An Activatable Nanoparticle Probe for Molecular Imaging of Protease Activity by Dual Energy CT

用于双能 CT 蛋白酶活性分子成像的可激活纳米颗粒探针

• 批准号: 8909756
• 负责人: Jeffrey R Ashton
• 金额: $ 3.38万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8909756
• 关键词: Area; Arterial Fatty Streak; Atherosclerosis; Biodistribution; Clinical; Contrast Media; Coupled; Detection; Development; Diagnosis; Diagnostic; Disease; Effectiveness; Exhibits; Future; Goals; Gold; Image; In Vitro; Inflammatory; Iodine; Kinetics; Lead; Light; Link; Liposomes; Malignant Neoplasms; Measurement; Measures; Methods; Modality; Modeling; Molecular; Mus; Optics; Pathology; Penetration; Peptide Hydrolases; Peptides; Performance; Primary Neoplasm; Process; Risk; Rupture; Scanning; Signal Transduction; Stratification; Techniques; Testing; Time; Tissues; Toxic effect; United States; Work; X-Ray Computed Tomography; biomaterial compatibility; clinical application; cost; design; diagnosis evaluation; disease diagnosis; imaging probe; improved; in vivo; in vivo imaging; meetings; molecular imaging; mouse model; nanoparticle; nanoprobe; novel; public health relevance; sarcoma; soft tissue; stability testing; tool; tumor

 DESCRIPTION (provided by applicant): Background: X-ray computed tomography (CT) is one of the most useful diagnostic tools for clinicians due to its widespread availability, fast scan times, and low cost. However, molecular imaging with CT is not possible with existing contrast agents, so clinicians must instead rely on other modalities which are more expensive and less readily available. Dual-energy CT (DE CT), a relatively new technique in which two x-ray energies are used for a single scan, can provide valuable information about tissue material composition. This information can potentially be used for molecular imaging if it is coupled with appropriately-designed contrast agents. The goal of this proposal is to develop for the first time an activatable DE CT contrast agent that can be used for the molecular imaging of protease activity. This goal will be met in the following specific aims: Aim 1: Develop and characterize in vitro a protease-cleavable nanoparticle CT contrast agent. Aim 2: Test in vivo performance of cleavable nanoprobes in healthy mice and in a mouse primary sarcoma model using dual energy CT. Methods: In Aim 1, a composite nanoprobe will be developed consisting of iodine-containing liposomes (~120 nm) linked to multiple small (~5 nm) gold nanoparticles by a protease-cleavable peptide. Stability, cleavage, and toxicity of the probe will be studied in vitro In Aim 2, this nanoprobe will undergo biodistribution/kinetics studies in healthy mice and then will be used for in vivo imaging of tumor protease activity in a mouse model of primary soft tissue sarcoma. When this probe is injected in vivo, tumor protease activity will cause cleavage of the peptide linking the gold nanoparticles to the liposome. After cleavage, the small gold nanoparticles will separate from the larger liposomes. Thus, in areas of low proteolytic activity, the DE CT gold and iodine signals should remain overlaid, whereas in areas of high proteolytic activity, the iodine signal should remain high while the gold signal will decrease. The measured ratio of gold to iodine concentration within tissues will be used to evaluate local protease activity. CT measurements of protease activity will be validated by protease-activatable optical probes and by ex vivo tissue analysis. Long-Term Objectives: This study will demonstrate the first use of a CT probe for molecular imaging of protease activity in cancer. This activatable probe has the potential to be used for CT imaging of multiple pathologies which exhibit high protease activity, including cancer, atherosclerosis, and other inflammatory conditions. Development of such a probe will be a significant step forward for non-invasive molecular imaging and has the potential to improve diagnosis and risk stratification for a variety of disease processes.

 描述(申请人提供)：背景：X射线计算机断层扫描(CT)是临床医生最有用的诊断工具之一，因为它广泛可用，扫描时间快，成本低。然而，用现有的造影剂进行CT分子成像是不可能的，所以临床医生必须转而依赖其他更昂贵、更不容易获得的方法。双能量CT(DE CT)是一种相对较新的技术，它使用两个X射线能量进行一次扫描，可以提供关于组织材料组成的有价值的信息。这种信息如果与适当设计的造影剂相结合，可能会被用于分子成像。这项提议的目标是首次开发一种可激活的DE CT造影剂，可用于蛋白酶活性的分子成像。这一目标将在以下具体目标中实现：目标1：开发和体外表征可酶裂解的纳米CT造影剂。目的：用双能CT在健康小鼠和小鼠原发肉瘤模型中测试可裂解纳米探针的体内性能。方法：在目标1中，由含碘脂质体(~120 nm)与多个小的(~5 nm)金纳米颗粒通过可酶切的多肽连接而成的复合纳米探针。Aim 2将在体外研究该探针的稳定性、裂解和毒性。该纳米探针将在健康小鼠体内进行生物分布/动力学研究，然后将用于在原发软组织肉瘤小鼠模型中肿瘤蛋白酶活性的体内成像。当该探针注射到体内时，肿瘤蛋白酶的活性将导致连接金纳米颗粒和脂质体的多肽被裂解。切割后，较小的金纳米颗粒将从较大的脂质体中分离出来。因此，在蛋白分解活性较低的地区，DE CT GOLD和碘信号应该保持重叠，而在蛋白分解活性较高的地区，碘信号应该保持高水平，而金信号将减少。测量的组织内金/碘浓度的比率将被用来评估当地的蛋白酶活性。蛋白酶活性的CT测量将通过可激活的酶光学探头和体外组织分析来验证。长期目标：这项研究将首次使用CT探针对癌症中的蛋白水解酶活性进行分子成像。这种可激活的探针有可能用于多种表现出高蛋白酶活性的病理的CT成像，包括癌症、动脉粥样硬化和其他炎症性疾病。这种探头的开发将是非侵入性分子成像向前迈出的重要一步，并有可能改善各种疾病的诊断和风险分层 流程。