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

Abstract

• SPECT and PET are of great importance for in vivo tracking of immune cells. • Cell tracking technique depends on the type of labeled cell and targeted pathology. • Various radiotracers are used in direct and indirect cell labeling methods. • In the indirect labeling methods, applied radiotracers depend on reporter genes. • The most crucial radiotracers, reporter genes and cell labeling methods are described. There is currently great interest in the development of cell-based therapies, particularly those focused on the 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 cells in vivo after administration is vital for the assessment of therapeutic outcomes of immune cell-based therapies both in preclinical research and clinical practice. In this context, imaging techniques, which allow for noninvasive and real-time monitoring of the distribution and long-term viability of the adoptively transferred immune cells in the tissue of interest, are of paramount importance. Among clinically relevant in vivo imaging modalities, the nuclear imaging techniques, comprising planar scintigraphy, SPECT, and PET, are considered to be of pivotal importance to in vivo cell tracking and designing optimal treatment strategies for cell-based therapies. This review paper focuses on nuclear imaging and its role in the evaluation of immune cell-based therapies’ effectiveness - tracking cells and their ability to home to the target tissue. We compare different types of radiotracers, outline various ways of immune cell labeling, and provide the latest examples for the use of nuclear imaging techniques both in preclinical studies and clinical settings.