Embryonic stem cells repair the brain of rats

Transplantation of human embryonic stem cells could one day restore cognitive abilities impaired by radiotherapy, as suggested by experiments conducted on rats, according to studies published Monday in the United States.

The researchers found that animals with transplanted human embryonic stem cells returned back to their learning capacity and memory to levels considered normal four months after radiotherapy.

In comparison, rats that underwent the same radiation treatment but had not had a transplant had suffered permanent loss of more than 50% of their cognitive functions, according to the study published in The ANNALS of the American Academy of Political and Social Science, dated November 9.

"The results of our research show the first evidence that stem cells may restore brain tissue damaged by radiation of radio-therapy," said Dr. Charles Limoli, a cancer specialist and the lead author of this publication, Professor of Medicine at the University of California, Irvine.

Patients undergoing radiation treatment at a level necessary to reduce the tumor, suffer various degrees of reduced capacity to learn and memorize, which may affect their quality of life.

"The cranial radiation side effects were progressive and debilitating and non-reversible," explains Dr. Limoli. "Any treatment showing a hope to reverse this damage is worth to be researched further," he added.

In this research, human embryonic stem cells were transplanted into rats which had undergone radiotherapy. Stem cells have migrated to an area of the brain known to promote growth of neurons, the brain cells.

Researchers are now trying to determine precisely the mechanism which allowed the improvement of the irradiated brain and put forward two hypotheses. They believe these stem cells could integrate into the tissue to promote their healthy development. But they could also help repair and maintain existing brain cells.

"Further research may allow one day the use of embryonic stem cells to control or eliminate a variety of side effects resulting from radiation therapy," Dr. Limoli said.

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