Mapping Extracellular pH of Gliomas in Presence of Superparamagnetic Nanoparticles: Towards Imaging the Distribution of Drug-Containing Nanoparticles and Their Curative Effect on the Tumor Microenvironment

Figure 4

Comparison of maps for (a) RG2 glioma and (b) 9L gliosarcoma before and after infusion of SPIO-NPs in rats that underwent coinfusion of TmDOTP⁵⁻ and probenecid. In both (a) and (b), (i) and (ii) represent the maps before and after SPIO-NPs infusion, respectively, while (iii) depicts a detailed ROI analysis. See Figure 1 for details of the ROI mask. In (a), the inside the more aggressive RG2 glioma was typically lower than in the healthy/nontumor tissue, but diffuse acidification was observed well-beyond the MRI-defined tumor boundary. Thus the slowly increased as the distance from the tumor core increased. In (b), the inside the less aggressive 9L gliosarcoma was also lower than in the healthy/nontumor tissue, but the acidification did not extend beyond the MRI-defined tumor boundary, before and after infusion of SPIO-NPs. See Figure S4 for a comparison of regional dependence on the method used for inhibition of renal clearance (renal ligation versus probenecid).

(a)

(b)