Britain's embryo research watchdog may press the government to reform laws that bar British scientists from work which could allow human organs to be grown in the laboratory.
The Human Fertilisation and Embryology Authority may ask the government to broaden existing legislation following a breakthrough by United States scientists.
The advance has been made possible by isolating the stem cells from human embryos. It is from these cells that all types of human tissue are derived. Once isolated, the development of the stem cells is arrested, providing a window of opportunity for scientists to manipulate them so that they become specialised cells that can be used for transplantation.
The creation of nerve cells to treat Parkinson's disease, and pancreatic cells for diabetes, are among the long-term possibilities of the breakthrough. Using cloned human cells to generate stem cells when the technique is perfected would overcome the critical problem of rejection of transplants.
Under UK law, the US research, carried out by scientists at the University of Wisconsin and Johns Hopkins University, would not be allowed, being outside the five categories for which embryo research licences may be granted by the HFEA. The authority says the possible need to recommend adding new categories to its remit is being considered as part of a consultation exercise on implications of cloning technology for humans. The consultation is being carried out jointly with the Human Genetics Advisory Commission.
Austin Smith, an expert based at the centre for genome research at Edinburgh University, called for two alterations to the 1990 Human Fertilisation and Embryology Act.
First, he wants criteria for embryo research to be broadened to allow the creation of cells for use in transplantation. And while he does not support the use of cloning technology for the production of foetuses for implantation, Mr Smith urges the authority and government to change the law to allow cloning of human cells for therapeutic or biomedical research.
He said: "Cloning human cells has nothing to do with creating life. The kind of work that is going on in the US will also be carried out in countries such as China and Japan. We will not be at the stage when we can exploit work in the field for some time yet but we can start doing the research. If it is going to take five years to change the law we will lose out. The time is right now to review the laws."
Harry Griffin, assistant director at the Roslin Institute, said: "We are opposed to practical applications of cloning that lead to implantation for reproduction but the potential for therapeutic applications is great. Our broad plea to the authority is that it should make the distinction between the two and consider changing the 1990 act if necessary."
An HFEA spokesman said it is "actively consideringI whether to advocate the use of therapeutic cloning and also whether to recommend to government that the legal justification of human embryo research be broadened".