Some human embryonic stem cell researchers recently have questioned whether methods used in a study published in the Aug. 24 edition of the journal Nature were sufficient to conclude that human embryonic stem cells could be created without destroying the embryo, the Wall Street Journal reports (Hamilton/Regalado, Wall Street Journal, 9/5).
In the study, Robert Lanza, medical director of Worcester, Mass.,-based Advanced Cell Technology, and colleagues described the technique as removing a single cell -- known as a blastomere -- from a three-day-old embryo with eight to 10 cells and using a biochemical process to create embryonic stem cells from the blastomere. Researchers removed 91 blastomeres from 16 thawed embryos donated by fertility clinic patients and found that more than half of the blastomeres began to multiply and that in two cases the blastomeres became embryonic stem cells. The method of removing a cell from the embryo is based on preimplantation genetic diagnosis, or PGD, which usually is used to test the cell for genetic deficiencies. At the time the Nature article was published, Lanza said the research destroyed some of the embryos used but single-cell extractions that leave the embryo unharmed should be feasible in the future (Kaiser Daily Women's Health Policy Report, 9/1). Although the blastomeres removed by the researchers from the embryos were separate, multiple blastomeres shared a common fluid in the same laboratory dish, which could have allowed them to exchange proteins and other factors linked to growth, according to the Journal. "One of the flaws in this paper is that it draws conclusions that they don't really have the data to prove," Barry Behr, director of Stanford University's IVF Laboratories, said, adding, "The sort of leaps of faith here are a little too big to leap." Lanza said ACT researchers have successfully grown a blastomere with its parent embryo for about one day following separation, adding that it should be possible to culture blastomeres from separate embryos in the same lab dish (Wall Street Journal, 9/5).
Nature Changes