A battle over what limits to place on researchers seeking cures for disease will reach a new stage today as the National Institutes of Health accepts the first-ever applications from scientists who want money to experiment with cells from human embryos.
It is not clear how many scientists will apply for the federal grants. Many are deterred by the fact that President Bush may soon block the money on the grounds that the government should not fund research in which human embryos are destroyed. Bush has stated his personal opposition to embryo research, and his administration is reviewing the legality of federal funding.
But scientists call the work promising. And now, even as they fight Bush's possible opposition, some scientists are arguing that they must undertake something even more controversial in their attempts to cure disease: combine embryo research with human cloning.
With journal articles and early-stage experiments, some scientists are building a case that cloning might do something that embryo research cannot do alone: create cells and tissues that could be swapped into patients like new parts on an old car.
"There's no doubt that this kind of research is going to happen," said Lee Silver, a professor of biology and public policy at Princeton University. "It's a question of when and of how many people are going to die who could have been saved."
If cloning technology has, in fact, reached the point where it can be considered in medical treatment, even in a preliminary way, then it shows how science often moves far faster than lawmakers and the public can follow.
Britain in January became the first nation to legalize the creation of cloned human embryos for medical research. No federal law stops U.S. researchers from pursuing the same research with private money, but many scientists say the work will not move quickly without help from the federal government. And opposition from anti-abortion groups and others is so strong that the work is unlikely to win federal funding in the near future.
Scientists who support the research do not want to use cloning to create children but rather to create tissues that could be transplanted into patients. The process is often called "therapeutic cloning," to distinguish it from cloning aimed at reproduction.
Like the research that the NIH may soon fund, therapeutic cloning tries to take advantage of a remarkable type of cell within embryos called the stem cell.
Stem cells arise when an embryo is only a few days old. They have the ability to become anything in the body--brain, bone, nerve cells and the like--but they have not yet been "programmed" by the embryo to take on any of those specialized roles.
Scientists want to learn how to guide stem cells to become new heart tissue for cardiac patients, insulin-producing cells for diabetics, and brain cells for people with Parkinson's and Alzheimer's diseases. They say stem cells, first isolated only two years ago, provide the first real hope for patients with many incurable and life-threatening diseases.
The NIH announced in August that it would fund experiments using stem cells from human embryos, though it has barred cloning. Research proposals, which are due today for the current round of funding, must pass a special ethics review and then compete against applications in other areas of medicine.
"Talking to our members, I don't think there are going to be a lot of applications. People don't want to go through the whole process only to find out that all the funding is blocked," said Tim Leshan, director of public policy for the American Society for Cell Biology.
Even so, some scientists want to push the research in new directions through cloning, which would invite even more controversy.
They focus on the fact that the human body is far more temperamental than a car and it cannot always accept new parts. In fact, many organ transplant patients reject their new heart or kidney as foreign material, consigning the patients to a lifetime of anti-rejection drugs.
Therapeutic cloning might solve this problem. It envisions that DNA from a patient would be used to create an embryo. Then, stem cells from the embryo would be used to create the cells or tissue that the patient needs.
Because the new tissue would have the same genetic makeup as the patient, it might not be rejected by the patient's body.
Dr. Harold Varmus, a former director of the NIH, has said that therapeutic cloning and related work could unleash "some of the most promising new approaches to the treatment of human disease." Three researchers and three bioethicists, including Silver, wrote recently in a professional journal that therapeutic cloning could "transform medicine."
But anti-abortion groups and others oppose stem cell research, because human embryos must be destroyed to obtain the cells. And if taking cells from embryos is controversial, the idea of cloning people to create those embryos touches off an even stormier debate.
NIH rules permit only one source of embryo stem cells. They must come from embryos produced by couples at fertility clinics but which the couples no longer need in their attempts to have children.
In therapeutic cloning, by contrast, scientists would create embryos themselves to produce the stem cells. "I call it destructive cloning--cloning followed by the destruction of the product," said Richard Doerflinger of the National Conference of Catholic Bishops.
Moreover, Doerflinger said, the act of cloning itself is "reprehensible because it turns human reproduction into a manufacturing process. It really turns humans into mere objects. And we think it's particularly disdainful of human life to make a life solely to be experimented on."
Supporters of therapeutic cloning counter that an embryo, at only several days old, is not equivalent to a person. To support that point, they note that many embryos self-destruct in the womb rather than grow into children.
"Eggs are not chickens, and acorns are not oaks," Silver and his co-authors wrote in their article, which appeared in the Journal of the American Medical Assn. in December.
Several experiments have suggested that therapeutic cloning has promise, at least in animals.
Last year, an Australian team reported that it cloned mice to produce embryos, then used stem cells from those embryos to produce muscle and nerve cells.
In Massachusetts last year, Dr. Anthony Atala of Harvard Medical School and Children's Hospital in Boston cloned a cow to produce an embryo. Then he took tissues from the cloned embryo and sewed those back into the adult cow.
Atala and his colleagues wanted to see if the cow would reject the cloned cells, much as a patient might reject a new kidney or heart. Instead, the cells grew and thrived.
Atala said the experiment showed that cloning might overcome the problem of tissue rejection. "This is a proof of principle, but it's many, many steps away from a therapy," he cautioned.
The experiment, which is continuing, was done in cooperation with Advanced Cell Technology Inc., a Worcester, Mass., biotechnology company. Results have not been published.
Dr. Lorenz Studer of the Memorial Sloan-Kettering Cancer Center in New York City said he wants to produce the specialized brain cells that are destroyed in Parkinson's disease.
Working with mice, scientists have already produced these cells from embryo stem cells. Now Studer is trying to determine whether the same cells can be produced from the embryos of cloned mice.
Studer calls the work important, but he warns that there are many hurdles.
When researchers use cloning to produce live animals, they often create lots of embryos that fail to grow properly, or which result in deformed offspring. This suggests that cloning has left the embryo with a genetic defect, Studer said.
Scientists must be sure that similar defects do not appear in the tissues transplanted into patients, Studer said, so that the tissues "don't do things they're not supposed to do" in the patient's body.
Still, he said, using cloning to help patients "is a concept that wasn't thinkable several years ago, and at last it's conceptually possible."