Posted on Wed, Apr. 03, 2002
By Lisa M. Krieger
The translucent dot of cells floating in the petri dish of a cloning lab has not yet taken the shape of a person, but someday it could. Does it deserve protection?
That's the ethical question now being debated in Washington, D.C., where lawmakers are in the midst of a new struggle to regulate cloning.
The dot in the dish, a tiny human pre-embryo only a few dozen cells in size, may hold a cure for Alzheimer's, Parkinson's and other devastating diseases, making it the hottest ticket in biotech. But to extract these cells for disease research, the embryo must be destroyed. It is that dilemma that is stirring strong arguments among doctors, patients, scientists and religious leaders, creating one of this year's biggest scientific battles in Washington.
A vote on divisive "therapeutic cloning" -- or the creation of pre-embryos to be used in research -- is now widely expected once the Senate returns from recess next week. Competing bills could give the go-ahead to research involving the smallest embryos, or stop it in its tracks.
The fight is forcing politicians to answer a question that has eluded scholars for centuries: When, in the human developmental process, does life gain sanctity?
Two weeks, or 140 cells in size, respond supporters of therapeutic cloning, such as U.S. Sen. Dianne Feinstein, D-Calif. A landmark event in the development of a human being occurs at that age. Embryos younger than that should be eligible for use in research and therapy, they say.
But opponents of "therapeutic cloning," such as Sen. Sam Brownback, R-Kan., oppose all research involving pre-embryos, no matter how young. President Bush has said he supports this proposed ban.
"The challenge is to create new ways to think about what is sacred -- and what is needed for use in modern medicine," said R. Alta Charo, a professor of law and bioethics at the University of Wisconsin-Madison. "This will only be solved by a more nuanced discussion about what forms of human life are entitled to our protection."
Spiritual traditions offer little guidance, because opinions are divided among religious leaders of all faiths. And while debated for centuries, the starting point of life had little practical significance until recently. Until 20 years ago, reproduction remained largely in the hands of nature -- and pre-embryos existed only inside a woman's reproductive system. But now they can be grown in petri dishes, where they might be used to create lifesaving therapies.
The abstract debate suddenly turned real last fall with the startling news that the Massachusetts biotech company Advanced Cell Technology had created the world's first cloned human pre-embryos. Although all the embryos died within six days, it was a wake-up call to the promise, and peril, of the new technology.
In response to the breakthrough, Feinstein and Sen. Edward Kennedy, D-Mass., are sponsoring a "therapeutic cloning" bill that would allow pre-embryos to be created, harvested and then destroyed to offer hope to those suffering from devastating diseases. What is valuable are not the pre-embryos themselves but the so-called stem cells inside, which may hold the key to treating severe injuries and illnesses.
The embryo in this kind of research is just a cluster of cells, smaller than a period at the end of a sentence, they explain. It hasn't yet committed to becoming one individual -- it could split, leading to identical twins. Moreover, even under natural circumstances, its chances of survival are slim; biologists say two-thirds of embryos this tiny are discarded by the body before a woman knows she is pregnant.
At two weeks of age, something important happens: the so-called "primitive streak" appears. This is an advancing line of cells that determines the embryo's head-tail, left-right orientation. Additionally, some important genes are suddenly switched on. And individual cells begin to travel down different developmental pathways to becoming a liver, or a heart, or a hair follicle.
This maturation of the embryo is key not only in Feinstein's proposal but also in opinions of the California Advisory Committee on Human Cloning and most of the scientific community.
While conceding that their proposal means sacrificing embryos, they note that moral privilege is not an all-or-nothing matter. For instance, U.S. law does not accord a fetus the full legal status of a person until birth -- and third-trimester fetuses have different protections from first-trimester fetuses. "The primitive streak is an effective line to draw and say that is the beginning of a human being," said cloning expert Dr. Michael West of Advanced Cell Technology in congressional testimony. "We're talking about a little clump of cells that has no body cells of any kind . . . purely the raw material of cellular life."
These earliest pre-embryos are "microscopic dots -- little balls of cells that haven't formed a pregnancy yet," West said.
Dr. Ronald Green, ethics adviser to Advanced Cell Technology of Worcester, Mass., and a professor of religion and ethics at Dartmouth College, calls this stage "a blank sheet of paper." He also describes it as "the first spade in the ground, a ceremonial spade to start the construction of a building. It's the first step towards the production, the beginnings of a human life."
But Brownback and his supporters in the right-to-life community reject the portrayal of early embryos as dots, sheets of paper or digging implements. His legislation would outlaw "therapeutic cloning."
Just because young cloned embryos aren't yet someone, that doesn't mean they're no one, Brownback has said in numerous interviews. He believes that because life begins at conception, embryos should not be used in any research -- no matter how small they are or how much hope they may offer someone else.
Where to draw line?
The 140-cell, "primitive streak" dividing line is arbitrary and politically expedient, as easily moved as traffic cones on a freeway, opponents of therapeutic cloning say. It is no coincidence, they say, that the line is drawn after the time when pre-embryos can be harvested for their stem cells.
Just because a fertilized egg hasn't yet developed a "primitive streak" doesn't make it fair game for exploitation, Brownback said.
"If it is a living human embryo, it doesn't matter how it is created. It still has a right to life. Just because it is an embryo doesn't detract from the moral rights or innate dignity of that person," said the Rev. Joseph Howard of the American Life League's bioethics advisory commission.
Dr. Walt Larimore of Focus on the Family said "the stealing of stem cells from embryonic human life is human experimentation at its worst. . . . Any possible benefit of embryonic stem cell research would require the destruction of hundreds of thousands, if not millions, of tiny human lives."
As the debate heats up, identification of "personhood" in an embryo seems as elusive as ever. It is true that the life of a pre-embryo is a chain of many linked biological processes, not a bright line. But it is equally true that there are discrete landmarks in life -- and that in matters of morality and law, it is necessary to define them.
With a vote drawing near, some are urging a compromise rather than a permanent ban or blind and unlimited pursuit of research. A temporary moratorium, allowing time for further animal studies and public debate, might be a solution, they say.
"The fact is we really don't know what embryos are, and our obligations are indeterminate," said theologian David H. Smith of Indiana University. "We may need to be selective about the ways we move ahead. But our key virtues now are patience, a willingness to listen and courage. Fast and sweeping certainties are highly likely to be wrong."
"We are in a new territory," he said, "collectively feeling our way."
Copyright 2002, Mercury News