Gene delivery using polyion complex micelle for the treatment of aortic aneurysm

(1)新型聚离子复合胶束的研制为了提高基因转移效率，我们研制了两种新型的聚离子复合胶束。一种是添加环状RGD多肽的PCI胶束。环状RGD多肽可增强血管内皮细胞和血管平滑肌细胞对PCI胶束的递送特异性。另一种胶束是聚乙二醇二乙醇胺，它可以促进胶束在细胞内从内体到细胞质的运动(内体逃逸)。(2)小鼠主动脉瘤模型鉴于大鼠主动脉瘤基因转移需要大量的聚乙二醇单抗胶束，我们的目的是建立小鼠主动脉瘤模型。先前的研究表明，持续给予血管紧张素II可能会导致主动脉瘤的形成。我们尝试了相同的血管紧张素II给药方案，但大多数情况下都发生了由于夹层导致的主动脉破裂。通过改变给药剂量和给药时间，在小鼠模型中未观察到真性动脉瘤的形成。(3)大鼠颈动脉新生内膜模型的基因转移效率由于不能建立小鼠主动脉瘤模型，我们决定通过向大鼠颈动脉新生内膜传递基因转移胶束来评价体内基因转移效率。首先，用球囊导管损伤大鼠颈动脉，造成新生内膜损伤。伤后3周，将含有标记基因DNA的PIC胶束注入动脉腔内，孵育20min。孵育后恢复血流，3d后进行基因表达检测。目前，我们正在该模型上评价添加RGD的环状PCI胶束的基因转移效率。

(1) Development of novel polyion complex micelles (PCI micelles)To improve gene transfer efficiency, we developed two types of novel PCI micelles. One is PCI micelle added with circular RGD peptide. Circular RGD peptide could enhance delivery specificity of PCI micelle for endothelial cell and vascular smooth muscle cell. Another micelle is PEG-DET, which could promote intracellular-movement of micelle from endosome to cytoplasm (endosomal escape).(2) Mouse model of aortic aneurysmSince large amount of PCI micelle is necessary for gene delivery to rat aortic aneurysm, we aimed to establish mouse model of aortic aneurysm. Previous studies showed that continuous administration of angiotensin II potentially induced formation of aortic aneurysm. We tried the same protocol of angiotensin II administration to mouse, but aortic rupture due to dissection occurred in most of cases. Although we changed administration dose and delivery period, no formation of true aneurism was observed in mouse model.(3) Evaluation of gene transfer efficiency using neointimal model of rat carotid arteryBecause mouse model of aortic aneurysm could not be established, we decided to evaluate in vivo gene transfer efficiency of PCI micelle by delivering to neointima of rat carotid artery. First, rat carotid artery was injured with balloon catheter to induce neointimal lesion. At 3 weeks after the injury, PIC micelle containing marker gene DNA was administrated into the arterial lumen and incubated for 20 minutes. After the incubation, blood flow was resumed, and 3days later, gene expression was evaluated. Now, we are evaluating gene transfer efficiency of circular RGD-added PCI micelle on this model.