Site-targeted imaging enhancement of viable myocardium after ischemia-reperfusion by a novel nano-scale ultrasound contrast agent: a vivo study

Objective To prepare a kind of lipid nanoparticle ultrasound contrast agents with the ability to target to viable myocardium for diagnosis. Methods The agent was a biotinylated, fluorescent-labelled, lipid-coated, liquid perfluorocarbon emulsion. Physico-chemical properties of the agent were measured, including size distribution, Zeta Potential, concentration and so on. Ischemia-reperfusion models were created in rats, and then exposed to biotinylated anti-MCP-1 monoclonal antibody, rhodamine avidin and biotinylated, FITC-labelled nanoparticles, respectively. Echocardiography was taken before and after injection. Frozen sections of their hearts were observed under fluorescence microscope. Results The particle diameter, zeta potential and concentration of lipid nanoparticles were (172.30±52.06)nm, (-33.10±6.50)mV and (2.28±0.46)×1011/ml, respectively. From the short-axis view, the myocardium under endocardium of anterior wall was enhanced obviously. While myocardium of other walls were still. The lipid nanoparticles located in the myocardium of anterior wall and gave out bright green and red fluorescence under fluorescence microscope, while neither lipid nanoparticles nor fluorescence were found in other sites of ventricular myocardium. Conclusions The viable myocardium can be targeted and acoustically enhanced by the self-made nano-scale ultrasound contrast agent. This new agent has potential to improve sensitivity and specificity for noninvasive identifying viable myocardium. Key words: Ultrasound contrast agents; Nano-scale; Perfluorocarbon; Viable myocardium