Multimodality imaging demonstrates trafficking of liposomes preferentially to ischemic myocardium.

INTRODUCTION: Nanoparticles may serve as a promising means to deliver novel therapeutics to the myocardium following myocardial infarction. We sought to determine whether lipid-based liposomal nanoparticles can be shown through different imaging modalities to specifically target injured myocardium following intravenous injection in an ischemia-reperfusion murine myocardial infarction model.

METHODS: Mice underwent ischemia-reperfusion surgery and then either received tail-vein injection with gadolinium- and fluorescent-labeled liposomes or no injection (control). The hearts were harvested 24h later and underwent T1 and T2-weighted ex vivo imaging using a 7 Tesla Bruker magnet. The hearts were then sectioned for immunohistochemistry and optical fluorescent imaging.

RESULTS: The mean size of the liposomes was 100nm. T1-weighted signal intensity was significantly increased in the ischemic vs. the non-ischemic myocardium for mice that received liposomes compared with control. Optical imaging demonstrated significant fluorescence within the infarct area for the liposome group compared with control (163±31% vs. 13±14%, p=0.001) and fluorescent microscopy confirmed the presence of liposomes within the ischemic myocardium.

CONCLUSIONS: Liposomes traffic to the heart and preferentially home to regions of myocardial injury, enabling improved diagnosis of myocardial injury and could serve as a vehicle for drug delivery.