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

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.