Molecular UBM and MRI of Vascular Development.

描述（由申请人提供）： 在过去的十年中，使用基因工程小鼠的研究已经对胚胎血管发育的遗传控制产生了新的见解，这也对我们理解癌症和糖尿病视网膜病变等疾病中的新血管形成产生了重大影响。非侵入性显微成像方法，如超声生物显微镜（UBM）和高分辨率磁共振成像（MRI）可以在这项研究中发挥重要作用，使发育中的小鼠胚胎在子宫内直接可视化。我们率先使用UBM和UBM引导的多普勒超声在正常和突变小鼠胚胎体内解剖和功能性心血管发育。活胚胎的MRI更困难，但几个研究小组已经显示了对比灌注在固定小鼠胚胎血管结构的高分辨率MRI分析中的实用性。这些研究缺乏直接成像分子靶点的能力，以更好地理解基因表达模式并将其与UBM和MRI提供的形态和功能数据相关联。最近的进展表明，细胞特异性血管成像应该是可能的，使用超声和MRI造影剂靶向特定的内皮细胞受体。这种策略可能首先在转基因小鼠中获得成功，这些转基因小鼠从内皮细胞特异性启动子过度表达定义的受体，尽管类似的方法可能使小鼠和男性中内源性受体的未来成像成为可能。靶向超声造影剂具有通过超声介导的转染或声致穿孔增强体内细胞特异性基因递送的额外优点。 具体目标是： 1)建立转铁蛋白受体（Transferrin Receptor，TfR）转基因小鼠。 2)确定声致穿孔在小鼠胚胎心血管系统中的最佳条件。 3)开发和测试TfR特异性造影剂，用于子宫内靶向UBM成像和小鼠胚胎心血管系统的声穿孔。 4)开发和测试用于固定小鼠胚胎靶向血管MRI的TfR特异性造影剂。 该项目开发的方法将为直接分析活小鼠胚胎中的血管发育提供强大的新工具。值得注意的是，这些新的分子成像方法将首次提供检测正常和基因工程小鼠子宫内基因表达的能力。 (End摘要）

DESCRIPTION (provided by applicant): Over the past decade, investigations using genetically-engineered mice have led to new insights into the genetic control of embryonic vascular development, which has also had a major impact on our understanding of neovascularization in diseases such as cancer and diabetic retinopathy. Noninvasive micro-imaging methods such as ultrasound biomicroscopy (UBM) and high-resolution magnetic resonance imaging (MRI) can play an important role in this research, enabling direct in utero visualization of the developing mouse embryo. We have pioneered the use of UBM and UBM-guided Doppler ultrasound for in vivo anatomical and functional cardiovascular development in normal and mutant mouse embryos. MRI of live embryos has been more difficult, but several groups have shown the utility of contrast-perfusion for high resolution MRI analysis of vascular structures in fixed mouse embryos. Lacking in these studies has been the ability to image molecular targets directly, to better understand and correlate gene expression patterns with morphological and functional data provided by UBM and MRI. Recent advances indicate that cell-specific vascular imaging should be possible using ultrasound and MRI contrast agents targeted to specific endothelial cell receptors. This strategy is likely to be successful first in transgenic mice that over-express defined receptors from endothelial cell-specific promoters, although similar approaches may enable future imaging of endogenous receptors in mice and men. Targeted ultrasound contrast agents have the additional advantage of potentiating in vivo cell-specific gene delivery, via ultrasound-mediated transfection, or sonoporation. The specific aims are: 1) To produce transgenic mice over-expressing Transferrin Receptor (TfR) from endothelial promoters. 2) To determine optimal conditions for sonoporation in the mouse embryonic cardiovascular system. 3) To develop and test TfR-specific contrast agents for in utero targeted UBM imaging and sonoporation of the mouse embryonic cardiovascular system. 4) To develop and test TfR-specific contrast agents for targeted vascular MRI in fixed mouse embryos. The approaches developed in this project will provide powerful new tools for direct analysis of vascular development in living mouse embryos. Significantly, these new molecular imaging methods will provide, for the first time, the ability to detect gene expression in utero in normal and genetically-engineered mice. (End of Abstract)