Abstract 5812: Label-free 3D En-face Imaging Platform For Atherosclerosis With Lipid Molecular Analysis Using Coherent Anti-stokes Raman Scattering Microscopy
Introduction Current methodology of assessing plaque vulnerability is limited due to poor resolution and lack of chemical information. Coherent anti-Stokes Raman scattering (CARS) spectroscopy can monitor the contrast of vibration frequencies among molecules. The abundance of C-H bonds in atherosclerotic lipids permits to visualize them with 300 nm lateral resolution. We report a new label-free imaging platform for atherosclerotic lesions based on CARS spectrum analysis.
Methods and results Human atherosclerotic carotid arteries after endarterectomy were imaged by CARS (n=2). The en-face CARS images from lumen to deep intima clearly showed foam cells with intracellular lipid droplets in superficial intima. On the other hand, enlarged lipid crystal structures (i.e. droplet, pin, plate) were observed in deep intima. To investigate the progression of atherosclerosis at early stage, a time-course experiment was conducted using apolipoprotein E knock-out atherosclerotic mice from 2–12 weeks (n=23). Whole aorta was longitudinally opened and en-face imaged. After 6 weeks, the number of lipid droplets was significantly increased (p=0.015) and foam cells were observed. In 8 weeks, lipid crystallized structures were imaged in lesions. Chemical information of the imaged lipid structures were directly identified by explicit difference in their multiplex CARS spectra without any imaging probes or isotopes.
Conclusions This CARS platform allows label-free en-face imaging in sub-micron scale and simultaneous chemical profiling of lipid structures in both human and mouse plaques. We expect that this platform can be a powerful diagnosis and prognosis tool for atherosclerosis.