Abstract 5467: Magnetic Resonance Imaging Of Renal Ischemia Reperfusion Injury Using Microparticles Of Iron Oxide Targeting VCAM-1
Introduction: Ischemia/reperfusion injury (IRI) is an important cause of tissue damage in vascular syndromes of the heart, brain and kidney. Sensitive tools to image ischemic injury non-invasively are lacking. We hypothesized that antibody-conjugated microparticles of iron oxide (MPIO) targeting VCAM-1, would enable molecular magnetic resonance imaging (MRI) of endothelial activation in mouse renal IRI.
Methods & Results: MPIO (1.0 μm) were conjugated to a monoclonal antibody against vascular cell adhesion molecule-1 (VCAM-MPIO). In-vitro, VCAM-MPIO bound, in a dose-dependent manner, to tumor necrosis factor (TNF)-α stimulated sEND-1 endothelial cells, as quantified by light microscopy (R2 = 0.88, P = 0.03). VCAM-1 expression was quantified using real time reverse-transcriptase (RT) PCR (10.0-fold increase versus control; P < 0.01) and confirmed by western blot. In male C57BL/6 mice (n = 6) the left renal pedicle was cross-clamped to induce IRI (30 minutes ischemia followed by 12 hour reperfusion). VCAM-MPIO, injected intravenously in vivo, were quantifiable using ex-vivo MRI. VCAM-MPIO binding to endothelium was 2.5-fold greater than control IgG-MPIO (P < 0.01) in ischemic kidneys. No significant difference was found between VCAM-MPIO and control IgG-MPIO in non-ischemic kidneys.
Conclusion: (1) VCAM-MPIO binding to activated endothelium gives a quantitative measure of target. (2) In a mouse model of renal IRI in-vivo, VCAM-MPIO bound specifically and under flow conditions. (3) Retained MPIO were readily quantifiable by MRI. (4) This provides a platform for non-invasive detection of IRI in the kidney and other organs.