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Nancy’s Stand
By Wil S. Hylton, September-October 2003
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So what is it about stem cells that got Mrs. Reagan so excited? Their nearly
boundless potential to heal.
In broad strokes, it works like this: Your whole body is made up of cells.
Think of them as building materials. You have many types of them, like bricks,
and lumber, and drywall. That is, the cells that make up your skin are different
from the cells that make up your bones, which are different from the cells in
your lungs, and so on. Now imagine that the cells in one part of your body are
damaged. Doesn't matter how they got that way. Doesn't matter if it's cancer
or a car accident. Let's just say they need to be replaced. Unfortunately, there's
no obvious place to get new cells. You can't just go to the hardware store and
stock up. What you have to do, instead, is make some new cells. That's where
your stem cells come in. Think of your stem cells as a source of raw materials—the
timber that becomes lumber or the clay that becomes a brick. They can be found
right next to your other cells, buried in your tissues, but they are not like
your other cells because they can replicate and make new cells. Scientists are
researching ways to extract a stem cell, put it into a culture, replicate it
several times until there's a larger mass of new cells, and then transplant
those new cells back into your body to replace the damaged ones. Because the
cells are duplicates of your own, they will be a perfect genetic match and will
transplant without risk of rejection.
Simple, right? A big catch: There's a limit to the number of cells you can
generate that way. You see, most adult stem cells can double only a few times
in culture. So if you don't need a lot of new cells, you're in good shape. You
just start with a few stem cells and get going. But if you need, say, a few
thousand new cells, or a million, or a billion (the number required for, say,
a major organ repair), well, you're out of luck. That's when you just might
need embryonic stem cells.
What differentiates an embryonic stem cell from an adult stem cell is pretty
straightforward: The embryonic stem cell is extracted from an embryo, usually
about five days old. This is done for two reasons: Number one, embryonic stem
cells can reproduce indefinitely, so you can make as many spare bricks or two-by-fours
as you want. You just put the embryonic cells into a culture and wait until
you have enough new cells. You've got an unlimited supply, so you never have
to worry about running out. Needless to say, scientists like the sound of that.
Just like everybody else in the universe, they'd rather have an unlimited resource
than a limited one. But the second reason embryonic stem cells are harvested
is even more compelling: An embryonic stem cell is capable of turning into any
other type of cell. So, whereas a stem cell taken from your skin could be used
to make new skin cells, you couldn't use those same stem cells to produce, say,
new brain cells. You'd have to get brain tissue to do that, but the adult brain
stem cells are too rare to make that practical. Or you could just make new brain
cells from an embryonic stem cell. Or new spinal cord cells. Or virtually any
other type of cells. They wouldn't be your own cells because you're not an embryo
anymore, so there'd be a higher chance of transplant rejection—but as with other
transplants, the benefits might outweigh the risks. Scientists don't yet know
how to instruct embryonic stem cells to turn into one cell type or another,
but they're getting closer.
The reason embryonic stem cells are so much more flexible than adult cells
is that they haven't yet become any particular cell type. In other words, they
are young and easy to manipulate, while adult stem cells are older and more
set in their ways. So you could, at least hypothetically, use an embryonic stem
cell to repair a damaged cornea, a spinal-cord injury like Christopher Reeve's,
or even a brain disease like Parkinson's or Huntington's or Ronald Reagan's
Alzheimer's. Anytime cells have been damaged or destroyed, embryonic stem cells
offer the hope of generating new, flawless replacements.
In the summer of 2002, this distinction between embryonic and adult stem cells
was so clear, and the advantage of using embryonic cells so obvious, that the
debate over stem cell research was rarely a matter of scientific disagreement.
For the most part, scientists from all political perspectives could agree that
embryonic stem cells were a vastly superior research tool. The debate was focused
instead on whether it was morally acceptable to use them. After all, although
it's possible to remove some types of adult stem cell without causing any significant
damage to the donor, embryos are so small and so vulnerable that taking a mere
30 stem cells from them is taking nearly half of their total mass. As such,
it's guaranteed to kill them. Needless to say, this raises the stakes of the
debate. Anybody who believes that an embryo is a human being isn't likely to
approve of killing one. On the other hand, people who support the research point
out that embryonic stem cells are taken from embryos left over from in vitro
fertilization, so they would have been killed anyway. As Pennsylvania Senator
Arlen Specter, a prominent Republican supporter of the research, puts it, a
discarded embryo is "not on its way to life."
It was in this climate of awkward ethical nuance that a rift of passions began
to develop in the Republican Party, beginning a few years ago and finding expression
in a Senate hearing during April of 2000, when Specter squared off against the
more conservative Senator Sam Brownback of Kansas.
"You are taking live human embryos," Brownback protested. "You
had the Nazis in World War II saying of these people, 'They are going to be
killed. Why do we not experiment on them and find out what happens with these
experiments? They are going to die anyway.' "
"But they were living people," Specter insisted.
"These are living embryos!" said Brownback.
Struggling to find some middle ground between the two camps, George W. Bush
quickly found himself in a personal and political gantlet. One thing was clear
to him: In his heart (as well as his core constituency), there was moral certainty
that killing embryos was wrong. On the other hand, he also knew that scientists
had already begun to culture cells from embryos. In the cases of those cell
colonies, or "cell lines," the damage was already done—the embryos
were no longer alive to defend. To Bush, that made the issue more difficult
to decide. Was it more important for him to approve the use of those cell lines,
so the public could benefit from them? Or should he, as President, set a moral
standard and prevent government scientists from using such methods? The decision
tore at Bush's conscience, perhaps more than any other issue in his presidency,
including war. In the end, he decided that the research was too promising to
bypass, and in August of 2001 he granted government-funded scientists the right
to work with all existing embryonic cell lines. But he stipulated that they
could not develop any new embryonic lines. (At the time, Bush believed there
were more than 60 cell lines available for government research—the number has
since been revised down to a dozen.)
If it seemed like a fair compromise to many folks, it felt like defeat to many
people in Nancy Reagan's camp. Most scientists in favor of embryonic research
insist that the existing cell lines aren't nearly adequate to explore the full
range of research possibilities. For that, scientists would need hundreds, maybe
thousands, of different stem cell lines. Among other things, a larger variety
of cell lines would give transplant recipients a better chance of finding a
donor with their genetic type.
But even as Mrs. Reagan launched a campaign to change the President's mind,
even as she visited the White House last summer, lodging in the Queen's Bedroom
and, according to The New York Times, lobbying Chief of Staff Andrew Card for
his help on the issue, a group of stem cell scientists in Minnesota was unwittingly
working against her. At the Stem Cell Institute at the University of Minnesota,
a team of researchers led by Catherine Verfaillie, M.D., announced a critical
discovery in June: Working with adult bone-marrow stem cells in mice, they were
able to achieve nearly the flexibility of embryonic stem cells. That is, the
bone-marrow stem cells divided more than a hundred times, and they could morph
into a tremendous variety of cell types, including muscle cells, liver cells,
bone cells, cartilage cells, and neurons, or brain cells. Suddenly, Mrs. Reagan's
campaign looked a little less necessary. While she remained convinced that all
stem cell research should go forward, the discovery was so promising, and made
the new bone-marrow cells appear so fruitful, that even some of Mrs. Reagan's
supporters were beginning to wonder: If adult stem cells are just as good, then
why use embryos at all?
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