Nature is reporting that biologists have revealed the details for two different techniques to derive stem cells without embryo destruction that have been purely theoretical until now. While both methods work in mice and could, in principle, be applied to human embryos, scientists, ethicists and politicians are split over two techniques’ merits.
One method, developed by Rudolf Jaenisch and Alexander Meissner of the Massachusetts Institute of Technology, is described as a variant of therapeutic cloning and is dubbed altered nuclear transfer (ANT). In this method 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.
The second method, developed by a team led by Robert Lanza of Advanced Cell Technology in Worcester, Massachusetts, involves plucking single cells called blastomeres from eight-cell embryos. The new ES lines are derived from the blastomere, while the embryos go on to form apparently healthy babies. This raises the possibility of deriving fresh stem-cell lines from human embryos being used for in vitro fertilization before they are transferred to the uterus.
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