On Sunday, the Washington Post described how fuzzy language (and fuzzy logic) can tie knots in the best intentions of stem cell scientists. During his veto ceremony in June, Bush issued an executive order instructing the NIH to rewrite the rules for funding stem cell research. He said he thinks there are “ways to develop stem cell lines without the destruction of human life.”
What are these ways? (Use the calendar to your right to navigate to the 30 June post, Will Newfangled Methods Replace Embryonic Stem Cells?)
Here’s one of them. Below is a simplified figure of in vitro fertilization. After incubating an fertilized egg in the laboratory, the four-day-old embryo (called a blastocyst) is implanted into the uterus.
If there’s a suspicion of a genetic defect, the embryo can be tested by removing one cell from the 8-cell stage. If the test comes back positive, the embryo is discarded; if it comes back negative, it’s implanted. The test, used for fifteen years or more, is called Preimplantation Genetic Diagnosis (PGD) and it seems safe. Researchers at a biotechnology company, ACT, believe they have discovered a way around Bush’s moral blockade. At the same time an embryo is tested for PGD, why not let the lone cell divide and use one for the PGD test and the other to make a line of stem cells? (Alternatively, two cells might be sampled rather than just one.)
But the ACT approach is no solution for those who believe, as Mr. Bush does, that the embryo is a person and has interests and rights.
The Catholic Church says no to IVF generally. And for hardliners like the Rev. Tadeusz Pacholczyk, director of education for the National Catholic Bioethics Center, the technique represents the exploitative and manipulative use of a human being. Richard Doerflinger of the U.S. Conference of Catholic Bishops said last year, “It is widely believed that one cell of a very early embryo may separate and become a new embryo, an identical twin.” To his line of thinking, removing the cell is equivalent to killing a “potential person”, never mind a real one. (Whether every cell in an early embryo has this potential is the subject of intense debate among developmental biologists and embryologists.) Others say “no” to PGD because it can’t be proved beyond a shadow of a doubt that the technique might cause some unseen future harm.
But for the majority of us, a two- or four-day-old embryo is not a person, including the thousands of frozen embryos thrown away every month.
One might ask: If we didn’t spend time and brainpower designing end runs around a presidential policy, what other kinds of ingenious solutions to treat human disease could we uncover?
(graphics courtesy of Susie Prohaska and the Weissman laboratory)
