Scientists create mixed-gender human embryos

Scientists in Chicago have for the first time made human embryos that are part male and part female, raising novel ethics questions and prompting calls for more oversight of the rapidly evolving field of human-embryo manipulation.

The experiments — described at a meeting in Madrid, Spain, of the European Society of Human Reproduction and Embryology — aimed to answer basic questions about human-embryo development and develop therapies for congenital diseases.

The hybrid embryos were destroyed after six days, when they had grown to a few hundred cells organized into a mixed-gender ball, according to a written synopsis of the work submitted by the research leader, Norbert Gleicher, of the Foundation for Reproductive Medicine.

Such work is legal in the United States if federal funds aren't used and if the male and female embryos that Gleicher merged were freely donated for research, as Gleicher reported they were.

Nonetheless, his presentation yesterday drew criticism from fellow scientists at the meeting, according to reports from Madrid. The experiments also angered U.S. opponents of human-embryo research and prompted some ethicists to refresh their long-standing call for a national debate about human-embryo studies — and perhaps creation of a national ethics board to review proposed experiments.

"I don't know if this work is 'right' or 'wrong,' but it should be reviewed and discussed long and hard before it's done," said George Annas, a professor of health law and bioethics at Boston University. "It's one thing if the right-to-life community has problems with your work. But if scientists hear you talk about your work for the first time and say it's outrageous, that says something."

Gleicher said he envisions one day using the technique to create babies for couples who were certain to pass on single-gene disorders.

He didn't specify any diseases, but one that could be affected is severe combined immunodeficiency (SCID), better known as "bubble-boy disease."

The idea is that if cells from a healthy embryo are put into a sick embryo, some of the cells in the resulting child will be normal and may correct the problem.

An abstract of Gleicher's work published in the program of the meeting says the experiment sought to find out whether human embryos with genetic defects might develop normally if, during the first few days of their existence, they were "seeded" with healthy cells that could take over the work of the defective cells.

To see if cells can survive transplantation from one embryo to another — and if transplanted cells can multiply normally in embryos — Gleicher transplanted one, two or three embryo cells from male embryos into 21-day-old female embryos.

He used different sexes because male cells are easy to track in a female embryo by virtue of the males' Y chromosome.

In 12 cases, the hybrid embryos developed normally, with male and female cells intermixed. In nine cases, the embryos developed abnormally. The team concluded that transplants of normal embryo cells represent a "possible treatment option" for embryos harboring genetic defects.

"I am by no means saying this is clinically ready for application. The principal purpose was to see whether transplantation of cells at this stage would work, and we have convincing evidence that the answer is yes," Gleicher said.

Experts rejected the idea that such treatment would become a reality.

"It is ethically objectionable," said Dr. Françoise Shenfield, coordinator of the European fertility society's ethics-and-law group.

Shenfield also said the treatment posed the risk of long-term health dangers for the future children involved.

"I cannot conceive of any situation in which this particular technique would be acceptable, and if it cannot be applied there is not much use in experimenting with it," Shenfield said.

Dr. Arne Sunde, chairman of the European Society for Human Reproduction and Embryology, said the technique could theoretically solve a genetic disorder in cases where only a few normally functioning cells are needed.

"In cases of a metabolic disease where a certain enzyme that makes body chemistry run is missing, you don't need to correct all the cells to avoid the symptoms," he said.

Besides possible physical complications, any resulting child would essentially have four parents, Sunde said.

Jeffrey Kahn, director of the University of Minnesota's Center for Bioethics, said the controversy is just the most recent manifestation of a problem that dates back 20 years, when the federal government decided it would neither fund nor oversee experimentation on human embryos. That has pushed the work into the private sector, he said, where oversight is all but nonexistent.

"It all comes back to what you think the moral status of the embryo is," Kahn said, adding that the situation is going to become more complicated as embryos are altered to the point of perhaps not being embryos. "The question is, 'What is it?' " Kahn said of Gleicher's creation. "If you think it is something with the moral status that you or I have, then you have a big problem."

Douglas Johnson, legislative director of National Right to Life, said in an e-mail that Gleicher's work was clearly unethical.

"Each member of the species Homo sapiens is genetically male or female from conception," Johnson wrote. "These are truly female human embryos who are being used as subjects for lethal and unethical experimentation."

Annas said he favored creation of a national review board that could consider the scientific and ethical value of such studies.

Local hospital- or university-based boards that review the ethics of proposed studies "are totally ill-equipped to consider these kinds of proposals," he said.

The President's Council on Bioethics, headed by Chicago physician and philosopher Leon Kass, has recently turned its attention to the question of whether reproductive medicine ought to be more thoroughly regulated.

Material from The Associated Press is included in this report.