Health

STEM CELLS A MORAL DILEMMA

Politicians and scientists ponder the ethics of using embryos in a promising research field

MARK NICHOLS August 27 2001
Health

STEM CELLS A MORAL DILEMMA

Politicians and scientists ponder the ethics of using embryos in a promising research field

MARK NICHOLS August 27 2001

STEM CELLS A MORAL DILEMMA

Health

Politicians and scientists ponder the ethics of using embryos in a promising research field

MARK NICHOLS

Like many medical researchers these days, Freda Miller is mesmerized by the healing potential of stem cells—versatile particles of life that can morph into the 200 or so types of cells needed to make a human being. Embryos are an obvious—but fiercely controversial—source of such cells. Now, scientists have begun to discover that stem cells exist in adult tissue as well, though they have proven to be elusive and difficult to handle. A molecular biologist at the Montreal Neurological Institute, Miller two summers ago hit on the idea of searching for adult stem cells in an easily accessible place. Recalls Miller: “I thought, ‘Wouldn’t it be just amazing if

An enormous potential for good

Stem-cell research holds out hope for new ways of treating a variety of diseases and | conditions. Among them:

Spinal cord Diabetes Muscular dystrophy Parkinson’s Alzheimer’s Eye damage

we could find them in skin?’ ” Working with mice, her team zeroed in on the dermis, the skin’s second layer, where scientists had found evidence that sensory receptor cells regenerate after injury.

Sure enough, they discovered mouse skin does contain stem cells, with the potential to become not only neural cells, but muscle and fat cells as well. Moreover, says Miller, whose findings were published last week in the journal Nature Cell Biology, preliminary evidence suggests the same cells exist in human skin. “When we found neural stem cells,” says Miller, “that was great. But when we found the other cells it was like a whole new world.”

Ever since scientist James Thomson of the University of Wisconsin succeeded in isolating living stem cells from embryos in 1998, researchers have seen a potential for medical miracles. Because stem cells can transform themselves into muscle, neural and brain cells, they could help to treat, or even cure, conditions ranging from diabetes and muscular dystrophy to Parkinson’s disease and stroke. But the fact that embryos are currently the most readily available source of stem cells has turned research in the field into a moral minefield, triggering furious debate in the United States between medical researchers and patient advocates on the one hand, and Christian fundamentalists and pro-life advocates on the other.

Attempting to satisfy both sides, President George W Bush oudined a policy on Aug. 9 that will permit U.S. government funding for research but only if it uses ex-

isting cultures of stem cells from embryos created by in vitro fertilization. The policy denies money to projects that would use embryonic tissue not already collected. The decision angered some American scientists. “It’s like making science with one hand tied behind your back,” says Lee Silver, a molecular biologist at Princeton University.

In Ottawa, a Parliamentary committee is considering legislation that would be less restrictive than the U.S. rules, allowing researchers to use tissue from early-stage embryos created by in vitro fertilization that otherwise would be discarded. So far, the issue has not sparked the kind of public debate that has raged in the United States. But it could flare up if the federal government in fact permits experiments on fetal tissue. “An embryo is not just a clump of cells,” says Dr. John Shea, a retired radiologist and medical adviser for Campaign Life Coalition Canada, a Toronto-based anti-abortion organization. “It’s a human individual, entided to life and dignity.”

Debate could also intensify if the healing promise of stem cells is borne out. “If effective stem-cell therapies based on embryonic tissue are developed,” says Ron Worton, scientific director of the Ottawa Health Research Institute and head of The Stem Cell Network, “we would need vast amounts of tissue. We’d be treating embryos as a commodity—and the debate would become much bigger than it is now.”

Which is why Miller’s discovery could be critically important, pointing as it does to the possibility that adult stem cells could eventually prove nearly as versatile as the embryonic ones. Scientists have also turned up stem cells in other parts of adult bodies, including bone marrow, the brain and in some muscle tissue. Last year, aToronto research team discovered retinal stem cells in animals and humans, raising the hope of new treatments in the future for diseased or damaged eyes. Until re-

cently, scientists believed that, unlike embryonic stem cells, adult cells could produce only a few types of tissue. Now, findings like Miller’s suggest that adult stem cells may have the potential for producing a much wider range of new tissues.

But adult stem cells have limitations— scientists find it firustratingly hard to make them multiply, unlike embryonic cells, which can proliferate indefinitely. For now, says Janet Rossant, a molecular biologist at Toronto’s Mount Sinai Hospital, “it’s too early to say which will be the best route to go—so it’s important that we move forward on both fronts, working with both adult and embryonic stem cells.”

Ottawa’s proposed rules would make that possible. The regulations are part of draft legislation that lays down guidelines for a variety of reproductive technologies, including in vitro fertilization and donor insemination, while banning the cloning of humans and the buying and selling of human embryos. The draft, under review

by the House of Commons standing committee on health, could be completed next spring. The committee has heard testimony on the stem cell issue from government officials, ethicists and representatives of religious groups, and plans to hear from medical researchers when Parliament resumes next month. So far, says committee chairman Bonnie Brown, an Oakville, Ont., Liberal, the hearings have “really been an intellectual exercise—an effort to understand. There are bound to be committee members who won’t like the proposals, but I simply can’t say at this stage what individual members think.”

If Ottawa’s proposed rules become law, will American stem-cell researchers head north to escape Bush’s restrictions? Already, one prominent U.S. researcher has announced plans to move to Britain, where liberal rules go so far as to permit scientists to create embryos solely for research purposes—a practice forbidden under the proposed Canadian regulations. But Ottawa’s Worton doubts relatively lenient rules would lure many American researchers to Canada, mainly because of the shortage of research money. “American scientists are so well funded,” he says, “there would have to be very compelling reasons for them to come here.” Experts estimate that funding for stem-cell research in Canada stands at about $10 million a year—a fraction of the more than $400 million spent last year in the United States.

The dearth of funding has not stopped Canadian scientists from scoring major breakthroughs. In 1992, Samuel Weiss, a University of Calgary neurobiologist, became the first to find stem cells in the brain. They routinely churn out new specialized cells for several parts of the brain, says Weiss, but not others. Working with mouse brains, Weiss now is trying to find ways to intervene in the process so that a damaged brain can repair itself. Can it be done? Sometime in the next decade, says Weiss, “we will come up with therapies to dramatically improve recovery from stroke or disease in the brain.” Of course, it’s possible researchers using embryonic stem cells could reach that goal first, as medical science explores the brave new world of stem cells.

Should Canada allow research using cells from human embryos?