A Promising Line of Cloning-Related Research.

Embryonic Stem Cells: A Promising Line of Cloning-Related Research

In December 1998, Gregg Easterbrook writes in the following article, two independent researchers announced that they each had isolated and copied a special type of cell (called a stem cell) from human embryos and grown the cells in the laboratory. Stem cells, Easterbrook explains, have the potential to develop into any kind of tissue in the body. Therefore, he relates, stemcell duplication might be used to provide sources for replacement tissues or organs, freeing doctors and patients from dependence on a limited supply of donated organs and the need to overcome the immune system's tendency to reject organ transplants. Easterbrook points out that, promising as it is, stem-cell research raises serious ethical questions about the use of human embryos and fetuses in scientific experiments. It also may make human cloning both possible and "respectable," a thought that many view with alarm, he notes. Easterbrook concludes by considering some of the implications of cloning humans. In addition to writing frequently for The New Republic, Easterbrook is the author of several books, including A Moment on the Earth: The Coming Age of Environmental Optimism.

For John Gearhart, a biologist at Johns Hopkins University, professional life had been an exercise in slamming against walls. Gearhart's specialty is Down's syndrome, triggered when one of the infant body's chromosomes copies itself once too often. Gearhart had spent 20 years trying to puzzle out this genetic error. "All our data suggested that Down's was caused by something that happens quite early in embryogenesis," he says—but the only way to find out what happens then would be to conduct experiments on human embryos, a prospect repugnant at best. Trying to think his way out of the problem, Gearhart wondered: What if there was a way to isolate and culture embryonic "stem cells," the precursors of all body parts? If they could be transferred to the laboratory, it might become possible to study the cytology of [cell changes following] conception.

Embryonic Stem Cells A Medical Boon?

Stem cells are the philosopher's stones of biology, magical objects capable of metamorphosing into any component of the body: heart, nerves, blood, bone, muscle. Mammal embryos begin as a clump of stem cells that gradually subdivides into the specific functional parts of the organism. Researchers have long assumed that, because stem cells are genetically programmed to change into other things, it would never be possible to control them, let alone culture them. But Gearhart and another researcher working independently, James Thomson of the University of Wisconsin, found this is not so.

In December 1998, Gearhart and Thomson announced that they had each isolated embryonic stem cells and induced them to begin copying themselves without turning into anything else. In so doing, they apparently discovered a way to make stem cells by the billions, creating a biological feedstock that might, in turn, be employed to produce brand-new, healthy human tissue. That is, they discovered how to fabricate the stuff of which humanity is made.

Researchers had already demonstrated that stem cells might be a medical boon by showing that such tissues extracted from aborted fetuses could reverse symptoms of Parkinson's disease. But so many fetuses were required to treat just one patient that the technique could never be practical, to say nothing of its harrowing character. By contrast, Gearhart and Thomson have found that stem cells can be reproduced roughly in the way that pharmaceutical manufacturers make drugs.

If researchers can convert stem cells into regular cells like blood or heart muscle and then put them back into the body, then physicians might cure Parkinson's, diabetes, leukemia, heart congestion, and many other maladies, replacing failing cells with brand-new tissue. Costly, afflictive procedures such as bone-marrow transplants might become easier and cheaper with the arrival of stem-cell-based "universal donor" tissue that does not provoke the immune-rejection response. The need for donor organs for heart or liver transplants might fade, as new body parts are cultured artificially. Ultimately, mastery of the stem cell might lead to practical, affordable ways to eliminate many genetic diseases through DNA engineering, while extending the human life span. Our near descendants might live in a world in which such killers as cystic fibrosis and sickle-cell anemia are one-in-a-million conditions, while additional decades of life are the norm.

Granted, sensational promises made for new medical technologies don't always come to pass, and some researchers are skeptical about whether stem-cell technology will pan out. But Harold Varmus, head of the National Institutes of Health (NIH), recently declared, "This research has the potential to revolutionize the practice of medicine." Notes John Fletcher, a bioethicist at the University of Virginia, "Soon every parent whose child has diabetes or any cell-failure disease is going to be riveted to this research, because it's the answer." Ron McKay, a stem-cell researcher at the National Institute of Neurological Disorders and Stroke, says, "We are now at the center of biology itself." Simply put, the control of human stem cells may open the door to the greatest medical discovery since antibiotics.

Disquieting Aspects of Stem Cell Research.

But there are disquieting aspects to stem-cell research, too. The first is that, for now, the only way to start the process of controlled stem-cell duplication is to extract samples from early stage human blastocysts. Gearhart used fetuses aborted by Baltimore women; Thomson, embryos no longer wanted by Wisconsin in vitro fertilization (IVF) clinics. Gearhart, Thomson, and other stem-cell researchers propose to continue drawing on such "resources," as some bloodless medical documents refer to the fetus and the embryo. This is possible because, even though Congress has placed a moratorium on federal funding for experimentation on most IVF embryos and most kinds of fetal tissue, no law governs what scientists can do to incipient life using private funding, either in research settings or within the burgeoning IVF industry.

