Contrast agents for high-sensitivity ultrasound molecular imaging of tumor angiog

描述（由申请人提供）：分子成像技术在临床前研究方面具有强大的潜力，主要用于药物发现和癌症研究领域的基础科学。特别是，高频超声是一种强大的成像方式，用于表型和监测对实验治疗的反应。与其他分子成像技术相比，超声具有便携、不利用电离辐射、成本低、空间和时间分辨率高等优点。然而，用于小动物超声成像的高效分子造影剂在高成像频率（15-40 MHz）下有效的发展极大地限制了该技术的应用。虽然用于临床前成像的超声造影剂在市场上是可用的，但这些产品的有限性能限制了这项技术的应用。被称为微泡（MB）的气体封装颗粒被用作超声造影剂，最近的研究已经确定MB直径是MB活性的关键决定因素，是成像频率的函数。然而，目前的甲基丙烯酸酯配方往往是高度多分散的，目前还没有高通量的技术来制造适合商业规模生产的受控直径的甲基丙烯酸酯。我们建议开发一种低成本的方法来生产针对VEGFR2的直径可控的MB。Targeson公司开发了一种脂质包裹的MB，它含有一种对抗VEGFR2的配体，这种药物在低超声频率下用于肿瘤血管生成成像。我们假设，通过在不同强度的有机溶剂中孵育，控制脂质MB壳的溶解，将使我们能够减小该剂的平均直径。此外，我们已经开发了一种强大的重力分离方法，使我们能够根据不同的浮力对MB进行大小排序。我们建议将这两种方法结合起来，产生一系列不同直径的vegfr2靶向MB群体。我们将使用一种新型的vegfr2包覆超声流模和高频超声扫描仪筛选这些MB制剂的体外成像效果。然后，我们将与一家商业伙伴合作，测试我们的大小分类靶向MB在前列腺癌和膀胱癌两种小鼠模型中监测肿瘤发展的能力。

DESCRIPTION (provided by applicant): Molecular imaging techniques have strong potential in the setting of preclinical research, primarily for drug discovery and basic science in the field of cancer research. In particular, high-frequency ultrasound is a powerful imaging modality for phenotyping and monitoring the response to experimental therapy. Relative to other molecular imaging techniques, ultrasound is portable, does not utilize ionizing radiation, is low cost, and has high spatial and temporal resolution. However, the development of efficacious molecular contrast agents that are active at the high imaging frequencies (15-40 MHz) used in small animal ultrasound imaging has greatly limited the application of this technique. Although ultrasound contrast agents for preclinical imaging are commercially available, the limited performance of these products has restricted the utility of this technique. Gas-encapsulated particles known as microbubbles (MB) are used as contrast agents for ultrasound, and recent research has identified MB diameter as the key determinant for MB activity as a function of imaging frequency. However, current MB formulations tend to be highly polydisperse, and there are currently no high- throughput techniques for manufacturing MB at controlled diameters suitable for commercial-scale manufacture. We propose to develop a low-cost method of producing MB of controlled diameter targeted to VEGFR2. Targeson has developed a lipid-encapsulated MB bearing a ligand against VEGFR2, and this agent has shown utility for imaging tumor angiogenesis at low ultrasound frequencies. We hypothesize that controlled dissolution of the lipid MB shell, by incubation in varying strength organic solvents, will enable us to reduce the mean diameter of this agent. Additionally, we have developed a robust method of gravitational separation that allows us to size-sort MB based upon differential buoyancy. We propose to combine these two methods to produce a series of VEGFR2-targeted MB populations of varying diameter. We will screen these MB preparations for imaging efficacy in vitro using a novel VEGFR2-coated ultrasound flow phantom and a high- frequency ultrasound scanner. We will then work with a commercial partner to test the ability of our size-sorted targeted MB to monitor tumor development in two mouse models of prostate and bladder cancer. PUBLIC HEALTH RELEVANCE: Molecular imaging can enable significant cost and time savings in basic science and drug discovery research. In particular, ultrasound molecular imaging has shown promise as a low-cost, high-throughput modality for imaging molecular markers of angiogenesis in a cancer setting. However, sensitive molecular contrast agents are not available for use at the high ultrasound imaging frequencies typically used for small animal cancer models. We propose to develop an ultrasound contrast agent that is precisely tuned to produce a reproducible and strong ultrasound contrast signal for use with small animal imaging in the preclinical research setting. Success in this project will enable routine use of ultrasound in the molecular imaging field and potentially increase the throughput and efficiency of cancer research.