Last year, Bob Lanza and his team from Advanced Cell Technology of Worcester, Massachusetts, demonstrated that stem cells could be harvested from mouse embryos without killing them (see Are all human embryos equal?). Now they have done the same in human embryos left over from IVF treatment.The obligatory skeptic, though, responds later in the article:
The researchers employed a technique used in pre-implantation genetic diagnosis (PGD) in which a single cell or “blastomere” is removed from the ball of eight to 10 cells that comprise the early embryo. The researchers were able to grow a stem cell line from just one or two cells from an early embryo - leaving that embryo viable. The cells are “pluripotent”, meaning they can grow into the three major tissue types (Nature, DOI: 10.1038/nature05142).
IVF embryos that have been biopsied for PGD have grown into normal babies, says Alison Murdoch of the International Centre for Life in Newcastle upon Tyne, UK. “However, it is not true to say the biopsy is not detrimental to the embryo,” she says. “Some embryos do not survive.”Once the technique is refined, that may no longer be the case. At any rate, it's a potentially revolutionary development in a field that has seen far more hype than hope.
Update: As far as the end of the debate goes, Ed Brayton is slightly less optimistic.