Non-invasive In Vivo Imaging and Tracking of Dendritic Cells Migration using MR/NIR Dual Modal Contrast Agent

Dendritic cells (DCs) play a key role in immune system as potent antigen-presenting cells (APC), which are uniquely capable of initiating a primary immune response. After DCs capture and process antigen in peripheral tissues,... [ view full abstract ]

Dendritic cells (DCs) play a key role in immune system as potent antigen-presenting cells (APC), which are uniquely capable of initiating a primary immune response. After DCs capture and process antigen in peripheral tissues, they begin to mature and migrate to secondary lymphoid tissues, where they activate naïve T cells. Therefore, DC migration into the draining lymph nodes is critical for T cell priming. Here, we developed a novel magnetic resonance (MR)/near-infrared (NIR) imaging contrast agent, which was synthesized by a facile fluorescent dye coating on magnetic nanoparticles (MNP). The dye-coated MNP was used as a high-performance MR/NIR imaging contrast agent with a high T2 relaxivity (r2) value of approximately 308 mM-1s-1, and NIR fluorescence by biocompatible indocyanine green dye to support non-invasive in vivo tracking of DCs migration into lymph nodes. The impact of the dye-coated MNPs on DC viability and maturation was systematically investigated using MTT assays and FACS analysis. And the labeling effects of DCs with the dye-coated MNPs were investigated in changes on DC phenotype or maturation potential. Importantly, the migration of DCs via lymphatic drainage and homing into the lymph node were monitored through real-time NIR fluorescence and MR imaging. Taken together, this novel MR/NIR contrast agent has potential application as a non-invasive imaging agent for both inducing T cell priming and imaging of DC-based immunotherapy.