Molecular Photoacoustic Imaging for Diagnostics and Therapy Monitoring

项目总结 小动物模型是医学研究中强大的发现工具，但牺牲阻止了长期的活体实验 对自然或病理过程的观察。因此，需要一种形态上、功能上、 细胞/分子，定量成像技术，能够纵向可视化的生化和 小动物疾病模型中的药理过程。不幸的是，目前的分子光学成像 这种方法往往会在成像深度和分辨率之间进行不受欢迎的权衡。非侵入性 光声成像(PAI)，它能够同时进行解剖、功能和分子成像 因此，具有高对比度/分辨率的深度病理可视化引起了极大的兴奋 在临床前影像研究人员中。然而，这些最终用户目前缺乏可靠、可重现和 经过验证的分子PAI平台可以补充他们的翻译研究。为了满足这一需求，我们建议 通过靶向造影剂的开发和验证实现PAI的分子敏感性 信号/图像处理算法，允许同时、可重现、定量、纵向和 临床前疾病和治疗反应的分子和生理特征的断层成像 学习。许多可用的分子造影剂缺乏足够的PAI对比度来进行深度成像和/或重叠 具有血红蛋白吸收的光谱特征，使得很难区分靶向探针和 周围的血迹。为了解决这些局限性，我们寻求继续开发一种独特的造影剂 基于装载吲哚青绿(ICG)染料J-聚集体的抗体靶向脂质体。封装 ICG J-聚集体在脂质体隔间中的聚集导致稳定的造影剂(Lipo-JICG)，其提供 体内PAI的非常有利的性质：(I)在~890 nm处有强而窄的吸收，在这里它可以 容易从血红蛋白光谱中分离出来；(Ii)染料聚集介导的PAI信号增强 提高温度梯度和吸光度；(3)实施稳健、半定量PAI的能力 不干扰血氧等重要生理参数成像的分析 饱和度。我们令人信服的初步数据表明，靶向Lipo-JICG提供了令人印象深刻的稳定性、线性 PAI-信号强度和分子特异性。在这项研究计划中，我们将验证分子- 这项前景看好的技术在组织模拟体模、特征明确的细胞培养、 以及卵巢癌的原位模型。在这些研究结束后，我们将可以开始大规模- 制作和最终用户传播的Lipo-JICG和图像处理算法作为一个充分验证的， 分子特定的PAI平台，用于可靠、可重复性和负担得起的临床前成像。虽然不是 这项建议的主要目的，这些研究也为我们的代理的临床翻译提供了基础 由其组成的脂质体、ICG和人源化靶向抗体都已通过FDA的检查 静脉注射。使用，因此减少了安全问题，并提高了未来临床使用的机会。

PROJECT SUMMARY Small-animal models are powerful discovery tools in medical research, but sacrificing prevents long-term, in vivo observation of natural or pathological processes. As such, there is a need for a morphologic, functional, cellular/molecular, and quantitative imaging technique capable of longitudinal visualization of biochemical and pharmacological processes in small-animal disease models. Unfortunately, current molecular optical imaging approaches tend to present an undesirable trade-off between imaging depth and resolution. Non-invasive photoacoustic imaging (PAI), which is capable of simultaneous anatomical, functional, and molecular visualization of pathology with high contrast/resolution at depth, has thus generated significant excitement among preclinical imaging researchers. However, these end-users currently lack a reliable, reproducible, and validated molecular PAI platform to complement their translational research. To address this need, we propose enabling the molecular sensitivity of PAI through the development and validation of targeted contrast agents and signal/image processing algorithms to allow simultaneous, reproducible, quantitative, longitudinal, and tomographic imaging of molecular and physiological signatures of disease and therapy response in preclinical studies. Many available molecular contrast agents lack adequate PAI contrast for deep imaging and/or overlap with spectral features of hemoglobin absorption, making it difficult to differentiate a targeted probe from surrounding blood. To address these limitations, we seek to continue development of a unique contrast agent based on antibody-targeted liposomes loaded with J-aggregates of indocyanine green (ICG) dye. Encapsulation of ICG J-aggregates in a liposomal compartment results in a stable contrast agent (Lipo-JICG), which provides highly advantageous properties for in vivo PAI: (i) a strong, narrow absorbance at ~890 nm, where it can be readily unmixed from hemoglobin spectra; (ii) enhancement of PAI signal due to dye-aggregation-mediated increases in thermal gradients and absorbance; (iii) the ability to implement robust, semi-quantitative PAI analysis that does not interfere with imaging of important physiological parameters such as blood oxygen saturation. Our compelling preliminary data show that targeted Lipo-JICG provides impressive stability, linearity, PAI-signal intensity and molecular specificity. During this research proposal, we will validate the molecular- imaging capabilities of this promising technology in tissue-mimicking phantoms, well-characterized cell cultures, and orthotopic models of ovarian cancer. At the conclusion of these studies, we will be in position to start mass- production and end-user dissemination of Lipo-JICG and image processing algorithms as a fully validated, molecularly specific PAI platform for reliable, reproducible, and affordable preclinical imaging. Although not the principle objective of this proposal, these studies also provide a foundation for clinical translation of our agent as the liposomes, ICG, and humanized-targeted antibodies of which it is composed have all been FDA cleared for i.v. use, therefore reducing safety concerns and improving the chances for future clinical utilization.