Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748, Garching, Germany.
Department of Clinical Radiology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany.
Eur J Nucl Med Mol Imaging. 2022 Nov;49(13):4338-4357. doi: 10.1007/s00259-022-05896-5. Epub 2022 Jul 19.
Modern neuroimaging lacks the tools necessary for whole-brain, anatomically dense neuronal damage screening. An ideal approach would include unbiased histopathologic identification of aging and neurodegenerative disease.
We report the postmortem application of multiscale X-ray phase-contrast computed tomography (X-PCI-CT) for the label-free and dissection-free organ-level to intracellular-level 3D visualization of distinct single neurons and glia. In deep neuronal populations in the brain of aged wild-type and of 3xTgAD mice (a triply-transgenic model of Alzheimer's disease), we quantified intracellular hyperdensity, a manifestation of aging or neurodegeneration.
In 3xTgAD mice, the observed hyperdensity was identified as amyloid-β and hyper-phosphorylated tau protein deposits with calcium and iron involvement, by correlating the X-PCI-CT data to immunohistochemistry, X-ray fluorescence microscopy, high-field MRI, and TEM. As a proof-of-concept, X-PCI-CT was used to analyze hippocampal and cortical brain regions of 3xTgAD mice treated with LY379268, selective agonist of group II metabotropic glutamate receptors (mGlu2/3 receptors). Chronic pharmacologic activation of mGlu2/3 receptors significantly reduced the hyperdensity particle load in the ventral cortical regions of 3xTgAD mice, suggesting a neuroprotective effect with locoregional efficacy.
This multiscale micro-to-nano 3D imaging method based on X-PCI-CT enabled identification and quantification of cellular and sub-cellular aging and neurodegeneration in deep neuronal and glial cell populations in a transgenic model of Alzheimer's disease. This approach quantified the localized and intracellular neuroprotective effects of pharmacological activation of mGlu2/3 receptors.
现代神经影像学缺乏用于全脑、解剖密集型神经元损伤筛查的必要工具。理想的方法应包括对衰老和神经退行性疾病进行无偏倚的组织病理学鉴定。
我们报告了多尺度 X 射线相衬计算机断层扫描（X-PCI-CT）在死后应用的情况，该方法可用于对不同的单个神经元和神经胶质进行无标记和无解剖的器官级到细胞内级 3D 可视化。在老年野生型和 3xTgAD 小鼠（阿尔茨海默病的三重转基因模型）大脑的深部神经元群体中，我们量化了细胞内高密度，这是衰老或神经退行性变的表现。
在 3xTgAD 小鼠中，通过将 X-PCI-CT 数据与免疫组织化学、X 射线荧光显微镜、高场 MRI 和 TEM 相关联，观察到的高密度被鉴定为淀粉样β和过度磷酸化的 tau 蛋白沉积物，涉及钙和铁。作为概念验证，X-PCI-CT 用于分析 3xTgAD 小鼠海马和皮质脑区，这些小鼠接受了选择性 II 型代谢型谷氨酸受体（mGlu2/3 受体）激动剂 LY379268 的治疗。mGlu2/3 受体的慢性药理学激活显著降低了 3xTgAD 小鼠腹侧皮质区域的高密度颗粒负荷，表明具有局部疗效的神经保护作用。
这种基于 X-PCI-CT 的多尺度微到纳米 3D 成像方法使我们能够鉴定和量化阿尔茨海默病转基因模型中深部神经元和神经胶质细胞群体中的细胞和亚细胞衰老和神经退行性变。该方法量化了 mGlu2/3 受体药理学激活的局部和细胞内神经保护作用。
