Date Published: April 1, 2018
Publisher: JKL International LLC
Author(s): Lin-Yuan Zhang, Pan Lin, Jiaji Pan, Yuanyuan Ma, Zhenyu Wei, Lu Jiang, Liping Wang, Yaying Song, Yongting Wang, Zhijun Zhang, Kunlin Jin, Qian Wang, Guo-Yuan Yang.
Elucidating the normal structure and distribution of cerebral vascular system is fundamental for understanding its function. However, studies on visualization and whole-brain quantification of vasculature with cellular resolution are limited. Here, we explored the structure of vasculature at the whole-brain level using the newly developed CLARITY technique. Adult male C57BL/6J mice undergoing transient middle cerebral artery occlusion and Tie2-RFP transgenic mice were used. Whole mouse brains were extracted for CLARITY processing. Immunostaining was performed to label vessels. Customized MATLAB code was used for image processing and quantification. Three-dimensional images were visualized using the Vaa3D software. Our results showed that whole mouse brain became transparent using the CLARITY method. Three-dimensional imaging and visualization of vasculature were achieved at the whole-brain level with a 1-μm voxel resolution. The quantitative results showed that the fractional vascular volume was 0.018 ± 0.004 mm3 per mm3, the normalized vascular length was 0.44 ± 0.04 m per mm3, and the mean diameter of the microvessels was 4.25 ± 0.08 μm. Furthermore, a decrease in the fractional vascular volume and a decrease in the normalized vascular length were found in the penumbra of ischemic mice compared to controls (p < 0.05). In conclusion, CLARITY provides a novel approach for mapping vasculature in the whole mouse brain at cellular resolution. CLARITY-optimized algorithms facilitate the assessment of structural change in vasculature after brain injury.
In our study, we mapped the vasculature in a whole mouse brain at cellular resolution using the CLARTY technique. Furthermore, we established optimized algorithms for vascular extraction and quantification that were compatible with CLARITY imaging. This imaging and analysis system provides a powerful tool for further evaluating structural the alterations of whole-brain vasculature in rodent disease models.