Stretching the limits of stem cells
Stem cells research is a really exciting area of science, and one we often cover on the show. Now new research published in the journal Nature reports an important step forward in our understanding of stem cells, and how we might be able to use them in the future.
This is work from Konrad Hochedlinger at Harvard and his colleagues. They've been trying to understand the difference between cells known as pluripotent stem cells, which can make a limited number of different types of cells, and embryonic stem cells, which can be converted into all the 220 different types of cells in the body. Although these cells both have the same genes, only certain sets of genes can be used in pluripotent stem cells, limiting their potential. And cloning experiments have shown that while a single embryonic stem cell can give rise to a whole new organism, it's never been done with plurpotent stem cells.
They compared mouse embryonic stem cells with genetically identical pluripotent stem cells, to look for key differences in the patterns of gene activity between the two. Importantly, they found that a cluster of genes on chromosome 12 were switched off in the pluripotent stem cells, but not in the embryonic stem cells. This region contains a number of genes that are important for fetal development.
The researchers looked at over 60 different pluripotent cell lines, and found the same genes switched off in the majority of them, suggesting that they are genuinely important. And when they tested whether they could generate cloned mice from the pluripotent cells, they could only make mice from the few pluripotent cells lines where the crucial genes weren't inactivated. In fact, this is thought to be the first time that this has been done using pluripotent stem cells.
This allows researchers to tell whether the cells they're dealing with have the potential to generate all different cell types, or just a limited range. This will become increasingly important in the future, as stem cell technology comes closer to medical applications - doctors will need to be able to choose the best quality stem cells for the job. And it also tells us more about how to change the properties of stem cells - depending on whether we want them to make a wide or restricted range of different cells.