In vivo imaging of lymph node migration of MNP- and (111) in-labeled dendritic cells in a transgenic mouse model of breast cancer (MMTV-Ras)

PURPOSE: The authors present a protocol for the in vivo evaluation, using different imaging techniques, of lymph node (LN) homing of tumor-specific dendritic cells (DCs) in a murine breast cancer model. PROCEDURES: Bone marrow DCs were labeled with paramagnetic nanoparticles (MNPs) or (111)In-oxine. Antigen loading was performed using tumor lysate. Mature DCs were injected into the footpads of transgenic tumor-bearing mice (MMTV-Ras) and DC migration was tracked by magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT). Ex vivo analyses were performed to validate the imaging data. RESULTS: DC labeling, both with MNPs and with (111)In-oxine, did not affect DC phenotype or functionality. MRI and SPECT allowed the detection of iron and (111)In in both axillary and popliteal LNs. Immunohistochemistry and γ-counting revealed the presence of DCs in LNs. CONCLUSIONS: MRI and SPECT imaging, by allowing in vivo dynamic monitoring of DC migration, could further the development and optimization of efficient anti-cancer vaccines.