Professor Moon and his colleagues at Seoul National University, South Korea, took 242 eggs from 16 healthy donors. Using the cloning technique somatic cell nuclear transfer (SNCT), the researchers removed the nucleus of each unfertilised egg and replacing it with the nucleus taken from a cell from the cumulus - the clump of cells that surrounds the egg - of the donor. The eggs were then stimulated to begin dividing and after a few days 30 blastocysts were produced. From these the researchers were able to extract one colony of stem cells.
Although the procedure is highly experimental and still needs refinement, its publication was greeted with great enthusiasm because of its potential to produce stem cells which are genetically identical to the donor. In principle stem cells can be directed to develop into any tissue.
"This means that patients who received them as part of a treatment would not reject the cells as foreign", said Professor Moon. "We call this therapeutic cloning to differentiate it from reproductive cloning, where the aim would be to implant the cloned embryo into a woman in order to produce a baby. In therapeutic cloning, the embryo is destroyed after the stem cells have been harvested."
Scientists believe that therapeutic cloning holds great promise for the treatment of a large number of currently untreatable conditions, including many inherited diseases.
"Our first attempt was clearly not very efficient", said Professor Moon. "We only managed to harvest one stem cell line. We do not know whether this was due to something going wrong in the development of the cloned embryo, or whether we need to make small variations in our experimental procedures. But this will become clearer as we proceed.
"In the meantime, we believe that we have opened the door to an extraordinary revolution in medicine, where one day transplanting organs from other donors will become a thing of the past, and where millions of people with have access to life-saving therapies developed from their own DNA," he said.