Abstract 5543: Carbon Nanotubes Allow Fluorescence Imaging of Macrophages in Mouse Carotid Atherosclerosis
Introduction: Macrophages are important imaging targets for characterizing and monitoring atherosclerotic lesions. Carbon nanotubes show promising properties as vehicles for cellular imaging and therapy.
Methods: In vitro: mouse macrophage cells (RAW) were incubated for 24 hours with single-walled carbon nanotubes (NT; diameter 1.2nm, concentration 2.5mg/L) labeled with a near infrared fluorophore Cy5.5. NT uptake was examined using confocal microscopy. In vivo: FVB mice (N=6) had a macrophage-rich carotid atherosclerotic lesion created through high fat diet for 4 weeks and diabetes induction by 5 daily injections of streptozotocin, followed 2 weeks later by ligation of the left carotid artery (N=4) or sham operation (N=2). Two weeks post operation, all mice were given NT-Cy5.5 (8nmol of Cy5.5) via tail vein and scanned serially over 48 hours by in-vivo fluorescent imaging (CRI, Woburn, MA). Then both in situ and ex vivo imaging were performed followed by histological evaluation.
Results: NT were taken up by 92% of macrophages in vitro. In vivo imaging showed limited carotid signal, however, both in situ and ex vivo imaging showed high signal from the ligated left carotid arteries (upper figure⇓, graph). No accumulation of NT was seen in non-ligated right carotid arteries or sham-operated left carotid arteries (left carotid - yellow arrows, right carotid - red arrows). Immunofluorescence microscopy of the ligated carotid lesions (lower figure⇓) showed colocalization of NT-Cy5.5 and macrophages labeled with Mac3/FITC.
Conclusions: NT accumulate in atherosclerotic macrophages in vivo and provide a multi-functional platform for plaque imaging and potentially therapy.
This research has received full or partial funding support from the American Heart Association, Western States Affiliate (California, Nevada & Utah).