The method used is called somatic cell nuclear transplant. It involves taking an unfertilized egg and removing its nucleus, thereby deleting the DNA of the egg donor. At the same time, a nucleus from the cell of a donor is carefully removed and injected into the egg. After some time, during which the environment of the egg resets the developmental status of the donor’s DNA, cell division is activated. If the process is successful, the end result is a small cluster of cells that starts along the path of forming an embryo.
This technique was recently used to create embryonic stem cells from an infant donor. But the new team managed to perform the technique successfully with two male donors, one 35 years old and the second 75. The primary change needed was simply to extend the period in which the donor DNA is reset by the proteins present in the egg.
via Ars Technica
