Tracking Stem cells with IMAGEtags

描述（由申请人提供）： 迄今为止，大多数实时成像程序已用于检测体内癌细胞。由于多种原因，这些方法的应用可能不适合干细胞。首先，追踪系统包括待追踪细胞中外源蛋白的表达，该外源蛋白有可能改变干细胞的行为，如增殖、分化和迁移。其次，外源蛋白质的产生通常要达到细胞中其他蛋白质水平的许多倍，需要细胞将很大一部分能量用于其合成。虽然这对于通常表达非常高水平的己糖激酶和葡萄糖转运蛋白以通过糖酵解产生 ATP 的癌细胞来说不太可能是问题，但干细胞的活力较差，可能会变得虚弱。为了有效地修复组织，干​​细胞必须在先前受损的组织区域迁移和增殖，这些区域通常缺氧且营养匮乏。 当细胞需要应对不适当的环境时，额外需要从不易下调的组成型启动子合成外源蛋白，这会给细胞带来能量负担，并可能减少能够成功填充受损组织的细胞数量。因此，对于标记干细胞来说，拥有一个不会给正在成像的细胞带来大量能量负担的系统将具有很大的优势。 这里提出的研究的最终目标是开发一种无害的标记干细胞的方法，以便可以在体内实时跟踪它们，而不会因为标记系统而改变它们的归巢、增殖和分化潜力。目前的提案描述了一种新的核酸结构，该结构将在细胞中表达以标记它们，以便可以通过可用的成像技术在体内追踪它们。我们将这些标记称为“细胞内多适体遗传标签”(IMAGEtags)。所提出的 IMAGEtag 设计的基本创新是适体在活细胞中的表达，可用于通过非侵入性程序追踪体内细胞。表达 IMAGEtags 的细胞将通过与适体结合的浓缩配体进行检测。 （摘要完）

DESCRIPTION (provided by applicant): To-date most real time imaging procedures have been used to detect cancer cells in vivo. The application of these methods may not be appropriate for stem cells for several reasons. First, the tracking systems include the expression in the cells to be tracked of a foreign protein that has the potential of altering stem cell behavior such as proliferation, differentiation, and migration. Second, the production of the foreign protein, often to reach many fold over the levels of other proteins in the cell, requires that the cell devote a significant portion of its energy to its synthesis. Although this is not likely to be a problem for cancer cells which generally express very high levels of hexokinase and glucose transporters for making ATP by glycolysis, stem cells are less robust and could be debilitated. For effective tissue repair, stem cells must migrate and proliferate in regions of previously damaged tissues that are often hypoxic and nutrient depleted. The additional need to synthesize a foreign protein from a constitutive promoter that cannot readily be down regulated will place an energy burden on the cells when they need to cope with an inadequate environment and may decrease the number of cells that can successfully populate the damaged tissue. Consequently, for marking stem cells, it would be of great advantage to have a system that does not place a large energy burden on the cells that are being imaged. The ultimate goal of the research proposed here is to develop an innocuous means of marking stem cells so that they can be tracked in vivo and in real time without their potential for homing, proliferation and differentiation being altered by the marking system. The current proposal describes a novel nucleic acid structure that will be expressed in cells to mark them so they can be tracked in vivo by available imaging technology. We call the markers "Intracellular MultiAptamer Genetic Tags" (IMAGEtags). The basic innovation in the proposed IMAGEtag design is the expression in living cells of aptamers that can be used to track the cells in vivo by a noninvasive procedure. Cells that express IMAGEtags will be detected by virtue of the concentrated ligands bound to the aptamers. (End of Abstract)