Insulin-making cells created by Dolly-cloning method

The dream of generating a bank of stem cells to treat injury and illness is a step closer. Embryonic stem cells have been custom-made from adult cells without manipulating the cell's genes, a process that could trigger cancer.

Using a similar cloning technique to the one that created Dolly the sheep, two teams have independently shown that it is possible to turn an adult cell into an embryonic stem cell, which can then become any cell in the body.

To achieve the feat, the teams – one led by Young Gie Chung at the CHA University in Seoul, South Korea, and the other by Dieter Egli at the NYSCF – first removed the nucleus of a donated human egg and replaced it with the nucleus from an adult skin cell. Caffeine was added to stop the cell dividing too quickly, buying time for the genes in the egg's new nucleus to revert to an embryonic state. Electrical pulses and chemicals fooled the cell into thinking it was fertilised, prompting it to divide and multiply.

The result was a bundle of 60 to 200 cells – the first time an adult cell has been used to make a cloned human embryo. In the centre of the bundle were embryonic stem cells that can differentiate into any cell in the body given the right environment.

One team used the technique, called somatic cell nuclear transfer (SCNT), to transform skin cells from a woman with diabetes into insulin-producing beta cells that could replace those destroyed by the disease. The approach has the potential to replace many other types of tissue including heart cells, neurons and cartilage. This could spur on treatments for Parkinson's disease, multiple sclerosis and liver disease, and repair damaged bones.