Therapeutic cloning used in mice

Scientists from the Whitehead Institute for Biomedical Research in Massachusetts, US, report that they have used stem cells created using therapeutic cloning techniques to repair an inherited disease in mice. Although the technique is not yet ready for use in humans, the scientists say that the report is encouraging.

Skin cells were taken from the mice, which had defects of the immune system, and cloned using the nuclear transfer technique. Stem cells extracted from the cloned embryos were genetically altered so that they were free from the immune system defect. Then the stem cells were transplanted back into the mice, where they were seen to partially overcome the immune system defect.

The experiment was carried out by Dr Rudolf Jaenisch and Dr George Daley. Daley said that it was 'a tremendous confluence of very, very challenging technology, wrapping them all up in a model therapy. We are the first to do this all the way'.

Dr Neil Theise, a stem cell scientists at New York University called the results 'dramatic' and said that 'the fact they are doing it in a model of human disease is very canny, and certainly this will have a big impact on the public debate'. The use of cloning techniques and embryonic stem cells in treatments for human conditions is currently being debated in the US Senate, with a vote expected to take place within weeks. Some senators believe that there should be a ban on all forms of cloning. Daley believes that this may be because what is often called therapeutic cloning has a negative association with reproductive cloning and that it should be renamed 'nuclear transplantation therapy' in order to avoid confusion.