穿膜肽TAT修饰的载药热敏脂质体联合高强度聚焦超声的抗肿瘤研究

Liposome based drug delivery system can improve passive accumulation in tumor interstitium (EPR effect) and reduce free drug toxicity. However, due to inefficient traversal through cellular membranes and insufficient drug release at the tumor site, the in vivo antitumor effects of liposomes were greatly limited. This project combines heat sensitive liposomes modified by cell penetrating peptide-TAT with high intensity focused ultrasound (HIFU), aiming to achieve penetration of cell membranes and complete drug release, ultimately improves antitumor efficacy. After passively accumulated in tumor interstitium, the TAT peptide helps translocate the liposome into the tumor cells. When triggered by HIFU in vivo, the intratumor drug release will be observed by dorsal window chambers. Complete drug release in the tumor site will be achieved when triggered by precise HIFU heating program. Hyperthermia effects of HIFU contribute to the increased drug penetration in tumor site. Therefore, in vivo antitumor effects will be greatly improved. The results of proposed studies contribute to the tumor targeted drug delivery, offering a preclinical foundation for the use of HIFU combines with heat sensitive liposomes for cancer treatment.

临床证明脂质体作为化疗药物的载体可以增强肿瘤间隙的被动蓄积（EPR效应），减轻毒副作用；然而由于细胞膜的天然屏障作用以及肿瘤部位药物释放缓慢，其体内抗肿瘤疗效受到制约。本项目拟通过开发一种同时具有肿瘤细胞膜穿透作用和肿瘤靶向释放功能的新型药物载体和治疗方式，提高化疗药物的抗肿瘤疗效。通过构建穿膜肽TAT修饰的载药热敏脂质体，利用TAT介导的脂质体穿膜转运作用，肿瘤细胞中载药热敏脂质体增多；精确调整HIFU加热方案，在小鼠皮窗模型中实时考察载药热敏脂质体在肿瘤部位的热敏释药效率，实现肿瘤部位快速、充分地释药；同时HIFU本身产生的热效应可以促进药物渗透到肿瘤内部从而进一步提高体内抗肿瘤疗效。本项目的研究成果有助于实现化疗药物的肿瘤靶向递送，为HIFU联合热敏脂质体的临床应用奠定了基础。

肿瘤热疗联合热敏脂质体有助于降低化疗药物剂量，减少全身副作用，提高肿瘤治疗效果。我们设计制备了一种肿瘤靶向肽（iRGD）修饰的热敏载药脂质体，利用主动载药法装载化疗药物盐酸阿霉素。结果显示该脂质体可以特异性结合到肿瘤血管内皮细胞和肿瘤细胞表面的ανβ3整合素受体，提高了肿瘤部位脂质体的蓄积。在荷瘤小鼠实验中，静脉注射脂质体联合高强度聚焦超声，可实现药物的主动靶向，超声温控定点释药的效果，联合HIFU提高了化疗药物的抗肿瘤疗效。该部分实验结果已发表在J Control Release, 243 (2016) 333-341。.在对超声释放热敏脂质体的机制探讨中，我们首次利用超声微流控芯片（Micro-acousticfluidics）通过改变输入射频信号和声致热积累，实现了温度的精确控制，使热敏脂质体温度恒定保持在37℃、42℃和50℃，研究超声的辐射力作用和热效应对药物释放效率及细胞对药物摄取和凋亡效果的评估。该部分研究结果已发表在Theranostics, 2015; 5(11):1203-1213。.我们广泛拓展应用开展肿瘤的多种综合治疗，构建了载ICG的iRGD靶向修饰脂质体，提高ICG的稳定性和肿瘤靶向富集能力，在近红外激光照射下，肿瘤区域温度迅速升高，产生单线态氧，利用此光热效应靶向杀伤肿瘤细胞，相关研究结果已发表在J Control Release, 224, 217-228, 2016。同时我们还开展了IR-780联合超声声动力疗法对小鼠乳腺癌的治疗，IR-780联合超声在肿瘤细胞内引发活性氧，从而杀伤肿瘤细胞，抑制小鼠乳腺癌的生长，相关研究结果已发表在Scientific Reports, 6 (2016)。