The technology is supposed to be wholly benign. Cloned pigs, for instance, could provide a source of organs for transplant into humans. At the moment, if you need a new liver, a new heart, new lungs or a new kidney, you have to wait until someone with your precise tissue-type dies, and with the organ you want in good condition. That does not happen very often. The result is that only about a third of the people waiting for new organs will get them.
Pigs are physically very close to people.
Their organs will work very well in people. All the technical obstacles to transplanting pig livers or kidneys into humans have been overcome, says Dr Jamas. A pig can now be genetically engineered to ensure that tissue from it will not be rejected by the human immune system. That pig will be cloned - and a potentially limitless source of organs is available for transplant. The nucleus of one of millions of cells in an adult sheep was combined with cytoplasm from one of the same sheep's unfertilised eggs.