Industrial Ph.D Program of Biomedical Science and Engineering, National Yang-Ming University, Taipei, Taiwan.
Molecular and Genetic Imaging Core/Taiwan Mouse Clinic, National Comprehensive Mouse Phenotyping and Drug Testing Center, Taipei, Taiwan.
Mol Imaging Biol. 2021 Jun;23(3):361-371. doi: 10.1007/s11307-020-01562-0. Epub 2020 Nov 20.
Mesenchymal stem cell-derived EVs (MSC-EVs) are demonstrated to have similar therapeutic effect as their cells of origin and represent an attractive cell-free stem cell therapy. With the potential to be the future medical regimen, the information of fate and behavior of MSC-EVs in the living subject should be urgently gathered. This study aimed to track MSC-EVs by In-labeling and μSPECT/CT imaging.
Wharton's jelly-MSC-EVs (WJ-MSC-EVs) were isolated using Exo-Prep kit followed by characterization of expressing markers and size. After labeled by In-oxine, In-EVs were injected into C57BL/6 mice followed by μSPECT/CT imaging. Organs were then taken out for ex vivo biodistribution analysis.
The radiochemical purity of In-EVs was > 90 % and remained stable up to 24 h. The image results showed that with injection of In-EVs, the signal mainly accumulated in the liver, spleen, and kidney, compared to that in lung and kidney after In-oxine injection. The ex vivo biodistribution showed the similar pattern to that of imaging. Chelation of free In with EDTA was found necessary to reduce the nonspecific accumulation of signal.
This study demonstrated the feasibility of radiolabeling WJ-MSC-EVs with In-oxine for in vivo imaging and quantitative analysis in a mouse model. This simple and quick labeling method preserves the characteristics of WJ-MSC-EVs. The results in this study provide a thorough and objective basis for future clinical study.
间充质干细胞衍生的细胞外囊泡（MSC-EVs）被证明具有与其起源细胞相似的治疗效果，是一种有吸引力的无细胞干细胞治疗方法。由于有成为未来医疗方案的潜力，因此应迫切收集活体内 MSC-EVs 的命运和行为信息。本研究旨在通过 In 标记和 μSPECT/CT 成像来追踪 MSC-EVs。
使用 Exo-Prep 试剂盒分离 Wharton 胶 MSC-EVs（WJ-MSC-EVs），然后对表达标志物和大小进行表征。用 In-oxine 标记后，将 In-EVs 注射到 C57BL/6 小鼠中，然后进行 μSPECT/CT 成像。然后取出器官进行离体生物分布分析。
In-EVs 的放射化学纯度>90%，在 24 小时内保持稳定。图像结果显示，与 In-oxine 注射相比，注射 In-EVs 后，信号主要在肝脏、脾脏和肾脏中积累，而不是在肺和肾脏中积累。离体生物分布显示出与成像相似的模式。发现用 EDTA 螯合游离 In 对于减少信号的非特异性积累是必要的。
本研究证明了用 In-oxine 对 WJ-MSC-EVs 进行放射性标记用于在小鼠模型中进行体内成像和定量分析的可行性。这种简单快捷的标记方法保留了 WJ-MSC-EVs 的特性。本研究的结果为未来的临床研究提供了全面客观的基础。
