Wednesday, August 23, 2006
New technique for deriving embryonic stem cells that doesn't destroy the embryo
An on-line letter (1st paragraph only) at the journal Nature (requires subscription) describes the technique, as do articles posted this afternoon to the web sites of the New York Times and the Wall Street Journal (requires subscription). Researchers at Advanced Cell Technology report success borrowing the technique used for pre-implantation genetic diagnosis ("PGD") of embryos created at in vitro fertilization centers. The technique takes the fertilized egg at the point that it is an 8-celled organism. The cells are called blastomeres, and PGD removes one blastomere for genetic testing and screening. Now 10 years old, PGD produces no discernible harm to the remaining 7-cell organism, which appears capable of developing into a normal, health embryo and then fetus. It was reported last year that embryonic stem cells were derived from mouse embryos using this technique. The ACT letter appears to be the first report that the technique can be successfully performed on human embryos. ACT's press release is here. More details are also available from the statement issued by ACT's ethics advisory board.
Despite the head-on challenge this technique represents to current ethical objections to harvesting embryonic stem cells, both papers report that the news was met with different degrees of skepticism, dismay, and downright hostility by the U.S. Conference of Catholic Bishops ("gravely unethical" -- the bishops also oppose IVF and PGD), Glenn McGee ("this will please no one" -- McGee is described as a long-time critic of ACT), and the immediate past chair of the President's Council on Bioethics, Leon Kass ("'I do not think that this is the sought-for, morally unproblematic and practically useful approach we need.' He said the long-term risk of P.G.D. testing is unknown, and that the present stem-cell technique is inefficient, requiring blastomeres from many embryos to generate each new cell line. It would be better to derive human stem cell lines from the body’s mature cells, he said, a method that researchers are still working on.")