9"This is a really significant thing that he has done," Hurlbut says of Jaenisch’s work. "It establishes the scientific feasibility of the idea." Hurlbut believes that CDX2 acts so early in development – at the eight-cell stage in mice – that the entities created by Meissner and Jaenisch should not be called embryos. But many ethicists disagree.
"It doesn’t solve the ethical problem," says Nigel Cameron, chairman of the Center for Bioethics and Culture. "If you create a deformed embryo, it’s still an embryo." Still, that doesn’t negate the entire concept of altered nuclear transfer, he says; scientists could look for different or additional genes to alter that might yield stem cells without creating embryos.
Rev. Tadeusz Pacholczyk, a Roman Catholic priest, PhD in neurobiology, and director of education for the National Catholic Bioethics Center, agrees. "I’m glad to see Jaenisch’s work," he says. "I’m not convinced this resolves anything, but I think it points in a hopeful direction to the way science might be used in the future."
The next step is to consider altering some combination of genes rather than a single gene, Pacholczyk says, "so it really doesn’t make an embryo." One proposal he finds promising is that of Markus Grompe, a stem cell researcher at Oregon Health Sciences University. Rather than turning off one or more genes to disable embryonic development, Grompe plans to force the donor cells to produce one or more transcription factors typically found only in embryonic stem cells. These proteins direct the activity of hundreds of genes that keep the cells from developing into specific cell types. The eggs might also be encouraged to make these proteins. Grompe would then follow typical nuclear transfer techniques, injecting the nucleus of the donor cell into a nucleus-stripped egg. The end result would be a pluripotent stem cell that had never passed through an embryonic stage.
Hurlbut also thinks Grompe’s ideas have potential. The CDX2 work, he says, is just a starting point. "This is the beginning of a constructive conversation," he says. "We’re going to get in there and have a cooperative dialog and see if we can arrive at an acceptable definition of embryo, organism, human. If we don’t do this, we’re going to have just one battle after another."
Evan Snyder, director of Burnham Institute’s Program in Stem Cells and Regeneration in La Jolla, CA, has worked with Hurlbut in the past and shares his hope for a compromise. "Our hypothesis is that in a pluralistic society, efforts to reach a consensus are worthwhile," he says. Even if the two new techniques fail to work in human cells or fail to satisfy critics, "no experiment is useless, and in trying to derive cells in alternate ways, we may learn some new things."
But other researchers and ethicists say there is probably no way to stop the moral merry-go-round to which both opponents and supporters of stem cell research find themselves strapped. Neither Lanza’s nor Jaenisch’s approach really solves the moral dilemma, says Sean Philpott, a research microbiologist with the New York State Department of Public Health and executive managing editor of the American Journal of Bioethics. "This is scientific hand-waving," he says. "We are putting so much time and effort into trying to come up with solutions that are acceptable to all sides, when really there are no acceptable solutions."
Ultimately, Philpott believes, "We’re going to have to accept that there are going to be a considerable number of Americans who are morally opposed to embryonic stem cell research. That doesn’t mean that we shouldn’t pursue it."