Molecular UBM and MRI of Vascular Development.

描述(由申请人提供)： 在过去的十年里，使用基因工程小鼠的研究带来了对胚胎血管发育的基因控制的新见解，这也对我们对癌症和糖尿病视网膜病变等疾病中的新生血管的理解产生了重大影响。超声生物显微镜(UBM)和高分辨率磁共振成像(MRI)等非侵入性微成像方法可以在这项研究中发挥重要作用，使发育中的小鼠胚胎能够在宫内直接可视化。我们已经率先使用UBM和UBM引导的多普勒超声在正常和突变小鼠胚胎中进行体内解剖和功能心血管发育。活体胚胎的核磁共振成像一直比较困难，但有几个小组已经证明了对比剂-灌注法在分析固定小鼠胚胎血管结构的高分辨率核磁共振成像中的作用。这些研究缺乏直接成像分子靶标的能力，无法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，使用针对特定内皮细胞受体的超声和磁共振造影剂进行细胞特异性血管成像是可能的。这一策略很可能首先在过度表达内皮细胞特异性启动子的特定受体的转基因小鼠中获得成功，尽管类似的方法可能会在未来对小鼠和人的内源性受体进行成像。靶向超声造影剂还有一个额外的优势，那就是通过超声介导的基因转染法或声孔法，增强体内细胞特异性基因的传递。 具体目标是： 1)获得内皮启动子高表达转铁蛋白受体(TFR)的转基因小鼠。 2)确定在小鼠胚胎心血管系统中进行声学修饰的最佳条件。 3)研制和测试TFR特异性造影剂，用于小鼠胚胎心血管系统的宫内靶向UBM成像和声学定位。 4)研制和测试TFR特异性造影剂，用于固定小鼠胚胎的靶向血管磁共振成像。 该项目开发的方法将为直接分析活鼠胚胎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。(摘要结束)

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)