Visualizing myocardial inflammation in a rat model of type 4 cardiorenal syndrome by dual-modality molecular imaging

Type 4 cardiorenal syndrome (CRS) is a life-threatening world health problem in which chronic kidney disease leads to progressive cardiovascular disease. In type 4 CRS, cardiac inflammation is an excellent target for both detection and therapy; however, this progression was underestimated by previous studies due to the lack of effective detection methods. To noninvasively visualize cardiac inflammation and monitor therapeutic efficacy of anti-inflammatory treatment in type 4 CRS, we here synthesized a dual-modality magneto-fluorescent nanoparticle (MNP) by combining ultrasmall superparamagnetic iron oxide nanoparticle and Rhodamine B for both magnetic resonance imaging (MRI) and optical imaging. This dual-functional MNP exhibited excellent performance such as high r2 relaxivity coefficient (283.4 mM-1 s-1), high magnetism (96.7 emu/g iron) and a near neutral surface charge to minimize the reticuloendothelial system uptake. In vivo cardiac MRI showed significant negative contrast in the type 4 CRS rats, and the signal intensity on optical imaging was significantly higher in the type 4 CRS group compared with sham-operated and drug-treated groups. The specific targeting profile of MNPs to monocyte-macrophages was proven by histopathological analysis. Taken together, we demonstrate that this dual-modality strategy is feasible for noninvasively assessing myocardial inflammation and monitoring therapeutic efficacy in type 4 CRS.