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Sunday, Nov 22, 2009
Well, that sounds great. Where's the controversy?
The ethical debate has to do with where we get the stem cells to use in therapy. Scientists have collected stem cells from umbilical cord blood, from fetal tissue, and from certain tissues -- like bone marrow -- in adults (and children). And in 1998, researchers developed a method to collect stem cells from human embryos -- these are called "embryonic stem cells." (An embryo, as we'll explain in more detail below, is the human body at its earliest stage of development; it is the product of the union of sperm and egg. You can see a neat visual chart of human development here.)
"Adult stem cells" -- that is, non-embryonic stem cells -- have proved beneficial in treatments for many diseases, mostly blood-related ailments such as leukemia. But many researchers believe that stem cells from embryos hold the most promise for eventually curing or treating some of our most pernicious diseases. That's because embryonic stem cells are considered more plastic -- that is, they can be turned into more kinds of body cells -- than those derived from, say, bone marrow in adults.
OK, so stem cells from embryos are considered more useful -- but they are also more controversial, right?
Right. That's because scientists derive stem cells from what's called the "inner cell mass" of the embryo, which is the part of the embryo that ultimately becomes the fetus. Therefore, when stem cells are removed from the embryo, the embryo is destroyed.
People who believe that "life" begins at conception, and that an embryo is morally indistinguishable from a human being, believe that it deserves the same protection as you or me. To these people, destroying an embryo to get stem cells that may treat or cure diseases that afflict fully developed human beings is not an acceptable trade-off.
Ah -- it seems we're in familiar territory here, the age-old question of when life begins, and at what point one can consider a clump of cells to have become a human being.
Yes, that's true. But you should note that the players aren't exactly the same as in the debate surrounding other "culture-of-life" fights, including abortion. As we'll explain in a minute, there are several biological and philosophical reasons to believe that an embryo is fundamentally different, and therefore deserving of a different ethical standard, from a fetus or a fully developed human being. Even many pro-life lawmakers recognize this difference, which is why so many Republicans defied their leaders to vote with Democrats on the Stem Cell Research Enhancement Act.
What's important in this debate, though, is that leading Republicans, including Senate Majority Leader Bill Frist, House Majority Leader Tom Delay, and President Bush, think of embryos as human beings. Bush calls embryos "real human lives," and he says they should not be destroyed. DeLay's rhetoric is even sharper. In a speech on the House floor opposing the latest bill, DeLay declared that harvesting stem cells from embryos constituted "the dismemberment of living, distinct human beings for the purposes of medical experimentation." He added: "The best that can be said about embryonic stem cell research is that it is scientific exploration into the potential benefits of killing human beings."
OK, I can understand that kind of language from Tom DeLay. But I seem to remember Bush being more open to compromise on stem cells. Am I wrong?
You're right that there is a perception that Bush has taken a reasonable middle-ground position on stem cells. It is a perception that the White House has sought to cultivate. On Aug. 9, 2001, after what he described as a period of intense inquiry and soul-searching during his first summer in office, Bush announced his stem cell policy in a televised speech to the nation. Federal money, he said then, would only be used to fund research on stem cells that had been collected from embryos prior to the date of his speech. His justification was that for those cells, derived from embryos that had already been destroyed, "the life and death decision has already been made." But research on stem cells derived from embryos destroyed after Aug. 9, 2001, would not be eligible for federal funding, Bush said.
This limitation, he insisted, would not greatly harm stem cell science. Bush explained that more than 60 stem cell lines had been created by that date -- enough stem cells, he believed, to allow scientists to "explore the promise and potential of stem cell research."
Something tells me he wasn't right about that.
He wasn't. Despite Bush's assurances, his policy has harmed the science. First, what Bush said about the number of stem cell lines that his policy would allow scientists receiving federal grants to work on was false. Instead of more than 60, there were only 22 stem cell lines created before Aug. 9, 2001, now available to scientists. These lines -- what some researchers call the "presidential lines" -- have proved useful to scientists, but largely "for basic research," Evan Snyder, a stem cell scientist at the Burnham Institute in La Jolla, Calif., told Salon last year.
Because the federally funded cells were prepared in the early days of stem cell research, many scientists are starting to "outgrow" them now, Snyder said. Indeed, it's unlikely that the cells currently approved for funding can be used in any actual treatment for human beings. Because pre-Aug. 9 stem cells were harvested mostly for research purposes and not for clinical medicine, they were kept alive using "feeder cells" from mice; scientists worry, therefore, that the presidential stem cells carry mouse viruses that would make them dangerous for human treatments.
Stem cells that were harvested after 2001 -- and which scientists can study using non-federal and private funding -- don't suffer the same problems. Newer stem cells can be prepared "without touching animal materials," Snyder said. "We've developed lines that are not killed by antibiotics. We can even grow cells that don't touch any biologics at all." But under Bush's policy, no research on these advanced stem cells can be funded with government money.
And this is the maddening thing about the Bush policy, opponents say. The president frequently touts the fact that his administration has given more than $50 million to fund embryonic stem cell research in the last four years. What he doesn't say, though, is that under his plan, the government's money has only gone for work on stem cells that scientists already know cannot be used in treatments to help human beings.
