Fewer stem cells available than originally thought

Elias Zerhouni, director of the US National Institutes of Health (NIH) has confirmed in last week's edition of the journal Science that only 11 human embryonic stem cell (ES cell) lines are available for use by US researchers. This is significantly fewer than the number originally stated by the NIH.

On 9 August 2001, President George W Bush announced that federally-funded scientists in the US could only work on ES cell lines already in existence before that date. Research that would cause the destruction of any further embryos for research would not be permitted. According to the NIH, by the end of 2001 there were more than 70 ES cell lines available worldwide to be used by federally-funded US researchers.

But, ever since Bush's announcement, scientists have been challenging the actual number of useful ES cell lines. At a conference in Canada last year, scientists told delegates that fewer than half of the ES cell lines authorised for use by President Bush would 'turn out to be viable in practice'. Last September, some US scientists complained to the Senate that access to the ES cell lines that were suitable was problematic, saying that this was mainly because of financial reasons and restrictions placed on their export and use by some of the countries where they are held.

Zerhouni, in the Science article that reviews the NIH's initiatives and research agenda on stem cells, now says that the number of ES cell lines originally estimated was 'optimistic', commenting that they were in 'early stages of development' and were not ready for use. To overcome the problem, the NIH had issued grants to develop the stem cell lines, resulting in the 11 which are now available for research. The announcement has led to more calls for research restrictions be lifted. Science editor-in-chief, Donald Kennedy, said in an editorial accompanying Zerhouni's article that 'it is plainly not sound policy to retain the current restrictions', adding that 'comfort might be taken from the situation in the United Kingdom, where stem cell research proceeds apace with the blessing  of a friendly government. Unless US policy changes, more cell biologists here may decide it's so friendly they might go and work there'.