Two respected scientific journals today reported that Chinese researchers have created baby mice out of induced pluripotent stem cells ("iPSCs"), an advance that raises difficult ethical questions and could reignite the culture-war battles over stem cell research that have subsided over the last two years.
Many conservatives oppose human embryonic stem cell (hESC) research, and President George W. Bush severely limited its funding, because the five-day old embryos (called blastocysts) that are used are living organisms and, if implanted into a uterus, could mature into people. Although President Obama lifted the Bush funding restrictions, the NIH released new guidelines that are still solicitous of the discomfort many Americans feel about using blastocysts for medical research: the Obama administration will fund such research only if the blastocysts used are "extras" created in in vitro fertilization clinics and would otherwise be destroyed anyway. Want to create a blastocyst in a test tube in order to produce stem cells? Don't look for federal funding, even from a Democratic administration.
The new federal regulations have provoked relatively little media attention, in part because most scientists have believed for the last year or two that hESCs are a transitional technology about to be overtaken by a newer one. In late 2007, scientists succeeded in reprogrammed ordinary adult skin cells (and other types of adult cells) into cells that seem to behave, for all practical purposes, like hESC cells. Scientists still aren't sure that these new iPSCs will behave exactly the same as hESCs for purposes of medical research, but the available evidence looks good, and iPSCs have a number of advantages over hESCs. They are much easier to produce than hESCs, and unlike hESCs, iPSCs offer the potential of allowing scientists to one day use a patient's own cells as the basis for creating a stem cell treatment that would not create problems of immune system rejection. And, of course, iPSCs do not come from embryos that could develop into a person, so iPSC research has met with widespread approval by conservatives who oppose hESC research.
But what now? If an iPSC can develop into a baby, just as a blastocyst can, why is it any less troubling to use iPSCs for medical research than it is to use hESCs? One possible response is that iPSCs can't become people without human intervention, but the same can be said of the blastocysts created in test tubes that are used for hESC research, which need to be placed in a womb. A difference between iPSCs and blastocysts is that the latter have a new, unique genome, whereas the former have the same genome as their donor. But we don't think identical twins are any less morally valuable because they lack a unique genome, and we wouldn't think that a cloned person was not a person, just because she had the same genome as her genetic donor.
My view is that today's development underscores the logical problem with treating blastocysts as if they have the same moral worth as a person. If it seems implausible that we should treat every skin cell as if it were a person, this is because the foundation of personhood is not a human genome plus potential. There must be something more, whether it be a neuronal structure, sentience, consciousness, the ability to imagine a future, etc. But for the unconvinced — and especially those whose religious or ideological commitments make them opposed to any research using blastocysts — opposition to iPSC research might be the only internally consistent position to take.