Multiphoton Microscopy for 3-Dimensional Imaging of Lymphocyte Recruitment Into Apolipoprotein-E–Deficient Mouse Carotid Artery

Abstract

Two recent elegant studies have shown that in apolipoprotein-E–deficient mice, the lamina adventitia is a major site of arterial wall inflammation associated with lymphocyte infiltration into atherosclerotic arteries and with formation of adventitial lymphoid-like tissues.1,2 These results suggest that lymphocyte responses in the lamina adventitia may play a crucial role in atherosclerosis development.1,2 However, in both studies, the detection of immune cells within the artery was limited to conventional analysis systems (flow cytometry, immunohistochemistry), which require the removal, disruption, and processing of tissue at defined time points to give a “snapshot” of the immune response to vascular damage in vivo. For evaluation of atherosclerotic processes and their relationship to immune activation, imaging of 3-dimensional structures in intact vascular tissues and functional aspects of the diseased artery (eg, details of the interactions of immune cell with vessel wall structures) are required. A potential solution to this problem is offered by the development of multiphoton laser-scanning microscopy,3 with the ability to penetrate directly into tissues at sufficient depths to image tissues in situ in the absence of significant phototoxicity. By moving the focal point axially, …