Figure 2: SWNTs accumulate within phagocytes in the atherosclerotic plaque.

a, Blood decay curve of ⁸⁹Zr-radiolabelled-SWNTs. The mean t_1/2 was calculated as 1.64hr (R² = 0.96; n = minimum 4 biologically independent animals per time point). b, Quantitative biodistribution studies 7 days after intravenous administration of ⁸⁹Zr-SWNTs reveal that SWNTs primarily accumulate in organs with high macrophage content, such as the spleen and liver (n = 8 biologically independent animals). c,d, Flow cytometry analyses of homogenized organs confirm the trend for enhanced uptake by organs of the reticuloendothelial system (c), and reveals that SWNT accumulation is largely restricted to the macrophage-rich plaque, as compared to the less disease-prone descending aorta (n = minimum 3 biologically independent animals) (d). *p < 0.05 by unpaired two-tailed t-test in (c). *p < 0.05, **p < 0.01, ****p < 0.0001 by one-way ANOVA with a Tukey post-hoc test in (d). e-g, Following 4 weeks of weekly SWNT administration, SWNTs specifically accumulate within Ly-6C^hi monocytes and macrophages in the atherosclerotic aorta, while SWNT detection is low in other vascular cells (n = 4 biologically independent animals) (e). ***p < 0.001, ****p < 0.0001 one-way ANOVA with a Tukey post-hoc test. Lesional macrophage (red) and SWNT (green) co-localization is confirmed by confocal images of the aortic sinus (co-localized regions indicated by arrows). Scale bar, 50 μm (right panel, 25 μm). (f). Enhanced uptake is observed by Ly-6C^hi monocytes in the aorta compared to the spleen, suggesting that SWNTs may be efficiently delivered to the diseased artery by inflammatory monocytes (n = 4 biologically independent animals) (g). *p < 0.05 by unpaired two-tailed t-test. Data in f are representative of 4 independent experiments. For all graphs, data are expressed as the mean and s.e.m.