Stanford Experts On New Method Of Deriving Embryonic Stem Cells
Stanford, CA - Stem cell experts at the Stanford University School of Medicine cited several concerns regarding a newly published method of generating human embryonic stem cells without destroying the embryo.
Scientists at Advanced Cell Technologies, a biotech company in Alameda, Calif, published their method in the Aug. 24 issue of the journal Nature.
Current methods of generating embryonic stem cells involve removing the cells from a roughly 5-day-old embryo, destroying the embryo in the process. Because of moral concerns about the destruction of an embryo, President George W. Bush has refused federal funding for the creation of new stem cell lines.
The new method draws on a technique called pre-implantation genetic diagnostics, or PGD, used by in-vitro fertility clinics to check for genetic defects in the embryo. In this technique, one of the embryo's eight cells is removed; the remaining cells are able to grow into a viable embryo for implantation and might therefore overcome the administration's restrictions on funding. According to the Nature paper, the single removed cell can divide to produce a line of normal embryonic stem cells.
Following are comments from four Stanford stem cell experts on the scientific, ethical and political merits of this new technique:
Hank Greely, JD, professor of law and chair of the Stanford Center for Biomedical Ethics steering committee: "From the scientific perspective, never believe anything until it's replicated several times. That's not an accusation of fraud, but science is full of honestly nonreplicable findings. It has to be able to be replicated reliably. Second, speaking still about the science, it will be interesting and important to see if these cells turn out to be the same kind of cells with the same kind of promise as stem cells derived from blastocysts.
"On the ethics side, first it needs to be determined whether these cells can actually be done with embryos subject to pre-implantation genetic diagnosis without jeopardizing the viability of those embryos. This paper does not speak to that at all. They did not use PGD, though the authors say that is the way it should be done. The second ethics point is that some of the people who oppose research on embryos won't view this as protecting an embryo, but as turning it into two embryos and killing the second. It will be interesting to see how much of the embryo-rights movement's opposition might be weakened by this.
"And my one political point: I don't know what the White House will do. It might provide President Bush with a face-saving and politically helpful compromise, even if it doesn't satisfy all of the opponents of embryonic stem cell research."
Irving Weissman, MD, director of the Stanford Institute for Stem Cell Biology and Regenerative Medicine: After talking with Weissman about the study, New York Times science reporter Nicholas Wade wrote: "Scientists welcomed the new development, but also expressed concerns. Dr. Irving Weissman, a stem cell expert at Stanford University, said the new method, if confined to PGD-derived blastomeres, would not provide a highly desired type of cell, those derived from patients with a specific disease."
Weissman's concern is that the newly created stem cell lines would mirror the genetic background of people undergoing IVF. He hopes to see stem cell lines from people with genetic disorders, such as diabetes, cystic fibrosis or Parkinson's disease. Creating stem cells from the cells of people with those diseases would allow researchers to study how the disease develops and how the cells respond to drug treatments.
David Magnus, PhD, director of the Stanford Center for Biomedical Ethics: "While the work by Advanced Cell Technologies is very interesting and might be a potentially interesting additional way of procuring and developing embryonic stem cells, it is deeply misguided to think of this as a solution to the ethical controversy over human embryonic stem cell research.
"First, it is unlikely that all (and perhaps not even most) opponents of embryonic stem cell research will agree that this eliminates their ethical objections. To use the techniques discussed, there must be a commitment to accepting in-vitro fertilization and PGD -- but since this results in the creation and destruction of embryos, most opponents of embryonic stem cell research will object to this as well. In addition, while it is unlikely that the separated blastomeres have the capacity to develop into humans, it has not been shown to be impossible. For many of the opponents of embryonic stem cell research, that distinction matters. Otherwise, the opponents would accept somatic cell nuclear transfer (another experimental method of creating stem cells) using adult somatic cells, since it is unlikely that any of these can ever develop into a human.
"Second, and most importantly, the idea of trying to find a consensus is deeply flawed. The principle that there should not be research that some individuals oppose would lead us to abandon all evolutionary and population genetics research (since creationists oppose it), research on animals (many oppose all research on animals) and possibly all research (since there are people who oppose most biotechnology). Attempting to find a 'common ground' is really a strategy designed to provide political cover to those who oppose embryonic stem cell research (an unpopular position). It is as likely to succeed as trying to find an abortion method that right to life groups will find morally acceptable."
Christopher Thomas Scott, executive director of the Stanford Program on Stem Cells in Society, which is part of the biomedical ethics center: "In terms of the science, it's an important result because it breaks the species barrier. In cell biology, going from animal models to primates models is difficult, so when you successfully replicate a result from animals in humans, that's a big result. Advanced Cell Technologies has transferred the result from an animal model to a primate model -- that in itself is enough to take notice.
"From the moral perspective, it solves a few problems, but not the big one -- notably the objection of those people who believe that the embryo has rights and is a human being and that experimenting on an embryo that cannot give its consent is using the embryo as a means to an end."
SOURCE: Stanford University Medical Center