It does have a certain Humpty-Dumpty feel about it – “When I use a word…  it means just what I choose it to mean neither more nor less”. The US National Institutes of Health is thinking of redefining a human embryonic stem cell (hESC) to make more of them available for Federal funding.

Last year, after President Obama declared that it was time for a new direction in stem cell research in the US, it defined hESCs as cells “derived from the inner cell mass of blastocyst stage human embryos”.  These are 4 to 6 days old and have roughly 100 cells. However, this leaves out hESCs derived from blastomeres, which are only 1 or 2 days old and have only about 8 cells. So the proposed new definition is “pluripotent cells that are derived from early stage human embryos, up to and including the blastocyst stage”.

The reason for the change appears to be to allow Federal funding to flow to Advanced Cell Technology, a company which has derived hESCs from blastomeres. It claims that its technique is even more ethical, as no embryos are destroyed when a cell is removed from a blastomere. (At least IVF doctors say that this is the case when the technique is used in their clinics to test an embryo for genetic defects or its sex.)

 Dr David Prentice, of the Family Research Council, has pointed out that the new rule is more likely to result in the destruction of more embryos. In ACT’s experiments on blastomeres, at least some of them perish. Furthermore, some recent research suggests that removing a single cell does harm an embryo. If this is true, he asks, wouldn’t ACT’s stem cells fall foul of the Dickey Amendment, a Congressional ban on funding destructive embryo research?

Comments on the proposed redefinition close on March 25. Dr Prentice, who is almost alone in making comments in the media, is not impressed: “this redefinition illustrates the willingness of NIH to change the rules to fit their desires for more embryos. Expect more abuses in the future.” ~ Los Angeles Times, Feb 19