Detection of micrometastasis using a dual-ligand nanoparticle

描述(申请人提供)：绝大多数癌症死亡是由于转移性疾病。虽然有效的干预措施(如手术、放射治疗)在很大程度上依赖于我们在早期阶段发现播散性疾病的能力，但对隐藏在大量正常细胞中的微转移进行成像是一个独特的挑战。我们试图设计一种双配体纳米颗粒，能够“感应”与肿瘤转移相关的内皮细胞。通过选择两种合适的化学特异性，双配体策略既可以协同放大纳米颗粒靶向表达两种受体的微转移瘤，又可以检测只表达一种受体的转移性肿瘤，否则使用单配体策略将无法检测到这一点。我们的中心假设是，双配体纳米颗粒与血管靶向策略相结合，提供了高度敏感和特异性识别微转移的可能性增加。这种纳米颗粒由氧化铁纳米球化学连接成一个线性纳米链组成。我们假设，双配体策略不仅将增强对表达两种受体的区域的靶向性，而且还将“捕获”仅两种受体中的一种主要表达的转移区域。由于纳米颗粒的形状和大小决定了它们的边际和附着到血管床上，我们还假设纳米链的纵横比和整体尺寸可以优化，从而早期和准确地检测转移疾病。我们将通过以下具体目标来验证我们的假设：具体目标1：优化双配体纳米链的设计，以在体外微循环的流动条件下执行血管靶向。我们试图根据两个靶向多肽的长度、宽度和密度来优化纳米链的设计。纳米链的边际化和靶向亲和力将在以不同流速种植内皮细胞和癌细胞的微通道网络中进行评估。具体目的2：检测双配体纳米链对小鼠4T1乳腺肿瘤模型微转移微环境的识别能力。我们试图通过使用荧光分子断层成像定量评估体内转移瘤中荧光标记的纳米链的累积来优化成像的剂量和时间框架。具体目标3：用MRI检测双配体纳米链检测转移的准确性。纳米链增强的磁共振成像将通过分析医生对转移的感知来进行评估。在这项盲目研究中，放射科医生将读取健康和携带肿瘤的动物的磁共振图像，以评估诊断的准确性。作为拟议工作的案例研究，选择了检测肝和肺的三阴性乳腺癌转移，因为这种癌症亚型转移率很高，而且是致命的。然而，这项技术可以用于许多类型的癌症，因为肝和肺是常见的转移部位。

DESCRIPTION (provided by applicant): The vast majority of cancer deaths are due to metastatic disease. While effective interventions (e.g. surgery, radiation) strongly depend on our ability to detect disseminated disease at an early stage, imaging micrometastases hidden in a large population of normal cells presents a unique challenge. We seek to design a dual-ligand nanoparticle capable of 'sensing' the endothelium associated with a metastasis. By selecting two appropriate chemical specificities, a dual-ligand strategy can provide both synergistic amplification of nanoparticle targeting to micrometastases expressing both receptors but also detection of metastatic tumors expressing only one receptor that would be otherwise missed using a single-ligand strategy. Our central hypothesis is that a dual-ligand nanoparticle coupled with a vascular targeting strategy offer an increased likelihood of highly sensitive and specific recognition of micrometastasis. The nanoparticle is comprised of iron oxide nanospheres chemically linked into a linear nanochain. We hypothesize that the dual- ligand strategy will not only enhance the targeting specificity towards regions that express both receptors, but also 'capture' metastatic regions in which only one of the two receptors is predominantly expressed. Since the shape and size of nanoparticles govern their margination and attachment to the vascular bed, we also hypothesize that the aspect ratio and overall dimensions of the nanochain can be optimized, resulting in early and accurate detection of metastatic disease. We will test our hypotheses with the following Specific Aims: Specific Aim 1: Optimize the design of dual-ligand nanochains to perform vascular targeting under flow conditions of the microcirculation in vitro. We seek to optimize the design of nanochains in terms of their length, width and density of the two targeting peptides. The margination and targeting avidity of the nanochains will be evaluated in microchannel networks seeded with endothelial and cancer cells at different flow rates. Specific Aim 2: Test the ability of the dual-ligand nanochains to recognize the microenvironment of micrometastasis in the 4T1 mammary tumor model in mice. We seek to optimize the dose and timeframe for imaging by quantitatively assessing the accumulation of fluorescently labeled nanochains in metastases in vivo using fluorescence molecular tomography. Specific Aim 3: Test the accuracy of the dual-ligand nanochains to detect metastases using MRI. Nanochain- enhanced MRI will be assessed using an analysis of physician perception of metastases. In this blinded study, radiologists will read MR images of healthy and tumor-bearing animals to estimate the diagnostic accuracy. As a case study for the proposed work, detection of triple-negative breast cancer metastases in the liver and lungs was selected, because this cancer subtype is highly metastatic and deadly. However, this technology can be used for many types of cancer, since liver and lungs are common metastatic sites.