Tracking Stem cells with IMAGEtags

描述(由申请人提供)： 到目前为止，大多数实时成像程序都被用来检测体内的癌细胞。由于几个原因，这些方法的应用可能不适合干细胞。首先，跟踪系统包括在被跟踪的细胞中表达一种可能改变干细胞行为(如增殖、分化和迁移)的外源蛋白。其次，外源蛋白质的产生通常要达到细胞内其他蛋白质水平的许多倍，这需要细胞将很大一部分能量用于合成。虽然这对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体，通过糖酵解来制造ATP，但干细胞不那么健壮，可能会虚弱。为了有效的组织修复，干细胞必须在先前受损的组织中迁移和增殖，这些组织通常是缺氧和营养耗尽的。 当细胞需要应对不充分的环境时，从不容易下调的构成启动子合成外源蛋白的额外需要将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巨大能量负担的系统将是非常有利的。 这项研究的最终目标是开发一种无害的标记干细胞的方法，以便在体内实时跟踪干细胞，而不会改变标记系统对其归巢、增殖和分化的潜力。目前的提议描述了一种新的核酸结构，这种结构将在细胞中表达，以标记它们，从而可以通过现有的成像技术在体内进行跟踪。我们称这些标记为“细胞内多适配子遗传标记”(IMAGE标记)。提出的IMAGE标签设计的基本创新是在活细胞中表达适体，这种适体可以通过非侵入性程序在体内跟踪细胞。表达IMAGE标签的细胞将通过与适体结合的浓缩配体被检测到。(摘要结束)

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)