Carbon-nanotube-based nanocomposites for siRNA delivery into human embryonic stem cells

科学家们经常希望在试管中培养人体细胞，实际上，他们最终希望获得一种特殊类型的细胞，称为干细胞，并使它们完全在体外生长成完整的器官。这些器官可以用来替代衰竭的器官，从而挽救生命。然而，这是非常困难的，原因之一是我们无法控制干细胞。它们按照自己的遗传程序生长成我们不想要的细胞类型。所以我们需要控制这个遗传程序，以便使干细胞产生我们想要的器官。控制这种遗传程序的一种方法是通过所谓的RNA干扰。基因被制成RNA分子，RNA分子又被制成蛋白质。RNA干扰是对基因与蛋白质之间的RNA中间体进行干扰，但将RNA分子导入干细胞进行RNA干扰是一个困难的过程。RNA分子通常停留在细胞外。在这里，我们将使用RNA、脂肪分子和碳纳米管的复合物将RNA输送到干细胞中。碳纳米管是一种长的碳管，直径只有十亿分之几米（人类的头发是1000多倍宽），但比这长得多，因此得名管。这些复合材料是微观的，只有千分之一毫米左右，或100纳米。这就是为什么它们被称为纳米复合材料。其他类型的细胞已经显示出容易吸收这些复合物及其RNA货物。所以我们将在干细胞上尝试这些复合材料，看看我们是否可以控制细胞的遗传程序。

Scientists often wish to grow human cells in test-tubes, indeed ultimately they hope to take a special type of cell, called a stem cell, and make them grow into complete organs completely outside of the body. These organs could then be used to replace failed organs and so save lives. However, this is very difficult, and one of the reasons is that we cannot control stem cells. They follow their own genetic program and grow into types of cells that we don't want. So we need to control this genetic program in order to make the stem cells produce the organ we desire. One way of controlling this genetic program is via what is called RNA interference . Genes are made into RNA molecules which in turn are made into proteins. RNA inteference interfers with the RNA intermediate between genes and their proteins.However, introducing the RNA molecules into a stem cell to do RNA inteference is difficult. Often the RNA molecule stays outside the cell. Here we will use composites of RNA, fatty molecules and carbon nanotubes to deliver the RNA into stem cells. Carbon nanotubes are long tubes of carbon that are only a few billionths of a metre across (a human hair is more than a 1000 times wider) but are much longer than this, hence the name tube. These composites are microscopic, only around a tenth of a thousandth of a millimetre across, or 100 nanometres. This is why they are called nano-composites. Other types of cell have been shown to readily take up these composites with their RNA cargo. So we will try these composites on stem cells to see if we can control the cells' genetic program.