适配体BzdU修饰的双靶向温度响应脂质体用于胰腺神经内分泌肿瘤诊疗的研究

The insidious onset of pancreatic neuroendocrine noeplasms (pNENs) make it difficult to be diagnosed early, and there are different degrees of drug resistance and side effects during chemotherapy of pNENs with temozolomide (TMZ). This project aims to synthetize an intelligent nano-probe targeted to pNENs to improve the diagnostic accuracy and therapeutic effect. The thermosensitive liposomes (TSL) was used as a drug carrier. As the high expression of vascular endothelial growth factor 2 (VEGFR2) on the tumor cells and vascular endothelial cells of pNENs, the new ligands, aptamer BzdU which can identify VEGFR2, will be covalently linked on the surface of TSL make it dual targeted to pNENs tumor cells and tumor vessels. Then TMZ was dissolved in the TSL lipid layer, and the near infrared (NIR) photothermal agent IR-820 and MRI contrast agent Gd-DTPA were sealed in the hydrophilic core of TSL. The photothermal conversion of IR-820 will heat the TSL, make it crack and the drug release. MRI/NIR dual mode imaging of pNENs by Gd-DTPA and IR-820 is used for the accurate diagnosis of pNENs. Photothermal conversion of IR-820 and the release of TMZ from TSL can achieve the combined treatment of photothermal and chemotherapy, reduce the toxic and side effects of TMZ and enhance the curative effect. This project is expected to provide a new and effective way in accurate diagnosis and target combination therapy of pNENs.

胰腺神经内分泌肿瘤（pNENs）早期诊断困难，TMZ化疗无靶向性且毒副作用大。本项目拟制备一种靶向智能纳米探针以提高pNENs诊断的准确性和治疗疗效。以温敏脂质体（TSL）为载体，利用血管内皮生长因子2（VEGFR2）于pNENs肿瘤细胞及血管内皮细胞同时高表达的特点，将识别VEGFR2的适配体BzdU共价链接于TSL表面，实现探针对pNENs肿瘤细胞及血管内皮的双主动靶向。将TMZ溶于TSL类脂质层，将近红外（NIR）光热制剂IR-820及MRI对比剂Gd-DTPA封包于TSL亲水核心。利用IR-820行光热转换促使TSL升温裂解并释放药物，Gd-DTPA、IR-820可实现MRI/NIR双模态成像，有助于pNENs准确诊断。光热转换及TMZ的释放可实现肿瘤的光热/化疗联合治疗，降低TMZ的毒副作用并增强疗效。本项目有望为pNENs精准诊断和靶向联合治疗提供一种全新有效的途径。

本项目拟利用血管内皮生长因子2（VEGFR2）于胰腺神经内分泌肿瘤（pNENs）肿瘤细胞及血管内皮细胞同时高表达的特点，制备集pNENs肿瘤细胞及血管双重主动靶向、MRI/NIRF双模态成像、光热/化疗联合治疗于一体的智能纳米探针。项目研究内容包括：通过叠氮-炔基“Click-reaction”共价链接脱乙酰壳多糖（chitosan, Cs）与 BzdU 合成配体复合物 BzdU-Cs，使 BzdU 在体循环内具有良好的稳定性及恒定的三维结构，并易于通过 Cs将BzdU共价链接于温敏脂质体表面，提高纳米探针对 pNENs 肿瘤细胞及微血管内皮的 VEGFR2 双重靶向特性。将疏水性化疗药TMZ溶于TSL类脂质层内，将亲水性近红外光热制剂IR-820及磁共振对比剂Gd-DTPA封包于其亲水核心内，并在其表面修饰识别VEGFR2的适配体BzdU。构建具有pNENs双重靶向、MRI/NIRF双模态成像和光热/化疗联合治疗一体化的智能纳米探针。目前已对该双靶向只能纳米探针的MRI显像功能进行表征及验证，提示该探针MRI显像灵敏。项目研究下一步将通过光热转换及TMZ的释放测试该只能纳米探针的肿瘤光热/化疗联合治疗疗效，优化探针性能，降低TMZ的毒副作用并增强疗效。本项目有望为pNENs精准诊断和靶向联合治疗提供一种全新有效的途径。