Means found to convert blood to universal donor O

TORONTO • Canadian researchers believe they have found the means to convert any type of blood into universally usable group O with enzymes found in the human gut — a finding that could expand the pool of potential blood donors and make blood-matching easier and safer.

For transfusions to be safe, blood from a donor — for instance, A, B or AB types — must match that of a patient. O-type blood can be transfused into anyone and is always in high demand.

“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,” said lead researcher Stephen Withers, a professor of chemistry and biochemistry at UBC.

“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,” he said. “That’s why O blood is so important.”

Withers said the UBC team sampled DNA from millions of microorganisms to find one in which the desired enzymes might be found. The researchers then turned their attention to the mucosal lining of the human gut — which contains sugars similar in structure to blood antigens — by extracting bacterial DNA from fecal samples.

“By homing in on the bacteria feeding on those sugars, we isolated the enzymes the bacteria use to pluck off the sugar molecules,” said Withers, adding that researchers then used E. coli bacteria as “little factories” to produce quantities of the enzymes “and found that they were capable of performing a similar action on blood antigens.

“So we just simply add them to the red blood cells, they attach themselves to the surface of the red blood cell and then they cut the sugar off,” he said Wednesday in an interview from Boston, where the research was presented at this week’s American Chemical Society annual meeting.

Scientists have been studying the use of enzymes to modify blood since 1982, said Withers. “However, these new enzymes can do the job 30 times better.”