Gallium-68 PET tracking reveals where nanoerythrosomes travel in rats

Researchers have shown that nanoerythrosomes, laboratory-made mimics of extracellular vesicles built from donated human blood, can be radiolabeled with gallium-68 and followed through the bodies of healthy rats using positron emission tomography (PET). The study, published in EJNMMI Radiopharmacy and Chemistry, reports a workable two-step labeling route and reveals distinct patterns of uptake in several tissues compared with control compounds.

Nanoerythrosomes (NanoEs) are described by the authors as extracellular vesicle mimetics suitable for large-scale manufacturing using donated human blood. Because they can serve as carriers for both disease treatment and diagnostics, understanding where they travel after injection is a key step toward any clinical use. To map that whole-body behavior, the team turned to PET imaging, which allows biodistribution to be tracked in living animals rather than inferred from tissue samples alone.

The labeling strategy relied on the [68Ga]Ga-tris(8-hydroxyquinoline) complex. Synthesis of the labeled NanoEs took 77 ± 9 minutes (n = 4) and achieved a decay-corrected radiochemical yield of 35 ± 20% (n = 4). The product was purified using size exclusion chromatography and analyzed with thin layer chromatography before any animal work began.

For the imaging experiment, the radiolabeled NanoEs were administered to healthy Sprague-Dawley rats, followed by 60-minute PET scans. After imaging, tissues were collected so that radioactivity could be quantified directly. The biodistribution of the labeled NanoEs was compared against three control groups: rats given [68Ga]GaCl3 alone, rats given the free [68Ga]Ga-tris(8-hydroxyquinoline) complex, and rats given NanoEs labeled with [68Ga]GaCl3.

The comparison produced a clear result: [68Ga]Ga-tris(8-hydroxyquinoline)-NanoEs showed significantly higher uptake in the liver, the pancreas, and blood cells than any of the control groups. This pattern suggests that the labeled vesicle mimetics behave differently in circulation from either the free radiotracer or the alternative gallium-labeled particles, and that the tris(8-hydroxyquinoline) labeling approach captures biodistribution features that the other strategies do not.

The authors conclude that it is feasible to radiolabel NanoEs as a novel type of biocompatible nanomaterial with [68Ga]Ga-tris(8-hydroxyquinoline), and that the significant differences observed in PET imaging and biodistribution across several tissues represent a step forward in developing NanoE-based delivery platforms for PET imaging and therapeutic purposes.

The reported radiochemical yield, while workable, also varied considerably between preparations. Nevertheless, the work demonstrates that gallium-68 labeling can serve as a practical tool for monitoring these blood-derived nanocarriers in vivo, providing a foundation for future studies of how such delivery platforms behave in the body.

Subject of Research: Gallium-68 radiolabeling and PET imaging of nanoerythrosome biodistribution in rats

Article Title: In vivo tracking of nanoerythrosomes with gallium-68 labeling strategies

Article References: Kunnas, J., Pusa, R., Bakay, E., Lövdahl, P., Ekwe, D., Dillemuth, P., Härkönen, K., Impola, U., Laitinen, S., Rosenholm, J. M., & Li, X.-G. (2026). In vivo tracking of nanoerythrosomes with gallium-68 labeling strategies. EJNMMI Radiopharmacy and Chemistry. https://doi.org/10.1186/s41181-026-00506-3

Image Credits: AI Generated

DOI: 10.1186/s41181-026-00506-3

Keywords: nanoerythrosomes, extracellular vesicles, gallium-68, PET imaging, radiolabeling, biodistribution, rats, drug delivery, radiopharmacy, tris(8-hydroxyquinoline), vivo, tracking