Bio-inspired multifunctional block copolymers for the dissolution of risky atherosclerotic plaques

心血管疾病是全世界发病率和死亡率的一个主要原因。最常见的潜在病理是动脉粥样硬化，它导致动脉血管内膜斑块的形成。动脉粥样硬化是由内皮功能障碍引发的，导致氧化脂蛋白的积累和炎症细胞向新生斑块聚集。这种脂质驱动的慢性炎症导致坏死核心的细胞外脂质沉积。随着坏死核心的脂质增多，内膜中钙化结节的形成意味着斑块破裂的易感性更高。然而，目前侧重于降低全身脂质的预防性治疗策略在临床上对恢复斑块的发展几乎没有影响。在这个提议中，我们打算使用纳米颗粒技术直接从预先存在的动脉粥样硬化斑块中提取脂质和钙沉积，以加速斑块的消退。为了逆转或防止不需要的结晶物质在动脉中聚集，开发了一种基于生物启发和生物相容性的聚（2-恶唑啉）嵌段共聚物的合成策略。选择了一种嵌段共聚物的第一个嵌段由亲水性聚（2-甲基-2-恶唑啉）制成的设计，这应该使共聚物在生物体中具有隐身性能。其他块包含双键或三键侧链。为了使聚合物具有水溶性、胆固醇和钙溶解性，通过巯基键合反应引入亲脂性硫胆固醇侧链，并通过叠氮烷Huisgen环加成引入聚羧酸盐和聚磷酸基团，使其与钙离子发生静电相互作用。我们的初步结果表明，我们的聚合物溶解胆固醇（23.5% wt%）和羟基磷灰石（Ca2+ 4.7 wt%）。作为该项目的一部分，我们的目标是在动脉粥样硬化和人体组织培养的实验模型中测试我们的聚合物设计的治疗潜力，并根据这些结果优化聚合物结构。最初的体内实验测试了聚合物在小鼠模型中的生物利用度、生物分布和消除，随后分析了聚合物治疗对减少动脉粥样硬化斑块大小和组成的功效。动脉粥样硬化病变的基因表达谱增强了组织学和流式细胞术的读数。聚合物治疗对骨密度的潜在不良影响也进行了评估。最后，我们将在体外用我们的聚合物治疗人类动脉粥样硬化斑块组织切片，以测试其对人类的治疗和转化潜力。

Cardiovascular disease represents a major cause of morbidity and mortality worldwide. The most frequent underlying pathology is atherosclerosis, which leads to intimal plaque formation in arterial blood vessels. Atherogenesis is initiated by endothelial dysfunction leading to the accumulation of oxidized lipoproteins and recruitment of inflammatory cells to the nascent plaque. This lipid-driven chronic inflammation results in extracellular lipid deposition in the necrotic core. Alongside the amount of lipid in the necrotic core, the formation of calcific nodules in the intima implies a higher susceptibility for plaque rupture. Yet, current preventive therapeutic strategies focussing on systemic lipid lowering show little impact on reverting plaque development clinically. In this proposal, we intend to directly extract lipid and calcium deposits from preexisting atherosclerotic plaques using nanoparticle technology to accelerate plaque regression.In order to reverse or prevent the agglomeration of unwanted crystalline substances in arteries, a synthesis strategy based on bio-inspired and biocompatible poly(2-oxazoline) block copolymers has been developed. A design is chosen that the first block of the block copolymer is made of hydrophilic poly(2-methyl-2-oxazoline), which should give the copolymers stealth properties in the organism. The other blocks contain double or triple bond side chains. To give them water soluble and cholesterol and calcium dissolving properties, the polymers are post-modified via both thiol-ene click reaction to introduce lipophilic thiocholesterol side chains and azide-alkyne Huisgen cycloaddition to introduce poly carboxylate and poly phosphate moieties, which are supposed to interact with calcium ions electrostatically. Our preliminary results show that our polymers dissolve cholesterol (23.5 wt%) and hydroxyapatite (Ca2+ 4.7 wt%). As part of this project, we aim at testing the therapeutic potential of our polymer designs in experimental models of atherosclerosis and human tissue cultures and optimize the polymer structure according to these results. Initial in vivo experiments testing the bioavailability, biodistribution and elimination of polymers in murine model are followed by analysis of the efficacy of polymer treatment to reduce atherosclerotic plaque size and composition. Histologic and flow cytometric readouts are enhanced by gene expression profiling of atherosclerotic lesions. Potential adverse effects of polymer treatment on bone density are evaluated as well. Finally, we will treat human atherosclerotic plaque tissue slices with our polymers in vitro to test the therapeutic and translational potential for humans.