Artificial blood created from stem cells could be tested on Britons within two years.
The scientists behind the research, which could provide industrial scale quantities of blood, believe it will transform transfusions by preventing hospital shortages, and save thousands of lives on battlefields and at the scene of car crashes.
Heart transplant, bypass and cancer patients would also benefit from having a guaranteed supply of blood on hand for their surgery.
The â€˜holy grailâ€™ of blood research, the man-made blood would be free of infections that have blighted natural supplies and could be given to almost everyone regardless of blood group.
The hope comes from Edinburgh and Bristol university researchers who have, for the first time, made thousands of millions of red blood cells from stem cells â€“ â€˜master cellsâ€™ seen as a repair kit for the body â€“ taken from bone marrow. But with the average blood transfusion containing 2.5million million red blood cells, this is not enough.
Cells taken from human embryos in the first days of life are easier to multiply in large numbers, but the researchers have so far not managed to make such realistic blood.
If they crack the recipe, just one embryo could theoretically provide all the cells ever needed for Britainâ€™s blood supply.
Edinburgh Universityâ€™s Professor Marc Turner hopes to make a supply of cells with the O-negative blood type. This â€˜universal donorâ€™ blood could be given to up to 98 per cent of the population.
A supply of safe blood would also be a boon in developing countries, where thousands of lives are lost to conditions such as haemorrhages after childbirth. Mr Turner predicts that in two to three years, he will be ready to inject a teaspoon of man-made blood into healthy volunteers, in the first British trial of blood from stem cells.
Large-scale trials would follow, but the blood could be in routine use in a decade. Within 20 years, it may be possible to produce two million pints of artificial blood a year â€“ enough to satisfy the nationâ€™s medical needs. Any embryonic stem cells used would be taken from four or five-day-old embryos left over from IVF treatment and donated to the research project.
Research: The scientists are turning stem cells - master cells, widely seen as a repair kit for the body, into red blood cells (file picture)
Critics say it is wrong to plunder an unborn child for â€˜spare partsâ€™ to advance medical science.
But Mr Turner, who is funded by the Wellcome Trust, said: â€˜There is a lot of regulatory framework to ensure that the cells are being treated with the appropriate respect and being used for genuine scientific and medical reasons and not in a trivial fashion.â€™
He added that a recent European decision to ban the patenting of treatments based on embryonic stem cells means his focus is likely to switch to other sources of cells.
Chris Mason, professor of regenerative medicine at University College London, described the research as â€˜fascinatingâ€™ and a safe, ready supply would make a â€˜massive differenceâ€™ to patients.
He added that production could be geared to demand, with bigger supplies on hand in the summer when there are more car crashes and gun fights. And while there are fears other â€˜body partsâ€™ made from stem cells can trigger cancer, blood cells should be free of this risk.
Blood donation services from around the UK and Ireland are providing the scientists with practical help and expertise. Lorna Williamson, of NHS Blood and Transplant, said the research was encouraging but â€˜we will continue to rely, for some years to come, on our loyal, regular blood donors to help us meet the needs of patients for vital bloodâ€™.
Mr Turner, who is also the associate medical director of the Scottish National Blood Transfusion Service, is far from the only scientist in the race to crack the billion-pound market in artificial blood.
The French have started early-stage human trials with stem cell blood and other researchers around the world are making haemoglobin, the red blood cell protein used to ferry oxygen around the body.
Ideas being pursued elsewhere include using haemoglobin taken from cows as a blood substitute.
Some 1.6million Britons give blood each year. In the UK, stocks can fall during holiday periods, with supplies of the highly versatile O-negative type particularly vulnerable.