The study in the Proceedings of the National Academy of Sciences shows that reprogrammed cells, also called induced pluripotent stem (iPS) cells, when transplanted into the brains of mice and rats transform into neurons. These neurons were seen to improve debilitating symptoms typical of Parkinson’s disease in a rat model.

Pluripotency is the ability to transform into any kind of cell.  But this concept in reprogrammed cells raises some serious questions about the abilities and potential dangers of the cells.

The research team, led by Rudolph Jaenisch at the Whitehead Institute for Biomedical Research at MIT, made the skin cells of a mouse pluripotent by infecting them with a retrovirus carrying four genes. This was a previously developed method for reprogramming cells. 

The researchers showed that they could turn mouse skin cells into functioning neurons in culture. Then they transplanted these neurons into the brains of mice while they were still fetuses.

After the mice grew into early adulthood, the researchers examined the brains and identified the transplanted cells.  The programmed cells had been labeled with a fluorescent marker for identification.

The cells "migrate nicely into the brain and mature in the brain.  They adopt functions of mature neurons,” said Marius Wernig, a postdoctoral fellow at the Whitehead Institute. “This is the first demonstration that re-programmed cells can integrate into the neural system or positively affect neurodegenerative disease,” he added.