New Methods to Derive Embryonic Stem Cells
New Methods to Derive Embryonic Stem Cells
If you are interested in stem cell research, you have probably already heard by now about the studies published in this week’s issue of Nature involving new ways to derive embryonic stem cells in mice. These have been widely covered by the media, so in this post I’ll give you several brief summaries as they have appeared in different sources. The story will probably continue to circulate for some time.
The nature.com website reports on the two studies. The article lays the background about the ethical concerns regarding creating and destroying an embryo for the purpose of obtaining stem cells, then discusses the two studies on mice. In the first study, researchers at MIT performed an SCNT variant called “altered nuclear transfer” (ANT) in which a gene in the donated egg is switched off. The result is the growth of a blastocyst from which embryonic stem cells can be derived but which is unable to implant in a uterus and develop into a fetus. In the second study, researchers at Advanced Cell Technology in Massachusetts took single cells known as blastomeres from eight-cell embryos. The blastomeres were used to derive ES lines, while the embryos went on to develop into healthy mice. This technique is similar to one already used in IVF procedures, known as preimplantation genetic diagnosis (PGD).
The article then goes on to give some opinions of other researchers on the studies. The PGD method has the disadvantage that the cells derived are only a genetic match for the couple who underwent IVF treatment, not for the prospective patient. Some people are also concerned that the blastomere also has the potential to develop into a viable embryo on its own. Another concern that has been voiced is potential damage to the baby which develops from the embryo from which the blastomere was removed.
The ANT method, on the other hand, is seen by some as destroying the embryo through engineering a mutation. So to the question of “What is a human?” has now been added the question of “What is an embryo?”
The Christian Science Monitor reports on the study as well. The article begins by addressing the ethical concerns and the quest for a way to resolve them, and includes the following:
This broad lab-based approach "is encouraging," says the Rev. Tadeusz Pacholczyk of the National Catholic Bioethics Center in Philadelphia, who holds a doctorate in neuroscience from Yale University. "You're using the power of science to develop a solution that gets around a very grave moral objection."
The article repeats the methods and results of the studies and summarizes opinions of several other un-named scientists, who believe that the ANT method would take away money from SCNT research. The scientists “added that the approach doesn't solve any ethical dilemma because in their view it incorrectly presumes that the ethical standing of an individual hinges on the action of a single gene.”
The English language version of the Chinese Xinhuanet reports a few more details on the ANT procedure; the researchers used RNA interference to target the Cdx2 gene. They then had to repair this and re-enable the gene in the derived stem cells.
Forbes picked up the HealthDay News version of the story, which included a number of quotations from various scientists, including Dr. Robert Lanza, one of the researchers in the PGD method. The article also had the following:
A statement from Dr. Robert Schenken, president of the American Society for Reproductive Medicine, added a cautionary note.
"The research by Professor Jaenisch and Professor Lanza and their colleagues announced today represent important steps forward in the rapidly evolving field of stem cell science," the statement read. "It is essential to note that both of these studies, while potentially very important, are also very preliminary. There is much work to do before any of this might be applied to human beings. Thus far, our work in many other areas has taught us that in reproductive medicine, what works in animals may not translate well to humans."
An AP story picked up by the Columbus Dispatch quoted Richard Doerflinger, deputy director of pro-life activities for the Catholic bishops conference, as saying that the PGD method was a way “to select out genetically imperfect embryos” and also posed a risk of harm. Doerflinger also said that the ANT method was creating an embryo and then destroying it. However, the AP story quoted the Rev. Pacholczyk as saying that it was a step in the right direction.
The Australian reported on the PGD method, including a quote from parliamentary health secretary Christopher Pyne: "I object to the idea that embryos are available for research where I think they should be treated with some respect, rather than treated as a resource upon which human beings can experiment and interfere with.”
The study is also reported, with a number of different people weighing in, in the San Francisco Chronicle, the Boston Globe, Science Daily (UPI), the Washington Post, Reuters, the BBC, the Sydney Morning Herald, and others. The studies appear to have raised as many issues as they might resolve on the ethical front. It is still of course unknown how well either procedure would work on humans as opposed to mice.