The study, published online Wednesday in the journal Nature, purports to have used single cells of 2- to 3-day-old human embryos (consisting of 8 to 10 cells) to produce stem-cell lines, a process that would leave the embryos themselves intact and able to survive in most cases, the research team says. The findings represent the latest advance in one of several ongoing projects seeking ways of generating stem cells without destroying embryos—an aim of some scientists due to U.S. law prohibiting federal funding of research that results in embryo destruction.
The project’s lead author, Dr. Robert Lanza, is hailing the finding as a large step toward an avenue of research he says most “rational” people would find ethically sound. “Up until now embryonic stem-cell research has been synonymous with embryo destruction, and I think this changes that paradigm,” Lanza tells NEWSWEEK.
But others in the field, as well as conservative religious groups, say that the technique, though innovative, might raise “more ethical questions than it answers.” Richard Doerflinger, deputy director of pro-life activities at the United States Conference of Catholic Bishops, says Lanza’s methods are unacceptable for several reasons, including the fact that the experiments leading to his recent advance—although done to develop a technique that would preserve embryos—actually destroyed embryos in the process.
“It does not solve the ethical dilemma,” Doerflinger says. “It’d be irresponsible to claim now that this is totally safe.”
Lanza’s method, employed on mouse cells last year by his company, is derivative of a diagnostic technique used in in vitro fertilization known as preimplantation genetic diagnosis (PGD). In order to test embryos thought to be at risk for serious genetic defects, PGD removes a single cell, or blastomere, from a couple’s embryo and examines it in a lab for irregularities. If determined to be healthy, the embryo can then, in many cases, be implanted into a woman’s uterus and is able to regenerate the lost cell and continue developing. In practice, Lanza’s technique would take a blastomere from an embryo donated for PGD, allow it to divide, and use the new cells to create stem-cell lines while sending one of the cells off for genetic diagnosis.
In his paper, Lanza says that of 91 blastomeres used, 53 divided. Of those, 19 stem-cell outgrowths were formed (stem cells that eventually developed into specified cells and were therefore unusable for stem-cell research) and two full stem-cell lines were formed (the material desired for further research).“Hopefully this will remove the last rational reason for anyone to oppose stem-cell research,” Lanza says.
But other researchers disagree, saying that the removal of the blastomere poses unknown risks to the embryo and in turn, to the life of the child, should the embryo be implanted and continue developing to birth. “The embryo is constituted so that it heals itself, but all healing has an effect,” says William Hurlbut, a Stanford University professor and member of the President’s Council on Bioethics who has proposed alternative methods for generating stem cells without destroying embryos. “It might be serious effects, it might be minor changes it might be nothing. We just don’t know.”
Still others, like Dr. Ronald Green, director of Dartmouth College’s Ethics Institute and chairman of Advanced Cell Technology’s Ethics Advisory Board, argue that the potential harm to the embryo is no greater than it would have been during a normal PGD procedure, which couples would have consented to. Lanza himself admits to possible risks to the embryo and says further research is necessary before implementing his methods on embryos other than those slated for PGD. “There could be some subtle risk in removing that one cell. That’s a valid point,” Lanza says.
Beyond these unknown risks, there are other concerns. There is debate over whether the single-celled blastomeres, once removed from embryos, might be able to develop into embryos themselves, scientists say (though there have been no published reports supporting this to date). There is also the risk that if the removed blastomeres do not divide, there is potential for interference in the PGD test, presumably the primary intention of the donation.
“Usually in PGDs, the cells are immediately diverted for diagnosis,” says Dr. George Daley, a stem-cell scientist at Children’s Hospital Boston and the Harvard Stem Cell Institute. “If you wait to see if they’ll divide for the purpose of stem-cell generation, and if some of the cells deteriorate and can’t be used for genetic diagnosis, then you’ve really compromised the PGD process.” Lanza counters this objection by saying that if the blastomere failed to divide, his group would send it off for PGD testing immediately, thereby salvaging the diagnostic procedure.
While Lanza’s project appears to have missed its aim of quelling the ethical concerns of some, Lanza is hopeful that opponents of expanded federal funding of stem-cell research—a minority of Americans according to a July NBC News/Wall Street Journal poll—will come around to his side. “People have been opposed to this for so long, it’s going to be hard for them to make an about-face right away,” he says.
