CLONING has been used for the first time to grow tailor-made embryonic stem cells in unfertilised human eggs.

The US breakthrough could result in damaged tissue and organs being repaired or replaced without the risk of rejection by the immune system.

The research, in the journal Nature, shows it is possible to use cloning technology known as somatic cell nuclear transfer (SCNT) – the technique behind Dolly the Sheep – to create embryonic stem cells that match a patient’s own DNA.

These patient-specific cells could potentially be transplanted to replace damaged cells in people with diabetes and other diseases without the risk of rejection normally associated with transplant because the immune system would recognise the new cells’ DNA – instead of fighting back against the “foreign” DNA of a donor.

Normally, SCNT involves removing genetic material from the nucleus of the host egg cell and replacing it with the nucleus from adult cells. However, scientists have failed to get these cells to grow and divide beyond a very early stage.

Instead, scientists in the New York study kept the genetic material from the host egg and added the nucleus from the adult cells. Although they failed to obtain useful cell lines, the technique showed stronger results compared to the standard method.

Professor Robin Lovell-Badge, a division head at Britain’s National Institute for Medical Research, said: “Stem cells are the body’s master cells, which can be grown into any type of specialist cell in the body.”