FIGURE 7.

Cell characterization after direct labeling of T-cells with [⁸⁹Zr]Zr-oxine. (A) In vitro proliferation of differently radiolabeled human γδ T-cells demonstrates that with higher amounts of cell label per cell, the capacity to proliferate diminishes. As expansion capacity is crucial for cell-based immunotherapy applications, it is paramount to perform such proliferation assays for sufficiently long times and quantify any differences even if they happen several days after cell labeling. (B) Tumor cell killing assay demonstrates that even γδ T-cells containing radioactivity levels incompatible with further expansion still retain at least part of their tumor killing function if supplied in sufficiently high amounts. Here, the authors reported this using a triple negative breast cancer cell line in vitro by quantifying tumor cell viability 48 h after immune cell addition. Notably, unchelated ⁸⁹Zr supplied to tumor cells did not kill them and served as one of the controls. (C) (left) DNA damage analysis in radiolabeled human γδ T-cells. Representative images of γ-H2AX foci (green) and nuclei (blue); scale bars are 10 μm. (right) Cumulative data from the quantification of γ-H2AX foci per nuclei after radiolabelling. For statistical analysis of all data see Man et al. (2019), from where this figure is reproduced with modification and permission.