Annemieke van Wamel PhD, Abstract Co-Author: Nothing to Disclose

Muzaffer Celebi DVM, Abstract Co-Author: Nothing to Disclose

John A. Hossack PhD, Abstract Co-Author: Nothing to Disclose

Joseph M. Backer PhD, Abstract Co-Author: Nothing to Disclose

Klaus Ley MD, Abstract Co-Author: Stockholder, Targeson LLC Research support from Merck, Inc. Research support from Dompe Pharma

Alexander Klibanov PhD, Presenter: Research grant, Koninklijke Philips Electronics NV Stockholder, Targeson, LLC

Non-invasive imaging of tumor vascular endothelium molecular markers may prove crucial for diagnostics and image-guided therapy. Ultrasound contrast agents (USCA) allow fast and convenient molecular imaging in inflammation and angiogenesis. We studied ultrasound molecular imaging with USCA targeted to P- and E-selectins, VCAM-1 and VEGF receptors during tumor growth in a murine model.

C57BL/6 mice (n=4, each condition) received subcutaneous MC38 colon carcinoma cells. Decafluorobutane USCA microbubbles were stabilized with phospholipid monolayer containing biotin-PEG-lipid and PEG-lipid. Biotinylated ligands: anti-VCAM-1 antibody, scVEGF121 or polyacrylamide-sulfoLewisx were attached to USCA via streptavidin. Ultrasound imaging (Vevo 770, 40 MHz, contrast package) was performed after intravenous administration of USCA particles (108/ml, 0.05-0.1 ml saline). After 5 min accumulation/blood clearance period, targeted and residual circulating USCA were imaged in the tumor. USCA was then destroyed by 10 MHz ultrasound; tumor was imaged to establish circulating USCA background signal.

Imaging during contrast bolus confirmed tumor perfusion. Tumor accumulation of nontargeted USCA control was minimal: signal intensity was 3-5±2 (mean±SD) for small (0-5 mm² cross-section), medium (11-20 mm²) or large (31-40 mm²) tumors. Selectin-targeted USCA accumulated well in small tumors (70±10), significantly less (21±5, p<0.025) for medium-size and fell (4±1, p<0.005) for large tumors. VEGF-carrying USCA did not accumulate in small tumors (4±2); signal increased significantly (35±10, p<0.05) for medium and was moderate (20±10) in large tumors. Anti-VCAM-1-USCA accumulation, moderate (20±2) for small tumors, progressed significantly (p<0.005) to 40±2 as tumors grew and fell to 7±2 in largest tumors.

Ultrasound contrast molecular imaging of tumors with USCA targeted to selectins, VCAM-1 or VEGF receptors was achieved. Tumor size-dependent upregulation of these markers on tumor endothelium was observed.

Ultrasound imaging may provide non-invasive diagnostics of tumor vasculature molecular pattern.

van Wamel, A, Celebi, M, Hossack, J, Backer, J, Ley, K, Klibanov, A, Contrast Ultrasound Molecular Imaging of Tumor Vasculature Markers in a Murine Model: Targeting P- and E-selectins, VCAM-1 and VEGF Receptors.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5014617.html