Nyúl-Tóth Ádám, Tarantini Stefano, DelFavero Jordan, Yan Feng, Balasubramanian Priya, Yabluchanskiy Andriy, Ahire Chetan, Kiss Tamas, Csipo Tamas, Lipecz Agnes, Farkas Attila E, Wilhelm Imola, Krizbai István A, Tang Qinggong, Csiszar Anna, Ungvari Zoltan
Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center For Geroscience and Healthy Aging, Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma.
International Training Program in Geroscience, Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, Hungary.
Am J Physiol Heart Circ Physiol. 2021 Apr 1;320(4):H1370-H1392. doi: 10.1152/ajpheart.00709.2020. Epub 2021 Feb 5.
Age-related blood-brain barrier (BBB) disruption and cerebromicrovascular rarefaction contribute importantly to the pathogenesis of both vascular cognitive impairment and dementia (VCID) and Alzheimer's disease (AD). Recent advances in geroscience research enable development of novel interventions to reverse age-related alterations of the cerebral microcirculation for prevention of VCID and AD. To facilitate this research, there is an urgent need for sensitive and easy-to-adapt imaging methods that enable longitudinal assessment of changes in BBB permeability and brain capillarization in aged mice and that could be used in vivo to evaluate treatment efficiency. To enable longitudinal assessment of changes in BBB permeability in aged mice equipped with a chronic cranial window, we adapted and optimized two different intravital two-photon imaging approaches. By assessing relative fluorescence changes over the baseline within a volume of brain tissue, after qualitative image subtraction of the brain microvasculature, we confirmed that, in 24-mo-old C57BL/6J mice, cumulative permeability of the microvessels to fluorescent tracers of different molecular masses (0.3 to 40 kDa) is significantly increased compared with that of 5-mo-old mice. Real-time recording of vessel cross-sections showed that apparent solute permeability of single microvessels is significantly increased in aged mice vs. young mice. Cortical capillary density, assessed both by intravital two-photon microscopy and optical coherence tomography was also decreased in aged mice vs. young mice. The presented methods have been optimized for longitudinal (over the period of 36 wk) in vivo assessment of cerebromicrovascular health in preclinical geroscience research. Methods are presented for longitudinal detection of age-related increase in blood-brain barrier permeability and microvascular rarefaction in the mouse cerebral cortex by intravital two-photon microscopy and optical coherence tomography.
与年龄相关的血脑屏障（BBB）破坏和脑微血管稀疏在血管性认知障碍和痴呆（VCID）以及阿尔茨海默病（AD）的发病机制中起着重要作用。老年科学研究的最新进展使得开发新的干预措施成为可能，以逆转与年龄相关的脑微循环改变，从而预防VCID和AD。为了促进这项研究，迫切需要灵敏且易于应用的成像方法，能够纵向评估老年小鼠血脑屏障通透性和脑毛细血管化的变化，并可用于体内评估治疗效果。为了能够纵向评估配备慢性颅骨窗口的老年小鼠血脑屏障通透性的变化，我们采用并优化了两种不同的活体双光子成像方法。通过在脑微血管定性图像相减后，评估脑组织体积内相对于基线的相对荧光变化，我们证实，在24月龄的C57BL/6J小鼠中，与5月龄小鼠相比，微血管对不同分子量（0.3至40 kDa）荧光示踪剂的累积通透性显著增加。血管横截面的实时记录显示，老年小鼠单个微血管的表观溶质通透性相对于年轻小鼠也显著增加。通过活体双光子显微镜和光学相干断层扫描评估的皮质毛细血管密度在老年小鼠中也低于年轻小鼠。所提出的方法已针对临床前老年科学研究中脑微血管健康的纵向（36周期间）体内评估进行了优化。本文介绍了通过活体双光子显微镜和光学相干断层扫描纵向检测小鼠大脑皮质中与年龄相关的血脑屏障通透性增加和微血管稀疏的方法。
