THE STEM CELL CONTROVERSY

[This is well worth reading.]

New York Times
October 16, 2005

Scientists Devise Stem Cell Methods to Ease Concern
By NICHOLAS WADE

In a development that may shift the political debate over embryonic stem cells, researchers have devised two new techniques designed to alleviate ethical concerns. In one, the cells are derived without the need to destroy an embryo, the principal objection of abortion opponents who have strenuously opposed federal financing of the research. The other technique makes skin cells revert to the embryonic state in a way that prevents the embryo from implanting in the uterus. Both are described in today's online edition of Nature.

The technique for making embryonic stem cells without compromising the embryo was developed in mice and has yet to be adapted to humans, but the two species are very similar at this level of embryonic development. "I can't think of a reason why the technique would not theoretically work" in people, said Brigid M. Hogan, an embryologist at Duke University. If it does work in people, the technique could divide the pro-life movement into those who accept or reject in vitro fertilization, because the objection to deriving human embryonic stem cells would come to rest on creating the embryos in the first place, not on their destruction. "This gets around all of the ethical arguments except for that small minority of the pro-life community that doesn't even support in vitro fertilization," said Representative Roscoe G. Bartlett, Republican of Maryland, whose Web site describes him as "a pro-life legislator."

Until now, the only way of deriving human embryonic stem cells has been to break open the embryo before it implants in the uterus, a stage at which it is called a blastocyst, and take out the inner cell mass, whose cells will form all the tissues of the future infant. Although the blastocysts used in the procedure are ones that fertility clinics have rejected for implantation, opponents of abortion say destruction of any embryo is wrong. Congress has forbidden the use of federal funds for any such research, and federally supported scientists can work with only a small number of existing lines of embryonic stem cells that have been exempted from this stricture by President Bush.

Robert Lanza and colleagues at Advanced Cell Technology, a biotechnology company in Worcester, Mass., have now developed an alternative way of generating embryonic stem cells that leaves the embryo viable. At the eight-cell stage, reached by a fertilized mouse egg after its third division and just before the blastocyst is formed, they removed one cell. They then coaxed that cell, known as a blastomere, into growing in glassware and forming cells that have all the same essential properties as embryonic stem cells derived from the inner cell mass, Dr. Lanza's team reported. The seven-cell embryo was implanted in the mouse uterus and grew successfully to term. That part of the procedure is known to work with humans too, because it is the basis of a well-established test known as pre-implantation genetic diagnosis. In the test, one cell is removed from each of a set of embryos and tested for any of 150 genetic defects, giving the parents the choice of implanting an embryo that is disease free.

Dr. Lanza's technique is likely to be welcomed by many in the middle of the debate, although it has not won over the United States Conference of Catholic Bishops. Richard M. Doerflinger, its deputy director for pro-life activities, dismissed the technique, saying that pre-implantation genetic diagnosis itself is unethical. The technique "is done chiefly to select out genetically imperfect embryos for discarding, and poses unknown risks of future harm even to the child allowed to be born," he said in an e-mail message. Only a procedure that generated embryonic stem cells without creating or destroying embryos "would address the Catholic Church's most fundamental moral objection to embryonic stem cell research as now pursued," Mr. Doerflinger said in testimony last December to the President's Council on Bioethics.

. . . Markus Grompe, a leading stem cell scientist and a Roman Catholic who supports the church's teaching on the unacceptability of destroying embryos, praised the Lanza approach, provided that the extracted blastomere could not develop into an embryo all by itself. "I find it clearly less objectionable than the outright destruction of the embryo," said Dr. Grompe, who studies liver stem cells at the Oregon Health and Science University. In response to Dr. Grompe's reservation, Dr. Lanza said that individual human blastomeres had never been shown to create viable embryos. The reason is that by the eight-cell stage, each blastomere is probably committed to becoming either the outer shell of the blastocyst, which later forms the placenta, or the inner cell mass, which forms the fetus. Only the fertilized egg and the two-cell and perhaps four-cell stages retain the ability to form all the placental and embryonic tissues, Dr. Lanza said.

[There's more.  To read the whole article, click here.]
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