Activated nano-sized MR contrast agents for imaging of tumor proteolytic activity

用于肿瘤蛋白水解活性成像的活化纳米级磁共振造影剂

• 批准号: 7739994
• 负责人: Dmitri Artemov
• 金额: $ 18.04万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7739994
• 关键词: Acidosis; Affinity; Area; Binding; Biodistribution; Biological Models; Biological Process; Blood Vessels; Blood capillaries; Breast Cancer Cell; Breast Cancer Model; Cell model; Chemicals; Clinic; Clinical; Complex; Contrast Media; Coupled; Development; Diffuse; Diffusion; Digestion; Disease; Dissociation; Drug Kinetics; Electron Microscopy; Elements; Environment; Environmental Risk Factor; Enzymes; Epitopes; Event; Fresh Tissue; Functional Imaging; Gadolinium; Gel; Human; Hypoxia; Image; Imaging technology; In Vitro; Label; Left; MCF7 cell; Magnetic Resonance Imaging; Malignant Neoplasms; Mass Spectrum Analysis; Matrilysin; Matrix Metalloproteinases; Measures; Methods; Molecular; Molecular Weight; Monitor; Nanotechnology; Pattern; Peptide Hydrolases; Peptides; Phagocytes; Plasma; Pre-Clinical Model; Property; Relaxation; Research; Resolution; Route; Scanning; Screening for cancer; Serum Albumin; Signal Transduction; Site; Slice; System; Techniques; Technology; Testing; Tissues; Translations; Vascular Permeabilities; Weight; Xenograft procedure; base; blood perfusion; capillary; density; design; imaging modality; improved; in vivo; interest; iron oxide; light scattering; malignant breast neoplasm; molecular imaging; nanoparticle; nanoscale; nanosized; novel; optical imaging; particle; polymerization; pre-clinical; prognostic; public health relevance; response; soft tissue; tumor; uptake

DESCRIPTION (provided by applicant): Contrast agents activated by biological processes can be extremely useful for functional imaging of various diseases including cancer, which is typically characterized by unique microenvironment with increased concentration of proteolytic enzymes, hypoxia, and acidosis. This concept has been successfully applied for NIR optical imaging, however it remains an elusive technology for MRI, although several methods had recently been explored including activated chelating compounds for Gd and clustering of SPIO nanoparticles to increase T2 relaxivity. In this application, we will develop a novel class of activated contrast agent for MR imaging using combination of superparamegnetic iron-oxide nanoparticles (SPIO) and multiple Gd groups. When both components are localized in close proximity the resulting complex will produce strong negative T2 contrast in T1/T2-weighted MRI due to high T2 relaxivity of SPIO particles. Upon dissociation of the complex, small Gd groups will diffuse away from the SPIO core and generate positive T1 MR contrast in areas within the diffusion range of Gd but outside the diffusion range of the relatively immobile SPIO nanoparticle. Activated MR imaging agent will be synthesized using an SPIO core, matrix metalloproteinase (MMP-7) and broad-spectrum (FS-1) MMP- specific cleavable peptide linkers, and gadolinium chelates. The constructs will be characterized with DLS, EM, and element analysis by ICP-MS techniques. Proof-of-principle studies of the probe activation will be performed in a model, cell free gel system and in cultured breast cancer cells in vitro. Activation of the MR contrast agents will also be studied in preclinical models of human breast cancer. For biodistribution studies agents will be additionally labeled with multicolor fluorescent tags for SPIO and the leaving Gd group respectively. Biodistribution of the intact agent and its components will be measured using optical imaging of fluorescently labeled CA in fresh tissue sections and histological slices. A novel class of activated MR contrast agents that dramatically changes signal enhancement pattern from negative contrast enhancement (signal loss) to positive (increased signal) upon activation by proteolytic breast cancer associated MMP enzymes can provide noninvasive assessment of proteolytic activity in breast cancers. This is an important prognostic parameter as tumor aggressiveness and metastatic potential strongly correlate with the expression of proteinases. The agent consists of components that are currently approved for clinical use and therefore there are good chances for rapid translation of this imaging nanotechnology to clinic. PUBLIC HEALTH RELEVANCE: MR imaging provides an outstanding spatial resolution and soft tissue contrast, however, its ability to probe subtle features of chemical environment of a tumor is currently limited due to the lack of sensitive imaging contrast agents. In this application, we will use advances in nanotechnology to develop a novel class of MR contrast agents which will be specifically activated within the tumor microenvironment by tumor associated proteolytic enzymes and will provide significant enhancement of the tumor in MR images. These nanoscale activated MR contrast agents can improve existing imaging technology for early cancer detection and/or for noninvasive monitoring of tumor response to therapy.

描述（由申请人提供）：由生物过程激活的对比剂对于包括癌症在内的各种疾病的功能成像非常有用，包括癌症的功能成像，通常以独特的微环境为特征，蛋白水解酶，低氧和酸中毒的浓度增加。该概念已成功地用于NIR光学成像，但是它仍然是MRI的难以捉摸的技术，尽管最近探索了几种方法，包括用于GD的活化螯合化合物和SPIO纳米颗粒的聚类以提高T2松弛性。在此应用中，我们将使用超级发现的铁 - 氧化纳米颗粒（SPIO）和多个GD组的组合开发一种新型的激活对比剂，用于MR成像。当两个组件都位于近距离近端时，由于SPIO颗粒的高T2松弛性，所产生的复合物将在T1/T2加权MRI中产生强大的T2对比度。复合物解离后，小型GD组将从SPIO核心扩散，并在GD扩散范围内的区域产生正t1 MR对比度，但在相对不动的SPIO纳米颗粒的扩散范围之外。活化的MR成像剂将使用SPIO核，基质金属蛋白酶（MMP-7）和宽光谱（FS-1）MMP-特异性可裂解的肽接头和螯合物合成。构造将以ICP-MS技术的DLS，EM和元素分析来表征。探针激活的原则研究将在模型，无细胞凝胶系统和体外培养的乳腺癌细胞中进行。在人类乳腺癌的临床前模型中，还将研究MR对比剂的激活。对于生物分布，研究代理将分别用SPIO和离开GD组的多色荧光标签标记。完整剂及其成分的生物分布将使用在新鲜组织切片和组织学切片中荧光标记的Ca进行光学成像进行测量。一类新型的激活的MR对比剂剂将信号增强模式从负造影剂增强（信号丢失）变为正面（信号增加）到蛋白水解乳腺癌相关的MMP酶激活后的阳性（信号增加），可以提供乳腺癌中蛋白水解活性的非侵袭性评估。这是一个重要的预后参数，因为肿瘤侵袭性和转移潜力与蛋白酶的表达密切相关。该代理由目前批准用于临床使用的组件组成，因此有很大的机会将这种成像纳米技术快速转换为诊所。 公共卫生相关性：MR成像提供了出色的空间分辨率和软组织对比度，但是，由于缺乏敏感的成像对比剂，目前，目前探测肿瘤化学环境的微妙特征的能力受到限制。在此应用中，我们将使用纳米技术的进步来开发一类新的MR造影剂剂，该药物将通过肿瘤微环境在肿瘤微环境中特异性激活，并将在MR图像中可显着增强肿瘤。这些纳米级激活的MR对比剂可以改善现有的成像技术，以早期癌症检测和/或无创监测肿瘤对治疗的反应。