A research team at Stanford University School of Medicine, US, has for the first time successfully transformed mouse skin cells directly into neurons. They achieved this by infecting the skin cells with a genetically modified virus that inserts three different genes into the cells' DNA. It was previously thought that only embryonic stem cells and adult stem cells had the ability to be 'rewound' into a state where they could be stimulated to grow into a different type of cell.
'This study is a huge leap forward', said Irving Weissman, director of Stanford's Institute for Stem Cell Biology and Regenerative Medicine. 'Finally we may be able to capture and study conditions like Parkinson's and Alzheimer's or heritable mental diseases in the laboratory dish for the first time'.
The breakthrough will please critics of stem cell research since embryos and embryonic stem cells are not involved in the process at any stage. After the scientists infected the skin cells with three of a possible 19 genes, known to have an effect on mouse cell differentiation, it took less than a week for 20 percent of the cells to turn into fully functioning neurons. 'We actively and directly induced one cell type to become a completely different cell type', said lead author Marius Wernig, assistant professor of pathology and a member of Stratford's Institute for Stem Cell Biology and Regenerative Medicine. 'These are fully functioning neurons... [which] can do all the things that neurons in the brain do'.
Despite being undertaken using mouse cells, the research, published in the journal Nature, could revolutionise the way degenerative conditions are treated in humans. A patient's own skin cells could be turned into a limitless supply of the neurons they need, or any other type of cell such as blood or bone marrow.
The 'induced neuronal cells', as they were dubbed by The Daily Mail newspaper, are much easier to achieve than the induced pluripotent stem cell (iPS cell) method developed by Japanese researcher Shinya Yamanaka of Kyoto University. In 2006, Yamanaka introduced a way to revert ordinary skin cells to pluripotent stem cells, then re-programme them to grow into another type of cell. The Stanford method skips out the time-consuming intermediate stage involved in the iPS process. 'We were very surprised by both the timing and the efficiency', said Weissman, 'this is much more straight forward than going through iPS cells, and it is very likely to be a very viable alternative'.
Another advantage of skipping out the iPS stage is that such cells are known to promote cancers, whereas the cells created by the Stanford team do not go through a 'tumourigenic' phase, noted Professor Jack Price, a neurobiologist at King's College London.