A major biological breakthrough - heralded by many as a key step in the quest for more effective treatment of disease - is likely to reignite a debate over use of human embryos for biomedical research.
The storm, which may reach Capitol Hill as soon as January, when the new Congress convenes, concerns lawmakers' refusal to use federal funds on any human-embryo research. It could set up the most serious clash yet between two groups that define themselves as protectors of human life - anti-abortionists and certain religious leaders on one side, and doctors and research biologists on the other.
The stir centers on the work of two science teams, which even bio-tech critic Jeremy Rifkin says is "a remarkable development."
Drawing material from surplus embryos and aborted fetuses, the teams have isolated and nurtured the basic cell type from which more-specialized cells in the human body emerge. Their achievement is the first step toward harnessing these cells, called embryonic stem cells, to treat a wide range of diseases. Other biologists hope it will also help unlock secrets these cells hold about the earliest stages of a human's physical growth.
"This is going to be a heated, much-debated subject," says Arthur Caplan, director of the Center for Bioethics at the University of Pennsylvania Health Systems, which embraces the medical school.
The breakthrough also raises anew questions about the appropriate oversight role of government in biological research. Until now, it was not certain that these stem cells could even be isolated and cultured - so there was no imperative for Congress to revisit the issue, says Dr. Caplan.
But now, as researchers and patients foresee benefits from embryonic-stem-cell-based treatments, "the pressure to change policies will mount," he says. "This is going to be one of the first things the new Congress will face."
One team's work, published in today's edition of the journal Science, drew its supply of stem cells from surplus embryos donated by patients at an in-vitro fertilization clinic run by the University of Wisconsin at Madison's medical school. The team was able to remove stem cells from five different blastocysts - hollow structures of about 140 cells that build over several days after fertilization. Each embryonic stem cell is capable of becoming almost any cell type contained in the human body - blood cells, muscle-tissue cells, or nerve cells, for example.
This specialization begins to occur just a few days after stem cells form, says team leader and University of Wisconsin developmental biologist James Thomson. Once the team extracted the stem cells from the blastocysts, it was able to put the cells' further development on "hold" and grow them indefinitely in cultures. In tests, the team watched as the cells continued to develop into more-specialized cells.
"By itself, this was a small technical feat," Dr. Thomson says modestly, adding that, with more basic research, these cells "can revolutionize many aspects of transplantation medicine. I expect we'll see the first treatments within my lifetime."
Johns Hopkins University physiologist John Gearhart calls the work "a major technical achievement with great importance for human biology."
Dr. Gearhart leads a team that has isolated and cultured human embryonic stem cells using "primordial germ cells" from aborted fetuses. Like Thomson's group, Gearhart and his colleagues were able to prevent the stem cells from specializing and were able to grow them in cultures.
THE final goal is to stimulate embryonic stems cells to develop into specific tissue cells for organ and other transplants. But in the near term, uses for the cells will likely center on genetic studies and drug screening, says Thomas Okarma at Geron, Inc., the Menlo Park, Calif., biotechnology firm that funded the two teams' research.
Through genetic engineering, stem cells also could be a tool for studying the role of genes mapped by a federal effort to determine the function of all the genes in a human body.
As a result, researchers such as Gearhart are calling on Congress to lift its funding ban. That would allow more researchers to tackle the human stem-cell problem, he says. Moreover, federal funding would let government set and enforce guidelines for embryo research, adds Caplan, who is concerned a continued ban would drive embryo research further into the secret and unregulated private sector.
But the debate over federal funding is likely to be contentious. Caplan expects vocal opposition from those who hold that human life begins, and remains sacred, from conception. "That's still controversial," he says, "but It is clearly unethical to make embryos exclusively for research purposes." It's preferable, he adds, to use "orphaned" embryos from fertility clinics - as long as donors consent to allow their embryos to be used for research. As many as 25,000 frozen embryos now exist in clinics across the US.