http://www.nature.com/news/2005/051010/full/4371072b.htmlResearchers claim to have found an ethical way to harvest embryonic stem cells
Published online: 16 October 2005; | doi:10.1038/4371072b
'Ethical' routes to stem cells highlight political divide
Split opens over methods to create nonviable embryos.
<snip>Until now, such methods have been purely theoretical, but in work published online by Nature this week, two teams report their successful use in mice. Rudolf Jaenisch and Alexander Meissner of the Massachusetts Institute of Technology describe a variant of therapeutic cloning called altered nuclear transfer (ANT), in which a gene in the patient's donated cell is switched off before the nucleus is transferred into a fertilized egg. The resulting egg grows into a normal ball of cells called a blastocyst from which ES cells can be derived, but the deactivated gene means that the ball lacks the ability to implant in a uterus and so develop into a baby (A. Meissner and R. Jaenisch Nature doi:10.1038/nature04257; 2005).
In the other paper, a team led by Robert Lanza of Advanced Cell Technology in Worcester, Massachusetts, plucked single cells called blastomeres from eight-cell embryos. They derived new ES cell lines from the blastomere, while the embryos went on to form apparently healthy mice (Y. Chung et al. Nature doi:10.1038/nature04277; 2005).
This method is similar to a technique used in in vitro fertilization (IVF) called preimplantation genetic diagnosis (PGD), in which a blastomere is removed from the eight-cell embryo for genetic tests before it is implanted. The work by Lanza's team raises the possibility that fresh stem-cell lines could be derived from human embryos being used in IVF before they are transferred to the uterus.
<snip>And either way, the ethical debate over what constitutes life ? or the potential for life ? looks set to dog the field. "The challenge is to define what an embryo is," says Hurlbut. "We need to sort that out or we'll be having this argument all the way along."