Positron Emission Tomography Imaging of Cell Trafficking: A Method of Cell Radiolabeling

Stem cell and chimeric antigen receptor (CAR) T-cell therapies are emerging as promising therapeutics for organ regeneration and as immunotherapy for various cancers. Despite significant progress having been made in these areas, there is still more to be learned to better understand the pharmacokinetics and pharmacodynamics of the administered therapeutic cells in the living system. For noninvasive, in vivo tracking of cells with positron emission tomography (PET), a novel [ Zr]Zr-p-isothiocyanatobenzyl-desferrioxamine ([ Zr]Zr-DBN)-mediated cell radiolabeling method has been developed utilizing Zr (t1/2 78.4 h). The present protocol describes a [ Zr]Zr-DBN-mediated, ready-to-use, radiolabeling synthon for direct radiolabeling of variety of cells, including mesenchymal stem cells, lineage-guided cardiopoietic stem cells, liver regenerating hepatocytes, white blood cells, melanoma cells, and dendritic cells. The developed methodology enables noninvasive PET imaging of cell trafficking for up to 7 days post-administration without affecting the nature or the function of the radiolabeled cells. Additionally, this protocol describes a stepwise method for the radiosynthesis of [ Zr]Zr-DBN, biocompatible formulation of [ Zr]Zr-DBN, preparation of cells for radiolabeling, and finally the radiolabeling of cells with [ Zr]Zr-DBN, including all the intricate details needed for the successful radiolabeling of cells.