Swiss cult backs baby clone doctor

The breakthrough, about to be announced in a leading medical journal, is set to transform heart surgery by giving doctors a new source of replacement veins needed in bypass operations, straight from the laboratory. But it is likely to rekindle fears about the speed at which scientists are mimicking nature. The same American research team is talking about growing human bone to order. Nicolas L'Heureux of the University of California, San Diego, who led the research, said such possibilities had been opened up by the invention of a chemical-filled tank, the bioreactor.

"We mimic the body's environment, and transform the skin cells into blood vessel cells," said Dr L'Heureux. "The biochemical and mechanical environment can influence gene expression, and basically change the behaviour of the cells." To create the replacement blood vessel, the team took skin and vein cells from a human, and mixed them with proteins to create a sheet-like material. This was wrapped around a tube to form a mould, put into the bioreactor filled with amino acids and vitamins, and left to grow. After being mixed with reinforcing cells from the walls of blood vessels, the tube was removed - leaving a length of newly grown vein exactly matching the tissue type of the patient.

"The blood vessel displays the function, look and feel of real tissue," said Dr L'Heureux. "We also avoid the possibility of an immune response that causes complete rejection. As a result, we might be able to make smaller functional vascular grafts, which allow for more perfect matches to the natural blood vessel diameter and thus improve blood flow patterns in the vessel."

Until now, attempts to create all-human parts without synthetic material failed because the tissue was too weak. Researchers had to use artificial materials as reinforcement - increasing rejection risks. Tests on the all-human blood vessel showed it withstood 20 times normal human blood pressure. "This is a fundamental breakthrough that could be used to engineer a variety of tissues," said Prof John Frangos, of the research team, whose results will appear in the Federation of American Societies for Experimental Biology Journal.

Other American scientists say they can regrow replacement parts including women's breasts. The new technique does not involve artifical material, but comprises entirely human tissue.

9 January 1998: Dolly, the cloned sheep, to give birth
8 January 1998: Plea for cash to clone humans
19 December 1997: Sheep clone tops list of year's firsts in science
20 October 1997: Patients' clones 'may grow transplant organs'
12 October 1997: Europe bans human cloning
5 June 1997: Americans to allow cloning of humans
7 March 1997: Human clone 'possible in less than two years'