Understanding the in vivo behavior of experimental therapeutic cells is fundamental to their successful development and clinical translation. Iodine-124 has the longest half-life (4.2 days) among the clinically used positron emitters. Consequently, this isotope offers the longest possible tracking time for directly labeled cells using positron emission tomography (PET). Herein, we have radiosynthesized and evaluated two iodine-124/fluorescein-based dual PET and fluorescent labeling reagents, namely ¹²⁴I-FIT-Mal and ¹²⁴I-FIT-(PhS)₂Mal for cell surface thiol bioconjugation. ¹²⁴I-FIT-(PhS)₂Mal labeled cells significantly more effectively than ¹²⁴I-FIT-Mal. It conjugated to various cell lines in 22%–62% labeling efficiencies with prolonged iodine-124 retention. ¹²⁴I-FIT-(PhS)₂Mal mainly conjugated on the cell membrane, which was confirmed by high-resolution fluorescence imaging. The migration of ¹²⁴I-FIT-(PhS)₂Mal labeled Jurkat cells was visualized in NSG mice with excellent target-to-background contrast using PET/CT over 7 days. These data demonstrate that ¹²⁴I-FIT-(PhS)₂Mal can dynamically track cell migration in vivo using PET/CT over a clinically relevant time frame.

中文翻译：

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基于碘124的双重正电子发射断层显像和荧光标记试剂，用于体内细胞跟踪。

了解实验性治疗细胞的体内行为是其成功开发和临床翻译的基础。在临床使用的正电子发射器中，碘124的半衰期最长（4.2天）。因此，使用正电子发射断层扫描（PET），这种同位素为直接标记的细胞提供了最长的跟踪时间。在这里，我们已经放射性合成和评估了两种基于碘124 /荧光素的双重PET和荧光标记试剂，即¹²⁴ I-FIT-Mal和¹²⁴ I-FIT-（PhS）₂ Mal用于细胞表面硫醇的生物缀合。¹²⁴ I-FIT-（PhS）₂ Mal标记的细胞比¹²⁴更有效I-FIT-Mal。它以22％–62％的标记效率与各种细胞系结合，并具有延长的碘124保留时间。¹²⁴ I-FIT-（PhS）₂ Mal主要结合在细胞膜上，这已通过高分辨率荧光成像得到了证实。在7天中使用PET / CT在NSG小鼠中观察到¹²⁴ I-FIT-（PhS）₂ Mal标记的Jurkat细胞的迁移，具有优异的靶与背景对比。这些数据表明¹²⁴ I-FIT-（PhS）₂ Mal可以在临床相关的时间范围内使用PET / CT动态跟踪体内细胞迁移。