Abstract 18399: In vivo targeted Molecular Imaging for Activated Platelets by MRI using USPIO-Fucoidan in Rat Abdominal Aortic Aneuryms
Introduction: P-selectin, expressed on the activated platelets and endothelial cells, is one of the key adhesion molecules that regulate leukocyte trafficking in atherosclerosis. The natural and canonical ligand of selectins is a specific tetrasaccharide structure known as 6-sulfo sialyl Lewis X. Fucoidans refer to a type of polysaccharide which contains L-fucose and sulfate ester groups, mainly derived from brown seaweed, and binds strongly to P-selectin. We assessed the hypothesis that a new MRI contrast agent made of fucoidan conjugated with ultrasmall paramagnetic iron oxide (USPIO) can demonstrate the presence of activated platelets in thrombus of an expanding aneurym.
Methods: Fourteen male Wistar rats were locally infused with elastase. Six days after operation, rats were set on a 4.7T MRI system and scanned before and after the administration of contrast agent. We used T2*-weighted sequences to assess aortic wall enhancement. Three rats (control group) were injected with USPIO-carboxyl methyl dextran (CMD) which was used as a non specific contrast agent, and 12 rats with USPIO-CMD-Fucoidan. Signal to noise ratio and contrast to noise ratio were calculated on the aorta in both groups. Histological sections were compared with MR imaging sections.
Results: Twelve over 14 rats developed an aneurysm. In the group injected with USPIO-CMD-Fucoidan (10 rats with aneurysm and 2 without), all rats except the two rats without aneurysm showed multiple signal attenuation areas along the aortic wall within 30–45 minutes after injection. Conversely, none of the rats injected with USPIO-CMD showed signal attenuation. In Conclusions, we present a new contrast agent based on USPIO and fucoidan, with capabilities to depict quickly and specifically activated platelets. Such contrast agent might be useful to non-invasively detect thrombus.
- © 2010 by American Heart Association, Inc.