Measuring impairment of extracellular solute transport in Alzheimer's disease

项目概要/摘要 脑的细胞外空间（ECS）由高度互连的狭窄通道网络组成， 宽度为10-80 nm的片状结构。血管周围的空间与血管相连， ECS和充当用于将溶质运输通过实质并运输至在表面处的CSF的管道。 大脑向组织输送营养物、清除有毒蛋白质聚集体和向靶点输送治疗剂 需要通过ECS运输，并且在运输的速率和机制方面存在相当大的不确定性。 体内运输具体而言，血管周围组织中溶质转运的速率、方向或调节 空间很好理解。最近，我们证明了多光子荧光恢复后， 引入ECS的外源荧光团的光漂白（MP-FRAP）可用于直接 测量体内脑实质深处的溶质转运速率。在此进行的实验 将采用这种技术来测量小鼠脑中血管周围溶质转运的速率和方向， 从而解决关于这些空间的生理学的基本问题。在阿尔茨海默病（AD）中， 淀粉样斑块形成于实质和血管周围，引起广泛的结构变化 和周围神经胶质的功能。这些变化的后果溶质的运输在 血管周围空间在很大程度上仍是未知的，我们将利用AD模型小鼠来确定Aβ沉积是否 损害血管周围溶质运动。希望这些实验将导致一个 定量和充分证实的了解血管周围的细胞外运输在大脑中，和 提出了增强内源性清除机制和改善治疗递送的方法。

Project summary/abstract The extracellular space (ECS) of the brain consists of a highly interconnected network of narrow tunnel and sheet-like structures with width of 10-80 nm. Perivascular spaces surrounding blood vessels connect with the ECS and act as conduits for transport of solutes throughout the parenchyma and to the CSF at the surface of the brain. Nutrient delivery to tissues, clearance of toxic protein aggregates and therapeutic delivery to targets require transport through the ECS and considerable uncertainty exists regarding the rates and mechanisms of transport in vivo. Specifically, neither the rate, direction or regulation of solute transport in the perivascular spaces are well understood. Recently, we demonstrated that multiphoton fluorescence recovery after photobleaching (MP-FRAP) of exogenous fluorophores introduced into the ECS can be used to directly measure solute transport rates deep within the brain parenchyma in vivo. Experiments to be performed here will adapt this technique to measure the rates and direction of perivascular solute transport in mouse brain and thereby resolve basic questions regarding the physiology of these spaces. In Alzheimer’s disease (AD), amyloid plaques form in the parenchyma and around blood vessels, causing extensive changes in structure and function of the surrounding glia. The consequences of these changes for transport of solutes in the perivascular space remain largely unknown and we will utilize AD model mice to determine if deposition of Aβ around vessels impairs perivascular solute movement. It is hoped that these experiments will lead to a quantitative and well substantiated understanding of perivascular extracellular transport in the brain, and suggest approaches for enhancing endogenous clearance mechanisms and improving therapeutic delivery.