In Vivo Imaging of the Mouse Neurovascular Unit Under Chronic Cerebral Hypoperfusion

• Published in: Stroke (1970) Vol. 45; no. 12; pp. 3698 - 3703
• Main Authors: Yata, Kenichiro, Nishimura, Yuhei, Unekawa, Miyuki, Tomita, Yutaka, Suzuki, Norihiro, Tanaka, Toshio, Mizoguchi, Akira, Tomimoto, Hidekazu
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD American Heart Association, Inc 01.12.2014; Lippincott Williams & Wilkins
• Subjects: Animals; Biological and medical sciences; Brain - pathology; Brain Ischemia - pathology; Green Fluorescent Proteins - genetics; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Imaging, Three-Dimensional - methods; Male; Medical sciences; Mice; Mice, Transgenic; Microscopy, Confocal - methods; Nervous system (semeiology, syndromes); Neuroimaging - methods; Neurology; Vascular diseases and vascular malformations of the nervous system; Pericyte; Stroke; Nervous system diseases; Two photon microscopy; Leukocyte; pericytes; Rodentia; Cardiovascular disease; Astrocyte; Cerebral disorder; Encephalon; Vascular disease; Microcirculation; Vertebrata; Chronic; Mammalia; Mouse; Animal; Central nervous system disease; leukocytes; microscopy, fluorescence, multiphoton; astrocytes; Fluorescence microscopy; Cerebrovascular disease; microcirculation
• ISSN: 0039-2499; 1524-4628
• DOI: 10.1161/STROKEAHA.114.005891

BACKGROUND AND PURPOSE—Proper brain function is maintained by an integrated system called the neurovascular unit (NVU) comprised cellular and acellular elements. Although the individual features of specific neurovascular components are understood, it is unknown how they respond to ischemic stress as a functional unit. Therefore, we established an in vivo imaging method and clarified the NVU response to chronic cerebral hypoperfusion. METHODS—Green mice (b-act-EGFP) with SR101 plasma labeling were used in this experiment. A closed cranial window was made over the left somatosensory cortex. To mimic chronic cerebral hypoperfusion, mice were subjected to bilateral common carotid artery stenosis operations using microcoils. In vivo real-time imaging was performed using 2-photon laser-scanning microscopy during the preoperative period, and after 1 day and 1 and 2 weeks of bilateral common carotid artery stenosis or sham operations. RESULTS—Our method allowed 3-dimensional observation of most of the components of the NVU, as well as dynamic capillary microcirculation. Under chronic cerebral hypoperfusion, we did not detect any structural changes of each cellular component in the NVU; however, impairment of microcirculation was detected over a prolonged period. In the pial small arteries and veins, rolling and adhesion of leukocyte were detected, more prominently in the latter. In the deep cortical capillaries, flow stagnation because of leukocyte plugging was frequently observed. CONCLUSIONS—We established an in vivo imaging method for real-time visualization of the NVU. It seems that under chronic cerebral hypoperfusion, leukocyte activation has a critical role in microcirculation disturbance.