Abstract 355: In vivo Assessment of Novel Magnetic Microbubbles Targeted to P-selectin for Inflammatory Molecular Imaging in High-shear Flow
Background: Contrast-enhanced ultrasound imaging (CEU) using microbubbles targeted to the endothelial cell inflammatory marker has a great potential for detection of vascular disease. However, the achievement of this technique at the artery conditions of high-shear flow is currently difficult due to the limited binding. We, therefore, hypothesized that a “novel” microbubbles targeted to the endothelial cell adhesion molecule P-selectin, which was capable of both antibody-mediated targeting and magnetic field (MF)-guided, has sufficient and specific adhesion to evaluate endothelial cell inflammatory marker in high-shear flow.
Methods: The biotinylated anti-mice P-selectin (MBpm) or isotype control antibody (MBim) was attached to the biotinylated lipid-microbubbles (LM) (or fluorescent LM) via a magnetic streptavidin bridge. 18 mice were equally divided into test group with local injection of cytokines interleukin-1β and TNF-α and control group with saline. CEU and Fluorescent microscopy of the abdominal aorta were performed in both groups at 10 minutes after intravenous injection of either MBpm or MBim in random at the 30 minutes interval. MF-guided was used in the first 3 minutes after the injection. Video intensity (VI) and fluorescen intensity (FI) from the microbubbles targeted to P-selectin were measured. Abdominal aortas were harvested for immunohistochemial examination.
Results: No matter MBim or MBpm, the attachment to P-selectin was not detected visually by both imaging techniques in all mice if without MF-guided. As expected, only in test group mice and with MF-guided, the microbubbles targeted to P-selectin were visualized by both exams during intravenous MBpm injection, and the VI and FI in the setting were significantly higher (6.3–13.6 folds and 8.2–16.9 folds, respectively) than those of the other settings (P<0.05). The expression of P-selectin on examined aorta was confirmed by immunohistochemisty.
Conclusions: The data demonstrate that the magnetic microbubbles targeted to the endothelial P-selectin have excellent and specific adhesion efficacy in high-shear flow, allowing for the detecting of arterial inflammation and other endothelial responses noninvasively with ultrasound imaging.