脑组织液流动的磁共振成像示踪及其机制研究

Although the brain extracellular space (ECS) comprised 20% of the whole brain volume, its effects on the brain function and brain diseases are still unclear. This situation is mainly because of the limitation of the previous developed measuring techniques and devices. An in vivo study for ISF flow in the scale of whole brain is the key to solve the above problem. We therefore developed a tracer-based measuring technique by using MRI. The brain ISF was found to flow in a physiologically partitioned channel system, and each area is characterized with its ECS tortuosity (λ) and local clearance rate (K '); The metabolism level and the water channel protein (AQP4) played an important role in regulating the speed of the brain ISF flow. Based on the above findings, in current study, we are going to finish mapping of the brain ISF drainage territories in the whole rat brain ISF, and compared the map from the AQP4 gene knockout rats. The micro morphology and molecular biological basis for the partitioned flow system will be studied by using the fluorescence confocal imaging and molecular biology techniques, including PCR and western blot. A full interpretation for the physiological property of brain ISF flow and its mechanism will provide a theoretical basis for the investigation of the local brain drug delivery via brain ECS.

由于以往测量技术的限制，占脑容积20%的脑细胞外间隙（ECS）及其内组织液（ISF）在认知与脑病中的作用与机制尚未阐明，脑ISF在全脑范围内的分布引流规律研究是解决上述问题的关键。申请人应用所发明的磁共振分子探针技术，实现了ISF在脑内引流的三维动态成像，发现鼠脑ISF呈分区引流，且各分区ECS迂曲度(λ)及清除率(K')不同，局部代谢水平与水通道蛋白含量（AQP4）在调节ISF流动特性中发挥重要作用。本研究拟在前期工作基础上，测绘并比较正常鼠与AQP4基因敲除鼠全脑ISF引流图谱，比较各引流区ECS的扩散参数，应用荧光标记成像技术明确各引流区代谢水平与形态学特征，辅以PCR、western blot技术，进一步明确AQP4对脑ISF引流的作用方式及规律。本研究将阐明脑组织引流的规律，并从细胞与分子水平阐明分区引流机制，研究结果为经脑ECS途径的脑病治疗的探索研究提供理论基础与依据。

本研究应用本课题组发明的专利技术（脑细胞外间隙测量法），发现脑细胞外间隙内的类淋巴组织液（ISF）引流的分区特征，发现了胶质细胞对细胞外间隙（ECS）内水溶性小分子药物转运的调控规律与机制。基于上述科学发现，提出经ECS途径的新型脑病给药治疗方法，较美军从哈佛大学购买的专利技术更加高效、低毒、安全，并获批国际发明专利。在证实组织液引流分区的结构基础后，提出脑分区稳态新理论，以封面故事发表于Prog Neurobiol.，目前，科学发现和新技术、新理论已应用于脑发育、AD、脑病新药研发、脑肿瘤、AI新模型研究、中医中药、航天医学等前沿科学领域。