Lead author Marius Wernig of the Whitehead Institute for Biomedical Research in Cambridge, Mass., said it is the first demonstration that "reprogrammed cells can integrate into the neural system or positively affect neurodegenerative disease."

The findings are published in the online early edition of the journal PNAS.

Researchers in Rudolf Jaenisch's laboratory showed that the brains of mice with a human sickle-cell anemia disease trait could be successfully treated with skin cells that had been reprogrammed to an embryonic stem cell-like state, Whitehead said Monday in a release.

The researchers, in collaboration with Harvard Medical School, also found that in vitro reprogrammed cells can in principle be used to treat Parkinson's disease.

"It's a proof of principle experiment that argues, yes, these cells may have the therapeutic promise that people ascribe to them," Jaenisch said in a statement.