The characteristics of capillary remodeling in cerebellar neurodegenerative diseases revealed through layered imaging and stereoscopic analysis

Neurodegenerative diseases refer to a group of clinical conditions characterized by progressive neuronal loss, resulting in impaired brain structural integrity and functional abnormalities. These diseases can lead to widespread cerebrovascular remodeling; however, the spatial remodeling features of capillaries with diameters ≤ 10 μm remain poorly understood, particularly with regard to changes in the relationship between neurons and capillaries. In this study, we first developed a double-fluorescent transgenic mouse model of cerebellar neurodegenerative disease (CBND), the PCKO ^Tomato Vessel ^Green mouse, in which Purkinje cells (PCs) in the cerebellum express red fluorescent protein, while the cerebrovascular system in the cerebellum expresses green fluorescent protein (with no differentiation between arteries and veins). Subsequently, we employed whole-brain clearing combined with the Amira/Imaris system to conduct three-dimensional layered imaging and computational analysis of the cerebrovascular network in both adult control and PCKO ^Tomato Vessel ^Green mice. A total of 181744 PCs and cerebrovascular vessels with a total length of 17.7363 meters, 266175 segments, and a total volume of 0.5314 mm³ were analyzed. Compared to the Control mice, PCKO ^Tomato Vessel ^Green mice exhibited a 93% reduction in count of PCs, a 97% reduction in total volume of PCs, a 69% reduction in cerebellar volume, a 58% decrease in total cerebrovascular vessel length, and a 52% decrease in total cerebrovascular vascular volume. Depth analysis of vessels with diameters ≤ 10 μm revealed a 55%, 58%, 58%, and 52% reduction in capillary volume, chord length, curved length, and tortuosity, respectively, with no statistical differences in node count or φ and θ directional values. Further volume fraction (VF) analysis revealed a 59% increase in capillary-cerebellum VF, while the PC-vessel VF, PC-capillary VF, and PC-noncapillary VF decreased by 95%, 95%, and 96%, respectively. Additionally, the shortest distance between PCs and cerebrovascular vessels decreased by 58%, while vessel-cerebellum VF and noncapillary-cerebellum VF showed no statistical differences. Our results indicated that while capillaries with diameters ≤ 10 μm were significantly lost, their vascular topology remained stable, with the distance between PCs and cerebrovascular vessels decreasing from 16 μm to 7 μm. This remodeling process is central to the pathogenesis of cerebrovascular changes in CBND. Furthermore, the increase in capillary-cerebellum VF and the decrease in PC-vessel VF may serve as biological markers for the early diagnosis of CBND. These findings provide a foundation for the early diagnosis and development of targeted therapies for CBND. Short abstract Cerebrovascular remodeling caused by neurodegenerative diseases can be used for early diagnosis, but its characteristics are unclear. Our research group first constructed PCKO ^Tomato Vessel ^Green mice with cerebellar neurodegenerative disease, and then adopted whole cerebellar transparency combined with Amira/Imaris system. A total of 181744 Purkinje cells with a total length of 17.7363 m, a total number of 266175 segments and a total volume of 0.5314 mm ³ were analyzed by three-dimensional stratified imaging and computational analysis. A total of 3.15 TB of data revealed that capillaries with diameters ≤ 10 μm were significantly lost although the vascular topology remained stable. Additionally, the distance between Purkinje cells and blood vessels decreased from 16 μm to 7 μm, identifying this as a central feature of neurovascular remodeling in cerebellar neurodegenerative disease. The increase of capillary-cerebellum volume fraction and the decrease of Purkinje cell-vessel volume fraction can be used as biological markers for the early diagnosis of neurodegenerative diseases.