Nuclear imaging for immune cell tracking in vivo – Comparison of various cell labeling methods and their application

There is currently great interest in the development of cell-based therapies, particularly those focused onthe idea of exploiting systemically administered immune cells for therapeutic purposes in cancer (e.g.,CAR-T and CAR-NK cells). The ability to monitor the fate of cellsin vivoafter administration is vital forthe assessment of therapeutic outcomes of immune cell-based therapies both in preclinical researchand clinical practice. In this context, imaging techniques, which allow for noninvasive and real-time mon-itoring of the distribution and long-term viability of the adoptively transferred immune cells in the tissueof interest, are of paramount importance. Among clinically relevantin vivoimaging modalities, thenuclear imaging techniques, comprising planar scintigraphy, SPECT, and PET, are considered to be of piv-otal importance toin vivocell tracking and designing optimal treatment strategies for cell-based thera-pies. This review paper focuses on nuclear imaging and its role in the evaluation of immune cell-basedtherapies’ effectiveness - tracking cells and their ability to home to the target tissue. We compare differ-ent types of radiotracers, outline various ways of immune cell labeling, and provide the latest examplesfor the use of nuclear imaging techniques both in preclinical studies and clinical settings.