Scientists at the Whitehead institute for Biomedical Research in Massachusetts have successfully transformed human skins cells into stem cells that could be used to study and find treatments for Parkinson's disease. At the same time they removed the viruses usually used in the process, thereby minimising the risk of cancer. The findings are published in the 6 March edition of the journal Cell.
The Whitehead team used a virus to transfer specific genes into the DNA of skin cells from people with Parkinson's. The genes caused the adult cells to reprogram as induced pluripotent stem (iPS) cells, which can divide into any cell of the human body. They then used an enzyme to trim out the genetic material from the virus, which has been linked to an increased risk of cancer.
Since 2006 scientists have been reprogramming adult cells into iPS cells using viruses to transfer genes into the cells' DNA. But this study marks the first time researchers have successfully removed the reprogramming genes with the iPS cells retaining their embryonic stem cell-like properties.
The Whitehead team then used the iPS cells to derive specialised neurons that release dopamine. This chemical helps people perform smooth and coordinated movements and is lacking in people with Parkinson's because the neurons that produce it are depleted. The dopamine-releasing neurons may be used to study the disease, screen for new drugs and eventually they could lead to the creation of cellular therapies.
Dr Rudolf Jaenisch, Professor of Biology at the Whitehead Institute, said: 'Other labs have reprogrammed mouse cells and removed the reprogramming genes, but it was incredibly inefficient, and they couldn't get it to work in human cells... We have done it much more efficiently, in human cells, and made reprogrammed, gene-free cells'.
Although the initial results show great potential, Jaenisch acknowledges that there is lots more work to be done: 'The next step is to use these iPS-derived cells as disease models, and that's a high bar, a real challenge', he said.
This discovery comes in the same week as researchers found a way of ferrying genes into human cells without the use of a virus. Two teams from the University of Toronto and the Medical Research Council Centre for Regenerative Medicine at the University of Edinburgh used a technique called electroporation to insert genes into cells through pores. The genes were later removed making the cells entirely free of foreign DNA.