Biogenic Gas Nanostructures As Molecular Imaging Reporters For Ultrasound

项目摘要/摘要 超声是世界上应用最广泛的生物医学成像技术之一，因为它与 简单，低成本，能够以高空间和时间分辨率可视化深层组织。然而， 由于缺乏造影剂，超声在分子和细胞成像中一直扮演着很小的角色 与细胞功能的特定方面有关，如基因表达。为了解决这一限制，我们正在 开发第一个声学生物分子--可以用超声波成像的蛋白质。这些构造是 基于气泡-一种来自浮力光合作用微生物的独特的充满气体的蛋白质，我们 2014年被改装为超声波显像剂。自从这一关键的初步发现以来，我们的实验室一直在领导 通过物理、化学和工程技术发展生物分子超声这一新兴领域 气泡的生物学特性使多路成像、细胞靶向和选择性检测成为可能 活着。同时，我们还致力于将编码气泡的基因程序移植到异源细胞中 宿主，最近在与哺乳动物微生物群相关的共生细菌中成功地做到了这一点，而在 在哺乳动物细胞中表达气泡方面取得了初步进展。另外，我们发现， 气泡可以产生可通过超声波擦除的敏感性加权MRI对比剂，提供额外的 读出方式具有独特的优势。在这里，我们建议在这些洞察力的基础上推进气泡 作为靶向纳米造影剂、哺乳动物报告基因和超声功能传感器。这 工作重点将放在长期循环和血管外靶向的工程气泡特性上 通过血液，在哺乳动物细胞中实现气泡作为报告基因的强劲表达， 开发非线性超声脉冲序列以最大限度地提高气泡成像的灵敏度，以及 设计了第一个酶活性声学传感器。这项研究的根本创新之处在于 气泡是第一种生物分子、基因工程和编码的造影剂 超音波。因此，他们有可能以类似的方式改变这种成像方式 荧光蛋白改变了光学显微镜。

PROJECT SUMMARY/ABSTRACT Ultrasound is among the world's most widely used biomedical imaging technologies due to its relative simplicity, low cost and ability to visualize deep tissues with high spatial and temporal resolution. However, ultrasound has historically had a small role in molecular and cellular imaging due to the lack of contrast agents connected to specific aspects of cellular function such as gene expression. To address this limitation, we are developing the first acoustic biomolecules – proteins that can be imaged with ultrasound. These constructs are based on gas vesicles – a unique class of gas-filled proteins from buoyant photosynthetic microbes, which we adapted as imaging agents for ultrasound in 2014. Since this key initial discovery, our laboratory has led the development of the emerging field of biomolecular ultrasound by engineering the physical, chemical and biological properties of gas vesicles to enable multiplexed imaging, cellular targeting and selective detection in vivo. In parallel, we have worked on transplanting the genetic program encoding gas vesicles into heterologous hosts, recently succeeding in doing so in commensal bacteria relevant to the mammalian microbiome, while in parallel making initial progress on expressing gas vesicles in mammalian cells. In addition, we discovered that gas vesicles can produce susceptibility-weighted MRI contrast erasable by ultrasound, providing an additional readout modality with unique advantages. Here we propose to build on these insights to advance gas vesicles as targeted nanoscale contrast agents, mammalian reporter genes and functional sensors for ultrasound. This work will focus on engineering gas vesicle properties for long-term circulation and extravascular targeting through the bloodstream, achieving robust expression of gas vesicles as reporter genes in mammalian cells, developing nonlinear ultrasound pulse sequences to maximize the sensitivity of gas vesicle imaging, and designing the first acoustic sensors of enzyme activity. The fundamental innovation contained in this research is that gas vesicle are the first biomolecular, genetically engineered and encoded contrast agent of any kind for ultrasound. As a result, they have the potential to transform this imaging modality analogously to the way fluorescent proteins transformed optical microscopy.