The controversy about adult versus embryonic stem cell research continues to rumble on.

On 27 February 2002, a House of Lords committee gave UK scientists the legal green light to carry out experiments on human embryos. The committee decided that objections were insufficient to outweigh the potential benefits to science. This has angered pro-life and religious groups, which claim that recent breakthroughs in adult stem cell research have removed the need for embryo experiments.

But these adult stem cell studies might have serious potential flaws, according to two reports in Nature. Previously, when researchers found a genetically labelled bone-marrow stem cell in the brain, they took this as an indication that the stem cell had turned into a brain cell. But Professor Austin Smith of Edinburgh University, and senior author of one of the studies, now believes that these stem cells fused with the brain cells to produce cells with double the number of chromosomes, which could have unknown consequences.

“You are not putting in new cells, but fusing with cells that are already there, so the stem cell you have introduced takes on the character of the resident cell,” Smith said (The Daily Telegraph, 14 March 2002). “Our study indicates that calls for a halt to embryonic stem cell research are not scientifically justified”. (BBC News, 13 March 2002).

Professor Smith admits that these results are not the “kiss of death” for adult stem cell research, but stressed that earlier work will need to be re-evaluated.