VANCOUVER — Researchers at the University of B.C. think they might have found a way to transform a very common type of human blood — type A — into the universally usable type O negative.
This would make blood transfusions much easier, since donor and patient blood types must usually match, unless the donor’s blood is type O negative. Using type O negative blood in transfusions doesn’t lead to dangerous reactions in the patient.
According to Canadian Blood Services, about seven per cent of Canadians have type O negative blood, while 36 per cent have type A positive and six per cent have A negative.
Because of 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.
The UBC researchers said that in their lab tests, a “powerful” group of enzymes found in gut bacteria is able to transform type A positive blood into type O negative by removing antigens from red blood cells.
“Blood type is determined by the presence of antigens on the surface of red blood cells; type A blood has the A antigen, B has the B antigen, AB blood has both antigens and O blood has none,” UBC chemistry professor Stephen Withers said in a statement.
“Antigens can trigger an immune response if they are foreign to the body, so transfusion patients should receive either their own blood type, or type O to avoid a reaction. That’s why O blood is so important.”
Withers and his team previously developed enzymes that were capable of stripping away antigens, but this new kind is more powerful and efficient.
An enzyme-driven process was first discovered in 1982 and research has carried on ever since.
“The [1982] enzyme was incredibly inefficient,” Withers said, adding that the newly discovered enzyme is “thousands” of times better.
“The genomic revolution … has led us to this.”
Previous research uncovered a similar process for type B blood, but Withers said making this work with type A blood was much more important, given how common the blood type is.
“The other big key: our enzyme works on whole blood,” he said. Previous research worked only on blood that had been broken down into component parts.
With this new process, blood taken straight from donors could be quickly converted into type O negative, without much delay.
“If it all works, it will have a big practical advantage.”
After looking at millions of micro-organisms, the researchers determined that the environment in which the desired enzymes might be found is the mucosal lining of the human gut, which contains sugars similar in structure to blood antigens.
“By homing in on the bacteria feeding on those sugars, we isolated the enzymes the bacteria use to pluck off the sugar molecules,” Withers added.
“We then produced quantities of those enzymes through cloning and found that they were capable of performing a similar action on blood antigens.”
Withers and his colleagues — UBC microbiologist Steven Hallam and pathologist Jay Kizhakkedathu from UBC’s Centre for Blood Research — are applying for a patent on the new enzymes and are hoping to test them with the help of Canadian Blood Services on a larger scale in the future, in preparation for clinical testing.
Canadian Blood Services recently made an appeal for blood donors as their supplies, especially in rarer types, are running low. Withers said discovery could ease such pressures in the future.
“Expanding global blood supply is critical in light of growing populations and the frequency of natural disasters,” he said.
The study, funded by the Canadian Institutes of Health Research, was presented Tuesday at the American Chemical Society’s annual meeting in Boston.
