基于脂质筏的新型纳米载药系统的设计、构建和性能研究

Recently, cell plasma membrane derived vesicles have received increasing attention, especially shredded exosomes and microparticles for siRNA and drug delivery. As naturally derived materials, theses vesicles composed of phospholipids, cholesterol, and membrane proteins are completely biocompatible which makes them the idea platform for therapeutic and diagnostic purposes. Despite the exciting discovery of the exosomes/microparticles as a promising carrier for both therapeutic and diagnostic agents, the further development and potential translation of this technology are currently limited by the lack of suitable and scalable technologies for the therapeutic loading and vesicle purification.. Here we aim to develop a platform technology that can solve the challenges in the fabrication and engineering of exosomes/microparticles. Specifically, we will fabricate a biocompatible vesicles (Raftosome) by self-assembly of purified cell membrane extract, mainly lipid rafts separated from other cellular components using the density gradient. The loading of therapeutics in Raftosomes is simple, scalable, and conviently combined with the preparation of Raftosome. Right before the disruption of cell membrane and extraction of lipid raft, we just need either genetically express the peptides tethered with transmembrane domain on the plasma membrane or chemically engraft the lipidated peptides on the extracellular plasma membrane. Once presented in the lipid raft, the activity of peptides is preserved during the isolation steps and bioactive on the later self-assembled Raftosomes.. As a proof-of-concept, we will genetically express Exendin-4 (EXE-4), a therapeutic peptide targeting GLP-1 receptors for the treatment of type II diabetes, on the plasma membrane of mesenchymal stem cells based on the tether-ligand technology we developed previously. EXE-4 Raftosomes will be made through mechanical cell disruption, lipid raft purification, and self-assembly. Once prepared, we will examine their physical properties (hydrodynamic diameter and zeta potential),molecular composition, and recognition by immune system. We will also compare the yield with that of exosomes purified through the traditional ultracentrifugation. The release profile of EXE-4 from EXE-4 Raftosome will also be examined.. The specificity and function of EXE-4 on Raftosome will be studied through examing their interaction with pancreatic beta cell line MIN6. In addition to the uptake and labeling experiments, we will focus on investigating whether the EXE-4 Raftosomes could improve the survival rate and the glucose response of MIN6 cells speroid in vitro, which will have a huge impact in the transplantation of primary beta cells for the treatment of type I diabetes

纳米载药控释系统是结合现代纳米技术而产生的一种药物载体, 它具有靶向性、缓释性、表面可修饰性、可生物相容和降解等显著特点。它们增强了药物在体内的稳定性，提高药物的生物利用度，并减缓了副作用。近日，国际科技界突破性地发现细胞膜的衍生物-外切体也能作为一种药物载体将药物譬如siRNA靶向地运送到细胞或组织里。相对于其他纳米药物载体，外切体的优势在于：一没有免疫原性，二可以同时利用所载药物和自身表面一些功能性的蛋白质来调控目标细胞内的多种信号通道。但是对于这种细胞自然分泌的材料，一个现实的挑战是如何大量地合成它们并高效地将药物包裹在其中。针对这一难题，本课题探讨是否可以人为大量地合成一种类似于外切体的药物载体。在早期研究基础上，本课题将利用生物或者化学的方法将活性药物如多肽激素Exedin-4修饰在间充质干细胞的脂质筏上，而后通过梯度分离、脂质筏自组装等技术来设计并合成类似于外切体的新型药物载体

多功能纳米载药控释系统是结合现代纳米技术而产生的一种药物载体, 它具有靶向性、缓释性、表面可修饰性、可生物相容和降解等显著特点，不仅增强了药物在体内的稳定性，提高药物的生物利用度，还可以减少副作用。本课题设计并构建了一系列新型的药物载体将活性药物譬如siRNA运送到特定的细胞或组织里并实现影像系统可视化监控。在研究工作中，成功实现了对基因载体结构功能的可控制备，可以在体外高效转染肿瘤细胞，同时转染效果可以通过磁共振T1，T2双模式成像无创观察，实现了基因转染的高灵敏无创MRI影像可视化。构建了脂质筏的细胞膜自主装成纳米囊泡并实现了将药物装载到细胞膜来源的纳米囊泡中，提高药物治疗效果并降低毒副作用。本课题负责人多次参加本领域专业学术会议并做邀请报告。通过本项目的开展，已发表 SCI 收录论文3 篇（部分工作投稿中）。上述研究为我们在后续课题中进一步开展更加深入系统的肿瘤诊疗一体化研究奠定了坚实的基础。