例 - 将方法转变为 2 光子和 3 光子（2P 和 3P）激发荧光成像，以实现速度和深度 同时测量新皮质约 300 个微血管或深层约 50 个微血管的流量所需的穿透力 小鼠皮质下白质（WM）。产生飞秒激光脉冲的自适应激励源 (AES) “按需”与快速 3D 光栅扫描同步，并被编程为仅在血液出现的地方发射脉冲 船只驻留。由于可以传送到大脑的最大激光功率是有速率限制的，所以 AES 限制了 仅向血管发送 2P/3P 激励脉冲，从而能够测量血管的速度、直径和信号 来自皮质中 300x300x300 µm3 体积中所有微血管的附加细胞类型特异性荧光标记 或者在深 WM 中的 200x200x100 µm3 体积中（100 Hz 体积成像，体素大小为 1x1x10 µm3）（目标 1）。 这种创新的成像能力将用于探索所选项目之间的集体影响和因果关系 AD小鼠模型皮质CBF异常的分子和细胞机制，以及测试 假设少微囊是淀粉样蛋白沉积的部位（目标 2）。 AES 成像的能力 探索小鼠深层 WM 中的网络流动和灌注能够检查遗传的影响 以及与 WM 微血管网络上的 AD/ADRD 相关的心血管危险因素，以提供新的 深入了解整体灌注不足如何在微观层面诱发 WM 损伤（目标 3）。