A boy who had fetal stem cells injected into his brain to try to stop a fatal illness later developed dangerous tumours, doctors report.
The case is a reminder to many who are searching desperately for cures to devastating conditions that stem cell therapies are unproven and still in the experimental stage.
The Israeli boy suffered from a rare but fatal genetic disease called ataxia telangiectasia, or A-T, which causes an area of the brain to degenerate, gradually robbing patients of movement. The disease is fatal and most patients die in their teens.
His family, desperate for a cure, took him in 2001 to a clinic in Moscow to see if doctors there could stop the condition. The doctors injected neural stem cells from fetuses into the boy's brain and spinal cord. He received two more treatments, two and four years later.
Not only did the treatments fail to slow the boy's disease, but about a year after his final treatment, he began complaining of severe headaches.
An MRI at a Tel Aviv hospital revealed a growth pushing on the boy's brain stem and a second on his spinal cord. Surgeons were able to remove the spinal cord mass but the brain tumour remains, though it is growing only very slowly.
Doctors decided to find out whether the tumours were the results of the boy's A-T or the stem cell therapy.
A Tel Aviv University team tested the tissue from the spinal cord growth and concluded the tumours were the results of the stem cell therapy. Among other evidence, they found that some of the tumour cells were female and came from at least two donors. As well, the cells had two normal copies of the gene that causes A-T.
This case is thought to be the first of tumour development in a human following fetal stem cell therapy, though similar findings have been made when embryonic stem cells were injected into rats.
The doctors think that the boy's A-T may itself have allowed the tumours to develop, since patients often have an impaired immune system which would normally help reject tumour cells.
The lead researcher, Dr. Ninette Amariglio of Sheba Medical Center in Tel Aviv, also suspects that using stem cells from multiple fetuses that also were mixed with growth-spurring compounds "may have created a high-risk situation where abnormal growth of more than one cell occurred," her team wrote.
She stressed the need for caution in stem cell therapy and urged better research to "maximize the potential benefits of regenerative medicine while minimizing the risks."
But, the authors conclude that their findings "do not imply that the research in stem cell therapeutics should be abandoned."
Stem cells have the potential to become any kind of cell. Because neural cells cannot be replaced once they become damaged or diseased, the hope is that stem cells can be used to re-grow brain and spinal tissue and thus treat conditions such as Parkinson's and spinal cord injuries.
Reports suggest that U.S. President Barack Obama will re-instate federal funding for embryonic stem cell research soon, after former President George W. Bush, greatly limited the use of federal dollars for such research.
