Noninvasive strategies of cell-tracking in vivo

In recent years, cell-based therapy, such as adoptive immunotherapy and stem cell restorative therapy, was followed with interest. However, restricted understanding of the metabolic and functional characteristics of the adoptive cells in vivo hinders the clinical translation of these therapeutic cells. For example, the distribution, proliferation, and homing of CAR-T cells in vivo are not clear, so the potential side effect of this cell therapy is unpredictable. In vivo imaging can accurately reveal the physiological status of cells in vivo, including cell activities and migration, which is an important method of life science and clinical research. Currently used cell labeling method, including direct labeling and indirect labeling, offers opportunities to reveal the trace of therapeutic cells in vivo. In this review, we explain the basic methods and application of cell labeling.