Tracking Stem cells with IMAGEtags

描述（由申请人提供）： 迄今为止，大多数真实的时间成像程序已被用于检测体内癌细胞。由于几个原因，这些方法的应用可能不适合干细胞。首先，跟踪系统包括待跟踪的细胞中外源蛋白的表达，所述外源蛋白具有改变干细胞行为（例如增殖、分化和迁移）的潜力。第二，外源蛋白质的产生通常比细胞中其他蛋白质的水平高出许多倍，需要细胞将其能量的很大一部分用于其合成。虽然这对于癌细胞来说不太可能是一个问题，因为癌细胞通常表达非常高水平的己糖激酶和葡萄糖转运蛋白，用于通过糖酵解制造ATP，但干细胞不太健壮，可能会被削弱。为了有效的组织修复，干细胞必须在以前受损的组织区域迁移和增殖，这些区域通常是缺氧和营养耗尽的。 当细胞需要科普不适当的环境时，从不能容易地下调的组成型启动子合成外源蛋白的额外需要将对细胞造成能量负担，并且可能减少可以成功地填充受损组织的细胞的数量。因此，为了标记干细胞，具有不对被成像的细胞施加大的能量负担的系统将是非常有利的。 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，这样它们就可以在体内和真实的时间内被跟踪，而它们的归巢、增殖和分化的潜力不会被标记系统改变。目前的提议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，因此可以通过可用的成像技术在体内跟踪它们。我们称这些标记为“细胞内多适体遗传标签”（IMAGEtags）。所提出的IMAGEtag设计的基本创新是在活细胞中表达适体，其可用于通过非侵入性程序在体内追踪细胞。表达IMAGE标签的细胞将通过与适体结合的浓缩配体来检测。 (End摘要）

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)