Because the rules have banned embryo research by federally funded biologists, but not comparable private science, Congress has created the preposterous situation in which most stem-cell research is not being done by publicly funded scientists who must pass multiple levels of peer review and disclose practically everything about their work. Instead, most stem-cell science is in the hands of corporate-backed researchers. Gearhart's and Thomson's projects, for example, are being underwritten by Geron, a company whose name derives from "gerontology," and which anticipates a licensing El Dorado if stem-cell-based good health can be patented and sold to the seniors' market. "That a sensitive category of research is legal for people who are not publicly accountable, but illegal for those who are accountable, is just very strange," says Thomson.

Stem cells stand in the vanguard of human life. When a sperm penetrates an egg, it triggers a majestic sequence whose first step is to create a new structure that is composed mainly of stem cells. Biologists call such cells "undifferentiated," meaning they have not yet decided what they will be. Once the fertilized ovum [egg] implants in the uterus, differentiation starts. Some stem cells become placenta; others begin differentiating into the baby's organs, tissue, or blood. A stem cell might divide into any of the many components of the body, but, once it does, it can only continue growing as that part.

Because once a stem cell begins to differentiate it cannot turn back, biologists assumed that all stem cells could never turn back. But, in 1981, experimenters succeeded in extracting stem cells from the embryos of mice. By the mid-'90s, researchers had learned which chemicals instruct mouse stem cells to become particular tissue types and how to insert the new tissues back into mice. Loren Field of Indiana University became so adept at signaling mouse stem cells to become mouse heart cells that "his lab is almost pulsating with heart cells beating in dishes," Gearhart says....

Regulating Embryo Research

Both Gearhart and Thomson call on Congress to enact clear legal guidelines for their field. Thomson says, "The human embryo is the most special cell in biology, and there are just some things you shouldn't do to embryos"—mainly clone them. The primary point stem-cell researchers make in their own favor is that the cells they experiment upon, once brought into the lab, might be made into muscle or blood, but can no longer become a human being. This assertion seems true, though slightly cute, since the reason the cells cease being capable of personhood is that they've been artificially snatched from it. But then no one plans to conceive the IVF embryos that Thomson gets, and the fetuses Gearhart receives have already had their lives terminated. Neither biologist can change these things, though both might change others' lives for the better.

Reflecting the delicacy of the situation, stem-cell researchers are beginning to wrestle over the terms totipotent and pluripotent. A totipotent cell is what exists at the earliest germination stage, when each stem cell is capable of becoming a whole person. A pluripotent tissue is an isolated stem cell, capable of transforming into any desired cell type, but not of becoming a whole person. Not, at least, with current technology.

In January 1999, government lawyers sided with the pluripotent versus totipotent distinction, ruling that the NIH can begin funding stem-cell research on the grounds that the cells being worked with cannot become persons and thus are not embryos. This ruling hasn't yet taken effect; assuming it does, there will be beneficial results. Publicly funded scientists from research-center universities will jump into stem-cell investigations: research-center scientists are generally the country's best, and always the most accountable. Equally important, federal funding will move stem-cell findings into the public domain rather than allowing them to become proprietary. Geron shares samples of its stem cells with academics but asks the recipients to sign a statement that Geron owns the knowledge embodied in the cell line. Once public funding flows, proprietary claims will diminish.

Bringing public funding to stem-cell research will force a public debate on this new biology. There has been little so far. In Congress, a few members, such as Representative Jay Dickey of Arkansas, have declared themselves opposed, for pro-life reasons, to any research on embryonic cells. A few members, such as Senator Tom Harkin of Iowa, have openly endorsed stem-cell studies. Senator Arlen Specter of Pennsylvania was expected in 1999 to introduce legislation making human stem-cell research explicitly legal, as it is in the United Kingdom. But Specter says he will postpone action, feeling the time isn't right....

Outracing Understanding Today's situation with stem cells and cloning might be likened to what would happen if a fleet of modern jet fighters were teleported back in time to ancient Sumeria. First, the ancients would marvel at the objects, noting their extraordinary complexity—as scientists marveled when they first glimpsed the extent of the double helix. Initially, they'd be too scared to touch, and some would argue that the gods would punish those who touched. Eventually, the fear would wane, and, by poking and prodding and pushing buttons, someone would manage to start one of the plane's engines, generating thunder and fire. At that point, the ancients would believe they had "discovered" the true purpose of the mysterious objects, and that, now being able to manipulate the planes, they had become masters of them.

Owing to the stem-cell breakthrough, there now stands the prospect that our children will not only live healthier lives but that their children will be the final generation of Homo sapiens, supplanted by Homo geneticus or whatever comes next. Homo erectus didn't last, so there's no reason to assume Homo sapiens won't ever give way to a next stage. If all goes well, the advent of control over our own cells might offer our grandchildren many things we would wish for them.

But it's all happening much, much faster than society understands. It's also happening under conditions in which we are telling ourselves that we understand genes because we have learned to make them do certain things, but we probably know little more about the totality of our DNA than would the ancient who doesn't even realize that airplanes are supposed to fly. It's time to move biotechnology to the center of the national debate, so that we can sort out its rights and wrongs before sheer technological momentum imposes an outcome upon us.