基于唐氏模型小鼠Tc1探讨可防治动脉粥样硬化的miRNA子集及其靶向输送策略

动脉粥样硬化（AS）严重威胁人类生命健康，探讨其发病机制及干预策略具有重要意义。临床研究表明，唐氏综合征（又称21-三体综合征）患者AS发病率低，提示21号染色体上存在重要的AS保护因子。我们前期引进唐氏模型小鼠Tc1（NSFC 81170149），发现该模型小鼠高脂饮食后几乎无斑块发生；对其中额外的232个基因进行深入的功能聚类和生物信息学分析发现，miR-99/125b/let7c可调控多条AS相关通路，提示这些miRNAs可能是重要的AS保护因子。本项目拟在细胞和整体动物水平上，明确上述miRNAs在抑制AS发生中的作用和具体机制；此外，结合外泌体药物靶向输送优势，设计靶向受损血管的外泌体并加载上述miRNAs，系统评价改构外泌体对小鼠AS的靶向性及对AS发生发展的影响。本项目有望发现新的AS保护因子，创建一种新的AS靶向输送基因药物方法，为动脉粥样硬化的防治提供全新的靶向干预策略。

Atherosclerosis (AS) is a life-threaten disease, due to the possible eruption of the vulnerable plaques. Elucidation of the underlying mechanism and development of the therapeutic strategies is of great theoretical and clinical importance. Accumulating clinical evidence indicates that patients with Down syndrome, who harbor one additional copy of Chromosome 21, have much lower incidence of atherosclerosis, suggesting that certain genes in the Chromosome 21 should be anti-atherogenic. Identification and characterization of these protective factors are pre-requisite for therapeutic delivery to the diseased blood vessels, both of which would shed light on the treatment of atherosclerosis. With the support of the NSFC (81170149), we have imported the Tc1 mice, which harbor the most portion of the human chromosome 21 and mimic the phenotype of Down syndrome. We have revealed that Tc1 mice display lower impairment of the endothelium and infiltration of immune cells under high fat diet, and plaques were rarely found. There are estimated 232 genes in the transferred Chromosome 21, with miRNAs included. Functional cluster and other bioinformatics analysis imply that miR-99/125/let7c are possibly the potent anti-atherogenic factors. The proposed project would first confirm the protective role of the miRNAs candidates miR-99/125/let7c in vitro and in vivo, by combinatorial use of control and Tc1 mice. The cellular and molecular mechanisms for their protective roles would be also clarified. With the advance of exosome in targeted drug delivery, we next would focus on deliver the above protective miRNAs to the diseased blood vessels by modification of the natural exosome. Briefly, Lamp2b protein, the key components of exosome membrane, is fused with RGD by molecular cloning, which would specifically recognize the inflammatory endothelium. After purification of the exosome, candidate miRNAs drugs would be loaded into the exosome by electroporation. The targeted specificity and therapeutic efficacy would be systemically evaluated by both histology and echocardiography. The current proposal would be promisingly find novel anti-atherogenic genes and establish new treatments for this disease.