There are four blood types - A, B, AB and O. Right now, A and B recipients must receive exactly the same type they have.
Researchers at the University of British Columbia believe they have figured out how to convert all blood types to the almost universal Type O-negative.
Scientists have been studying the use of enzymes to modify blood since 1982, said Withers. Using type-O negative blood in transfusions doesn't lead to unsafe, possibly life-threatening, reactions in the patient.
Withers and his colleagues-UBC microbiologist Steven Hallam and pathologist Jay Kizhakkedathu of the Centre for Blood Research at UBC-are applying for a patent on the new enzymes and are hoping to test them on a larger scale in the future, in preparation for clinical testing.
The researchers started by looking for enzymes that can help them achieve their goals.
Scientists claim they may have identified gut bacteria that could convert blood types A and B into type O.
The team considered sampling DNA from mosquitoes and leeches, the types of organisms that degrade blood, but ultimately found successful candidate enzymes in the human gut microbiome.
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Some of these sugars closely resemble the structure of antigens in A- and B-type blood.
The researchers presented their results today at the 256th National Meeting & Exposition of the American Chemical Society in Boston, Massachusetts.
"We knew that those same sugars that are on our red blood cells are also produced on the lining of the gut wall", Steve Withers told New Scientist, leading them to analyze the enzymes also present there. That's why O blood type donations are so important: as their red blood cells contain no A or B antigens, the antibodies of other groups won't attack them.
Removing antigens from blood effectively transforms it into type O. Withers and his team previously developed enzymes that were capable of doing so, but this latest study identifies a more powerful group of enzymes found in the human gut.
"The next step is very much all about safety", he said. But that particular enzyme, which could convert only type B blood, was too expensive and inefficient for real-world use, said a 2008 review in the British Journal of Haematology.
Because of type-O negative's universality, it is useful in emergency surgery, for instance, when there isn't time to test for a patient's blood type.
"I am optimistic that we have a very interesting candidate to adjust donated blood to a common type", he said. That's why Type O negative blood is always in high demand during emergencies, when there is often little time to test a patient's blood type to make sure it matches a donor.
American Red Cross notably announced a blood shortage in July.