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

基本信息

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
项目类别：
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&apos s Disease Alzheimer&apos s disease model Alzheimer&apos 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

项目摘要

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，这些机制尚不清楚。在AD/ADRD鼠标模型中，有几种降低的原因在不同水平的微血管网络中运行的血流和调节功能障碍已是确定。在过表达突变基因的小鼠中，导致AD和具有遗传和心血管风险的小鼠神经变性的因素，脑血流减少，神经血管耦合障碍，通过周细胞缩小毛细血管流明，被捕的白血细胞的毛细血管流量已经报告。但是，由于当前量化微血管流动的方法是对网络中单个微血管中发生的事件不敏感（即它们测量平均流量许多船只因此错过了诸如毛细管摊位之类的事件）或无法评估网络流和灌注变化由微血管事件引起（即它们一次测量太少，以量化上游和下游流量或区域灌注因毛细管失速而变化）。流量和灌注下降和异质性由于这种事件而引起的可能在神经退行性疾病的进展中起重要作用，因为网络微域具有持续或重复的网络灌注时期 - “寡头微弹药” - 可能是用于脑细胞功能障碍，淀粉样蛋白积累和微吸收性的热点。流量的测量需要在连接网络上的每个微型分裂中的速度来研究瞬时微血管事件会影响网络血流和组织灌注。该建议旨在开发和测试范式 - 转移方法转向2光（2p和3p）激发荧光成像以达到速度和深度在新皮层中〜300微血管中轻松测量流动所需的穿透性或深处〜50 小鼠皮质下白质（WM）。产生飞秒激光脉冲的自适应兴奋源（AES） “按需”与快速的3D栅格扫描同步，并且仅在血液的地方进行射击脉冲船只居住。因为可以传递到大脑的最大激光功率是限制速率的，AES限制了 2p/3p兴奋性脉冲仅针对血管，从而测量了速度，直径和信号的测量来自所有微血管的其他细胞类型特异性荧光标签在皮质中的300x300x300 µm3体积中或在深WM中的200x200x100 µm3体积（100 Hz体积成像为1x1x10 µm3素体尺寸）（AIM 1）。这种创新的成像能力将用于探索所选的集体影响和因果关系 AD小鼠模型皮质中CBF绝对性的分子和细胞机制，并测试假设寡量微量流量是淀粉样蛋白沉积的部位（AIM 2）。 AES成像的能力探索小鼠深WM中的网络流量和灌注能够检查通用的影响与WM微血管网络上与AD/ADRD相关的心血管危险因素可提供新颖洞察全球灌注量如何在微观级别诱导WM损伤（AIM 3）。