Human iPS stem cells mend paralyzed mice

A team at Keio University has used stem cells to cure mice whose hind legs were paralyzed due to spinal cord damage, the researchers reported Wednesday at a Tokyo symposium.

The team transplanted neural stem cells grown from human iPS cells.

Team leader Hideyuki Okano, a physiology professor at Keio, said it is the first time in the world in which the curative effects of "induced pluripotent stem cells," or iPS cells, have been confirmed.

Currently, there is no effective treatment for spinal nerve damage and treatment using iPS cells gives hope of a cure.

"It is valuable that treatment using human iPS cells has proved effective. We want to apply (the results) in a clinical setting as soon as possible," Okano said.

The team generated neural stem cells, which will grow into nerve cells, from human iPS cells produced with a technique developed by Shinya Yamanaka of Kyoto University.

The team transplanted some 500,000 neural stem cells into the damaged spines of 40 mice nine days after their injuries, which is believed to be the most effective time for transplant, according to Okano.

The team used special kinds of mice that do not develop immunological rejections of transplants.

After about a month, 29 mice that survived were able to walk or run.

The other 11 mice died of diseases not related to the experiment, the team said.

Although some scientists worry that the cells could turn malignant during treatment using iPS cells, no cancer has been found among the mice, according to Okano.