SMAD3基因缓释微粒的制备及其治疗腹主动脉瘤的实验研究

Abdominal aortic aneurysm (AAA) is a common life-threatening disease with high mortality rate if ruptured. Surgical therapy remains the only treatment in clinic. No effective drug treatment has been discovered yet. It’s urgent to explore an effective method for treating AAA. Our previous analysis of AAA specimens from patients has found SMAD3 expression was significantly reduced in AAA. SMAD3 is known as the core of classic TGFβ signaling pathway. This study will select recombinant plasmid as a vector carrying the signal transduction protein SMAD3 gene. Alginate hydrogel, a biodegradable material, will be used to construct nanoscale drug particles which will attach to the rat abdominal aortic aneurysm animal models. Drugs of nanoparticles have the quality of sustained release and targeting, which will make the drug steadily and sustainably effect on the aneurysm with high concentration at specific sites and release the SMAD3 plasmids for efficient transfection, expression SMAD3 signaling proteins, which could regulate TGFβ/Smads signaling pathway, promoting regulatory T cells (Tregs) amplification or enhancement. That will reduce inflammation and matrix metalloproteinases (MMPs) secretion to protect the load structure of aneurysm wall in order to manage and treat AAA. This study may develop a new avenue to further define the pathogenesis of AAA, improve clinical drug therapy and the existing surgical equipment.

腹主动脉瘤（AAA）是一种常见的危及生命的疾病，一旦破裂死亡率极高。手术疗法仍是唯一的治疗手段，目前临床上尚无治疗AAA的药物，探索治疗AAA的有效方法迫在眉睫。我们前期对患者AAA血管标本的分析发现，AAA中SMAD3表达明显下调。已知SMAD3是TGFβ经典信号通路的核心。故本研究将拟选用重组质粒作为载体承载信号传导蛋白SMAD3基因，使用可降解材料海藻酸盐水凝胶构建缓释基因药物，将其附着于大鼠腹主动脉瘤动物模型瘤体，使药物在局部靶向性、持续、高浓度地作用于瘤体，缓释所承载的SMAD3质粒，实现高效的转染，表达SMAD3信号蛋白，调控TGFβ/Smads信号通路，促进调节性T细胞（Tregs）扩增或增强功能，减少炎症反应，减少基质金属蛋白酶（MMPs）分泌，保护瘤壁负载结构，以达到控制和治疗AAA的目的。为进一步明确AAA发病机制、药物治疗AAA和改进现有手术器材的临床研究开辟新途径。

腹主动脉瘤（AAA）是发生于肾下段腹主动脉的主动脉扩张性且危及生命的疾病。目前临床上，外科手术是唯一治疗方法，目前尚无治疗AAA的药物，如能通过药物治疗抑制AAA的进展，甚至使瘤体缩小，减少AAA破裂率，会对AAA的治疗产生革命性变化。本研究主要探索了SMAD3基因缓释微粒制备及其对腹主动脉瘤的治疗效果。我们首先使用大鼠和小鼠建立了AAA动物模型，实验表明均能成功建模，综合考虑，我们采用小鼠AAA模型进行药物实验，然后进行动物分组，包括对照组、建模组、假手术组、治疗组，在治疗组中，我们采用海藻酸盐凝胶+SMAD3过表达质粒行腹主动脉旁浸润。在4周后，收集主动脉瘤标本，记录大体数据，并行组织学、免疫学、分子生物学等检测评估。结果表明，使用新型缓释水凝胶基因药物的AAA小鼠，与假手术组建模组对比，成瘤率明显下降，主动脉直径较小（P1＜0.001；P2＜0.001），治疗处理可显著增加小鼠主动脉中SMAD3、p-SMAD3和TGF-β的表达，降低小鼠主动脉中MMP-2的表达，并显著降低主动脉平滑肌细胞的凋亡，T淋巴细胞及巨噬细胞浸润。实验结果表明，SMAD3基因质粒能通过海藻酸盐凝胶稳定表达SMAD3基因和蛋白，并能通过抑制基质金属蛋白酶水解、炎症、T淋巴细胞浸润和平滑肌细胞的凋亡来抑制Ang-II诱导的小鼠AAA的发展。它可能是一种AAA的新型基因治疗方法。项目资助发表SCI论文4篇，中文论文3篇。培养博士研究生2名，硕士研究生3名，其中2名取得博士学位，1名取得硕士学位。项目投入经费17.0000万元，支出16.3653万元，各项支出与预算相符，剩余经费0.6347万元，计划用于本项目后续支出。