靶向肿瘤干细胞及其微环境分子探针的构建及在体的可视化研究

Cancer stem cells (CSCs) play a critical role in the tumor development, recurrence, metastasis and drug resistance, and have attracted wide attention. However, because of its scarcity, high heterogeneity and plasticity, it is difficult to isolate and detection of biological behavior in vitro and in vivo. Finding and identifying the specific surface markers and understanding the related regulatory mechanisms of CSCs behaviors is crucial to developing the new strategies for cancer targeted and personalized therapies in the future．This project is aiming at to use multimodal imaging techniques to investigate the complexity behavior of CSCs and the relationships of hypoxic microenvironment. Firstly, we design variety of multi-site recognition targeting peptides to assemble into a topologically structured on the surface of the nanoparticles and to separation of high purity CSCs and identification its stemness in vitro. Secondly, rare-earth upconversion luminescent nanoparticles as functional carriers, by optimizing element doping and surface functionalization to construct cancer stem cells and hypoxic specificity multimodal imaging probes. Finally, the multifunctional probe not only dynamically visualizing intratumoral of CSCs number, hypoxia level, and spatial distribution characteristics with high spatial resolution and sensitivity, but aslo provide a novel tool to understand the relationship between the hypoxia and CSCs in vivo. It will facilitate the development of new therapeutic targets and novel strategies for the treatment and prognosis of cancer.

肿瘤干细胞（Cancer stem cells，CSCs）在肿瘤的发展、复发、转移和耐药中扮演者极其重要的角色，引起了人们的广泛关注。然而由于其数量少、且具有高度异质性和可塑性等特点使它的体内生物学行为的检测成为难点。本项目拟利用多模态分子影像探针研究肿瘤干细胞体内行为的复杂性以及乏氧微环境对其行为的调控作用。首先，设计多种多位点识别的靶向肽段，发展表面具有组装拓扑结构多肽的磁性纳米颗粒结合磁分离，实现CSCs体外的高纯度分离和鉴定；其次，以稀土上转换发光纳米颗粒为功能载体，通过优化元素掺杂及表面功能化修饰构建肿瘤干细胞和乏氧特异性的多模态分子影像探针并进行体外评价；最后，通过多功能纳米探针对活体肿瘤内的CSCs含量、乏氧程度和二者在肿瘤内的空间分布特点以及乏氧对CSCs的动态调控进行无创的可视化研究，为肿瘤的检测、治疗及预后评估等临床研究提供新的思路与依据。

肿瘤干细胞（CSCs）作为肿瘤发生、发展、复发、耐药的根源，在近年受到广泛关注。CSCs所占比例非常小，且缺乏特异性的标志物，使它的分离、富集和体内检测成为当前肿瘤干细胞研究的瓶颈和难点。如何有效地对CSCs进行示踪，从而实时监控CSCs在体内外的生物学行为有助于临床诊断和选择正确的治疗方法。本项目围绕肝癌精准诊疗的临床需求，通过肝癌肿瘤干细胞标志物CD133、CD13和EpCAM等标志物设计靶向亲和多肽，利用多靶点组合识别策略结合磁分离实现了肝癌肿瘤干细胞的高效富集、分离及相关的细胞生物学特性研究。并基于多靶点靶向策略构建上转换荧光和MRI多模态分子影像探针实现了体内肿瘤干细胞空间分布的可视化研究。同时设计了一种GSH响应的CD133和EpCAM双靶向脂质体给药系统，能够同时递送阿霉素(Dox)和沙利霉素(Sal)协同消除CSCs和非CSC细胞实现肝癌的有效治疗。以上研究成果为肝癌CSCs的动态可视化监测、靶向治疗以及预后评估提供了参考。