Preliminary results: Imaging of in situ labeled tumor-associated macrophages with magnetic particle imaging

Tumor-associated macrophages (TAMs) are thought to be protumoral, enhancing and contributing to cancer progression. The presence of TAMs has been correlated with the metastasis of tumor cells and the inhibition of the antitumoral immune responses mediated by T cells. In this brief paper, we used Magnetic Particle Imaging (MPI) to detect passively targeted TAMs homing to a breast cancer model. TAMs were passively targeted using PEG-coated Magnetic Nanoparticles (PEG-MNPs). Escalating doses of PEG-MNPs were tested to evaluate TAM uptake at different time points. An MPI signal was detected in liver and tumor for all the groups except at the lowest dose. A novel quantitation workflow has also been proposed to calculate the quantity of iron inside the different tissues.