Thursday, June 24, 1999 Published at 10:34 GMT 11:34 UK
Cloning may lead to 'medical revolution'
This cloned human embryo was used to harvest stem cells by Advanced Cell Technology
British scientists want the UK Government to allow limited cloning of human embryos because they believe a "medical revolution" could result from the research.
The technology centres on human embryonic stem cells. These are the "master" cells which have the potential to become any of the body's many different types of tissue.
For example, a healthy skin cell could be taken from a leukaemia sufferer and cloned by creating a human embryo. The stem cells produced by the embryo could then be grown and multiplied into bone marrow cells for transplantation.
But this treatment cannot happen without cloning, some scientists argue. Only embryos producing the early-stage cells which have the potential to develop into any tissue cell.
Scientists in America have already succeeded in isolating and growing cultures of human embryonic stem cells. Details of human embryos cloned in November 1998 by Advanced Cell Technology were released recently.
Cells not babies
The type of human cloning suggested by the two scientific panels to aid medical research is called "therapeutic" cloning. It is likely that the age limit for these human embryo clones will be no more that 14 days. At that point they would be destroyed.
Therapeutic cloning is expressly not aimed at creating living copies of human beings. This "reproductive" cloning should be specifically banned by law said the two scientific panels.
The laboratory at Roslin, Edinburgh which cloned the sheep Dolly have so far been unable to produce a pig clone. There is also doubt over the longer-term health of adult clones, which could suffer from genetic defects and premature ageing.
However, cloning opponents believe that any change in the law which allows therapeutic cloning will allow scientists the refine their methods and make the likelihood of the birth of a human clone much greater.