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

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.