The field of stem cell research is changing shape almost as fast as the flexible cells themselves. A series of new techniques has moved the stem cell debate onto new technical, political, and ethical landscape, where it may be possible to find a clear path through the current stalemate.
Before the recent developments, it was more-or-less accurate to talk about two kinds of stem cells: adult and embryonic. Adult stem cells, isolated from a variety of tissues including newborns' umbilical cords, are uncontroversial. Not so embryonic stem cells, which until now have been derived from "surplus" embryos that were created but aren't needed for assisted reproduction.
This two-part typology no longer holds. Depending on how you count, there are now two or three additional stem cell varieties. Each differs from the others in some important details. And in those details lie some significant devils.
As is well known, many people are uneasy about research that involves destroying human embryos, and some - notably religious conservatives - adamantly oppose it. This is the devil that has dominated the stem cell debate, and that the new developments may dislodge.
Last November, research teams on two continents announced the creation, out of ordinary skin cells, of stem cells with all the powers of "standard" embryonic stem cells, and more. Since this reprogramming approach does not use embryos at all, logic suggests that it should end the stem cell stand-off. But discouragingly, scientists' fears that it would be used as an excuse to marginalize or de-fund embryo research triggered a new round of familiar acrimony.
A second development came in early January, when a Massachusetts-based biotech company reported making embryonic stem cells out of single cells plucked from very early-stage embryos, without harming them. It developed this "single-cell biopsy" method in part to satisfy religious objections to embryo-destructive research, but initial reactions from religious conservatives dispelled that hope.
It's still possible that either or both of these new techniques could wind up calming the stem cell wars. A third development - last month 's news that a small San Diego company called Stemagen had successfully produced cloned human embryos - moves in the opposite direction.
Stemagen's CEO described cloning-based stem cell research as the "holy grail" of biomedical science. Because cloned embryos could hypothetically be used to produce disease-specific stem cells, it initially excited many. But for a handful of scientists, it has become more of an ideological quest than a balanced scientific endeavor.
Cloning-based stem cell research was always speculative, and ten years of efforts to move it forward have proved it both technically difficult and ethically fraught. It has attracted an unusual share of outright fraud and of grandiose claims about imminent cures; the exaggeration that discredits so many claims about stem cell research in general has been even thicker in statements about research cloning. And now it now appears that cell reprogramming may make research cloning obsolete.
But the social and ethical complications remain. One serious issue is the very large numbers of women's eggs that cloning research requires. Obtaining these eggs involves giving women a series of powerful hormonal drugs to first "shut down" and then "hyper-stimulate" their ovaries. It's an invasive, risky procedure.
Cloning for research also invites unscrupulous headline-seekers to try their hand at cloning for reproduction - that is, at producing cloned human beings. And in the U.S., unlike dozens of other countries, we still have no federal law prohibiting this.
These problems are serious enough that only a few researchers around the world remain gung-ho for the cloning crusade. Cell reprogramming convinced the most famous cloning enthusiast, Ian Wilmut, to abandon it.
So what's the best path ahead on the new stem cell landscape? Disagreements about the status of embryos notwithstanding, the majority of Americans tell pollsters that they support embryonic stem cell research if it's conducted ethically and with responsible oversight. Here's a program that fits those values, one that could be taken up by any of the Democratic presidential candidates and some of the Republicans.
First, let's loosen the Bush administration's restrictions so that stem cell research using otherwise discarded embryos is eligible for federal funding and subject to federal oversight. Second, let's do what everyone knows is the right thing, and pass a law against cloning human beings. Third, let's put research cloning on the far back burner, in order both to protect the health of women and to make the best use of our scientific talent and resources.
Stem cell research provides an early warning of the ethical and social issues we'll confront as powerful new biotechnologies appear on the horizon. We'll need to choose among them wisely, use those we choose responsibly, and regulate them effectively. Chasing after unneeded and unethical "holy grails" won't help us meet those challenges.