双靶双模态分子探针增强脑胶质瘤特异性成像的研究

The objective of this research is to construct a glioma-specific dual-modality and dual-ligand conjugated molecular imaging probe via sequential loading near-infrared dye Cy5.5, polyethylene glycol (PEG), dual targeting ligands chlorotoxin (CTX) and cRGDyK to the surface of superparamagnetic iron oxide (SPIO) nanoparticles. Herein, SPIO is used for the preoperative MRI diagnosis of glioma while Cy5.5 for the intraopertive delineation of glioma margins. CTX and cRGDyk are used as dual-ligand to enhance the targeting specificity toward brain glioma, resulting in an enhanced the brain glioma-specific imaging. The contents of this research are as follows, (1) to synthesize the dual-modality, dual-ligand conjugated molecular imaging probe with high dispersibility and stability; (2) to optimize the number and ratio of two ligands in order to obtain the highest targeting specificity toward glioma; (3) to assess the accuracy of preoperative MRI of glioma and the precision of intraoperative NIRF delineation of tumor margins; (4) to evaluate the in vitro and in vivo biocompatibility of designed molecular probe. The expected results of this research are (1) to obtain a dual-modality, dual-ligand conjugated molecular probe with high specificity to glioma; (2) to establish an approach for optimizing the number and ratio of two targeting ligands; (3) to provide a novel and cost-effective strategy for preoperative MRI diagnosis of glioma and intraoperatuve NIRF delineation of glioma tumor. The above achievements will be great beneficial for improving the accuracy of preoperative MRI diagnosis and the precision of intraoperative NIRF image-guided resection of glioma tumor.

构建一种对脑胶质瘤特异性成像的双靶双模态（MRI/NIRF）分子影像探针，即在超顺磁氧化铁表面依次偶合近红外荧光探针Cy5.5、聚乙二醇和双靶CTX、cRGDyK。其中超顺磁氧化铁用于胶质瘤的术前MRI诊断，Cy5.5用于术中NIRF成像确定胶质瘤边界，双靶偶合用于增强分子探针对脑胶质瘤的特异性。本项目研究内容：1)探索高分散高稳定的双靶双模态分子探针的制备路线和工艺条件；2)体外实验确定对胶质瘤细胞特异性最佳的双靶数及配比；3)体内实验评价双靶探针对脑胶质瘤术前成像的准确性及术中NIRF成像确定的边界与病理学边界的相符程度。4)评价分子探针的体内外安全性。预期研究成果：1)获得对脑胶质瘤高度特异性的双靶双模态分子探针。2)建立双靶配比优化的方法。3)提供一种脑胶质瘤术前诊断和术中界定边界的新策略。本研究成果有望极大提高脑胶质瘤术前MRI诊断和术中NIRF成像界定胶质瘤边界的准确性。

氧化铁纳米粒可用于增强脑胶质瘤磁共振（MR）T2 成像的对比。但该造影剂缺乏对脑胶质瘤的特异性，致使在脑胶质瘤的累积量不足，导致 MR 强化不明显。为增强氧化铁对脑胶质瘤的特异性，本项目采用超顺磁氧化铁（Fe3O4）纳米粒，偶合近红外分子探针Cy5.5，再连接RGD/FA或CTX/FA双靶，构建双靶、双模态（MRI/NIRF）分子影像探针。主要研究成果有：（1）双靶密度可影响探针对胶质瘤的靶向特异性；（2）双靶相对长度可影响探针对胶质瘤的靶向特异性；（3）双靶Fe3O4纳米粒能显著增强脑胶质瘤的 MR 成像对比效果。（4）双靶Fe3O4纳米粒有良好的生物相容性；（5）制备出一种新型的碳酸锰 T1 造影剂，该造影剂能明显增强胶质瘤的 MR 对比效果。重要结论：双靶修饰的Fe3O4纳米粒可增加对胶质瘤的靶向特异性，并最终增强胶质瘤的对比效果；靶向特异性可通过调整双靶密度和双靶不同相对长度来优化。本项目的双靶、双模态Fe3O4纳米探针提高了脑胶质瘤的诊断准确性，为向临床转化奠定了坚实基础。共发表SCI研究论文20篇。