Detection of macrophage activity in atherosclerosis in vivo using multichannel, high-resolution laser scanning fluorescence microscopy

Ashvin N. Pande; Rainer Kohler; Elena Aikawa; Ralph Weissleder; Farouc Jaffer

doi:10.1117/1.2186337

1 March 2006 Detection of macrophage activity in atherosclerosis in vivo using multichannel, high-resolution laser scanning fluorescence microscopy

Ashvin N. Pande, Rainer Kohler, Elena Aikawa, Ralph Weissleder, Farouc Jaffer

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Journal of Biomedical Optics, Vol. 11, Issue 2, 021009 (March 2006). https://doi.org/10.1117/1.2186337

Abstract

Molecular and cellular mechanisms of atherogenesis and its treatment are largely being unraveled by in vitro techniques. We describe methodology to directly image macrophage cell activity in vivo in a murine model of atherosclerosis using laser scanning fluorescence microscopy (LSFM) and a macrophage-targeted, near-infrared fluorescent (NIRF) magnetofluorescent nanoparticle (MFNP). Atherosclerotic apolipoprotein E deficient (apoE -/-) mice (n=10) are injected with MFNP or 0.9% saline, and wild-type mice (n=4) are injected with MFNP as additional controls. After 24 h, common carotid arteries are surgically exposed and prepared for LSFM. Multichannel LSFM of MFNP-enhanced carotid atheroma (5×5-µm in-plane resolution) shows a strong focal NIRF signal, with a plaque target-to-background ratio of 3.9±1.8. Minimal NIRF signal is observed in control mice. Spectrally resolved indocyanine green (ICG) fluorescence angiograms confirm the intravascular location of atheroma. On ex vivo fluorescence reflectance imaging, greater NIRF plaque signal is seen in apoE -/- MFNP mice compared to controls (p<0.01). The NIRF signal correlates well with immunostained macrophages, both by stained surface area (r=0.77) and macrophage number (r=0.86). The validated experimental methodology thus establishes a platform for investigating macrophage activity in atherosclerosis in vivo, and has implications for the detection of clinical vulnerable plaques.

©(2006) Society of Photo-Optical Instrumentation Engineers (SPIE)

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Ashvin N. Pande, Rainer Kohler, Elena Aikawa, Ralph Weissleder, and Farouc Jaffer "Detection of macrophage activity in atherosclerosis in vivo using multichannel, high-resolution laser scanning fluorescence microscopy," Journal of Biomedical Optics 11(2), 021009 (1 March 2006). https://doi.org/10.1117/1.2186337

Published: 1 March 2006

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