A BRITISH laboratory and a US firm are collaborating to produce artificial blood after scientists overcame two obstacles that had hampered this effort. Attempts to use haemoglobin isolated from the red blood cells as "artificial" blood failed because it caused kidney damage and was unable to give up oxygen -- its main function. Using genetic engineering, scientists modified the haemoglobin gene and tricked bacteria into producing a sub-unit of the haemoglobin molecule.

By simply fermenting bacteria carrying the haemoglobin gene, an unlimited amount of this artificial oxygen carrier can be produced. With this breakthrough, Somatogen Inc and the Medical Research Council Laboratory of Molecular Biology in Cambridge should be able to provide a blood substitute that is cheap and free of viruses like the AIDS-causing HIV and various hepatitis strains.