Research Article

Quantification of Nanoparticle Enhancement in Polarized Breast Tumor Macrophage Deposits by Spatial Analysis of MRI and Histological Iron Contrast Using Computer Vision

Figure 2

Spatial quantification of endogenous and contrast-enhanced macrophage deposits by iron histology. Paraffin-embedded sections from control (−USPIO) and iron nanoparticle-injected (+USPIO) tumors. (a) Prussian blue iron staining, (b) F4/80 macrophage immunofluorescence, and (c) CD31 vascular immunofluorescence were performed in the same sections to demonstrate the colocalization of iron deposits with infiltrating macrophages in vascular areas of the tumor microenvironment. Histological fields from (d) control and (e) iron nanoparticle-injected mice showing deposits of Prussian blue iron+ macrophages localized in infiltrative border regions in discrete clusters. Black borders are regions of interest drawn automatically around deposits of cells according to iron status. Expansion shows iron+ macrophages in the deposit regions. (f) Number of iron deposits (clusters) per tumor cross section in control (−USPIO) and nanoparticle-injected (+USPIO) mice (mean ± SEM shown, tumors/group, , two-tailed unpaired Student’s -test). (g) Number of iron+ macrophages per deposit, and (h) size of each of the deposits measured over the whole Paraffin-embedded tumor cross sections stained by Prussian blue (mean ± SEM shown, −USPIO total clusters/group, +USPIO total clusters/group, n.s. ). Scale bar is shown for all images.