Abstract 5761: Ultrasound and Magnetic Resonance Imaging: The Role of Microbubbles and Gadolinium-Labeled Microbubbles in Imaging after Balloon Angioplasty
BACKGROUND: Perfluorocarbon exposed sonicated dextrose albumin (PESDA) microbubbles bind injured vascular endothelium and can be non-invasively imaged. Scavenger receptors are; regulators of innate immune responses, expressed on endothelial cells, and upregulated during vascular injury and repair. These receptors are involved in cell signaling, initiation and progression of atherosclerosis and restenosis. In this study, the nature of PESDA and Gadolinium (Gd)-labeled PESDA binding in angioplastied aortic tissue was investigated.
METHODS: Abdominal aortic tissues in Sprague-Dawley (SD) rats (n=4 –5 per group) were analyzed by: 1) Real-time RT-PCR for the expression of scavenger receptors [SRA, CD36, oxidized LDL receptor (OLDLr), SRB-1, SRA, Toll-2, and 4] that may bind PESDA. Ultrasound (U/S), 7T magnetic resonance imaging (MRI) and scanning electron microscopy (SEM) were utilized to evaluate PESDA binding.
RESULTS & CONCLUSIONS: Real-time RT-PCR demonstrated an up-regulation in the mRNA of CD36, OLDLr, SRA, Toll-2 and 4, SRB-1, at 4, 48, and 72 hours as compared to non-injured thoracic aortic tissue. The extent of mRNA upregulation was positively correlated to the extent of balloon injury. SEM confirmed the presence of bound microbubbles at the sites of balloon injury as determined by U/S and MRI. Therefore, these studies demonstrated:
Scavenger receptor expression correlates with PESDA binding after angioplasty;
PESDA and Gd-PESDA bind to angioplastied tissue and may serve as a surrogate marker of innate inflammation; and,
Microbubbles can potentially be used to non-invasively image early vascular pathophysiologic processes with U/S or MRI.
This research has received full or partial funding support from the American Heart Association, AHA Midwest Affiliate (Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, South Dakato & Wisconsin).