基于89Zr标记氧化铁纳米颗粒的PET/MRI双模式成像造影剂的开发及其在体示踪树突细胞的研究

基于树突状细胞（DCs）的免疫治疗是一种新兴的、对肿瘤有选择性的微创疗法。了解DCs在体内的迁移途径和迁移特性对提高免疫治疗的效果至关重要。本课题所开发的89Zr整合的氧化铁纳米探针成像性能优良，并且可以高效、安全的标记DCs，利用PET/MRI成像对DCs进行实时无创的长期示踪。其中89Zr的PET成像功能可以准确、定量地监测DCs在体内分布；氧化铁的MRI成像功能可以对标记有探针的细胞进行空间上精确定位。而首创的无需螯合剂在温和的反应条件下对氧化铁纳米颗粒进行放射标记的方法可以最大限度地保持颗粒原本的形貌和表面性质，有利于针对所要标记的细胞调节其表面修饰和靶向分子。此探针的开发有望为DCs示踪提供技术支持,从而更好的了解DCs的在体行为，改善治疗方案，提高免疫疗效。

Dendritic cell (DC) therapy represents an emerging and minimally invasive immunotherapeutic approach for cancer treatment. The improvement of DC therapy would be facilitated by technologies for real-time monitoring of DCs. Herein we develop a novel PET/MRI dual modality imaging probe based on 89Zr-labeled iron oxide nanoparticles to label DCs for long-term and non-invasive cell tracking. 89Zr signal can be monitored in the whole body with high sensitivity and the ability to quantify by using PET. The high resolution anatomical background contrast of MRI allows precise anatomical localization of iron oxide nanoparticle labeled cells. The novel chelator-free radiolabeling method we developed maintains the original properties of nanoparticles, allowing surface engineering of the probe for higher cellular labeling efficiency. The nanoprobe developed in this project may pave the way for DCs tracking to obtain a more in-depth view of in vivo behavior of DCs.