Optimizing Zirconium-89 labeling for chimeric antigen receptor T cell PET imaging by comparing desferrioxamine and...

This study aimed to optimize Zirconium-89 (⁸⁹Zr) labeling strategies for in vivo tracking of chimeric antigen receptor (CAR)-T cell migration using positron emission tomography (PET). The performances of the [⁸⁹Zr]Zr-p-isothiocyanatobenzyl-desferrioxamine (DFO) and [⁸⁹Zr]Zr-oxine methods were compared to identify the most suitable chelator and activity concentration for cell labeling. CD19 CAR-Jurkat T cells were labeled with each [⁸⁹Zr]Zr complex at different activity concentrations following optimization of the chelator amount and incubation time, and were then evaluated for cell viability, proliferation, and function over seven days. The refined synthesis procedures achieved radiochemical purities greater than 95%. Labeling efficiencies were 84.2 ± 5.4% for [⁸⁹Zr]Zr-DFO and 43.7 ± 1.2% for [⁸⁹Zr]Zr-oxine. [⁸⁹Zr]Zr-DFO-labeled cells demonstrated high viability (94.2 ± 1.1%) and maintained 82% of baseline proliferation capacity over seven days, whereas [⁸⁹Zr]Zr-oxine-labeled cells showed reduced viability (77.3 ± 7.8%) and a markedly impaired proliferation capacity, retaining only 7% of baseline. These results indicate that [⁸⁹Zr]Zr-DFO provided superior labeling efficiency and cell preservation compared with [⁸⁹Zr]Zr-oxine, supporting its potential use for PET-based tracking of CAR-T cells in cell therapy applications.