基于肿瘤微环境响应的超声/MRI/荧光三模式成像用于肝癌病理可视化及其机制

Early diagnosis and treatment of liver cancer remain the hot but challenging medical issue. Unfortunately, although the currently conventional imaging means can acquire the anatomical structure information to some extent, they all fail to realize the visualization of pathological components in tumors. Detecting tumor microenvironment (TME) biomarkers using some noninvasiveness technologies is expected to become another important means capable of visualizing pathology information in tumor. Basing on the accumulative experience in TME detection using MRI approach, we will construct a TME-responsive ultrasound/MRI/fluorescence trimodal imaging (i.e., Si-QDs@MnO2-NSs). Relying on the principle of the Fenton-like reaction between MnO2 nanosheets and H2O2/H+ in tumor, Mn2+-enhanced MRI, O2-enhanced ultrasound imaging and recovered fluorescence imaging of Si-QDs will be acquired. Furthermore, laser confocal scanning microscopy, flow cytometry, UV-Vis spectrometer, etc., will be used to explore the principle of TME-triggered intensified trimodal imaging and evaluate the feasibility of acidicity and H2O2 detection in tumor, providing a new method and theoretical basis for improving the diagnostic accuracy of clinical liver cancer and safety of pathological information.

肝癌的早期有效诊断及治疗的方法已成为目前医学研究的热点与难点问题。然而目前存在的传统影像学方法虽然在某种程度上可实现解剖结构信息获取，但这些诊断都无法实现肿瘤内部病理成分的可视化。肿瘤微环境标志物的影像检测有望成为除穿刺外实现肿瘤病理可视化的另一个重要手段。基于本课题组在肿瘤微环境MRI成像方面积累的经验，本项目拟通过构建一种肿瘤微环境响应的超声/MRI/荧光三模式探针——Si-QDs@MnO2-NSs，利用该探针中MnO2纳米片在肿瘤酸性和H2O2环境下发生类芬顿反应，实现Mn2+增强MRI成像、O2增强超声成像以及Si-QDs恢复的荧光成像。进一步，通过共聚焦、流式细胞仪、紫外-可见吸收谱、电子自旋共振等手段考察肿瘤微环境刺激响应增强三模式成像机制以及在肿瘤酸性和H2O2探测方面的可行性，为提高临床肝癌诊断精度以及病理信息确认安全性提供新的方法和理论依据。

肝细胞癌（HCC）是全球第四常见的癌症死亡原因。晚期肝癌的治疗策略仍然有限。Survivin是一种凋亡抑制蛋白。本研究旨在探讨携带survivin小干扰RN（siRNA）的纳米颗粒用于肝癌的成像和基因治疗的价值。采用PEI修饰氧化铁纳米颗粒，然后与survivin siRNA、Cy7和/或抗AFP抗体结合，获得靶向纳米颗（siRNA@FeNP）或对照siRNA@FeNP（NC-siRNA@FeNP)。在体外和体内动物实验检测细胞对载siRNA纳米颗粒摄取、细胞凋亡、迁移、体内肿瘤大小的影响，并检测survivin基因和蛋白表达的改变。通过普鲁士蓝染色可以看到靶向组细胞摄取纳米颗粒显著多与非靶向组。MRI成像也同样显示靶向组T2WI信号显著低于非靶向组。靶向组细胞凋亡数量显著高于非靶向组，而细胞迁移能力显著低于非靶向组。靶向组肿瘤细胞Survivin基因表达显著下调。动物研究也显示靶向组肿瘤T2WI 信号及荧光信号显著低于非靶向组，干预后靶向组肿瘤大小低于非靶向组。靶向组肿瘤组织Survivin基因和蛋白表达明显低于非靶向组。本研究构建的载Survivin小干扰RNA纳米颗粒可以靶向肝癌细胞及肿瘤，并能诱导肿瘤细胞凋亡，抑制肿瘤生长。在肝癌诊疗一体化方面具有潜在价值。