Distribution of nanoparticles in rats 3-hour after intravenous injection of FITC-NP.

(A), Representative light (left) and fluorescence (right) stereomicrographs of whole hearts 3 hours after intravenous injection of FITC-NP. Scale bar: 5 mm (upper). Fluorescence microscopic images of the cross sections of the IR hearts treated with FITC-NP. Cardiomyocytes are identified by anti-troponin T antibody (red) and nuclei by DAPI (blue). Merged image shows colocalization of troponin T and FITC-NP. Scale bar: 100 nm (lower). (B), Representative light (upper) and fluorescence (lower) stereomicrographs of cross-sections of the IR hearts 3-hour after intravenous injection of vehicle, FITC alone, or FITC-NP. In the light images, hearts were double-stained with Evans blue and TTC to determine the area at risk. Scale bar: 5 mm. (C), Quantification of FITC fluorescence intensity in AAR and non-ischemic area 3-hour after intravenous injection of vehicle, FITC alone, or FITC-NP. N = 4 each. Data are compared using one-way ANOVA followed by Bonferroni’s multiple comparison tests. (D), Fluorescence stereomicrographs of the IR hearts from rats co-treated with Evans blue dye and FITC-NP. Evans blue (red) and FITC (green) fluorescence signals were co-localized in IR myocardium. Scale bar: 5 mm. Close correlation between the intensity of FITC and Evans blue. Thirty ROIs were placed on the fluorescence images of heart sections per animal (n = 4) at random. Values of mean fluorescence intensity of both FITC and Evans blue were determined in the same ROI (n = 120). Pearson’s correlation was used to investigate relationships between the fluorescence intensity of FITC and Evans blue. (E), Flow cytometric histograms of CD11b-positive leukocytes in the IR hearts and the blood 24-hour after intravenous injection of FITC-NP. Cells were labeled with anti-CD11b antibodies. White indicates control fluorescence in cells derived from uninjected animals. Green indicates fluorescence in cells derived from FITC-NP injected mice. Right graphs show mean fluorescence intensity (MFI) in CD11b-positive leukocytes in ischemic myocardium (upper) and blood (lower). Data are mean±SEM (n = 5 per group). Data are compared using unpaired t tests.