Miederer Matthias, Pektor Stefanie, Miederer Isabelle, Bausbacher Nicole, Keil Isabell Sofia, Hefesha Hossam, Haas Heinrich, Sahin Ugur, Diken Mustafa
Department of Nuclear Medicine, University Medical Center of Johannes Gutenberg University, Mainz, Germany.
TRON - Translational Oncology at the University Medical Center, Johannes Gutenberg University Mainz gGmbH, Mainz, Germany.
EJNMMI Res. 2021 Feb 10;11(1):14. doi: 10.1186/s13550-021-00753-2.
RNA-based vaccination strategies tailoring immune response to specific reactions have become an important pillar for a broad range of applications. Recently, the use of lipid-based nanoparticles opened the possibility to deliver RNA to specific sites within the body, overcoming the limitation of rapid degradation in the bloodstream. Here, we have investigated whether small animal PET/MRI can be employed to image the biodistribution of RNA-encoded protein. For this purpose, a reporter RNA coding for the sodium-iodide-symporter (NIS) was in vitro transcribed in cell lines and evaluated for expression. RNA-lipoplex nanoparticles were then assembled by complexing RNA with liposomes at different charge ratios, and functional NIS protein translation was imaged and quantified in vivo and ex vivo by Iodine-124 PET upon intravenous administration in mice.
NIS expression was detected on the membrane of two cell lines as early as 6 h after transfection and gradually decreased over 48 h. In vivo and ex vivo PET/MRI of anionic spleen-targeting or cationic lung-targeting NIS-RNA lipoplexes revealed a visually detectable rapid increase of Iodine-124 uptake in the spleen or lung compared to control-RNA-lipoplexes, respectively, with minimal background in other organs except from thyroid, stomach and salivary gland.
The strong organ selectivity and high target-to-background acquisition of NIS-RNA lipoplexes indicate the feasibility of small animal PET/MRI to quantify organ-specific delivery of RNA.
基于RNA的疫苗接种策略可针对特定反应调整免疫反应，已成为广泛应用的重要支柱。最近，基于脂质的纳米颗粒的使用为将RNA递送至体内特定部位开辟了可能性，克服了在血液中快速降解的限制。在此，我们研究了小动物PET/MRI是否可用于成像RNA编码蛋白的生物分布。为此，在细胞系中体外转录编码碘化钠同向转运体（NIS）的报告RNA，并评估其表达。然后通过将RNA与脂质体以不同电荷比复合来组装RNA-脂质复合物纳米颗粒，并在小鼠静脉注射后通过碘-124 PET在体内和体外对功能性NIS蛋白翻译进行成像和定量。
早在转染后6小时就在两种细胞系的膜上检测到NIS表达，并在48小时内逐渐下降。与对照RNA脂质复合物相比，阴离子型脾脏靶向或阳离子型肺靶向NIS-RNA脂质复合物的体内和体外PET/MRI显示，脾脏或肺中碘-124摄取在视觉上可检测到快速增加，除甲状腺、胃和唾液腺外，其他器官的背景极小。
NIS-RNA脂质复合物具有很强的器官选择性和高靶本底比，表明小动物PET/MRI对RNA器官特异性递送进行定量的可行性。
