The artificial blood is a haemoglobin solution made from the oxygen carrying part of the red cells in human blood and is being tested in trauma cases. Because the red cell surfaces are missing, patients do not have to be typed and blood cross- matched before transfusion.
The product has been developed by the US-based Baxter Healthcare, which has overcome the difficulty that pure haemoglobin naturally tends to break into two molecules and be rapidly excreted from the body. To prevent that, Baxter has found a way of locking the two sub- units together with an aspirin derivative that makes the haemoglobin an efficient oxygen deliverer and allows it to be heat treated. That inactivates any viruses and removes cell antigens that could set up reactions in patients.
The company is taking the haemoglobin from blood donations that have passed their 35-day shelf life - a fate that on average befalls about 5 per cent of donations in England. Dr Martha Farmer, product development manager, said the purified solution was dark red, looking much like blood, although unlike blood, if held up to the light, it was see-through.
Aside from being used in accident, injury and shock cases where oxygen delivery and fluid bulk is needed, one of the artificial blood's most exciting possibilities is that it may offer a treatment for strokes.
In animal studies, the haemoglobin solution, because it is physically smaller than red blood cells, has been found able to go round blood clots and reach parts of the brain being oxygen-starved by the clot. Infusion of the solution soon after a stroke appears to reduce the damage done to brain tissue and thus the effects of the stroke, which in humans can leave victims paralysed or their memories and speech affected.
If trials go well, Baxter hopes to launch the blood substitute in Europe in two years, although Dr Farmer warned it would not reduce the need for donors because it is derived from human haemoglobin. But it will cut the waste of out-dated blood, allow blood to be used more flexibly and the resulting artificial blood to be stored for long periods.
To have a significant impact on the world shortage of blood, genetically engineered haemoglobin - a fully manufactured product rather than one derived from blood - would have to reach the market. Several companies are working on that, with the US company Somatogen developing a product in co-operation with scientists from the Medical Research Council.
The Scottish Blood Transfusion Service yesterday insisted that NHS patients 'will always come first' after it was criticised for signing a contract to supply the new pounds 180m Clydebank private hospital in Glasgow, which is expected to treat an international clientele. David McIntosh, the service's general manager, said all its contracts with private hospitals specified that if there was any blood shortage, supplies would go first to the NHS and that blood already supplied could be recalled from private hospital fridges into the NHS if needed.
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