Multimodal nanoagents for the detection and treatment of atherosclerosis

描述(申请人提供)：最近开发了多种新的纳米材料，主要分布在巨噬细胞和巨噬细胞亚型中。这些材料已被用于疾病的诊断，其中巨噬细胞在发病机制中发挥关键作用。例如，我们已经开发出可通过磁共振和光学成像检测的基于葡聚糖的超顺磁性氧化铁(磁性荧光)纳米颗粒，并已将其用于淋巴结、动脉粥样硬化、类风湿性关节炎、糖尿病和其他疾病的巨噬细胞靶向。其中一些材料的临床试验目前正在进行中。巨噬细胞，特别是激活的巨噬细胞，是动脉粥样硬化血管的关键组成部分，可占罪犯病变中存在的细胞的10%-20%。巨噬细胞分泌蛋白水解酶，导致纤维帽的降解，促进动脉粥样硬化血栓形成，和/或在进行性炎症级联中发挥其他关键作用。我们最初的假设是，选择性地“沉默”激活的巨噬细胞可能会产生长期的治疗效果。因此，我们将光激活的治疗部分连接到纳米颗粒上。在一种特定的设计中，我们将一种新型的、高度光毒性的氯(&=0.6)和一个近红外荧光团(AlexaFluor 750，ex/em 749/775 nm)连接到纳米颗粒上。当被650 nm的激光照射激活时，该纳米试剂表现出极好的光毒性，其LC_(50)为14 nm。初步结果表明，这种纳米颗粒在全身注射和光治疗后，在载脂蛋白E基因敲除(ApoE-/-)小鼠的动脉粥样硬化病变中具有极高的蓄积和治疗效果。现在的挑战是开发一种临床上可行的下一代纳米平台，并确定其在检测和治疗动脉粥样硬化性血管疾病方面的潜在用途。以前的筛选已经确定聚乙烯醇(PVA)是一种非常有前途的包衣材料，并导致制备出既生物稳定又生物兼容的纳米颗粒制剂。拟议研究的总体目标是合成并充分表征一种基于PVA包裹的氧化铁纳米颗粒的新型治疗(治疗和诊断)纳米材料。该纳米材料的体外和体内效果将从成像和治疗功能两个方面进行阐述。在这些研究中，我们还将探讨局灶性巨噬细胞消融在细胞水平上对动脉粥样硬化病变停滞的作用，以及对循环单核细胞的可能调节作用。这些研究的推动力是相信，在一个多功能纳米颗粒中结合诊断和治疗功能有可能彻底改变冠状动脉综合征的预防。 公共卫生相关性：这项研究的总体目标是建立在我们关于动脉粥样硬化性血管病变诊断和治疗中治疗药物的疗效的初步数据的基础上。具体地说，我们将：1)合成和表征一种新的治疗性纳米制剂，2)在小鼠动脉粥样硬化模型中确定其体内疗效，3)研究局部巨噬细胞消融的局部和全身效应。

DESCRIPTION (provided by applicant): A variety of novel nanomaterials have recently been developed with primary in vivo distribution to macrophages and macrophage subtypes. These materials have been used for the diagnosis of diseases where macrophages play a critical role in pathogenesis. For example, we have developed fluorescently labeled dextran-based superparamagnetic iron oxide (magnetofluorescent) nanoparticles detectable by magnetic resonance and optical imaging and have used them for macrophage targeting in lymph nodes, atherosclerosis, rheumatoid arthritis, diabetes and other diseases. Clinical trials with some of these materials are currently ongoing. Macrophages, in particular activated macrophages, are a key component of atherosclerotic vessels and can constitute up to 10-20% of the cells present within the culprit lesions. Macrophages secrete proteolytic enzymes which cause degradation of fibrous caps, promote atherothrombosis, and/or play other key roles in the progressive inflammatory cascade. We originally hypothesized that selective "silencing" of activated macrophages could lead to long lasting therapeutic effects. Thus, we have conjugated light-activatable therapeutic moieties to the nanoparticles. In one specific design we conjugated a novel, highly phototoxic chlorin (& = 0.6), and a near-infrared fluorophore (AlexaFluor 750, ex/em 749/775 nm) to the nanoparticle. When activated by laser irradiation at 650 nm, the nanoagent displays exquisite phototoxicity, with an LC50 of 14 nM. Preliminary results demonstrate superb accumulation and therapeutic efficacy of this nanoparticle in atherosclerotic lesions in apolipoprotein E knockout (ApoE-/-) mice following systemic injection and light treatment. The challenge now is to develop a clinically viable, next-generation nanoplatform and ascertain its potential utility in the detection and treatment of atherosclerotic vascular disease. Prior screens have identified polyvinyl alcohol (PVA) as a highly promising coating material, and results in nanoparticle preparations that are both biostable and biocompatible. The overall goal of the proposed research is to synthesize and fully characterize a novel theranostic (therapeutic and diagnostic) nanomaterial based upon PVA coated iron oxide nanoparticles. The in vitro and in vivo efficacy of the nanomaterial will be elucidated with respect to both the imaging and therapeutic functionalities. Within these studies, we will also explore the role of focal macrophage ablation on the stasis of the atherosclerotic lesions at the cellular level, and possible modulatory effects on circulating monocytes. The impetus for these studies is the belief that the combination of diagnostic and therapeutic functionalities within one multifunctional nanoparticle has the potential to revolutionize the prevention of coronary syndromes. PUBLIC HEALTH RELEVANCE: The overall goal of this research is to build upon our preliminary data with respect to the therapeutic efficacy of a theranostic agent in the diagnosis and treatment of atherosclerotic vasculature. In particular, we will: 1) synthesize and characterize a novel therapeutic nanoagent, 2) determine its in vivo efficacy in a murine model of atherosclerosis, and 3) investigate the local and systemic effects of focal macrophage ablation.