A U.S. research team has released a report showing that embryonic stem cells injected into the brains of Parkinson’s patients have a serious risk of forming tumours.

Steven Goldman and colleagues at the University of Rochester Medical Centre in New York wrote in the journal Nature Medicine that human embryo cells injected into the brains of rats showed signs of forming cancerous cells.

Parkinson’s disease is caused when dopamine-releasing cells die in the brain and scientists have shown that stem cells can be targeted to repair the damaged tissue.

Embryonic cells, however, have proven to yield unpredictable and sometimes-dangerous results.

In the case of Parkinson’s, much progress has been made already with adult stem cells that so far do not show the same propensity as embryonic cells to form tumours or “go wild” and form unpredictable types of tissue.

In the case of Goldman’s research, though, the injected embryonic cells grafted successfully with the area of Parkinson’s damage and the cells began dividing in a way that had the potential to develop into tumours.

Previous experiments with fetal cells have led to some disastrous failures. In August 2003, a similar experiment using cells derived from aborted fetal tissue, a repeat of an earlier attempt, resulted in what researchers involved called “catastrophic” and irreversible side effects. The study, published in the Annals of Neurology, showed that of the 23 Parkinson’s patients who received transplants of aborted fetal tissue, 13 developed irreversible spasmodic movements in their limbs.

This article originally appeared Oct. 23 at LifeSiteNews.com and is reprinted with permission.